Posterior short-segment fixation in thoracolumbar unstable burst fractures - Transpedicular grafting or six-screw construct?

OBJECTIVES: Early implant failure and donor-site complication remain a concern in patients with thoracolumbar burst fracture underwent one-above and-below short-segment posterior pedicle screw fixation with fusion. Our aim was to evaluate the results of short-segment pedicle instrumentation enforced by two augmenting screws or injectable artificial bone cement in the fractured vertebra, and compare the differences between these two PATIENTS AND METHODS: We conducted a retrospective clinical and radiographic study. Twenty-seven patients were treated with a six-screw construct (group 1), and twenty-nine patients underwenta four-screw construct and fractured vertebra augmentation by injectable calcium sulfate/phosphate cement (group 2). Posterior or posterolateral fusions were not performed in both groups. The severity of the fractured vertebra was evaluated by the load-sharing classification (LSC). Local kyphosis and anterior body height of the fractured vertebra were measured and were follow-up at least 2 years. Any implant failure or loss of correction >10° degrees at the final was defined as failure of surgery. Patients' clinical results were assessed by the Denis scale.

RESULTS: Blood loss and operation time were less in group 1 (126.2±9.7 vs. 267.6±126.1ml, p<0.001 and 141.2±48.7 vs. 189.8±16.4min, p<0.001). Immediately after surgery, group 2 had a better local kyphosis angle (3.7±5.3 vs.6.0±4.1°, p=0.047) and acquired more anterior body height (94.9%±7.6% vs. 84.9%±10.0%, p<0.001). Both groups had similar clinical results (pain score: 1.5±0.8vs. 1.4±0.6, p=0.706; work score: 1.7±0.9 vs. 1.6±1.0, p=0.854). Group 1 had 3 cases of surgery failure; group 2 had 8 cases of implant failure (p=0.121). The average LSC score of these 11 patients with surgical failure was 7.2.

CONCLUSION: Thesix-screw construct had the advantage of shorter operating time, less blood loss, and lower failure rate. For those patients with anLSC score ≧7, posterior short-segment instrumentation should be used cautiously.