Management of Thumb Metacarpophalangeal Hyperextension in the Setting of Thumb Basal Joint Arthritis

Abstract

Thumb metacarpophalangeal (MCP) joint hyperextension is a wellestablished sequela of advanced carpometacarpal (CMC) joint arthritis. This deformity results in poor patient function because the ability to perform key pinch is negatively affected. For this reason, surgeons must consider the presence of an MCP deformity when addressing CMC arthritis. A variety of nonsurgical and surgical interventions have emerged. Surgical treatments can be grouped into four main categories: (1) volar plate advancement/capsulodesis, (2) tendon transfer and tenodesis, (3) sesamoidesis, and (4) arthrodesis. Surgical intervention is based on both the degree of deformity present and the surgeon preference. This review aims to clarify indications for various treatments of MCP joint hyperextension, outline commonly performed procedures, and report the published outcomes and potential complications of these interventions.T humb carpometacarpal (CMC) joint, or basal joint, arthritis is a common cause of hand pain in the adult population. Unaddressed arthritis may lead to a hyperextension deformity of the metacarpophalangeal (MCP) joint and adduction of the first webspace. [1][2][3][4] This results in a reduction in key pinch strength, which diminishes hand function. There are multiple treatments that exist to address MCP hyperextension in the setting of basal joint arthritis. Surgical interventions include both softtissue and bony procedures. This article focuses on understanding the etiology, progression, and effect MCP hyperextension has on hand function and reviews the various treatments that address it. Carpometacarpal and Metacarpophalangeal Joint AnatomyTreating the MCP hyperextension deformity requires an understanding of the anatomy of both the CMC and MCP joints. The thumb CMC joint is an articulation between the first metacarpal base and the trapezium. The trapezium is an eccentric saddle with concavity in the radioulnar axis and convexity