The calcaneus as the site of manifestation for osteoporosis-associated fractures.: Age- and sex-specific changes in calcaneal morphology correlate with the incidence and severity of intra-articular calcaneal fractures

Background. While it is recognized that trauma energy at the time of injury is an important factor in the pathogenesis and severity of calcaneal fractures, the possible role of changes in calcaneal microarchitecture remains largely undefined. The purpose of this study was to determine whether the calcaneal bone structure changes with age and to address if local bone mass is of clinical relevance in respect to the occurrence and complexity of calcaneal fractures. Material and methods. The radiographic and clinical data of 182 patients with intra-articular calcaneal fractures were analyzed to provide correlative clinical evidence for a relation between local bone mass and fractures of the calcaneus. To measure bone mass, 60 calcanei were harvested from 30 age- and gender-matched patients at autopsy. Results. The average age at the time of fracture was higher in females (46.0 +/- 18.3 years) than in males (39.9 +/- 13.9 years). Furthermore, the relative frequency of fractures during aging shifted from males to females and the frequency of compound fractures was higher in females (65%) than in males (48%). The calcaneal bone mass was significantly reduced by 19% in older females (female 20-40 years: 292 mg/cm(3); female 61-80 years: 237 mg/cm(3); p < 0.05). Conclusion. The calcaneus displayed age- and gender-related changes in its microarchitecture that are known to reduce the biomechanical stability of trabecular bone. These results suggest that bone mass and structure are risk factors in respect to the occurrence and severity of calcaneal fractures.