Anatomy of the Palmar Plates: Comparative Morphology and Motion Characteristics

Abstract

The metacarpophalangeal (MCP) joints and the proximal interphalangeal (PIP) joints have different tolerances for immobilization in a flexed position. Clinically the MCP joints usually tolerate immobilization in flexion with less loss of motion than the PIP joints (with joint contracture probably related to soft tissue stiffness involving the palmar plates, collateral ligaments, and joint capsule). The palmar plates and associated check-rein ligaments have been implicated in the formation of contracture of the PIP joint.13,14 Although the anatomy of the PIP joint palmar plates has been studied,1,4,9,13 little data is available concerning the anatomy of the MCP joint palmar plates and the anatomical differences between the palmar plates of these two joints. Watson14 has hypothesized that certain differences in the anatomy and motion characteristics of the palmar plates of these joints explain their different degrees of tolerance to immobilization in flexion. The purpose of this study was to evaluate this hypothesis by examining in greater detail both anatomic differences between these palmar plates and differences in motion characteristics.