(a, b, c, d) Preoperative radiographs
The patient’s history, physical, and imaging findings are consistent with the diagnosis of cuff arthropathy with good shoulder function. Initial treatment was nonoperative including rehabilitation and NSAIDs. A subacromial injection of lidocaine and cortisone that resulted in immediate diminished pain and persisted for several weeks was helpful in ruling out other causes of shoulder pain such as cervical radiculopathy and malingering. He had full range of shoulder motion and did not want to lose internal and external rotation with the arm at the side. When there is AC joint osteoarthritis as with this patient, I have been successful using the absence of tenderness at the AC joint and the absence of pain at the AC joint with cross-body motion in leaving the AC joint alone.
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With the patient in the Fowler position (Fig. 13.2) and the arm on a Mayo Stand a deltopectoral incision is made (Fig. 13.3). The deltopectoral interval is split and the shoulder is then extended and internally rotated to expose the rotator cuff tear. A Fukuda retractor is placed into the joint. When the superior subscapularis tendon is torn as is usually the case, the shoulder is then pushed superior to expose the humeral head (Fig. 13.4). If the entire subscapularis tendon is intact it is helpful to incise the superior third of the subscapularis tendon to aid in the exposure, and when I do this, I prefer to incise the subscapularis off the lesser tuberosity with a peel-off method. The long head of the biceps tendon is almost always torn. In the rare instance when it is not, a tenodesis can be done just below the bicipital groove. I use an intramedullary guide and a proximal humeral cutting guide to aid in the humeral osteotomy. The intramedullary guide is placed into the lateral humeral head an average of 9 mm posterior to the bicipital groove. It is sometimes difficult to find the junction of the lateral humeral head and the greater tuberosity when the cuff arthropathy is chronic and proximal humerus has a “bald eagle” appearance. Then a starting point is made so that the intramedullary guide will go straight down the humeral shaft. I position the guide in 30° of retroversion and mark the front of the humerus with a line where the osteotomy will be done (Fig. 13.5). The intramedullary guide is removed. It is helpful to see the humeral head by retracting the remaining rotator cuff both anterior and posterior to aid in cutting with the proper retroversion (Fig. 13.6). The osteotomy is made from lateral to medial at a 135° angle with the shaft (Fig. 13.7). The humeral head is removed and the diameter is measured. I like to do the humeral osteotomy this way instead of anterior to posterior as I do with patients with osteoarthritis and an intact rotator cuff tear as it preserves the subscapularis tendon and allows early active range of motion. Also, it is uncommon for there to be inferior humeral head osteophytes in patients with cuff arthropathy since, when present, excision of the inferior humeral head osteophytes necessitates incision of the entire subscapularis tendon to expose the osteophytes. The osteoarthritis in patients with massive rotator cuff tears is usually different than in those with an intact rotator cuff. It usually involves the superior humeral head and the superior glenoid as a result of the superior position of the humeral head. There can also be concentric glenoid wear. Loss of glenoid bone is a concern after hemiarthroplasty and if present before surgery and is severe can be a contraindication to hemiarthroplasty. Progressively larger broaches are then placed down the humeral canal in line with the humeral shaft and I like to do this, on average with the arm in about 30° of external rotation relative to the table so that the broach can be inserted perpendicular to the table to match the humeral retroversion (Fig. 13.8). When the surgeon gets good fixation of the broach in the proximal humeral bone, the broaching can stop as good proximal cancellous humeral bone will provide good fixation and endoseal contact with the humerus is not necessary. The head component is matched to the diameter of the humeral head that was resected. The thickness of the humeral head prosthesis can be judged as being on average three-fourths of the radius. If the shoulder has good passive range of motion and the humeral head can be translated to the rim of the glenoid, the trial components can be removed and a prosthesis with a surface for bone ingrowth can be impacted in place. Morselized cancellous bone from the humeral head can be placed in the endoseal canal of the humerus before the prosthesis to aid in fixation. It is important that the greater tuberosity is a bit below the top of the humeral head to minimize impingement of the greater tuberosity on the acromion with shoulder elevation. So, a tuberoplasty is done by debriding the bone of the top of the greater tuberosity (Fig. 13.9) so that the prosthesis is about 7 mm higher than the greater tuberosity (Fig. 13.10).
The patient positioned in the semi-Fowler’s position