Hybrid metal-on-metal hip surface arthroplasty in 18 cases: 2 -year follow-up study / 中国组织工程研究

ABSTRACT

BACKGROUND: Metal-on-metal hip surface arthroplasty has improved the abradability for hip joint prosthesis and has the characteristics of normal biological stress transfer.OBJECTIVE: To observe the long-term state of hip-joint function of patients who underwent metal-on-metal hip surface arthroplasty.DESIGN: Follow-up study for cases.SETTING: Department of Orthopaedics, Jiangsu Provincial Corps Hospital of the Chinese People's Armed Police Force; Department of Orthopaedics, Affiliated Hospital of Nantong University.PARTICIPANTS: Eighteen cases (23 hips) who underwent a metal-on-metal hip surface arthroplastyprocedure in the Department of Orthopaedics, Jiangsu Provincial Corps Hospital of the Chinese People's Armed Police Force, and Department of Orthopaedics, Affiliated Hospital of Nantong University between September 2004 and July 2005 were recruited in this study. All cases, aged 28 to 54 years, include 11 males and 7 females. According to the classification of etiology, there were 13 cases of osteonecrosis(16 hips),3 cases of osteoarthritis( 4 hips ),1 case of congenital hip dysplasia (2 hips) and 1 case of posterior trauma arthritis(1 hip ). All cases applied the Conserve Plus resurfacing prosthesis (manufactured by Wright Medical Technology, USA), of which the pattern number of acetabular cup (press-fit depth 1-2 mm) ranged from 38 mm to 56 mm in the inner diameter and from 44 mm to 62 mm in the outer diameter and that of femoral head cup ranged from 38 mm to 56 mm in the outer diameter. Preoperatively all patients signed the informed consent for the surgery, and the application of this technique also gave the approval of the Ethics Committee of the hospital.METHODS: ①After the epidural and lumbar combination anesthesia was satisfactory, the coxacava was exposed at first and the suitable size acetabular cup coated by hydroxyapatite ceramic was selected to be implanted, to be tightened and to be fixed by press-fit referring to the anatomical position. Subsequently to install the femoral head prosthesis, femoral cup was laid on the ready caput femoris and impacted by the presser to make the metal cup paste close-up with sclerotin when the concocted bone cement was overlaid on the prefabricated caput femoris surface and internal surface of prosthesis. Further, short-term of femoral cup should be kept the conformity with axial ray of the femoral neck. ②Patients were allowed to make the function exercise such as initiative stretch and contract of quadriceps muscle of thigh, passive motion of the knee joint and initiative motion of the knee joint under the non-weight loading on bed. Then they were encouraged to walk with two walking sticks two weeks after operation, progressing to get out of the two walking sticks six weeks postoperatively. All affected extremities were fixated with T-shaped tabula shoes in the abduction position after operation. ③All patients were reviewed with taking the anteroposterior radiographs of pelvis, evaluation of the clinically curative effect on the procedure of metal-on-metal hip surface arthroplasty and biocompatibility between the prosthesis and the host one year and two years after operation. Moreover, Harris score was assessed for all affected hips preoperatively, one year and two years postoperatively.MAIN OUTCOME MEASURES: ①The clinically curative effect on metal on metal hip surface arthroplasty; ②Biocompatibility;③The Harris score for the affected hips; ④The pain status of hip after operation.RESULTS: Eighteen cases were all brought into the outcome analysis at last.①The curative effect on the metal-on-metal hip surface arthroplasty The femoral component of one case had a varus deformation of 10°six weeks after operation, but such complications as component loosening and femoral neck fractures, etc. Did not occur during the coming follow-up. The locations of rest prosthesis were satisfactory. Substantial radiolucencies were found at the rim of acetabular component (1 and 2 zone) in two hips, respectively one and two years after operation. But there was no evidence of radiolucencies around the short-stem of femoral component.②Biocompatibility No patients were found to have obvious reactions including renal toxicity, pyretogen and rejection. No radiograph showed signs of loosening, dislocation, heterotopic bone formation, femoral neck narrowing, femoral head necrosis and prosthesis fixation failure, etc.③Harris score for the affected hips The Harris score of all disease hips was improved from the mean 46 preoperatively to 85 one year after operation to 93 two years postoperatively. Of these,15 hips were excellent(> 90),6 hips good (80-89), and 2 hips fair(70–79).④The pain status of hip after operation Two patients complained of slight pain, one patient of moderate pain, and no cases of severe pain happened.CONCLUSION: The long-term outcome for hip disease patients who undergo metal-on-metal hip surface arthroplasty is satisfactory.