PubMed · 4593373
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D W Parsons. 1972. Total hip replacement.. https://pubmed.ncbi.nlm.nih.gov/4593373/
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The development of malignant lesions in the acetabulum can lead to painful and disabling bone destruction. In carefully selected patients where the cortical still provides a sufficient barrier protecting the joint, percutaneous injection of ciment (10-15 cc) can be a successful mean of countering both pain and functional impairment. This easy-to-perform technique requires only local anaesthesia and can be highly cost-effective. The antalgic effect is rapid. Most patients are able to walk again within 1 to 5 days (an effect which is particularly spectacular in bedridden subjects) probably due to the reduced pain and to better distribution of the mechanical forces. Hospitalization is usually shortened. In our experience with 18 patients, clinical improvement has been maintained for up to 18 months (mean follow-up 7 months) if the osteolytic process remains under control. Secondary effects are not rare but usually temporary. Recurrent pain, fever and/or inflammatory processes have been observed and usually resolve within 1 to 4 days. Intra-articular leakage can be avoided by careful patient selection. In association with radiotherapy, percutaneous injection of ciment appears to be an useful alternative to surgery for patients with destructive malignant lesions of the acetabulum, particularly in those with a poor clinical status and a short life expectancy. This technique has already been shown to be effective in lesions of the vertebral bodies. Several teams have made further attempts in other localizations.
The mechanisms of wear in ultra-high-molecular-weight polyethylene (UHMWPE) acetabular cups were investigated on both laboratory simulator-tested cups and a clinically retrieved component. Two different levels of wear process were identified: one characterized by the formation and detachment of platelet-like flakes from initial machining marks, and the other by the formation of fine ripple and fibrils by repeated passes of microscopic asperities on the femoral head. Both wear processes could be described by a criterion of critical plastic strain. A theoretical model was developed to account for the generation of the microscopic wear particles based on such a critical strain criterion. Its predictions of the dependence of the UHMWPE wear rate on surface roughness and applied load were in excellent agreement with previously published experimental correlations.
Physeal distraction was applied with an external fixator to the triradiate cartilage of dogs with the aim of increasing the capacity of the acetabulum. The force was continued for from 2 to 6 weeks and the consequent changes were evaluated with regard to function and structure by radiography and microscopy. The distraction, without producing epiphysiolysis and destruction of the cartilage, resulted in expansion of the pelvic bones. The depth and volume of the acetabulum were increased, but the acetabular angle was decreased. Distraction also caused proliferation of the lacunar cells and the number of mammillary processes in the cartilage columns increased. Distraction can therefore be applied to the triradiate cartilage to enlarge the capacity of the acetabulum without producing epiphysiolysis.