| Objective: This study aims to compare the outcome between an alumina ceramic- on-ceramic (COC) articulation with a metal on high-molecular-weight polyethylene articulation (MOP) at the intermediate term. To analysis the clinical outcome of two articulation couples , providing the reference to selective for cementless THA.Methods: Between May 1995 and november 2005, 82 MOP and COC total hip arthroplasties in 79 patients were retrospectively reviewed. According to the age and activity , the patients were divided to two groups. In the young(<50 years), active patient population(A group), 18 patients (20 hips) received a MOP bearing, There were 7 males and 11 females . Their age was 48.06±8.98 years, and body mass index was 24.17±1.30 kg/m2 . 21patients (22 hips) received a COC bearings,. Their age was 39.52±7.41 years with 12 males and 9 females, and body mass index was 23.38±1.71 kg/m2 . In the old(≥50 years), nonactive patient population(B group), 19 hips in 19 patients with mean age 63.05±3.52 each received a MOP bearing. There were 8 males and 11 females , and body mass index was 23.71±1.51 kg/m2 . 21 patients (21 hips) received a MOP bearing, There were 7 males and 14 females . Their age was 59.43±5.28 years, and body mass index was 23.67±1.16 kg/m2 . The patients with MOP bearings received the AML and H-G femoral stem, and others with COC bearings received the F2L and C2 femoral stem. We assessed the clinical and radiographic results of patients treated by MOP and COC total hip arthroplasty at the intermediate term, Patients were clinically evaluated using the Harris Hip Score. investigating implant related failure, complication rate, and occurrence of bearing wear and wear-associated osteolysis. Kaplan—Meier analysis was performed to evaluate the survival of the component.End point was radiographical loosening or revision of the component for any reason .Results:At least follow-up of 5 years, in the A group ,3 hips with COC bearing have undergone revision of both components for loosening associated osteolysis.and others is OK. No fracture, No infections, or DVT. No ceramic fracture occurred.Clinical results: In the A group , The average preoperative Harris Hip Score of the patients with COC bearing was 36.81±5.66 points, which improved to 94.52±1.91 points at the 6 months and 93.33±2.63 points at the 7.7 years postoperatively. Preoperative Harris Hip Score of the patients with MOP bearing was 37.11±5.26 points, which improved to 94.33±1.88 points at the 6 months and 83.39±8.73 at the 7.8 years postoperatively. The difference of Harris Hip Score between the COC and MOP bearing was no significant in preoperatively(P=0.982)and 6 months postoperatively(P=0.756) . The Harris Hip Score were significant differences in 7.7(7.8) years postoperatively (P=0.000). In the B group , The average preoperative Harris Hip Score of the patients with COC bearing was 37.00±4.98 points, which improved to 93.00±2.07 points at the 6 months and 91.81±2.82 points at the 7.4 years postoperatively. Preoperative Harris Hip Score of the patients with MOP bearing was 36.58±5.12 points, which improved to 93.05±1.47 points at the 6 months and 90.16±3.11 at the 7.5 years postoperatively. The difference of Harris Hip Score between the COC and MOP bearing was no significant in preoperatively(P=0.725), 6 months postoperatively(P=0.927) and 7.4(7.5) years postoperatively(P=0.782) .In the B group ,two patients reported the incidences of noise described as clicking.but there was nothing about Clinic and Radiography.Radiographic results: In the A group , no loosening occurred in the COC bearing, and no more than 3 mm subsidence of the feromal component. 2 feromal stems was in varus, and has more than 3 mm subsidence, and 3 acetabular components were loosening. In the B group , there was no loosening.Both of A and B groups ,there was no direct measured wear in the COC bearing; Wear was identified in all MOP replacement. Mean wear with the MOP bearing was 0.29±0.24 mm/y in the A group and 0.15±0.13 mm/yr in the B group. There were significant differences about the wear in the COC and MOP bearing (P <0.005). In the A group , osteolysis was identified in all MOP replacement; 27.3% have osteolysis in the COC bearing . In the B group , 23.8% have osteolysis in the COC bearing and in the MOP replacement it is 63.16% .In the 2 groups Osteolysis in the COC bearing significantly less than in the MOP bearing(P <0.005).Conclusion:1. With excellent outcome at the intermediate term , less revisions for aseptic loosening ,wear and minimal cortical erosions, alumina ceramic-on-ceramic (COC) articulation couples are performing in a manner superior to the metal on high- molecular-weight polyethylene bearing (MOP) in this young(<50 years), active patient population. Total hip arthroplasty using COC implants that have excellent wear resistance,decreased particulate debris and the ability to function at a high level for a long time is a safe and reliable procedure in the comparably young and active patient. However it was restrained by the expensive price, and the long-term results still need further follow-up.2. In the old(≥50 years), nonactive patient population, other than significantly greater wear and cortical erosions in the MOP, there was no significant difference in midterm outcome between the MOP and COC.So we should choose the cheap implant for them. |
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