[Comparative study on high cross-linked and traditional polyethylene cup liners in total hip arthroplasty].

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 > 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 > 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 < 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.