Functional anatomy of the lateral collateral ligament complex of the elbow: morphology and strain.

The anatomy of the lateral ulnar collateral ligament (LUCL) of the elbow was investigated in 26 fresh frozen cadavers. Two types of insertion of the LUCL were originally described but we found another type which is characterized by a broad single expansion along with a thin membranous fibre. Strain on the LUCL was measured in situ during extension and flexion with the forearm in supination, pronation and neutral. Strain in the proximal fibres started to occur at around 32 degrees flexion and peaked at between 50 degrees and 60 degrees flexion. Strains measured in the distal fibres were smaller in magnitude. Forearm rotation had little effect on strain during extension to flexion. Based on these results, we conclude that the LUCL functions in unison with the annular ligament.