A biomechanical assessment of a novel double endobutton technique versus a coracoid cerclage sling for acromioclavicular and coracoclavicular injuries.

PURPOSE: Recently, many acromioclavicular-coracoclavicular (AC-CC) ligament reconstruction techniques address only the CC ligament. However, many of these techniques are costly, time-consuming, and require the use of allogenic grafts, making them prone to creep and failure or novel devices making them challenging for orthopaedic surgeons. The purpose of this study was to compare the biomechanical characteristics of a double endobutton technique using a standard endobutton CL with those of a coracoid cerclage sling (CS) for reconstruction of the CC ligaments.

METHODS: Anterior-posterior (AP) translation and superior-inferior (SI) translation were quantified for eight matched pairs of intact AC joints. One shoulder from each pair underwent a double endobutton repair, using an endobutton CL modified with an additional endobutton (Smith & Nephew, Memphis, Tenn) and placed through holes in the coracoid and clavicle. The contra-lateral shoulder received a coracoid sling reconstruction using an anterior tibialis tendon. Translation testing was repeated after reconstruction, followed by load-to-failure testing. Paired t tests were used for statistical analysis.

RESULTS: The CS technique demonstrated a greater SI and AP translation than the double endobutton technique (p < 0.05). Additionally, the double endobutton technique had a greater stiffness (40.2 ± 11.0 vs. 20.3 ± 6.4 N/mm, p = 0.005), yield load (168.5 ± 11.0 vs. 86.8 ± 22.9 N, p = 0.002), and ultimate load (504.4 ± 199.7 vs. 213.2 ± 103.4 N, p = 0.026) when compared to the CS technique.

CONCLUSION: The double endobutton technique yielded less translation about the AC joint and displayed stronger load-to-failure characteristics than the CS reconstruction. As such, this technique may be better suited to restore native AC-CC biomechanics, reduce post-operative pain, and prevent recurrent subluxation and dislocation than an allogenic graft construct. The double endobutton technique may be a suitable option for addressing AC-CC injuries.