Twenty-two high-density polyethylene sockets from Charnley low-friction arthroplasties have been studied. Acrylic casts and shadowgraph techniques were used to measure both the real and radiographic rates of wear; these rates showed a significant correlation. In the sagittal plane, nine of the sockets had worn lateral to a line drawn vertically from the centre of curvature of the socket, 12 had worn medial to that line and only one was worn exactly in the line. In the coronal plane, nine sockets had worn in front of a similar vertical line, two behind that line and 11 had worn exactly in the line. Evidence of impingement of the neck of the stem onto the rim of the socket was found in 14 patients; this is considered to be one of the causes of socket loosening. The obvious solution is to reduce the diameter of the neck of the stem from 12.5 mm to 10 mm; provided that it is made of cold-formed, high nitrogen-content stainless steel, this narrower neck is strong enough not to fracture.
It is probable that both genetic and environmental
factors play some part in the aetiology of most cases of degenerative
hip disease. Geneticists have identified some single gene disorders
of the hip, but have had difficulty in identifying the genetics
of many of the common causes of degenerative hip disease. The heterogeneity
of the phenotypes studied is part of the problem. A detailed classification
of phenotypes is proposed. This study is based on careful documentation
of 2003 consecutive total hip replacements performed by a single
surgeon between 1972 and 2000. The concept that developmental problems
may initiate degenerative hip disease is supported. The influences
of gender, age and body mass index are outlined. Biomechanical explanations
for some of the radiological appearances encountered are suggested.
The body weight lever, which is larger than the abductor lever, causes
the abductor power to be more important than body weight. The possibility
that a deficiency in joint lubrication is a cause of degenerative
hip disease is discussed. Identifying the phenotypes may help geneticists
to identify genes responsible for degenerative hip disease, and
eventually lead to a definitive classification.
We report the long-term radiological results of 58 total hip arthroplasties (THA) using the Charnley offset-bore acetabular
In laboratory tests, the ultra-high molecular weight polyethylene used for the acetabular cups of Charnley hip prostheses has a very low wear rate against steel. In the body radiographic measurements indicate that the polyethylene wears more rapidly. In order to investigate this higher wear rate, the sockets of acetabular cups removed at post-mortem have been examined using optical and electron microscopy. It has been shown that a
In the 1990s, a bioactive bone cement (BABC) containing apatite-wollastonite glass-ceramic (AW-GC) powder and bisphenol-a-glycidyl methacrylate resin was developed at our hospital. In 1996, we used BABC to fix the acetabular component in primary total hip arthroplasty (THA) in 20 patients as part of a clinical trial. The purpose of this study was to investigate the long-term results of primary THA using BABC. A total of 20 patients (three men and 17 women) with a mean age of 57.4 years (40 to 71), a mean body weight of 52.3 kg (39 to 64), and a mean body mass index (BMI) of 23.0 kg/m2 (19.8 to 28.6) were evaluated clinically and radiologically. Survival analyses were undertaken, and wear analyses were carried out using a computer-aided method.Aims
Patients and Methods