Increased joint obliquity after open-wedge high tibial osteotomy induces pain in the lateral compartment: a comparative analysis of the minimum 4-year follow-up outcomes using propensity score matching.

PURPOSE

To analyze the effects of increased medial proximal tibial angle (MPTA) on the clinical outcomes and cartilage deterioration in the lateral compartment after a mean follow-up period of 4 years following open-wedge high tibial osteotomy (OWHTO) using propensity score matching (PSM) analysis.

METHODS

Among 376 knees treated with OWHTO for medial unicompartmental osteoarthritis with varus deformity, 36 knees with MPTA increase of > 95° and 108 knees with MPTA increase of < 95° at the final follow-up were included. The baseline prognostic factors [age, sex, preoperative hip-knee-ankle (HKA) angle, body mass index, and preoperative knee range of motion] were equalized between the 2 groups using PSM; consequently, 31 pairs of patients were compared. The radiographic and clinical outcomes, including lateral compartment pain, were assessed. For 18 patients in each group, second-look arthroscopy and cartilage status assessment were performed.

RESULTS

The preoperative demographics were similar between the groups. At the final follow-up, the HKA angle and joint line obliquity were significantly higher in the increased MPTA group. No significant differences were observed in the clinical outcomes between the groups. On second-look arthroscopy, significant cartilage deterioration of the lateral compartment was not observed in either group. Pain in the lateral compartment was experienced significantly more frequently in the increased MPTA group (p < 0.01).

CONCLUSION

Although excessively increased MPTA after HTO had no significant effects on the clinical outcomes and cartilage deterioration in the lateral compartment at the minimum 4-year follow-up, lateral compartment pain was experienced significantly more frequently in the increased MPTA group.