Arthroscopic repair of full-thickness tears of the supraspinatus: does the tendon really heal?

BACKGROUND: Good functional results have been reported for arthroscopic repair of rotator cuff tears, but the rate of tendon-to-bone healing is still unknown. Our hypothesis was that arthroscopic repair of full-thickness supraspinatus tears achieves a rate of complete tendon healing equivalent to those reported in the literature with open or mini-open techniques. METHODS: Sixty-five consecutive shoulders with a chronic full-thickness supraspinatus tear were repaired arthroscopically in sixty-five patients with use of a tension-band suture technique. Patients ranged in age from twenty-nine to seventy-nine years. The average duration of follow-up was twenty-nine months. Fifty-one patients (fifty-one shoulders) had a computed tomographic arthrogram, and fourteen had a magnetic resonance imaging scan, performed between six months and three years after surgery. All patients were assessed with regard to function and the strength of the shoulder elevation. RESULTS: The rotator cuff was completely healed and watertight in forty-six (71%) of the sixty-five patients and was partially healed in three. Although the supraspinatus tendon did not heal to the tuberosity in sixteen shoulders, the size of the persistent defect was smaller than the initial tear in fifteen. Sixty-two of the sixty-five patients were satisfied with the result. The Constant score improved from an average (and standard deviation) of 51.6 +/- 10.6 points preoperatively to 83.8 +/- 10.3 points at the time of the last follow-up evaluation (p < 0.001), and the average University of California at Los Angeles score improved from 11.5 +/- 1.1 to 32.3 +/- 1.3 (p < 0.001). The average strength of the shoulder elevation was significantly better (p = 0.001) when the tendon had healed (7.3 +/- 2.9 kg) than when it had not (4.7 +/- 1.9 kg). Factors that were negatively associated with tendon healing were increasing age and associated delamination of the subscapularis or infraspinatus tendon. Only ten (43%) of twenty-three patients over the age of sixty-five years had completely healed tendons (p < 0.001). CONCLUSIONS: Arthroscopic repair of an isolated supraspinatus detachment commonly leads to complete tendon healing. The absence of healing of the repaired rotator cuff is associated with inferior strength. Patients over the age of sixty-five years (p = 0.001) and patients with associated delamination of the subscapularis and/or the infraspinatus (p = 0.02) have significantly lower rates of healing.

Grammont reverse prosthesis: design, rationale, and biomechanics.

Combined destruction of the rotator cuff and the glenohumeral joint may lead to a painful and pseudo-paralyzed shoulder. In this situation a nonconstrained shoulder prosthesis yields a limited functional result or may even be contraindicated. Previous constrained prostheses (ball-and-socket or reverse ball-and-socket designs) have failed because their center of rotation remained lateral to the scapula, which limited motion and produced excessive torque on the glenoid component, leading to early loosening. The reverse prosthesis designed by Paul Grammont, unlike any previous reverse ball-and-socket design, has introduced 2 major innovations that have led to its success: (1) a large glenoid hemisphere with no neck and (2) a small humeral cup almost horizontally oriented with a nonanatomic inclination of 155 degrees, covering less than half of the glenosphere. This design medializes and stabilizes the center of rotation, minimizes torque on the glenoid component, and helps in recruiting more fibers of the anterior and posterior deltoid to act as abductors. Furthermore, the humerus is lowered relative to the acromion, restoring and even increasing deltoid tension. The Grammont reverse prosthesis imposes a new biomechanical environment for the deltoid muscle to act, thus allowing it to compensate for the deficient rotator cuff muscles. The clinical experience does live up to the biomechanical concept: the reverse prosthesis restores active elevation above 90 degrees in patients with a cuff-deficient shoulder. However, external rotation often remains limited, particularly in patients with an absent or fat-infiltrated teres minor. Internal rotation is also rarely restored after a reverse prosthesis. Failure to restore sufficient tension in the deltoid may result in prosthetic instability. The design does appear to protect against early loosening of the glenoid component, but impingement of the humeral cup on the scapular neck can lead to scapular notching and polyethylene wear. This is a cause for concern, especially as the notch is often more extensive than can be explained by impingement alone. Bony lysis of the scapula may also be related to a polyethylene granuloma. Further follow-up is required to ensure that loosening does not become a problem in the long term, and it has been recommended to limit its use to elderly patients, arguably those aged over 70 years. Despite these concerns, the reverse prosthesis, based on the biomechanical Grammont concept, offers a true surgical option in several situations where only limited possibilities were previously available: cuff tear arthrosis, persistent shoulder pseudo-paralysis due to a massive and irreparable cuff tear, severe fracture sequelae, prosthetic revision in a cuff-deficient shoulder, and tumor surgery. Finally, surgeons must be aware that results are less predictable and complication/revision rates are higher in revision surgery.