Summary

The effect of performing an isolated lateral closing wedge distal femoral osteotomy is comparable to performing medial open wedge high tibial osteotomy in the physiological correction of varus malalignment.

Abstract

Background

While a medial open wedge high tibial osteotomy (mowHTO) has demonstrated clinical efficacy in the correction of tibial based varus malalignment, a mounting body of evidence questions its role in the correction of femoral based varus malalignment, due to the creation of a non-physiological, oblique knee joint line (KJL). However, the clinical effectiveness of alternatively performing an isolated lateral closing wedge distal femoral osteotomy (lcwDFO) in femoral based varus malalignment, that only leads to biomechanical unloading near full knee extension with limited effects during knee flexion, is yet to be confirmed.
Purpose/Hypothesis
The aim was to compare clinical outcomes between patients undergoing varus correction via isolated lcwDFO or mowHTO, performed according to the location of the deformity, in a cohort matched for confounding variables. It was hypothesized that undergoing isolated lcwDFO for symptomatic varus malalignment would not significantly differ from the results after mowHTO.

Methods

Between 01/2010-10/2019, consecutive patients who underwent isolated mowHTO or lcwDFO according to a tibial- or femoral-based symptomatic varus deformity were enrolled in this retrospective cohort study of prospectively collected outcome data. Confounding factors including age at surgery, sex, body mass index, preoperative femorotibial axis, and postoperative follow-up were matched utilizing propensity score matching. The International Knee Documentation Committee (IKDC) Subjective Knee Form, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm Score, Tegner Activity Scale, and visual analogue scale (VAS) for pain were collected preoperatively and at a minimum of 24 months postoperatively.

Results

Using propensity score matching, out of 535 cases assessed for eligibility, 50 patients (n=25 per group) were selected. Postoperatively, both the the lcwDFO group (IKDC: 49.4±14.6 vs. 66±20.1, p=.003; WOMAC: 25.2±17.0 vs 12.9±17.6, p=.003; Lysholm: 46.5±15.6 vs 65.4±28.7, p=.011; VAS: 4.5±2.2 vs 2.6±2.5, p=.001) as well as the mowHTO group (IKDC: 55.1±16.5 vs. 71.3±14.7, p<.001; WOMAC: 22.0±18.0 vs 9.6±10.8, p<.001; Lysholm: 55.2±23.1 vs. 80.7±16, p<.001; VAS: 4.1±2.4 vs 1.6±1.8, p<.001) had significantly improved at follow-up (80±20 vs. 81±43months) compared to preoperatively. There were no significant differences between the groups, neither at baseline nor at final follow-up nor regarding the amount of clinical improvement in any of the outcome parameters (p>.05; respectively).

Conclusion

If performed according to the location of the deformity in an effort to sustain a physiological joint line, performing both mowHTO or lcwDFO yields significant improvement in postoperative clinical outcomes in the correction of varus malalignment. In an effort to confirm the clinical effectiveness of this novel procedure, the results of this study serve an evidence-based rationale to recommend an isolated lcwDFO in femoral based varus malalignment, which is comparable to that of a mowHTO in the physiological correction of varus malalignment.