Three-dimensional computed tomography modeling for kinematic analysis of double-strand lateral ulnar collateral ligament reconstruction

Abstract

When treating posterolateral rotatory instability, the lateral ulnar collateral ligament (LUCL) is more commonly reconstructed than the other dynamic stabilizer structures. Although numerous surgical techniques have been described for LUCL reconstruction, studies have been limited to static analyses of single-strand reconstructions. The aim of this study was to dynamically analyze the kinematics of double-strand LUCL reconstructions with 3 different configurations of graft placement: horizontal, vertical, and triangular. Five healthy elbow joints with no signs of pre-existing pathology were scanned by computed tomography, and the images were converted into 3-dimensional models. The humeral origin and ulnar insertions of the 2 ligament strands were registered in 3-matic software for the 3 graft placement configurations. A dynamic elbow joint was simulated at 1° increments throughout the motion arc. The ligament strand lengths and the difference between them were measured. The ligament lengths for each strand for the 3 graft configurations were as follows: horizontal, 31.0 ± 4.6 mm and 34.3 ± 5.0 mm; vertical, 32.5 ± 3.6 mm and 35.4 ± 4.2 mm; and triangular, 32.0 ± 4.0 mm and 33.7 ± 3.1 mm. The minimum length differences for the graft strands through the motion arc for the horizontal, vertical, and triangular graft configurations were 1.1, 0.0, and 1.0 mm, respectively. Dynamic analyses using a 3-dimensional elbow model showed that none of the configurations for double-strand LUCL reconstruction were isometric. However, the vertical double-strand configuration was nearly isometric and may therefore serve as a coequal option.