Radiographic changes in bone dimensions in asymptomatic cemented total hip arthroplasties. Results of nine to thirteen-year follow-up

On twenty-six cemented total hip replacements that had been followed for an average of 10.4 years (range, nine to thirteen years), a retrospective radiographic study was done to assess dimensional changes in the cross section of the bone in a group of asymptomatic patients. Cortical dimensions were measured on radiographs and were normalized using a radiographic distortion factor that was derived from the width and length of the prosthesis. The data were then analyzed using a least-squares method. Analyses were performed for the men, for the women, and for the combined group. The results for all three groups showed a significant decrease in cortical thickness as well as widening of the medullary canal, but no periosteal expansion. Clinical Relevance: Although the bone-cement interface may appear optimum at the time of operation, with time the dimensions of the bone do change and the integrity of the bone-cement interface may be disrupted. It is not known whether these changes in the dimensions of the bone are secondary to normal age-related phenomena or are due to the presence of a cemented implant, or whether this dimensional change will lead to loosening.