Objective To study the effect of the high molecular weight polyethylene on the periprosthetic tissue in vivo as to give some reference to treatment of loosening hip arthroplasty. Methods Every lower limb of 20 New Zealand white rabbits was implanted a CoCrMo plug in femur by intercondylar notch. 15 mg polyethylene particles, dispersed in 1.5 ml normal saline solution, were injected into one knee joint. The other knee joint was injected 1.5 ml normal saline solution as control. This procedure was repeated 2,4,6,8 and 10 weeks after the implantation. Both of two lower limbs were given a X-ray examination 10 weeks to assess if there were periprosthetic osteolysis and loosening of the plugs. All animals were killed 2 weeks afer the last injection. The distribution of polyethylene in the knee joint capsule was examined to understand if there were loosening of implants or tissue change around implants. Knee joint capsule tissues and periprosthetic tissues were examed by optical microscope. Results Nine cases formed fibrous membrane and four cases formed new bone around prostheses in experiment group. Eleven cases formed new bone and two cases formed fibrous membrane in control group(Plt;0.05)The X-ray results indicated that the plugs were in distal medulla of femur. There was no sign of priprosthetic osteolysis, implants loosening or new bone formation. Optical microscope study indicated that there were a lot of polyethylene particles inside the capsule. The polythlene particles were surrounded by multinucleated foreignbody giant cells and fibrobast. In some cases, there were fibroblasts and fibrous tissue around plug. There were no polyethylene paticles and multinucleated foreignbody giant cells around plug in the marrow. There were alot of polyehtlene particles on the joint surface. The bone surface that contacted multinucleated foreignbody giant cells was coarse. Conclusion Maximing ultra high molecular weight polyethylene can restrain rabbit periprosthetic bone formation
Objective To evaluate the clinical valueof the revision of total hip replacement(THR), to analyse the reason of the rev isions, and to discuss the main difficulties and measures to manage it.Methods From June 1998 to January 2002, 15 cases (15 hips) were revised on totalhip replacement. The reasons for revision in the cases were as follows:failure of primary operative techenique, loosening and sinking of the components, displacement of the prosthesis, erosion of the acetabulum, as well as fracture of the femoral stem. The main difficulties of the revision were:poor health condition of the patients; the remove of the prosthesis of the primary THR,especially the broken femoral stem and the cements; the loss of localbone. The measures to remove the broken femoral stem were described.ResultsAll cases were followed up 2.4 years on average: 2 patients died from heart disease and cerebrovascular disease respectively, while the good results were achieved in the others.No infection, dislocation, loosening, and other complications occurred. The good effects were related with following factors:mild degree of illness; no severe bone defect; most of the first femoral head replacement.Conclusion The revision of THRis a more difficult operation, so that the special instrument and equipment andoperative experience are required.
Objective To discuss the clinical application of preserving femoral neck in total hip arthroplasty and to analyze the early stage results.Methods From January 1999 to June 2001, 12 patients underwent total hip arthroplasty with preservation of femoral neck. We cut off the femoral head in infra-head position with improved Moore micro-incisions to reserve intact neck of femur. Thensuitable size of extra cup was selected and placed at 55° eversion angle. The internal cup, made from ultra high polymer poly thene and with ultra radius design, was placed at 45°eversion angle. Harris scores were recorded before operation, after operation and during the follow-up. During the follow-up, the X-rayfilms were taken to assess position, loosening of the prosthesis and ectopic ossification.Results All 12 patients were followed up 2-4.5years with an average of 3.1 years. The mean Harris score of hip elevated from 54 scores before operation to 92 scores of the last follow-up. Mild ectopic ossification occurred in 3 cases. There was no prosthesis loosening and femoral prosthesis setting, and only onepatient had mild bone absorption around femoral prosthesis.Conclusion Total hip arthroplasty with femoral neck preservation is a good option for the patients who need total hip arthroplasty for variable reasons, which is indicated for the patients whose femoral neck is intact with no osteoporosis.
ObjectiveTo investigate the clinical outcome of application of joint prosthesis in limb salvage treatment of mildmalignant tumor at the articular ends of femurs, with severe osteolysis. Methods The treatment of 15 cases of mildmalignant tumor at the articular ends of femurs with severe bone destruction, from 1978 to 1999, was reviewed. There were 10 cases of giant-cell bone tumor and 5 cases of chondrosarcoma, among which there were 5 cases at the stage ofⅠA, 9 cases at ⅠB, and 1 case at ⅡA, with 4 cases at the proximal end and 11cases at the distal end. The tumor was totally removed, with a massive bone defect left at the foci, and then the prosthesis replacement was performed to reconstruct the articular joint. All of the 15 patients were followed up for 9 monthsto 20 years, 4 years and 3 months on average, before clinical evaluation. Results All of the wound healed well, with primary healing. Local relapse occurred in one case and the patient died of lung metastasis; the amputation of the replaced knee joint was performed in one case due to severe infection after trauma; radiograph showed there was slight sunk of the prosthesis in 2 cases after replacement. The other 11 cases recovered well with satisfactory function. Conclusion The limb salvage treatment of mildmalignant tumor at the articular ends of femurswould be available, especially for those with massive bone destruction, when the tumor is removed by whole and rationally marginal resection, followed by properlyutilization of prosthesis and general post-operative exercise.