Abstract
Background Midcarpal instability is an uncommon entity characterized by pain and clunking as
the wrist moves from radial deviation to ulnar deviation. Management is primarily
nonoperative. In patients with persistent symptoms, operative treatments are divided
into soft tissue reconstruction and limited midcarpal arthrodesis.
Case Description We present a rare case of radial midcarpal instability associated with radioscaphocapitate
(RSC) ligament injury. A 20-year-old man presented with radial-sided wrist pain and
clunking with radial deviation after a fall. Wrist arthroscopy confirmed the pathology
of an RSC ligament injury resulting in an extended posture of the scaphoid and a catch-up
clunk from sudden flexion of the scaphoid in radial deviation. His RSC ligament was
recessed and he had excellent outcome at 1 year follow-up.
Literature Review Midcarpal instability was reported by Lichtman et al as a painful wrist click in
ulnar deviation and classified according to the direction of the subluxation. Radial
midcarpal instability was later described by Caputo et al in patients with rotatory
subluxation of the scaphoid. We present a previously unreported form of radial midcarpal
instability as it does not quite fit into the type III midcarpal instability with
ligament laxity of the scaphotrapeziotrapezoid joint and type IV with scapholunate
ligament disruption. The painful wrist click occurs in radial deviation as the result
of an RSC ligament injury.
Clinical Relevance We performed arthroscopic thermal capsulorrhaphy of the ulnar arcuate ligaments and
dorsal capsule and an open proximal recession of the RSC ligament. The elimination
of pain and clunking accompanied by the restoration of scaphoid flexion and return
to load-bearing activities validates the pathology and suggests the potential of this
soft tissue procedure in the treatment of radial midcarpal instability.
Keywords
arthroscopic thermal capsulorrhaphy - radial midcarpal instability - ligament recession
- midcarpal instability - radioscaphocapitate ligament
