[Total hip arthroplasty with double-tapered cementless femoral stem for hip bony].

OBJECTIVE: To investigate the effectiveness of total hip arthroplasty with double-tapered cementless femoral stem for hip bony fusion by comparing with anatomical cementless femoral stem.

METHODS: A retrospective analysis was made on clinical data of 50 cases (80 hips) of hip bony fusion undergoing total hip arthroplasty between October 1999 and January 2008. The patients were divided into 2 groups: 31 cases (49 hips) using BetaCone double-tapered cementless femoral stem (trial group), and 19 cases (31 hips) using Ribbed anatomical cementless femoral stem (control group). There was no significant difference in gender, age, disease duration, preoperative Harris score, and abduction angle of the hip between 2 groups (P > 0.05). After operation, X-ray films were used to calculate the ratio of force arm of abductor (a) to the force arm of gravity (b) and analyze the stability of the prosthesis. The abduction angle of the hip and Harris score were measured during follow-up.

RESULTS: Fracture occurred during operation in 9 hips of 9 cases (5 in trial group and 4 in control group), and was cured after fixation. The mean follow-up time was 49 months (range, 12-98 months) in trial group and was 53 months (range, 6-105 months) in control group. The ratio of a/b was 0.65 +/- 0.25 in trial group and was 0.56 +/- 0.37 in control group, showing significant difference (t = 2.19, P = 0.03). The abduction angle of hip was (34.49 +/- 7.58) degrees in trial group and was (30.97 +/- 7.24) degrees in control group at 6 months after operation, which was significantly improved when compared with preoperative value in 2 groups (P < 0.05), and significant difference was found between 2 groups (t = 2.06, P = 0.04). Postoperative Harris score was significantly improved in 2 groups when compared with preoperative score (P < 0.05); trial group was better than control group in Harris score at 1 month after operation (t = 3.62, P = 0.01), but no significant difference was found between 2 groups at last follow-up (t = 1.61, P = 0.11). At last follow-up, X-ray films showed stabilized prosthesis in 2 groups. Grade I or II ectopic ossification occurred in 12 cases (14 hips) of trial group and 8 cases (9 hips) of control group at 2 years after operation.

CONCLUSION: The total hip arthroplasty with both double-tapered and anatomical cementless femoral stems for hip bony fusion can obtain satisfactory effectiveness, while the double-tapered cementless femoral stem has better abduction angle of hip.