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.
Objective To investigate the effectiveness of acetabular revision using jumbo cementless cups. Methods Between May 1996 and May 2011, 35 patients (35 hips) underwent an acetabular revision with jumbo cementless cups, and the clinical data were retrospectively analyzed. There were 12 males and 23 females, with an average age of 64.8 years (range, 47-79 years). The time from hip arthroplaty to revision was 1-15 years (mean, 9.7 years). The causes for revision were aseptic loosening in 32 cases, femoral periprosthetic fracture (Vancouver type B3) in 2 cases, and low toxicity infection in 1 case. According to the classification of acetabular bony deficiencies of the American Association of Orthopedic Surgeon (AAOS), 6 cases were classified as type I, 9 cases as type II, and 20 cases as type III; according to the classification proposed by Paprosky, 5 cases were rated as type II A, 9 cases as type II B, 13 cases as type II C, and 8 cases as type III A. The primary hip arthroplasty cups had an outside diameter of 46-52 mm (mean, 49.6 mm), and the revision cups had an outside diameter of 56-68 mm (mean, 60.4 mm). Harris score was used for hip function evaluation, and X-ray films were taken for imaging evaluation. Results Healing of incision by first intention was obtained in all patients; without infection or neurovascular injury. Prosthetic dislocation was observed in 1 case at 20 days after operation, and was cured after expectant treatment. One patient died at 6 years after operation, and the other 34 patients were followed up 2-14 years (mean, 8.4 years). The Harris score was significantly increased from 46.4 ± 13.4 at preoperation to 90.4 ± 3.6 at last follow-up (t=18.76, P=0.00). The distance between acetabular rotation centre and teardrop line was significantly decreased, and the distance between acetabular rotation centre and lateral teardrop was significantly increased when compared with preoperative ones (P lt; 0.05). Only 1 patient received second revision for aseptic loosening after 10 years; no continuous radiolucent line, prosthetic dislocation, and osteolysis was found, and bony ingrowth was shown in the other patients. Conclusion Jumbo cementless cup for acetabular revision can achieve good effectiveness for having the advantages of simple operation, less bone grafts, and good recovery of the acetabular rotation centre.