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.

The use of beta-TCP in the surgical treatment of tibial plateau fractures.

The objective of this study was to evaluate the outcome of using beta-TCP in the treatment of depression tibial plateau fractures. A total of 124 patients with depression tibial fractures were included in this study and followed for a minimum of 12 months. All the cases were treated with open reduction and internal fixation, and grafted with beta-TCP ceramic. The clinical and radiological outcomes were assessed using Hospital for Special Surgery (HSS) score of knee and Rasmussen score during the follow-up. No obvious redisplacement was found at the follow-up assessment. Most of the patients had excellent HSS score and Rasmussen clinical score. Bone healing was noted in all fractures and Schatzker II-type fractures had the best functional outcome. The results suggested that using beta-TCP combined with open reduction and rigid internal fixation was an effective treatment for depression fractures of the tibial plateau.

Surgical treatment of calcaneal fractures with use of beta-tricalcium phosphate ceramic grafting.

BACKGROUND: The treatment of calcaneal fractures is challenging. Internal fixation and grafting with sintered beta-tricalcium phosphate (beta-TCP) ceramic is alternative to bone grafting in the treatment of calcaneal fractures. METHODS: Seventy-four patients with intraarticular calcaneal fractures were treated with open reduction, internal fixation and grafting with sintered beta-TCP ceramic. Followup was performed using the Maryland foot score as well as plain radiography. RESULTS: All patients were followed for 15 (range, 12 to 26) months. Clinical results as assessed by the Maryland foot score were excellent in 40 of 74 cases (54.1%), good in 28 (37.8%), and fair in 6 (8.1%). Immediately after surgery, the mean Böhler angle was improved by 23 degrees, and 1 year after surgery, the mean Böhler angle decreased by 4 degrees. A similar change was also seen in Gissane angles and the height and width of the calcaneus. There was no statistical correlation between the severity of fracture and functional outcome in this series. All fractures healed. CONCLUSION: These findings suggest that use of beta-TCP combined with open reduction and internal fixation is an effective and safe method for the surgical treatment of intra-articular calcaneal fractures.

Substrate stiffness regulates apoptosis and the mRNA expression of extracellular matrix regulatory genes in the rat annular cells.

Cells are subjected to static tension of different magnitudes when cultured on substrates with different stiffnesses. It has long been recognized that mechanical stress is an important modulator of the intervertebral disc degeneration. Here we studied the influence of substrate stiffness on cell morphology, apoptosis and extracellular matrix (ECM) metabolism of the rat annulus fibrosus (AF) cells which are known to be mechanosensitive cells. Polyacrylamide gel substrates with three different stiffnesses were prepared by varying the concentration of acrylamide and bisacrylamide, and the elastic modulus of the different gel substrates were measured with atomic force microscopy (AFM). First-passage rat annular cells were cultured on soft, intermediate, rigid substrates or plastics for 24 or 48 h. The percentages of apoptotic cells were detected by flow cytometry and caspase-3 activity, and morphologic changes were visualized by Hoechst 33258 staining and F-actin staining. In addition, the expression of ECM genes (Col1α1, Col2α1, aggrecan, MMP-3, MMP-13 and ADAMTS-5) were analyzed by RT-PCR. The three different substrates had elastic moduli varying between 1±0.23 kPa (soft, 5% gel with 0.06% bis), 32±2.89 kPa (intermediate, 10% gel with 0.13% bis) and 63±3.45 kPa (rigid, 10% gel with 0.26% bis) with a thickness about 60-70 µm. Most of the rat AF cells appeared small and rounded, and lost most of their stress fibers when cultured on soft substrate. There was a significant increase in the percentage of apoptotic cells in the rat AF cells cultured on soft and intermediate substrates relative to those on plastic surface, with a parallel decrease in the area of cell spreading and nucleus. The AF cells grown on intermediate or rigid substrate had reduced expression of Col1α1, Col2α1 and aggrecan and enhanced expression of MMP-3, MMP-13, and ADAMTS-5 at 24h or 48 h, respectively, relative to those cultured on plastic surface. Conversely, we observed an up-regulation of Col2α1 and aggrecan and no change in the gene expression of MMP-3, MMP-13, and ADAMTS-5 in AF cells on soft substrates. Rat AF cells are sensitive to substrate stiffness which can regulate the morphology, growth, apoptosis and ECM metabolism of rat AF cells, thus indicating the importance of substrate choice for cell transplantation and regeneration for the treatment of disc degeneration using tissue-engineering technique.

Single-level instrumented posterolateral fusion of lumbar spine with beta-tricalcium phosphate versus autograft: a prospective, randomized study with 3-year follow-up.

STUDY DESIGN: A prospective, randomized clinical study comparing beta-tricalcium phosphate (beta-TCP) with autograft bone graft with follow-up of 3 years. OBJECTIVE: To determine the efficacy of beta-TCP as a bone graft substitute combined with local autograft obtained from decompression compared with the use of autologous iliac crest bone graft in single-level instrumented posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: A variety of bone graft substitutes have been used in posterolateral lumbar fusion with different efficacy reported, but no controlled study was conducted on the clinical performance of beta-TCP in instrumented posterolateral lumbar fusion. METHODS: Sixty-two patients with symptomatic degenerative lumbar spinal stenosis were treated with single-level instrumented posterolateral lumbar fusion. They were randomly assigned to fusion with beta-TCP combined with local bone obtained from the decompression (group A, n = 32) or autogenous iliac crest bone graft plus decompression bone (group B, n = 30). The patients were observed up for 3 years after surgery. The results were assessed clinically and radiographically. RESULTS: There were no significant differences in recovery rate of Japanese Orthopedic Association score and SF-36 score at all time intervals. Successful radiographic fusion was documented in all patients in both treatment groups. All patients in group B, however, complained bone graft donor site pain although significant improvement of pain was observed during the follow-up. CONCLUSION: Instrumented posterolateral fusion with beta-TCP combined with local autograft results in the same radiographic fusion rates and similar improvement of clinical outcomes and life quality compared with autograft alone. The authors therefore recommend the use of beta-TCP as bone graft substitute for instrumented posterolateral fusion of lumbar spine to eliminate the need of bone grafting harvesting from the ilium.

Management of odontoid fractures with percutaneous anterior odontoid screw fixation.

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.