An Anatomic Study of the Lateral Dorsal Cutaneous Nerve Using 3-Tesla MRI: A Comparison to Cadaveric Data With Surgical Applications

Abstract

Background: The lateral dorsal cutaneous nerve (LDCN) and the anastomotic branch of the sural nerve (AB) are cutaneous sensory nerves at risk of iatrogenic injury during lateral foot surgery. This study is the first to use a large cohort of high-resolution magnetic resonance images (MRIs) of the ankle to better describe the course of these nerves in vivo in order to aid surgeons intraoperatively. Our study intends to build on the “high and inside” approach to the proximal 5MT by accounting for variations in course of the LDCN and AB. Methods: One hundred twenty-five 3-tesla (T) MRI studies of the ankle were analyzed. Three reviewers measured the distance from the LDCN and AB to landmarks including the most proximal aspect of the fifth metatarsal tuberosity (5MT) and the peroneus brevis tendon (PBT). Results: Mean vertical distance from the LDCN to the 5MT was 0.8 ± 0.2 cm. Presence of an AB was visualized in 59 of 125 studies (47.2%) and was found 2.2 ± 0.5 cm dorsal to the 5MT. The AB was found to become superior to PBT at a horizontal distance 1.9 ± 0.5 cm proximal to the 5MT. The LDCN was found superior to the PBT at its insertion onto the 5MT in approximately 10% (n = 12) of our studies. During these instances, the LDCN was located an average of 0.3 cm dorsal to the PBT. Conclusion: Our proposed “safe zone” for the approach to the proximal 5MT remains superior to the LDCN and inferior to the AB and avoids crossing directly over either nerve in >95% of analyzed MRI studies. This incision begins 1.5 cm dorsal to the most proximal aspect of the 5MT and extends no more than 1 cm posteriorly. Careful dissection and identification of the LDCN and possible AB is necessary prior to further extension of incision. Level of Evidence: Level IV, case series.

Anterior Tibial Artery Danger Zone During Anterolateral Plate Fixation of the Distal Tibia: A 3D CT Angiogram Modeling Study

“…The findings help bolster the current literature by adding significant sample size, highlighting previously underappreciated anatomic variability, and further demonstrating the utility of imaging and software modalities for in vivo anatomical characterization. 17,18 In comparison with previous cadaveric studies, 3D CTA modeling avoids changes to the structure and orientation of soft tissues associated with embalming and dissection processes and, therefore, allows all soft tissue structures to remain in their native state. Further study of this 3D CTA modeling technique may help elucidate its broader application and utility in achieving safer percutaneous placement of orthopaedic implants.…”