Given that medial open wedge high tibial osteotomy (OWHTO) not only delays the progression of osteoarthritis but also alleviates the resulting pain, surgical outcomes would be improved if limited ROM can also be managed. In this regard, the effect of concurrent notchplasty on flexion contracture has not been evaluated.

(1) Concurrent notchplasty in OWHTO would relieve flexion contracture regardless of the severity of osteoarthritis and this effect would be maintained over time, and (2) concurrent notchplasty would not cause any added complications compared to the same procedure without notchplasty.

In total, 107 patients who underwent OWHTO between 2011 and 2017 with a mean follow-up period of 46.6 months (range, 24–102 months) were reviewed. ROM was measured at three time points as follows: before surgery, at 6–12 months postoperatively, and at the latest follow-up. The measurements were analyzed using a linear mixed model in terms of notchplasty and other factors, including age, sex, body mass index, preoperative hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle, correction angle, concurrent meniscectomy, postoperative posterior slope, and Kellgren-Lawrence grade. Then, ROMs at the three time points were compared between the notchplasty and non-notchplasty groups.

Of the 107 patients, 47 underwent concurrent notchplasty. The linear mixed model regarding flexion contracture showed a significant notchplasty-by-time interaction (p<001). When comparing preoperative flexion contractures between the two groups, a significant difference was found (p<001). At 6–12 months postoperatively, flexion contractures were relieved regardless of notchplasty; however, the difference between the groups was decreased (p=026). At the latest follow-up, flexion contractures were partly aggravated in both groups, but no significant difference was found between the groups (p=461). Comparison of flexion contracture between before surgery and at the latest follow-up in each group revealed a significant difference only in the notchplasty group (p<001, with notchplasty; p=197, without notchplasty). The linear mixed model regarding maximal flexion did not show any factor having a significant interaction with time. There were no surgical complications such as infection, thromboembolic events, and hemarthrosis, in both notchplasty and non-notchplasty groups.

The preoperative difference in flexion contracture was overcome by adding notchplasty to OWHTO, and this improvement was maintained over time. No added complications were noted in the notchplasty group. The results should be interpreted with caution, considering measurement error of ROM. However, concurrent notchplasty in OWHTO deserves further study to validate its efficacy.

III, retrospective cohort study.