Accuracy of complex lower-limb deformity correction with external fixation: a comparison of the Taylor Spatial Frame with the Ilizarov ring fixator.

Purpose: Circular external fixators have several advantages over other surgical options in the treatment of limb length discrepancy and axial deformity. The innovative Taylor Spatial Frame (TSF) combines a rigid hexapod fixation system with the support of a web-based software program, and thus offers the possibility of simultaneous corrections of multidirectional deformities. Whilst there is still some scepticism of many Ilizarov device users about the advantages of the TSF, the purpose of the study was to perform a comparison between the TSF and the Ilizarov ring fixator (IRF) with regard to the accuracy of deformity correction in the lower limb.

Methods: Two hundred and eight consecutive deformity corrections in 155 patients were retrospectively evaluated. There were 79 cases treated with the IRF and 129 cases treated with the TSF. The mean age of the patients at the time of surgery was 13.2 years (range; 2-49 years). Standing anteroposterior and lateral radiographs were evaluated preoperatively and immediately after removal of the frames. The final result was compared to the preoperatively defined aim of the deformity correction. According to the treated count of dimensions, we differentiated four types of deformity corrections. The results were graded into four groups based on the persisting axial deviation after removal of the frame.

Results: The aim of the deformity correction was achieved in a total of 90.7% in the TSF group, compared to 55.7% in the IRF group. On the basis of the count of dimensions, the TSF achieved obviously higher percentages of excellent results (one dimension: TSF 100%; IRF 79.3%; two dimensions: TSF 91.8%; IRF 48.6%; three dimensions: TSF 91.1%; IRF 28.6%; four dimensions: TSF 66.7%; IRF 0%). In addition, the degree of the persisting deformity increased with the number of planes of the deformity correction.

Conclusions: The TSF allowed for much higher precision in deformity correction compared to the IRF. In two-, three- and four-dimensional deformity corrections in particular, the TSF showed clear advantages. This may derive from the TSF-specific combination of a hexapod fixator with the support of an Internet-based software program, enabling precise simultaneous multiplanar deformity corrections.