Ankle osteoarthritis is a significant cause of pain and disability. Despite the effectiveness of treatments, a subset of patients remains with persistent pain and functional limitations. The purpose of this study was to use preoperative patient-reported outcome measures to predict which ankle osteoarthritis patients would be most likely to experience postoperative improvements in functional outcomes.
A retrospective analysis of prospectively collected data was used to evaluate 427 patients with end-stage ankle arthritis with 5-year follow-up. Demographics, comorbidities, Ankle Osteoarthritis Scale (AOS), Ankle Arthritis Score (AAS), and the physical and mental component scores of the Short Form-36 (SF-36 Physical Components Score [PCS] and Mental Components Score [MCS]) were collected. The minimal clinically important difference (MCID) was then calculated. Receiver operating characteristic (ROC) analysis was used to choose the optimal threshold values of preoperative patient-reported outcome measure and assess the prediction performance.
Patients who scored worst at preoperative baseline made the greatest gains in function and pain relief, and they had a high chance of achieving MCID following surgical treatment. ROC curves demonstrated that preoperative AOS, AAS, and SF-36 PCS and MCS scores were predictive of postoperative improvements in physical and mental function. Patients with preoperative AOS score above 45.7 had an 83% probability of achieving an MCID (AUC = 0.67). Similarly, patients with a preoperative AAS score above 25.7 had a 78% probability of achieving an MCID (AUC = 0.63). Patients with a preoperative SF-36 PCS score below 31 had a 62% probability of achieving an MCID (AUC = 0.64). Patients with a preoperative SF-36 MCS below 52.7 had a 47% probability of achieving an MCID (AUC = 0.89). MCIDs for AOS, AAS, SF3-36 PCS, and SF-36 MCS score changes were 12.4, 10.0, 6.43, and 8.1, respectively.
Level III, prognostic comparative study.
Preoperative patient-reported outcomes measures could predict postoperative improvement in ankle arthritis patients. The results of this study may be used to facilitate discussion between physicians and patients regarding the expected benefit of surgery.