Periprosthetic low-grade hip infections. Erythrocyte sedimentation rate and C-reactive protein in 23 cases

We followed 23 patients from the primary total hip arthroplasty to revision for a bacteriologically proven deep infection with a low virulent organism. The median time to revision was 14 (4-65) months. During this period, the maximum ESR value was median 50 (22-110) mm and the maximum CRP value was 35 (9-95) mg/L. 25 of the 98 CRP values recorded were normal (< 9 mg/L) and 22/89 ESR values were below 30 mm/h. In 6 patients, all CRP values were below 20 mg/L, but 5 of these patients had an ESR > 30 mm. Before the revision, normal values for both tests were found in only 1 patient. Both normal values and slight-to-moderate increases in ESR and/or CRP are consistent with a low-grade periprosthetic hip infection. We recommend that ESR should be determined preoperatively in all patients scheduled for total hip replacement to establish a baseline.