Service d'Orthopédie de:
Hôpital Maisonneuve-Rosemont
Service d'orthopédie
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- Écrit par maxime
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- Affichages : 4448
Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty
Background. Primary total hip arthroplasty leads to better functional capacities but a general weakness of abductor muscles often persists. A larger head component may improve the postural balance in the medial–lateral direction. The aims of this study are (1) to compare postural stability in patients after total hip and surface replacement arthroplasties and (2) to evaluate the effect of the biomechanical reconstruction on postural stability. Methods. Six months post-surgery, three groups of ten subjects (total hip and surface replacement arthroplasties and control) performed quiet standing tasks in both dual and one leg stance and a hip abductor muscles strength test. The root-mean-square amplitude of centre of pressure and centre of mass displacement in the anterior–posterior and medial–lateral directions were calculated for dual stance task. Findings. Statistical analyses showed greater centre of pressure and centre of mass displacement amplitude in the medial–lateral direction during the dual stance for the total hip arthroplasty compared to the surface replacement and control subjects (P < 0.05). All control subjects completed the one leg stance compared to nine in the surface replacement and five in the total hip arthroplasty group. No statistical difference was found between the groups in the hip abductor muscles strength. Interpretation. The better anatomical preservation, absence of femoral stem and the larger bearing component could account for the return to better postural stability in surface replacement patients in comparison to total hip patients. Further studies are needed to determine the impact of each of these factors on the postural balance.
© 2007 Elsevier Ltd. All rights reserved.
Keywords: Postural control; Postural balance; Postural mechanism; Surface replacement arthroplasty; Total hip arthroplasty; Muscular strength; Femoral offset
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- Écrit par maxime
- Catégorie : Non catégorisé
- Affichages : 2620
Femoral Component Positioning in Hip Resurfacing With and Without Navigation
Abstract Early failures after hip resurfacing often are the result of technical errors in placing the femoral component. We asked whether image-free computer navigation decreased the number of outliers compared with the conventional nonnavigated technique. We retrospectively compared 51 consecutive hip resurfacings performed using image-free computer navigation with 88 consecutive hip resurfacings performed without navigation. Patient demographics were similar. There were no differences in the average native femoral neck-shaft angles, planned stemshaft angles, or postoperative stem-shaft angles. However, when the postoperative stem-shaft angle was compared with the planned stem-shaft angle, there were 33 patients (38%) in the nonnavigated group with a deviation greater than 5 in contrast to none in the navigated group. Notching was present in four patients in the nonnavigated group and none in the navigated group. The average operative time was 111 minutes for the navigated group and 105 minutes for the nonnavigated group. Image-free navigation decreased the number of patients with potentially undesirable implant placements.
Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
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- Écrit par maxime
- Catégorie : Non catégorisé
- Affichages : 4080
Chromium and cobalt ion release following the Durom high carbon content, forged metal-on-metal surface replacement of the hip
We evaluated the concentrations of chromium and cobalt ions in blood after metal-on-metal surface replacement arthroplasty using a wrought-forged, high carbon content chromiumcobalt alloy implant in 64 patients. At one year, mean whole blood ion levels were 1.61 ?g/L (0.4 to 5.5) for chromium and 0.67 ?g/L (0.23 to 2.09) for cobalt. The pre-operative ion levels, component size, female gender and the inclination of the acetabular component were inversely proportional to the values of chromium and/or cobalt ions at one year postoperatively. Other factors, such as age and level of activity, did not correlate with the levels of metal ions. We found that the levels of the ions in the serum were 1.39 and 1.37 times higher for chromium and cobalt respectively than those in the whole blood. The levels of metal ions obtained may be specific to the hip resurfacing implant and reflect its manufacturing process.
Traduction Française indisponible.
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- Écrit par maxime
- Catégorie : Non catégorisé
- Affichages : 3434
Comparison of alumina-alumina to metal-polyethylene bearing surfaces in THA : A randomized study with 4- to 9years follow-up
We report the clinical and radiological results of 140 primary THAs, randomized to receive metalpolyethylene or alumina-alumina bearing surfaces. At last follow-up (average 79 months), no significant difference was found on clinical scores (WOMAC and Merle D’Aubigné) between the two groups. However, linear wear of 1 mm or more of the liner was observed in 89% (50/56) of polyethylene cases, whereas no measurable wear was noted in the alumina- on-alumina group. Calcar resorption was noted in 34% (19/56) of cases in the polyethylene group versus 6% (3/51) in the alumina group. Although no aseptic loosening was present in either group, 2 hips in the polyethylene group underwent revision for severe liner wear, and 2 more are pending. No specific complication was associated with alumina components. This study is in line with other reports indicating that alumina-alumina bearing surfaces have better wear properties than metalon standard polyethylene and should be considered for THA in young and active patients. Keywords : arthroplasty ; hip ; alumina ceramic ; polyethylene ; wear ; randomized.
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