Comparative histomorphological analysis of elbow ligaments and capsule

This study aimed to compare the histomorphology of the elbow capsule and its ligaments to gain a better understanding of the clinically relevant biomechanical stabilization. Eleven human elbows were dissected including the joint capsule with its anterior (AJC) and posterior (PJC) parts, the annular ligament (AL), the radial collateral ligament (RCL) and the ulnar collateral ligament with its anterior (AUCL), posterior (PUCL) and transverse (TUCL) parts. Hematoxylin-Eosin and Elastica van Gieson as conventional histology stainings were applied to determine collagenous and elastic fiber arrangements in transmission and polarization light microscopy. The radial collateral ligament and the anterior part of the ulnar collateral ligament showed significantly more densely packed parallel fiber arrangement than the anterior joint capsule, the posterior joint capsule, and the posterior part of the ulnar collateral ligament (p < 0.02, respectively). The PUCL had significantly more mixed tight and loose parallel arrangements than the PJC, the annular ligament, the RCL, the AUCL and the transverse part of the ulnar collateral ligamentp < 0.02, respectively), while the PJC showed significantly more interlaced mixed tight and loose fiber arrangement than the AL, the RCL and the AUCL (p < 0.003, respectively). The AJC had a significantly higher amount of elastic fibers as compared to the AL, the RCL, the AUCL and the TUCL in fascicular regions (p < 0.04, respectively), while the AUCL had significantly lesser elastic fibers than the AJC and the PJC (p < 0.004, respectively). The densely packed parallel fiber arrangement and few elastic fibers of the AUCL, RCL, and AL indicate a strong biomechanically stabilizing function. The fiber arrangement of the PUCL and the TUCL with few elastic fibers support the medial elbow stabilization. Crimping and elastic fibers provide the viscoelasticity of the joint capsule.