Relationships of the sural nerve with the calcaneal tendon: an anatomical study with surgical and clinical implications

The percutaneous repair of the calcaneal tendon (CT) places the sural nerve (SN) at high risk for injury up to 60%. The aim of our study, therefore, was to explore and describe the course of SN in relation to the CT and to provide an anatomical description of the area in which the SN resides in order to assist surgeons in avoiding iatrogenic injury during surgical procedures in the leg. Forty-four lower extremities of 22 adult cadavers were dissected and the course of the sural nerve investigated. The CT was divided into ten horizontal equal fractions. The widths of CT, and horizontal distances of the SN and small saphenous vein (SSV) to a vertical line connecting the midpoints of these fractions were measured. All the measurements were obtained using a computer-assisted image analysis system. In 95.5% of the specimens the sural nerve was medial to the lateral border of the CT proximally and was intersecting with the lateral border of the CT at the 55% of the mid-tendon line. The SN divided into its terminal branches at a mean of 90% of the mid-tendon line. Based on our results, the course of the sural nerve is quite variable and seems to have the highest risk of injury at its proximal portion. The sutures placed on the CT distal to the 55% of the mid-tendon line may decrease iatrogenic nerve injury.