Anthropometry of the human calcaneus and orientation of the articular facet for the cuboid bone as a basis for anatomically correct positioning of osteosynthetic screws in fracture treatment.

Purpose: Fractures of the calcaneus are reported most commonly in the tarsal region. Their incidence is highest among active people in productive age. As such, optimal treatment can have vast implications for patients. The study aimed to compare calcaneal proportions of the Czech population in the last centuries to present day, for a precise choice and positioning of the osteosynthetic material, and its safe implantation in the anterior part of the calcaneus. Furthermore, we describe the frequency of the calcaneocuboid joint involvement in calcaneal fractures.

Methods: We obtained 69 macerated (dry) human calcanei from anatomical collections along with multiplanar reconstructions obtained from 43 serial CT scans from patients with injuries other than calcaneal fractures. Specimens were measured using a modified set of Bidmos et al. criteria (2006). Two groups (CT scans of macerated specimens and patients' CT scans) were statistically evaluated and compared with the help of an experienced statistician. Furthermore, scans of 80 surgically treated patients were retrospectively assessed for calcaneocuboid joint involvement.

Results: The median tilt of the calcaneocuboid joint in the transverse plane was 67° in the anatomical specimens and 72° in the multiplanar reconstructed CT scans taken from patients with intact tarsal regions. These results suggest that the length of screws should be ideally in the range between 21.3 and 25mm. In 47.3% of the patients presenting with a fractured calcaneus, the calcaneocuboid joint was involved. There was a statistically significant difference in most of the variables observed between the two groups.

Conclusion: As the calcaneocuboid joint involvement appears to be present in up to 50% of cases, adequate care should be taken. To maximize the biomechanical properties of the construct and to minimize the risks, our findings suggest the screws should be at an inner tilt of 68-74° from the lateral calcaneal wall and be of 23.5-26.2mm length. However, due to differences between the two groups and the small sample size, further investigation is needed.