Minimally invasive calcaneal osteotomies: are neurovascular structures at risk? A cadaveric study

L.W. Mason, A. Durston, G. Okwerekwu, S. Kadambande, K. Hariharan

Introduction: There are concerns with the use of the Shannon burr in calcaneal osteotomies entered from the lateral side, with the medial structures possibly at risk when performing the osteotomy of the medial calcaneal wall. Our aims with this study were to investigate the neurovascular relationships with the calcaneal osteotomy performed using a Shannon burr.

Methods: This study was performed at the anatomy department, University of Sussex, Brighton. There were 13 fresh frozen below knee cadaveric specimens obtained for this study. The osteotomy was performed using a Shannon burr using a minimally invasive technique. The neurovascular structures were then dissected out to analyse their relation and any damage.

Results: Laterally, there was no evidence of damage to any neurological structure in 11 feet. In two feet, a very small lateral calcaneal branch was transected. In both cases, this was a very proximal branch from the sural nerve. There were between one and five lateral calcaneal branches of the sural nerve, and a very proximal branch present in nine feet. The minimum distance from the burr to the sural nerve was 9mm. In all cases, the entry point was within 6mm of the closest lateral calcaneal branch. Medially, there was no evidence of damage to any neurovascular structure. Quadratus plantae was present in 12 of 13 feet acting as a barrier to the neurovascular structures, and was not breached by the burr, shielding the neurovascular structures from injury. There were one or two medial calcaneal nerve branches, which all crossed the osteotomy, but were not damaged.

Conclusion: The calcaneal osteotomy performed by a Shannon burr can cause possible damage to small branches of the sural nerve, but is protected by QP form causing damage to any medial structures.