Data extracted from previously published studies suggest that asymptomatic osteonecrosis has a high prevalence of progression to symptomatic disease and femoral head collapse. While small, medially located lesions have a low rate of progression, the natural history of asymptomatic medium-sized, and especially large, osteonecrotic lesions is progression in a substantial number of patients. For this reason, it may be beneficial to consider joint-preserving surgical treatment in asymptomatic patients with a medium-sized or large, and/or laterally located, lesion.

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

New technology using magnetic resonance imaging (MRI) allows the surgeon to place total knee replacement components into each patient's pre-arthritic natural alignment. This study evaluated the initial intraoperative experience using this technique. Twenty-one patients had a sagittal MRI of their arthritic knee to determine component placement for a total knee replacement. Cutting guides were machined to control all intraoperative cuts. Intra-operative events were recorded and these knees were compared to a matching cohort of the senior surgeon's previous 30 conventional total knee replacements. Post-operative scanograms were obtained from each patient and coronal alignment was compared to previous studies using conventional and computer-assisted techniques. There were no intra-operative or acute postoperative complications. There were no differences in blood loss and there was a mean decrease in operative time of 14% compared to a cohort of patients with conventional knee replacements. The average deviation from the mechanical axis was 1.2°of varus, which was comparable to previously reported conventional and computer-assisted techniques. Custom-fit total knee replacement appeared to be a safe procedure for uncomplicated cases of osteoarthritis.

The primary goals of this critical literature review were to determine whether revision rates of primary total hip arthroplasty in patients with osteonecrosis differ based on the underlying associated risk factors and diagnoses, whether the outcomes of this procedure have improved over the past two decades, and to compare outcomes based on study level of evidence. A systematic literature review yielded 67 reports representing 3,277 hips in 2,593 patients who had a total hip arthroplasty for osteonecrosis of the femoral head. Stratification of outcomes by associated risk factors or diagnoses revealed significantly lower revision rates in patients with idiopathic disease, systemic lupus erythematosus, and after heart transplant, and significantly higher rates in patients with sickle cell disease, Gaucher disease, or after renal failure and/or transplant. There was a significant decrease in revision rates between patients operated upon before 1990 versus those in 1990 or later, with rates of 17% and 3%, respectively. The results for arthroplasties performed in 1990 or later were similar to those for all hips in publicly reported national joint registries. Certain risk factors were associated with higher revision rates in patients with osteonecrosis who were treated by total hip arthroplasty. However, most patients (82%) do not have these associated negative risk factors. Overall, this critical literature review provides evidence that osteonecrosis itself, or when associated with the most common risk factors and/or diagnoses, is not associated with poor outcomes in total hip arthroplasty.

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