Kyphotic Angle Progression of Thoracic and Thoracolumbar Tuberculous Spondylitis after Surgical Treatment: Comparison with Predicted Kyphosis Outcome after Conservative Treatment

STUDY DESIGN Retrospective comparative study. PURPOSE To compare the progression of the kyphotic angle (KA) in a surgically treated group with the predicted outcome of a conservatively treated group. OVERVIEW OF LITERATURE Late onset kyphosis is a complication of tuberculous spondylitis making its prevention a major goal of surgery. METHODS Twenty six consecutive patients underwent an anterior reconstruction and posterior instrumented fusion in conjunction with antituberculous chemotherapy. The mean follow up was 56 months (range, 28 to 112 months). The patients were divided into subgroups based on the involved region of the thoracic and the thoracolumbar spine, initial KA, and the initial vertebral body loss (VBL(x)). The predicted KA (KA(Pd)) was calculated using the formula, KA(Pd)=5.5+30.5 VBL(x), to predict the final gibbus deformity. Kyphotic angle progression (DeltaKA) based on the radiographic measurements after surgery (DeltaKA(R)), and the predicted outcome of conservative treatment (DeltaKA(P)) with chemotherapy were compared. RESULTS Among the subgroups of the regions involved and initial KA, the DeltaKA was radiographically superior with a reduced amount of kyphogenesis in the surgery group than the predicted outcome of the conservatively treated patients (p<0.05). The radiographic DeltaKA was similar (p>0.05) with VBL(x)</=0.5 in the VBL(x) subgroup. CONCLUSIONS These results showed that in the VBL(x) subgroup, an initial VBL(x)</=0.5 is an indication of conservative antituberculous chemotherapy without surgery.