The Medial Triquetrohamate Portal: A New Portal in Wrist Arthroscopy. Anatomical Study.

Introduction  Continuing advances in wrist arthroscopy and better understanding of carpal conditions have created the need to design new wrist access portals that facilitate the implementation of new surgical techniques. The aim of this study was to define and verify the safety of the medial triquetrohamate (MTH) portal. Description of the technique  The MTH portal is located about 5-10 mm ulnar and 2-3 mm distal to the midcarpal ulnar portal, ulnar to the extensor digitorum communis (EDC) tendon of the fourth and fifth fingers, and radial to the extensor digiti quinti (minimi) (EDQ) tendon. Methods  An anatomical study was performed on 15 upper limb specimens from 15 human cadavers. Iatrogenic injuries to potentially at-risk neurovascular and tendinous structures were assessed, and the distance from the portal to these structures was measured. Results  There were no iatrogenic injuries to the structures at risk. Mean distances from the MTH portal to the EDC tendon of the fourth and fifth fingers and to the EDQ tendon were 4.67 ± 0.35 mm and 7.27 ± 0.18 mm, respectively. No differences were observed between the left and right wrists. The distance from the MTH portal to the dorsal sensory branch of the ulnar nerve was 15.07 ± 0.44 mm. The structure with the highest risk of injury was the EDC tendon of the fourth and fifth fingers, with a distance of less than 5 mm. Conclusions  The MTH portal is safe, reproducible and facilitates the implementation of various techniques related to midcarpal pathology.