A decrease of 15% in femoral off-set (FO) was reported to generate a weakness of the abductor muscle after THA, which may increase the risk of limping and dislocation. However, this value was defined under experimental conditions using a CYBEX machine, which does not correspond to daily life activities. To our best knowledge, there is no reported study about the effect of the FO alteration on the gait, following THA. To assess the functional consequences of an alteration in the FO, a prospective comparative study was carried out and it included patients who underwent THA for primary osteoarthritis. In order to select only patients with an isolated FO alteration, the three-dimensional hip anatomy was analysed preoperatively and post-operatively with CT-scans using HipPlan Software. Three groups were defined according to the FO alteration: 15% decrease, restored and 15% increase. The exclusion criteria were: the presence of an arthroplasty or of an associated pathology on the contra-lateral or the same limb, a spine disease and a non-restoration of the other hip parameters (center of rotation, limb length). 26 patients were included: 12 restored, 9 decreased FO and 5 increased FO. The patients were composed of 20 women and 6 men with an average age of 67.7 ± 9 years. All the patients were assessed clinically, pre-operatively and 1 year after surgery with 4 scores: the Poste Merle d'Aubigné score, the Harris score, the womac score and the quality of life score SF12. A gait analysis was performed at 1 year follow-up using an ambulatory device (Physilog (3)) under normal walking conditions. The patients were asked to walk at their usual normal speed for 30 metres in a standardized corridor: Each limb was compared to the contra-lateral healthy limb.Introduction
Materials and Methods
