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Objective: This study was designed to identify the presence, type and origin of bacteria adjacent to the metal implant in the infected region in a canine model of pyogenic vertebral osteomyelitis treated with single-stage anterior autogenous bone grafting and instrumentation., Methods: Dogs with pyogenic spondylodiscitis underwent one-stage debridement, autogenous bone grafting and titanium plate instrumentation and perioperative antibiotic therapy. The implants and adjacent vertebral bones were removed surgically at various postoperative time points (4, 8, 12 and 24 weeks) for bacteria detection. Bacteria were detected from retrieved spinal implants as well as surrounding bones by culture and/or pyrosequencing methods in 17 (85%) of all 20 animals. The positive rate for bacteria presence was 45% by culture and 80% by pyrosequencing method., Results: Radiological or macroscopic examination showed no signs for infection recurrence in any animal regardless of bacteria presence at the surgical site. However, organism identical with the causative bacterium for spinal infection was found in only two of nine culture-positive animals., Conclusion: Within the confines of the study, the use of metallic implants in an infected area did not lead to a clinically relevant infection although bacteria may exist at the surgical site. The use of metallic implants in an infected area of the spine is safe. The metallic implants may not be the “culprit” for the persistence or recurrence of infection.

Purpose: The AO Spine Classification Group was established to propose a revised AO spine injury classification system. This paper provides details on the rationale, methodology, and results of the initial stage of the revision process for injuries of the thoracic and lumbar (TL) spine., Methods: In a structured, iterative process involving five experienced spine trauma surgeons from various parts of the world, consecutive cases with TL injuries were classified independently by members of the classification group, and analyzed for classification reliability using the Kappa coefficient (κ) and for accuracy using latent class analysis. The reasons for disagreements were examined systematically during review meetings. In four successive sessions, the system was revised until consensus and sufficient reproducibility were achieved., Results: The TL spine injury system is based on three main injury categories adapted from the original Magerl AO concept: A (compression), B (tension band), and C (displacement) type injuries. Type-A injuries include four subtypes (wedge-impaction/split-pincer/incomplete burst/complete burst); B-type injuries are divided between purely osseous and osseo-ligamentous disruptions; and C-type injuries are further categorized into three subtypes (hyperextension/translation/separation). There is no subgroup division. The reliability of injury types (A, B, C) was good (κ = 0.77). The surgeons' pairwise Kappa ranged from 0.69 to 0.90. Kappa coefficients κ for reliability of injury subtypes ranged from 0.26 to 0.78., Conclusions: The proposed TL spine injury system is based on clinically relevant parameters. Final evaluation data showed reasonable reliability and accuracy. Further validation of the proposed revised AO Classification requires follow-up evaluation sessions and documentation by more surgeons from different countries and backgrounds and is subject to modification based on clinical parameters during subsequent phases.

Objective: Clinical outcomes of the stand-alone cage have been encouraging when used in anterior cervical discectomy and fusion (ACDF), but concerns remain regarding its complications, especially cage subsidence. This retrospective study was undertaken to investigate the long-term radiological and clinical outcomes of the stand-alone titanium cage and to evaluate the incidence of cage subsidence in relation to the clinical outcome in the surgical treatment of degenerative cervical disc disease., Methods: A total of 57 consecutive patients (68 levels) who underwent ACDF using a titanium box cage for the treatment of cervical radiculopathy and/or myelopathy were reviewed for the radiological and clinical outcomes. They were followed for at least 5 years. Radiographs were obtained before and after surgery, 3 months postoperatively, and at the final follow-up to determine the presence of fusion and cage subsidence. The Cobb angle of C2-C7 and the vertebral bodies adjacent to the treated disc were measured to evaluate the cervical sagittal alignment and local lordosis. The disc height was measured as well. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score for cervical myelopathy, before and after surgery, and at the final follow-up. The recovery rate of JOA score was also calculated. The Visual Analogue Scale (VAS) score of neck and radicular pain were evaluated as well. The fusion rate was 95.6% (65/68) 3 months after surgery., Results: Successful bone fusion was achieved in all patients at the final follow-up. Cage subsidence occurred in 13 cages (19.1%) at 3-month follow-up; however, there was no relation between fusion and cage subsidence. Cervical and local lordosis improved after surgery, with the improvement preserved at the final follow-up. The preoperative disc height of both subsidence and non-subsidence patients was similar; however, postoperative posterior disc height (PDH) of subsidence group was significantly greater than of non-subsidence group. Significant improvement of the JOA score was noted immediately after surgery and at the final follow-up. There was no significant difference of the recovery rate of JOA score between subsidence and non-subsidence groups. The recovery rate of JOA score was significantly related to the improvement of the C2-C7 Cobb angle. The VAS score regarding neck and radicular pain was significantly improved after surgery and at the final follow-up. There was no significant difference of the neck and radicular pain between both subsidence and non-subsidence groups., Conclusions: The results suggest that the clinical and radiological outcomes of the stand-alone titanium box cage for the surgical treatment of one- or two-level degenerative cervical disc disease are satisfactory. Cage subsidence does not exert significant impact upon the long-term clinical outcome although it is common for the stand-alone cages. The cervical lordosis may be more important for the long-term clinical outcome than cage subsidence.

Various mechanical stresses in vivo induce disc cell apoptosis and intervertebral disc (IVD) degeneration, but the underlying molecular mechanism is not fully known. The aim of this study was to investigate the role of endoplasmic reticulum stress in cyclic stretch-induced apoptosis of rat annulus fibrosus (AF) cells. Flexercell Tension Plus system was used to apply cyclic stretch to rat annulus fibrosus cells at a frequency of 0.5 Hz with 20% elongation for 12, 24, 36, or 48 h. Apoptosis was detected by flow cytometry, and nuclei morphologic changes were visualized by Hoechst 33258 staining and caspase-8, 9 activity assays. The expression of the markers of endoplasmic reticulum stress including CHOP, GRP78, and caspase-12 were determined by RT-PCR and Western blot. Mitochondrial membrane potential change was observed by JC-1 staining in situ. In addition, the levels of the nitric oxide (NO) were determined with the Griess reaction and fluorescence staining. The results indicated that cyclic stretch at a frequency of 0.5 Hz with 20% elongation-induced apoptosis in rat AF cells. Prolonged exposure of the unphysiologically cyclic stretch to AF cells caused NO overproduction, up-regulation of endoplasmic reticulum stress markers including CHOP, GRP78, and caspase-12, depolarization of mitochondria and activation of caspase-9. However, cyclic stretch at this level had no effect on caspase-8 activity. In addition, specific inhibitor of caspase-12 (Z-ATAD-FMK) and caspase-9 (Z-LEHD-FMK) partly suppressed cyclic stretch-induced AF cell apoptosis and the anti-apoptotic effects of the caspase inhibitors were additive. Our data suggest that endoplasmic reticulum stress, likely mediated by NO, contributes to the AF cell apoptosis induced by cyclic stretch in addition to the mitochondrial pathway. These findings could be helpful to understand the mechanism of disc cell apoptosis, the root cause of IVD degeneration.

Cervical spondylotic amyotrophy is characterized with weakness and wasting of upper limb muscles without sensory or lower limb involvement. Two different mechanisms have been proposed in the pathophysiology of cervical spondylotic amyotrophy. One is selective damage to the ventral root or the anterior horn, and the other is vascular insufficiency to the anterior horn cell. Cervical spondylotic amyotrophy is classified according to the most predominantly affected muscle groups as either proximal-type (scapular, deltoid, and biceps) or distal-type (triceps, forearm, and hand). Although cervical spondylotic amyotrophy always follows a self-limited course, it remains a great challenge for spine surgeons. Treatment of cervical spondylotic amyotrophy includes conservative and operative management. The methods of operative management for cervical spondylotic amyotrophy are still controversial. Anterior decompression and fusion or laminoplasty with or without foraminotomy is undertaken. Surgical outcomes of distal-type patients are inferior to those of proximal-type patients.

Posterior operative approach has been the standard treatment for cervical compressive myelopathy, and axial pain after laminoplasty or laminectomy as a postoperative complication is now gradually receiving more and more attention. The objective of this study was to provide a systematic review of the current understanding of axial pain after cervical laminoplasty and laminectomy, and summarize clinical features, influence factors and preventive measures of axial pain after posterior decompressive surgery based on a review of literature published in the English language. Axial pain distributes over nuchal, periscapular and shoulder regions. Posterior surgery is not the major cause of axial pain, but axial pain can be worsened by the procedure. There are many clinical factors that influence postoperative axial pain such as age, preoperative axial pain, different surgical technique and postoperative management, but most of them are still controversial. Several surgical modifications have been innovated to reduce axial pain. Less invasive surgery, reconstruction of the extensor musculature, avoiding detachment of the semispinalis cervicis muscle and early removal of external immobilization have proved to be effective. Axial pain is under the influence of multiple factors, so comprehensive methods are required to reduce and avoid the postoperative axial pain. Because of methodological shortcomings in publications included in this systematic review, different results from different studies may be produced due to differences in study design, evaluation criteria, sample size, and incidence or severity of axial pain. More high-quality studies are necessary for drawing more reliable and convincing conclusions.

Extreme lateral lumbar disc herniations (ELLDHs) occur more frequently among elderly patients, with a peak incidence in the sixth decade, and are rarely found in children. The patient presented is a 12-year-old boy with a 3-month history of right-sided leg pain. Computerized tomography and magnetic resonance imaging demonstrated an extreme lateral disc herniation on the right at L4-L5 with compression of the L4 nerve root. He subsequently underwent removal of extreme lateral herniated disc through an intertransverse approach under general anesthesia. At 11-month follow-up, the patient maintained resolution of preoperative symptoms and a neurological examination revealed no sensory or motor deficit. Surgical intervention may be indicated for patients with ELLDHs that fail with conservative treatment.

Traumatic posterior atlantoaxial dislocation without related fracture of the odontoid process is very rare, and only ten cases have been previously reported. The objective of this paper was to describe a case of traumatic posterior atlantoaxial dislocation without related fracture of the odontoid process, and its management with atlantoaxial transarticular screw fixation and bony fusion through an anterior retropharyngeal approach, and to review the relevant literature. The patient's medical and radiographic history is reviewed as well as the relevant medical literature. Posterior atlantoaxial dislocation was confirmed in a 48-year-old male struck by an automobile through conventional radiography, computed tomography and magnetic resonance imaging. No related fracture of the odontoid process or neurological deficit was found in this patient. Transarticular screw fixation of the atlantoaxial articulation through anterior retropharyngeal approach was performed after several unsuccessful attempts of closed reduction. At the latest follow-up, the lateral cervical spine radiography in flexion and extension demonstrated no instability of the atlantoaxial complex 21 months after the operation. In conclusion, patients with posterior atlantoaxial dislocation without fracture may survive with few or no-long term neurological deficit. Routine CT and MRI of the cervical spine should be carried out in patients with head or neck trauma to prevent missing of this rare clinical entity. Transarticular screw fixation of the atlantoaxial articulation through anterior retropharyngeal approach is safe and useful in case the management of dislocation is unsuccessful under closed reduction.

Adolescent idiopathic scoliosis (AIS) is a pathological entity of unknown etiology. The causes of osteoporosis or osteopenia in AIS remain undetermined. Whether poor bone quality is an etiologic factor remains controversial. To determine the correlation between low bone mineral status and AIS, a review of literature was performed. After a literature search from 1966 to June 2007 (using Medline, EMBASE, Cochrane DSR, ACP Journal Club, DARE, CCTR, CINAHL and hand searches of references) for studies regarding low bone mineral status and AIS, 20 studies meeting the inclusion criteria were reviewed in terms of the appropriateness of valuation technique, the validity of descriptive system, the number and type of respondents, and overall quality of the studies. Nearly all investigations demonstrated that low bone mineral density (BMD) was a generalized phenomenon and a systematic disorder in AIS. The prevalence of AIS with osteoporosis is approximately 20-38%. The follow-up studies indicated that osteopenia in patients with AIS may be a persistent phenomenon. BMD could be affected by the mechanical loading and lower bone mineral mass is always associated with lower bone strength. The spinal architecture associated with the osteopenia may aggravate the spinal deformity. However, with regard to the concave and convex femoral neck BMD values, and the correlation of BMD to scoliosis parameters, the results remain inconsistent. Bracing may not result in permanent loss of bone mineral mass. The effect of the eccentric tension-compression environments on BMD, the correlation of BMD with scoliosis parameters and the effect of bracing on BMD should be investigated further in prospective, randomized and longitudinal follow-up studies.

Modic changes (MC) are a common phenomenon on magnetic resonance imaging (MRI) in spinal degenerative diseases and strongly linked with low back pain (LBP). Histology, radiology, potential mechanisms, natural history and clinical studies of MC has formed the foundation on which our understanding of spinal degenerative diseases is built. The objective of this study was to provide a review of recent important advances in the study of MC and their clinical significance. This review article summarizes these studies, by delineating the possible mechanisms, and raising doubts and new questions. The related aspects such as discography and differential diagnosis with spinal infection and tumor on MRI are also discussed. Although most of researchers believe that MC are common findings in patients with spinal degenerative diseases and have an association with discogenic LBP, different results between studies may be produced from the differences in study design, inclusion criteria, and sample size. How the present knowledge of MC affects the management of spinal degenerative diseases remains unclear. Further studies of MC will explore therapeutic possibilities for future treatments of spinal degenerative diseases.

For patients with ossification of the posterior longitudinal ligament (OPLL) who have neurological-symptoms, surgery is necessary but not always effective. Various clinical factors influence the surgical outcome. The studies identifying these factors have been inconclusive and conflicting. It is essential for surgeons to understand the significance of the factors and choose the optimal therapeutic strategy for OPLL. The objective of this review is to determine the clinical factors predictive of the surgical outcome of cervical OPLL. The authors conducted a review of literature published in the English language. They examined studies in which the correlation between clinical factors and outcome were statistically evaluated. The results showed that the traverse area of the spinal cord, the spinal cord-evoked potentials (SCEPs), the increase of the range of motion in the cervical spine (ROM), diabetes, history of trauma, the onset of ossification of the ligament flavum (OLF) in the thoracic spine, snake-eye appearance (SEA) and incomplete decompression may be predictive factors. Age at surgery seems to be closely related to the outcome of posterior surgical procedure. Whether the neurological score, OPLL type, pre-operative duration of symptoms, focal intra-medullar high signal intensity in T2-weighted (IMHSI) and progression of OPLL or kyphosis and expansion of the spinal canal predict the surgical outcome remains unclear. The use of uniform neurological score and proper statistic analysis should facilitate comparison of data from different studies. It is important to analyze the effect of each factor on groups with different surgical procedures as well as patients with different compressive pathology. Research on the etiology and pathology of cervical myelopathy due to OPLL should be helpful in precisely understanding these clinical factors and predicting surgical outcome.

Anterior radical debridement and bone grafting is popular in the treatment of pyogenic infection of the spine, but there remains great concern of placing instrumentation in the presence of infection because of the potentiality of infection recurrence after surgery. The objective of this study was to prospectively evaluate the efficacy and safety of anterior instrumentation in patients who underwent simultaneous anterior debridement and autogenous bone grafting for the treatment of pyogenic vertebral osteomyelitis. The series consisted of 22 consecutive patients who were treated with anterior debridement, interbody fusion with autogenous bone grafting and anterior instrumentation for pyogenic vertebral osteomyelitis of thoracic and lumbar spine. The patients were prospectively followed up for a minimum of 3 years (average 46.1 months; range 36-74 months). Data were obtained for assessing clinically the neurological function and pain and radiologically the spinal alignment and fusion progress as well as recurrence of the infection. All the patients experienced complete or significant relief of back pain with rapid improvement of neurological function. Kyphosis was improved with an average correction rate of 93.1% (range 84-100%). Solid fusion and healing of the infection was achieved in all the patients without any evidence of recurrent or residual infection. The study shows that combined with perioperative antibiotic regimen, anterior instrumentation is effective and safe in the treatment of pyogenic vertebral osteomyelitis of thoracic and lumbar spine directly following radical debridement and autogenous bone grafting.

Non-insulin-dependent diabetes is known as a risk factor of ossification of posterior longitudinal ligament, but the mechanism has not been well understood. We hypothesized that hyperglycemia, as a typical characteristic of diabetes, is closely associated with ligament hypertrophy in ossification of posterior longitudinal ligament. In this in vitro study, we investigated the effect of high glucose on collagen synthesis and transforming growth factor-beta1 (TGF-beta1) production using cells isolated from rat cervical posterior longitudinal ligament. The cells were subjected to high D-glucose concentration (25 mM) media for 4 days. Notable increases were observed in gene expression and protein synthesis of collagen types I, III in the cells. The increase was inhibited in the presence of anti-TGF-beta1 antibodies. Production of TGF-beta1 by the cells was also increased significantly by high glucose concentration. Exogenous application of TGF-beta1 was confirmed to increase collagen synthesis of the cells. These data suggested that high glucose could promote collagen synthesis in the posterior longitudinal ligament mainly via endogenous TGF-beta1, resulting in hypertrophy of the ligament.

A variety of bone graft substitutes, interbody cages, and anterior plates have been used in cervical interbody fusion, but no controlled study was conducted on the clinical performance of beta-tricalcium phosphate (beta-TCP) and the effect of supplemented anterior plate fixation. The objective of this prospective, randomized clinical study was to evaluate the effectiveness of implanting interbody fusion cage containing beta-TCP for the treatment of cervical radiculopathy and/or myelopathy, and the fusion rates and outcomes in patients with or without randomly assigned plate fixation. Sixty-two patients with cervical radiculopathy and/or myelopathy due to soft disc herniation or spondylosis were treated with one- or two-level discectomy and fusion with interbody cages containing beta-TCP. They were randomly assigned to receive supplemented anterior plate (n = 33) or not (n = 29). The patients were followed up for 2 years postoperatively. The radiological and clinical outcomes were assessed during a 2-year follow-up. The results showed that the fusion rate (75.0%) 3 months after surgery in patients treated without anterior cervical plating was significantly lower than that (97.9%) with plate fixation (P < 0.05), but successful bone fusion was achieved in all patients of both groups at 6-month follow-up assessment. Patients treated without anterior plate fixation had 11 of 52 (19.2%) cage subsidence at last follow-up. No difference (P > 0.05) was found regarding improvement in spinal curvature as well as neck and arm pain, and recovery rate of JOA score at all time intervals between the two groups. Based on the findings of this study, interbody fusion cage containing beta-TCP following one- or two-level discectomy proved to be an effective treatment for cervical spondylotic radiculopathy and/or myelopathy. Supplemented anterior plate fixation can promote interbody fusion and prevent cage subsidence but do not improve the 2-year outcome when compared with those treated without anterior plate fixation.

Pyogenic vertebral osteomyelitis responds well to conservative treatment at early stage, but more complicated and advanced conditions, including mechanical spinal instability, epidural abscess formation, neurologic deficits, and refractoriness to antibiotic therapy, usually require surgical intervention. The subject of using metallic implants in the setting of infection remains controversial, although more and more surgeons acknowledge that instrumentation can help the body to combat the infection rather than to interfere with it. The combination of radical debridement and instrumentation has lots of merits such as, restoration and maintenance of the sagittal alignment of the spine, stabilization of the spinal column and reduction of bed rest period. This issue must be viewed in the context of the overall and detailed health conditions of the subjecting patient. We think the culprit for the recurrence of infection is not the implants itself, but is the compromised general health condition of the patients. In this review, we focus on surgical treatment of pyogenic vertebral osteomyelitis with special attention to the role of spinal instrumentation in the presence of pyogenic infection.

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated by percutaneous anterior odontoid screw fixation under fluoroscopic guidance from March 2000 to May 2002. Their mean age at presentation was 37.2 years (with a range from 21 to 55 years). Six cases were Type II and four were Type III classified by the Anderson and D'Alonzo system. The operation was successfully completed without technical difficulties, and without any soft tissue complications such as esophageal injury. No neurological deterioration occurred. Satisfactory results were achieved in all patients and all of the screws were in good placement. After a mean follow-up of 15.7 months (range 10-25 months), radiographic fusion was documented for 9 of 10 patients (90%). Neither clinical symptoms nor screw loosening or breakage occurred. Our preliminary clinical results suggest that the percutaneous anterior odontoid screw fixation procedure using a new instrument and fluoroscopy is technically feasible, safe, useful, and minimally invasive.

Ossification of the spinal ligaments (OSL) is a pathologic condition that causes ectopic bone formation and subsequently results in various degrees of neurological deficit, but the etiology of OSL remains almost unknown. Some systemic hormones, such as 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin and leptin, and local growth factors, such as transforming growth factor-beta (TGF-beta), and bone morphogenetic protein (BMP), have been studied and are thought to be involved in the initiation and development of OSL. This review article summarizes these studies, delineates the possible mechanisms, and puts forward doubts and new questions. The related findings from studies of genes and target cells in the ligament of OSL are also discussed. Although these findings may be helpful in understanding the pathogenesis of OSL, much more research needs to be conducted in order to investigate the nature of OSL.

The most common pattern among thoracolumbar burst fractures involves failure of the superior vertebra end-plate. There have been many biomechanical studies of thoracolumbar burst fractures, but the biomechanics related to the internal architecture of thoracolumbar vertebrae has been rarely documented. The objective of this study was to test the hypotheses that distribution of the bone mineral density (BMD) of the thoracolumbar spine is related to the stress concentration in this region and therefore, supports the pattern of burst fractures that occur most commonly. We measured spinal BMD of the first lumbar vertebra in 22 individuals using quantitative computed tomography (QCT) in three levels. At each level, the BMD for the trabecular compartment was determined from each of six sites and from one site within each pedicle. Thus the trabecular density was measured at a total of 20 sites for each person. The highest average QCT BMD was in the pedicle (sites 13 and 14), whereas the BMD was abruptly decreased at the posterior part of the vertebral body near the pedicles. The results of the study indicate that stress concentration of the spine related to the regional variation in vertebral bone density may be implicated in the biomechanical mechanism underlying thoracolumbar burst fractures. This finding may be correlated with the injury mechanism of thoracolumbar burst fractures and of clinical significance.

During the past 30 years various treatment protocols for hangman's fractures have been attempted. In order to guide the management of hangman's fractures, different classifications have been introduced. However, opinions on operative or nonoperative treatment have not yet been solidified. To evaluate both conservative and operative management of hangman's fractures in the published literature and to provide appropriate guidelines for treatment of hangman's fractures, a systematic review of the literature regarding the management of hangman's fractures was performed. An English literature search from January 1966 to January 2004 was completed with reference to treatment of hangman's fractures. The classification for treatment guidance from the literature was also reviewed. Regarding a primary therapy for hangman's fractures, there were 20 papers (62.5%) that advocated for a conservative treatment and 11 of the remaining 12 papers suggested that conservative treatment was suitable for some stable fractures. The classification of Effendi et al. modified by Levine and Edwards was used widely. Most hangman's fractures could be managed successfully with traction and external immobilization, especially in Effendi Type I, Type II and Levine-Edwards Type II fractures. It is necessary for Levine-Edwards Type IIa and III fractures to be treated with rigid immobilization. Only for some stable Type I and Levine-Edwards Type II injuries, nonrigid external fixation alone was sufficient. Rigid immobilization alone was necessary for most cases. Surgical stabilization is recommended in unstable cases when there is the possibility of later instability, such as Levine-Edwards Type IIa and III fractures with significant dislocation. The classification system proposed by Effendi et al. and modified by Levine and Edwards provided a clinically reasonable guideline for successful management of hangman's fractures.

Forty-six patients with lumbar spondylolysis and mild isthmic spondylolisthesis were managed with direct repair of the defect with or without facet joint fusion in the affected segment. There were 24 males and 22 females, ranging in age from 15 to 56 years (average, 38.2 years). These patients had experienced clinical symptoms due to spondylolysis for between 4 months and 20 years (average, 5.3 years). Of 46 patients, 28 had no spondylolisthesis, 11 had Meyerding grade I vertebral slippage and 7 had grade II. Direct repair of 98 defects was performed on these patients. Twenty-six patients, in whom the disc adjacent to the defect was determined as degenerative by magnetic resonance imaging (MRI), simultaneously underwent facet joint fusion; 17 in one segment and 9 in two segments. The average period of follow-up was 50 months (24-92 months). Ninety-four defects achieved bony healing. As a result, 28 patients were graded as having an excellent outcome, 15 good, and 3 fair. Bone grafting in the defects achieves union between the loose lamina and the anterior element of lumbar vertebrae, and reconstructs the anatomic structure and physiologic functions of the lumbar vertebrae. There was no significant difference in outcome between the spondylolytic/spondylolisthetic patients with non-degenerative disc, who were treated with direct repair of defect only, and those with degenerative disc, who additionally underwent a fusion procedure (P > 0.05). The present series demonstrates a satisfactory result and a high rate of bony healing of the pars defect by this operative procedure in patients with lumbar spondylolysis and mild isthmic spondylolisthesis. Preoperative assessment of the disc degeneration with MRI is of great assistance in making the protocol choice of whether to opt for fusion.

Fifty-seven consecutive patients treated surgically for nonunited fractures of the odontoid process were reviewed. All patients presented late, exhibiting neurological deficits subsequent to nonunion. Delay in presentation was between 6 and 120 months (mean 32 months) after the original injury, due to missed diagnosis or inappropriate management. Seven patients who were reduced in traction underwent a Gallie atlantoaxial fusion. In the remaining 50 patients who were unreducible, an occipitocervical arthrodesis was performed. They were followed up for a minimum of 2 years, except one who died from postoperative respiratory failure. All patients obtained a solid bony union, including two in whom nonunion occurred following atlantoaxial fusion, and occipitocervical fusion was added as a rescue. Thirty-eight patients achieved excellent neurological recovery, nine still had some disability, five retained their neurological deficits and two reported a deterioration. In two patients, a recurrence in a traumatic episode was experienced long after a resolution. Our findings demonstrate that occipitocervical arthrodesis is preferable for unreducible subluxation or instability of atlantoaxial articulation in nonunion of odontoid fractures.

Lumbar spinal stenosis and lumbar disc herniation are usually regarded as two pathogenetically different conditions, but in the literature lumbar disc herniation in patients with developmental spinal stenosis has been rarely documented. In a clinical retrospective study, 42 lumbar disc herniations with developmental spinal stenosis were reported and analyzed. Discectomy was performed after laminotomy. The patients were followed-up for an average of 4.4 years (range 2-7 years). The preoperative symptoms disappeared completely in 28 patients, in 13 patients some degree of backache remained although their nerve root pain had been relieved, and in 1 patient intermittent claudication reappeared after 6 years resolution of their preoperative pain. We conclude that when developmental spinal stenosis is combined with disc herniation, discectomy through laminotomy rather than laminectomy is usually sufficient for decompression.