Preoperative frailty predicts postoperative pain after total knee arthroplasty in older patients: a prospective observational study

Purpose Frailty is reportedly associated with postoperative adverse outcomes and may increase the risk of post-surgical pain. Our study aimed to explore whether frailty was an independent risk factor for pain after total knee arthroplasty (TKA) in older patients. Methods Included in this prospective observational study were patients aged 65 or older who underwent primary TKA. Frailty of the patients was assessed before surgery using the comprehensive geriatric assessment-frailty index and pain was evaluated before and after surgery using the Numerical Rating Scale. Results Of the 164 patients including 125 females with a mean age of 71.4 +/- 4.6 years, 51 patients were identified as being frail. Patients with chronic post-surgical pain had a significantly higher frailty index than those without chronic post-surgical pain, which was the same in patients with acute post-surgical pain. After adjusting for other confounding factors, frailty was shown to be an independent risk factor for both acute (OR: 13.23, 95% CI 3.73-46.93, P < 0.001) and chronic post-surgical pain (OR: 4.24, 95% CI 1.29-14.00, P = 0.02). The area under the receiver operating characteristic curve for frailty predicting chronic post-surgical pain was 0.73 (P < 0.001, 95% CI 0.65-0.81). Conclusions Our findings demonstrated that preoperative frailty in older patients was a predictor of acute and chronic post-surgical pain after TKA, suggesting that frailty assessment should become a necessary procedure before operations, especially in older patients.