Summary
Distal femoral varus deformity is associated with loss of correction and OA progression after OWHTO and related to poor long-term clinical outcomes.
Abstract
Objectives
Osteotomy should be performed at the location of the deformity [1]. Although most of medial knee osteoarthritis (OA) patients have the tibial based deformity, some have distal femoral varus deformity [2]. The purpose of this study is to evaluate the effect of distal femoral morphology on the long-term clinical outcomes in open wedge high tibial osteotomy (OWHTO).
Methods
We retrospectively reviewed 95 knees that underwent OWHTO and at least seven years of follow-up. The mean follow-up period was 10.8 ± 2.6 years (range: 7.6–17.3 years). Clinical parameters, including Japanese Orthopedic Association (JOA) score, Oxford knee score (OKS), and Knee Injury and Osteoarthritis Outcome Score (KOOS) were evaluated. Radiographic evaluations included weight bearing line ratio (WBLR), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and progression of medical OA. The patients were retrospectively divided into two groups according to preoperative LDFA; group N (LDFA <90°) and group O (LDFA ≥ 90°). The groups were compared with respect to the clinical and radiological outcomes after OWHTO.
Results
The mean JOA score significantly improved (from 64.4 ± 11.6 to 90.9 ± 9.3, P < 0.001), and the mean OKS at final follow-up was 40.4 ± 8.3. Six cases were converted to total knee arthroplasty, and the survival rate was 93.7% at 10.8 years of follow-up. Group N (LDFA <90°) had 73 knees and group O (LDFA ≥ 90°) had 22 knees. Group O had significant inferior clinical outcomes at last follow up in all clinical scores. Radiologically, significant loss of correction and medial OA progression were observed in group O.
Conclusions
Distal femoral varus deformity is associated with loss of correction and OA progression after OWHTO and related to poor long-term clinical outcomes. Distal femoral osteotomy should be considered for varus alignment of the knee with larger LDFA.
References
[1] Paley D et al. Principles of deformity correction around the knee. Orthopade. 2000
[2] Abe K et al. Constitutional varus knee due to tibial deformity is common and represents a good indication for high tibial osteotomy in Japanese population: Consideration of 1010 knees. Knee Surg Sports Traumatol Arthrosc. 2024