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The rate of implant removal and the factors influencing its indication in patients with distal radius fracture (DRF) in Japan are unclear.We retrospectively evaluated the incidence rate of implant removal in a large cohort of DRF patients obtained from the Diagnosis Procedure Combination database in Japan between April 2014 and March 2019. Patient- and hospital-related factors possibly affecting removal rate, including age, sex, annual number of open reduction and internal fixation (ORIF) for DRF procedures per hospital, number of hospital beds, advanced or general care hospital, and hospital location were analyzed as well. Hospital location was classified into three types based on population and population density as 1) large city, 2) local city, and 3) sparse area.Implant removal was performed in 3242 (26.3%) of 12,328 DRF patients receiving ORIF. According to multivariate analysis, the significant factors related to a decreased probability of removal were older patients, male, large annual number of ORIF for DRF procedures per hospital, large number of hospital beds, advanced care hospital, and hospital in large city.This study clarified the current implant removal rate and trends following ORIF for DRF in Japan. Both patient- and hospital-related factors significantly impacted the decision for implant removal.

An increasing number of medical centers are adopting an intraoperative computed tomography (iCT) navigation system (iCT-Navi) to provide three-dimensional navigation for pediatric scoliosis surgery. While iCT-Navi has been reported to provide higher pedicle screw (PS) insertion accuracy, it may also result in higher radiation exposure to the patient. What innovations and studies have been introduced to reduce radiation exposure and further improve PS insertion?Evaluate the level of evidence and quality of papers while categorizing the tips and pitfalls regarding pediatric scoliosis surgery using iCT-Navi. Compare iCT-Navi with other methods, including preoperative CT navigation.Systematic review.Articles on pediatric scoliosis surgery with iCT-Navi published through to June 2022.PS perforation rate and patient intraoperative radiation dose.Following PRISMA guidelines, the Cochrane Library, Google Scholar, and PubMed databases were searched for articles satisfying the criteria of iCT-Navi use and pediatric scoliosis surgery. The level of evidence and quality of the articles meeting the criteria were evaluated according to the guidelines of the North American Spine Society and American Academy of Orthopedic Surgeons, respectively. The articles were also categorized by theme and summarized in terms of PS insertion accuracy and intraoperative radiation dose. The origins and characteristics of five major classification methods of PS perforation grade were summarized as well.The literature search identified 811 studies, of which 20 papers were included in this review. Overall, 513 pediatric scoliosis patients (381 idiopathic, 44 neuromuscular, 39 neurofibromatosis type 1, 28 congenital, 14 syndromic, seven other) were evaluated for PS perforations among 6,209 iCT-Navi insertions. We found that 232 (3.7%) screws were judged as major perforations (G2 or G3), 55 (0.9%) screws were judged as dangerous deviations (G3), and seven (0.1%) screws were removed. There were no reports of neurovascular injury caused by PSs. The risk factors for PS perforation included more than six vertebrae distance from the reference frame, more than nine consecutive insertions, upper thoracic level, thinner pedicle, upper instrumented vertebra proximity, short stature, and female. The accuracy of PS insertion did not remarkably decrease when the radiation dose was reduced to 1/5 or 1/10 by altering the iCT-Navi protocol.iCT-Navi has the potential to reduce PS perforation rates compared with other methods. The use of low-dose radiation protocols may not significantly affect PS perforation rates. Although several risk factors for PS perforation and measures to reduce radiation dose have been reported, the current evidence is limited by a lack of consistency in classifying PS perforation and evaluating patient radiation dose among studies. The standardization of several outcome definitions is recommended in this rapidly developing field.

To evaluate the surgical results of patients with cervical spondylotic myelopathy (CSM) with inconsistency between deep tendon reflex findings and cervical magnetic resonance imaging (MRI) findings and to analyze the differences between patients with good and poor surgical outcomes.We evaluated 50 subjects with CSM (30 males, 20 females; mean age: 70.4 years) who underwent posterior surgery and were followed for at least 1 year postoperatively. Matched CSM was defined as a consistent preoperative neurological pattern determined by deep tendon reflex and cervical MRI T2-weighted high-signal intramedullary area or stenosis in the most cranial compression levels. A lack of consistency was classified as unmatched CSM. Recovery rate (RR) according to Japanese Orthopaedic Association (JOA) scoring preoperatively and at 1 year postoperatively were compared between the groups.The matched and unmatched CSM group included 27 subjects (13 males, 14 females; mean age: 68.2 years) and 23 subjects (17 males, 6 females; mean age: 72.8 years), respectively. RR was significantly higher in the matched CSM group (56.1 ± 3.7 % vs 36.8 ± 2.7 %; p = 0.002). Unmatched CSM was significantly associated with a lower RR independently of sex, patient age, surgical procedure, preoperative JOA score, diagnosis levels, and complication of diabetes.Postoperative JOA score RR was significantly diminished among unmatched CSM patients comprising of 46% of cases. Some patients with unmatched CSM had multiple levels of spinal canal stenosis, foraminal stenosis, and peripheral neuropathy, suggesting that surgical results were poorer than those of matched CSM.

This trial evaluated the superiority of intraoperative wound irrigation (IOWI) with aqueous povidone-iodine (PVP-I) compared to that with saline for reducing the incidence of surgical site infection (SSI).IOWI with aqueous PVP-I is recommended for the prevention of SSI by the World Health Organization and Centers for Disease Control and Prevention, although the evidence level is low.This single-institute in Japan, prospective, randomized, blinded-endpoint trial was conducted to assess the superiority of IOWI with aqueous PVP-I in comparison to IOWI with saline for reducing the incidence of SSI in clean-contaminated wounds after gastroenterological surgery. Patients ≥20 years old were assessed for eligibility, and eligible participants were randomized at a 1:1 ratio using a computer-generated block randomization. In the study group, IOWI was performed for one minute with 40 mL of aqueous 10% PVP-I before skin closure. In the control group, the procedure was performed with 100 mL of saline. Participants, assessors, and analysts were masked to the treatment allocation. The primary outcome was the incidence of incisional SSI in the intention-to-treat set.Between June 2019 and March 2022, 941 patients were randomized to the study group (473 patients) or the control group (468 patients). The incidence of incisional SSI was 7.6% in the study group and 5.1% in the control group (risk difference 0.025, 95% CI -0.006 to 0.056; risk ratio 1.484, 95% CI 0.9 to 2.448; P=0.154).The current recommendation of IOWI with aqueous PVP-I should be reconsidered.

Posterior spinal fusion with pedicle screws is commonly used for the treatment of adolescent idiopathic scoliosis (AIS). To reduce radiation exposure, methods other than computed tomography (CT) are desirable for preoperative determination of pedicle diameter.Investigate the differences between magnetic resonance imaging (MRI) and CT measurements of pedicle diameter.Cross-sectional research.Twenty-one AIS Lenke type 1 patients (19 female and 2 males, mean age at surgery: 15.4 years) who underwent posterior spinal fusion between April 2009 and October 2019.Gap between CT and MRI pedicle diameters.The inner and outer diameters of the right and left pedicles from T1 to L3 were measured separately by two spine surgeons for statistical comparisons.The respective minimum and maximum CT-MRI values were -3.7 mm and 4.7 mm for inner diameter and -4.6 mm and 5.3 mm for outer diameter. Regarding inter-examiner error, the probability of a 2 mm difference in measurement was less than 5% for both modalities. The probability of a 1 mm difference was also less than 5%, and that of a 3 mm or more difference was 2.1% for the inner diameter and 2.9% for the outer diameter. Whereas low body weight was significantly associated with measurement differences, pedicle laterality was not.MRI does not have the reliability to measure pedicle size in AIS patients at present. However, with advancements in image processing technology, the accuracy of pedicle size measurement by MRI may soon improve.

This study evaluated major vascular injury risk in distal femoral osteotomy (DFO) via the subvastus approach and examined the relationship between the posterior border of the vastus medialis (VM) and the superficial femoral artery (SFA) and vein (SFV).Eighty limbs from 80 patients were evaluated using lower extremity computed tomographic venography. The positional relationship between the VM, SFA, and SFV was evaluated by measuring the angle between each structure and the horizontal reference point (VMA: VM angle, FAA (femoral arterial angle), FVA (femoral venous angle) and the distance between VM and the SFA and SFV (VMAD: VM-arterial distance, VMVD: VM-venous distance) in each axial slice (0/10/20/30/40 mm) proximal to the level of the superior patellar margin. The proximity of the posterior border of the VM and the SFA/SFV as a vertical distance, measured between the slice of the superior border of the patella and the slice where the posterior border of the VM contacted the SFA was evaluated. Single and multiple regression analyses were performed using the vertical distance as the objective variable.As the slice shifted proximally, the VMA significantly increased (24.9 ± 8.5, 36.3 ± 8.8, 47.4 ± 11.8, 59.9 ± 14, 70.3 ± 13.7 degrees, respectively, p 0.001 between all slices) and moved posteromedially from a medial direction. FAA (94.2 ± 7, 86.9 ± 9.2, 78.4 ± 9.7, 71.4 ± 9.8, 66.6 ± 10.5 degree, respectively, p 0.001 between all slices) and FVA (100.6 ± 4.9, 98.3 ± 5.9, 93.7 ± 7.5, 88 ± 9.2, 81.1 ± 10.5 degrees, respectively, p 0.001 between all slices) decreased and moved from a posterolateral to a posteromedial direction, while VMAD (35.4 ± 7.8, 24.1 ± 7.3, 14.3 ± 6, 8.4 ± 7, 6.2 ± 6.3 mm, respectively, p 0.001 between all slices) and VMVD significantly decreased (42.7 ± 7.3, 32 ± 7.4, 22.4 ± 6.8, 14.5 ± 10.6, 8.7 ± 7.1 mm, respectively, p 0.001 between all slices). The average vertical distance was 36 ± 9.3 mm (range 18.6-61.5 mm). The body height and the patellar length significantly affected the vertical distance.The posterior border of the VM shifted posteromedially from distal to proximal and contacted the SFA at an average of 36 mm from the suprapatellar border. Surgeons should be aware of the risk of major vascular injury during exposure and osteotomy.Case series, Level IV.

Introduction: Assessments of early postoperative bony union after posterior lumbar interbody fusion via computed tomography (CT) have revealed cases in which interbody fixation by bony union resulted in nonfusion due to bone absorption. The apparent bone union state reverted to a nonunion state several months later, exhibiting a so-called “fake union” phenomenon. Additionally, few reports have evaluated the effect of teriparatide on bony union. The present study aimed to evaluate the frequency of change in assessment from fusion to nonfusion in the postoperative follow-up of lumbar interbody fusion, compare the late postoperative bony union rates in groups with or without early postoperative fusion, and examine the effect of postoperative teriparatide in those groups. Methods: Sixty-nine subjects enrolled from multiple hospitals were prospectively evaluated following single-level lumbar interbody fusion. The patients were randomly allocated into treatment with or without weekly postoperative teriparatide. The subjects were then classified as having bony union or nonfusion at 2 months postoperatively, and fusion rates at 6 months were compared. For the evaluation of bony union, blinded radiological examinations were performed via CT. Additional comparisons were made according to teriparatide use. Results: The rate of nonunion at 6 months postoperatively in patients with fusion at 2 months postoperatively was 27.8%. Among subjects with bony union at 2 months postoperatively, the fusion rate at 6 months in those who received teriparatide was 93.3% (p=0.027) versus 57.1% in those who did not. Conclusions: The rate of nonunion at 6 months postoperatively in patients exhibiting union at 2 months after surgery was 27.8%. Postoperative weekly teriparatide treatment significantly reduced the rate of fake union.

To assess the points of consideration when performing surgical procedures for proximal femoral bone metastasis.Fourty patients who underwent surgery for proximal femoral bone metastasis from 2009 to 2019 were included. Prognostic assessments were performed based on the Katagiri scoring system. The low-risk group underwent endoprosthetic replacement (EPR) following resection, while the high-risk group underwent internal fixation (IF). For the intermediate-risk group, one of the surgical procedures was chosen depending on general and local condition. Survival period, walking ability, and treatment failure were evaluated.Sixteen and 24 patients underwent EPR and IF, respectively. Although walking reacquisition rate was 94% (15 of 16 patients) for EPR and 75% (18 of 24 patients) for IF (p = 0.210), the median time to walking was shorter in IF compared to EPR (EPR, 29 days, interquartile range [IQR] 23-40; IF, 14 days, IQR 9-24; p = 0.014). Neither EPR nor IF resulted in treatment failure for those with survival periods of1 year. The treatment failure rate for those with survival periods of ≥1 year was significantly different between EPR (9%, 1 of 11 patients) and IF (50%, 5 of 10 patients) (p = 0.038). All five patients of treatment failure for IF were renal cancer with no bone formation in the intermediate-risk group. Of the 13 patients who underwent IF for the intermediate-risk group, treatment failure did not occur in 5 patients with bone formation.Although EPR is a more reliable treatment than IF, patients with life expectancy of1 year are sufficiently manageable with IF. For the intermediate-risk group, EPR should be selected for cases without expected bone formation, and IF can be considered for cases with expected bone formation due to the risk of treatment failure for IF at ≥ 1 year after surgery.

Introduction: In this study, we present “microscopic mini-open foraminotomy (MicroMOF)” as a new, less invasive method for posterior cervical foraminotomy. Technical Note: Using surgical microscope guidance, the spinous process is hemi-split, and the posterior muscle is detached from the laminar subperiosteal surface. Bony resection is then performed obliquely from medial posterior to lateral anterior under lateral-tilted surgical field exposure. MicroMOF has been performed successfully for cervical radiculopathy and cervical spondylotic amyotrophy, which achieved postoperative symptom improvement with few complications. Conclusions: The novel MicroMOF foraminotomy technique has been found to protect the nerve root and vertebral artery and help preserve muscle and cervical facet joint bone.

Background Postoperative intracranial complications are rare in spine surgery not including cranial procedures. We describe an uncommon case of pseudohypoxic brain swelling (PHBS) and secondary hydrocephalus after transforaminal lumbar interbody fusion (TLIF) presenting as impaired consciousness and repeated seizures. Case presentation A 65-year-old man underwent L4-5 TLIF for lumbar spondylolisthesis and began experiencing generalized seizures immediately postoperatively. Computed tomography (CT) revealed diffuse cerebral edema-like hypoxic ischemic encephalopathy. He was transported to our hospital, at which time epidural drainage was halted and anti-edema therapy was commenced. His impaired consciousness improved. However, he suffered secondary hydrocephalus due to continuous bleeding from a dural defect and spinal epidural fluid collection 3 months later. Following the completion of dural repair and insertion of a ventriculoperitoneal shunt, his neurologic symptoms and neuroimaging findings improved significantly. Conclusions PHBS can be considered in patients with unexpected neurological deterioration following lumbar spine surgery even with the absence of documented durotomy. This might be due to postoperative intracranial hypotension-associated venous congestion, and to be distinguished from the more common postoperative cerebral ischemic events-caused by arterial or venous occlusions-or anesthetics complications.

A 49-year-old woman underwent anatomic double-bundle anterior cruciate ligament reconstruction using a hamstring tendon. Due to knee osteoarthritis progression, total knee arthroplasty was performed 13 years after the surgery. The anteromedial (AM) bundle was composed partly of tendon-like tissue and partly of scar-like tissue. In the tendon-like part of the AM bundle, the collagen fibers were slightly loose and showed a low-frequency crimp structure with an ovoid cell shape. In contrast, the collagen arrangement in the scar-like part was irregular, edematous, and sparsely cell-dense, with an ovoid cell shape. The posterolateral bundles were generally composed of spindle-shaped cells, and the collagen was arranged in tight cohesion and had well-demarcated bundles with normal crimping. Within the tibial tunnel, the graft was mainly connected to the surrounding lamellar bone on the posterior sides, with sparser connections on the anterior and medial/lateral side. The findings of this long-term case provide valuable information to enable understanding of multiple-folded hamstring tendons.Level of evidence V.

BackgroundThe procoagulant state in cancer increases the thrombotic risk, and underlying cancer could affect treatment strategies and outcomes in patients with ischemic stroke. However, the histopathological characteristics of retrieved thrombi in patients with cancer have not been well studied. This study aimed to assess the histopathological difference between thrombi in patients with and without cancer.MethodsWe studied consecutive patients with acute major cerebral artery occlusion who were treated with endovascular therapy between October 2010 and December 2016 in our single-center registry. The retrieved thrombi were histopathologically investigated with hematoxylin and eosin and Masson’s trichrome staining. The organization and proportions of erythrocyte and fibrin/platelet components were studied using a lattice composed of 10×10 squares.ResultsOf the 180 patients studied, 17 (8 women, age 76.5±11.5 years) had cancer and 163 (69 women, age 74.1±11.2 years) did not. Those with cancer had a higher proportion of fibrin/platelets (56.6±27.4% vs 40.1±23.9%, p=0.008), a smaller proportion of erythrocytes (42.1±28.3% vs 57.5±25.1%, p=0.019), and higher serum D-dimer levels (5.9±8.2 vs 2.4±4.3 mg/dL, p=0.005) compared with the non-cancer cases. Receiver operating characteristic curve analysis showed the cut-off ratio of fibrin/platelet components related to cancer was 55.7% with a sensitivity of 74.8%, specificity 58.8% and area under the curve (AUC) value of 0.67 (95% CI 0.53 to 0.81), and the cut-off ratio of erythrocyte components was 44.7% with a sensitivity of 71.2%, specificity 58.9% and AUC value of 0.66 (95% CI 0.51 to 0.80).ConclusionsThromboemboli of major cerebral arteries in patients with cancer were mainly composed of fibrin/platelet-rich components.

Purpose The aim of this study was to verify the effects of a new remnant augmentation technique with anatomical double-bundle anterior cruciate ligament (ACL) reconstruction for postoperative clinical scores, anterior stability and frequency of complications compared to remnant removal and cases with remnant defects. Methods The 105 patients who underwent anatomical double-bundle ACL reconstruction were divided into three groups. If the remnant was a Crain I-III type, remnant-preserving bone tunnel creation was attempted. After the creation of the bone tunnel, good continuity was maintained in 34 patients (preserved group). Due to lost continuity, the remnant was resected in 26 patients (resected group). No identifiable remnant continuity remained (Crain IV) in 45 patients (absent group). The Lysholm knee score, Tegner activity scale, International Knee Documentation Committee (IKDC) subjective score, anterior stability measured using the KT-1000 arthrometer at 2 years postoperatively, and frequency of complications were compared among the three groups. Univariate and multiple linear regression analysis were performed to clarify the factors affecting postoperative anterior stability. Results The Lysholm knee score, Tegner activity scale, IKDC subjective score, and frequency of complications were not significantly different among the groups. The mean side-to-side difference of anterior stability was significantly better in the preserved group (0.3 ± 1.6 mm) compared to the resected group (1.6 ± 2.3 mm, p = 0.003) and absent group (1.6 mm ± 1.7, p = 0.009). The multiple linear regression analysis showed remnant preservation significantly related to postoperative anterior stability. Conclusion Although there were no differences in clinical scores, the ACL reconstruction with new preservation technique showed good anterior stability and no difference in the frequency of complications.

To investigate the effects of a new remnant-preserving double-bundle anterior cruciate ligament reconstruction (ACLR) technique, focused on avoiding remnant damage and preserving continuity of remnants, on graft maturity using magnetic resonance imaging (MRI).A total of 169 patients were divided into three groups: 41 in the preservation group, 70 in the resection group, and 58 in the absent group. In the preservation group, rather than passing the graft through the remnant tissue, the graft was reconstructed such that the anteromedial and posterolateral bundles sandwiched the remnant to avoid damage to the remnant and maintain its continuity. Based on 1-year postoperative MRI, the grafts were divided into three regions: distal, middle, and proximal. The signal/noise quotient (SNQ) of each region of interest was calculated to evaluate the signal intensity of the graft and was compared among the three groups. Additionally, to identify factors influencing graft maturity, a multiple regression analysis was performed with SNQ as the dependent variable and patient demographics, bone morphology, and surgical factors as independent variables.In a three-group comparison of mean SNQs, the distal region was 3.3 ± 3.4, 8.9 ± 8.3, and 9.0 ± 8.6 (p 0.001), the middle region was 5.3 ± 3.7, 10.9 ± 11.1, and 11.3 ± 10.2 (p 0.001), and the proximal region was 6.8 ± 4.5, 11.1 ± 8.8, and 11.7 ± 10.8 (p = 0.017), in order of the preservation, resection, and absent groups, respectively. That indicated that the remnant-preserving ACLR was more hypointense than ACLR with remnant resection or absent in all three regions. Multiple regression analysis showed that remnant preservation remained the relevant factor affecting SNQ of the graft at the distal and middle levels.The new remnant-preserving anatomic double-bundle ACLR had significantly better graft maturity, measured by SNQ on MRI, than the remnant resection and absent groups. The remnant procedure was the relevant factor affecting graft maturity.Level III.

BackgroundWe aimed to identify the large ischemic core (LIC) volume ranges in acute ischemic stroke patients that can benefit from mechanical thrombectomy (MT).MethodsConsecutive patients within 24 hours of onset of anterior circulation ischemic stroke with large vessel occlusion and ischemic core volumes of 70–300 mL were included from our single-center prospective database from March 2014 to December 2019. Subjects were divided into three groups by baseline ischemic core volume (A: 70–100 mL; B: 101–130 mL; C: >130 mL). We compared modified Rankin Scale (mRS) score 0–2 at 3 months and parenchymal hematoma between patients receiving MT and standard medical treatment (SMT), and determined clinically treatable core volume ranges for MT.ResultsOf 157 patients (86 women; median age, 81 years; median ischemic core volume, 123 mL), 49 patients underwent MT. In Group A (n=52), MT patients (n=31) showed a higher proportion of mRS 0–2 at 3 months (52% vs 5%, PConclusionsIschemic core volumes between 70 and 100 mL may benefit from MT. The treatable upper core limit is approximately 120 mL in selected patients with LIC of 70–300 mL.

OBJECTIVENonunion after posterior lumbar interbody fusion (PLIF) is associated with poor long-term outcomes in terms of health-related quality of life. Biomechanical factors in the fusion segment may influence spinal fusion rates. There are no reports on the relationship between intervertebral union and the absorption of autografts or vertebral endplates. Therefore, the purpose of this retrospective study was to evaluate the risk factors of nonunion after PLIF and identify preventive measures.METHODSThe authors analyzed 138 patients who underwent 1-level PLIF between 2016 and 2018 (75 males, 63 females; mean age 67 years; minimum follow-up period 12 months). Lumbar CT images obtained soon after the surgery and at 6 and 12 months of follow-up were examined for the mean total occupancy rate of the autograft, presence of a translucent zone between the autograft and endplate (more than 50% of vertebral diameter), cage subsidence, and screw loosening. Complete intervertebral union was defined as the presence of both upper and lower complete fusion in the center cage regions on coronal and sagittal CT slices at 12 months postoperatively. Patients were classified into either union or nonunion groups.RESULTSComplete union after PLIF was observed in 62 patients (45%), while nonunion was observed in 76 patients (55%). The mean total occupancy rate of the autograft immediately after the surgery was higher in the union group than in the nonunion group (59% vs 53%; p = 0.046). At 12 months postoperatively, the total occupancy rate of the autograft had decreased by 5.4% in the union group and by 11.9% in the nonunion group (p = 0.020). A translucent zone between the autograft and endplate immediately after the surgery was observed in 14 and 38 patients (23% and 50%) in the union and nonunion groups, respectively (p = 0.001). The nonunion group had a significantly higher proportion of cases with cage subsidence and screw loosening at 12 months postoperatively in comparison to the union group (p = 0.010 and p = 0.009, respectively).CONCLUSIONSA lower occupancy rate of the autograft and the presence of a translucent zone between the autograft and endplate immediately after the surgery were associated with nonunion at 12 months after PLIF. It may be important to achieve sufficient contact between the autograft and endplate intraoperatively for osseous union enhancement and to avoid excessive absorption of the autograft. The achievement of complete intervertebral union may decrease the incidence of cage subsidence or screw loosening.

Background Musculocontractural Ehlers-Danlos syndrome caused by pathogenic variants in CHST14 (mcEDS-CHST14) is a recently delineated connective tissue disorder characterized by multisystem congenital malformations and progressive connective tissue fragility-related manifestations. With only 2 cases of mcEDS-CHST14 containing precise information on surgical spinal correction being reported to date, there remains no consensus on treatment standards. This study describes the detailed clinical and radiologic outcomes of the third known patient with mcEDS-CHST14 who successfully underwent surgery for severe kyphoscoliosis. Case Description The patient was a 19-year-old girl with mcEDS-CHST14 who suffered from low back pain and decreased daily activities caused by progressive kyphoscoliosis. She underwent posterior spinal fusion with an all-pedicle screw construct from T4 to L4 for a preoperative main curve Cobb angle of 69 degrees and kyphotic angle of 27 degrees. Postoperative Cobb angle of the main curve and kyphotic angle were 26 and 6 degrees, respectively. Although sufficient correction was achieved without disseminated intravascular coagulation or other serious sequelae, a large amount of blood (2600 g) was lost due to tissue fragility. Her low back pain was decreased at 1 year after surgery. Conclusions On the basis of the present and 2 earlier reported cases, posterior spinal fusion may be a reasonable surgical option for severe progressive spinal deformities in patients with mcEDS-CHST14. However, careful attention is needed for possible massive blood loss from tissue fragility.

The number of elderly patients with subarachnoid hemorrhage is increasing. Elderly patients have been postulated to benefit more from endovascular coiling, compared with neurosurgical clipping. However, we based our therapeutic modality on the morphology and location of the aneurysms, rather than patients' age or their World Federation of Neurological Surgeons grade. The aim of this study was to investigate the validity of our therapeutic modality over earlier approaches by assessing their clinical outcomes.The study sample included 539 patients who underwent surgical procedures between January 2010 and May 2019. Baseline characteristics, aneurysmal morphology and location, surgical and clinical complications, and clinical outcomes were compared between elderly (defined as aged 75 years or older) and young patients.There were 124 elderly patients (23.0%) in the sample. Eighty-five elderly patients (68.5%) received neurosurgical clipping, whereas 67.0% of the young patients (P = 0.827) received neurosurgical clipping. Of the elderly patients who had a poor World Federation of Neurological Surgeons grade, 49.4% and 48.7% underwent neurosurgical clipping and endovascular coiling, respectively (P = 1.000). Elderly patients had fewer favorable outcomes (21.8%) relative to young patients (61.8%; P0.001). There were no significant differences in the rate of favorable outcomes between patients undergoing neurosurgical clipping relative to endovascular coiling (21.2% vs. 23.1%; P = 0.818).Neurosurgical clipping and endovascular coiling yield comparable clinical outcomes in elderly and young patients with subarachnoid hemorrhage. These findings indicate that using a therapeutic modality based on aneurysmal morphology and location may be an effective treatment approach.

Osteoporosis (OP) is a common disease in the elderly that causes bone fractures and increases mortality. Denosumab (DMAB) is one of several medications to treat OP. DMAB not only reduces the risk of fractures, but also improves the quality of life. However, an increase in the risk of multiple vertebral fractures has been reported after DMAB discontinuation. We described the rare case of a 71-year-old woman with severe OP who experienced same-side insufficiency fractures of the tibia and femur at 18 months after DMAB discontinuation. Careful monitoring for both vertebral and lower limb fragility fractures is advised after DMAB cessation.

Periventricular anastomosis (PA), which is a novel term for extended collateral vessels in moyamoya disease (MMD), is reportedly associated with a high risk of intracranial hemorrhage in adult patients. The present study aimed to clarify the similarities and the differences in the development of PA between three MMD groups, classified by age at the time of diagnosis and clinical phenotype. This study included 232 hemispheres of 132 patients with MMD who underwent surgical revascularization. The subjects were classified into child ischemic (CI) group, adult ischemic (AI) group, and adult hemorrhagic (AH) group. We evaluated the lenticulostriate (LSA), thalamic (THA), choroidal (ChA), anterior choroidal (AChA), and posterior choroidal (PChA) anastomosis as well as the posterior cerebral artery (PCA) involvement. The PA scores and the sums of each grade of LSA, THA, and ChA anastomosis were also calculated in all of the cases. In a multiple comparison test, the PA scores (P

Study design Multicenter, prospective randomized study. Objective Evaluate the impact of weekly teriparatide (WT) and bone contact (BC) status of grafted bone in patients recovering from multilevel lumbar interbody fusion (M-LIF). Summary of background data WT has been reported to significantly improve bone fusion following posterior or transforaminal interbody fusion in osteoporosis patients. Methods Patients older than 50 years and osteoporotic were recruited. We defined the fusion of two or more consecutive intervertebral levels as M-LIF. All patients were instrumented with pedicle, iliac, or S-2 alar iliac screws after transplanting cages and autogenous bone between vertebral bodies. After surgical indication for M-LIF, the subjects were randomly allocated to receive either subcutaneous WT from 1 week to 6 months postoperatively (WT arm, N = 50) or a bisphosphonate (BP; BP arm, N = 54). Blinded radiological evaluations were performed using computed tomography (CT). Evaluation of bone fusion was performed at the intervertebral disc located at the bottom of the fixed range. The degree of bone fusion was calculated as a score from 2 to 6 points, with 2 defined as complete fusion. Bone fusion rate was also compared at 6 months postoperatively based on BC status of the grafted bone on CT immediately after surgery. Results Mean bone fusion score at 6 months postoperatively was 3.9 points in the WT group and 4.2 points in the BP group. The bone fusion rate at 6 months postoperatively tended to be higher in the WT group (46.8% vs. 32.7% in the BP group). The 6-month postoperative fusion rate of immediately postoperative of BC+ patients was significantly higher than that of BC- patients (47.4% vs. 9.5%). Conclusion In M-LIF, there were no significant differences in bone fusion score between WT- and BP-treated patients. In contrast, BC status immediately postoperatively had a major impact on 6-month bone fusion. Level of evidence 1.

Background The clinical significance of asymptomatic microbleeds in moyamoya disease remains unclear. The purpose of this study was to clarify the relationship between bypass surgery and the incidence of asymptomatic microbleeds. Methods This retrospective study included 142 adult patients (mean age, 37.7 ± 13.5 years) with moyamoya disease, 36 of whom (25.3%) underwent bypass surgery in childhood. Hemorrhagic onset was diagnosed in 31 patients (21.8%). The incidence of microbleeds was evaluated on T2*-weighted or susceptibility-weighted imaging from 3-T magnetic resonance imaging. The patients were subsequently categorized into MBs (microbleeds) or non-MBs groups. Because previous microbleeds potentially lead to hemorrhage, the MBs group was defined as patients with radiographic evidence of bleeding, including asymptomatic microbleeds and/or hemorrhagic onset. The association of baseline characteristics was evaluated. Results Asymptomatic microbleeds were detected in 38 patients (26.8%). Of 31 patients with hemorrhagic onset, 18 had microbleeds, whereas 13 had no microbleeds. Therefore, 51 patients (35.9%) were classified into the MBs group. Bypass surgery in childhood (MBs, 7.8% vs. non-MBs, 35.2%; P Conclusions This study shows the clinical significance of revascularization surgery in childhood associated with a low incidence of asymptomatic microbleeds in adult patients with moyamoya disease. This finding indicates that a newly established bypass can reduce hemodynamic overstress.

Endosaccular coiling is recognized as a feasible method for treating unruptured intracranial aneurysms (UIAs). We retrospectively reviewed cases of UIAs treated by coiling in the Japanese Registry of Neuroendovascular Therapy (JR-NET) 3, a nationwide survey of NET between 2010 and 2014, the beginning period of intracranial stents in Japan. Data were extracted for 6844 UIAs (6619 procedures) from 40,169 registered records of all NETs in the JR-NET 3 databases. The features of the aneurysms and procedures, immediate radiographic findings, procedure-related complications, and clinical outcomes at 30 days after the procedures were assessed. Of 6844 UIAs, 81.8% were located in the anterior circulation. The mean patient age was 61.3 years (72.4% females). Compared with the preceding JR-NET 1 and 2, there were significant increases (P 2) from 2.1% to 2.8%. In conclusion, introduction of neck-bridge stent was associated with an increase in cases of wide-necked aneurysms. However, the ischemic complication rate increased despite the greater use of periprocedural antiplatelet therapy.

Although several studies have recently shown that spinous process-splitting laminectomy (SPSL) maintains lumbar spinal stability by preserving posterior ligament components and paraspinal muscles as compared with conventional laminectomy, evidence is scarce on the treatment outcomes of SPSL limited to lumbar degenerative spondylolisthesis. We herein compare the surgical results and global alignment changes for SPSL versus posterolateral lumbar fusion (PLF) without instrumentation for lumbar degenerative spondylolisthesis.A total of 110 patients with Grade 1 lumbar degenerative spondylolisthesis who had undergone SPSL (47 patients) or PLF (63 patients) with minimum 1-year follow-up were retrospectively enrolled from a single institutional database.Mean operating time per intervertebral level and intraoperative blood loss per intervertebral level were comparable between the SPSL group and PLF group. Japanese Orthopaedic Association scores, Oswestry disability index, and visual analog scale scores were significantly and comparably improved at 1 year postoperatively in both groups as compared with preoperative levels. The numbers of vertebrae with slip progression to Grade 2 and slip progression of 5% or more at 1 year postoperatively were similar between the groups. In the SPSL group, mean pelvic tilt (PT) was significantly decreased at 1 year postoperatively. In the PLF group, mean lumbar lordosis (LL) was significantly increased, while mean sagittal vertical axis, PT, and pelvic incidence-LL were significantly decreased at 1 year after surgery.Compared with PLF without instrumentation, SPSL for Grade 1 lumbar degenerative spondylolisthesis displayed comparable results for slip progression and clinical outcomes at 1 year postoperatively.

Purpose Advanced-stage trapeziometacarpal (TMC) osteoarthritis of the thumb often presents with concomitant hyperextension deformity of the metacarpophalangeal (MCP) joint. Although several studies have reported simultaneous procedures to correct this deformity, the indication for these procedures remains controversial. The purpose of this study was to evaluate changes in the range of motion (ROM) of the thumb MCP joint before and after TMC arthrodesis . Methods We evaluated the functional flexion and extension and functional ROM of the MCP joints during the performance of 10 activities of daily living tasks before and after TMC arthrodesis in 10 thumbs of 9 patients with Eaton stage III TMC osteoarthritis and hyperextension deformity of the MCP joint. Results The mean functional flexion of the MCP joint increased from 26° to 38°, and the mean functional extension of the MCP joint decreased from 16° to 5° of hyperextension. There was no change in the mean total arc of functional ROM of the MCP joint. Conclusions The MCP joint motion shifted from extension to flexion after TMC arthrodesis, and the total arc of functional ROM of the MCP joint was similar before and after arthrodesis. Type of study/level of evidence Therapeutic V

Objective: Cervical pedicle screw (CPS) fixation is widely used for the treatment of cervical spinal instability from various causes; however, there are few reports on the long-term outcomes of this procedure. The present study evaluated the 10-year results of CPS fixation for cervical instability. Methods: The medical records of 13 consecutive patients who underwent computer-guided CPS fixation for cervical instability were reviewed. The mean observation period was 153 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 and 10 years afterwards. Visual analog scale (VAS) scores for neck pain and radiological evidence of adjacent segment degeneration (ASD) at 10 years of follow-up were also assessed. Results: Mean JOA score significantly improved from 9.4 points before surgery to 13.2 points at 5 years after surgery (p

Study Design: Retrospective cohort study.Purpose: This study aimed to evaluate the relationship between C7 plumb line (C7PL) decompensation and the Scoliosis Research Society (SRS) 22-item patient questionnaire scores, including those related to self-image, preoperatively and 2 years after surgery.Overview of Literature: In the surgical treatment of adolescent idiopathic scoliosis (AIS), inferior trunk balance caused by C7PL decompensation can negatively affect patients’ quality of life. However, there are few reports in the literature that describe or clarify how postoperative trunk imbalance affects each SRS-22 domain, including self-image domain scores.Methods: A total of 120 patients with AIS who underwent posterior spinal fusion from August 2006 to March 2017 at our facility and were followed up for 2 years or more were included. Radiological parameters were measured on whole-spine anteroposterior and lateral radiographs. Revised SRS-22 (SRS-22r) values were also recorded. Coronal trunk imbalance was defined as a deviation of ≥2.0 cm between the C7PL and the central sacral vertical line. Patients with and without coronal trunk imbalance at 2 years after surgery were defined as D (+) (decompensation type) and D (-), respectively. Mean SRS-22r values, including function, pain, self-image, mental health, and subtotal were compared between the D (+) and D (-) groups. Logistic regression analysis was performed to detect the preoperative factors related to D (+) using predictors, including curve type, maximum Cobb angle, and coronal trunk imbalance.Results: At 2 years after surgery, the D (+) group had a significantly lower self-image in the domain of SRS-22r scores compared with the D (-) group. Preoperative coronal trunk imbalance was significantly related to D (+) but not to significant changes in the postoperative SRS-22 score in any of the SRS-22 domains.Conclusions: Postoperative C7PL deviation lowers the self-image in patients with AIS. Patients with preoperative coronal trunk imbalance were significantly more likely to be D (+).

Purpose We aimed to evaluate the extent of collagenase clostridium histolyticum (CCH) diffusion in Dupuytren’s contracture (DC) for tissues outside of the contracture cord using Magnetic Resonance Imaging (MRI) immediately after CCH injection. Methods: 10 male patients aged 57–79 with DC of the metacarpophalangeal (MCP) joints were examined. Extension deficits were 10–60°(mean, 34.3) and 0–60°(mean, 26.6) in the MCP and proximal interphalangeal (PIP) joints, respectively. CCH injection was performed according to the standard method. MRI was performed within 15 min of CCH injection. Results: In all 10 cases, the extended area of high-intensity signal change outside of the cord was observed on short-T1 inversion recovery images (STIRs). Continuity from the insertion site was observed in the area of signal change involving the flexor tendon and neurovascular bundle. The signal change area spanned distally and proximally beyond the injection level. The signal change area expanded along the tendon sheath but no signal changes were observed inside the flexor tendon, suggesting the tendon sheath serves as a protective barrier from the CCH solution. After 1 week of injection, the mean decrease in contracture was 32.5°(94.7%) for the MCP joint and 19.8°(74.4%) for the PIP joint. In nine out of 10 cases, the extension deficit was within five degrees of full extension in the affected finger. There was no neurovascular injury or tendon rupture at 3 months of observation. Conclusions: MRI indicated the possible leakage of the drug outside of the cord during the early phase after administration, suggesting that CCH could persistently affect healthy tissues until CCH inactivates its enzyme process.

To investigate the effect of a new remnant preservation technique with a focus on remnant continuity on postoperative femoral and tibial tunnel enlargement after anatomical double-bundle anterior cruciate ligament reconstruction (ACLR).A total of 150 knees were divided into three groups: Preservation Group (Group P: 49 knees), wherein the remnant continuity remained after tunnel creation; Resection Group (Group R: 47 knees), wherein the remaining remnant was resected, and Absent Group (Group A: 54 knees), wherein the remnant had no femoral attachment before tunnel creation. In Group P, the remnant maintained continuity, and the anteromedial (AM) and posterolateral (PL) bundles were positioned anterior and posterior to the remnant, respectively. Computed tomographic scans were performed at 1 week and 1 year after surgery, and the cross-sectional area of each tunnel aperture was measured. Tunnel enlargement was compared among the three groups by one-way analysis of variance (ANOVA) and the Bonferroni test. Univariate and multivariate logistic analyses were performed to identify the risk factors for tunnel enlargement in demographic and radiographic data.For femoral AM tunnels, the tunnel enlargement of Group P was significantly smaller than Groups R and A (p 0.001), femoral PL (p 0.001 vs. R and A), tibial AM (p 0.001 vs. R, 0.002 vs. A), and tibial PL (p 0.001 vs. R, 0.002 vs. A). There was no significant difference between Groups R and A. Multivariate logistic analysis showed that remnant preservation was a significant factor in reducing tunnel enlargement in the femoral AM, femoral PL, tibial AM, and tibial PL.The new remnant-preserving anatomical double-bundle ACLR, which preserves the continuity of the remnant, prevented all bone tunnel enlargement at 1 year postoperatively.Level III.

Study design Case report. Objective Describe the clinical and radiological outcomes of a patient with a piezo-type mechanosensitive ion channel component 2 (PIEZO2)-deficient arthrogryposis receiving surgery for severe kyphoscoliosis. Summary of background data Spinal deformity is a characteristic feature of arthrogryposis due to PIEZO2 gene deficiency, for which surgical correction is indicated when the deformity is progressive to avoid neurological deficits and respiratory impairment. However, there exist few reports on the surgical treatment of spinal deformity in PIEZO2-deficient arthrogryposis, and no therapeutic standards have been established. Methods We retrospectively reviewed a case of proximal junctional kyphosis after posterior spinal fusion for severe kyphoscoliosis in PIEZO2-deficient arthrogryposis. Results The patient was a 13-year-old girl with PIEZO2-deficient arthrogryposis who underwent posterior spinal fusion with an all-pedicle screw construct from T2 to L2 for a preoperative main thoracic curve Cobb angle of 78° and thoracic kyphotic angle of 83°. Postoperative Cobb angle of the main thoracic curve and thoracic kyphotic angle were improved at 11° and 34°, respectively. Although revision surgery was required for neurological deficits from proximal junctional kyphosis, she could walk with a crutch and improvements in clinical questionnaire scores were noted at 2 years and 3 months after surgery. Conclusion Based on the present case, posterior spinal fusion represents a good treatment option for severe spinal deformity in PIEZO2-deficient arthrogryposis. Careful consideration of fusion level is needed to prevent proximal junctional kyphosis. Level of evidence 5.

Differential rod contouring (DRC) is useful for periapical vertebral derotation and decreasing rib hump in patients with thoracic adolescent idiopathic scoliosis (AIS). However, it is unknown whether DRC in the thoracolumbar/lumbar spine also contributes to derotation. We assessed the contributions of rod contouring and of DRC to the reduction of apical axial vertebral body rotation in patients with AIS with thoracolumbar/lumbar curvatures.Forty-five (Lenke type 3 or 4, 17; Lenke type 5 or 6, 28) were analyzed for the contribution of DRC to thoracolumbar/lumbar spinal derotation. Rod contouring was assessed by comparing the preinsertion x-ray with the post-operative CT images. Intraoperative C-arm fluoroscopic scans of the periapical vertebrae of the thoracolumbar/lumbar curve of the scoliosis (135 vertebrae) were taken post-rod rotation (RR) and post-DRC in all patients. Three-dimensional images were automatically reconstructed from the taken x-ray images. The angle of vertebral body rotation in these apical vertebrae was measured, and the contribution of DRC to apical vertebral body derotation and rib hump index (RHi) for lumbar prominence was analyzed.The pre-implantation convex rod curvatures of both Lenke 3/4 and 5/6 groups decreased after surgery. The mean further reductions in vertebral rotation with post-RR DRC were 3.7° for Lenke 3/4 and 4.4° for Lenke 5/6 (P 0.01). Both changes in apical vertebral rotation and in RHi for evaluating lumbar prominence were significantly correlated with the difference between concave and convex rod curvature in preimplantation. Vertebral derotation was significantly higher in curves with a difference20° (P 0.05).DRC following rod rotation contributed substantial additional benefit to reducing vertebral rotation and decreasing lumbar prominence in thoracolumbar/lumbar scoliosis.

Desmoid tumors are monoclonal fibroblastic proliferations arising from soft tissue classified as intra-abdominal, extra-abdominal and abdominal wall types. We present a patient with an intra-abdominal desmoid tumor diagnosed 20 months after laparoscopic resection of rectal cancer. A 70-year-old woman with hematochezia was diagnosed with advanced rectal cancer. Preoperative chemoradiotherapy followed by laparoscopic low anterior resection was performed. During follow-up, a nodular soft-tissue density measuring 28 mm was detected in the presacral region. Metastasis from rectal cancer was diagnosed and four courses of chemotherapy were given, including capecitabine, oxaliplatin and bevacizumab. Computed tomography scan showed that the mass slightly decreased in size and surgical resection was performed. Histopathological examination revealed a proliferation of spindle-shaped cells and collagenous stroma diagnosed as a desmoid tumor. This report highlights the possibility of a desmoid tumor in the differential diagnosis of an intra-abdominal mass found during follow-up after resection of colorectal cancer including following laparoscopic resection.

This is a retrospective single-center and single-surgeon study.We investigated the correlation between lower instrumented vertebra (LIV) and spinal mobility 2 years after posterior spinal fusion with pedicle screws for adolescent idiopathic scoliosis (AIS) for optimal LIV selection.Spinal motion can become limited in scoliosis patients who undergo posterior spinal fusion. However, few reports exist on spinal mobility after posterior spinal fusion for AIS and the relationship between the LIV and mobility is unknown. We hypothesize that mobility limitation increases as the LIV is moved inferiorly.Of 72 consecutive patients who received posterior spinal fusion using pedicle screws for AIS between October 2009 and August 2015, 66 patients (5 male and 61 female, mean age: 14.9 y) were enrolled.In total, 66 patients were retrospectively reviewed after stratification according to LIV level. Follow-up rate was 91.7%. Patients were examined for the fingertip-to-floor distance (FFD) before and 2 years after surgery. FFD was measured from the tips of the middle fingers to the floor with the barefoot subject bent maximally forward and the feet together and knees straight. Clinical outcome was assessed using Scoliosis Research Society-22 patient questionnaire (SRS-22r) scores and a visual analog scale for low back pain before and at 2 years postoperatively.The median number of fused vertebrae was 9 (range: 4-15). The LIV was T11-12 in 15 patients, L1 in 11 patients, L2 in 10 patients, and L3 in 30 patients. The median decrease in FFD according to LIV at 2 years after surgery was T11-12: 0 cm, L1: 0 cm, L2: 5.5 cm, and L3: 10 cm. Thus, limited FFD became significantly more severe as the LIV was moved downwards (P0.01). There were no significant correlations between limited FFD and SRS-22r or pain visual analog scale scores at 2 years postoperatively.FFD became significantly more restricted as the LIV was moved inferiorly but clinical results appeared unaffected by limited FFD.

Long fusion to the sacrum with iliac screws can decrease pelvic incidence (PI). Considering the physiological range of movement of the sacroiliac joint, this decrease may be relatively extreme. The purpose of the study was to determine changes in pelvic morphology after orthopedic surgery using long fusion with iliac screws, and examine the relationship between changes in PI and morphology. We included data from 80 consecutive patients who underwent corrective surgery for adult spine deformity (72 female and 8 male; mean age: 71.1 years). We examined preoperative and early postoperative full-standing X-ray images and pelvic computed tomography of the patients and compared the following: (1) pre- and postoperative pelvic measurements including PI, (2) correlations between change of PI, iliac angle, and distance between posterior superior iliac spines (DPSIS). After surgery, PI decreased significantly (− 3.3°, 95% confidence interval [95%CI] − 4.3° to − 2.3°, P

Reducing the number of screw insertions while maintaining good clinical outcomes can improve the efficiency and cost-effectiveness of scoliosis surgery. However, the optimal minimum number of pedicle screws remains unclear. This study searched for factors to estimate the fewest number of pedicle screws required between end vertebrae in relation to preoperative main thoracic curve flexibility.Sixty-nine subjects (4 male and 65 female, mean age: 14.8 ± 2.5 years) who underwent skip pedicle screw fixation for Lenke type 1-4 or 6 curves and were followed for at least 1 year were enrolled. Intervention technique was selected according to the size and flexibility of the preoperative main thoracic curve. Surgery-related variables included pedicle screw number, rod material and diameter, and extent of Ponte osteotomy. The effect on postoperative correction angle (i.e., the difference between the preoperative supine position maximum bending and postoperative standing Cobb angles of the main thoracic curve) according to surgical intervention technique was estimated using multiple linear mixed regression models with the preoperative supine position maximum bending correction angle (i.e., the difference between the standing preoperative and supine position maximum bending Cobb angles) as a random effect.The preoperative maximum bending correction angle was 8-42° and had a moderate negative correlation with postoperative correction angle (r = -0.65, P 0.01). Multivariate analysis revealed a 1.7° (95% CI 0.7-2.6; P 0.01) correction gain per single-screw insertion and a 1.8° (95% CI 0.5-3.1; P 0.01) gain per intervertebral level in Ponte osteotomy.The number of pedicle screws necessary to correct main thoracic adolescent idiopathic scoliosis curves can be estimated by calculating correction gains of 1.7° per pedicle screw and 1.8° per Ponte osteotomy intervertebral level. Based on these results, it may be possible to reduce invasiveness and cost for patients requiring a smaller degree of correction.

STUDY DESIGN Retrospective, single-center, single-surgeon study. OBJECTIVE This study investigated screw perforation rate according to surface registration accuracy in pedicle screw fixation using a CT-based navigation system for adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA Posterior spinal fusion for scoliosis correction using pedicle screws is widely adopted but carries a risk of serious neurovascular or visceral structure events. To attempt to avoid these complications, we have been using a computed tomography (CT)-based navigation system during screw insertion, although insufficient surface registration accuracy may be a reason for some screw perforations. METHODS We evaluated 116 AIS patients (9 male and 107 females; mean±standard deviation age: 15.2±2.3 y) who had received pedicle screw fixation guided by a CT-based navigation system between August 2007 and December 2017. Screw perforation rate was evaluated in relation to surface registration accuracy and cut-off values were determined by receiver operating characteristic (ROC) curves. RESULTS A total of 1553 pedicle screws were inserted into T2-L4 vertebrae using CT-based navigation system. The respective overall perforation rates for grade 2 or 3 and grade 3 perforations by surface registration accuracy were 0.2 mm: 0% and 0%; 0.3 mm: 3.5% and 0%; 0.4 mm: 3.5% and 0.8%; 0.5 mm: 8.0% and 3.5%; 0.6 mm: 6.7% and 2.7%; 0.7 mm: 8.9% and 3.8%; 0.8 mm: 9.3% and 6.7%; and 0.9 mm: 9.3% and 4.7%. ROC curve analysis revealed a cut-off surface registration accuracy of 0.5 mm. The major screw perforation rate for a surface registration accuracy of ≥0.5 mm was significantly higher than that for