Objective To compare the effectiveness and linear wear rates between high cross-linked polyethylene cup liner and traditional polyethylene cup liner. Methods A retrospective analysis was made on the clinical data of 61 patients (64 hips) who underwent primary total hip arthroplasty (THA) between January 2005 and March 2007. According to the type of cup liner, 61 patients (64 hips) were divided into 2 groups: high cross-linked polyethylene cup liner was used in 30 cases (31 hips, trial group), and traditional polyethylene cup liner in 31 cases (33 hips, control group). There was no significant difference in gender, age, body weight, etiological factor, and preoperative Harris score between 2 groups (P gt; 0.05). Complication was observed after operation; Harris score was used to assess hip function; X-ray film analysis was done to observe osteolysis and prosthesis loosening, and to measure cumulative penetration of the femoral head and linear wear rate. Results All incisions healed by first intention without complication. All patients were followed up. The mean follow-up was 6.3 years (range, 5-7 years) in trial group, and was 6.5 years (range, 4-7 years) in control group. There was no significant difference in Harris score between 2 groups at the 3 months after operation and last follow-up (P gt; 0.05). Osteolysis was observed in 3 cases (3 hips) of control group, but no osteolysis in trial group. X-ray films showed no aseptic loosening in the patients of 2 groups. The mean cumulative penetration of trial group were significantly lower than those of control group at 1-7 years after operation (P lt; 0.05). Linear wear rate of trial group [(0.025 ± 0.002) mm/year] was significantly lower than that of control group [(0.086 ± 0.005 ) mm/year] (Z=6.804, P=0.000). Conclusion High cross-linked polyethylene cup liner has the similar effectiveness as traditional polyethylene cup liner, but it has lower linear wear rate than the traditional polyethylene cup liner.
ObjectiveTo investigate the effects of the femoral head size on the linear wear rate of highly crosslinked polyethylene (HXLPE) l iner in total hip arthroplasty (THA). MethodsA retrospective analysis was performed on the cl inical data of 41 patients (43 hi ps) who underwent primary THA with HXLPE liner and different sizes of femoral heads between January 2004 and December 2007 for hip diseases. There were 22 males (23 hi ps) and 19 females (20 hi ps) with a mean age of 60.2 years (range, 35-89 years), including femoral neck fracture (26 hi ps), avascular necrosis of femoral head (8 hi ps), osteoarthritis (5 hi ps), rheumatoid arthritis (2 hi ps), and congenital hip dysplasia (2 hi ps). According to the size of the femoral head, the patients were divided into 2 groups: standard head size (26 and 28 mm) was used in 25 cases (26 hi ps, group A) and big head size (32, 36, and 40 mm) in 16 cases (17 hi ps, group B). The cumulative penetration of the femoral head, linear wear rate, and effectiveness were evaluated and compared between 2 groups. ResultsAll the incisions healed by first intention, no complications of infection, deep vein thrombosis, or nerve injury occurred. The patients were followed up 5-9 years (mean, 5.7 years). No two-stage revision was needed. Harris score was significantly improved at 3 months, 6 months, and 1, 2, 3, 4, and 5 years after operation when compared with preoperative score in each group (P < 0.05), but no significant difference was found between different time points after operation in 2 groups (P > 0.05), and between 2 groups at each time point (P > 0.05). Acetabular abduction angle was (31.4±3.8)° in group A and (32.3±4.1)° in group B, showing no significant difference (t=0.482, P=0.621). At last follow-up, no radiographic or cl inical loosening was observed in each group. At 5 years after operation, X-ray results of acetabular components showed radiolucent line ( < 1 mm) in 1 case (1 hi p) and 1 case (1 hi p) of 2 groups respectively; but X-ray results of femoral components showed no radiolucent line. There was no significant difference in the cumulative penetration of the femoral head between 2 groups at 1, 2, 3, 4, and 5 years after operation (P > 0.05). The linear wear rate was (0.026±0.007) mm/year in group A and (0.025±0.007) mm/year in group B, showing no significant difference between 2 groups (t=0.708, P=0.483). ConclusionNo association is found between femoral head size and the linear wear rate of HXLPE liner. It is an ideal interface of THA because of its low linear wear rate.