In vivo metacarpophalanageal joint collateral ligament length changes during flexion

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Anatomy

Background:

• The metacarpophalangeal (MCP) joint is critical for hand function.
• Understanding collateral ligament behavior during flexion is essential for diagnosing and treating joint instability.

Purpose of the Study:

• To investigate the in vivo length changes of the radial and ulnar collateral ligaments of the MCP joint during flexion.
• To analyze the differential behavior of the dorsal, middle, and volar portions of these ligaments.

Main Methods:

• Computed tomography (CT) scans of the index, middle, ring, and little fingers were obtained from six healthy adult volunteers.
• Scans were performed at 0°, 30°, 60°, and 90° of MCP joint flexion.
• Radial and ulnar collateral ligaments were measured and analyzed from reconstructed 3D images.

Main Results:

• The dorsal and middle portions of both radial and ulnar collateral ligaments progressively lengthened during flexion, reaching maximum length at 90°.
• The volar portion's length increased from 0° to 30° flexion, then decreased from 30° to 60°, reaching a minimum at 90°.

Conclusions:

• The three portions of the collateral ligaments exhibit distinct in vivo length changes during MCP joint flexion.
• These variable length changes contribute to the stabilization of the MCP joint throughout its flexion arc.