These authors sought to determine the factors associated with achieving the minimum clinically important improvement in the Simple Shoulder Test (SST) in 42 patients (24 males/18 females) at a mean of 48 months (range, 24–132 months) after hemiarthroplasty for cuff tear arthropathy performed between 1991 and 2007.
The authors' indication for hemiarthroplasty was superior translation on plain radiographs of the humeral head with respect to the glenoid, loss of articular surface of the humeral head, bone loss of the superior glenoid, and erosion of the greater tuberosity and undersurface of the acromion. They excluded shoulders with instability of the shoulder with attempted forward elevation (anterosuperior escape), active infection, and inflammatory arthritis.
21 shoulders received a conventional humeral head replacement and 21 received a cuff tear arthropathy arthroplasty prosthesis. At surgery, soft tissue balancing
was thought to be ideal when the following criteria were achieved: (1) posterior drawer testing with 40% to 60% translation of the center of the prosthetic head relative to the center of the glenoid, (2) 60 internal rotation was present with the arm positioned in 90 abduction, (3) the hand on the involved side could be placed on the superior aspect of the contralateral shoulder without protraction of the scapula, and (4) there was 45 external rotation with the subscapularis approximated to the proximal humeral osteotomy site. Assisted motion was started immediately after surgery with progressive activities as comfort allowed.
At latest followup, 33 of 42 patients (79%) achieved a clinically important percentage of maximum possible improvement (%MPI), defined as an improvement of 30% of the total possible improvement on the 12-point SST scale. They reported no complications and no revision procedures.
Intraoperative findings of a rotator cuff tear limited to the supraspinatus and infraspinatus and limited preoperative external rotation were associated with achieving the defined minimum functional improvement (30% of MPI) on multivariate analysis. Preoperative active elevation and use of a CTA-specific implant were not significantly associated with achievement of 30% of MPI.
The results of the univariate analysis are shown here
and the results of their multivariate analysis are shown here
Comment: As appears to be the case in the practice of these authors, many of our patients with classical cuff tear arthropathy want to lead active lives. They wish to avoid a reverse total shoulder because of concerns about activity limitations, dislocation, screw breakage or humeral shaft fracture should they fall. If these individuals have active elevation > 90 degrees and have no evidence of anterior superior instability, we discuss the option of a CTA prosthesis.
Here's the example of a lady in her mid sixties with a failed cuff repair. Two years after that surgery she presented to us with a weak and painful shoulder. She was taking prednisone, methotrexate and Humira for her rheumatoid arthritis. She had active elevation to 110 and passive elevation to 160 degrees. Her x-rays at this time are shown below.
She elected a CTA arthroplasty. At surgery she had an irreparable cuff defect involving her supraspinatus and infraspinatus.
She dropped by to see us nine years after surgery. Her films at that time are shown below.
As another example we recently we saw an active physician-rancher who had had bilateral CTA prostheses performed after failed cuff repairs. Because he recognized that his ranching was demanding on his shoulders and carried the risk of falls, he preferred the CTA over the reverse total shoulder.
Before his left shoulder surgery his films were as shown below and he reported the ability to perform only 5 of the 12 Simple Shoulder Test functions. He was able to elevate his arm to over 90 degrees and had no anterosuperior instability.
At the time of surgery he had no supraspinatus, no infraspinatus and a detached subscapularis.
We were able to reattach his subscapularis.
At four years after surgery, he could perform 8 of the 12 SST functions and had the radiographs shown below. Note the impaction grafted humeral stem and the articulation of the prosthesis with the undersurface of the coracoacromial arch.
Two years ago he presented with a similar situation in his right shoulder. His SST score was 3/12. He had active elevation of 100 degrees without anterosuperior escape. His preoperative x-rays shown below.
Here's a video of his function at his last clinic visit.
Here are the x-rays and the shoulder function of a man one year out from his CTA arthroplasty
Comment: From our standpoint, the CTA arthroplasty is a most attractive option for consideration by active individuals with cuff tear arthropathy and the ability to actively elevate the arm above 90 degrees without manifesting anterosuperior instability.
It has a very low complication and revision rate, avoids issues of modular components and activity restrictions.
Inserting the prosthesis with impaction grafting makes for an easy conversion to a reverse should that be necessary, fortunately this is rarely the case. The cuff tear arthropathy prosthesis is considered for individuals with active elevation of 90 or more degrees without anterosuperior escape – especially those who desire higher levels of physical activity or those who are at increased risk of falls. It is important to realize that this prosthesis has an extended lateral joint surface for articulation with the undersurface of the coracoacromial arch, thus it is distinct from the usual hemiarthroplasty prosthesis. The implant system should allow selection of the appropriate diameter of curvature and should enable fixation by impaction grafting.
The surgical keys to a successful CTA arthroplasty are (1) optimizing stability and (2) matching the prosthetic diameter of curvature to that of the resected humeral head. The patient positioning, anesthetic, prophylactic antibiotics, skin preparation, and skin incision are identical to that for an anatomic arthroplasty.
In exposing the humeral head, we retain as much as possible of the clavipectoral fascia attached to the coracoacromial ligament (the “CA+”) as an additional barrier to anterosuperior instability.
The subscapularis is carefully incised from the lesser tuberosity taking care to keep the subjacent capsule attached to its deep side. The humerus is exposed by gentle external rotation allowing for debridement of cuff tendon remnants and osteophytes as well as sectioning of the long head tendon of the biceps if it remains intact. The humeral head height and diameter of curvature are measured, ideally before the head is resected.
The medullary canal is entered and progressively larger reamers inserted as sizers until the diaphyseal endosteal cortex is encountered at a depth corresponding to the length of the prosthetic stem (‘love at first bite’); this reamer defines the orthopaedic axis. The humeral head is resected at an angle of 45 degrees with the orthopaedic axis; the proximal humerus is prepared as for a standard humeral arthroplasty. The lateral tuberosity is resected. The humeral head diameter of curvature is chosen to match that of the resected head. Trial reduction is carried out. The height of the prosthesis is selected so that the deltoid is under mild-moderate tension when the arm is adducted. Impaction grafting is carried out using bone from the resected humeral head. If the biceps tendon is available, an in-and-out biceps tenodesis is performed. Drill holes are placed for reattachment of the subscapularis. The is prosthesis assembled and inserted and the subscapularis is securely repaired.
Additional relevant posts can be found here and here and here
We first described our approach over two decades ago in a publication, Prosthetic replacement of the shoulder for the treatment of defects in the rotator cuff and the surface of the glenohumeral joint, which reported on twenty-one shoulders in nineteen patients, fifty-four to eighty-four years old, who had disabling pain attributable to a massive tear of the rotator cuff, accompanied by loss of the surface of the glenohumeral joint. These patients were not candidates for total shoulder replacement because of the massive deficiency in the cuff and the fixed upward displacement of the humeral head. At that time reverse total shoulder was not an option. A prerequisite for hemiarthroplasty was a functionally intact coracoacromial arch to provide superior secondary stability for the prosthesis. One important aspect of the operative technique was the selection of a sufficiently small prosthesis so that excessive tightness of the posterior aspect of the capsule could be avoided. Eighteen shoulders in sixteen patients were available for follow-up, which ranged from twenty-five to 122 months. Pain decreased from marked or disabling in fourteen shoulders preoperatively to none or slight in ten and to pain only after unusual activity in four. Active forward elevation improved from an average of 66 degrees preoperatively to an average of 109 degrees postoperatively. One patient, who had had an excellent result, fell and sustained an acromial fracture, so the functional result changed to poor. Three patients had persistent, substantial pain in the shoulder that led to a revision. Neither infection nor prosthetic loosening nor instability developed in any shoulder.
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