Association Between Joint Line Convergence Angle and Patient-Reported Outcomes of Opening-Wedge High Tibial Osteotomy.

BACKGROUND

A larger joint line convergence angle (JLCA) increases the stress load on the medial compartment. Few reports, however, have discussed the effect of the JLCA on the cartilage status and clinical outcomes after opening-wedge high tibial osteotomy (OWHTO).

PURPOSE/HYPOTHESIS: To reveal the effect of the JLCA on clinical results after OWHTO. We hypothesized that a smaller JLCA improves cartilage status and clinical outcomes by reducing mechanical stress in the medial compartment.

STUDY DESIGN

Cohort study: Level of evidence, 3.

METHODS

This retrospective study included 106 knees that underwent OWHTO and second-look arthroscopy during implant removal 1 year after OWHTO. The mean follow-up period was 5.5 (SD, 2.9) years. The pre- and postoperative JLCAs were measured radiographically. The International Cartilage Repair Society (ICRS) grades of the medial femoral condyle (MFC) and the medial tibial plateau (MTP) were evaluated during the initial and second-look arthroscopy. The relationship between the JLCA and cartilage status, and the Knee injury and Osteoarthritis Outcome Score (KOOS) at the final follow-up were evaluated.

RESULTS

Preoperative JLCA was related to improvements in the ICRS grade of the MFC and the MTP, with cutoff values of 2.6° (sensitivity, 0.700; specificity, 0.561; = .016) and 2.4° (sensitivity, 0.704; specificity, 0.595; = .028), respectively. In addition, the preoperative JLCA was related to KOOS Pain ( = .037), Symptoms ( < .001), Activities of Daily Living ( = .005), Sports Activities ( = .005), and Quality of Life ( = .006) subscales using multivariable linear regression analysis. The postoperative JLCA was not related to the improvement in the ICRS grade of the MFC but was related to the improvement in the ICRS grade of the MTP, with a cutoff value of 1.6° (sensitivity, 0.704; specificity, 0.603; = .015). Furthermore, postoperative JLCA was related to the KOOS Pain ( = .004), Symptoms ( = .002), Activities of Daily Living ( = .031), Sports Activities ( < .001), and Quality of Life ( = .015) subscales.

CONCLUSION

A smaller pre- and postoperative JLCA was related to improvements in the ICRS grade and favorable clinical outcomes, with a mean 5.5-year follow-up after OWHTO.