Identification of Asymptomatic Prosthetic Joint Infection: Microbiologic and Operative Treatment Outcomes.

BACKGROUND: This prospective study investigated the role of mechanical and biological factors in aseptic implant loosening or presumed silent prosthetic joint infection (PJI). METHODS: Thirty-seven patients were investigated. Microbiologic and molecular methods were used to detect bacteria on the surface of the failed implants removed during revision arthroplasty. Histopathologic analysis was performed. The influence of body mass index (BMI) and various co-morbidities on implant failure also was determined. RESULTS: The results of sonicated fluid cultures were positive for bacteria in 29.7% and the results of intra-operative tissue and joint liquid cultures in 18.9% and 16.2%, respectively. Molecular detection with 16S rRNA sequencing revealed a large variety of bacteria. The most frequent organism was coagulase-negative Staphylococcus (CNS). The outcomes of histopathologic tests of peri-prosthetic tissue showed evidence of the infection type in all culture-positive joints and in 41.4% of the cases with negative culture results. Overweight status or obesity was present in 82.8% of the culture-negative patients. CONCLUSIONS: The results of this study proved the presence of micro-organisms on the surface of implants in both aseptic and presumed PJI cases. Inclusion of the sonication procedure in the diagnostic algorithm increased the ability to identify the pathogen. The results of our study suggest the co-existing roles of BMI and the time to implant loosening as well as biological agents in causing prosthesis loosening.

Identification of silent prosthetic joint infection: preliminary report of a prospective controlled study.

PURPOSE: We will test the hypothesis that ultrasound supported by polymerase chain reaction (PCR) could improve bacterial identification in non-infected prosthetic joint loosening. The aim was to detect bacterial species in non-infected prosthetic joint loosening using ultrasound and 16S rRNA gene sequencing. METHODS: A total of 16 patients (11 women and five men) aged 46-80 years (mean age 65.7) with diagnosed knee or hip implant loosening (mean implant survival of 102.1 months) were investigated. Bacterial culture and DNA sequencing were used to detect bacteria on the surface of failed implants removed during revision arthroplasty. The results of pre- and intraoperative culture and DNA sequencing were compared. Histopathological analysis was also performed. RESULTS: The number of positive cultures rises with a higher level of C-reactive protein (CRP). The results of the cultures from synovial fluid obtained through joint aspiration were consistent with sonicates from components of prostheses in 12 cases (75%). Bacterial DNA was found in 90% of patients with negative synovial fluid culture. PCR revealed two or more bacterial species, often of the same genus: Ralstonia pickettii, Pseudomonas spp., Brevibacterium spp., Lactobacillus spp., Propionibacterium spp. and Staphylococcus spp.These are micro-organisms present in the environment or on the human body and often associated with compromised immunity. CONCLUSIONS: The ultrasound procedure followed by PCR and sequencing improve bacterial identification in silent prosthetic joint infection. The lack of clinical signs of infection and negative preoperative and intraoperative cultures do not exclude the presence of micro-organisms on the implants.

Neglected, developmental hip dislocation treated with external iliofemoral distraction, open reduction, and pelvic osteotomy.

Between 1995 and 2003, we operated upon 18 children with 20 hips involved, aged 5-11 years (average: 7.5 years) suffering from an inveterate high developmental dislocation of the hip joint. An average follow-up period of our middle-term study was 51 months (range: 34-96 months). A two-staged management was applied. First, femoral head was lowered back to the level of acetabulum with an external fixator or a distractor device. The second stage involved open reduction combined with pelvic osteotomy and, in four cases with femoral derotation osteotomy. We noted two cases of avascular necrosis. Equal limb length was achieved in 15 cases. There were two cases of 0.5-cm length discrepancy, two cases of 1-cm length inequalities, and one case of 5-cm limb shortening. We endorse this method in neglected cases of previously untreated unilateral high developmental hip dislocations in children aged 8-10 years. It results in a usable hip joint without the need of femoral shaft shortening and facilitates future joint replacement.