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At least 559 records · Page 31Linked to original sources
PubMed1999

An electromyographic study of the hip abductor muscles as subjects with a hip prosthesis walked with different methods of using a cane and carrying a load.

BACKGROUND AND PURPOSE: Certain methods of carrying handheld loads or using a cane can reduce the demands placed on the hip abductor (HA) muscles and the loads on the underlying prosthetic hip. In certain conditions, unusually large forces from the HA muscles may contribute to premature loosening of a prosthetic hip. The purpose of this study was to examine HA use by measuring the amplitude of the electromyographic (EMG) signal from the HA muscles as subjects carried a load and simultaneously used a cane. SUBJECTS: Twenty-four active subjects (mean age = 63.3 years, SD = 10.7, range = 40-86) with a unilateral prosthetic hip were tested. METHODS: The HA muscle surface EMG activity was analyzed as subjects carried loads weighing 5%, 10%, or 15% of body weight held by either their contralateral or ipsilateral arm relative to their prosthetic hip. They simultaneously used a cane with their free hand. RESULTS: The contralateral cane and ipsilateral load conditions produced HA muscle EMG activity that was approximately 40% less than the EMG activity produced while walking without carrying a load or using a cane. CONCLUSION AND DISCUSSION: People who are in danger of premature loosening of their prosthetic hip should, if possible, avoid carrying loads. If a load must be carried, however, then the contralateral cane and ipsilateral load condition appears to minimize the loads placed on the prosthetic hip due to HA muscle activity.

Adult↗
PubMed1998

[Posterior position of acetabular component of a total hip prosthesis: possible cause of lower limb rotation problem].

INTRODUCTION: The authors report the case of an internal rotation of the lower limb, lately ascribed to a posterior placement of the acetabular component during total hip arthroplasty. MATERIAL AND METHOD: A 58 years old female had an irreducible internal rotation of the right hip 3 years after total hip arthroplasty for arthritis. When the hip was extended, the lower limb showed an irreducible internal rotation of 45 degrees. In flexion of the hip this rotation disappeared. AP radiograms showed femur and femoral stem in internal rotation, a healed fracture of the acetabulum, and the acetabular component seemed to be in correct position. On CT scan the acetabular component was 4 cm posterior to the anatomic location, although there was no abnormal anteversion of the stem and acetabular component. Revision, with relocation of the acetabular component, corrected lower limb rotation. DISCUSSION: Posterior position of the acetabular component has not been described as a cause of lower limb malrotation. Normally the strength of the external hip rotators muscles is three times as important as of the internal rotators. The transverse acetabular fracture led to backwards placement of the acetabular component and yelded in an automatic internal rotation of the femur, because the trochanter kept an anatomical position in the horizontal plane. The posteriorised rotation center of the hip had changed the balance of the different rotator muscles, some of them, originally external rotators, becoming internal rotators.

Acetabulum↗
PubMed1996

[Total hip prosthesis for chronic juvenile arthritis. A review of a series of 34 prosthesis].

PURPOSE OF THE STUDY: The purpose of this study was to analyse the results of total hip arthroplasty for chronic juvenile arthritis in order to evaluate risks, problems and benefits of this procedure. MATERIAL AND METHODS: Between 1984 and 1992, 34 total hip prostheses were implanted for chronic juvenile arthritis in 20 patients. Most prosthesis were Zweymuller cementless prosthesis. Mean follow up was 5 years. RESULTS: Results were good. In 85 per cent of cases, patients had a normal activity recovery. Pain relief was very good since in 80 per cent cases patients had a total indolence. DISCUSSION: Beyond these good clinical results at this mean follow-up, the main interest of this study is to characterize two different periods in the surgical technique. The first period when cemented prosthesis was employed and the second one when cementless femoral implants with screwed acetabular component were used. Cementless prostheses appear to be a satisfying solution in this disease, preserving bones and showing very good radiological and functional results. CONCLUSION: Furthermore, the very low complication rate despite general discomfort may prompt us to use total hip arthroplasty for the treatment of chronic juvenile arthritis.

Adolescent↗
PubMed2000

[Experimental in vitro investigations of hardness changes in hip prosthesis polyethylene cups caused by x-rays and aging].

The aim of this paper was to determine the influence of X-rays and ageing on the mechanical properties of polyethylene cups of Weller type hip prostheses. Polyethylene cups produced in the period between 1987 and 1992 were investigated. Some of the cups were exposed to a radiation dose exceeding greatly the average dose used in a routine X-ray examination. Polyethylene cups produced in different years and those subjected to "artificial ageing" (long-term exposure to high temperature) were examined. Brinell's method was used to assess the hardness of polyethylene. The results of this study indicate that both exposure to X-rays and ageing lead to hardening of the cups. This may in turn cause cup fractures--a potential source of complications following hip replacement procedures.

Equipment Failure Analysis↗
PubMed1983

A canine cementless total hip prosthesis model.

To evaluate a porous fiber titanium composite as a fixation method, total hip arthroplasty was performed in 13 large male mongrel dogs. In seven both acetabular and femoral composites were fixed with a porous titanium fiber composite, and in the other six the acetabulum was fixed with acrylic cement. The animals were killed one, three, and six months following implantation. At autopsy all components were fixed by bony ingrowth. There was progressive remodeling of the ingrown bone and of the bone trabeculae surrounding the prosthesis in the three- and six-month animals, with gradual thickening and development of haversian structures. Cortical osteoporosis, which did not appear to be progressive, was detected in both the one- and six-month specimens.

Acetabulum↗