Ex Vivo Evaluation of Arthroscopically Assisted Shoulder Stabilization using an Intra-articular Aiming Device

Introduction: Medial shoulder instability (MSI) is a common cause of forelimb lameness in the dog. Tears in the stabilizing structures lead to acute or chronic instability leading to possible luxation or subluxation, pain, lameness, inflammation and damage to the cartilage surfaces in the long-term.

Materials and Methods: The purpose of this cadaveric study is to evaluate the use of an intra-articular aiming device (IAD) to execute either a suture toggle repair or an interference screw repair. Outcome measures included ability to resolve instability induced by arthroscopic transection of the medial glenohumeral ligament based on measurement of pre-, posttransection, and postoperative abduction angles, accuracy of placement of bone tunnels based on computed topography measurements and safe application based on visual inspection of the joint surfaces for damage.

Results: The IAD could be used to produce a successful outcome by either technique however the suture toggle was superior in all respects. The authors also found the suture toggle faster and technically easier to execute. Both methods were relatively much less technically demanding than recently described techniques and could be executed very quickly.

Discussion/Conclusion: Limitations of this study include its ex vivo nature and lack of comparative mechanical properties between the two implant systems used. Further study is indicated to evaluate the mechanical properties of these repairs, as well as in vivo performance, preferably including dynamic assessment.

Acknowledgment: Implants for this study were provided by Arthrex Inc., Naples, FL. The primary author is a consultant for Arthrex Vet Systems, Naples, FL.