Characterization of the Supinator Tubercle for Lateral Ulnar Collateral Ligament Reconstruction

BACKGROUND Lateral ulnar collateral ligament (LUCL) reconstruction requires proper understanding and identification of anatomic structures about the lateral elbow. The insertion site of the LUCL is based on the supinator tubercle. PURPOSE To characterize the supinator tubercle relative to other surrounding anatomic landmarks. STUDY DESIGN Descriptive laboratory study. METHODS Computed tomography (CT) scans of 10 adult elbows were retrospectively reviewed. These CT scans were converted into patient-specific 3-dimensional computer models. Using a user-defined coordinate system, an ulnar Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model. The length of the supinator crest was measured. Following this, the crest was examined for a distinct raised bony tuberosity that would be consistent with the supinator tubercle. If no distinctly raised tubercle was noted, the most prominent appearing location of the crest distal to the radial notch was considered the tubercle. The distance from the proximal radial head junction to the supinator tubercle was recorded. Finally, the distance from the supinator crest at the radial head junction to the posterior cortex in the sagittal plane was measured. RESULTS The supinator tubercle was found to be prominent in 5 of 10 ulnar models. The supinator crest was 43.59 ± 13.28 mm long, and the supinator tubercle lateral extrusion was 5.60 ± 0.90 mm. The distance between the radial head junction and the supinator tubercle was found to be 15 ± 2.37 mm, and the distance from the supinator crest at the radial head junction to the posterior cortex was 10.25 ± 2.07 mm. CONCLUSION The supinator tubercle is frequently not prominent or easily recognizable. Its relationship to other structures is of value. The proximal border of the radial head, residing 15 mm proximal to the most predictable location of the supinator tubercle, is a useful landmark when drilling tunnels during LUCL reconstructions. CLINICAL RELEVANCE Results of this study may aid proper anatomic LUCL reconstruction.