Background

To date, there remains a scarcity of evidence evaluating clinical outcomes after double level osteotomy (DLO) for severe symptomatic varus malalignment. Thus, the aim of this study was to evaluate the clinical outcomes as well as return to sports (RTS) and work (RTW) rates following DLO, and to compare these outcome parameters among patients undergoing a single surgery or two-stage procedure. It was hypothesized that patients undergoing DLO would achieve significant improvement in functional outcomes along with high RTS and RTW rates, and that there would be no difference in outcomes between single-stage and two-stage procedures at a minimum 2-year follow-up.

Methods

Thirty-two consecutive patients with a mean age of 44±13 years who underwent DLO for symptomatic varus malalignment at the senior author's institution between December 2007 and March 2018 and had a minimum 2-year follow-up were enrolled in the study. Outcome measures included the international knee documentation committee (IKDC) score, Lysholm score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Tegner Activity Scale, and visual analogue scale for pain (VAS), which were collected preoperatively and at a minimum of two years postoperatively. Return to sports and work were evaluated by questionnaire. These outcome measures were further compared between patients who underwent DLO in a single operation versus a two-stage approach in a subgroup analysis. An a priori power analysis was performed to determine the sample size allowing for detecting the minimal clinically important difference of the WOMAC score (15 points). Assuming a common standard deviation of 10 points, a total sample size of 18 subjects would provide 80% power to detect a 15 points difference in WOMAC score at an a level of 0.05.

Results

Mean follow-up was 56.9±35.3 months (range 24-148). Compared to preoperatively, patients significantly improved in IKDC (50.4±13.9 to 66.1±15.4, p<.001; 95%CI=10.5-21.5), WOMAC (29.7±19.2 to 11.8±13.5; p<.001; 95%CI=27.0–12.5) and Lysholm (53.6±23.6 to 73.1±23.6; p=.002; 95%CI=7.5–30.5) scores along with significant reduction of pain (5.0±3.0 to 2.5±2.4; p<.001; 95%CI=4.0–2.0) at final follow-up. Postoperatively, 96% of patients returned to sports at a mean of 7.7±4.8 months. However RTS was observed at a lower frequency (10.8±7.3 vs 8.2±7.5 h/week; p=0.01) and to fewer disciplines (3.3±2.0 vs. 2.6±7.3; p=0.005) with a shift in disciplines to low-impact sports, with an overall tendency to improvement of the Tegner activity level (3.3±2.1 to 3.7±1.6; p>0.05). 90% of the patients returned to work at a mean 5.9±9.4 months, with 79% reporting a similar or superior working ability. While it took patients undergoing a two-stage procedure significantly longer to fully return to work (9.0±13.1 vs 9.8±3.8 months, p=0.047; 95%CI=7–0), no other outcome measures significantly differed between patients undergoing a two-stage compared to a single-stage procedure.

Conclusion

Patients undergoing DLO for severe symptomatic varus malalignment experienced clinically significant functional improvement at minimum 2-year follow-up. Return to sports and work rates are high, however, a shift to lower impact sports disciplines has to be expected. Similar clinical outcomes can be expected when performing DLO via single surgery or a two-stage procedure.