10 Shoulder Arthroplasty
Summary
Shoulder arthroplasty has a variety of indications, from degenerative changes of the glenohumeral joint and cuff tear arthropathy, to fracture. 1 – 37 The deltopectoral approach serves as a utilitarian approach to the shoulder, which allows for access to perform a traditional total shoulder replacement or reverse shoulder arthroplasty in the case of rotator cuff deficiency or certain fractures. 7 , 13 , 16 Preoperative planning is imperative to ensure a successful operation, taking note of inadequate bone stock and availability of implants. 7
10.1 Preop
Surgical table. Spider chair and trimano arm or beach chair with arm holder (▶Fig. 10.1)
Patient positioning. Beach chair position with hips and knees flexed 30 degrees, back elevated 45–80 degrees and more vertical for fractures
Check the abdomen to ensure no force on the knees, which can cause mesenteric syndrome.
Patient exam. Perform thorough neurovascular exam including function of axillary nerve and identify radial pulse.
Review preop CT scan and take note of glenoid deficiency or fracture pattern. 7 , 10 , 38 , 39
Nothing by mouth (NPO) at midnight the night prior; consider clear liquids until 2 hours prior to surgery and preloading with a carbohydrate-enhanced drink for early return of GI function if allowed by anesthesia. 40 – 42
Medication regimen
Tranexamic acid (TXA). weight-based versus generic dosing just prior to induction and 3 hours after initial dose to decrease blood loss.
Decadron. 10 mg dexamethasone at induction (contraindicated in diabetics and in some with stomach ulcers).
Antibiotics
Cefazolin. Weight-based
+ Methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin 1 g (infused over at least 1 hour 40 minutes to avoid red man syndrome). Decolonization in MRSA patients with 5 days of mupirocin ointment and 5 days of chlorhexidine scrub.
Penicillin allergy. Clindamycin (usually, 900 mg)
Celebrex. 400 mg preoperatively one time (contraindicated in sulfa allergies)
Zofran. 4 mg
IV Tylenol. 1 g preoperatively one time
10.2 Approach
Infiltrate the subcutaneous tissue with epinephrine for hemostasis.
Utilize the bovie for all aspects of the approach except the skin.
Deltopectoral approach is most common; cheat lateral on the incision to retract less throughout the case.
Perform entire approach from clavicle to the deltoid insertion from the start of the procedure.
Only elevate the skin on the medial side to avoid necrosis over the deltoid.
Identify and retract the cephalic vein medially to reduce edema and coagulate any venous perforators coming from the cephalic vein to the deltoid (the cephalic vein can be taken either way, but there is less chance of injury if taken medially).
Dictate integrity of cephalic vein in operative report, as it can appear as a deep venous thrombosis (DVT) on ultrasound if ligated.
Take down adhesions between the deltoid and humerus to the subacromial space; can use Surgicel (4” × 8”) under the deltoid or small lap sponge.
Perform partial release of the anterior deltoid subperiosteally using a cobb elevator if needed for deltoid retraction.
Release up to 1 cm of the upper pectoralis with a bovie (keep the biceps intact for now, which is directly below on the medial side).
Identify the conjoint ligament originating at the coracoid, release the ligament up to the coracoid directly on bone. Try to preserve the coracoacromial (CA) ligament.
Palpate the axillary nerve (which may be tight) under the coracoid and above the subscapularis and free it up with a finger under the glenoid. Avoid clamps.
Place the arm in slight internal rotation, locate the biceps and tenodese at the upper pectoralis at the level where the pectoralis was previously released. Use a #2 Maxbraid or equivalent. Use a mattress suture to avoid strangulating the tendon through soft tissue (no bone/anchors) (▶Fig. 10.2).
10.3 Arthrotomy
Use the biceps as a guide. Release the retinaculum over the biceps (prefer mayo scissors) all the way up to the glenoid and stay on the lateral aspect of the bicipital groove (saves tissue for subscapularis repair).
Detach the biceps at its origin and cut directly above the tenodesis (preserved biceps = stiffness).
Peel the subscapularis with the bovie beginning in the bicipital groove from the scapula proximally to the level of the three sister vessels distally (anterior humeral circumflex and venae comicante). Alternatively, a lesser tuberosity osteotomy could be performed from the bicipital groove. Keep this wafer of bone thin to preserve the humeral canal, which is needed to support the humeral stem. Be aware of the location of the axillary nerve in related to the osteotomy site.
10.4 Humerus Dislocation
Abduct and externally rotate the arm to dislocate and guide the deltoid over the tuberosity to preserve the deltoid and prevent tearing.
Troubleshooting if unable to dislocate.
Inspect for missed adhesions between deltoid and humerus (should be able to completely circle the head with a finger).
Check your distal deltoid release; keep the cobb elevator transverse and push distal to elevate from the bone if needed and stay subperiosteal.
Remember. Axillary nerve is 5–7 cm lateral and inferior to the acromion from posterior to anterior on the undersurface of the deltoid; it is safe to partially detach the deltoid inferior to this point, approximately 10 cm inferior to the acromion.
May have to detach 1 cm of medial deltoid origin from the clavicle in large, muscular patients to avoid tearing the deltoid; repair at the end with soft tissue periosteal sutures or drill holes in the clavicle if take more than 1 cm.
10.5 Humeral Preparation
Most systems available use an intramedullary (IM) guide to facilitate removal of the humeral head with a saw near the anatomic neck. Start at the cartilage-bare area junction at central superior head, just medial to the supraspinatus (▶Fig. 10.3).
Resect the humeral head using 20–30 degrees of retroversion, set to the correct side (double check).
Use 30 degrees unless recurrent posterior dislocations of a primary total shoulder arthroplasty (TSA).
For posterior dislocations, use less retroversion; for anterior dislocation, use 5–10 degrees more.
Check the depth of the cut with an angel wing; the cut should be just superficial to the rotator cuff insertion (supraspinatus). Usually, 3–10 mm cut; you can always cut more.
Save the humeral head for graft in case of fractured/deficient glenoid.
Wait to cut off bone spurs until implant is in place.
Ream to light chatter by hand (avoid power).
Go 4–5 mm deeper than planned implant with the IM reamer on initial passes.
Go to desired height on final reamer.
Cut the head in 30 degrees of retroversion.
Use a version bar on every broach and reference off the forearm with elbow flexed 90 degrees. Fully seat each broach before using the teeth on the broach and rasping laterally by hand.
Over-reaming predisposes to fracture of the humeral shaft.
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