Aim

Septic arthritis of the hip is a rare entity among the adult population, but with a potential severe repercussion. The most accepted treatment is the hip debridement, even though a notorious proportion of the cases need further hip replacement owing to the cartilage destruction. The aim of this study is to analyse all our cases of septic arthritis of the hip treated with a 2-stage strategy using an antibiotic-loaded cement spacer.

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.

Introduction: The most important cause of prosthetic joint infection (PJI) is the contamination of the wound during the surgery. Nowadays, it doesn’t exist any image or laboratory test for early detection of prosthesis with a higher risk of developing a PJI.

Aim: The primary aim was to evaluate the usefulness of different intraoperative samples during the surgery of implantation of a primary hip arthroplasty (PHA) as a predicting factor of PJI.

Methods: A prospective cohort study was performed. All patients (n= 278) who underwent a PHA from January ’06 to November ’08 were included. Three samples: a piece of articular capsule (TS), a swab (S) and synovial fluid (SF) inoculated into blood flask were taken in each patient during the first 45 minutes of surgery. Other possible risk factors of PJI like age, sex, ASA, comorbidity and surgical time were registered.

Results: A total of 278 patients were included. 30 cultures (8 SF, 13 TS and 9 S) were positive in 29 patients. The most frequent microorganism isolated was Coagulase-negative staphylococci (CNS) (66.6%). The rate of PJI (early and late) in the subgroup of patients with positive intraoperative cultures for CNS was 25% while in the subgroup with all negative cultures was 5.2% (RR=4.8; p=0.007). Other factors significantly associated with a higher rate of PJI in the univariate analysis were: ASA III (RR=9.12; p=0.02), cardiopathy (RR= 2.82; p=0.04), obstructive pulmonary chronic disease (RR=5; p=0.02) and rheumatoid arthritis (RR=4.16; p=0.04). Multivariate analysis found ASA III (Odds ratio 10.9; CI 95% 1.27–94.6; p=0.02) and a positive intraoperative culture for CNS (Odds ratio 5.92; CI 95%=1.8–19.85; p=0.03) as independent risk factors for PJI.

Conclusion: Positive intraoperative culture for CNS during PHA was independently associated with the development of PJI.

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.

Intraoperative histology has a high specificity and sensitivity to identify prosthetic joint infection. However, the usefulness of this technique according to the type of microorganism isolated in the periprosthetic tissue has not previously been studied.

Frozen sections and cultures from periprosthetic tissue of 38 revision arthroplasties performed due to prosthetic joint infection were retrospectively reviewed. Frozen sections were evaluated according to Mirras’ criteria (adapted by Feldman). Culture was considered positive when the same microorganism was isolated in at least 2 samples or the presence of pus around the prosthesis.

Coagulase-negative staphylococci (CNS) was the aetiology in 13 cases, Gram-negative bacilli in 8, S. aureus in 7, Candida sp and Peptococcus sp in 2 and Enterococcus sp, S.pneumoniae and in 1 case each one. No microorganism was isolated in 4 cases. Frozen sections revealed more than 5 neuthrophils per high power field (forty times) in at least five fields in all cases except in 2 out of 13 caused by CNS (15.3%). A revision of the articles that provided information on the aetiology and the histology supports the findings of our study.

In conclusion, frozen section using Feldman’s criteria had a 15.3% of false negative cases when CNS was the aetiology of the prosthetic joint infection.

Purpose: To review the results of periprosthetic femoral fractures treated using cortical strut allograft and plate internal fixation.

Material & Methods: Between November 1996 and July 2006, 17 patients with periprosthetic fractures of the femur after hip arthroplasty were treated using deep-frozen cortical strut allografts as an adjunct support after internal fixation. The average age was 79 years (range 56 to 96 years) with 13 woman and 4 men. According to the Vancouver classification system, there were 6 type B1, 5 type B2, 1 type B3 and 5 type C fractures. All fractures were closed except for one type I of Gustilo. Twelve patients had internal fixation of the fracture using a Dall-Miles cable and plate system, 5 using a AO/ASIF 4.5 dynamic compression plate, and 2 had an associated revision arthroplasty of the stem. Cortical strut allograft was used from the femur in 6 cases and from the tibia in 11 cases. Mean follow-up was of 97.5 weeks.

Results: One patient presented a rupture of a screw and varus displacement of the fracture, but healed without symptomatic complaints. A superficial infection occurred in the patient with open fracture. All the patients, except for two, required allogenic blood transfusion. Mean inhospital stay was of 18.6 days and walk with weigh was allowed at a mean of 50.9 days. Two patients died few weeks after the treatment due to complications of their previous pathological disorders. Aseptic loosening of a hip arthroplasty occurred at two years follow-up requiring revision surgery. Three patients referred mild pain at the last follow-up visit.

Conclusions: Cortical strut allograft associated with internal fixation has provided satisfactory results in the present serie. We consider this procedure safe and effective, specially for type B1 and C periprosthetic femoral fractures.

Aims: The study we present compares quantitatively the bone regeneration in experimental animals obtained with autologus and homologus grafts against a calcium phosphate cement. Methods: We performed cavitary defects o 6 mm of diameter in the metaphiseal region of the distal femur of 48 rabbits of albine race. They were divided in 4 groups, and received respectively autologous grafts, homologous freezed graft, calcium phosphate cement or the absence of any implant (control group). Results: The results are valued by radiological, histological and histomorphometrical studies (with digitalysed images). Histological study shows a correct integration of the calcium phosphate cement, without þbrous interphase, and a bone regeneration which is progressive and centripetal. Statistical analysis of the histomorphometrical data shows that bone regeneration obtained with the calcium phosphate cement its similar to the one obtained with the grafts. Conclusions: Calcium phosphate cement is a biocompatible material, biodegradable and conductor.

Introduction and Objectives: Periprosthetic fractures present some difficult problems: the inability to use intramedullary implants, difficulty in inserting screws (since the cavity is occupied), bone fragility, great mechanical demands, elderly patients, and associated conditions. We have used two osteosynthesis reinforcement techniques in these cases: massive intramedullary cementation and implantation of bone allograph counterplates. Both techniques give a simple solution for complex peri-prosthetic fractures.

Materials and Methods: We used this technique to treat 9 periprosthetic fractures of the femur between 1999 and 2003. In 3 cases, massive intramedullary cementation was used (Johansson type III, distal to the prosthetic stem) and in 6 cases a bone allograft counterplate (Johansson type II, around the prosthesis), associated with the stem replacement in 2 cases. Allografts came from the Tissue Bank of the Institut Clinic de l’Aparell Locomotor (ICAL). There were 7 females and 2 males, with an average age of 76 years (range: 66–83). Average follow-up time was 14 months (range: 6 months to 3.5 years).

Results: In 8 of 9 cases (89%), fracture consolidation was achieved in 3.5 months, with patients regaining the same ability to walk as before the injury. In one case with intramedullary cementation, non-union developed with breakage of the plate at 10 months post-intervention. This case was treated with compression osteosynthesis with a new plate and bone allograft counterplate, and final outcome was satisfactory (consolidation at 4 months) with the patient walking with full weight bearing without crutches.

Discussion and Conclusions: We believe both techniques are useful in the resolution of periprosthetic fractures of the femur over porous bone. However, a very precise surgical technique is necessary, as well as respect for the classical principles of osteosynthesis: fracture fixation with anatomic reduction, interfragmentary compression, and maximum care afforded soft tissue.