Is it Really Less Painful to Undergo Total Hip Arthroplasty than Total Knee Arthroplasty?

BACKGROUND: Severe hip and knee osteoarthritis can produce major pain, pain-related disability, and functional limitations. While total hip (THA) and knee (TKA) arthroplasties can provide pain relief in these populations, an assessment and comparison of their postoperative course of improvement in pain scores is lacking. METHODS: In this retrospective review, patients who underwent unilateral THA or TKA between November 2018 and December 2023 and used a web-based home therapy program were included. In total, 1,373 THA and 1,428 TKA patients were included. Daily Visual Analog Scale (VAS) pain scores (0 to 10) were followed from 30 days preoperatively to 90 days postoperatively across all patients. Mean pre- and post-operative plateaus in pain scores were compared across all cohorts using multivariate linear regression analyses. The THA patients had lower mean age, percent women, and mean body mass index (P < 0.05). RESULTS: Preoperatively, THA patients reported a 0.7 point higher mean pain score (P < 0.001). Within one week of surgery, THA patients noted a 1.8 points larger drop in pain scores. Postoperatively, THA patients noted an earlier drop (within the first versus within the second week) and plateau (58 versus 77 days) in pain scores and had a 0.9 point lower mean plateau pain score (P < 0.001) than TKA patients. After stratification by history of narcotics use, THA and TKA patients who reported preoperative narcotics use had a 0.6 point and 0.4 point higher mean preoperative pain score, respectively (P < 0.001). These patients achieved an earlier plateau in pain scores across both cohorts (THA: 53 versus 58 days; TKA: 54 versus 78 days), but had a 1.1 and 1.1 point higher mean postoperative pain score, respectively (P < 0.001). CONCLUSION: While THA patients had more severe pain preoperatively, they experienced more immediate improvements in their pain outcomes, achieved an earlier plateau in their scores, and had lower postoperative pain than TKA patients. Preoperative narcotics use significantly worsened the postoperative course for both cohorts.