Biomechanical Comparison of Anatomic Restoration of the Ulnar Footprint vs Traditional Ulnar Tunnels in Ulnar Collateral Ligament Reconstruction

Background: Current techniques for ulnar collateral ligament (UCL) reconstruction do not reproduce the anatomic ulnar footprint of the UCL. The purpose of this study was to describe a novel UCL reconstruction technique that utilizes proximal-to-distal ulnar bone tunnels to better re-create the anatomy of the UCL and to compare the biomechanical profile at time zero among this technique, the native UCL, and the traditional docking technique. Hypothesis: The biomechanical profile of the anatomic technique is similar to the native UCL and traditional docking technique. Study Design: Controlled laboratory study. Methods: Ten matched cadaveric elbows were potted with the forearm in neutral rotation. The palmaris longus tendon graft was harvested, and bones were sectioned 14 cm proximal and distal to the elbow joint. Specimen testing included (1) native UCL testing performed at 90 degrees of flexion with 0.5 N center dot m of valgus moment preload, (2) cyclic loading from 0.5 to 5 N center dot m of valgus moment for 1000 cycles at 1 Hz, and (3) load to failure at 0.2 mm/s. Elbows then underwent UCL reconstruction with 1 elbow of each pair receiving the classic docking technique using either anatomic (proximal to distal) or traditional (anterior to posterior) tunnel locations. Specimen testing was then repeated as described. Results: There were no differences in maximum load at failure between the anatomic and traditional tunnel location techniques (mean +/- SD, 34.90 +/- 10.65 vs 37.28 +/- 14.26 N center dot m; P = .644) or when including the native UCL (45.83 +/- 17.03 N center dot m; P = .099). Additionally, there were no differences in valgus angle after 1000 cycles across the anatomic technique (4.58 degrees +/- 1.47 degrees), traditional technique (4.08 degrees +/- 1.28 degrees), and native UCL (4.07 degrees +/- 1.99 degrees). The anatomic group and the native UCL had similar valgus angles at failure (24.13 degrees +/- 5.86 degrees vs 20.13 degrees +/- 5.70 degrees; P = .083), while the traditional group had a higher valgus angle at failure when compared with the native UCL (24.88 degrees +/- 6.18 degrees vs 19.44 degrees +/- 5.86 degrees; P = .015). Conclusion: In this cadaveric model, UCL reconstruction with the docking technique utilizing proximal-to-distal ulnar tunnels better restored the ulnar footprint while providing valgus stability comparable with reconstruction with the docking technique using traditional anterior-to-posterior ulnar tunnel locations. These results suggest that utilization of the anatomic tunnel location in UCL reconstruction has similar biomechanical properties to the traditional method at the time of initial fixation (ie, not accounting for healing after reconstruction in vivo) while keeping the ulnar tunnels farther from the ulnar nerve. Further studies are warranted to determine if an anatomically based UCL reconstruction results in differing outcomes than traditional reconstruction techniques.

Automated summary

The study aimed to describe a novel UCL reconstruction technique using proximal-to-distal ulnar bone tunnels to better re-create the UCL anatomy. Biomechanical testing showed that this anatomic technique had similar stability to the native UCL and traditional docking technique, with the advantage of keeping ulnar tunnels farther from the ulnar nerve.