Bacteria detected after instrumentation surgery for pyogenic vertebral osteomyelitis in a canine model.

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.

Stage specific effect of leptin on the expressions of estrogen receptor and extracellular matrix in a model of chondrocyte differentiation.

Endochondral ossification is a dynamic process. The interaction between leptin and estrogen in this process is complicated. Whether there is a stage specific crosstalk between leptin and estrogen in the differentiation process of the chondrocytes in the growth plate remains unknown. The aim of our study was to investigate the effect of leptin on the expression of estrogen receptors and extracellular matrix in ATDC5 cells, an in vitro model of endochondral ossification. First, we quantified the physiological expressions of estrogen receptors α, ß (ERα, ERß), leptin receptor (Ob-Rb), type II and type X collagens in definite stages of endochondral ossification in ATDC5 cells using real-time PCR. Dynamic and stage specific expression characteristics of these target genes were observed. Simultaneous expressions of Ob-Rb with ERα or ERß in ATDC5 cells were also found with dual-label confocal immunofluorescency. Then using Western blotting analysis and/or real-time PCR, we detected that, leptin treatment up-regulated the expressions of ERα, ERß and type II collagen, but down-regulated type X collagen expression and the ERα/ERß ratio in the chondrogenic differentiation stage. Meanwhile, leptin down-regulated the expressions of ERα, type II and type X collagens, and the ERα/ERß ratio, but up-regulated the expression of ERß in the hypertrophic differentiation stage. Significant positive correlation existed between ERα and type II collagen expression, and between the ratio of ERα/ERß and type X collagen production. In summary, the crosstalk between leptin and estrogen receptor might be differentiation stage specific in ATDC5 cells.

Difference in subchondral cancellous bone between postmenopausal women with hip osteoarthritis and osteoporotic fracture: implication for fatigue microdamage, bone microarchitecture, and biomechanical properties.

OBJECTIVE: Osteoarthritis (OA) and osteoporosis (OP) of the hip rarely occur in the same patient. The purpose of this study was to determine whether this difference might be attributable to the different quantity and quality of subchondral cancellous bone in the two conditions. METHODS: Subchondral cancellous bone from the femoral head was obtained at the time of hip arthroplasty from 60 postmenopausal women, 30 with OA and 30 with OP. In each group, 10 specimens were subjected to compressive fatigue loading and 20 were left nonloaded. Specimens were examined by compressive mechanical testing, micro-computed tomography scanning, fluorescence microscopy, and nanoindentation techniques. RESULTS: Both the ultimate stress and the elastic modulus of cancellous bone from OA patients were significantly higher than those of cancellous bone from OP patients (P < 0.05). Compared to cancellous bone from OP patients, the bone volume fraction and trabecular thickness were significantly increased, but bone matrix mineralization was significantly decreased, in cancellous bone from OA patients (P < 0.05 for each comparison). The microcrack density was significantly higher in OP cancellous bone than in OA cancellous bone (P < 0.001), irrespective of fatigue loading. In addition, fatigue loading resulted in a significant increase in microcrack density in both OA and OP cancellous bone (P < 0.001). There was no significant difference in nanoindentation elastic modulus and hardness between cancellous bone from OA and OP patients, as well as between bones with and without fatigue loading. CONCLUSION: The difference in mechanical properties between OA and OP cancellous bone is attributed to different bone mass and bone structure. OP cancellous bone is susceptible to fatigue damage due to insufficient structure. However, increased bone volume and plate-like structure provide OA cancellous bone a superior capacity to resist fatigue damage.

AO spine injury classification system: a revision proposal for the thoracic and lumbar spine.

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.

Leptin regulates estrogen receptor gene expression in ATDC5 cells through the extracellular signal regulated kinase signaling pathway.

Both estrogen and leptin play an important role in the regulation of physiological processes of endochondral bone formation in linear growth. Estrogen receptors (ERα and ERß) are known as members of the superfamily of nuclear steroid hormone receptors and are detected in all zones of growth plate chondrocytes. They can be regulated in a ligand-independent manner. Whether leptin regulates ERs in the growth plate is still not clear. To explore this issue, chondrogenic ATDC5 cells were used in the present study. Messenger RNA and protein analyses were performed by quantitative PCR and Western blotting. We found that both ERα and ERß were dynamically expressed during the ATDC5 cell differentiation for 21 days. Leptin (50 ng/ml) significantly upregulated ERα and ERß mRNA and protein levels 48 h after leptin stimulation (P<0.05) at day 14. The up-regulation of ERα and ERß mRNA by leptin was shown in a dose-dependent manner, but the most effective dose of leptin was different (100 and 1,000 ng/ml, respectively). Furthermore, we confirmed that leptin augmented the phosphorylation of ERK1/2 in a time-dependent manner. A maximum eightfold change was observed at 15 min. Finally, a specific ERK1/2 inhibitor, UO126, blocked leptin-induced ERs regulation in ATDC5 cells, indicating that ERK1/2 mediates, partly, the effects of leptin on ERs. These data demonstrate, for the first time, that leptin regulates the expression of ERs in growth plate chondrocytes via ERK signaling pathway, thereby suggesting a crosstalk between leptin and estrogen receptors in the regulation of bone formation.

Gender- and region-specific variations of estrogen receptor α and ß expression in the growth plate of spine and limb during development and adulthood.

Although estrogen action is indispensable for normal bone growth in both genders, the roles of estrogen receptors (ERs) in mediating bone growth are not fully understood. The effects of ER inactivation on bone growth are sex and age dependent, and may differ between the axial and appendicular regions. In this study, the spatial and temporal expression of ERα and ß in the tibial and spinal growth plates of the female and male rats during postnatal development was examined to explore the possible mechanisms. The level of mRNA was examined and compared with quantitative real-time PCR. The spatial location was determined by immunohistochemical analysis. The 1-, 4-, 7-, 12- and 16-week age stages correspond to early life, puberty and early adulthood after puberty, respectively. Gender- and region-specific differences in ERα and ß expression were shown in the growth plates. Mainly nuclear staining of ERα and ß immunoreactivity was demonstrated in the spinal and tibial growth plate chondrocytes for both genders. Moreover, our study indicated significant effect of gender on temporal ERα and ß expression and of region on temporal ERα/ERß expression ratio. However, spatial differences of region-related ERα and ß expression were not observed. Gender-related spatial changes were detected only at 16 weeks of both spine and limb growth plates. ERα and ß immunoreactivity was detected in the resting, proliferative and prehypertrophic chondrocytes in the early life stage and during puberty. After puberty, ERα expression was mainly located in the late proliferative and hypertrophic chondrocytes in female, whereas the expression still extended from the resting to hypertrophic chondrocytes in males. Gender- and region-specific expression patterns of ERα and ß gene might be one possible reason for differences in sex- and region-related body growth phenotypes. Gender, age and region differences should be taken into consideration when the roles of ERs in the growth plate are investigated.

Cage subsidence does not, but cervical lordosis improvement does affect the long-term results of anterior cervical fusion with stand-alone cage for degenerative cervical disc disease: a retrospective study.

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.

Anterior cervical discectomy and fusion versus anterior cervical corpectomy and fusion for multilevel cervical spondylosis: a systematic review.

INTRODUCTION: There is considerable controversy as to which technique is best option for reconstruction after multilevel anterior decompression for cervical spondylosis. The aim of this study was to compare the clinical and radiographic results and complications of anterior cervical discectomy fusion (ACDF) and anterior cervical corpectomy fusion (ACCF) in the treatment of multi-level cervical spondylosis. METHOD: We reviewed and analyzed papers published from Jan 1969 to Dec 2010 regarding the comparison of ACDF and ACCF for multilevel cervical spondylosis. Statistical comparisons were made when appropriate. RESULTS: Twelve studies were included in this systematic review. Blood loss was greater for ACCF compared with ACDF. Similarly, the rate of graft dislodgement in ACCF was higher than that in ACDF. Nonunion rates were 18.4% for 2-level ACDF and 37.3% for 3-level ACDF, whereas nonfusion rates were 5.1% for single-level ACCF and 15.2% for 2-level ACCF. In addition, nonunion rates for three disc levels fused were much higher than that for two disc levels fused, regardless of discectomy or corpectomy. Clinical outcome was compared between ACDF and ACCF in nine studies. Of these, similar outcome was found between ACDF and ACCF in six studies, whereas three studies reported better outcome in ACCF compared with ACDF. CONCLUSION: Nonunion rates of ACDF are higher than those of ACCF for multilevel cervical spondylosis. Sometimes, clinical outcome of ACCF was better than ACDF for multilevel cervical spondylosis.

Reliability of the measurement of thoracolumbar burst fracture kyphosis with Cobb angle, Gardner angle, and sagittal index.

INTRODUCTION: Kyphotic deformity plays a key role in our evaluation of patients with thoracolumbar burst fracture, and there are several variables available for kyphotic deformity assessment, including Cobb angle, Gardner angle, and sagittal index. However, it remains unknown about intra- and inter-observer variability of sagittal index. AIM: The purpose of this study is to determine the reliability of the measurement for thoracolumbar burst fracture kyphosis using Cobb angle, Gardner angle, and sagittal index. Thirty-five patients with thorocolumbar burst fractures treated in our institute were identified. The lateral spine radiographs and midsagittal CT images of the 35 patients were measured on two separate occasions, in random order, by five attending spine surgeons using Cobb angle, Gardner angle, and sagittal index. METHOD: We statistically assessed the agreement, the intra-observer and the inter-observer reliability of the three methods. The intra-observer reliability is always better than the inter-observer reliability, regardless of the parameter being measured or the imaging modality. RESULTS: Intra-class correlation coefficients (ICC) were the most consistent for Cobb angle, followed by Gardner angle and sagittal index. Midsagittal CT images had better intra- and inter-observer reliabilities than lateral plain radiography. Also, agreement was better using midsagittal CT images as compared with lateral plain radiography. CONCLUSION: The results of our study suggest that Cobb angle is the most consistent in terms of intra- and inter-observer reliabilities in the assessment of thoracolumbar burst fracture kyphosis.

Lentiviral shRNA silencing of CHOP inhibits apoptosis induced by cyclic stretch in rat annular cells and attenuates disc degeneration in the rats.

The expression of CHOP (C/EBP homologous protein), an apoptosis regulated gene, increases during endoplasmic reticulum (ER) stress induced by cyclic stretch and leads to rat AF cells apoptosis. However, whether the suppression of CHOP can inhibit apoptosis and attenuates disc degeneration by cyclic stretch remains unclear. The aim of this study was to evaluate the suppressive effects of lentiviral CHOP shRNA on apoptosis induced by cyclic stretch in rat annulus fibrosus (AF) cells in vitro and disc degeneration of rat lumber spine in vivo. Lentiviral CHOP shRNA was constructed and introduced into AF cells. After stretched by the Flexcell Tension Plus system with 20% elongation for 36 h, silencing of the CHOP gene was identified by RT-PCR and Western blot. Inhibition of apoptosis was detected by flow cytometry, and nuclei morphologic changes were visualized by Hoechst 33258 staining. The effect of CHOP shRNA on disc degeneration was determined in vivo by using a rat model. At 7 weeks after intradiscal injection of the control or CHOP shRNA in the L4/L5 and L5/L6 discs, disc degeneration was assessed by X-ray examination, magnetic resonance imaging (MRI) assessment, and HE and TUNEL staining. A significant decrease in CHOP mRNA and protein expression was detected in AF cells with CHOP shRNA transfection after 36 h stretch. There was a significant decrease in apoptotic incidence in cells treated with CHOP shRNA, which was parallel to the expression of CHOP. Injection of CHOP shRNA in vivo resulted in the improvement in MRI and histologic score, and decrease in the apoptosis in the disc. No significant change in disc height was observed. In conclusion, a novel lentiviral vector expressing CHOP shRNA efficiently inhibits apoptosis in rat AF cells by silencing CHOP expression. In a rat model, intradiscal injection of CHOP shRNA induces the suppression of disc degeneration. The therapeutic effects of lentiviral CHOP shRNA should be further explored.

Age-related variations of leptin receptor expression in the growth plate of spine and limb: gender- and region-specific changes.

Leptin is a potent growth-stimulating factor of bone. The effects of leptin on bone growth differ significantly between axial and appendicular regions. Gender differences of leptin function have also been suggested in normal pubertal development. To explore the mechanisms underlying these effects, we investigated the spatial and temporal expressions of the active form of the leptin receptor (Ob-Rb) in the tibial and spinal growth plates of the female and male rats during postnatal development. The 1-, 4-, 7-, 12- and 16-week age stages are representative for early life, puberty and early adulthood after puberty, respectively. Quantitative real-time PCR was used for Ob-Rb mRNA examination and comparison. The spatial location of Ob-Rb was determined by immunohistochemical analysis. There were gender- and region-specific differences in Ob-Rb mRNA expression in the growth plate. Mainly cytoplasm staining of Ob-Rb immunoreactivity was observed in the spinal and tibial growth plate chondrocytes of both genders. Spatial differences of region- and gender-related Ob-Rb expression were not observed. Ob-Rb immunoreactivity was detected in the resting, proliferative and prehypertrophic chondrocytes in early life stage and during puberty. After puberty, staining was mainly located in the late proliferative and hypertrophic chondrocytes. The results of Ob-Rb HSCORE analysis were similar to those obtained from quantitative real-time PCR. Our study indicated direct effects on the chondrocytes of the growth plate in different development stages. The region-specific expression patterns of Ob-Rb gene might be one possible reason for contrasting phenotypes in limb and spine. Different Ob-Rb expression patterns might partly contribute to age- and gender- related differences in trabecular bone mass.

Cervical spondylotic amyotrophy.

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.

Axial pain after posterior cervical spine surgery: a systematic review.

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.

Cyclic stretch-induced apoptosis in rat annulus fibrosus cells is mediated in part by endoplasmic reticulum stress through nitric oxide production.

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.

Degenerative cervical spondylolisthesis: a systematic review.

PURPOSE: Degenerative cervical spondylolisthesis has received insufficient attention, in contrast to degenerative lumbar spondylolisthesis. In fact, degenerative cervical spondylolisthesis may be more common than previously thought. METHODS: In order to provide appropriate guidelines for the treatment of degenerative cervical spondylolisthesis, a systematic review of degenerative cervical spondylolisthesis was performed. An English literature search from January 1947 to November 2010 was completed with reference to radiological examination and management of degenerative cervical spondylolisthesis. RESULTS: Of 102 patients with degenerative cervical spondylolisthesis, 52 patients (51%) had neck or occipital pain, 23 patients (22.5%) were referred with radiculopathy and 65 patients (63.7%) presented with myelopathy or myeloradiculopathy. Degenerative cervical spondylolisthesis was most common in C3/4 and C4/5, occurring in 81 patients at C3/4 (46%) and 87 at C4/5 (49.4%). Disc degeneration and facet hypertrophy were the main causes of this clinical entity. Of 123 patients, 57 (46.3%) were found to have segmental instability as shown by flexion-extension lateral radiographs. There are two classification systems for degenerative cervical spondylolisthesis. Surgery was indicated in patients who had radiologically proven cervical spondylolisthesis with instability and/or spinal cord compression. CONCLUSION: Prospective studies should be designed in the future to draw a more reliable conclusion about the management of degenerative cervical spondylolisthesis.

Extreme lateral lumbar disc herniation in a 12-year child: case report and review of the literature.

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.

Posterior atlantoaxial dislocation without fracture and neurologic deficit: a case report and the review of literature.

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.

Bioabsorbable versus metallic interference screw fixation in anterior cruciate ligament reconstruction: a meta-analysis of randomized controlled trials.

PURPOSE: The aim of the study was to investigate the outcomes between bioabsorbable and metallic screw fixation in anterior cruciate ligament (ACL) reconstruction. METHODS: Randomized controlled trials (RCTs) comparing bioabsorbable versus metallic screw fixation in single-bundle ACL reconstruction were identified systematically, and the outcomes were analyzed in terms of infection rate, knee joint effusion, Lysholm score, International Knee Documentation Committee final score, pivot-shift test, and KT-1000/-2000 arthrometer (MEDmetric, San Diego, CA) measurements. The type of grafts was ignored in the meta-analysis. Standard mean difference (SMD) or risk ratio (RR) with 95% confidence interval (CI) was calculated by a fixed-effects or random-effects model. Heterogeneity across the studies was also assessed. RESULTS: We included 10 studies comprising 790 patients who were treated by bioabsorbable versus metallic screw fixation for single-bundle ACL reconstruction. The meta-analyzed results of these studies showed that there was no statistically significant difference between bioabsorbable and metallic screw fixation in infection rate (RR, 0.91; P = .87; 320 patients in 5 studies), KT-1000/2000 arthrometer testing (SMD, -0.01; P = .95; 438 patients in 7 studies), pivot-shift testing (RR, 1.06; P = .82; 260 patients in 4 studies), International Knee Documentation Committee final score (RR, 0.87; P = .63; 300 patients in 5 studies), and Lysholm score (SMD, 0.03; P = .89; 204 patients in 4 studies). The incidence of knee effusion was higher in the bioabsorbable screw group (RR, 2.57; P = .04; 421 patients in 4 studies). CONCLUSIONS: There was no significant difference in measurement results of knee joint stability or knee joint function outcome between bioabsorbable and metallic interference screws. Knee joint effusion is more common after ACL reconstruction with bioabsorbable interference screw fixation than with metallic interference screw fixation. More high-methodologic quality randomized controlled trials would be helpful in further meta-analysis. LEVEL OF EVIDENCE: Level I, meta-analysis.

Reduction and fixation of the avulsion fracture of the tibial eminence using mini-open technique.

The purpose of this prospective study is to present and evaluate a new technique using suture anchors for the treatment of the avulsion fractures of the tibial eminence. Twenty-three consecutive patients with the displaced avulsion fracture of the tibial attachment of anterior cruciate ligament were treated using mini-open technique with suture anchors between 2005 and 2008. According to the classification of Meyers and McKeever, there were 5 type II, 13 type III, and 5 type IV fractures. The median follow-up period was 18 months (range, 12-32 months). The patient assessment included Lysholm score, Tegner score, IKDC score, and radiographic evaluation. The median Lysholm score improved from 32 (range, 28-48) preoperatively to 98 (range, 85-100) postoperatively. The median preoperative Tegner score was 3 (range, 2-5), and the median postoperative Tegner score was 7 (range, 5-9). The global IKDC objective score was normal (A) in 21 knees and nearly normal (B) in 2 knees. At final follow-up, the Lachman test and anterior drawer test were negative. The results showed that mini-open reduction and fixation of avulsion fracture of the tibial eminence with suture anchors have achieved satisfactory results. We suggest the use of this technique for treating avulsion fractures of the tibial eminence.

Anterior-only instrumentation and grafting after L5 corpectomy for non-traumatic lesions.

Anterior decompression and reconstruction have been used for the treatment of various conditions at the lumbosacral junction, particularly those necessitating corpectomy because of destruction due to primary or secondary bone tumour or infection. The authors conducted a prospective study on 15 consecutive patients who underwent L5 (L4-L5 in 3 cases) corpectomy for tumour or infection, between 2000 and 2005: 6 for tumour, 7 for tuberculous spondylitis, and 2 for pyogenic spondylitis. Corpectomy, bonegrafting (tricortical iliac bone graft or titanium mesh-bone graft) and anterior-only instrumentation (screw-plate or screw-rod) were performed via a retroperitoneal approach. One month of bed rest yielded additional stability. The patients were followed up for an average of 39.7 months (range: 7-73 months). Pain relief and neurological recovery were excellent. Solid fusion was obtained in all patients. There were no cases of plate or screw failure. Three patients with metastases died after 7, 17, and 13 months, in spite of successful fusion. No recurrence was noted in all 9 patients with spinal infection. The results observed indicate that grafting and anterior-only instrumentation and grafting is an effective and safe procedure for reconstruction of the lumbosacral junction following L5 (or even L4-L5) corpectomy; it may obviate the need for additional posterior stabilization in selected patients.