Workup
Imaging Studies
Radiography of the hands should be included as part of the workup for stiff joints. Although radiography is not helpful in diagnosing intrinsic contracture, it may be useful for ruling out other diagnoses or causes of a contracture.
Shear wave elastography has been studied as a means of achieving a quantitative evaluation of the condition of the intrinsic muscles of the hand. [14]
Media Gallery
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Metacarpal head is uniquely shaped: ovoid in sagittal plane and widening from dorsal to volar dimension. Collateral ligaments are eccentrically mounted dorsal to axis of rotation of metacarpophalangeal joint. This anatomy causes variable degrees of tightness on collateral ligaments based on position of joint via camlike effect. When joint is in extension, collateral ligaments are lax; in flexion, collateral ligaments span greater distance and are tight.
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Proximal interphalangeal (PIP) joint collateral ligaments originate close to axis of rotation, providing smaller change in length with joint position and providing lateral stability. PIP joint ranges in only one plane, and its trochlear shape also adds to its lateral stability.
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Architectural differences exist between volar plates of metacarpophalangeal (MCP) and interphalangeal (IP) joints. MCP volar plate is composed of crisscrossing bands of fibers that collapse like accordion on flexion and expand with extension. IP volar plate is more rigid cartilaginous structure that does not collapse but glides with movement. It is attached to proximal phalanx only by proximal checkrein ligaments; therefore, rigid IP volar plate can slide proximally and distally with joint motion to protect joint.
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With injury, checkreins form at IP joints. Checkreins are collagenous bands connecting lateral sides of proximal volar plate to assembly lines on volar lateral surfaces of phalanx. Assembly lines are two ridges along volar lateral surfaces of phalanx to which are attached volar ligamentous structures (eg, flexor sheath, Cleland and Grayson ligaments, and oblique retinacular ligaments of Landsmeer).
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