Correction of distal femoral valgus deformities with fixator-assisted plating: How accurate is the correction?

Objective: The aim of this study was to evaluate the results of fixator assisted correction of the distal femoral valgus deformities and the precision of the correction. Methods: Seventeen extremities of 13 patients (7 women and 6 men; mean age: 16 ± 5.4 years) who had fixator assisted plating of the distal femur for genu valgum deformity were evaluated. Mechanical axis deviation (MAD) and mechanical lateral distal femoral angles (mLDFA) were measured pre-operatively and post-operatively. mLDFA was graded as perfect if it is between 85 and 90(85 x 90); overcorrection if it is between 91 and 95 (91 x 95) and undercorrection if it is between 80 and 85 (80 x < 85). Measurements beyond those limits were graded as a poor result. The position of the mechanical axis line with respect to center of the knee was graded from zone 1 to zone 4 pre-operatively and post-operatively. Results: The mean follow-up period was 12.8 ± 3.7 months. The pre-operative and post-operative mLDFA was 70.5±9.4 (range, 57e82) and 87.7 ± 3.5 (range, 80e94), respectively (p < 0.001). Based on post-operative standing radiographs, the correction was graded perfect in 12 femurs. The correction in three femurs were graded as overcorrection and graded as undercorrection in two femurs. Sagittal plane correction was also achieved in two femurs. Peroneal nerve decompression was done in three patients (5 extremities) with valgus deformity over 30. The mechanical axes in all lower extremities were passing through zone 2 or more, pre-operatively, whereas the mechanical axes were in zone 2 or more in five extremities post-operatively. Conclusion: Fixator assisted plating is an effective treatment modality in patients with distal femoral valgus deformity. Although the technique enables to obtain significant correction in coronal plane it has the disadvantages of over- and undercorrection. Thus, we advise intraoperative confirmation of the correction under fluoroscopic control.

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