Total Shoulder Arthroplasty – Dr. Hawkins
Positioning: Supine, 45o beach chair with head in Mayo headrest. Tip the legs up 20o, then tip the back up 25o to get 45o. The arm should be resting on the armrest. Head in the middle.
Prepping and Draping:
Shave the area. 10×10 steri-drape across the neck. Mark off the acromion. The incision is more medial than that for a Bankart repair and goes more down the arm – unlike the Bankart repair, the exposure should be extensile. It goes from just above and lateral to the coracoid, down about 15 cm. The superficial skin is incised and cautery is used to get down through the dermis. Mets for the subcutaneous tissue, and find the cephalic vein. Mobilize the vein laterally and use fingers to get down to the clavipectoral fascia overlying the conjoint tendon. Use fingers to get above the coracoid and insert the coracoid retractor.
Get through the fascia lateral to the lateral edge of the short head of biceps. This plane can be extended superiorly to the coraco-acromial ligament, which part of is incised. When doing the dissection upwards, you will run across the deltoid branch of the thoracoacromial artery – try to find it and control it before it bleeds away on you. Distally, the pec major insertion is encountered, and the top 1 cm is incised.
Now, to get access to subscap, bring in the Mayo stand and put the arm down onto it in external rotation. Identify the subscap tendon. The incision in subscap is fairly far lateral, leaving a rim and staying just medial to the long head of biceps tendon. Go through both subscap and capsule with the cautery, making a vertical incision from the rotator interval to the anterior circumflex vessels below. Tag the subscap tendon superiorly. Using the mets try to then find the plane between the subscap and capsule, and develop it with a cobb.
Next, dislocate the shoulder using a combined motion with a cobb inside the joint, and an external rotation of the shoulder. Insert an antler retractor to retract the humeral head away from the glenoid, and a Crego retractor to retract away the rotator cuff. Prepare the proximal humerus.
Start with a rongeur, and rongeur away the top part of the humeral head where the rod will go down. Then insert a currette, followed by the 6mm T-handle reamer. Go up in 2 mm increments until you get some press-fit. Then remove the T handle and prepare to osteotomize the humeral head with the 30o guide. The guide slips over the reamer and is secured, and the guide is either tapped into place with pins or just left on the reamer. Osteotomize the humeral head, and take out the reamer and guide. This cut decides the anteversion/retroversion, so make it carefully! Then you need to decide about the metaphyseal size. The stem size will be that of the reamer. Decide the metaphysis size and insert the tamp with the correct stem and metaphysis cutter. Tap this down the canal. This commits you to a body and stem size. Insert the trial, and use a rongeur to take off osteophytes that overhang.
Finally, develop the plane between subscap and the capsule. Then look inside the joint and release the labrum/capsule off the anterior half of the glenoid (may also do the posterior half.)
Now, prepare the glenoid. Insert the Fukuda retractor to retract away the humeral head. Then try to size up the glenoid. Using the drill guide, drill the center pin. Then ream to abrade the surface to a smooth surface with a single radius. Insert the guide and drill the superior and three inferior holes. Trial a component. Then soak the holes with surgicell/thrombin. Pack in the cement and cement in the glenoid component.
Impact in the humeral component after trialing the heads.