Enhancing surgical safety in lateral calcaneal plating: a cadaveric study on screw placement and fluoroscopic optimisation.

BACKGROUND

Screw placement in lateral plating of calcaneal fractures presents a challenge due to the proximity of medial neurovascular structures. This study aims to identify high-risk zones, determine appropriate screw lengths, and define optimal fluoroscopic angles to enhance intraoperative visualisation and improve surgical safety.

METHODS

Thirty-three fresh-frozen cadaveric specimens were used. Following a lateral extensile approach, locking screws were inserted through an anatomical plate into seven predefined zones using sleeve-guided drilling, without plate bending or freehand angulation. For each screw, the appropriate length was initially measured, but to facilitate identification during subsequent medial dissection, longer screws were intentionally inserted. Following screw insertion, medial dissection was performed to expose neurovascular and tendinous structures. Distances from each screw were measured at two points: (1) the actual exit point on the medial cortex, and (2) the projected trajectory of the screw. Based on these measurements, risk scores were assigned using a validated scoring system. In a separate step, fluoroscopic angle measurements were conducted. K-wires were placed into the posterior facet and the sustentacular sulcus, and the required cranial and medial angulations of the C-arm relative to the plantar referenced axis were determined for the optimal visualisation of the joint and medial cortex.

RESULTS

Zone 4 (subchondral zone) demonstrated the highest risk, with medial plantar vessels, medial plantar nerve, lateral plantar vessels, and flexor hallucis longus at significant risk, particularly at the projection point. In contrast, Zone 2 inferior and Zones 3 had lower risk scores. The anticipated screw lengths ranged from 35.49 mm to 38.73 mm across different zones. Nearly all distances between screw exit points and projections showed statistically significant differences (p < 0.05), highlighting the importance of screw length. Inter- and intra-observer reliability was good to excellent across all measurements (ICC > 0.75). Fluoroscopic analysis revealed that rotating the C-arm cranially by 34.7° relative to a plantar reference axis optimised posterior facet visualisation, while a combination of 26.09° cranial and 17.79° medial angulation provided the best imaging of the medial cortex at the sustentacular sulcus.

CONCLUSIONS

This study identifies Zone 4 (subchondral zone) as the highest-risk area for neurovascular injury in lateral calcaneal plating and highlights the importance of screw length selection, particularly reconsidering screws exceeding 40 mm, and optimal fluoroscopic visualisation of medial high-risk zones. These findings are crucial for enhancing intraoperative safety in calcaneal fracture fixation.