Patients with osteoarthritis and avascular necrosis have better functional outcomes and those with avascular necrosis worse pain outcomes compared to rheumatoid arthritis after primary hip arthroplasty: a cohort study

BACKGROUND: This study was conducted to assess whether patient-reported outcomes (PROs) differ by the underlying diagnosis (rheumatoid arthritis (RA)/inflammatory arthritis, osteoarthritis (OA), avascular necrosis of bone (AVN), other) in patients undergoing primary total hip arthroplasty (THA). METHODS: We used prospectively collected data to assess the association of diagnosis with index hip function and pain. Moderate-severe activity limitation and moderate-severe pain were assessed at two- and five-year follow-up after primary THA using multivariable-adjusted logistic regression analyses. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. RESULTS: There were 5,707 primary THAs at two-years and 3,289 at five-years, 51% were women and the mean age was 65 years. The underlying diagnosis was RA in 3%, OA in 87%, AVN in 7% and other in 3%. In multivariable-adjusted analyses, compared to RA, diagnoses of OA and AVN were significantly associated with lower odds of moderate-severe activities of daily living limitations with an OR (95% CI) of 0.5 (0.3 to 0.8) (P = 0.01) and 0.4 (0.2 to 0.8) (P = 0.01), respectively, at two-years, but not at five-years, 0.7 (0.4 to 1.4) (P = 0.36) and 0.9 (0.4 to 1.8) (P = 0.78), respectively. At two-years, neither OA nor AVN were significantly associated with higher odds of moderate-severe pain (1.6 (0.6 to 4.5) (P = 0.40) and 2.8 (0.9 to 8.5) (P =0 0.06)), respectively. At five-years, AVN was associated with higher odds of moderate-severe pain with OR 4.1 (1.2 to 14.1) (P = 0.02), but not OA, 2.1 (0.7 to 6.5) (P = 0.22). CONCLUSIONS: We found that patients with OA and AVN had better functional outcomes and those with AVN worse pain outcomes after primary THA, compared to patients with RA/inflammatory arthritis. Insights into mediators of these relationships are needed to better understand these associations

C-Reactive Protein, Erythrocyte Sedimentation Rate and Orthopedic Implant Infection

BACKGROUND: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been shown to be useful for diagnosis of prosthetic hip and knee infection. Little information is available on CRP and ESR in patients undergoing revision or resection of shoulder arthroplasties or spine implants. METHODS/RESULTS: We analyzed preoperative CRP and ESR in 636 subjects who underwent knee (n=297), hip (n=221) or shoulder (n=64) arthroplasty, or spine implant (n=54) removal. A standardized definition of orthopedic implant-associated infection was applied. Receiver operating curve analysis was used to determine ideal cutoff values for differentiating infected from non-infected cases. ESR was significantly different in subjects with aseptic failure infection of knee (median 11 and 53.5 mm/h, respectively, p=<0.0001) and hip (median 11 and 30 mm/h, respectively, p=<0.0001) arthroplasties and spine implants (median 10 and 48.5 mm/h, respectively, p=0.0033), but not shoulder arthroplasties (median 10 and 9 mm/h, respectively, p=0.9883). Optimized ESR cutoffs for knee, hip and shoulder arthroplasties and spine implants were 19, 13, 26, and 45 mm/h, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 89 and 74% for knee, 82 and 60% for hip, and 32 and 93% for shoulder arthroplasties, and 57 and 90% for spine implants. CRP was significantly different in subjects with aseptic failure and infection of knee (median 4 and 51 mg/l, respectively, p<0.0001), hip (median 3 and 18 mg/l, respectively, p<0.0001), and shoulder (median 3 and 10 mg/l, respectively, p=0.01) arthroplasties, and spine implants (median 3 and 20 mg/l, respectively, p=0.0011). Optimized CRP cutoffs for knee, hip, and shoulder arthroplasties, and spine implants were 14.5, 10.3, 7, and 4.6 mg/l, respectively. Using these cutoffs, sensitivity and specificity to detect infection were 79 and 88% for knee, 74 and 79% for hip, and 63 and 73% for shoulder arthroplasties, and 79 and 68% for spine implants. CONCLUSION: CRP and ESR have poor sensitivity for the diagnosis of shoulder implant infection. A CRP of 4.6 mg/l had a sensitivity of 79 and a specificity of 68% to detect infection of spine implants