The Course of the Terminal Posterior Interosseous Nerve and Its Relationship with Wrist Arthroscopy Portals

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.

Safe zones in dorsal portals for wrist arthroscopy: a cadaveric study

The standard dorsal portals are the most commonly used in wrist arthroscopy. This cadaveric study aims to determine safe zones, by quantitatively describing the neurovascular relationships of the dorsal wrist arthroscopy portals: 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar. The neurovascular structures of twenty-one fresh frozen human cadaveric upper limbs were exposed, while the aforementioned portals were established with needles through portal sites. The minimum distance between portals and: dorsal carpal branch of radial artery, superficial branch of radial nerve, posterior interosseous nerve and dorsal branch of ulnar nerve, were measured accordingly with a digital caliper, followed by statistical analysis of the data. The median and interquartile range for each portal to structures at risk were determined and a safe zone around each portal was established. Free of any neurovascular structure safe zones surrounding 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals were found at 0.46mm, 2.33mm, 10.73mm, 11.01mm, 10.38mm, 5.95mm and 0.64mm respectively. Results of statistical analysis from comparisons between 1-2, 3-4 and midcarpal radial portals, indicated that 1-2 was the least safe. The same analysis among 3-4, midcarpal radial, midcarpal ulnar and 4-5 portals indicated that midcarpal portals were safer, while 3-4 was the least safe. Results among midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals indicated that 6-radial and specifically 6-ulnar were the least safe. This study provides a safe approach to the dorsal aspect of the wrist, enhancing established measurements and further examining safety of the posterior interosseous nerve.

The Risk of Injury in Wrist Arthroscopy Portals: A Cadaveric Study

During wrist arthroscopy, the wrist joint can be visualized from almost every perspective through a combination of standard dorsal and volar arthroscopic portals. This cadaveric study aims to compare all wrist portals described in terms of their safety in order to rank them according to the distance from the nearest structure at risk for arthroscopic wrist procedures. Twenty-nine cadaveric formalin-embellished upper limbs were examined. Needles were inserted at dorsal and volar portal sites to perform the measurements. During the subsequent dissection, distances were measured as the shortest possible distance from the nearest structure at risk for each portal. Safe zones were determined for all portals, and the safety classification of arthroscopic wrist portals was proposed, ranking them from the safest to the most perilous. Applying the proposed safety classification to arthroscopic practice, wrist arthroscopy can be performed with a lower risk of iatrogenic complications arising from the implementation of the wrist portals.