COMPLICATIONS RELATED TO MODULARITY OF TOTAL HIP COMPONENTS

We report complications from the use of modular components in 20 hip r eplacements in 18 patients. Fifteen complications (in 13 patients) wer e related to failure of a modular interface after operation. Femoral h ead detachment from its trunnion was seen in 6 hips from trauma (3), r eduction of a dislocation (2), and normal activity (1). In one case th e base of the trunnion fractured below an extra-long modular head. In seven other hips the modular polyethylene liner dislodged from its she ll, causing severe damage to the shell in four cases with extensive me tallosis. In one other hip an asymmetrical polyethylene liner rotated, resulting in impingement of the femoral component and recurrent dislo cation. Operative errors were seen in five cases: implantation of a tr ial acetabular component in one; and mismatching between the size of t he femoral head and the acetabular component in the others. Surgeons w ho use hip replacements with modular components should be aware of the potential for operative error and of the importance of early treatmen t for postoperative mechanical failure.