Unusual cup reconstruction of massive acetabulum perforation in neglected femoral neck osteoporotic fracture: A case report

INTRODUCTION: Uncemented total hip for neglected nonunion femoral neck fracture hopefully could minimize the post operative complications. Nevertheless, due to plasticity of the brittle osteoporotic bone, unexpected fracture may occur. We presented an unusual reconstruction of acetabulum which was accidently perforated during uncemented cup insertion. PRESENTATION OF CASE: A 76 years old wheelchair bound female showed a nonunion fracture of the right femoral neck due to a fall 7 years ago. She had right hip instability with 5 cm leg shortening. Uncemented total hip replacement was originally planned, however, due to unexpected perforation of the acetabulum, it was ended in total hip after creating a composite layers to fix a cemented cup. Patient was full ambulatory with walker at 4 months. Harris Hip Score at 15 months showed 71.3%, compared with 20.2% before surgery. DISCUSSION: The plasticity of the osteoporotic acetabulum floor was the reason why the uncemented cup could not be fixed, instead it caused massive perforation of the floor. The acetabulum reconstruction was done by composite layers made from remaining chondral bone shell, absorbable hemostatic gelatin sponge and cancellous bone of the femoral head, porous collagen matrix and uncemented titanium acetabulum cup fixed with two screws. CONCLUSION: In unexpected acetabulum perforation, the remaining chondral shell of femoral head together with uncemented cup as a cage support and bone cement can be used to reconstruct the acetabulum floor. More stability can be achieved using reconstruction cage with allograft and or metal augments or using a cemented total hip arthroplasty.