Patients Who Are Older, Have High BMI May Respond to Knee OA Surgery

A response rate of 78% to medial opening wedge high tibial osteotomy (HTO) for knee osteoarthritis (OA) was reported in a study published in The Journal of Rheumatology.

The response rate and predictors for response to medial opening wedge HTO for the treatment of knee OA have not been fully elucidated.

Patients with knee OA who underwent medial opening wedge HTO at Fowler Kennedy Sport Medicine Clinic in Canada between 2002 and 2014 were evaluated for response through 2 years.

Response to treatment was defined as at least 20% relative improvement with a 10-point or more absolute change in pain and function compared with baseline.

A total of 523 patients were included in the study, with a mean age of 46.6 (SD, 9.1) years; 77.4% were men. The preoperative mechanical axis angle was -7.8 ° (SD, 3.7 °), Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score was 50.3 (SD, 17.7) points; KOOS function in daily living score was 59.1 (SD, 19.9) points; and 23.5% had Kellgren-Lawrence grade 4 at baseline.

At follow-up, 78% of patients had a response at a relative threshold improvement of at least 20%, 32% had a response of at least 50% improvement, and 20% had a response of at least 70% improvement.

Treatment response of at least 20% was associated with age per 10-year increase (odds ratio [OR], 1.34; 95% CI, 1.28-1.40), BMI per 5 increase (OR, 1.21; 95% CI, 1.09-1.33), and postoperative alignment (OR, 1.04; 95% CI, 1.01-1.07). Predictors of response of at least 50% included age (OR, 1.35; 95% CI, 1.03-1.77) and KOOS pain score per 20-point increase (OR, 0.17; 95% CI, 0.13-0.21). Finally, response of at least 70% included the female sex (OR, 1.33; 95% CI, 1.05-1.69), age (OR, 1.26; 95% CI, 1.03-1.55), BMI (OR, 0.89; 95% CI, 0.82-0.95), moderate to severe vs mild to moderate Kellgren-Lawrence grade (OR, 0.82; 95% CI, 0.67-0.99), and KOOS pain subscale score (OR, 0.11; 95% CI, 0.10-0.13).

Stratified by sex, predictors of response at the 20% or more threshold among men included BMI (OR, 1.56; 95% CI, 1.39-1.74), age (OR, 1.33; 95% CI, 1.22-1.45), and postoperative alignment (OR, 1.05; 95% CI, 1.00-1.10), and among women, they included age (OR, 1.59; 95% CI, 1.31-1.93), BMI (OR, 0.83; 95% CI, 0.70-0.97), and moderate to severe Kellgren-Lawrence grade (OR, 0.46; 95% CI, 0.31-0.69).

A significant sex-by-pain interaction was observed, in which less pain at baseline predicted response among women (OR, 1.25; 95% CI, 1.02-1.52) but not men (OR, 0.86; 95% CI, 0.67-1.09).

A major limitation of the study was the lack of a comparator cohort.

The study authors concluded, [P]atients who are older and have a higher BMI can also experience sizable pain and function responses from HTO surgery.” They also noted, “[T]his is the first study to evaluate sex differences in pain response after HTO through responder criteria.”

This article originally appeared on Rheumatology Advisor