INTRODUCTION. Cadaveric studies have reported damage to the direct head of rectus femoris and tensor fascia lata muscles with direct anterior approach(DAA) and to the abductors, external rotators with posterior approach(PA). The aim of this prospective study was to evaluate differences in hip muscle strength recovery between DAA and posterior approach (PA) THA. METHODS. Patients with unilateral hip osteoarthritis undergoing THA at a single institution from January 2011 to October 2011 were enrolled. All DAA THA's were performed by one surgeon, and all PA THA's were performed by another surgeon with similar design of components, pain management and rehabilitation protocols. Hip muscle strength was measured with a handheld dynamometer in all planes by a single observer preoperatively, at 6 weeks, 3 months and 6 months. Functional recovery was assessed with the motor component of Functional Independence Measure, UCLA activity score, Harris hip score, SF-12 score. RESULTS. There were 30 patients (15 per group) with similar age, sex, BMI and preoperative functional scores. There was a significant difference between groups in ER strength recovery pattern(p=0.04) with greater mean deficit in PA group from preoperative to 6 weeks(37%), 3 months (28%) and 6 months (25%); whereas DAA group demonstrated 3% mean deficit at 6 weeks, 2% mean improvement at 3 months and 10% mean improvement at 6 months from preoperative values. Flexion strength decreased in DAA group by a mean of 10% at 6 weeks(p=0.07) but improved at 3 months by a mean of 12% as compared to preoperative values. There were no differences in recovery pattern of other hip movements between groups. Functional recovery scores between groups were similar. DISCUSSION. Both DAA and PA THA offer similar recovery in hip muscle strength up to 6 months with exceptions of ER strength deficit in PA group and a trend to flexion strength deficit at 6 weeks in DAA group

Purpose. Investigating the effects of femoral stem length on hip and knee muscle strength. Methods. The study included 20 patients having undergone total knee prostheses (TKP) due to coxarthrosis and 10 healthy subjects. Of the 20 patients, 10 underwent conventional TKP and 10 had Thrust Plate Prothesis (TPP). For the assessment of the patients’ muscle strength of operated and non-operated hips (Gl. medius and Gl. Maximus) and knees (Quadriceps Femoris-QF), the Hand-Held Dynamometer (HHD) was used. Results. A significant difference was observed in the muscle strength of Gl. medius in TPP patients and of Gl. maksimus in conventional TKP patients (p <0.05). Compared to the healthy group, only hip muscle strength decreased in TPP patients, but both hip and knee muscle strengths decreased in conventional TKP patients (p <0.05). Conclusion. A decrease in hip and knee muscle strengths was determined in the TPP and conventional THA patients, compared to healthy subjects. Compared to the bone protective prosthetic systems (eg TPP), a significant difference is observed in the QF muscle strength in intramedullary prosthesis applications. This data may be used in planning the treatment of patients with hip arthroplasty