Acromioclavicular joint reconstruction implants have differing ability to restore horizontal and vertical plane...

Area of Science:

• Orthopedic surgery
• Biomechanics
• Sports medicine

Background:

• Persistent acromioclavicular joint (ACJ) instability after high-grade injuries leads to significant patient symptoms.
• Restoring both horizontal and vertical plane stability is crucial for native ACJ function.
• Current implant methods' efficacy in restoring complete native ACJ stability is not well-established.

Purpose of the Study:

• To quantitatively assess the ability of three commercially available implant reconstructions to restore native ACJ stability in the vertical and horizontal planes.
• To compare the biomechanical performance of different ACJ reconstruction techniques.

Main Methods:

• Fresh-frozen shoulders were tested using a robotic system to measure native ACJ stability (anterior, posterior, superior, inferior).
• ACJ ligaments were transected, and reconstructions were performed using tape loop/screw, tape loop/button, or suture/button systems.
• Post-reconstruction stability was remeasured and compared to native ACJ stability using statistical analysis (ANOVA, t-tests with Bonferroni correction).

Main Results:

• All three tested reconstructions successfully restored anterior-posterior (A-P) stability to native levels.
• Tape-based reconstructions (loop/screw, loop/button) resulted in anterior displacement of the clavicle.
• Only the suture and button reconstruction significantly matched native ligament restraint for superior-inferior (S-I) stability.

Conclusions:

• The suture and button reconstruction, which utilizes direct tunnels through the clavicle and coracoid, effectively restored all measured stability parameters (A, P, S, I) to native values.
• Tape implant designs that wrap around the bones led to anteriorization of the clavicle, indicating differential abilities in restoring horizontal and vertical plane stability.
• These findings highlight the importance of implant design in achieving comprehensive ACJ stability restoration.