Abstract
Purpose We propose to identify and correlate arthroscopic internal ligaments with external
ligaments, providing an accurate roadmap for arthroscopic ligament and joint anatomy.
Ligamentous laxity is considered an important risk factor in developing the common
basilar arthritis of the thumb. Controversy exists as to the precise ligamentous anatomy
of the thumb carpometacarpal (CMC) joint (CMC-I); description of the internal arthroscopic
anatomy is limited.
Methods We performed CMC-I joint arthroscopy using the 1-Ulnar (1U) and thenar portals in
five cadavers, seeking to identify the following seven ligaments arthroscopically:
the superficial anterior oblique ligament (sAOL), deep anterior oblique ligament (dAOL),
ulnar collateral ligament (UCL), dorsal trapeziometacarpal ligament (DTM-1), posterior
oblique ligament (POL), dorsal central ligament (DCL), and dorsal radial ligament
(DRL). After grading articular changes of the trapezium, we passed Kirschner wires
(K-wires) (0.028) outside-in to mark the arthroscopic insertion of each ligament on
the trapezium. Gross dissection was performed to confirm the wire placement; the anatomic
identity and position of joint stabilizing ligaments, and the location of frequently
used portals.
Results The volar ligaments—the sAOL, dAOL, and UCL—were highly variable in their arthroscopic
appearance and precise location. The sAOL is a thin veil of membranous tissue that
variably drapes across the anterior joint capsule. The reported dAOL and UCL, in our
study, correlated to a thickened portion of this veil around the volar beak and was
not consistently identified with gross dissection. In contrast, the arthroscopic appearance
and location of the dorsal ligaments—DTM-I, POL, DCL, and DRL—were consistent in all
specimens.
Conclusion Our study further defines and correlates the arthroscopic and external ligamentous
anatomy of the CMC-I joint.
Keywords arthroscopy - gross anatomy - ligament anatomy - thumb CMC - arthroscopy - thumb CMC
arthritis
