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[Extra-large uncemented acetabular components for hip revision].

OBJECTIVE
To investigate the early-term effectiveness of extra-large uncemented acetabular components for hip revision in the treatment of extensive acetabular bone defect.


METHODS
Between September 2008 and May 2012, 13 patients (13 hips) with extensive acetabular bone defect underwent first hip revision using extra-large uncemented acetabular components (Jumbo cup). The diameter of Jumbo cup was larger than or equal to 64 mm for male and 60 mm for female. There were 4 males and 9 females with an average age of 64.7 years (range, 58-84 years). The period from primary arthroplasty to revision was 3-16 years (mean, 9.6 years). According to Paprosky classification, acetabular bone defect was rated as stage IIA in 2 cases, as stage IIB in 5 cases, as stage IIC in 4 cases, and as stage IIIA in 2 cases. The preoperative vertical distance from the center of involved femoral head to interteardrop line was (21.2 +/- 6.1) mm longer than that of normal side. The Harris score and the rotation center of hip were evaluated preoperatively and postoperatively.


RESULTS
Healing of incision by first intention was obtained in all patients, and no complication of dislocation, infection, and injury of sciatic nerve or femoral nerve occurred. The duration of follow-up ranged from 13 to 40 months (mean, 23.5 months). Partial or complete pain relief was achieved in all patients. The other patients could walk independently and restored to their routine jobs except for 1 case of hemiplegia caused by acute cerebral infarction at 3 months after surgery. In 5 patients with bone implantation, with the prolonging follow-up, the allograft could integrate with the host bone without absorption, and the bone fusion time was 9-35 months (mean, 14.5 months). At last follow-up, the X-ray films revealed that the vertical distance from the center of involved femoral head to interteardrop line was (6.0 +/- 3.1) mm longer than that of normal side, which was significantly reduced when compared with preoperative value (t=11.13, P=0.00). No periprosthetic transparent region, prosthesis displacement, or screw breakage occurred. The Harris score was significantly increased from 30.4 +/- 8.8 preoperatively to 85.1 +/- 3.2 at last follow-up (t-22.11, P=0.00).


CONCLUSION
The application of extra-large uncemented acetabular components could be an effective technique for the reconstruction of extensive acetabular bone defect, and gain a good early-term effectiveness. The long-term survival rate of prostheses needs to be followed up.