Forearm interosseous ligament isometry

Biomechanical testing was performed to determine isometric interosseous ligament graft placement as a preliminary step for reconstruction after an axial forearm disruption. Twenty-five combinations of potential ligament graft placement were studied on 7 fresh-frozen cadavers. Suture was used to simulate these potential ligament reconstructions, and suture excursion was used as an index of isometry. Ligament orientation was defined by the angle formed between the ulna and the suture (surrogate graft). Ligament position was defined by its insertion on the ulna as a percentage of ulna length. Suture-ulna angles from 9°to 38°produced significantly less suture excursion than angles of ≥39°. Minimal suture excursion was noted at angles of ≤20°, which we feel represents the optimal range for reconstruction. The optimal location on the ulna for isometric interosseous ligament reconstruction was at 25% to 30% of total ulna length, as measured proximally from the distal ulna articular surface. The radius isometric location is optimally located by a vector starting from the ulna isometric point and directed toward the proximal radius at an angle of ≤20°relative to the long axis of the ulna. Interosseous ligament reconstruction may prove beneficial in the long-term outcome of reconstruction after axial forearm disruption.