CT-Based Morphological Assessment of the Proximal Fibula and Its Implications for Intramedullary Nail Design

This study retrospectively collected fibular CT data for three-dimensional reconstruction to characterise proximal fibular morphology and support the design of proximal fibular intramedullary nails. Using the full fibular length as the reference, the 10%–30% segment was subdivided into 10 equally spaced cross-sections (S1–S10). Cross-sectional segmentation, anatomical landmark extraction, and measurement of the fibular head coronal angle (FHCA) were performed in 3-matic. Using exported cortical boundary and landmark coordinates, R 4.4.3 was used to calculate the maximum intramedullary diameter (MAD), minimum intramedullary diameter (MID), canal shape index (CSI), circumferential cortical thickness, and segmental minimum medullary diameter (SMMD) for each cross-section. Sixty-three fibulae from 50 adults were included. The mean FHCA was 5.28°. MAD and MID generally declined from S1 to S10, predominantly between S1 and S5, whereas CSI increased progressively. The mean SMMD was 3.18 mm in males and 2.40 mm in females. Males exhibited significantly larger MAD, MID and SMMD than females (P < 0.05). Circumferential cortical thickness was greater anteriorly and posteriorly, and smaller medially and laterally. This study offers preliminary anatomical evidence for proximal fibular intramedullary nail design. Further validation is needed to confirm the feasibility and clinical applicability of such implants.