A Comparison Of The Mid-term Results Of Harris-Galante I And Reflection Cementless Acetabular Components

Objective: To analyze the factors affecting the curative effects of cementless acetabular components by making a comparative study of the mid-term clinical and radiographic curative effects of two acetabular prosthesis-Harris-GalanteⅠand Reflection,which respectively represent the first generation and the second generation of acetabular prosthesis.Methods: We retrospectively studied the cases of patients who received total hip arthroplasty in the First Affiliated Hospital of Soochow University: 21 patients (Group A) from 1992 to 2000 with Harris-GalanteⅠcup and 74 patients (Group B) from 2000 to 2005 with Reflection cup.In Group B, according to different polyethylene liners , the group of cases with high density polyethylene was B1(32 patients) and the group of cases with highly cross-linked high density polyethylene was B2 (42 patients ). In Group A, there were 10 men and ten women aged between 32 and 70 years old, whose average age was 56.5. In Group B, there were 34 men and 40 women aged between 25 and 82, whose average age was 58.8. In the preoperative and postoperative period and in our clinical follow-up, hip joint functions were graded with Harris hip score. The postoperative radiographic examinations included measuring the abduction and anteversion angles of the cups and observing the gaps between the acetabular component and the bones. The radiographic examinations in our clinical follow-up included observing the existence of radiolucent lines,the liner wear rate, the migration of the acetabular, and observing the occurrence of osteolysis in surrounding cups.The data of the cases was analyzed with statistical treatment by using the SPSS13.0 software. The preoperative,short-term and mid-term postoperative Harris scores of Group A and Group B, of Group A, Group B1 and Group B2 were respectively compared with each other and the ten-year Kaplan-Meier survival curves of the groups were compared, the end point of observation being osteolysis and revision.Results: Of the 20 cases of follow-up in Group A, the shortest duration was 10 years. Of the 71 cases of mid-term follow-up in Group B, the average duration was 7 years (6-11years), 30 case in B1 Group and 41 cases in B2 Group. Comparing the Harris Hip Score of Group A and Group B, of two groups at random among Group A, Group B1 and Group B2, we found no statistical difference in preoperative and early postoperative periods(P>0.05). In the mid-term results , there was statistical significance in the differences between Group A and Group B, Group A and Group B1, Group A and Group B2, and Group B1 and Group B2(p<0.05).The mid-term follow-up X-ray showed 6 cases (30%) in Group A with osteolysis and radiolucent line around the cup, probable loosing in 4 hips and 2 positive loosing in 2 hips which received revision operations. In 4 cases in Group B1 (6%), there were osteolysis and radiolucent line around the cup, no one receiving the revision operation, and no osteolysis or radiolucent line was found in Group B2. The liner wear rate of cups in Group A, Group B, Group B1 and Group B2 were respectively 0.28±0.11mm per year, 0.18±0.10mm per year, 0.25±0.06mm per year and 0.14±0.11mm per year. According to the ten-year Kaplan-Meier survival curves with the osteolysis radiolucent line as its end point, there was statistical significance in the differences between Group A and Group B, Group A and Group B2, and Group B1 and Group B2(p<0.05). There was no statistical significance in the difference between Group A and Group B1 (p=0.11), According to the ten-year Kaplan-Meier survival curves with the revision as its end point, there was remarkable statistical significance in the difference between Group A and Group B (p<0.05).Conclusion: (1). Besides the influence of operation techniques, the curative effect of acetabular prosthesis in cementless total hip arthroplasty is also affected by the design and the liner material of the metal prosthesis. (2).The occurrence of osteolysis and the loosing of prosthesis can be effectively cut down by reducing the use of screws and using less screw holes cups, by improving the shell-liner locking mechanism, the matching of the interface of the cup and the polyethylene liner-metallic shell and the friction interface,and by using wear-resisting materials. Thus the long-term curative effect was improved. (3).Generally, the mid-term curative effect of the Reflection cup precedes that of the Harris-GalanteⅠcup.