Combined extensor pollicis brevis and radial collateral ligament injury: Three case reports

Abstract

Three cases of radial collateral ligament (RCL) rupture of the thumb metacarpophalangeal (MP) joint mad avulsion of the insertion of the extensor pollicis brevis (EPB) tendon are described. Extensor pollicis brevis injury is intimately associated with tearing of the adjacent dorsoradial capsule, as demonstrated clinically and on cadaver dissection. Tears of the dorsal capsule and EPB tendon, when associated with RCL rupture, allow palmar subluxation of the MP joint and should be repaired. The recognition of this association allows the surgeon to distinguish stable RCL injuries, treatable by a cast, from unstable RCL injuries, which should be treated surgically. Case 1 A 39-year-old right-handed man presented with an injury to the MP joint 4 weeks after a basketball struck his thumb. The joint lacked full extension, had an ulnar deviation deformity of 30 ~ , and was palmarly subluxed. The RCL was unstable and could be stressed to 60 ~ compared to 15 ~ on the normal side (Fig. 1). An x-ray film showed ulnar deviation and palmar subluxation of the thumb MP joint (Fig. 2). At surgery, the RCL had ruptured from the metacarpal. The abductor pollicis brevis aponeurosis was intact. The dorsal capsule and the EPB were torn at the same level. Traction on the distal end of the