RESUMEN
OBJECTIVE: The purpose of this article is to determine how often a malignant process presents as a lucency near a hip prosthesis, and to classify the frequency and distribution of differential diagnoses of these lytic lesions, and to determine their disposition. MATERIALS AND METHODS: Hip and pelvis imaging examinations obtained from January 1998 to June 2008 were text searched (1,164,560 reports) to identify patients with hip prostheses (3508 patients); the records were then searched and individually reviewed to identify periprosthetic lucency (2036 reports; 176 patients). The most likely cause for the lucency, as determined by the interpreting radiologist, was recorded. Malignancy was confirmed in all cases. Malignancy was excluded by biopsy for some patients but by clinical follow-up or at the time of revision, if performed, for most patients. Prevalence rates and 95% CIs were calculated. RESULTS: The overall prevalence of periprosthetic lucency was 5.02%. The prospective diagnoses suggested included loosening or infection (37.5%), degenerative cysts (19.3%), metastases (23.3%), multiple myeloma (14.8%), and metastasis of previously unknown malignancy (3.4%). The prevalence of metastases or multiple myeloma near a hip prosthesis was 1.54%; however, each of these patients had a known prior diagnosis of bone metastases, multiple myeloma, or primary bone malignancy. CONCLUSION: Among the 2036 examinations with periprosthetic lucency, there were no instances of new malignancy, metastasis, or myeloma. These results suggest that it is statistically unlikely that a lucency near a hip prosthesis represents the first presentation of malignancy or metastases, regardless of how large or aggressive it may appear on imaging.