The rotator cuff is made up of four tendons (supraspinatus, infraspinatus, subscapularis, and teres minor) that attach to the head of the humerus. Tears occur most commonly in the supraspinatus tendon. The purpose of the tendons is to assist in shoulder movements such as reaching away from your side, lifting your arm overhead, in rotating the shoulder, and helps to stabilize the shoulder to prevent it from dislocating.
Mechanism of Injury:
A fall on the outstretched arm is the most common injury mechanism that causes a tear of the rotator cuff. Tears may also occur as a result of a fall onto the shoulder, a dislocation of the shoulder, a motor vehicle accident, or a sudden force applied to the shoulder such as lifting heavy objects. Tears may also occur due to the aging process which leads to degeneration of the rotator cuff tendon(s) and eventually may cause partial or full thickness tearing. Bone spurs that cause impingment (friction or compression) on the rotator cuff tissue also commonly contribute to eventual tearing. Repetitive overhead stress on the shoulder also can cause tearing in athletes especially in baseball players, softball players, body builders, swimmers, tennis players, and volleyball players. A traumatic event can cause a tear at any age but degenerative or atraumatic tears usually occur later in life often during or after the 5thdecade.
Shoulder pain is the most common presenting symptom especially when moving the arm away from your side (abduction), reaching in front of you (forward flexion), reaching above shoulder height, reaching behind your back, and rotational movements. Pain while sleeping is a very common complaint as well. The location of pain can be anywhere around the shoulder but classic rotator cuff pain usually occurs along the side of the shoulder and can radiate down the side of the arm (top third of humerus) but not usually beyond the midpoint of the humerus. Pain that radiates to the elbow or past it is often referred nerve pain from a pinched nerve in the neck. Shoulder impingement with bursitis (inflammation) and rotator cuff tears present with similar complaints and exam findings. Weakness is also a common complaint that typically is noticeable when trying to hold objects with your arm away from your body such as reaching into cabinets or lifting weights. Not all rotator cuff tears will cause weakness as many people will have normal strength unless they have a larger tear.
Both X-ray and MRI are usually necessary in order to diagnose a rotator cuff tear. X-rays will often demonstrate a bone spur or a downsloping acromion (the front part of the shoulder blade) and occasionally a cyst in the bone near the rotator cuff attachment. X-rays also are helpful in identifying any associated arthritis in the shoulder. An MRI will show the entire spectrum of rotator cuff pathology including degeneration (tendinosis), partial tearing, and full thickness tearing. MRI studies on asymptomatic patients have demonstrated that rotator cuff tears are quite common and may be present but may not cause pain or weakness. MRI is also valuable in identifying commonly associated findings such as a biceps tendon tear, labrum tears, and bursitis. Ultrasound is also helpful when evaluating for a rotator cuff tear but is very much user dependent and is not as accurate when identifying associated pathology in the shoulder.
Rotator cuff tears can be successfully treated with activity modification such as avoidance of aggravating activities, physical therapy, and injections. The purpose of physical therapy is to strengthen the rotator cuff muscles and improve the mechanics of the scapula (shoulder blade) which in combination can create more space for the rotator cuff to move beneath the acromion so that it is no longer getting compressed or pinched. Physical therapy can take weeks or even months to determine if it will be effective. A home exercise program is a very important part of the therapy process. A variety of injections also exist for treating rotator cuff tears. A steroid (cortisone) injection is often performed to reduce any inflammation of the bursa into quickly reduce pain in hopes of a more effective rehabilitation program. If the majority of the shoulder pain is coming from the bursitis and impingement, then the steroid injection may resolve the issue long-term. If there is a rotator cuff tear, the steroid injection may be short-lived ranging from days to months. Other injections that are becoming popular for treating partial thickness tears or small full thickness tears include platelet rich plasma (PRP), stem cells, and amnion. These injections can be used in hopes of avoiding surgery or can be utilized in surgery to potentially enhance or expedite the healing of the rotator cuff repair. Surgery is usually necessary after failure of a conservative treatment plan or in the case of larger full thickness tears. Many partial thickness and small tears can be treated conservatively. The surgery is typically performed arthroscopically using 3 to 5 small incisions and is usually done as outpatient surgery. The anesthesiologist will usually administer general anesthesia and a scalene nerve block (an injection between neck and the shoulder) to help reduce the post-surgical pain. The surgery usually consists of placing suture anchors into the bone of the humerus to reattach the torn rotator cuff tendon(s). A sling will typically be used for 4-6 weeks after surgery depending on the size of the tear and the tissue quality. It is recommended to avoid reaching away from your side for approximately 6-8weeks. Restrictions are usually lifted between 4-6 months but full recovery likely occurs between 12-18 months.