Summary

Proximal tibial osteotomy（PTO） with arthroscopic centralization technique decreased medial meniscus extrusion, but no difference in clinical outcomes were founded compared to PTO alone over a two-year period postoperatively.

Abstract

【Purpose/Hypothesis】 This study aimed to compare the radiologic and clinical outcomes of the Proximal tibial osteotomy (PTO) combined with arthroscopic centralization technique versus PTO alone in patients with medial knee osteoarthritis after adjusting for confounding factors. We hypothesized that the addition of the centralization technique would improve outcomes by reducing medial meniscus extrusion and enhancing overall clinical and radiologic results.【Methods】A total of 32 knees (32 patients) that underwent medial open-wedge PTO with the centralization technique (P+C group) at our department and affiliated hospitals between April 2020 and March 2022 were retrospectively included, with a follow-up of at least two years. The comparison group consisted of 92 knees (84 patients) that underwent PTO alone at our department since 2013. Propensity score matching at a 1:1 ratio was performed to adjust for age, sex, BMI, preoperative Kellgren-Lawrence (KL) grade, preoperative % mechanical axis (MA), and preoperative medial meniscus extrusion (MME).The target alignment was set at %MA of 58-60% in the P+C group and 62.5% in the P group. Radiographic parameters (hip-knee-ankle angle [HKA], mechanical lateral distal femoral angle, mechanical medial proximal tibial angle [mMPTA], joint line convergent angle, knee joint line obliquity [KJLO], and lateral distal tibial angle [LDTA]), arthroscopic findings of ICRS cartilage evaluation, and clinical outcomes (Knee injury and Osteoarthritis Outcome measures[KOOS]) were compared preoperatively and at the final follow-up. In addition, MME was assessed in the P+C group preoperatively and at the final follow-up. Statistical analyses were performed using the t-test, paired t-test, and Fisher's exact test.【Results】 After propensity score matching, 20 knees from each group were compared. The mean age at surgery in the P+C group was 63.9 ± 7.9 years, and the mean follow-up period was 2.5 ± 0.3 years. At the final evaluation, significant differences were observed between the groups in HKA, mMPTA, KJLO, and LDTA (P+C group vs. P group, mean ± SD, degrees: HKA; 3.3 ± 2.2 vs. 0.8 ± 2.6, p = 0.00243, mMPTA; 92.3 ± 1.8 vs. 90.0 ± 2.2, p = 0.00124, KJLO; 1.6 ± 1.5 vs. 0.0 ± 1.9, p = 0.008, LDTA; 94.0 ± 3.7 vs. 91.2 ± 4.5, p = 0.0397). Although both groups showed significant improvement in KOOS scores, there were no significant differences in KOOS scores or arthroscopic findings between the groups. The MME in the P+C group significantly decreased from 4.3 ± 1.4 mm preoperatively to 3.4 ± 1.3 mm at the final follow-up (p = 0.0106).【Discussion】 The combination of PTO with the arthroscopic centralization technique reduced MME; however, no difference in clinical outcomes were found over a two-year period postoperatively, and comparable clinical outcomes were achieved with under-correction compared to conventional target alignment. Limitations included the small sample size and short follow-up duration, which necessitated further long-term follow-up.【Conclusion】 Although no short-term differences in clinical outcomes were observed when PTO was combined with the arthroscopic centralization technique, MME decreased, suggesting potential effectiveness in long-term outcomes.