Anterior-only stabilization using plating with bone structural autograft versus titanium mesh cages for two- or three-column thoracolumbar burst fractures: a prospective randomized study.

Department of Orthopedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Spine (Impact Factor: 2.16). 07/2009; 34(14):1429-35. DOI: 10.1097/BRS.0b013e3181a4e667
Source: PubMed

ABSTRACT A randomized, controlled follow-up study to review patients with acute thoracolumbar burst fractures treated by anterior instrumentation and reconstruction.
The objective of this study was to evaluate the results of anterior instrumentation in the treatment of thoracolumbar burst fractures and to determine whether anterior-only approach would be sufficient for highly unstable burst fractures. In this prospective follow-up study, we also compared the results of anterior reconstruction with structural grafting and with titanium mesh cage in a randomized fashion.
Anterior decompression and reconstruction supplemented with instrumentation is generally believed to be superior to fixation with posterior pedicle screw instrumentation for a highly unstable burst fracture, but the indications and methods for anterior approach has not been fully documented.
A total of 65 patients undergoing anterior plating for a thoracolumbar burst fracture with a load-sharing score of 7 or more between 2000 and 2003 were included this study. They were randomized to receive iliac crest autograft (group A, n = 32) or titanium mesh cages (group B, n = 33). The patients were similar in the distribution of 3-column injuries (n = 8 in group A vs. n = 9 in group B). During the minimum 4-year (range, 4-7 years) follow-up period, all patients were prospectively evaluated for clinical and radiologic outcomes. The Frankel scale, the ASIA motor score, and the Short Form 36 were used for clinical evaluation, whereas the fusion status and the loss of kyphosis correction for the local kyphosis angle were examined for radiologic outcome.
All patients in this study achieved solid fusion, with significant neurologic improvement and no significant correction loss as defined by loss of kyphosis correction. The clinical and radiologic results were not significantly different (P > 0.05) at all time points between the 2 groups A and B. Twenty-six of 32 patients in group A still complained of donor site pain to some degree at the final follow-up. No significant impact of 3-column injuries (P > 0.05) were identified on the results for all comparisons.
Anterior-only instrumentation and reconstruction with structural autograft or titanium mesh cages is sufficient for surgical treatment of thoracolumbar burst fractures with a load-sharing score of > or = 7 and even with 3-column injuries.

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    ABSTRACT: Object Despite promising early clinical results, the long-term outcome of the use of expandable titanium cages to reconstruct the anterior column after traumatic burst fractures is still unknown. The purpose of this prospective study was to assess the clinical and radiological outcomes of the use of expandable titanium cages 5 years postoperatively. Methods Eighty patients with traumatic thoracolumbar burst fractures (T4-L5) underwent posterior stabilization followed by anterior corpectomy and reconstruction using expandable titanium cages with or without additional anterior plating. After 5 years, fusion was evaluated by means of plain radiographs and CT scans, and the patients' scores on the Oswestry Disability Index (ODI), their neurological status, and clinical results were assessed. Results Forty-five (56%) of the 80 patients could be examined after 5 years. There was a relatively high rate of complications related to thoracotomy (26%), but there were no complications directly related to the cages. Revision surgery was required in 1 case. The average postoperative loss of correction was only 2.4° due to minimal subsidence of the cages. No cage showed a radiolucent line or instability in flexion-extension views. Bony fusion, as assessed by CT scan, was achieved in 41 patients (91%). On clinical examination, 96% of all patients were ambulatory and showed minimal restriction of spinal range of motion; 71% did not need analgesic medication at all; and 67% were able to work. The average ODI score was 12. Thirty-one percent of patients complained of some kind of anterior approach-related complications. Conclusions Combined anteroposterior stabilization of thoracolumbar burst fractures with expandable titanium cages is a relative safe procedure with satisfactory radiological and clinical long-term outcome. High fusion rates can be achieved, with only minor loss of correction, typically occurring in the 1st year. However, open thoracotomy carries the risks of additional complications and development of post-thoracotomy syndrome.
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    ABSTRACT: Study Design. Biomechanical in vitro laboratory study.Objective. To compare the biomechanical performance of 3 fixation concepts used for anterior instrumented scoliosis correction and fusion (AISF).Summary of Background Data. AISF is an ideal estimate for selective fusion in adolescent idiopathic scoliosis (AIS). Correction is mediated using rods and screws anchored in the vertebral bodies. Application of large correction forces can promote early weakening of the implant-vertebra interfaces with potential postoperative loss of correction, implant dislodgment and non-union. Therefore, improvement of screw-rod anchorage characteristics with AISF is valuable.Methods. 111 thoracolumbar vertebrae harvested from seven human spines completed a testing protocol. Age of specimens was 62.9±8.2 years. Vertebrae were potted in PMMA and instrumented using 3 different devices with identical screw length and unicortical fixation: single constrained screw fixation (SC-fixation), non-constrained dual screw fixation (DNS-fixation) and constrained dual screw-fixation (DC-fixation) resembling a novel implant type. Mechanical testing of each implant-vertebra unit (IVU) using cyclic loading and pullout tests were performed after stress tests were applied mimicking surgical maneuvers during AISF. Test order was as follows: 1) Preload-Test-1 simulating screw-rod locking and cantilever forces; 2) Preload-Test-2 simulating compression/distraction maneuver; 3) Cyclic loading tests with IVU subjected to stepwise increased cyclic loading (max.:200N) protocol with 1000 cycles at 2Hz, tests were aborted if displacement >2mm occurred before reaching 1000 cycles; 4) Coaxial pullout tests at a pullout rate of 5mm/min. With each test the mode of failure, i.e. shear versus fracture, was noted as well as the ultimate load to failure (N), number of IVUs surpassing 1000 cycles, number of cycles and related loads applied.Results. 33% of vertebrae surpassed 1000 cycles, 38% in the SC-group, 19% in the DNS-group and 43% in the DC-group. The difference between the DC-group and DNS-group yielded significance (p = .04). For vertebrae not surpassing 1000 cycles, the number of cycles at implant displacement >2mm in the SC-group was 648.7±280.2 cycles, in the DNS-group 478.8±219.0 cycles, and in the DC-group 699.5±150.6 cycles. Differences between the SC-group and DNS-group were significant (p = .008), as between the DC-group and DNS-group (p = .0009). Load to failure in the SC-group was 444.3±302N, in the DNS-group 527.7±273N and in the DC-group 664.4±371.5N. The DC-group outperformed the other constructs. The difference between the SC-group and DNS-group failed significance (p = 0.25), while there was a significant difference between the SC-group and DC-group (p = .003). The DC-group showed a strong trend towards increased load to failure compared to the DNS-group but without significance (p = .067). Surpassing 1000 cycles had a significant impact on the maximum load to failure in the SC-group (p = 0.0001), the DNS-group (p = .01), but not in the DC-group (p = .2), which had the highest number of vertebrae surpassing 1000 cycles.Conclusion. Constrained dual-screw fixation characteristics in modern AISF implants can improve resistance to cyclic loading and pullout forces. DC-constructs bear the potential to reduce the mechanical shortcomings of AISF.
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