Clinical characteristics and long-term mortality of occult hip fracture elderly patients

Background and objective: Occult hip fractures (OHF) occur in a minute population of patients. Diagnosis is made via magnetic resonance imaging (MRI) or alternatively via bone scan. Very little is known about the clinical characteristics of OHF patients. Our aim was to characterize the clinical and long-term survival of OHF in elderly patients and to determine if a certain subgroup of patients would benefit from an MRI investigation following normal or equivocal radiography. Methods: Twenty-nine OHF patients diagnosed by a bone scan during 1995-2004 were compared with a control group of 94 randomly chosen hip fractured patients diagnosed by plain radiography in the same hospital and during the same period. Results: Mean age, women/men ratio, place of residence, comorbidities, cognitive and functional status were similar in the OHF and control group. Twenty-two (75.9%) and 4 (13.8%) patients in the OHF group had had subcapital and intertrochanteric fractures respectively, vs. 41 (43.6%) and 47 (50%) in the control group (p = 0.003). Diagnosis delay in the OHF group was 16.8 ± 26.5 days vs. 2.5 ± 2.9 days (p < 0.001) in the control group. There were fewer operations and complications in the OHF group compared to the control group (p < 0.001 and p = 0.017, respectively). During a 13-year follow-up, no differences in survival were found between the two groups nor any differences between those operated on and those who were not. Conclusions: OHF patients have no distinctive clinical characteristics or long-term survival. The delay in diagnosing OHF is too much long and is probably related to the high prevalence of conservative treatment. MRI investigation is recommended whenever OHF are suspected and surgical treatment is considered, in order to improve diagnosis and treatment.