Multidetector-CT Evaluation of Bone Substitutes Remodeling after Revision Hip Surgery

Abstract

We evaluated remodeling of grafted bone substitutes after revision hip arthroplasty using serial examinations of multidetector-row computed tomography imaging. Ten patients (12 hips) had cementless revision surgery with grafting of beta-tricalcium phosphate granules and pastelike calcium phosphate cement in bone defects around the femoral component. At 3 weeks and 1 year postoperatively, the patients were evaluated using multidetector-row computed tomography imaging with a metal artifact minimizing protocol. New bone formation and changes in volume of beta-tricalcium phosphate and calcium phosphate cement were measured. At 1 year postoperatively, beta-tricalcium phosphate had decreased more than calcium phosphate cement. The residual volumes of calcium phosphate cement and beta-tricalcium phosphate were 78% (range, 37%-96%) and 30% (range, 10%-62%) of the initial grafted volume, respectively. The volume of the new bone that formed after absorption of beta- tricalcium phosphate was 34% (range, 11%-76%) of the initial beta-tricalcium phosphate volume. Use of cement in prior operations was an unfavorable factor in graft remodeling after revision surgery. Multidetector-row computed tomography is a promising tool for evaluating bone stock restoration of patients and influential factors of bone remodeling, and for clarifying remodeling patterns of various bone substitutes. Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.