Abstract
Objectives:
The Anconeus Fascia Transfer (AFT) technique for reconstruction of the lateral ulnar collateral ligament of the elbow (LUCL) has the distinct advantage of using local tissue available within the surgical exposure. By contrast, other established techniques require the harvest of autograft from a remote site (e.g., palmaris longus tendon), or the use of an allograft. However, relevant biomechanical parameters including the ideal insertional landmark, isometry of the transferred tissue, and strength of the reconstruction require assessment before further clinical adoption. We hypothesize that the ideal humeral landmark for fixation is the center of rotation (CORA) on the lateral epicondyle, that AFT reconstruction produces a graft with similar isometry to the native LUCL, and that the strength is similar in a biomechanical model of posterolateral rotatory instability (PLRI).
Methods:
Pre-hoc power analysis was used to determine the number of specimens required for each limb of the study. To determine ideal humeral insertion, seven cadaveric upper extremities were dissected and relevant anatomy was marked with wires. The central aspect of the ulnar LUCL insertion and the proximal and distal margins (A1 and A2) of the AFT insertion were measured against a series of points on the lateral humeral epicondyle. These measurements were performed in 0, 30, 60, 90, and 130 degrees of elbow flexion. The changes in length between these points (graft elongation) along the humeral motion arc were calculated, then compared amongst different point configurations. To measure biomechanical strength, nine cadaver pairs were randomly assigned to autograft palmaris longus (PL) LUCL reconstruction or AFT reconstruction. Load to failure was assessed using an established PLRI model.
Results:
Insertion at the humeral CORA provided the lowest graft elongation when compared to other humeral insertion points for both the native LUCL and the AFT. Graft elongation between the native LUCL and the AFT were not significantly different (2.67mm ± 0.82 for LUCL, 2.62 ± 1.3 for A1, 2.86 ± 0.67 for A2). When graft elongation was compared with respect to overall length, isometry at the proximal edge of the AFT is not significantly different than the LUCL, but the distal point is more isometric than the native ligament (8.75% ± 3.31% LUCL, 5.56% ± 2.63% for A1, 4.23% ± 1.25% for A2). The mean load to failure in AFT specimens was 1.45*104 ± 4.44*103 Nmm/S, as compared to 1.15*104 ± 3.71*103 Nmm/S in the PL reconstruction specimens. This difference did not reach statistical significance.
Conclusions:
The ideal humeral insertion point for the Anconeus Fascia Transfer is the humeral CORA. The AFT provides similar isometry to a graft placed along the anatomic landmarks of the native LUCL, and the distal portion of the anconeus fascia demonstrates improved isometry. The load to failure of AFT is not significantly different than PL reconstruction.