Rotator Cuff tear - Does size and Location of the tear matter?
Rotator cuff is formed by 4 tendons ( supraspinatus, Infraspinatus, Teres Minor and Subscapularis) which form an anatomical unit rather than having discrete attachments.
The main functions of the rotator cuff is to centralize the humeral head during shoulder movements, countering the forces of Deltoid and Latissimus Dorsi muscles.
Superiorly it is separated from the acromion by a thin layer of subacromial bursa which extend under the Deltoid muscle as subdeltoid bursa. On the inferior aspect the Rotator cuff ( supraspinatus) is separated from the shoulder joint by the capsule of the joint.
Rotator cuff tear
Rotator cuff tear have been classified according to the size (depth) of the tear into:
Small (0-1 cm), Medium (1-3 cm), Large ( 3-5 cm) and Massive ( >5cm). The normal depth of the Rotator cuff is about 10 cm. Some classification term massive tears to the ones which involve 2 or more tendons. 4% of the patients with massive tears develop Rotator cuff arthropathy.
Further they are grouped into Grade 1 tears (<25% thickness), Grade 2 tears ( 25-50% thickness) and Grade 3 tears ( >50% thickness).
On the basis of the shape, the tear can be crescent shaped, L-shaped, U-shaped and massive-immobile tear. The shape of the tear determines the type of surgical repair techniques. Location wise, the tears can be intrasubstance, articular surface and Bursal surface tears
The goals of treatment for rotator cuff tear is symptom management, regaining shoulder range of motion and strength. Signs of symptomatic impingement without rotator cuff tear offer good prognosis with conservative treatment based around physical therapy.
Tears can remain asymptomatic but both partial and full thickness tears don't have a great likelihood of healing by themselves. Different studies have indicated that the progression in Partial thickness tear can vary from 8-81% of the partial tears. Full thickness tears however progress inadvertently. Age more than 60years, fatty infiltration and big tear size are associated with increased risk of tear progression.
New symptoms with existing asymptomatic tears suggest tear progression. Progression of supraspinatus tear anteriorly to the coracoacromial ligament and subscapularis tendon is associated with poor prognosis. Similarly associated long head of biceps pathology or tear progression to involve the Biceps brachii tendon is associated with poor prognosis and outcomes of the treatment.
In comparison to the articular surface, tears on the bursal side are less common in occurrence and being symptomatic. However the risk of progression and being resistant to conservative treatment is higher with the bursal sides of tears. Associated impingement, bursitis contribute to the symptoms related to rotator cuff tendinopathy and tear.
Outcomes even with surgery are better with small tear size, with large tears are difficult to repair and have high re-tear risks. Tendon rupture medial to Glenoid margin are virtually considered to be irreparable. The retear rates after surgery is about 18-20% in general and this increases to 37-94% after repair of a massive tear. Interestingly, despite retear, the patient reports less symptoms related to re-tear. Increased fatty degeneration in the rotator cuff muscle has a negative predictive value after the surgery for torn rotator cuff tendon(s). Surgery has not been seen to be better than physical therapy in atraumatic partial thickness or atraumatic full thickness tears.