Summary

double-level vs. single-level derotational osteotomy

Abstract

Purpose

to investigate whether double-level (femur + tibia) derotational osteotomy is superior to single-level femoral derotational osteotomy for recurrent patellar dislocation with severe femoral and tibial rotational deformities (femoral anteversion >30° and external tibial torsion >30°).

Methods

Between January 2015 and June 2020, a total of 115 knees with recurrent patellar dislocation treated with combined medial patellofemoral ligament reconstruction (MPFL-R) and derotational osteotomies were evaluated after a minimum follow-up of 2 years. Among these cases, 15 knees who underwent double-level derotational osteotomy were included in the double-level group, which was propensity-matched in a 1:2 ratio to a single-level group of patients who underwent single-level femoral derotational osteotomy (30 knees). The clinical and radiological outcomes were evaluated and compared between the groups. Furthermore, the foot progression angle was measured preoperatively and 2 years after surgery.

Results

The patient-specific variables did not differ significantly between the double-level group and the single-level group after propensity score matching. The postoperative mean foot progression angle was significantly lower in the double-level group than in the single-level group (9° ± 8 vs. 15° ± 11, P=0.014 ), however, there were no statistically significant differences between the groups in terms of any other clinical and radiological assessments.

Conclusion

For patients with severe femoral and tibial torsional deformities (femoral anteversion >30° and external tibial torsion >30°), double-level derotational osteotomy is superior to single-level osteotomy in maintaining normal foot progression angle, but it does not show an advantage in terms of patient-reported outcomes, radiological results, and redislocation rate at minimum 2 years of follow-up. Furthermore, concomitant excessive external tibial torsion (>30°) did not have an adverse effect on clinical outcomes in patients who underwent derotational distal femoral osteotomy with MPFL-R due to excessive femoral anteversion.