In patients with an unsatisfactory response to first knee replacement, the best predictor of achieving a satisfactory response to contralateral knee replacement is the level of radiographic osteoarthritis (OA) in that knee, according to a study published in Knee Surgery, Sports Traumatology, Arthroscopy.
“The purpose of this study was to determine whether predictive factors can be found to prognosticate outcome of the second-side knee replacement when a patient has an unsatisfactory response to the first, with the hypothesis that predictors, such as prosthetic factors and radiographic level of OA, may be able to predict a satisfactory response to the contralateral knee replacement,” the researchers noted.
Researchers conducted an analysis of staged bilateral knee replacements performed at a tertiary arthroplasty center from 2012 to 2018. The study included 550 knee replacements in 275 patients. Satisfactory response to surgery was defined as a Western Ontario and McMaster Universities Osteoarthritis Index score that improved by 17 points or more, and 56 or greater. Patients who did not achieve a satisfactory response with their first knee replacement were further analyzed for predictive factors of an unsatisfactory response for their contralateral knee replacement, including age, sex, preoperative score, mental health score, socioeconomic status, type of prosthesis, use of navigation, patella resurfacing, and radiographic OA.
Among the study cohort, 44 patients (16%) failed to achieve a satisfactory response from both their first and contralateral knee replacements. Preoperative mental health score was the biggest predictor of an unsatisfactory response to the first knee replacement. However, in patients who did not achieve a satisfactory response with the first knee replacement, radiographic OA (measured by the Kellgren-Lawrence [KL] score) was the main predictor of satisfactory response for their contralateral knee replacement.
Patients with KL grade 4 OA were likely to have a satisfactory response with contralateral knee replacements (KL grade 4 vs. KL grade 3; odds ratio, 3.57; 95% confidence interval, 1.26-10.03; P=0.016). Patients with KL grade 3 OA were unlikely to have a satisfactory response, while no patient with KL grade 2 OA had a satisfactory response.