Several studies have investigated the influence of body mass index (BMI) on functional gain after total hip replacement (THR) or total knee replacement (TKR) in osteoarthritis, with contradictory results. This systematic literature review was conducted to ascertain whether obesity affects functional recovery after THR or TKR in the short (<1 year), medium (<3 years) and long term (>3 years).

The study was registered with PROSPERO and conducted according to the PRISMA guidelines. A systematic literature search was conducted across Medline and EMBASE databases for articles published between 1980 and 2020 that investigated patient-reported measures of functional recovery after THR and TKR in participants with osteoarthritis and obesity (defined as BMI ≥30 kg/m²).

Twenty-six articles reporting on 68,840 persons (34,955 for THR and 33,885 for TKR) were included in the final analysis: 5 case-control studies, 21 cohort studies (9 for THR only, 10 for TKR only and 2 for both). The average minimum follow-up was 36.4 months, ranging from 6 weeks to 10 years. Most studies found significantly lower pre-operative patient-reported functional scores for participants with obesity. After THR, there was a small difference in functional recovery in favor of those without obesity in the short term (<6 months), but the difference remained below the minimal clinically important difference (MCID) threshold and disappeared in the medium and long term. After TKR, functional recovery was better for those with obesity than those without in the first year, similar until the third year, and then decreased thereafter.

Although there is a paucity of high-quality evidence, our findings show substantial functional gains in people with obesity after total joint replacement. Functional recovery after THR or TKR does not significantly differ, or only slightly differs, between those with and without obesity, and the difference in functional gain is not clinically important.

CRD42018112919.