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

Purpose: Frailty is a complex clinical syndrome characterized by reduced physiological reserves, which is reportedly associated with postoperative adverse outcomes and may increase the risk of postoperative pain. Our study aimed to explore whether frailty was an independent risk factor for pain after total knee arthroplasty (TKA) in elderly 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 included in the final analysis, 51 patients were identified as being frail. Patients with chronic postsurgical pain (CPSP) had a significantly higher frailty index than those without CPSP, which was the same in patients with acute postoperative pain (APSP). After adjusting for other confounding factors, frailty was shown to be an independent risk factor for both CPSP (OR: 4.242, 95% CI: 1.286–13.997, P  = 0.018) and APSP (OR: 13.232, 95% CI: 3.731–46.929, P  < 0.001). The area under the receiver operating characteristic curve for frailty predicting CPSP was 0.728 ( P  < 0.001, 95% CI: 0.651–0.805). Conclusions Our findings demonstrated that preoperative frailty in elderly patients was a predictor of acute and chronic postoperative pain after TKA, suggesting that the frailty assessment should become a necessary procedure before operations, especially in elderly patients.