Faculty Bibliography

BACKGROUND: Techniques for reconstruction of the dislocated acromioclavicular (AC) joint abound. Most, however, do not address the injured AC ligaments and capsule. Evidence exists supporting the horizontal stabilizing effect of these ligaments on the AC joint. A novel AC and coracoclavicular (CC) reconstruction technique with an intramedullary free-tissue graft secured by suture buttons is low-profile, technically straightforward, and reproducible. HYPOTHESIS: A novel intramedullary AC reconstruction will strengthen an isolated free-tissue reconstruction of the CC ligaments. STUDY DESIGN: Controlled laboratory study. METHODS: Six cadaveric matched pair shoulders were tested with a custom testing system. Anterior-posterior and superior-inferior AC joint displacements (mm) were measured with AC joint compressions of 10 N, 20 N, and 30 N, and with translational loads of 10 N and 15 N. The same measurements were made after performing either a free-tissue tendon allograft CC reconstruction, or a free-tissue graft reconstruction of the CC and AC ligamentous complexes in the corresponding contralateral matched shoulder. The AC ligamentous complex was reconstructed with an intramedullary free-tissue graft secured by suture buttons. Load-to-failure testing was then performed on each construct. A paired t test was used for statistical analysis (P < .05). RESULTS: Mean anterior-posterior translation of the reconstruction of the CC and AC ligamentous complexes was 50% or less than that of the CC reconstruction in all loading conditions (P < .05). Mean superior-inferior translation did not differ among the groups. Overall load-to-failure testing did not differ between groups. CONCLUSION: Intramedullary AC complex reconstruction utilizing free-tissue graft for reconstruction of both the CC and AC ligaments demonstrates significantly greater initial horizontal stability than a free tissue isolated CC reconstruction and is similar to intact specimens. CLINICAL RELEVANCE: This novel intramedullary AC ligament reconstruction may be considered when seeking to improve horizontal stability in an anatomical CC ligament reconstruction.

This biomechanical study compared 2 repair techniques for high-grade, partial, articular-sided supraspinatus tendon tears of the rotator cuff: transtendon in situ repair and tear completion with repair. Standardized, 50% partial, articular-sided supraspinatus lesions were created in 10 pairs of matched fresh, frozen cadaveric shoulders: 10 underwent partial lesion repair with an in situ transtendon technique using 2 suture anchors. In the contralateral 10 shoulders, the partial lesion was converted to a full-thickness tear and repaired with a double-row technique, using 4 suture anchors. Cyclic loading to failure of the supraspinatus tendon was performed using a material testing machine. Gap formation was measured for each rotational position and each incremental load. The in situ transtendon repair had statistically significant less gapping (P = .0001) and higher mean ultimate failure strength (P = .0011) than the double-row repair. In situ transtendon repair was biomechanically superior to tear completion for partial, articular-sided supraspinatus tears.