ACETABULAR DEFECT CLASSIFICATION AND SURGICAL RECONSTRUCTION IN REVISION ARTHROPLASTY - A 6-YEAR FOLLOW-UP EVALUATION

From 1982 to 1988, 147 cemented acetabular components were revised wit h cementless hemispherical press-fit components, with an average follo w-up period of 5.7 years (range, 3-9 years). Acetabular defects were t yped from 1 to 3 and reconstructed with a bulk or support allograft. T ype 1 defects had bone lysis around cement anchor sites and required p articulate graft. Type 2A and B defects displayed progressive bone los s superiorly and required particulate graft, femoral head hulk graft, or cup superiorization. Type 2C defects required medial wall repair wi th wafer femoral head graft. Type 3A and B defects demonstrated progre ssive amounts of superior rim deficiencies and were treated with struc tural distal femur or proximal tibia allograft. Six of the 147 compone nts (4.0%), all type 3B, were considered radiographically and clinical ly unstable, warranting revision. Three of the six were revised. Moder ate lateral allograft resorption was noted on radiographs, but host-gr aft union was confirmed at rerevision. Size, orientation, and method o f fixation of the allografts play an important role in the integrity o f structural allografts, while adequate remaining host-bone must be pr esent to ensure bone ingrowth.