Methicillin-resistant coagulase-negative staphylococci in the community: high homology of SCCmec IVa between Staphylococcus epidermidis and major clones of methicillin-resistant Staphylococcus aureus.

BACKGROUND: Data on community spread of methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are scarce. We assessed their potential role as a reservoir of staphylococcal cassette chromosome mec (SCCmec) IVa, the leading SCCmec subtype in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). METHODS: Nasal carriage of MR-CoNS was prospectively investigated in 291 adults at hospital admission. MR-CoNS were characterized by SCCmec typing, long-range polymerase chain reaction (PCR) for SCCmec IV, and multiple-locus variable-number tandem repeat analysis (MLVA) for Staphylococcus epidermidis (MRSE) strains. Three SCCmec IVa elements were fully sequenced. RESULTS: The carriage rate of MR-CoNS was 19.2% (25.9% and 16.5% in patients with and patients without previous exposure to the health care system, respectively; P = .09). MR-CoNS strains (n = 83, including 58 MRSE strains with highly heterogeneous MLVA patterns) carried SCCmec type IVa (n = 9, all MRSE), other SCCmec IV subtypes (n = 9, including 7 MRSE), other SCCmec types (n = 15), and nontypeable SCCmec (n = 50). Long-range PCR indicated structural homology between SCCmec IV in MRSE and that in MRSA. Complete sequences of SCCmec IVa from 3 MRSE strains were highly homologous to those available for CA-MRSA, including major clones USA300 and USA400. CONCLUSIONS: MR-CoNS are probably disseminated in the community, notably in subjects without previous exposure to the health care system. MRSE, the most prevalent species, may act as a reservoir of SCCmec IVa for CA-MRSA.

Navigated revision knee arthroplasty using a system designed for primary surgery.

While navigation is now recognized as an efficient tool for improving femoro-tibial alignment of primary knee prostheses, its use in revision surgery has not yet been fully evaluated. We describe a procedure based on a bone morphing acquisition performed on the surface of the original implants, followed by a dependant bone cut sequence (tibia first). Using the current system, a preoperative CT-scan measurement of the original femoral component was required. Knee balancing was achieved using spacer blocks, with the trial tibial component and the original femoral component still in place. Preliminary experience from 19 cases, some with severe bone loss requiring reconstruction, is reported. A retrospective comparison to 10 non-navigated revision cases performed concomitantly by the same operating surgeon was carried out. Although there was no significant difference in the number of outliers for the two series, navigation appeared to be a valuable aid in reconstructing both bone extremities, while controlling the level of the joint line. However, definitive validation requires further prospective and comparative investigations in larger series.

The composite meniscal-capsular-fat pad flap in a lateral approach to the fixed valgus knee: an anatomical study.

We present an anatomical study on the vascular supply to the patellar fat pad. Forty knees from fresh cadavers were dissected after injecting the femoral artery with colored latex. In all cases, the vascular supply to the fat pad depended essentially on the lateral inferior genicular artery, which enters this structure at its posterolateral extent. In the cases in which the fat pad flap was raised before the injection of latex, we observed good vascularization of the flap by the lateral genicular artery. This is a safe vascularized flap that offers an optimal covering of knee prostheses in fixed valgus knee deformities. An optimal procedure for raising the flap is proposed.

Survival of total knee replacement with a megaprosthesis after bone tumor resection.

BACKGROUND: The use of a megaprosthesis has become the method of choice for reconstruction after bone tumor resection at the knee. However, the long-term survival of megaprostheses is poor. In this study, we sought to identify factors that were associated with implant failure and amenable to interventions designed to improve implant survival. METHODS: A retrospective review of the charts of ninety-one patients who had undergone resection of a tumor of the knee followed by reconstruction with a custom-made megaprosthesis was performed. The distal part of the femur was resected in fifty-six patients and the proximal part of the tibia, in thirty-five patients. The reconstruction was performed with an allograft-prosthesis composite in thirty-three patients and with metal or plastic sleeves in fifty-eight patients. Reconstruction of the extensor mechanism was necessary in all thirty-five patients with a tibial tumor. RESULTS: The median duration of follow-up was sixty-two months. The extensor mechanism was significantly less likely to rupture when partial continuity had been preserved at the time of the resection. Intra-axial laxity (an arc of motion of >5 degrees in the frontal plane) was significantly more common when the prosthesis had an antirotation pin than when it did not have an antirotation pin (p = 0.0023). There was mechanical failure of ten allograft-prosthesis composites and ten sleeve reconstructions. Thirty-six patients had removal of at least one component of the prosthesis. When revision due to local tumor recurrence was excluded, the median duration of prosthetic survival was 130 months following the distal femoral resections and 117 months following the proximal tibial resections. The median duration of survival was 117 months for the allograft-prosthesis composites and 138 months for the sleeve reconstructions. Body weight and activity level were independent predictors of early revision. CONCLUSIONS: The long-term survival of the knee megaprostheses in this study was poor. Mechanical failure was multifactorial and the leading cause of revision. Use of allograft-prosthesis composites and use of bushings or an antirotation pin appeared to have no mechanical benefits. We recommend that weight control programs and advice about adapting their activity level be offered to patients preoperatively.