SHOULDER
To understand what a Superior Capsular Reconstruction (SCR) is and why it is performed, it is essential to understand the function of a rotator cuff tear is and why the cuff may be irreparable.
The ball (humeral head), usually fits concentrically within the socket (glenoid). Biomechanically, the movement of the shoulder is controlled mainly by four tendons which wrap around the humeral head called the rotator cuff. From front (anterior) to back (posterior), these are the: Subscapularis, Supraspinatus, Infraspinatus and Teres minor. The Supraspinatus is one of the largest of the four tendons and the one most often injured. Besides motion, the rotator cuff serves a very important function: keeping the humeral head depressed so it stays concentric within the glenoid. I tell my patients that injuries to these tendons usually fall into 3 main groups. First, is an inflammatory process in which the tendons become inflamed (tendonitis), or the small fluid filled sack above the tendons known as the subacromial bursa becomes inflamed (bursitis). Second, would be a partial tear in which the side of the tendon facing the humeral head (articular side), peels back from its insertion on the humerus, but still remains attached. Similarly, the opposite side of the tendon (bursal side) which faces the bone above the rotator cuff (acromion), can rub or impinge on the undersurface of the acromion causing a partial tear. Third, the tendon(s) can develop a full thickness tear which means a portion of, or the whole tendon(s), detach from the humerus.
The first two conditions (tenonditis or partial tears) can usually be treated conservatively with anti-inflammatories, physical therapy, activity modification and corticosteroid injections. Occasionally, surgery is required to decompress the subacromial space to allow the rotator cuff to pass under the acromion more freely, or to repair a partial tear.
Full thickness tears usually do not re-attach on their own to the humeral head and will require surgery (rotator cuff repair) to fix when symptomatic. Full thickness rotator cuff tears present in various ways, but mainly fall into two categories: pain or dysfunction. The larger the tear, the more “uncovered” the humeral head becomes, leading to a superior (upwards) migration of the humerus within the glenoid. Thus, the shoulder joint becomes ECCENTRIC rather than concentric. Like any joint, this will then begin to wear out the cartilage in that joint leading to an arthritic shoulder (a condition we call rotator cuff arthropathy). The longer a rotator cuff goes without being repaired, the harder it becomes to repair. This is because over time, the rotator cuff begins to retract back away from its insertion on the humerus and the muscle attached to that tendon starts to turn into fat (atrophy) because it is not working. When we, as surgeons, can’t pull the rotator cuff back to its insertion, or the muscle attached to the tendon/s become mostly fatty, we classify that as an IRREPARABLE rotator cuff tear. The quality of that tissue is usually terrible (think of sewing wet toilet paper), and even if reattached, that tissue may quickly pull through the sutures we use to tie the cuff down.
So, what now? If we can’t repair a rotator cuff tear, what are the options for the pain and dysunction that patients experience? Of course, you could treat this conservatively for as long as you can tolerate. However, there is a limit to the number of steroid injections you can have every year. Also, steroids do well for pain, but they do not significantly improve function (in other words, you are not healing anything with them). Additionally, the longer the joint remains non-concentric and the humeral head is allowed to “ride upwards”, the more it begins to wear down. One option for older patient (around age 70), would be a reverse total shoulder replacement.
This procedure kills two birds with one stone. It replaces the worn out arthritic joint with a prosthetic replacement. It also has the biomechanical advantage of using your deltoid muscle to compensate for the loss of a rotator cuff. It is specifically designed for patients with irreparable rotator cuffs and osteoarthritis of the glenohumeral joint. The problem is the longevity of the implant and loss of bone stock on the glenoid side associated with putting in the implant. There are not many options for a failed procedure and revision surgery for failed reverse total shoulders is complicated. For these reasons, we typically do not perform this surgery in younger patients.
For younger patients with irreparable rotator cuff tears, there are not many options. One option is a latissimus dorsi transfer where one or two non-rotator cuff tendons are transferred to the humerus to substitute for the deficient or irreparable rotator cuff. This surgery is most effective for massive tears of the back (posterior) of the rotator cuff tendons. Not everyone is a candidate for this surgery. It is essential that the patient have a functions subscapularis tendon. An intact teres minor (the most posterior tendon of the rotator cuff) leads to better function. This is a large procedure and usually involves an incision rather than being done arthroscopically (through a camera). Once again, not everyone is a candidate for this procedure and the rehabilitation is significant.
The last option (and the reason for this blog) is a newer procedure called a SUPERIOR CAPSULAR RECONSTRUCTION (SCR). This is a procedure designed for patients who are younger, or older patients in which shoulder arthritis has not set in who suffer from massive, irreparable rotator cuff tears. This procedure was pioneered by Dr. Teruhisa Mihata from Japan in 2007. The premise behind the surgery is to prevent the upward (superior) migration of the humeral head after the loss of the rotator cuff. You will recall from earlier in the blog, a major function of an intact rotator cuff is to depress the humeral head so that it remains concentric in the glenoid. In the absence of a repairable rotator cuff, the SCR uses a dermal patch (Arthroflex Patch, Arthrex Inc.) to substitute for an intact rotator cuff. The procedure is done all arthroscopically. One end of the patch is fixed to the superior portion of the glenoid and the other to where the rotator cuff would normally insert on the humeral head. These are fixed into the bone with bioabsorbable suture anchors similar to what we use in routine rotator cuff surgeries.
Historically, these types of grafts have been used to augment traditional rotator cuff repairs in very thin or poor quality tissue. This procedure uses a graft which is very robust (3.5 mm thick) to prevent superior migration to keep the glenohumeral joint concentric. I believe that it is this restoration of concentricity that has led patients to a decrease in pain and improvement in function. Let’s be clear, this is not a true substitute for a rotator cuff. The rotator cuff is not normally anchored to the top of the glenoid. Its muscle belly and tendon usually pass freely over the top of the glenoid. However, I believe this is the best substitute we currently have for keeping the joint concentric, and early data seems to be promising. Mihata and his group examined 22 consecutive patients with irreparable supraspinatus and infraspinatus tears from 2007 to 2009, and prospectively enrolled them in a study. Patients experienced a 20-month duration of symptoms prior to surgery and had an average follow-up of 33 months. In general, shoulder motion increased, functional and pain scores improved, their was no significant advancement of arthritis on imaging studies and 80% of patients experienced no graft tears. Rehabilitation after SCR follows a protocol similar to rotator cuff repairs and lasts approximately 3-6 months. Dr. Mihata has subsequently expanded his study to over 70 patients and the results have remained promising. One significant benefit of this procedure is not “burning any bridges”. Meaning, if a patient fails a SCR, they can still have a reverse total shoulder at a later date.
I believe that we, at Foundry Orthopedics and Sports Medicine, have done the largest number of arthroscopic Superior Capsular Reconstructions using this patch/technique in New England. While early, we are hoping for similar results to the Japanese study. In summary, SCR may provide many patients who have been previously told that they have an irreparable rotator cuff tear with a legitimate treatment option in alleviating their pain and dysfunction. Very exciting!
