Lateral tibiofemoral compartment narrowing after medial unicondylar arthroplasty.

UNLABELLED: Many surgeons have sought to avoid valgus postoperative limb alignment when performing medial unicondylar arthroplasty under concern that such posture accelerates lateral tibiofemoral compartment joint space narrowing. To test whether postoperative limb alignment was associated with lateral compartment narrowing, we measured the lateral compartment joint space width from the most recent single-leg erect anteroposterior radiograph and similarly-obtained early postoperative radiographs of 113 medial unicompartmental arthroplasties (eight designs, 91 patients) that had a minimum of 10 years (range 10-19 years) clinical followup. The mean (+/- standard deviation) narrowing was 0.03 +/- 0.13 mm per year (< 0.10 mm per year, 89 knees) or 7% +/- 30% (< 25%, 90 knees). Narrowing increased with more valgus (less varus) of the early postoperative hip-knee-ankle angle. However, the effect of alignment was small (narrowing increased by 0.01 mm per year per each 1 degree) and it was not linked with an outcome of 25% or greater, 50% or greater, or 75% or greater narrowing. In summary, narrowing increased slightly with more valgus (less varus) early postoperative limb alignment, but limb alignment was a poor predictor of which knees would develop more complete joint space thinning. LEVEL OF EVIDENCE: Level IV, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Impaction allografting for massive femoral defects in revision hip arthroplasty using collared textured stems.

We present a prospective study of impaction grafting using collared textured stems in femurs with massive defects (defined as requiring >150 cm(3) of cancellous allograft). Eighteen hips were followed for a minimum of 2 years. Average Harris hip scores increased from 50 preoperatively to 83 at most recent follow-up. Seventeen hips were functioning well at the time of most recent follow-up and exhibited no stem subsidence or aseptic loosening. One hip was associated with visible subsidence and required further revision. Single-photon emission computed tomography analyses performed at an average of 37 months indicated active graft reorganization in all cases studied. Impaction allografting with collared textured stems for massive defects demonstrates good intermediate-term clinical results and may be a useful alternative to allograft stem composites and megaprostheses.

Hemoglobin substitutes.

Orthopaedic patients frequently require blood transfusions to treat peri-operative anemia. Research in the area of hemoglobin substitutes has been of great interest since it holds the promise of reducing the reliance on allogeneic blood transfusions. The three categories of hemoglobin substitutes are (1) cell-free, extracellular hemoglobin preparations made from human or bovine hemoglobin (hemoglobin-based oxygen carriers or HBOCs); (2) fluorine-substituted linear or cyclic carbon chains with a high oxygen-carrying capacity (perfluorocarbons); and (3) liposome-encapsulated hemoglobin. Of the three, HBOCs have been the most extensively studied and tested in preclinical and clinical trials that have shown success in diminishing the number of blood transfusions as well as an overall favorable side-effect profile. This has been demonstrated in vascular, cardiothoracic, and orthopaedic patients. HBOC-201, which is a preparation of cell-free bovine hemoglobin, has been approved for clinical use in South Africa. These products may well become an important tool for physicians treating peri-operative anemia in orthopaedic patients.