Comparison of Total Hip Replacement vs. Total Knee Replacement Outcomes
Total knee replacement demonstrates superior pain relief and functional improvement compared to non-surgical treatment, while total hip replacement lacks direct comparative evidence with non-surgical approaches but shows similar patient-reported outcomes to total knee replacement when directly compared. 1, 2
Evidence for Total Knee Replacement (TKR)
- A 2015 randomized controlled trial found that total knee replacement followed by non-surgical treatment resulted in greater pain relief and functional improvement after 12 months compared to non-surgical treatment alone (exercise, education, dietary advice, insoles, and analgesics) 1
- However, TKR was associated with a high number of serious adverse events 1
- National guidelines recommend TKR for end-stage osteoarthritis of the knee, with evidence now supported by randomized controlled trial data 1
Evidence for Total Hip Replacement (THR)
- No randomized controlled trials have compared total hip replacement with non-surgical treatment, placebo, or sham surgery for end-stage osteoarthritis 1
- A 2024 randomized controlled trial comparing THR with resistance training in patients with severe hip osteoarthritis found THR resulted in clinically important, superior reduction in hip pain and improved function at 6 months (mean improvement in Oxford Hip Score of 15.9 points for THR vs. 4.5 points for resistance training) 3
- National guidelines recommend THR for end-stage osteoarthritis of the hip, but these recommendations were historically based on observational retrospective studies using prosthesis survival as the primary outcome measure 1
Direct Comparison of THR vs. TKR Outcomes
- A 2023 prospective longitudinal observational study comparing THR and TKR found no significant differences in post-operative patient-reported outcome measures (PROMs) between the two procedures 2
- Both THR and TKR demonstrated significant post-operative improvements in all PROM scores (P < 0.001) 2
- No significant differences were found in:
- Hip and Knee Osteoarthritis Outcome scores (P = 0.140)
- Western Ontario and McMaster Universities Osteoarthritis Index pain (P = 0.297), stiffness (P = 0.309), and function (P = 0.945)
- Oxford Hip and Knee Score (P = 0.076)
- EuroQol-5D index (P = 0.386)
- Short-Form 12-item survey physical component score (P = 0.106) 2
Complications and Special Considerations
- When comparing THR in rheumatoid arthritis (RA) vs. osteoarthritis (OA) patients, those with RA have higher risks of:
- Revision (OR=1.15,95% CI, 1.02-1.29)
- Hip dislocation (OR=2.31,95% CI, 1.67-3.20)
- Periprosthetic infection (OR=1.44,95% CI, 1.29-1.61)
- Wound infection (OR=2.15,95% CI, 1.19-3.90) 4
- Obesity has a greater negative influence on outcomes following TKR than THR 2
- When comparing THR with hip resurfacing arthroplasty:
- Evidence on functional outcomes, failure rate, and mortality was inconclusive
- Risks of revision and component loosening were higher with resurfacing arthroplasty
- Risk of implant dislocation was lower with resurfacing arthroplasty
- THR had a higher risk of infections 1
Clinical Implications
- Both THR and TKR are effective treatments for severe osteoarthritis, with significant improvements in pain relief and functional outcomes 2, 5
- The decision for referral to orthopedic surgery should be considered for all patients with moderate-to-severe chronic hip or knee pain and disability 5
- Surgery is expensive and associated with considerable morbidity, increased risk of complications, and potential mortality, making high-level evidence crucial for clinical decision-making 1
- When high-level evidence shows non-operative care is equivalent, surgery should be carefully considered 1
- For THR, the assumption that all improvement is due to surgery may overlook contributions from natural history, regression to the mean, or non-replacement co-interventions 1