Olivier Borens

Propionibacterium acnes: An Underestimated Pathogen in Implant-Associated Infections

The role of Propionibacterium acnes in acne and in a wide range of inflammatory diseases is well established. However, P. acnes is also responsible for infections involving implants. Prolonged aerobic and anaerobic agar cultures for 14 days and broth cultures increase the detection rate. In this paper, we review the pathogenic role of P. acnes in implant-associated infections such as prosthetic joints, cardiac devices, breast implants, intraocular lenses, neurosurgical devices, and spine implants. The management of severe infections caused by P. acnes involves a combination of antimicrobial and surgical treatment (often removal of the device). Intravenous penicillin G and ceftriaxone are the first choice for serious infections, with vancomycin and daptomycin as alternatives, and amoxicillin, rifampicin, clindamycin, tetracycline, and levofloxacin for oral treatment. Sonication of explanted prosthetic material improves the diagnosis of implant-associated infections. Molecular methods may further increase the sensitivity of P. acnes detection. Coating of implants with antimicrobial substances could avoid or limit colonization of the surface and thereby reduce the risk of biofilm formation during severe infections. Our understanding of the role of P. acnes in human diseases will likely continue to increase as new associations and pathogenic mechanisms are discovered.

Epidemiology and new developments in the diagnosis of prosthetic joint infection

Although prosthetic joint infection (PJI) is a rare event after arthroplasty, it represents a significant complication that is associated with high morbidity, need for complex treatment, and substantial healthcare costs. An accurate and rapid diagnosis of PJI is crucial for treatment success. Current diagnostic methods in PJI are insufficient with 10–30% false-negative cultures. Consequently, there is a need for research and development into new methods aimed at improving diagnostic accuracy and speed of detection. In this article, we review available conventional diagnostic methods for the diagnosis of PJI (laboratory markers, histopathology, synovial fluid and periprosthetic tissue cultures), new diagnostic methods (sonication of implants, specific and multiplex PCR, mass spectrometry) and innovative techniques under development (new laboratory markers, microcalorimetry, electrical method, reverse transcription [RT]-PCR, fluorescence in situ hybridization [FISH], biofilm microscopy, microarray identification, and serological tests). The results of highly sensitive diagnostic techniques with unknown specificity should be interpreted with caution. The organism identified by a new method may represent a real pathogen that was unrecognized by conventional diagnostic methods or contamination during specimen sampling, transportation, or processing. For accurate interpretation, additional studies are needed, which would evaluate the long-term outcome (usually >2 years) with or without antimicrobial treatment. It is expected that new rapid, accurate, and fully automatic diagnostic tests will be developed soon.

Nonunions of the Distal Tibia Treated by Reamed Intramedullary Nailing

Objective: The purpose of this study is to determine the efficacy of reamed intramedullary nailing in the treatment of nonunions of the distal one-fourth of the tibia. Nonunions of the distal tibia are particularly difficult to treat given the short distal segment, the proximity to the ankle joint, and the fragile soft-tissue envelope. Intramedullary nailing is an attractive solution to this problem because it avoids extensive dissection, and the implant remains intraosseous, posing minimal problem for the soft tissues. Design: Retrospective review of patient charts and radiographs. Setting: Tertiary care orthopaedic hospital. Patients/Participants: Thirty-two patients with nonunions of the distal one-fourth of the tibia. Prior treatments included casting, internal fixation with plates and screws, intramedullary nailing, and external fixation. Seven patients had a history of infection, but no patient had signs of active infection at the time of surgery. Intervention: Study patients were treated by reamed, locked intra-medullary nailing. Main Outcome Measurements: Main outcome measurements included time to union, correction of deformity, and complications including infection and reoperation. Results: Average length of follow-up was 25 months (range 4–81 months). Twenty-nine out of 32 patients achieved union at an average of 3.5 months after reamed, locked intramedullary nailing. Of the remaining three, 2 patients united after dynamization (one at 4 months after dynamization and the other at 7 months), and the third patient united 4 months after exchange nailing. Deformity was corrected to a maximum of 4° in all planes. Four patients had positive intraoperative cultures, and only 2 required removal of the nail after achieving union to control infection. There were no signs of chronic osteomyelitis in these 2 patients at the date of the last follow-up visit; 5.5 years and 2 years following nail removal. Conclusions: Reamed, locked intramedullary nailing is a reliable and safe procedure in the treatment of nonunions in the distal one-fourth of the tibia, even in the setting of prior infection or external fixation. It allows for excellent correction of deformity, which is an essential component of the procedure.

Biofilm formation on bone grafts and bone graft substitutes: Comparison of different materials by a standard in vitro test and microcalorimetry

We analyzed the initial adhesion and biofilm formation of Staphylococcus aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984) on various bone grafts and bone graft substitutes under standardized in vitro conditions. In parallel, microcalorimetry was evaluated as a real-time microbiological assay in the investigation of biofilm formation and material science research. The materials beta-tricalcium phosphate (beta-TCP), processed human spongiosa (Tutoplast) and poly(methyl methacrylate) (PMMA) were investigated and compared with polyethylene (PE). Bacterial counts (log(10) cfu per sample) were highest on beta-TCP (S. aureus 7.67 +/- 0.17; S. epidermidis 8.14 +/- 0.05) while bacterial density (log(10) cfu per surface) was highest on PMMA (S. aureus 6.12 +/- 0.2, S. epidermidis 7.65 +/- 0.13). Detection time for S. aureus biofilms was shorter for the porous materials (beta-TCP and processed human spongiosa, p < 0.001) compared to the smooth materials (PMMA and PE), with no differences between beta-TCP and processed human spongiosa (p > 0.05) or PMMA and PE (p > 0.05). In contrast, for S. epidermidis biofilms the detection time was different (p < 0.001) between all materials except between processed human spongiosa and PE (p > 0.05). The quantitative analysis by quantitative culture after washing and sonication of the material demonstrated the importance of monitoring factors like specific surface or porosity of the test materials. Isothermal microcalorimetry proved to be a suitable tool for an accurate, non-invasive and real-time microbiological assay, allowing the detection of bacterial biomass without removing the biofilm from the surface.

Anterior tension band plating for anterior tibial stress fractures in high-performance female athletes - A report of 4 cases

Stress fracture of the anterior tibial cortex is an extremely challenging fracture to treat, especially in the high-performance female athlete who requires rapid return to competition. Previous reports have not addressed treating these fractures in the world-class athlete with anterior plating. We hypothesize that anterior plating is a biomechanically sound approach to treatment of these fractures, and will lead to an earlier return to full activity than either nonoperative treatment or intramedullary nailing. We present a retrospective series of 4 case reports of 4 world-class female athletes with stress fractures of the anterior tibial cortex treated by anterior plating between 2001 and 2004. Average follow-up was 15 months (range 12 to 48 mo). Anterior tension band plating resulted in fracture healing in all 4 cases and return to full activity at a mean of 10 weeks. All patients returned to preinjury competitive levels. There were no complications of infection, nonunion, or malunion. Anterior tension-band plating of an anterior tibial stress fracture leads to rapid fracture healing and return to competition for high-performance female athletes. This approach should be considered in those athletes who wish to avoid the more prolonged convalescence associated with nonoperative treatment, or the problems, especially of the knee, associated with intramedullary nailing.

Acute total hip arthroplasty for acetabular fractures in the elderly: 11 patients followed for 2 years.

We describe the use of cable fixation and acute total hip replacement for acetabular fracture in the elderly. 12 patients with acetabular fractures, having a mean age of 79 (65-93) years, were treated with cable fixation and acute total hip arthroplasty. 8 were T-shaped fractures and 4 associated fractures of the posterior column and posterior wall. 1 patient died 5 months after surgery and the remaining 11 were followed for 2 years. All patients had a good clinical outcome. Radiographic assessment showed healing of the fracture and a satisfactory alignment of the cup without loosening. This surgical technique provides good primary fixation, stabilizes complex acetabular fractures in elderly patients with osteoporotic bone and permits early postoperative mobilization.

Diagnosis of periprosthetic joint infections.

Advances in implant design, surgical technique, peri-operative antimicrobial prophylaxis and laminar airflow operating room environment have made total joint arthroplasty one of the most successful surgical procedures of all times. Orthopaedic implants, however, remain prone to microbial contamination resulting in persistent risk of implant-associated infection. Treatment of infections associated with orthopaedic devices usually requires appropriate surgical intervention combined with a prolonged antimicrobial therapy. The choice of the best possible treatment regimen depends on duration and pathogenesis of infection, stability of the implant, antimicrobial susceptibility of the pathogen and condition of the surrounding soft tissue. In addition towell known diagnostic procedures new promising tools for rapid and correct microbial diagnosis are being developed as correct diagnosis of the responsible micro-organism and this is paramount for successful treatment of prosthetic joint infection.

Acute total hip arthroplasty for acetabular fractures in the elderly

We describe the use of cable fixation and acute total hip replacement for acetabular fracture in the elderly. 12 patients with acetabular fractures, having a mean age of 79 (65–93) years, were treated with cable fixation and acute total hip arthroplasty. 8 were T-shaped fractures and 4 associated fractures of the posterior column and posterior wall. 1 patient died 5 months after surgery and the remaining 11 were followed for 2 years. All patients had a good clinical outcome. Radio-graphic assessment showed healing of the fracture and a satisfactory alignment of the cup without loosening. This surgical technique provides good primary fixation, stabilizes complex acetabular fractures in elderly patients with osteoporotic bone and permits early postoperative mobilization.

Anterior subluxation after reduction of a posterior traumatic sterno-clavicular dislocation: a case report and a review of the literature

Sternoclavicular dislocations represent a rare injury. Based on our clinical experience with a patient showing an anterior subluxation after reduction of a posterior traumatic dislocation, we review the literature. The emergent reduction of the dislocation is mandatory, always keeping in mind the potentially devastating neurovascular complications. If the treatment of a residual anterior instability remains controversial, a residual posterior instability should be treated by a surgical procedure. The optimal treatment depends mainly on each surgeon’s choice and practice.

Acute fractures of medial and lateral great toe sesamoids in an athlete

We report a case of acute fracture of both sesamoids of the great toe in an athlete. The fractures healed uneventfully after non-surgical treatment.