Canine TightRope® Shoulder Stabilization
The Canine TightRope® Shoulder Stabilization technique is designed for the experienced veterinary shoulder arthroscopist for stabilization of the subscapularis, medial glenohumeral ligament (MGL) or both.
To prepare patient for hanging limb technique, place the patient in dorsal recumbency and clip, prep and drape widely around the shoulder joint for access to medial and lateral aspects of the shoulder. Establish a lateral scope portal just caudal to the acromion and fully access the joint documenting all pathology present. Determine if the main pathology (e.g. laxity and/or tearing) is in the subscapularis, MGL, or both. Make a ~2 cm incision on the medial aspect of the shoulder joint immediately cranial to the pectoralis muscles. Bluntly dissect under the pecs, retracting them caudally, to the level of the joint on the medial side.
Insert the first TightRope guidewire through the medial incision and into the joint from the medial aspect such that it can be visualized on the glenoid rim at the midpoint of the “Y” of origin of the MGL. Then “walk” the point of the guidewire proximally (down with limb in hanging position) off the glenoid rim 3-4 mm (the point of the guidewire may no longer be visible). When you have it set at an optimal location, have your assistant put the wire driver over the wire and with you still holding it lock the wire driver, and then drive it into the glenoid 3-4 mm.
When the glenoid wire is placed appropriately, insert the second +/- third guidewire into the joint from the medial aspect such that it can be placed on the proximal humerus. If the pathology is primarily MGL, then put the point of the wire at the insertion of the MGL. If the pathology is primarily subscapularis, then put the point of the wire at the insertion of the subscap. If the pathology involves both, you can either “split the difference” for the humeral tunnel, or place two TRs to address both problems. When this has been accomplished, “walk” the point of the guidewire distally
(up with limb in hanging position) on the proximal humerus to ensure it will not violate the articular surface. Have your assistant put the wire driver over the wire and with you still holding it, lock the wire driver and then drive it into the proximal humerus 3-4 mm.
Once desired guidewires are set (can check using fluoro if desired), remove scope and prepare drill guide. Place target hole over the glenoid pin first and seat it firmly against the medial soft tissues. (Inset) Make a 1-2 cm incision over the proposed lateral site of the glenoid tunnel, dissect or retract the suprinatus to allow access to supraspinatus fossa. Attach the arm, and set pin sleeve to drill the pin lateral to medial such that the lateral point of the guide is seated within the supraspinatus fossa just cranial to the spine of the scapula and just proximal to the neck of the glenoid. Drill the Beath Pin through the guide lateral to medial to ensure it exits at the target site.
Next, place the target hole over the humeral pin (either one if doing two) and seat it firmly against the medial soft tissues. Make a 1-2 cm incision over the proposed lateral site for the humeral tunnels all the way down to bone and dissect an area large enough for the TR button to sit fully down on bone. Attach the arm, and set the pin sleeve to drill the pin lateral to medial such that the lateral point of the guide is on the caudodistal aspect of the greater tubercle just cranial to the acromial head of the deltoid muscle. If doing two tunnels reference "Technique for Subscapularis and MGL Repair" section of this technique guide.
Remove drill guide and arm after all Beath Pins are driven through the glenoid and humerus. Drill the humeral tunnel first (either one if doing two) over the Beath Pin from medial to lateral using the 4 mm cannulated reamer. Remove Beath Pin leaving cannulated drill bit in humerus.
Insert a TightRope® leadwire into the drill bit cannulation channel. Remove drill bit and pull TightRope leadwire through humeral tunnel making sure 3.5 mm two hole button exits on medial side.
Drill the glenoid tunnel over the beath pin from lateral to medial. Remove the Beath Pin and push the tip of the TightRope® leadwire into the drill bit cannulation channel and push the TightRope leadwire through the glenoid tunnel from medial to lateral following the drill bit as it is extracted.
Pull the TR toggle through to the lateral side, flip it, and push it down to firmly seat on bone (verify that it is well seated by palpation).
Pull the FiberTape® taut on the medial side, untwist it and make sure it lays down flat against medial capsule/tendon/ligament. Then pull it taut on the lateral side and push the button down to seat firmly on humeral bone. Take the limb down from the hanging position and put the humerus at a neutral flexion-extension angle and an abduction angle of ~0-10°. Place the Arthrex® Tensioner on either FiberTape and tension over the button to 12-15 lbs. Test the shoulder for abduction, range of motion, internal rotation and medial-lateral and cranial-caudal instability. If satisfied, then tie opposite TR. If not satisfied, change your tension or if necessary place additional fixation or redo the TR. When satisfied, tie both TR's securely over the button and close all incisions routinely. Take postoperative radiographs.
Final view of canine shoulder TightRope implant placement.
If going to use two humeral tunnels make
sure the holes are 5-6 mm apart. Drill
both humeral tunnels medial to lateral
using a 4 mm cannulated drill bit. Leave
Beath Pin in one tunnel to maintain
location while drilling other tunnel.
Insert TightRope® leadwire into drill
cannulation, remove drill, and pull
implant through humeral tunnel. Insert
TightRope leadwire into drill cannulation,
remove drill, and pull implant through
glenoid tunnel. (Same Steps as 6 & 7
when utilizing one humeral tunnel).
Pull the white strands of FiberTape®
through the first humeral tunnel so
that they are free on the medial side.
Insert Nitinol Suture Passer into other
humeral tunnel with loop on the medial
side. Place free ends of the white
FiberTape into the loop and pull through
Place the white FiberTape ends back into
the four hole TR button. Return to Step 9.
• Placed in commercially-available hobbles (Doglegg’s Shoulder Stabilization System) immediately postoperatively, which are maintained for at least four weeks, and are restricted to strict rest and leash walking only until recheck.
• Patients are examined at 10-14 days for suture removal and at 4 weeks to check shoulder stability and range of motion - based on these assessments, hobbles may be discontinued or continued based on surgeon's/rehab practitioner’s discretion.
• After hobbles are discontinued, rehabilitation therapy with a certified veterinary practitioner or therapist is recommended. Based on progression, dogs are typically returned to training 12 weeks after surgery.
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