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

Abstract

BackgroundSeveral 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.MethodsSix 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.ResultsIntramedullary 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).ConclusionsIntramedullary 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.

Acromioclavicular reconstruction techniques after acromioclavicular joint injuries: A systematic review of biomechanical studies

“…The search strategy resulted in 413 studies. After screening and eligibility assessment, 19 biomechanical studies were included in this review (Abrams et al, 2013;Beitzel et al, 2014;Dyrna et al, 2018;Freedman et al, 2010;Garg et al, 2013;Gonzalez-Lomas et al, 2010;Grutter and Petersen, 2005a;Hislop et al, 2019;Ibrahim et al, 2020;Lädermann et al, 2013;Martetschläger et al, 2013;Morikawa et al, 2020a;Morikawa et al, 2020b;Peeters et al, 2020;Saier et al, 2015;Schär et al, 2019;Shin et al, 2014;Theopold et al, 2019;Weiser et al, 2017) (Table 2).…”

“…In 12 studies, the native AC joint was tested before the AC and CC ligaments were cut and subsequentially reconstructed (Abrams et al, 2013;Beitzel et al, 2014;Dyrna et al, 2018;Gonzalez-Lomas et al, 2010;Grutter and Petersen, 2005a;Hislop et al, 2019;Lädermann et al, 2013;Morikawa et al, 2020a;Morikawa et al, 2020b;Saier et al, 2015;Shin et al, 2014;Weiser et al, 2017). Three studies used an intact matched shoulder to compare the results with the contralateral reconstructed shoulder (Freedman et al, 2010;Garg et al, 2013;Martetschläger et al, 2013).…”

Coracoclavicular Ligament Reconstruction

“…Rieser et al 2 and Lädermann et al 25 compared TightRope (Arthrex) to various locking plates. Martetschläger et al 36 evaluated CC ligament reconstruction using CC polydioxansulfate (PDS) cerclage and Garg et al 37 evaluated free-tissue graft reconstruction of the AC joint.…”

Évaluation biomécanique d’une nouvelle technique de stabilisation acromio-claviculaire par réparation directe

“…However, there is no consensus in the definition of clinical failure. There are studies that use translational loads of only 15 N to evaluate the impact of the AC capsule and ligaments more specifically [18,19]. Although it might be theoretically sound, the results from these studies are impossible to transfer to practice because the weight of the arm already exceeds this force without any movement.…”