[Acetabular revision by using uncemented cup and impacted morselized allografts].

OBJECTIVE

To evaluate the medium-term results of uncemented acetabular revision with impacted deep frozen morselized allografts.

METHODS

From April 1995 to December 2001, 58 cases (62 hips) were performed acetabular revision by use of deep frozen morselized allograft firmly impacted into localized defects as well as the entire acetabular cavity, followed by insertion of a uncemented cup with supplementary screw fixation. There were 32 males (34 hips) and 26 females (28 hips), with age of (49.6 +/- 15.4) years old. Among 62 hips, 32 hips involved in left side and 30 hips involved in right side. The cause of revision was aseptic loosening of the cup in 56 hips, septic loosening of the cup in 3 hips, and polyethylene liner dislodging with severe acetabular osteolysis in 3 hips. The average interval between the primary total hip arthroplasty and the revision was (10.1 +/- 3.9) years. According to the American Academy of Orthopaedic Surgeons classification, 42 hips belonged to type II and 20 hips to type III acetabular defects. The clinical and radiographic results were analyzed postoperatively.

RESULTS

All wounds healed by first intention. No deep venous thrombosis and infection occurred postoperatively. All patients were followed up 6-13 years (average 8.1 years). The Harris score was improved from 61.1 +/- 10.2 preoperatively to 92.0 +/- 7.3 postoperatively, showing significant difference between preoperation and postoperation (P < 0.05). The results were excellent in 46 hips, good in 10 hips, fair in 4 hips, and poor in 2 hips, the excellent and good rate was 90.3%. The time for allograft incorporation was (12.5 +/- 4.4) months after operation. The annual polyethylene liner wear rate was (0.13 +/- 0.09) mm. Linear and cavitary osteolysis was observed in 2 and 12 hips, respectively. Heterotopic ossification developed in 7 hips (11.3%); 3 hips were rated as grade I, 3 as grade II, and 1 as grade III according to Brooker classification. One cup underwent revision for aseptic loosening and 2 were defined as radiographic failures. Kaplan-Meier survival rate of the cup was 94.2% +/- 3.3% at 8 years after operation.

CONCLUSION

The combination of uncemented cup component with deep frozen morselized allografts seems to be a reliable solution for restoring bone stock, relocating the hip center, and stabilizing the cup in acetabular revision, and provides favorable medium-term clinical and radiographic results.