Biomechanical Comparison of an Intramedullary and Extramedullary Free-Tissue Graft Reconstruction of the Acromioclavicular Joint Complex

BACKGROUND: Several different surgical techniques have been described to address the coracoclavicular (CC) ligaments in acromioclavicular (AC) joint injuries. However, very few techniques focus on reconstructing the AC ligaments, despite its importance in providing stability. The purpose of our study was to compare the biomechanical properties of two free-tissue graft techniques that reconstruct both the AC and CC ligaments in cadaveric shoulders, one with an extramedullary AC reconstruction and the other with an intramedullary AC reconstruction. We hypothesized intramedullary AC reconstruction will provide greater anteroposterior translational stability and improved load to failure characteristics than an extramedullary technique. METHODS: Six matched cadaveric shoulders underwent translational testing at 10 N and 15 N in the anteroposterior and superoinferior directions, under AC joint compression loads of 10 N, 20 N, and 30 N. After the AC and CC ligaments were transected, one of the specimens was randomly assigned the intramedullary free-tissue graft reconstruction while its matched pair received the extramedullary graft reconstruction. Both reconstructed specimens then underwent repeat translational testing, followed by load to failure testing, via superior clavicle distraction, at a rate of 50 mm/min. RESULTS: Intramedullary reconstruction provided significantly greater translational stability in the anteroposterior direction than the extramedullary technique for four of six loading conditions (p < 0.05). There were no significant differences in translational stability in the superoinferior direction for any loading condition. The intramedullary reconstructed specimens demonstrated improved load to failure characteristics with the intramedullary reconstruction having a lower deformation at yield and a higher ultimate load than the extramedullary reconstruction (p < 0.05). CONCLUSIONS: Intramedullary reconstruction of the AC joint provides greater stability in the anteroposterior direction and improved load to failure characteristics than an extramedullary technique. Reconstruction of the injured AC joint with an intramedullary free tissue graft may provide greater strength and stability than other currently used techniques, allowing patients to have improved clinical outcomes.

Resección artroscópica de clavícula distal por abordaje combinado: evaluación funcional y de la técnica quirúrgica / Arthroscopic distal clavicle resection from a combine approach: functional and surgical technique evaluation

The success of the distal clavicular resection (DCR) is related with the nonarticular contact and the preservation of the stabilizers ligaments of the acromioclavicular (AC) joint. A retrospective revision of 25 patients that underwent to an arthroscopic DCR by a bursal approach associated to a posterior AC portal was done. The average age was 50 year-old. Twenty four patients presented A Costeoarthritis and one patient a microinstability. Twenty patients presented an associated pathology, and the majority of them were rotator cuff injuries. After a follow-up of 15,2 months, 92 percent of the patients presented no AC pain. The surgical technique allows the preservation of the superior and partially of the posterior AC ligament in all the cases. Two patients presented pain and one of them was reoperated. The evaluated technique show a high rate of satisfactories results an allow the preservation of the superior AC ligament.

El éxito de la resección de clavícula distal (RCD) se relaciona con la ausencia de contacto óseo y la conservación parcial de los estabilizadores de la articulación acromioclavicular (AC). Se realiza una revisión retrospectiva de 25 pacientes sometidos a una RCD artroscópica por vía bursal asociada a un portal AC posterior. La edad promedio fue 50 años. Veinticuatro pacientes presentaban artrosis AC y uno microinestabilidad de esa articulación. Veinte pacientes presentaban una patología asociada, la que en su mayoría fue del manguito rotador. Al término de un seguimiento promedio de 15,2 meses, 92 por ciento de los pacientes no presentó dolor AC. La técnica permitió la conservación del ligamento AC superior y en forma parcial del ligamento AC posterior en todos los casos. Dos pacientes persistieron con dolor y uno de éstos fue reintervenido. La técnica evaluada logra un alto porcentaje de resultados satisfactorios y permite la conservación del ligamento AC superior.