Introduction: The histology of prosthetic tissue is a gold standard for the diagnosis of prosthetic joint infection. However, the specificity and sensitivity of histology has never been 100% and this could be due to several causes. A possible cause for inconsistencies in histological results could be the type of specimen submitted to laboratory. The majority of authors obtain specimens from pseudocapsule, interface membrane and any tissue area suspicious of infection.

Aim: The objective of our study was to elucidate which is the most accurate specimen for histological diagnosis of prosthetic joint infection.

Methods: Prospective study including all revision arthroplasties performed in Hospital Clinic of Barcelona (Spain) from January 2007 to June of 2009. Specimens from pseudocapsule and from interface membrane were obtained from each patient. Definitive diagnosis of infection was considered when ≥2 cultures were positive for the same microorganism or the presence of pus around the prosthesis. Patients were classified in two groups:

patients submitted to hip revision arthroplasty due to an aseptic loosening in whom cultures (at least 5) obtained during surgery were negative and

Results: A total of 69 revisions were included in the study; 57 were classified in the group A and 12 were classified in the group B. The percentage of positive interface membrane histology in patients with prosthetic joint infection (group B) was significantly higher than the percentage of positive pseudocapsule histology (83.3% vs 41.6%, p=0.04, Fisher exact test).

Conclusion: The results suggest that the best specimen of periprosthetic soft tissue for histological study to diagnose the chronic periprosthetic infection in a revision total hip arthroplasty is the periprosthetic interface membrane.

Exchange of infected implant using antibiotic-impregnated cement is the treatment of choice in prosthetic joint infection (PJI). We presented our experience using one or two-stage exchange with uncemented implants.

From January 2000 to June 2006 patients with a PJI that were treated with one or two-stage exchange with uncemented implants, were prospectively followed up. The treatment protocol consisted of radical excision of devitalized tissue and of maintaining a high serum antibiotic concentration during surgery followed by systemic antibiotic administration according to the microbiology results. Only patients with ≥6 months of follow-up were included. Good evolution was considered when symptoms and signs of infection disappeared and the C-Reactive Protein was normal.

Forty-two patients were included in the study, of whom 25 were male. The mean age was 70 years. The most common symptom was pain (100%) and radiological signs of prosthesis loosening were present in 36 cases (85.7%). Histology was positive in 32 patients (76.2%). Coagulase-negative staphylococci was the most common microorganism (23 cases) followed by S. aureus (5 cases). One-stage exchange was performed in 18 patients, and the long stem component was always uncemented. In one case an acute infection after the arthroplasty obligated to perform an open debridément without implant removal. After a mean follow-up of 31 months (range: 6–84) all patients had a good evolution. In 24 cases a 2-stage exchange with a joint spacer with gentamycin (Spacer-G) was performed. In all cases the definitive arthroplasty was performed using an uncemented long stem. Good evolution was documented in all but one case with persistent infection due to S. aureus after a mean follow-up of 19 months (range: 12–48).

Our results suggest that uncemented arthroplasty following a protocol based on radical debridément and systemic antibiotic therapy during and after surgery is a useful approach in PJI.