[Effectiveness of acetabular revision using a metal reconstruction cage]

To explore the clinical outcomes of acetabular revision using a metal reconstruction cage.

Between October 2006 and October 2013, 16 patients (16 hips) underwent acetabular revision with a metal reconstruction cage. There were 4 males and 12 females, with the mean age of 62.7 years (range, 49-78 years). The time from total hip arthroplasty to revision was 3-15 years (mean, 8.2 years). The causes for revision were aseptic acetabular loosening in 15 cases, and femoral periprosthetic fracture (Vancouver type B3) in 1 case. According to the American Academy of Orthopaedic Surgeons (AAOS) classification, there were 12 cases of type III and 4 cases of type IV; according to the Paprosky classification, there were 12 cases of type IIIA and 4 cases of type IIIB. Harris score was used for hip function evaluation, and visual analogue scale (VAS) for pain in the thigh. X-ray films were taken for imaging evaluation.

Healing of incision by first intention was obtained in all patients. Deep venous thrombosis occurred in 1 patient, and was cured after anticoagulation therapy. No complications of infection, neurovascular injury, and prosthetic dislocation were found. Sixteen patients were followed up 6.8 years on average (range, 2-9 years). The Harris score was significantly increased from preoperative 42.44±4.66 to 91.88±3.28 at last follow-up ( t=-106.30, P=0.00). Two patients had mild pain in the thigh, but pain disappeared at 1 year after operation. At immediate after operation, the abduction angle was 37-54° (mean, 42.9°). The distance between acetabular rotation centre and teardrop line was (33.67±12.19) mm for preoperative value and was (20.67±9.63) mm for postoperative value, showing significant difference ( t=-9.60, P=0.00). The distance between acetabular rotation centre and lateral teardrop was (34.98±12.30) mm for preoperative value and was (40.04±6.61) mm for postoperative value, showing significant difference ( t=-3.15, P=0.00). X-ray film results showed bony fusion at the osteotomy sites at 4 to 12 months after operation. No continuous radiolucent line, prosthetic dislocation, or osteolysis was found, and bony ingrowth was observed in all patients. No patient received re-revision due to prosthetic loosening.

The metal reconstruction cage for acetabular revision can achieve good effectiveness for patients with serious bone defect.