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STUDY DESIGN A laboratory study performed in a self-controlled fashion. OBJECTIVE The aim of this study was to examine whether "surgical smoke" generated by using the electrocautery on porcine spinal tissues could contain viable bacteria. SUMMARY OF BACKGROUND DATA The year 2020 has seen a surge in legislation regarding surgical smoke evacuation in the operating room across the United States. Surgical smoke contains numerous toxic and carcinogenic substances, which spine surgeons and operating room staff are regularly exposed to. Although the smoke's chemical toxicity has been extensively studied, little is known about its biohazard level. METHODS The electrocautery was used to "operate on" 20 segments of porcine spinal tissues on a clean bench. In each operation, the generated smoke was captured with a swab, which was positioned above the surgical site and within the smoke, to obtain bacteria cultures. Two other swabs-a tissue swab (swabbing the porcine tissue itself) and a blank swab (swabbing an empty sterile bowl)-were collected as controls. The culture results were compared among the three groups. An additional experiment was conducted to see whether using a mask can reduce the "infection rate" of the swab. RESULTS Although all blank swabs tested negative, 95% (19/20) of the smoke swabs tested positive, with a total of nine bacteria species identified. The most prevalent species observed in the smoke swabs included Serratia liquefaciens, Lactococcus garvieae, and Hafnia alvei, and so on. Among the positive smoke swabs, 84% (16/19) had one or more bacteria species that were consistent with the cultures of their corresponding tissue swabs. Using a surgical or N95 mask reduced the "infection rate" of the swab. CONCLUSION "Surgical smoke" generated by electrocauterization of porcine spinal tissues contains viable bacteria. Further research in actual spine surgery is needed next.Level of Evidence: N/A.

Background Total knee arthroplasty (TKA) and lumbar spine surgery have been reported to affect the outcomes of each other. There is insufficient evidence to guide the choice of treatment order for patients with both disorders that are equally symptomatic. Methods Five clinical scenarios of concurrent, advanced, degenerative knee and lumbar spinal disorders were designed to survey surgeons’ choices of treatment order and rationale. The spinal disorder was consistently degenerative lumbar spinal stenosis, but the knee conditions varied to include (1) osteoarthritis (OA) with varus deformity, (2) OA with valgus deformity, (3) rheumatoid arthritis with a severe flexion contracture, (4) OA without deformity, and (5) bilateral OA with windswept deformities. The survey was distributed to selected clinical members of the Knee Society and Scoliosis Research Society in North America. The surgeons’ choices were compared among the 5 scenarios, and their comments were analyzed using text-mining. Results Responses were received from 42 of 74 (57%) knee arthroplasty surgeons and 55 of 100 (55%) spine surgeons. The percentages of knee arthroplasty surgeons recommending “TKA first” differed significantly among scenarios: 29%, 79%, 55%, 7%, and 81% for scenarios 1 through 5, respectively (P Conclusion For patients with concurrent degenerative knee and lumbar spinal disorders, the severity and type of knee deformity influenced the preference of treatment order in both specialties. Severe valgus deformity and windswept deformities of the knee would drive the decision toward “TKA first.”

BACKGROUND CONTEXT Cervical epidural steroid injections (CESIs) are sometimes used in the management of cervical radicular pain in order to delay or avoid surgery. However, the rate and determinants of surgery following CESIs remain uncertain. PURPOSE This study sought to determine: 1) the proportion of patients having surgery following CESI, and 2) the timing of and factors associated with subsequent surgery. STUDY DESIGN Retrospective analysis of a large, national administrative claims database. PATIENT SAMPLE The study included 192,777 CESI patients (age 50.9±11.3 years, 55.2% female) who underwent CESI for imaging-based diagnoses of cervical disc herniation or stenosis, a clinical diagnosis of radiculopathy, or a combination thereof. OUTCOME MEASURES The primary outcome was the time from index CESI to surgery. METHODS Inclusion criteria were CESI for cervical disc herniation, stenosis, or radiculopathy, age ≥18, and active enrollment for 1 year prior to CESI to screen for exclusions. Patients were followed until they underwent cervical surgery, or their enrollment lapsed. Rates of surgery were assessed with Kaplan-Meier survival curves and 99% confidence intervals. Factors associated with subsequent surgery were assessed with multivariable Cox proportional hazard models. RESULTS Within 6 months of CESI, 11.2% of patients underwent surgery, increasing to 14.5% by 1 year and 22.3% by 5 years. Male patients and those aged 35-54 had an increased likelihood of subsequent surgery. Patients with radiculopathy were less likely to undergo surgery following CESI than those with stenosis or herniation, while patients with multiple diagnoses were more likely. Patients with comorbidities including CHF, other cardiac comorbidities or chronic pain were less likely to undergo surgery, as were patients in the northeast US region. Some 33.5% of patients underwent >1 CESI, with 84.6% of these occurring within 1 year. Additional injections were associated with reduced rates of subsequent surgery. CONCLUSIONS Following CESI, over one in five patients underwent surgery within 5 years. Multiple patient-specific risk factors for subsequent surgery were identified, and patients undergoing repeated injections were at lower risk. Determining which patients may progress to surgery can be used to improve resource utilization and to inform shared decision-making.

The study objectives were to use a large national claims data resource to examine rates of preoperative epidural steroid injections (ESI) in lumbar spine surgery and determine whether preoperative ESI or the timing of preoperative ESI is associated with rates of postoperative complications and reoperations.A retrospective longitudinal analysis of patients undergoing lumbar spine surgery for disc herniation and/or spinal stenosis was undertaken using the MarketScan® databases from 2007-2015. Propensity-score matched cohorts were constructed to compare rates of complications and reoperations in patients with and without preoperative ESI.Within the year prior to surgery, 120,898 (46.4%) patients had a lumber ESI. The median time between ESI and surgery was 10 weeks. 23.1% of patients having preoperative ESI had more than one level injected, and 66.5% had more than one preoperative ESI treatment. Patients with chronic pain were considerably more likely to have an ESI prior to their surgery [OR 1.62 (1.54, 1.69), p 0.001]. Patients having preoperative ESI within in close proximity to surgery did not have increased rates of infection, dural tear, neurological complications, or surgical complications; however, they did experience higher rates of reoperations and readmissions than those with no preoperative ESI (p 0.001).Half of patients undergoing lumbar spine surgery for stenosis and/or herniation had a preoperative ESI. These were not associated with an increased risk for postoperative complications, even when the ESI was given in close proximity to surgery. Patients with preoperative ESI were more likely to have readmissions and reoperations following surgery.

Shared decision-making between patients and physicians involves educating the patient, providing options, eliciting patient preferences, and reaching agreement on a decision. There are different ways to measure shared decision-making, including patient involvement, but there is no consensus on the best approach. In other fields, there have been varying relationships between patient-perceived involvement and observed patient involvement in shared decision-making. The relationship between observed and patient-perceived patient involvement in decision-making has not been studied in orthopaedic surgery.(1) Does patient-perceived involvement correlate with observed measurements of patient involvement in decision-making in orthopaedic surgery? (2) Are patient demographics associated with perceived and observed measurements of patient involvement in decision-making?We performed a prospective, observational study to compare observed and perceived patient involvement in new patient consultations for eight orthopaedic surgeons in subspecialties including hand/upper extremity, total joint arthroplasty, spine, sports, trauma, foot and ankle, and tumor. We enrolled 117 English-literate patients 18 years or older over an enrollment period of 2 months. A member of the research team assessed observed patient involvement during a consultation with the Observing Patient Involvement in Decision-Making (OPTION) instrument (scaled 1-100 with higher scores representing greater involvement). After the consultation, we asked patients to complete a questionnaire with demographic information including age, sex, race, education, income, marital status, employment status, and injury type. Patients also completed the Perceived Involvement in Care Scale (PICS), which measures patient-perceived involvement (scaled 1-13 with higher scores representing greater involvement). Both instruments are validated in multiple studies in various specialties and the physicians were blinded to the instruments used. We assessed the correlation between observed and patient-perceived involvement as well as tested the association between patient demographics and patient involvement scores.There was weak correlation between observed involvement (OPTION) and patient-perceived involvement (PICS) (r = 0.37, p0.01) in decision-making (mean OPTION, 28.7, SD 7.7; mean PICS, 8.43, SD 2.3). We found a low degree of observed patient involvement despite a moderate to high degree of perceived involvement. No patient demographic factor had a significant association with patient involvement.Further work is needed to identify the best method for evaluating patient involvement in decision-making in the setting of discordance between observed and patient-perceived measurements. Knowing whether it is necessary for (1) actual observable patient involvement to occur; or (2) a patient to simply believe they are involved in their care can inform physicians on the best way to improve shared decision-making in their practice.Level II, therapeutic study.

This is a retrospective study.To compare (1) recurrence of radiculopathy and (2) back pain after decompression with and without fusion for patients with a symptomatic synovial cyst.Previous work described favorable outcomes following cyst excision with and without fusion. Because of the association of facet cysts with spinal instability it is hypothesized that a decompression with fusion will lead to better outcomes. However, previous studies present contradicting results.We included 314 consecutive patients that underwent operative treatment for a facet cyst between 2003 and 2013 at 2 tertiary spine referral centers: 224 (71%) underwent decompression without fusion (35% spondylolisthesis), 90 (29%) underwent decompression with fusion (63% spondylolisthesis). Baseline data were compared between the groups. Bivariate log-rank analysis was used to compare outcomes between groups, followed by multivariable Cox regression analysis accounting for differences in baseline characteristics.Patients undergoing decompression with fusion presented with a higher incidence of back pain (P=0.004) and spondylolisthesis (P0.001), had more often bilateral decompressions (P0.001), more facetectomies (P0.001), and more levels of decompression (P=0.004) than those who underwent decompression alone. We found a difference in recurrence of radiculopathy (no fusion: 25% vs. fusion: 9.4%, P=0.029) in bivariate analysis. However, this difference did not hold when accounting for confounders (hazard ratio, 0.50, 95% confidence interval, 0.19-1.31, P=0.16). There was no difference in recurrence of back pain in bivariate (no fusion: 29% vs. fusion: 22%, P=0.51) and multivariable analysis (hazard ratio 0.51, 95% confidence interval, 0.23-1.14, P=0.10).We found, with the numbers evaluated, no difference in recurrence of radiculopathy or back pain between patients undergoing decompression with or without fusion after accounting for confounders. The decision for fusion should be considered in light of the extent of decompression and the existence of other pathology.Level III-therapeutic study.

STUDY DESIGN This is a surgical strategy survey. OBJECTIVE The purpose of this study was to evaluate the variability in in surgical strategy planning of adult spinal deformity (ASD) based on patients' clinical and radiographic data. BACKGROUND Literature guiding the management of ASD consists primarily of studies with low levels of evidence. Recent studies have demonstrated good agreement among surgeons about the factors influencing surgical decision but poor agreement about the need for surgery. Therefore there is a relative lack of consensus and guidelines in the clinical practice and treatment of ASD. METHODS A total of 28 adult deformity surgeons were asked to fulfill an online survey of 10 spinal deformity cases. Case presentation included a clinical vignette with photographs, Oswestry Disability Index and Visual Analog Scale scores and imaging with radiographic measurements. For each case, the surgeons were asked whether surgical management would be beneficial and if so, their surgical plan (approach, staging, need for fusion, osteotomy or decompression and the techniques used). Intraobserver and interobserver reliability were studied using average Cohen and Feiss Kappa statistics, respectively. Descriptive statistics were calculated to evaluate the frequency of each of the alternatives in surgical planning. RESULTS Average intrarater and interrater agreement for surgical strategy were evaluated to be substantial (κ=0.62) and fair (κ=0.24), respectively. Detailed interrater statistics demonstrates that there was only slight agreement on the need for surgery (κ=0.15), the approach (κ=0.15), and the need for fusion (κ=0.16) while moderate agreement was reached for the need for decompression (κ=0.42) and osteotomy (κ=0.29). CONCLUSIONS Among surgeons, agreement about the need for surgery and the surgical strategy for ASD is limited. Findings from this survey highlight the need for comprehensive classifications for ASD, higher-level studies including randomized trials to set guidelines and lessen the variability in clinical practices, which would then hopefully lead to improved outcomes.

Study design This was a retrospective cohort study. Objective The objective of this study was to compare implant-related complications between mixed-metal and same-metal rod-screw constructs in patients who underwent posterior fusion for adult spinal deformity. Summary of background data Contact between dissimilar metals is discouraged due to potential for galvanic corrosion, increasing the risk for metal toxicity, infection, and implant failure. In spine surgery, titanium (Ti) screws are most commonly used, but Ti rods are notch sensitive and likely more susceptible to fracture after contouring for deformity constructs. Cobalt chrome (CC) and stainless steel (SS) rods may be suitable alternatives. No studies have yet evaluated implant-related complications among mixed-metal constructs (SS or CC rods with Ti screws). Methods Adults with spinal deformity who underwent at least 5-level thoracic and/or lumbar posterior fusion or 3-column osteotomy between January 2013 and May 2015 were reviewed, excluding neuromuscular deformity, tumor, acute trauma or infection. Implant-related complications included pseudarthrosis, proximal junctional kyphosis, hardware failure (rod fracture, screw pullout or haloing), symptomatic hardware, and infection. Results A total of 61 cases met inclusion criteria: 24 patients received Ti rods with Ti screws (Ti-Ti, 39%), 31 SS rods (SS-Ti, 51%), and 6 CC rods (CC-Ti, 9.8%). Median follow-up was 37-42 months for all groups. Because of the limited number of cases, the CC-Ti group was not included in statistical analyses. There were no differences between Ti-Ti and SS-Ti groups with regard to age, body mass index, or smokers. Implant-related complications did not differ between the Ti-Ti and SS-Ti groups (P=0.080). Among the Ti-Ti group, there were 15 implant-related complications (63%). In the SS-Ti group, there were 12 implant-related complications (39%). There were 3 implant-related complications in the CC-Ti group (50%). Conclusion We found no evidence that combining Ti screws with SS rods increases the risk for implant-related complications.

Background With the use of constrained condylar knee (CCK) prostheses, dislocation of the knee following total knee arthroplasty (TKA) with valgus deformity is rare. In our practice with such patients, however, an abnormally high dislocation rate was noted. It appeared to be associated with the extent of soft-tissue release which varied among surgeons following different sequences of release. We asked in CCK TKA with valgus deformity is releasing both the lateral collateral ligament (LCL) and popliteus tendon (PT) associated with the occurrence of dislocation. Methods This is a case-control study of consecutive patients with valgus deformity who underwent primary CCK TKA between July 2008 and October 2015. The cases and controls were patients with and without postoperative dislocation of the knee, respectively. The extent of the release of lateral soft-tissue structures was compared between the two groups. Other patient characteristics including age, body mass index, pre- and post-operative valgus deformity, preoperative flexion-contracture, and height of the polyethylene insert were compared as well to reduce confounding. Results Forty-three consecutive patients with a minimum 2-year follow-up were enrolled. 9.3% (4/43) of the patients had postoperative dislocation of the knee. While the dislocated patients did not significantly differ from the controls on most characteristics, they were more likely to have both the LCL and PT released together during the surgery [100% (4/4) vs. 2.6% (1/39), P

BACKGROUND CONTEXT Exposure to surgical smoke remains a potential occupational health concern to spine operating room personnel. Using a smoke evacuator (local exhaust ventilation) is currently regarded as a primary means of protection, yet few studies have evaluated its utility in actual surgeries. OBJECTIVE To examine the utility of two common types of local smoke evacuators, a para incisional evacuator and a smoke evacuation pencil, in reducing surgical smoke exposure in spine surgery. STUDY DESIGN A prospective self-controlled study. PATIENT SAMPLE After the pre-estimation of sample size, 51 consecutive spine surgeries (25 and 26 patients using the para incisional smoke evacuator and the smoke evacuation pencil, respectively) were enrolled between February 2018 and March 2019. OUTCOME MEASURES Two outcome measures were used to evaluate the level of surgical smoke exposure, which was defined as the concentration of ultrafine smoke particles in the air (number of particles per cm3, ppc) around the operating table: (a) the average smoke level was the arithmetic mean of all measurements recorded during the surgery; and (b) the peak smoke level was the highest measurement recorded. METHODS Consecutive surgeries that involved bilateral symmetrical surgical exposure of the spine via a posterior midline incision were evaluated. Cauterized smoke was evacuated by two smoke evacuators: a “para incisional evacuator,” which used a flat broad suction pad positioned immediately adjacent to the incision (25 patients), and a “surgical smoke evacuation pencil” which is an incorporated part of the electrocautery (26 patients). The level of smoke exposure was measured separately when surgically exposing the two sides of the spine: starting with one side (determined randomly) with the smoke evacuator being turned on and, then, the other side with the smoke evacuator off. The results were compared between the two sides. RESULTS The para incisional smoke evacuator significantly reduced the average smoke level by an average of 59.7% (287 [interquartile range {IQR}: 126, 526] vs. 1,177 [IQR: 395, 2,702], p CONCLUSIONS This study provides evidence supporting the utility of local smoke evacuation in reducing surgical smoke exposure in spine surgery. Such technology may help to improve the occupational health protection for spine operating room workers.

Aims Patients may present with concurrent symptomatic osteoarthritis (OA) of the hip and degenerative disorders of the lumbar spine, with surgical treatment being indicated for both. Whether arthroplasty of the hip or spinal surgery should be performed first remains uncertain. Materials and Methods Clinical scenarios were devised for a survey asking the preferred order of surgery and the rationale for this decision for five fictional patients with both OA of the hip and degenerative lumbar disorders. These were symptomatic OA of the hip and: 1) lumbar spinal stenosis with neurological claudication; 2) lumbar degenerative spondylolisthesis with leg pain; 3) lumbar disc herniation with leg weakness; 4) lumbar scoliosis with back pain; and 5) thoracolumbar disc herniation with myelopathy. This survey was sent to 110 members of The Hip Society and 101 members of the Scoliosis Research Society. The choices of the surgeons were compared among scenarios and between surgical specialties using the chi-squared test. The free-text comments were analyzed using text-mining. Results Responses were received from 51 hip surgeons (46%) and 37 spine surgeons (37%). The percentages of hip surgeons recommending ‘hip first’ differed significantly among scenarios: 59% for scenario 1; 73% for scenario 2; 47% for scenario 3; 47% for scenario 4; and 10% for scenario 5 (p < 0.001). The percentages of spine surgeons recommending ‘hip first’ were 49% for scenario 1; 70% for scenario 2; 19% for scenario 3; 78% for scenario 4; and 0% for scenario 5. There were significant differences between the groups for scenarios 3 (more hip surgeons recommended ‘hip first’; p = 0.012) and 4 (more hip surgeons recommended ‘spine first’; p = 0.006). Conclusion In patients with coexistent OA of the hip and degenerative disorders of the spine, the question of ‘hip or spinal surgery first’ elicits relatively consistent answers in some clinical scenarios, but remains controversial in others, even for experienced surgeons. The nature of neurological symptoms can influence surgeons’ decision-making. Cite this article: Bone Joint J 2019;101-B(6 Supple B):37–44.

Increased out-of-pocket costs have led to patients bearing more of the financial burden for their care. Previous work has shown that financial burden and distress can affect outcomes, symptoms, satisfaction, and adherence to treatment. We asked the following questions: (1) Does patients' financial distress correlate with disability in patients with nonacute orthopaedic conditions? (2) Do patient demographic factors affect this correlation?We conducted a cross-sectional, observational study of new patients presenting to a multispecialty orthopaedic clinic with a nonacute orthopaedic complication. Patients completed a demographics questionnaire, the InCharge Financial Distress/Financial Well-Being Scale, and the Health Assessment Questionnaire Disability Index. Statistical analysis was done using Pearson's correlation.The mean score for financial distress was 4.10 (SD, 2.09; scale 1 [low distress] to 10 [high distress]; range, 1.13 to 10.0), and the mean disability score was 0.54 (SD, 0.65; scale 0 to 3; range, 0 to 2.75). A moderate positive correlation exists between financial distress and disability (r = 0.43; P0.01). Financial distress and disability were highest for poor, uneducated, Medicare patients.A moderate correlation exists between financial distress and disability in patients with nonacute orthopaedic conditions, particularly in patients with low socioeconomic status. Orthopaedic surgeons may benefit from identifying patients in financial distress and discussing the cost of treatment because of its association with disability and potentially inferior outcomes. Further investigation is needed to test whether decreasing financial distress decreases disability.Level III prospective cohort.

Study design A cross-sectional survey of orthopedic spine surgery fellowship directors in the United States. Objective The aim of this study was to investigate whether consensus exists with respect to spine-related adverse events and certain hospital-acquired conditions (HACs) or "never events." Summary of background data As part of a broad effort to improve health care outcomes, providers are no longer reimbursed for HACs, which are deemed avoidable. Although some HACs are unquestionably preventable with proper quality control measures, research suggests that even scrupulous adherence to evidence-based guidelines cannot eliminate others. Methods Surveys were distributed via email and post. Participants rated 27 HACs and selected spine-specific events on an ordinal scale. Interobserver reliability was assessed among all 46 spine directors (respondents) using the intraclass correlation coefficient (ICC), based on a two-way random effects model, assuming that the participants were a representative population sample of spine surgeons. Multivariable linear regression analyses were performed on each of the 27 complications to identify potential demographic factors that could be associated with variation among respondents in their ratings of "avoidable" to "unavoidable." Results Forty-six fellowship directors responded, of whom 98% were orthopedic spine surgeons. The majority (80.4%) of respondents had greater than 10 years' experience as a spine surgeon, and 66.7% had an annual surgical volume >201 cases. The multivariable linear regression analyses found that demographic factors were not predictive of the directors' ratings. The complications thought to be completely avoidable (median scores 1) included "Incompatible blood," "Retained foreign object," and "Wrong level surgery." The HAC considered least avoidable was "Site infection with risk factors" (median score 8). Among 17 spine-specific complications, "L4-L5 disc re-herniation within 3 months" (median score 9) was considered least avoidable. Conclusion This survey suggests that orthopedic spine surgeons consider most "never events" neither avoidable nor unavoidable. There is strong consensus only about the HACs resulting from obvious medical error. Level of evidence 4.

Overgrowth of epidural fat, known as spinal epidural lipomatosis (SEL), can cause symptomatic compression of the spinal cord, conus medullaris, or cauda equina. Suggested predisposing factors such as obesity, steroid use, and diabetes mellitus have been based on a few reported cases, many of which were not surgically confirmed. There is a paucity of epidemiological data in surgically confirmed cases for this disorder. The purpose of this independently reviewed, retrospective, matched cohort analysis was to compare the demographics and incidence of comorbidities of patients who underwent lumbar decompression for SEL vs degenerative stenosis without SEL. Two surgeons' databases were reviewed to identify patients older than 18 years who underwent decompression surgery for magnetic resonance imaging–verified, symptomatic lumbar SEL. A matched control group comprised an equal number of patients with degenerative stenosis (n=14). Demographic data, body mass index, symptom type/duration, comorbidities, complications, treatment history, and associated pathology were collected from medical records. Previously suggested risk factors, such as obesity, endocrinopathy, and epidural steroid injections, were not significantly different between the SEL and control groups. Furthermore, there were no differences in operative times, complications, or blood loss. The only noted difference between the 2 groups was the preoperative duration of symptoms, on average double in patients with SEL. This series represents the largest of its kind reported to date. Because symptom duration was the only difference noted, it is postulated to be the result of lack of awareness of SEL. Future prospective study in a larger group of patients is warranted. [ Orthopedics. 2016; 39(3):163–168.]

Background Context Neuroforaminal stenosis is one of the key factors causing clinical symptoms in patients with cervical radiculopathy. Previous quantitative studies on the neuroforaminal dimensions have focused on measurements in a static position. Little is known about dimensional changes of the neuroforamina in the cervical spine during functional dynamic neck motion under physiological loading conditions. Purpose This study aimed to investigate the in vivo dimensional changes of the neuroforamina in human cervical spine (C3–C7) during dynamic flexion-extension neck motion. Study Design A case-control study was carried out. Methods Ten asymptomatic subjects were recruited for this study. The cervical spine of each subject underwent magnetic resonance image scanning for construction of three-dimensional (3-D) vertebrae models from C3 to C7. The cervical spine was then imaged using a dual fluoroscopic system while the subject performed a dynamic flexion-extension neck motion in a sitting position. The 3-D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral motion. The dimensions (area, height, and width) were measured for each cervical neuroforamen (C3/C4, C4/C5, C5/C6, and C6/C7) in the following functional positions: neutral position, maximal flexion, and maximal extension. Repeated measures analysis of variance and post hoc analysis were used to examine the differences between levels and positions. Results Compared with the neutral position, almost all dimensional parameters (area, height, and width) of the subaxial cervical neuroforamina decreased in extension and increased in flexion, except the neuroforaminal area at C5/C6 (p=.07), and the neuroforaminal height at C6/C7 (p=.05) remained relatively constant from neutral to extension. When comparisons of the overall change fromextension to flexion were made between segments, the overall changes of the neuroforaminal area and height revealed no significant differences between segments, and the width overall change of the upper levels (C3/C4 and C4/C5) was significantly greater than the lower levels (C5/C6 and C6/C7) (p Conclusions The dimensional changes of the cervical neuroforamina showed segment-dependent characteristics during the dynamic flexion-extension. These data may have implications for diagnosis and treatment of patients with cervical radiculopathy.

Retrospective review and prospective validation study.To develop a classification system of lumbar lateral listhesis that suggests different likelihoods of having radiculopathy in adult scoliosis.The association of lumbar lateral listhesis with radiculopathy remains uncertain.A retrospective cohort of patients with adult scoliosis enrolled from 2011 to 2015 was studied to develop a classification system of lateral listhesis that can stratify the likelihood of having radiculopathy. Four radiological aspects of lateral listhesis, including Nash and Moe vertebral rotation, L4-L5 lateral listhesis, the number of consecutive listheses, and the presence of a contralateral lateral listhesis at the thoracolumbar junction above a caudal listhesis, were evaluated on radiographs. Their associations with the presence of radicular leg pain were evaluated using multivariable logistic regression. The classification system of lateral listhesis was thus developed using the most influential radiological factors and then validated in a prospective cohort from 2016 to 2017.The retrospective cohort included 189 patients. Vertebral rotation is more than or equal to grade 2 (odds ratio [OR] = 9.45, 95% confidence interval [CI]: 4.07-25.14) and L4-5 listhesis (OR = 4.56, 95%CI: 1.85-12.35) were the two most influential listhesis factors associated with radiculopathy. The classification system of lateral listhesis was thus built based on the combinations of their respective presence: Type 0, 1, 2, 3 were defined as not having listhesis at all, none of the two factors present, one of the two presents, and both present, respectively. This classification significantly stratified the probability of radiculopathy, in both the retrospective cohort (0%, 6.4%, 33.8%, and 68.4% in Type 0, 1, 2, and 3, respectively; P 0.001) and a prospective cohort of 105 patients (0%, 16.7%, 46.9%, and 72.7%; P 0.001).Lumbar lateral listhesis is associated with the presence of radiculopathy in adult scoliosis. Types 2 and 3 lateral listhesis on radiographs may alert surgeons treating patients with spinal deformity.2.

BACKGROUND CONTEXT It is recognized that radiological parameters of type 2 dens fractures, including displacement and angulation, are predictive of treatment outcomes and are used to guide surgical decision-making. The reproducibility of such measurements, therefore, is of critical importance. Past literature has shown poor interobserver reliability for both displacement and angulation measurements of type 2 dens fractures. Since such studies however, various advancements of radiological review systems and measurement tools have evolved to potentially improve such measurements. PURPOSE To re-examine the inter-rater reliability of measuring displacement and angulation of type 2 dens fractures using modern radiological review systems. Besides quantitative measurements, the reliability of raters in identifying diagnostic classifications based on translational and angulational displacement was also examined. STUDY DESIGN Radiographic measurement reliability and agreement study. PATIENT SAMPLE Thirty-seven patients seen at a single institution between 2002 and 2017 with primary diagnosis of acute type 2 dens fracture with complete computed tomography (CT) imaging. OUTCOME MEASURES Radiological measurements included displacement and angulation. Diagnostic classifications based on consensus-based clinical cutoff points were also recorded. METHODS Measurements were performed by five surgeons with varying years of experience in spine surgery using the hospital's electronic medical record radiological measuring tools. The radiological measurements included displacement and angulation. Diagnostic classifications based on consensus-based clinical cutoff points were also recorded. Each rater received a graphic demonstration of the measurement methods, but had the autonomy to select a best cut from the sagittal CT to measure. All raters were blinded to patient information. RESULTS Measurements for displacement and angulation among the five raters demonstrated “excellent” reliability. Intra-rater reliability was also “excellent” in measuring displacement and angulation. The reliability of diagnostic classification of displacement (above vs. below 5 mm), was found to be “very good” among the raters. The reliability of diagnostic classification of angulation (above vs. below 11°) demonstrated “good” reliability. CONCLUSIONS Advancement of radiological review systems, including review tools and embedded image processing software, has facilitated more reliable measurements for type 2 odontoid fractures.

This is a retrospective cohort study.To evaluate the long-term outcomes of selective one- to two-level anterior lumbar interbody fusions (ALIFs) in the lower lumbar spine versus continued nonsurgical management.Low back pain associated with lumbar intervertebral disc degeneration is common with substantial economic impact, yet treatment remains controversial. Surgical fusion has previously provided mixed results with limited durable improvement of pain and function.Seventy-five patients with one or two levels of symptomatic Pfirrmann grades 3 to 5 disc degeneration from L3-S1 were identified. All patients had failed at least 6 months of nonsurgical treatment. Forty-two patients underwent one- or two-level ALIFs; 33 continued multimodal nonsurgical care. Patients were evaluated radiographically and the visual analog pain scale (VAS), Oswestry Disability Index (ODI), EuroQol five dimensions (EQ-5D), and Patient-Reported Outcomes Measurement Information System scores for pain interference, pain intensity, and anxiety. As-treated analysis was performed to evaluate outcomes at a mean follow-up of 7.4 years (range: 2.5-12).There were no differences in pretreatment demographics or nonsurgical therapy utilization between study arms. At final follow-up, the surgical arm demonstrated lower VAS, ODI, EQ-5D, and Patient-Reported Outcomes Measurement Information System pain intensity scores versus the nonsurgical arm. VAS and ODI scores improved 52.3% and 51.1% in the surgical arm, respectively, versus 15.8% and -0.8% in the nonsurgical arm. Single-level fusions demonstrated improved outcomes versus two-level fusions. The pseudarthrosis rate was 6.5%, with one patient undergoing reoperation. Asymptomatic adjacent segment degeneration was identified in 11.9% of patients.Selective ALIF limited to one or two levels in the lower lumbar spine provided improved pain and function when compared with continued nonsurgical care. ALIF may be a safe and effective treatment for low back pain associated with disc degeneration in select patients who fail nonsurgical management.3.

Study design Prospective cohort study in consecutive patients. Objective To investigate and compare the use of 2 diagnostic modalities in the evaluation of stability in lumbar spondylolisthesis. Summary of background data Evaluating potential instability in lumbar spondylolisthesis is significant to its management. Lateral lumbar flexion-extension (FE) radiograph is frequently obtained on the basis of a thought that this forward-backward movement can actually describe hypermobility at the listhetic segment. However, simply comparing standard upright lumbar lateral radiograph (U) with a supine sagittal magnetic resonance image (S) (combined, US), something typically conducted for patients with lumbar spondylolisthesis, may also be used. Methods This prospective study included a cohort of 68 consecutive patients with lumbar spondylolisthesis seen in the outpatient clinic of a single hospital. The mobility observed in US was compared with that observed in FE. The ability to identify "instability" using US was compared with that using FE. In addition, the relationships between mobility determined using FE or US and sex, age, height, weight, body mass index, primary symptom (with or without back pain), nature of spondylolisthesis (degenerative or isthmic), listhetic segment, slippage grade, and focal disc height were examined. Results Overall, the mobility in US was significantly higher than that in FE (7.68 ± 5.34% vs. 4.90 ± 3.82%, t =-3.545, P = 0.001). The ability to identify "instability" on the basis of US was improved compared with that obtained using FE. Female patients demonstrated higher mobility in FE than male patients to a significant degree. Back pain, isthmic spondylolisthesis, and slippage grade also showed some relevance with mobility but without statistical significance. Conclusion US may offer an easily available, alternative diagnostic modality in lumbar spondylolisthesis, with the potential of reducing both radiation exposure and costs. Further studies should focus on its influence in clinical decision making. Level of evidence 2.

Allogeneic blood transfusions have an immunomodulating effect, and the previous studies in other fields of medicine demonstrated an increased risk of infections after administration of allogeneic blood transfusions.Our primary null hypothesis is that exposure to allogeneic blood transfusion in patients undergoing lumbar spine surgery is not associated with postoperative infections after controlling for patient and treatment characteristics. Second, we assessed if there was a dose-response relationship per unit of blood transfused.This is a retrospective cohort study from a tertiary care spine referral center.A total of 3,721 patients underwent laminectomy and/or arthrodesis of the lumbar spine.Postoperative infections, pneumonia, endocarditis, meningitis, urinary tract infection, central venous line infection, surgical site infection, and sepsis, within 90 days after lumbar spine surgery were included.Multivariable logistic regression analyses were used to assess the relationship of perioperative allogeneic blood transfusion with specific and overall postoperative infections accounting for age, duration of surgery, duration of hospital stay, comorbidity status, preoperative hemoglobin, sex, type of operation, multilevel treatment, operative approach, and year of surgery.The adjusted odds ratio for exposure to allogeneic blood transfusion from multivariable logistic regression analysis was 2.6 for any postoperative infection (95% confidence interval [CI]: 1.7-3.9, p.001); 2.2 for urinary tract infections (95% CI: 1.3-3.9, p=.004); 2.3 for pneumonia (95% CI: 0.96-5.3, p=.062); and 2.6 for surgical site infection requiring incision and drainage (95% CI: 1.3-5.3, p=.007). Secondary analyses demonstrated no dose-response relationship between the number of blood units transfused and any of the postoperative infections. Because of the low number of endocarditis (1 case, 0.031%), meningitis (1 case, 0.031%), central venous line infection (1 case, 0.031%), and sepsis (14 cases, 0.43%), we abstained from multivariable analysis.Conscious of the limitations of this retrospective study, our data suggest an increased risk of surgical site infection, urinary tract infection, and overall postoperative infections, but not pneumonia, after exposure to allogeneic blood transfusion in patients undergoing lumbar spine surgery. These findings should be taken into account when considering blood transfusion and developing transfusion policies for patients undergoing lumbar spine procedures.

Value-based healthcare models rely on quality measures to evaluate the efficacy of healthcare delivery and to identify areas for improvement. Quality measure research in other areas of health care has generally shown that there is a limited number of available quality measures and that those that exist disproportionately focus on processes as opposed to outcomes. The purpose of this study was to assess the current state of quality measures and candidate quality measures in spine surgery.(1) How many quality measures and candidate quality measures are currently available? (2) According to Donabedian domains and National Quality Strategy (NQS) priorities, what aspects or domains of care do the present quality measures and candidate quality measures represent?We systematically reviewed the National Quality Forum, the Agency for Healthcare Research and Quality, and the Physician Quality Reporting System for quality measures relevant to spine surgery. A systematic search for candidate quality measures was also performed using MEDLINE/PubMed and Embase as well as publications from the American Academy of Orthopaedic Surgeons, Congress of Neurological Surgeons, and the North American Spine Society. Clinical practice guidelines were included as candidate quality measures if their development was in accordance with Institute of Medicine criteria for the development of clinical practice guidelines, they were based on consistent clinical evidence including at least one Level I study, and they carried the strongest possible recommendation by the developing body. Quality measures and candidate quality measures were then pooled for analysis and categorized by clinical focus, NQS priority, and Donabedian domain. Our initial search yielded a total of 3940 articles, clinical practice guidelines, and quality measures, 74 of which met criteria for inclusion in this study.Of the 74 measures studied, 29 (39%) were quality measures and 45 (61%) were candidate quality measures. Fifty of 74 (68%) were specific to the care of the spine, and 24 of 74 (32%) were related to the general care of spine patients. The majority of the spine-specific measures were process measures (45 [90%]) and focused on the NQS priority of "Effective Clinical Care" (44 [88%]). The majority of the general care measures were also process measures (14 [58%]), the highest portion of which focused on the NQS priority of "Patient Safety" (10 [42%]).Given the large number of pathologies treated by spine surgeons, the limited number of available quality measures and candidate quality measures in spine surgery is inadequate to support the transition to a value-based care model. Additionally, current measures disproportionately focus on certain aspects or domains of care, which may hinder the ability to appropriately judge an episode of care, extract usable data, and improve quality. Physicians can steward the creation of meaningful quality measures by participating in clinical practice guideline development, assisting with the creation and submission of formal quality measures, and conducting the high-quality research on which effective guidelines and quality measures depend.

Retrospective cohort study.Assess differences between staged (≤3 days) and same-day surgery in perioperative factors, radiographic measures, and complications.Surgical adult spinal deformity correction may require combined anterior and posterior approaches. To modulate risk, some surgeons perform surgery that is expected to be longer and/or more complex in two stages. Prior studies comparing staged (≥7 days) and same-day surgery demonstrated mixed results and none have examined results with shorter staging intervals.Retrospective review of adults undergoing combined anterior/posterior approaches for spinal deformity over a 3-year period at a single institution (n=92). Univariate differences between staged and same-day surgery were assessed with chi-squared, Fisher exact, and Mann-Whitney U tests. Generalized estimating equations assessed whether differences in perioperative outcomes between groups remained after adjusting for differences in demographic and surgical characteristics.In univariate analyses, staged surgery was associated with a length of stay (LOS) 3 days longer than same-day surgery (9.2 vs. 6.3 days, p.001), and greater operative time, blood loss, transfusion requirement, and days in intensive care unit (p.001 for each). Staged surgery had a higher rate of thrombotic events (p = .011) but did not differ in readmission rates or other complications. Radiographically, improvements in Cobb angle (average 13° vs. 17°, p = .028), lumbar lordosis (average 14° vs. 23°, p = .019), and PI-LL mismatch (average 10° vs. 2° p = .018) were greater for staged surgery, likely related to more extensive use of osteotomies in the staged group. After risk adjustment, taking into account the procedural specifics including longer fusion constructs and greater number of osteotomies, LOS no longer differed between staged and same-day surgery; however, the total operative time was 98 minutes longer for staged surgery (p.001). Differences in blood loss between groups was accounted for by differences in operative time and patient and surgical characteristics.Although univariate analysis of our results were in accordance with previously published works, multivariate analysis allowing individual case risk adjustment revealed that LOS was not significantly increased in the staged group as reported in previous studies. There was no difference in infection rates as previously described but an increase in thrombotic events was observed.Level III.

Evidence-based systematic review.To define the optimal treatment of fractures involving the C2 body, including those with concomitant injuries, based upon a systematic review of the literature.Axis body fractures have customarily been treated nonoperatively, but there are some injuries that may require operative intervention. High-quality literature is sparse and there are few class I or class II studies to guide treatment decisions.A literature search was conducted using PubMed (MEDLINE), Cochrane Central Register of Controlled Trials, and Scopus (EMBASE, MEDLINE, COMPENDEX). The quality of literature was rated according to a grading tool developed by the Center for Evidence-based Medicine. Operative and nonoperative treatment of axis body fractures were compared using fracture bony union as the primary outcome measure. As risk factors for nonunion were not consistently reported, cases were analyzed individually.The literature search identified 62 studies, of which 10 were case reports which were excluded from the analysis. A total of 920 patients from 52 studies were included. The overall bony union rate for all axis body fractures was 91%. Although the majority of fractures were treated nonoperatively, there has been an increasing trend toward operative intervention for Benzel type III (transverse) axis body fractures. Nearly 76% of axis body fractures were classified as type III fractures, of which 88% united successfully. Nearly all Benzel type I and type II axis body fractures were successfully treated nonoperatively. The risk factors for nonunion included: a higher degree of subluxation, fracture displacement, comminution, concurrent injuries, delay in treatment, and older age.High rates for fracture union are reported in the literature for axis body fractures with nonoperative treatment. High-quality prospective studies are required to develop consensus as to which C2 body fractures require operative fixation.

OBJECTIVEThis study aimed to compare the clinical results of using posterior fixation and fusion with or without anterior decompression to treat os odontoideum with atlantoaxial dislocation.METHODSTwenty-five consecutive patients with os odontoideum were included in this study. Sixteen patients with reducible atlantoaxial dislocation were treated by single-level posterior fusion and stabilization; the other 9 were treated with posterior fusion and stabilization combined with transoral decompression. Pre- and postoperative CT scans and MR images were obtained.RESULTSTwenty-four patients were followed for 24–54 months (average 36.5 months). Postoperative CT scans indicated that all pedicle screws were placed satisfactorily except in 2 cases, in which the screws slightly penetrated the transverse foramen. Postoperative MR images demonstrated that sufficient decompression of the spinal cord was obtained in all patients. Complications included 1 case each of pedicle screw breakage, pharynx ulcer, and persistent pharynx discomfort. Statistical analysis of all cases revealed that mean Japanese Orthopaedic Association scores improved from a preoperative score of 10.2 (range 7–13) to a postoperative score of 15.6 (range 11–18).CONCLUSIONSPatients who have os odontoideum with a reducible atlantoaxial dislocation can be effectively treated with single-level posterior fusion and stabilization. Combined transoral decompression and posterior fusion and stabilization is recommended for those with irreducible atlantoaxial dislocation.

While abnormal loading is widely believed to cause cervical spine disc diseases, in vivo cervical disc deformation during dynamic neck motion has not been well delineated. This study investigated the range of cervical disc deformation during an in vivo functional flexion–extension of the neck. Ten asymptomatic human subjects were tested using a combined dual fluoroscopic imaging system (DFIS) and magnetic resonance imaging (MRI)-based three-dimensional (3D) modeling technique. Overall disc deformation was determined using the changes of the space geometry between upper and lower endplates of each intervertebral segment (C3/4, C4/5, C5/6, and C6/7). Five points (anterior, center, posterior, left, and right) of each disc were analyzed to examine the disc deformation distributions. The data indicated that between the functional maximum flexion and extension of the neck, the anterior points of the discs experienced large changes of distraction/compression deformation and shear deformation. The higher level discs experienced higher ranges of disc deformation. No significant difference was found in deformation ranges at posterior points of all the discs. The data indicated that the range of disc deformation is disc level dependent and the anterior region experienced larger changes of deformation than the center and posterior regions, except for the C6/7 disc. The data obtained from this study could serve as baseline knowledge for the understanding of the cervical spine disc biomechanics and for investigation of the biomechanical etiology of disc diseases. These data could also provide insights for development of motion preservation surgeries for cervical spine.

STUDY DESIGN Cross-sectional study reviewing 62 magnetic resonance imaging or computed tomography scans from consecutive adult patients with scoliotic spinal deformity in the thoracolumbar spine. OBJECTIVE To investigate the variation in anatomic position of retroperitoneal vessels in relationship to curve direction, location, magnitude, and axial rotation of curves in adult scoliosis. SUMMARY OF BACKGROUND DATA The minimally invasive lateral approach to the thoracolumbar spine avoids manipulation of abdominal and retroperitoneal structures and decreases risk of injury to paraspinal musculature. In adult patients with scoliosis, the varying anatomic relationship between retroperitoneal vessels and intervertebral disk spaces can increase the risk of vascular injury. MATERIALS AND METHODS Axial images were used to measure the anterior-posterior diameter of the inferior vertebral endplate with respect to the disk space perpendicular to the widest length of the disk. The overlap of the retroperitoneal vessels with the endplate were measured at the cephalad end vertebra, apex, and caudad end vertebra of each curve. Overlap and accessible disk space for individual disk spaces were also measured. RESULTS There was a significant difference in percentage overlap of the apex and cephalad vertebral endplate and inferior vena cava in right versus left-sided curves (P=0.002). Overlap between the inferior vertebral endplate and inferior vena cava at the cephalad, apex, and caudad end of the curve was significantly different between thoracolumbar and lumbar curves (P

STUDY DESIGN Retrospective radiographic study. OBJECTIVE To radiographically evaluate sagittal plane profile and fusion rates of polyetheretherketone (PEEK) cages versus femoral ring allografts (FRAs) in patients with adult spinal deformity fused to the sacrum. SUMMARY OF BACKGROUND DATA FRAs have been widely used in various degenerative lumbar spine disorders and in adult deformity to achieve interbody fusions with promising results. PEEK cages have gained increasing popularity of late; however, there is little documentation to the radiographic comparisons between PEEK cages and FRAs used in patients with adult spine deformity treated with long fusions to the sacrum. METHODS From March 2006 to February 2010, we analyzed 48 patients (mean age, 56.3±13.9 y) of 61 consecutive adult patients with global coronal and sagittal adult spine deformities who underwent first stage ALIF using PEEK cages or FRAs at L4-L5, L5-S1 segments followed by long (>6 levels) posterior instrumentation. PEEK cages and FRAs were used randomly according to surgeon's preference. Two independent observers retrospectively evaluated preoperative and postoperative disk height, foraminal height, segmental lordosis, and the interbody fusion rates at different postoperative intervals. RESULTS Both PEEK cages and FRAs significantly (P

Study design Retrospective medical record review. Objective The purpose of this study was to determine whether a history of abdominal/pelvic surgery confers an increased risk of retroperitoneal anterior approach-related complications when undergoing anterior lumbar interbody fusion. Summary of background data As anterior lumbar interbody fusion gains popularity, both anterior retroperitoneal approach have become increasingly used. Methods The records of 263 patients, who underwent infraumbilical retroperitoneal approach to the anterior aspect of the lower lumbar spine for a degenerative spine condition between 2007 and 2011 were retrospectively reviewed. Patient's demographics, risk factors, preoperative diagnosis, surgical history, level of the anterior fusion, and perioperative complications were collected. Anterior retroperitoneal approach to the spine was carried out by a single general surgeon. Results Ninety-seven patients (37%) developed at least 1 complication. Forty-nine percent of patients with a history of abdominal surgery developed a postoperative complication compared with 28% of patients without such history (RR = 1.747, P≤ 0.001). After controlling for other factors such as age, sex, body mass index, diagnostic groups, and preoperative comorbidities (hypertension, diabetes, and smoking status), these differences remained statistically significant. When each type of complication was considered separately, there was a statistically significant difference in the incidence of general complications (RR = 2.384, P = 0.007), instrumentation-related complications (RR = 2.954, P = 0.010), and complications related to the anterior approach (RR = 1.797, P = 0.021). Conclusion Anterior lumbar interbody fusion via a midline incision and a retroperitoneal approach was associated with 37% overall rate of complication. Patients with a history of abdominal or pelvic surgery are at a higher risk of developing general, instrumentation, and anterior approach-related complications.

Many studies have reported on the segmental motion range of the lumbar spine using various in vitro and in vivo experimental designs. However, the in vivo weightbearing dynamic motion characteristics of the L4–5 and L5–S1 motion segments are still not clearly described in literature. This study investigated in vivo motion of the lumbar spine during a weight-lifting activity. Ten asymptomatic subjects (M/F: 5/5; age: 40–60 years) were recruited. The lumbar segment of each subject was MRI-scanned to construct 3D models of the L2–S1 vertebrae. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed a weight-lifting activity from a lumbar flexion position (45°) to maximal extension position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral positions along the motion path. The relative translations and rotations of each motion segment were analyzed. All vertebral motion segments, L2–3, L3–4, L4–5 and L5–S1, rotated similarly during the lifting motion. L4–5 showed the largest anterior-posterior (AP) translation with 2.9 ± 1.5 mm and was significantly larger than L5–S1 (p

Objective The aim of this study is to evaluate prospectively the efficacy of caudal epidural steroid injection (CESI) and transforaminal epidural steroid injection (TFESI) in lumbar spinal stenosis patients with sciatic pain. Design Prospective clinical study. Setting and Patients Thirty-one patients (average age 62 years) from two hospitals, with single dermotomal distribution of sciatic pain due to spinal stenosis were included in the study. Interventions Patients underwent epidural steroid injections done by the same injectionist. Eleven patients from one hospital were included in the CESI group, while the TFESI group consisted of 20 comparable patients from the second site. Outcome Measures Primary outcome measure was the complete relief or at least 50% reduction of pain (visual analog scale [VAS]) at 6 months postinjection. Secondary outcome measures were the improvement of function (of at least 15 points of Oswestry Disability Index [ODI]) at 6 months and the changes of VAS and ODI and at 2 weeks, at 3 months, and at 6 months postinjection. Results A significantly greater number of stenosis patients showed pain relief at 6 months postinjection with TFSI (90%) than with CESI (54.54%). All patients with TFSI showed improvement of function at 6 months while only three (27.27%) patients with caudal epidural improved functionally. Out of the total 31 patients, two patients from group A underwent a second CESI at 15 days postinjection and decompressive spine surgery between 3 and 6 months postinjection. Conclusions The effectiveness of transforaminal steroid injection for the stenosis patients with sciatica was superior to caudal at 6 months postinjection.

Knowledge of in vivo human lumbar loading is critical for understanding the lumbar function and for improving surgical treatments of lumbar pathology. Although numerous experimental measurements and computational simulations have been reported, non-invasive determination of in vivo spinal disc loads is still a challenge in biomedical engineering. The object of the study is to investigate the in vivo human lumbar disc loads using a subject-specific and kinematic driven finite element approach.Three dimensional lumbar spine models of three living subjects were created using MR images. Finite element model of the L3-4 disc was built for each subject. The endplate kinematics of the L3-4 segment of each subject during a dynamic weight lifting extension was determined using a dual fluoroscopic imaging technique. The endplate kinematics was used as displacement boundary conditions to calculate the in-vivo disc forces and moments during the weight lifting activity.During the weight lifting extension, the L3-4 disc experienced maximum shear load of about 230 N or 0.34 bodyweight at the flexion position and maximum compressive load of 1500 N or 2.28 bodyweight at the upright position. The disc experienced a primary flexion-extension moment during the motion which reached a maximum of 4.2 Nm at upright position with stretched arms holding the weight.This study provided quantitative data on in vivo disc loading that could help understand intrinsic biomechanics of the spine and improve surgical treatment of pathological discs using fusion or arthroplasty techniques.

Background context Traumatic fractures of the spine are most common at the thoracolumbar junction and can be a source of great disability. Purpose To review the most current information regarding the pathophysiology, injury pattern, treatment options, and outcomes. Study design Literature review. Methods Relevant articles, textbook chapters, and abstracts covering thoracolumbar spine fractures with and without neurologic deficit from 1960 to the present were reviewed. Results The thoracolumbar spine represents a unique system from a skeletal as well as neurological standpoint. The rigid rib-bearing thoracic spine articulates with the more mobile lumbar spine at the thoracolumbar junction (T10 - L2), the site of most fractures. A complete examination includes a careful neurologic examination of both motor and sensory systems. CT scans best describe bony detail while MRI is most efficient at describing soft tissues and neurological structures. The most recent classification system is that of the new Thoracolumbar Injury Classification and Severity Score. The different fracture types include compression fractures, burst fractures - both stable and unstable -, flexion-distraction injuries and fracture dislocations. Their treatment, both operative and non-operative depends on the degree of bony compromise, neurological involvement, and the integrity of the posterior ligamentous complex. Minimally invasive approaches to the care of thoracolumbar injuries have become more popular, thus, the evidence regarding their efficacy is presented. Finally, the treatment of osteoporotic fractures of the thoracolumbar spine is reviewed, including vertebroplasty and kyphoplasty, their risks and controversies, and senile burst fractures, as well. Conclusions Thoracolumbar spine fractures remain a significant source of potential morbidity. Advances in treatment have minimized the invasiveness of our surgery and in certain stable situations, eliminated it all together.

Evaluation of the loads on lumbar intervertebral discs (IVD) is critically important since it is closely related to spine biomechanics, pathology and prosthesis design. Non-invasive estimation of the loads in the discs remains a challenge. In this study, we proposed a new technique to estimate in vivo loads in the IVD using a subject-specific finite element (FE) model of the disc and the kinematics of the disc endplates as input boundary conditions. The technique was validated by comparing the forces and moments in the discs calculated from the FE analyses to the in vitro experiment measurements of three corresponding lumbar discs. The results showed that the forces and moments could be estimated within an average error of 20%. Therefore, this technique can be a promising tool for non-invasive estimation of the loads in the discs and may be extended to be used on living subjects.

Lumbar degenerative spondylolisthesis (DS), typically characterized by the forward slippage of the superior vertebra of a lumbar motion segment, is a common spinal pathological condition in elderly individuals. Significant deformation and volume changes of the spinal canal can occur because of the vertebral slippage, but few data have been reported on these anatomic variations in DS patients. Whether to restore normal anatomy, such as reduction of the slippage and restoration of disc height, is still not clear in surgery.This study was designed to determine the volume change of the spinal canal and detect specific anatomic factors affecting the spinal canal volume in DS patients.A case-control study.Nine asymptomatic volunteers (mean age 54.4) and 9 patients with L4/L5 DS (mean age 73.4) were recruited. All patients had intermittent claudication and different extent low back pain, and two patients also had leg pain. L4/L5 vertebral motion segment unit of each subject was reconstructed using three-dimensional computed tomography or magnetic resonance images in a solid modeling software. In vivo lumbar vertebral motion during functional postures (supine, standing upright, flexion, and extension) was determined using a dual fluoroscopic imaging technique. The volume of the spinal canal was measured at each functional posture. Various anatomic parameters (disc height, cross-sectional area of the canal, left-right diameter of the canal, anterior-posterior diameter of the canal, slippage, posture, intervertebral disc angle [DA], etc.) that may potentially affect the canal volume were also measured, and their correlations with the volume change of spinal canal were analyzed. This study was funded by a 2-year, $275,000 grant from the National Institutes of Health.On average, spinal canal volume was larger at supine and flexion postures than at stand and extension postures in both the DS and the asymptomatic groups. Spinal canal volume of the DS patients were significantly lower than that of the asymptomatic subjects under all the four postures (p.05). Correlation analysis showed that spinal canal volume was strongly affected by the posterior disc height (Pearson correlation coefficient γb=0.822) and the slippage percentage (γb=-0.593) and moderately affected by the anterior disc height (γb=0.300) and the DA (γb=-0.237).The volume of spinal canal is affected by multiple factors. Increased spinal canal volume at supine and flexion positions may explain the clinical observations of relief of symptoms at these postures in DS patients. The data also suggest that reduction of slipped vertebral body, decrease of DA, intervertebral distraction, and decompression could all be effective to increase the canal volume of DS patients thus to relieve clinical symptoms.

STUDY DESIGN Multicenter, retrospective series. OBJECTIVE To analyze the incidence, mode, and location of acute proximal junctional failures (APJFs) after surgical treatment of adult spinal deformity. SUMMARY OF BACKGROUND DATA Early proximal junctional failures above adult deformity constructs are a serious clinical problem; however, the incidence and nature of early APJFs remain unclear. METHODS A total of 1218 consecutive adult spinal deformity surgeries across 10 deformity centers were retrospectively reviewed to evaluate the incidence and nature of APJF, defined as any of the following within 28 weeks of index procedure: minimum 15° post-operative increase in proximal junctional kyphosis, vertebral fracture of upper instrumented vertebrae (UIV) or UIV + 1, failure of UIV fixation, or need for proximal extension of fusion within 6 months of surgery. RESULTS Sixty-eight APJF cases were identified out of 1218 consecutive surgeries (5.6%). Patients had a mean age of 63 years (range, 26-82 yr), mean fusion levels of 9.8 (range, 4-18), and mean time to APJF of 11.4 weeks (range, 1.5-28 wk). Fracture was the most common failure mode (47%), followed by soft-tissue failure (44%). Failures most often occurred in the thoracolumbar region (TL-APJF) compared with the upper thoracic region (UT-APJF), with 66% of patients experiencing TL-APJF compared with 34% experiencing UT-APJF. Fracture was significantly more common for TL-APJF relative to UT-APJF (P = 0.00), whereas soft-tissue failure was more common for UT-APJF (P < 0.02). Patients experiencing TL-APJF were also older (P = 0.00), had fewer fusion levels (P = 0.00), and had worse postoperative sagittal vertical axis (P < 0.01). CONCLUSION APJFs were identified in 5.6% of patients undergoing surgical treatment of adult spinal deformity, with failures occurring primarily in the TL region of the spine. There is evidence that the mode of failure differs depending on the location of UIV, with TL failures more likely due to fracture and UT failures more likely due to soft-tissue failures.

Little is known about the coupled motions of the spine during functional dynamic motion of the body. This study investigated the in vivo characteristic motion patterns of the human lumbar spine during a dynamic axial rotation of the body. Specifically, the contribution of each motion segment to the lumbar axial rotation and the coupled bending of the vertebrae during the dynamic axial rotation of the body were analyzed.Eight asymptomatic subjects (M/F, 7/1; age, 40-60 years) were recruited. The lumbar segment of each subject was MRI scanned for construction of 3D models of the vertebrae from L2 to S1. The lumbar spine was then imaged using a dual fluoroscopic system while the subject performed a dynamic axial rotation from maximal left to maximal right in a standing position. The 3D vertebral models and the fluoroscopic images were used to reproduce the in vivo vertebral motion. In this study, we analyzed the primary left-right axial rotation, the coupled left-right bending of each vertebral segment from L2 to S1 levels.The primary axial rotations of all segments (L2-S1) followed the direction of the body axial rotation. Contributions of each to the overall segment axial rotation were 6.7° ± 3.0° (27.9 %) for the L2-L3, 4.4° ± 1.2° (18.5 %) for the L3-L4, 6.4° ± 2.2° (26.7 %) for the L4-L5, and 6.4° ± 2.6° (27.0 %) for the L5-S1 vertebral motion segments. The upper segments of L2-L3 and L3-L4 demonstrated a coupled contralateral bending towards the opposite direction of the axial rotation, while the lower segments of L4-L5 and L5-S1 demonstrated a coupled ipsilateral bending motion towards the same direction of the axial rotation. Strong correlation between the primary axial rotation and the coupled bending was found at each vertebral level. We did not observe patterns of coupled flexion/extension rotation with the primary axial rotation.This study demonstrated that a dynamic lumbar axial rotation coupling with lateral bendings is segment-dependent and can create a coordinated dynamic coupling to maintain the global dynamic balance of the body. The results could improve our understanding of the normal physiologic lumbar axial rotation and to establish guidelines for diagnosing pathological lumbar motion.

STUDY DESIGN Survey based on complication scenarios. OBJECTIVE To assess and compare perceived potential impacts of various perioperative adverse events by both surgeons and patients. SUMMARY OF BACKGROUND DATA Incidence of adverse events after adult spinal deformity surgery remains substantial. Patient-centered outcomes tools measuring the impact of these events have not been developed. An important first step is to assess the perceptions of surgeons and patients regarding the impact of these events on surgical outcome and quality of life. METHODS Descriptions of 22 potential adverse events of surgery (heart attack, stroke, spinal cord injury, nerve root injury, cauda equina injury, blindness, dural tear, blood transfusion, deep vein thrombosis, pulmonary embolism, superficial infection, deep infection, lung failure, urinary tract infection, nonunion, adjacent segment disease, persistent deformity, implant failure, death, renal failure, gastrointestinal complications, and sexual dysfunction) were presented to 14 spinal surgeons and 16 adult patients with spinal deformity. Impact scores were assigned to each complication on the basis of perceptions of overall severity, satisfaction with surgery, and effect on quality of life. Impact scores were compared between surgeons and patients with a Wilcoxon/Kruskal-Wallis test. RESULTS Mean impact scores varied from 0.9 (blood transfusion) to 10.0 (death) among surgeons and 2.3 (urinary tract infection) to 9.2 (stroke) among patients. Patients' scores were consistently higher (P < 0.05) than surgeons in all 3 categories for 6 potential adverse events: stroke, lung failure, heart attack, pulmonary embolism, dural tear, and blood transfusion. Three additional complications (renal failure, non-union, and deep vein thrombosis) were rated higher in 1 or 2 categories by patients. CONCLUSION There was substantial variation in how both surgeons and patients perceived impacts of various adverse events after spine surgery. Patients generally perceived the impact of adverse events to be greater than surgeons. Patient-centered descriptions of adverse events would provide a more complete description of surgical outcomes.

OBJECTIVE A previous multilevel fusion mass encountered during revision spinal deformity surgery may obscure anatomical landmarks, making instrumentation unworkable or incurring substantial blood loss and operative time. This study introduced a surgical technique of multiple-hook fixation for fixating previous multilevel fusion masses in revision spinal deformity surgeries and then evaluated its outcomes. METHODS Patients with a previous multilevel fusion mass who underwent revision corrective surgery down to the lumbosacral junction were retrospectively studied. Multiple hooks were used to fixate the fusion mass and linked to distal pedicle screws in the lumbosacral-pelvic complex. Radiological and clinical outcomes were evaluated. RESULTS The charts of 8 consecutive patients with spinal deformity were retrospectively reviewed (7 women, 1 man; mean age 56 years). The primary diagnoses included flat-back deformity (6 cases), thoracolumbar kyphoscoliosis (1 case), and lumbar spondylosis secondary to a previous scoliosis fusion (1 case). The mean follow-up duration was 30.1 months. Operations were performed at T3/4–ilium (4 cases), T7–ilium (1 case), T6–S1 (1 case), T12–S1 (1 case), and T9–L5 (1 case). Of 8 patients, 7 had sagittal imbalance preoperatively, and their mean C-7 plumb line improved from 10.8 ± 2.9 cm preoperatively to 5.3 ± 3.6 cm at final follow-up (p = 0.003). The mean lumbar lordosis of these patients at final follow-up was significantly greater than that preoperatively (35.2° ± 12.6° vs 16.8° ± 11.8°, respectively; p = 0.005). Two perioperative complications included osteotomy-related leg weakness in 1 patient and a stitch abscess in another. CONCLUSIONS The multiple-hook technique provides a viable alternative option for fixating a previous multilevel fusion mass in revision spinal deformity surgery.

In vivo patient biomechanical study.To investigate the dimensions of lumbar intervertebral foramen (LIVF) of patients with degenerative disc disease (DDD) during a flexion-extension motion of the body.LIVF narrowing may result in nerve root compression. The area changes of degenerated and adjacent nondegenerated LIVFs in DDD patients under physiologic loading conditions are unknown.Nine symptomatic low back pain patients with radiological evidence of L4-S1 DDD were recruited. Each subject was magnetic resonance imaging scanned for construction of three-dimensional lumbar vertebral models, and fluoroscopically imaged when the body extended from 45 flexion to full extension for reconstruction of LIVF dimensions. The data of the adjacent segment L3/4 and diseased segments L4/5 and L5/S1 were compared with a normal control group at 45 flexion, upright, and full extension of the body.The mean LIVF areas of DDD segments were significantly smaller than those of the normal subjects in all positions (P 0.05). In upright position, the LIVF areas of the DDD patients were 32.8% and 33.6% smaller than the normal subjects for L4/5 and L5/S1, respectively. For the adjacent L3/4, the LIVF area of the DDD patients was 32.3% smaller than that of the normal controls (P 0.05). The total change of L3/4 LIVF area in DDD patients from flexion to extension was significantly smaller than that of the normal subjects, but the changes in L4/5 and L5/S1 LIVF areas were similar between the two groups (P 0.05).Similar reductions of the LIVF dimensions were observed at the adjacent and the involved levels of the DDD patients, implying that biomechanical changes might have already occurred at the adjacent segment despite the lack of radiographic evidence of degeneration. Subsequent research should focus on the effects of surgical fusion on the biomechanical features of the adjacent segment.N/A.

When a patient presents with spine problems, the spine surgeon would do well to avoid use of, reliance on, and acceptance of radiographs as the sole or primary source of information. Measurement of pelvic incidence and lumbar lordosis, although crucial, does not take into account the effort the patient must make to move, the level of involvement of other parts of the body, and the history of previous procedures and outcomes. Radiographs may show pathology that is not consistent with the appearance of the patient. How should we assess this situation?

Although some studies have reported on the kinematics of the lumbar segments with degenerative spondylolisthesis (DS), few data have been reported on the in vivo 6 degree-of-freedom kinematics of different anatomical structures of the diseased levels under physiological loading conditions. This research is to study the in vivo motion characteristics of the lumbar vertebral segments with L4 DS during weight-bearing activities.Nine asymptomatic volunteers (mean age 54.4) and 9 patients with L4 DS (mean age 73.4) were included. Vertebral kinematics was obtained using a combined MRI/CT and dual fluoroscopic imaging technique. During functional postures (supine, standing upright, flexion, and extension), disc heights, vertebral motion patterns and instability were compared between the two groups.Although anterior disc heights were smaller in the DS group than in the normal group, the differences were only significant at standing upright. Posterior disc heights were significantly smaller in DS group than in the normal group under all postures. Different vertebral motion patterns were observed in the DS group, especially in the left-right and cranial-caudal directions during flexion and extension of the body. However, the range of motions of the both groups were much less than the reported criteria of lumbar spinal instability.The study showed that lumbar vertebra with DS has disordered motion patterns. DS did not necessary result in vertebral instability. A restabilization process may have occurred and surgical treatment should be planned accordingly.

Scheuermann kyphosis is a structural hyperkyphosis defined radiographically as anterior wedging of ≥5° of at least three consecutive vertebral bodies. Typically, the disease develops during adolescence but may not present until adulthood. The etiology remains unknown. Indications for management include progressive deformity, pain, cosmesis, neurologic deficit, and cardiopulmonary compromise. Surgical intervention is indicated in patients with persistent pain and unacceptable deformity caused by significant kyphosis. Surgery can be performed through posterior-only, anterior-only, or combined anterior-posterior approaches. Correction should include the entire length of the kyphosis and should not exceed 50% of the original deformity. The most common postoperative complications are wound infection and loss of correction.

STUDY DESIGN Consecutive, multicenter retrospective review. OBJECTIVE To evaluate if change in thoracic kyphosis (TK) has a positive or negative impact on spinopelvic alignment after lumbar pedicle subtraction osteotomy (PSO) with short fusions. SUMMARY OF BACKGROUND DATA In the setting of sagittal malalignment, the effect of large vertebral resections can now be anticipated in long fusions, but their impact on unfused segments (reciprocal changes [RC]) remains poorly understood. METHODS A total of 34 adult patients (mean age = 54 years; SD = 12) who underwent lumbar PSO with upper instrumented vertebra below T10 were included. Radiographic analysis included pre- and postassessment of TK, lumbar lordosis (LL), sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPI), pelvic tilt (PT), and pelvic incidence (PI). Final SVA and PT were analyzed to determine successful realignment. RC in the thoracic spine was designated favorable or unfavorable on the basis of impact on final SVA and PT. RESULTS Mean PSO resection was 26°. LL increased from 20° to 49° (P < 0.001). SVA improved from 14 to 4 cm (P < 0.001), and PT improved from 33° to 25° (P < 0.001). Mean increase in TK was 13° (P = 0.002) but was unchanged in 11 patients. Five patients had a favorable RC, and 18 patients had an unfavorable RC. Unfavorable RC was attributed to junctional failure in 6 of 18 patients. Significant differences in the unfavorable RC group included age and greater preoperative PT, PI, SVA, and T1SPI. CONCLUSION Significant postoperative alignment changes can occur through unfused thoracic spinal segments after lumbar PSO. Unfavorable RC may limit optimal correction and lead to clinical failures. Risk factors for unfavorable thoracic RC include older patients, larger preoperative PI and PT, and worse preoperative T1SPI and are not simply due to junctional failure. Care should be taken with selective lumbar fusion and PSO in older patients and in those with severe preoperative spinopelvic parameters.

Systematic review.To determine if the presence of isthmic spondylolisthesis modifies the effect of treatment (fusion vs. multidimensional supervised rehabilitation) in patients with chronic low back pain (CLBP).Results of spinal surgery for CLBP are variable. It is unclear whether patients with CLBP and isthmic spondylolisthesis have more success with surgery versus a multidimensional supervised rehabilitation program when compared with those with CLBP but without spondylolisthesis.A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for articles published through January 2011. Randomized controlled trials (RCTs) were included that compared spine fusion versus multidimensional supervised rehabilitation in patients with and without isthmic spondylolisthesis. Standardized mean differences (SMDs) and risk differences were calculated for common outcomes, and then compared to determine potential heterogeneity of treatment effect. The final strength of the body of literature was expressed as "high," "moderate," or "low" confidence that the evidence reflects the true effect.No studies were found that directly compared the two subgroups. Three RCTs compared fusion with supervised nonoperative care in patients with CLBP without isthmic spondylolisthesis; one RCT evaluated these treatments in patients with isthmic spondylolisthesis. There were study differences in patient characteristics, type of fusion, the nature of the rehabilitation, outcomes assessed, and length of follow-up. The SMDs for pain in favor of fusion were modest at 2 years for those without isthmic spondylolisthesis, but large in favor of fusion for those with isthmic spondylolisthesis compared with rehabilitation. Similarly, the SMDs for function in patients without isthmic spondylolisthesis compared with rehabilitation was small at 2 years, but appreciably higher in favor of fusion in patients with isthmic spondylolisthesis.The overall strength of evidence evaluating whether the presence of isthmic spondylolisthesis modifies the effect of fusion compared with rehabilitation patients with CLBP is "low." Fusion should be considered for patients with low back pain and isthmic spondylolisthesis who have failed nonoperative treatment.We recommend considering fusion for patients with isthmic spondylolisthesis and lower back pain who have failed nonoperative treatment.Weak.

To evaluate the biomechanical effect of the X-Stop device on the intervertebral foramen (IVF) and segmental spinal canal length (SSCL), as well as the intervertebral disc space at the implanted and the adjacent segments in patients with lumbar spinal stenosis (LSS).Eight elderly patients with LSS, scheduled for X-stop implantation, were CT or MRI scanned to construct 3D vertebral models (L2-S1). Before and after the surgery, each patient was also imaged using a dual-fluoroscopic image system during weight-bearing standing and maximum extension-flexion. The positions of the vertebrae were then determined using an established 2D-3D model matching method.The data revealed that the postoperative IVF area was significantly increased by 32.9% (or 32 mm2) (p0.05) and the IVF width was increased by 24.4% (or 1.1 mm, p=0.06) during extension, but with minimal change in standing and flexion. The IVF heights were significantly (p0.05) increased at standing by 1.2 mm and extension by 1.8 mm, but not at flexion. The SSCL were significantly (p0.05) increased at extension by 1.2 mm, but not at standing and flexion. Anterior disc space of the implanted level was significantly decreased from 8.0 to 6.6 mm during standing.The X-Stop implantation efficiently enlarged the IVF area in the elderly patients with LSS at the operated level with little biomechanical effect immediately on the superior and inferior adjacent levels. However, it reduced the anterior disc space at the implanted level.

Background: The ideal surgical treatment for adult low-grade isthmic spondylolisthesis (ALIS) remains unknown. Isolated anterior and posterior procedures are popular but have resulted in equivocal outcomes, whereas combined anterior and posterior procedures are associated with higher complication rates despite improved outcome. Objective: To evaluate the clinical and radiographic outcomes following the treatment of ALIS using a 1-stage posterior approach with posterior decompression and posterolateral arthrodesis combined with an interbody fibular allograft strut. Methods: Fifteen patients underwent fusion by a single surgeon using our modified technique. Seven patients were female and 8 were male, with a mean age of 48 years. All patients were classified as Meyerding grade II slips and underwent a posterior approach only, a decompressive laminectomy, and a circumferential fusion with the use of a transsacral fibular allograft and a posterolateral instrumented fusion. Postoperative clinical and radiographic evaluations were performed at 3, 6, and 12 months, and then on an annual basis. Results: The average follow-up interval was 61 months. Three complications were seen: a single dural tear, an L5 radiculopathy secondary to a malpositioned pedicle screw, and one patient with urinary retention. The spines of all patients were determined to be fused by the 6-month postoperative visit. All patients returned to their normal activities of daily living. Significant improvements in the visual analog score were seen at all follow-up intervals. Conclusion: Transsacral interbody fibular allograft can be used successfully to supplement a posterolateral instrumented fusion in selected patients with low-grade ALIS.

Management of odontoid fractures has been recognized as a challenge, since these injuries were first described in the early 20th century.1 Despite significant advances in diagnostic and treatment methods, such fractures remain problematic, particularly in the geriatric population.1–8 Odontoid fractures are the most common cervical spine fracture in the elderly.1,8 Because of their age associated comorbidities and the ubiquitous presence of degenerative changes in the aging cervical spine,6 such individuals are at a higher risk for complications and poorer outcomes than younger patients sustaining similar injuries.1–4,6,7,9–11 Furthermore, as the number of elderly patients continues to rise in the United States, the prevalence of such fractures can be expected to increase in the future. Several prior studies have documented increased morbidity and mortality among geriatric patients sustaining odontoid fractures.1–7,9,10,12,13 The nonunion rate in this population has been reported to be as high as 85% (range, 20%–85%),3–7,9,10,12–14 whereas the mortality rate has approached 60% (range, 10%–57.1%).2–7,9,10,12,13 Moreover, the choice of management (operative vs. nonoperative, halo-vest immobilization vs. cervical orthosis) has been postulated to influence mortality. The halo vest, in particular, has been associated with an increased risk of complications and death in elderly patients.1,3,4,7,9,12,15 One study reported high complication rates of pneumonia (34%), cardiac arrest (26%), and mortality (42%) in elderly patients treated with a halo vest.7 Most information on mortality in patients with odontoid fracture is derived from reviews of small cohorts comprising less than 50 patients.3,4,5,7,9,11,13 Furthermore, only one study specifically examined treatment-based outcomes,7 while none have analyzed mortality in relation to age, or medical comorbidities. Given the paucity of data, this investigation sought to define the influence of age, treatment, and comorbidities on mortality in a cohort (n = 156) of elderly patients sustaining Anderson and D’Alonzo16 Type II fractures of the odontoid in the cervical spine. The hypothesis was that patients treated surgically would have lower mortality than those treated nonoperatively with either a halo vest or cervical orthosis. It was also anticipated that patients with fewer medical comorbidities would have lower mortality regardless of treatment method.

Low back pain (LBP) secondary to lumbar degenerative disc disease (DDD) is one of the most common causes of disability in working population.1,2 It has been reported that in patients with DDD, the intervertebral discs (IVD) adjacent to the diseased levels have a greater tendency to degenerate,3–5 especially after surgical fusion treatment of the diseased segments.6–9 Numerous studies have suggested that altered biomechanics, such as abnormal loading and/or motion patterns,10–12 are the causative factors of adjacent segment degeneration (ASD). However, it remains unclear whether these changes are due to the natural development triggered by the DDD13–16 or to the consequence of spinal surgeries.6,17,18 Therefore, a quantitative knowledge of the disc deformation at the adjacent segments under physiologic weight-bearing conditions is instrumental to delineate the biomechanical factors associated with ASD. Many studies have examined the biomechanics of the adjacent segments after lumbar fusion or disc arthroplasty in vivo and in vitro. For example, segmental mobility19–23 and change in disc height9,18,19,24,25 have been measured using sagittal plane radiographs in patients after surgical treatments of the diseased discs. In vitro cadaveric tests and computational simulations have been used to investigate the effect of surgical treatments on loadings of the facet joints,26–30 intradiscal pressure,31–34 disc bulging,35 and stress-strain distribution.36–38 Few studies have investigated the effect of DDD on the biomechanics of the adjacent segments before surgical treatments. In finite element studies,35,39 disc degeneration was simulated by changing the disc height and its material properties, and adjacent segmental motions and disc stress-strain distributions were calculated under combined axial compressive forces and moments.35,39 However, the disc deformation at the segments adjacent to the DDD levels in living patients remains unclear. We have recently developed a combined magnetic resonance imaging (MRI) and dual fluoroscopic imaging system (DFIS) technique to quantify the disc geometric deformation in vivo.40 The purpose of this study was to quantitatively evaluate the effect of lumbar DDD on the disc deformation at the adjacent level and the level one above the adjacent level during in vivo end ranges of lumbar spine motions, which corresponded to the extreme motions experienced during daily activities. In 10 patients with DDD with degenerated discs between L4 and S1, disc L3–L4 and L2–L3 were studied and compared with those of eight asymptomatic healthy subjects. We hypothesized that DDD can cause the healthy cephalic L3–L4 and L2–L3 segments to undergo larger deformation than normal subjects.

Several reports indicate that patients with ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) have increased mortality after cervical spine fractures. However, outcomes of the fractured hyperostotic cervical spine are incompletely described, and there are limited data regarding the covariable effects of patient age and medical comorbidities on mortality.To determine mortality associated with cervical fractures in patients with hyperostotic disease.Retrospective case-control study.Forty-three patients identified through a registry as having fractures of the cervical spine in the setting of hyperostotic disease. These patients were matched to 43 controls who did not carry the diagnosis of hyperostotic disease.Mortality at 3 months and 1, 2, and 3 years after fracture.An institutional database was used to identify all cervical fractures sustained by patients aged 65 years and older from 1991 to 2006. Demographic information, date of injury, associated injuries, treatment type, presence of AS or DISH, and comorbidities were abstracted from medical records and radiographs. Mortality was ascertained using the National Death Index. Patients with AS or DISH were matched to controls who did not carry the diagnosis of hyperostotic disease. Risks of mortality were calculated at 3 months, 1 year, 2 years, and 3 years. Kaplan-Meier methods, logistic regression analysis, the two independent sample t test, and the Fisher exact test were used to compare mortalities between the two groups. Statistical significance was determined as p values.05.Forty-three patients were identified as having fractures in the setting of hyperostotic disease of the cervical spine. Twenty-seven individuals had DISH, and 16 had AS. The average age of both the study group and controls was 80 years, with an age range of 68 to 94. There was no significantly increased risk of mortality between the overall study group and control group at 3 months (p=.20), 1 (p=.22), 2 (p=.15), or 3 years (p=.50) after injury. Compared with controls, subgroup analysis of patients with AS showed a statistically increased risk of mortality at 3 months (p.01) and at 1 and 2 years (p.01 at both time points). When compared with individuals with DISH, those with AS had an increased risk of mortality at time points up to 2 years after fracture. Patients with DISH did not have an increased mortality risk at any time point when compared with controls.The effect of fracture on mortality appears to be greatest in those with AS. Patients with DISH did not demonstrate an increased risk of mortality compared with age- and sex-matched controls. Future studies of patients with hyperostotic disease should analyze patients with DISH and AS separately instead of as a single homogenous group.Level IV.

Study design Retrospective radiographic study of the technique for C1 lateral mass screw (C1LMS) and C2 pedicle screw (C2PS) fixation. Objective To evaluate (1) the accuracy of the C1LMS and C2PS placement; (2) the fusion rate between C1 and C2; (3) the risk for vertebral artery (VA) injury. Summary of background data C1LMS and C2PS fixation is widely used when treating atlantoaxial instability. Several authors have reported their experience focusing on the technical outcomes, with many reporting fusion rates near 100%. However, most of them are relatively small series, and many have applied only plain postoperative radiographs instead of computed tomography (CT). Thus, we feel that the accuracy of C1LMS and C2PS placement has not been fully analyzed, as well as the anatomic relationship between the VA and the screws. Methods Between December 2000 and September 2008, the fusion status and accuracy of the screws were evaluated on the postoperative reconstructive CT of 319 patients with atlantoaxial instability. Cases with malpositioned screws underwent CT angiography or magnetic resonance angiography after surgery, to evaluate potential VA injury. Results C1LMS of 95.5% and C2PS of 92.8% were found to be in a "good" position. After 2007, six cases had malpositioned screws, which were all in the "out" or "down" area of the C2 pedicle. Five cases underwent CT angiography and 1 had magnetic resonance angiography to evaluate potential VA injury. No occlusion, associated aneurysm or fistula of the VA was found. All cases (100%) achieved solid fusion between C1 and C2. Conclusion C1LMS of 95.5% and C2PS of 92.8% were confirmed to be in good position. None of the screws including the malpositioned caused VA injury, clinically or radiographically. The technique for C1LMS and C2PS fixation appears to be safe and effective.