Pilot study of the ultrasonographic examination of the intact and transected medial glenohumeral ligament in dogs

Medial glenohumeral ligament injury is commonly reported during medial shoulder joint instability in dogs. Arthroscopy is considered the gold standard procedure, but it is invasive and requires distension of the joint. Ultrasonographic examination of the medial glenohumeral ligament has been studied as a possible, less invasive alternative to arthroscopy however it has not been considered a useful method of assessment due to the interference of the probe with the pectoral muscles. The aims of this prospective analytical randomized pilot study were to develop a standardized ultrasound protocol for visualizing the canine medial glenohumeral ligament and to compare goniometry and ultrasound findings in cadaver dogs with versus without transection of the medial glenohumeral ligament. Nine adult Beagle cadavers (18 shoulders) were used. The first six shoulders were used in a preliminary study to describe an ultrasound technique to identify the medial glenohumeral ligament. Arthroscopy was performed on the remaining 12 shoulders, with six randomly selected medial glenohumeral ligaments from these shoulders, transected during the procedure. Ultrasound examination was performed after each arthroscopic procedure by an ultrasonographer blinded to the patient group. Four medial glenohumeral ligaments (67%) were correctly identified during the preliminary study. Ultrasonographic examination failed to diagnose the transection of all six medial glenohumeral ligaments in the second part of the study. No difference was observed in the ligament thickness between the dogs with and without a transected medial glenohumeral ligament. Dogs with a transected medial glenohumeral ligament had a wider articular space compared to dogs without a transected ligament (P < 0.001), and an articular space wider than 8.2 mm was discriminatory of a transected medial glenohumeral ligament in all the shoulders. In conclusion, the medial glenohumeral ligament could be identified with a medial ultrasonographic approach of the shoulder and a wider articular space can be a sign of a medial shoulder joint instability. Further studies are needed to confirm these preliminary findings in living dogs, with and without shoulder instability.

Ex vivo evaluation of arthroscopically assisted shoulder stabilization in dogs using an intra-articular aiming device

OBJECTIVE

To evaluate the use of an intra-articular aiming device (IAD) for medial shoulder stabilization with a suture-toggle repair or an interference screw repair using bone anchors in dogs.

STUDY DESIGN

Ex-vivo Study METHODS: Specimens were randomly divided into 2 groups (anchor and suture-toggle) with 10 shoulders each. Abduction angles were measured by goniometry prior to and following medial glenerohumeral ligament transection and after receiving arthroscopically assisted stabilization with either bone anchors or suture-toggle constructs. Bone stock and insertion angles were measured with computed tomography scans. All specimens were inspected by dissection.

RESULTS

Abduction angles increased post-transection in both groups, and were restored to normal in the anchor group, but 2° smaller than normal in the suture-toggle group following stabilization. Median magnitude of bone stock surrounding all tunnels ranged between 5.9 and 12.9 mm in the anchor group and 8.8 and 15.6 mm in the suture-toggle group (p = .002). Median insertion angles at the cranial glenoid, caudal glenoid, and humerus were 17.3°, 36.8 ° and 43.4° in the anchor group, respectively, and median insertion angles at the glenoid and humerus were 38.2° and 35.6° in the suture-toggle group, respectively (p = .91). Placement of anchors were not feasible in 3 specimens in the anchor group, and mild violations of the articular surfaces were detected in 3 specimens overall.

CONCLUSION

Arthroscopically assisted shoulder stabilization with an IAD was feasible in canine cadavers.

CLINICAL SIGNIFICANCE

An IAD may facilitate arthroscopic shoulder stabilization in dogs. Further studies are warranted to evaluate safety and efficacy in a clinical setting.

Treatment of Medial Shoulder Joint Instability by Stabilization with an Arthroscopically Guided Prosthetic Ligament: A Cadaveric Feasibility Study in Dogs

OBJECTIVE

 The aim of this study was to assess the feasibility and efficiency of an arthroscopically guided ligamentoplasty of the medial glenohumeral ligament to treat medial shoulder joint instability.

STUDY DESIGN

 Six Beagle cadavers were used (12 limbs). Both arms of the medial glenohumeral ligament were severed using arthroscopic guidance. Arthroscopically guided reconstruction of the ligament was performed. Threaded sutures were fixed with a bone anchor on the medial aspect of the glenoidal cavity of the scapula, passed through a humeral tunnel and finally tensioned with a suture button on lateral aspect of the humerus. Shoulder abduction angles were measured before and after the section of the medial glenohumeral ligament, and following the surgery. Two orthogonal radiographic projections and dissections were performed after each procedure to grade the placement of the implants.

RESULTS

 Surgical repairs were achieved in 10 out of 12 limbs. The abduction angles after repair with ligamentoplasty were not significantly different from the abduction angles measured before the section of the medial glenohumeral ligament.

CONCLUSION

 Arthroscopically guided ligamentoplasty with a scapular bone anchor and a humeral drilling tunnel is feasible in cadavers, and efficient to restore acutely shoulder abduction angle in a minimally invasive manner. Further clinical studies are required to assess in vivo results.

The Shoulder Joint and Common Abnormalities

The shoulder is a complex joint composed mostly of static and dynamic capsuloligamentous structures and plays an important role in forelimb lameness. Its complex anatomy and biomechanics necessitate thorough examination and diagnostic work-up for accurate diagnosis. This article provides an updated review of common canine shoulder pathologies, including osteochondrosis, bicipital and supraspinatus tendinopathies, infraspinatus contracture, medial shoulder syndrome, and luxation.

Feasibility and safety of arthroscopic medial glenohumeral ligament and subscapularis tendon repair with knotless anchors: A cadaveric study in dogs

OBJECTIVE

To test the feasibility and safety of an arthroscopic imbrication of the medial glenohumeral ligament (MGHL) and the subscapularis tendon with knotless anchors in dogs.

STUDY DESIGN

Cadaveric study.

SAMPLE POPULATION

Ten limbs.

METHODS

Cranial and caudal arms of the MGHL were imbricated with a 2.9- or a 2.4-mm knotless anchor. A horizontal mattress suture secured with a 3.5-mm knotless anchor was used to imbricate the subscapularis tendon. Computed tomography measurements included (1) the bone stock around the anchors, (2) the angle between the anchor and the joint surface (insertion angle), and (3) the angle formed by lines tangent to the cortices of the bones (safety angle). Limbs were dissected to assess the position of anchors. Safety and insertion angles and bone stock were compared among anchors with a Kruskal-Wallis test (P < .05).

RESULTS

Surgical repairs were achieved in all limbs, with only 2 of 30 anchors incorrectly placed, both in the glenoid. The safety angle of the humeral anchor (HA; median, 89°) was greater than that of the cranial glenoid anchor (CrGA; P = .0017) and the caudal glenoid anchor (CdGA; P < .001). The insertion angle of the HA (median, 68°) was also greater than that of the other anchors (P < .001 and P = .001). The insertion angle of the CrGA (median, 26°) was greater (P = .0191) than that of the CdGA (median, 7°). All anchors were inserted at the MGHL and subscapularis footprint.

CONCLUSION

Arthroscopic imbrication of MGHL and subscapularis tendon was feasible. HA were safer to place than glenoid anchors.

CLINICAL SIGNIFICANCE

The results of this feasibility study justify further evaluation of the indications and outcomes of this technique in dogs with shoulder instability.