Collagen and Vascular Changes in the Scapholunate Ligament Following Injury: An Immunohistochemical Study.

Purpose: The scapholunate ligament (SLL) is the most frequently injured wrist ligament. The aim of this study was to investigate cellular and extracellular changes within the SLL following injury.

Methods: Fifteen SLLs were harvested, ranging between 39 days to 20 years from time of injury. These specimens were subject to immunohistochemical analysis to characterize their vascular and collagen constitution.

Results: Of the 15 ligaments, 4 were harvested <3 months from injury, and 11 harvested >3 months from injury. The mean type I collagen density was 45.6% (25.2% to 55.9%) in all specimens. The mean type III collagen density was 47% (38.2% to 51.8%) of the ligament area in specimens <3 months after injury and 30.6% (13.3% to 44.1%) in those >3 months after injury. Type III collagen density was highest in the volar subunit. Type I collagen decreased only minimally in specimens taken within 2 years of injury. The increase in the type I:III collagen ratio reflected the decline in type III collagen. Blood vessels were found in 13 of 15 specimens. Mean vessel density for all specimens was 1.3% (0% to 7.1%), with the highest density of 1.8% (0% to 10%) in the volar subunit. The vessel density decreased from 2.9% (1.3% to 4.3%) to 1.6% (0% to 10%) in the volar subunit in specimens harvested >3 months after injury.

Conclusions: Mean type III collagen density decreased with time, most notably within the volar subunit. Mean type I collagen density held comparatively stable in ligaments taken within 2 years from injury. Blood vessels were detected in 87% of specimens, with the highest density in the volar subunit.

Clinical relevance: The SLL displays a collagen profile similar to other ligaments with favorable healing capacity. The volar subunit possessed a collagen ratio and vessel density that may suggest its acute repair and inclusion in reconstructive techniques has merit.