Lateral closing wedge high tibial osteotomy procedure for the treatment of medial knee osteoarthritis: eleven years mean follow up analysis.

Purpose: To assess long term survivorship, patient reported (PROMs) and radiological outcomes, and rate of adverse events and hardware removal after lateral closing wedge high tibial osteotomy (CWHTO) for the treatment of medial knee osteoarthritis (OA) and varus malalignment.

Methods: Retrospective analysis of patients who underwent isolated CWHTO for medial OA in varus knee between 2009 and 2019 at the same institution was performed. Surgical failure was defined as conversion to total knee arthroplasty (TKA) or need for osteotomy revision procedure for varus recurrence, while clinical failure was defined by a Lysholm score under 65 points. Lysholm score, Visual Analogue Scale for pain (VAS), and patients' satisfaction with the treatment were evaluated. Radiographic parameters assessed included OA degree with the Kellgren Lawrence scale (KL), hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), joint line convergence angle (JLCA), and posterior tibial slope (PTS). Adverse events and rate of hardware removal procedures were recorded through follow up visits and clinical records. Survival analysis was conducted through Kaplan-Meier method with surgical and clinical failure as endpoints.

Results: 70 knees (mean age at surgery 43.3 years) were included in the survivorship analysis at a mean follow up of 11.6 ± 3.4 years. A failure rate of 12.85% (9/70) was recorded during the follow up period, with a survivorship of 92% and 75% at ten and 15 years of follow up, respectively. Mean Lysholm score and VAS at follow up were above the PASS threshold reported in literature. The 75.7% of patients were satisfied with the treatment. Radiological follow up indicated a residual mechanical varus of 2.1°, a decrease of 0.7° of intra articular deformity (JLCA), no change in PTS nor in KL index. The adverse events rate recorded was 5.7% (4/70). In nine knees (14.7%) among the patients survived from surgical failure a subsequent hardware removal procedure was performed.

Conclusion: CWHTO represents a safe procedure, which resulted in high survivorship (92% and 75% at ten and 15 years follow up, respectively), with satisfactory PROMs and radiological outcomes at long term follow up in patients affected by medial OA and varus malalignment.

Level of evidence: 5, Case Series.