SLR - January 2020 - Kalli E. Mortenson
Reference: Park JH, Park KR, Kim D, Kwon HW, Lee M, Choi YJ, Kim YB, Park S, Yang J, Cho J. The Incision Strategy for Minimizing Sural Nerve Injury in Medial Displacement Calcaneal Osteotomy: A Cadaveric Study. Journal of Orthopedic Surgery and Research. 2019 Nov; 14(356): 1-6.Scientific Literature Review
Reviewed By: Kalli E. Mortenson, DPM
Residency Program: Beaumont Wayne Hospital, Wayne, MI
Podiatric Relevance: The medial displacement calcaneal osteotomy (MDCO) is a well-known and frequently utilized surgical technique to correct hindfoot valgus. The procedure is routinely performed open to achieve adequate displacement of the posterior calcaneus. Common post-operative complications include wound dehiscence, infection and sural nerve injury. Previous literature has reported a 6.8 percent to 25 percent rate of sural nerve injuries following an open approach to the MDCO. The present study sought to describe the anatomic course of the sural nerve in relation to landmarks that would be easily identifiable intra-operatively, and to verify the relationship between the sural nerve to the established reference points. The authors hypothesized that an established reference area would help minimize sural nerve injury during a MDCO procedure.
Methods: Twenty formalin fixed cadaver specimens were used for the present study. The specimens were stabilized in a lateral position and four reference points, previously described by Geng et al., were identified and marked. Point A was identified as the tip of the lateral malleolus, Point B as the inferior margin of the calcaneus, Point C as the posteroinferior aspect of the calcaneus and Point D as the lateral border of the Achilles tendon. Together, these four points map out a point of interest in the shape of a square on the posterior lateral aspect of the foot and ankle. Careful dissection then took place within the reference points to identify the sural nerve. The distances from the identified sural nerve on all specimens to Point A-D were then measured using a surgical ruler.
Results: Two researchers measured the distances repeatedly on each specimen and the averages of the two were utilized as the adopted value. Results concluded that the sural nerve ran a mean of 14.45 mm inferior to the tip of the lateral malleolus and 15.65 mm posterior to the tip of the lateral malleolus. The authors concluded that ratios between the references points could establish a practical zone for surgical application. More than one half of the horizontal distance between Points A and B (ratio 0.45), more than one half of the vertical distance between Points A and D (ratio 0.50), and more than one third of the diagonal distance between Points A and C (ratio 0.33) established the practical zone for sural nerve preservation.
Conclusions: MDCO is a procedure frequently used for the treatment of adult acquired flatfoot deformity. Historically the procedure includes an oblique incision to the lateral heel, however, the sural nerve runs superficially on the lateral aspect of the heel and is vulnerable to iatrogenic injury during surgical dissection. The ratios presented in this study suggest that a skin incision more than one third of the distance from the tip of the lateral malleolus to the posteroinferior apex of the calcaneus, and more than one half the distance from the tip of the lateral malleolus to the inferior calcaneus and to the lateral border of the Achilles tendon would yield a practical reference point to reduce the incidence of iatrogenic sural nerve injury during MDCO.