We undertook a review of the literature relating to the two basic stem designs in use in cemented hip replacement, namely loaded tapers or force-closed femoral stems, and the composite beam or shape-closed designs. The associated stem fixation theory as understood from in vitro studies and finite element modelling were examined with reference to the survivorship results for each of the concepts of fixation. It is clear that both design principles are capable of producing successful long-term results, providing that their specific requirements of stem metallurgy, shape and surface finish, preparation of the bone and handling of the cement are observed.
One hundred forty-nine medial prostheses were implanted in 140 patients between 1988 and 1996. After a mean of 67 months 28 patients had died, without the need for revision. Seventeen prostheses were lost to follow-up. Revision surgery using a total knee prosthesis was performed in 16 cases. In four others, a lateral prosthesis was implanted subsequently to a medial one. One of these four was revised to a total knee prosthesis 6 years later. In another four cases, late complications of the meniscal bearing were treated with replacement of this bearing. The surviving prostheses were seen back after a mean of 126 months. The cumulative survival rate at 10 years was 82% for the whole population and 84% when knees with a previous high tibial osteotomy were excluded. Since these results compare poorly to the survival of total knee arthroplasty, this prosthesis is not the first-choice implant. Because it preserves a maximum of bone stock and is revised to a total prosthesis almost without difficulty, it is the first-choice implant for medial unicompartmental osteoarthritis in patients younger than 65. Further research is mandatory to confirm that this prosthesis very rarely needs revision in patients older than 75. It should not be used in osteotomized knees.
Nine elderly patients were treated by salvage hip arthroplasty following failed internal fixation of an intertrochanteric or subtrochanteric hip fracture. The mean age at time of fracture was 79 years (range 67-94 years). The mean interval from initial fracture fixation to conversion arthroplasty was 7 months (range 5 days to 19 months). One 84-year-old patient died 6 weeks postoperatively from a pulmonary infection. The remaining eight patients were assessed clinically and roentgenographically after a mean follow-up period of 41 months (range 4-85 months). The functional results, rated according to the Merle d'Aubigné hip rating scale, were excellent in one patient, very good in four patients, good in two patients, and fair in one patient. Serial roentgenographic analysis showed new bone formation around the extramedullary part of the femoral component in all these patients and bone remodelling of the diaphyseal part of the femur in all patients. The preservation of the functional continuity of the abduction apparatus during surgery and the early walking with full unrestricted weight-bearing made possible by the arthroplasty are considered to be the major contributing factors to these results.
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