The influence in clinical results of lower limb length discrepancy following distal femoral osteotomy.

Abstract

Background: Distal femoral osteotomy (DFO) improves valgus limb alignment. However, it might affect lower limb length discrepancy (LLD) and influence functional scores. This study aims to evaluate functional scores and radiographic parameters associated with LLD after DFO.

Hypothesis: It was hypothesized that the presence of LLD after DFO affects functional scores and associated with femoral length.

Patients and methods: A total of 50 patients who underwent DFO, including 24 closed wedge (CW) DFO and 26 open wedge (OW) DFO, were included. Patients were divided into three groups according to the presence of LLD after DFO: LLD-Absent group, LLD-CW group and LLD-OW group. Patient demographics, functional scores (Knee injury and Osteoarthritis Outcome Score (KOOS)), and radiographic parameters were evaluated and compared between the three groups. Multivariable logistic regression analysis was used to assess the radiographic parameter associated with the presence of post-operative LLD.

Results: There were no significant differences between the three groups in demographic data, correction angles, complications including hinge fractures, time to osteotomy union, and functional scores. However, the return to sports (RTS) was significantly different between three groups. By further analysis between CWDFO and OWDFO, RTS in CWDFO was faster than those in OWDFO. There were significant differences in post-operative mLDFA and Δ femur length. Additionally, post-operative mLDFA was significantly associated with the presence of LLD (Odds ratio 0.11, 95% confidence interval 0.01 to 0.49, p = 0.03).

Conclusion: Functional scores and postoperative outcomes following DFO are not affected by the presence of LLD. RTS is independent of LLD, but rather dependent on the surgical procedure and RTS in CWDFO was faster than those in OWDFO. Postoperative mLDFA is the radiographic parameter associated with the presence of LLD. These findings are clinically relevant and should be accounted for in preoperative planning of DFO.

Level of evidence iii: Retrospective with comparative study.