Anatomy of the Radial Collateral Ligament of the Index Metacarpophalangeal Joint

Abstract

To describe the origin and insertion of the radial collateral ligament (RCL) of the index metacarpophalangeal (MP) joint, relative to the MP joint line and other landmarks readily discernible intraoperatively. We dissected 17 fresh-frozen human cadaveric index fingers. We removed all overlying soft tissue from the MP joint except for the proper RCL. We dissected the RCL from its original insertion under loupe magnification while concurrently marking the ligamentous origin and insertion points. We measured distances of these points in relation to the bony landmarks (dorsal, articular, and volar surfaces) using digital photo analysis. The same observer recorded all measurements to reduce systematic error. The center of the metacarpal attachment of the RCL was located 5.4 ± 1.1 mm from the dorsal border of the metacarpal, 8.0 ± 2.2mm from the volar border of the metacarpal, and 10.3 ± 3.2mm from the articular surface of the MP joint. The total width and height of the metacarpal origin site were 5.8 ± 1.6 and 6.4 ± 1.4 mm, respectively. The center of the proximal phalanx attachment of the RCL was located 6.8 ± 1.4 mm from the dorsal border of the proximal phalanx, 5.7 ± 0.9 mm from the volar border of the proximal phalanx, and 4.4 ± 0.8mm from the articular surface of the MP joint. The total width and height of the phalangeal origin site were 5.0 ± 1.1 and 5.7 ± 0.9 mm, respectively. Our study defines the anatomic origin and insertion of the RCL of the index MP joint in relation to landmarks that are identifiable during surgery. We believe this information will be useful to surgeons when repairing or reconstructing the RCL, allowing for recreation of normal RCL anatomy.