What is the prevalence of symptomatic or asymptomatic femoral head osteonecrosis in patients previously treated with chemoradiation? A magnetic resonance study of anal cancer patients

It is generally assumed that femoral head osteonecrosis (FHO) is a serious but rare complication of pelvic radiotherapy. A review of the literature ca rried out by the authors indicates a prevalence of 4/763 (95% confidence in terval 0.1%-1.3%). A recent publication has suggested that the prevalence o f symptomatic FHO may be much greater than previously assumed as a result o f sensitization of bone to radiation by concomitant treatment with chemothe rapy. Magnetic resonance imaging (MRI) is currently the most sensitive moda lity for detecting and confirming symptomatic or asymptomatic FHO of any ae tiology. The aim of this study therefore was to assess the prevalence of sy mptomatic and asymptomatic FHO in patients previously treated for anal canc er by chemoradiation (CRT). The hips of 34 currently disease-free individua ls (11 men and 23 women, median age 67 years, range 32-86) were scanned usi ng a coronal T1-weighted sequence. The images were assessed for evidence of FHO. The median time of scanning after the end of CRT was 35 months (range 6-107). No cases (0/34) of symptomatic or asymptomatic FHO were detected i n these patients. Given the established sensitivity of MRI in the detection of FHO, it is concluded that changes indicative of osteonecrosis were unco mmon after CRT in the current cohort of patients. Recent evidence from the literature suggests, however, that elderly females are at greatest risk of developing FHO after CRT.