Both medial closing wedge and lateral opening wedge distal femoral osteotomy for valgus knee deformity can maintain leg length: A radiographic comparative study.

Purpose: To compare the radiological outcomes of medial closed wedge distal femoral osteotomy (MCWDFO) and lateral open wedge distal femoral osteotomy (LOWDFO), with a focus on evaluating leg length discrepancy (LLD). It was hypothesised that MCWDFO would result in a greater reduction in leg length compared to LOWDFO.

Methods: Patients who underwent MCWDFO or LOWDFO for valgus deformity at a single institution between 2014 and 2022 with a minimum follow-up of 1 year were included. Radiological assessment included hip-knee-ankle (HKA) angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), length of the whole leg and femur and LLD. The difference between pre- and post-operative values for each parameter is expressed as Δ. The radiological outcomes were statistically evaluated for each procedure.

Results: Fifty-two patients (26 MCWDFO and 26 LOWDFO) were included. No significant differences were observed between the two groups with respect to demographic data and radiological parameters such as HKA, mLDFA and MPTA. Although Δ length of the femur decreased post-MCWDFO (-2.7 ± 0.6 mm) and increased post-LOWDFO (+2.7 ± 0.4 mm), the Δ length of the whole leg post-MCWDFO decreased (-0.5 ± 3.8 mm) and increased post-LOWDFO (+1.7 ± 2.6 mm) ( < 0.001). The straight-lengthening effect on the length of whole leg was significantly greater in MCWDFO than in LOWDFO (+2.0 ± 4.1 mm vs. -1.1 ± 2.5 mm,  > 0.001).

Conclusions: The straight-lengthening effect of alignment correction minimises changes in overall leg length, regardless of the specific DFO technique.

Level Of Evidence: Level III, retrospective comparative study.