The rotator cuff comprises four muscles that all arise on the scapula (shoulder blade) and insert into the proximal humerus (top of the arm bone). These muscles are important for controlling matched motion of the ball and socket joint during shoulder movement, particularly raising and lowering the shoulder and rotating the arm. The tendons of the rotator cuff muscles are broad and flat and form a cloak that covers the humeral head.
The subscapularis muscle is the largest of the rotator cuff muscles and it lies on the front of your shoulder blade. It acts to rotate the arm inwards as well as contributing to stability of the shoulder joint.
The supraspinatus muscle is the tendon most commonly affected by degeneration and tearing. The supraspinatus helps you raise your arm to the side away from your body.
The infraspinatus and teres minor both arise from the back of your shoulder blade and insert onto the back of the humeral head. These muscles help your arm to rotate outwards. The infraspinatus also contributes to the stability of the shoulder joint.
As we age, our rotator cuff tendons degrade and weaken. This degenerative process sometimes causes pain, but for many of us this is a silent process. Once weakened, the cuff tendons may rupture (rotator cuff tear) with minor force and often even with no recalled injury. The supraspinatus tendon, which inserts right on the top of the head of the humerus, is the most commonly torn tendon.
The rotator cuff tendons tear at their insertion into the humerus. If a tear in the tendon goes through the full depth of the tendon then it is called a ‘full-thickness tear’. If the damage involves only some of the thickness, it is termed a ‘partial-thickness tear’. Both can be painful and, because of this pain, impair function. Full thickness tears tend to cause more significant weakness, as the connection between the muscle’s force and the bone is interrupted. The first image below shows a normal supraspinatus tendon (A) as it inserts onto the humeral head (B). The next two views show a medium-sized rotator cuff tear. note how the tendon has peeled off from its insertion on the humerus, leaving exposed bone
Arthrosopic view from within shoulder joint - (A=Supraspinatus. B=Humeral head)
Same view in pt with rotator cuff tear. (A=rotator cuff tendon. B = humeral head. C= view t
hrough the tear to the subacromial space)
Arthroscopic view of the same rotator cuff tear from the subacromial space. (A=rotator cuff tendon.
B = exposed bone on humerus where tendon should be inserting. C= visible cartilage on humeral head seen through tear)
Small rotator cuff tears:
These may be completely asymptomatic. Those who do have pain often describe a gradual onset of a deep ache made worse with arm movements away from the body. Patients point to the upper outer arm as the site of the aching. Often it becomes hard to lie on the affected side.
Symptoms are often very similar to shoulder impingement.
Larger rotator cuff tears
The symptoms of pain are similar to those for a small tear, but as the tearing of the rotator cuff becomes larger, patients start to notice more weakness. This is particularly when using the arm away from your body or up in the air (e.g. reaching up to shelves).
Often patients use their other arm to help raise the weak affected arm. Sometimes patients have shoulder stiffness as well as weakness.
Rotator cuff tears are rare below 45 years old. To some degree, rotator cuff disease is a feature of ageing: a third of over-65 year olds will have some kind rotator cuff damage on MRI, but the majority of these people will have absolutely no symptoms. Most patients undergoing rotator cuff repair will be aged between 45 and 65.
Occasionally acute trauma can rip off healthy rotator cuff tendons, and shoulder dislocation in over 40 year olds has a 40% risk of tearing the rotator cuff.
Your symptoms and clinical examination findings are suggestive. Shoulder X-rays are useful to exclude other causes of pain. Normally the diagnosis will be confirmed by either ultrasound or MRI scans.
Often patients with partial thickness, or small tears, are concerned that their cuff tear might get worse if left un-repaired. This is a complex issue and the subject of on-going clinical research.
The evidence to date suggests that full thickness tears can slowly progress in size over time and that weakness is proportional to tear size. As tears get larger, the feasibility and success of tendon repair can also reduce. Chronic massive rotator cuff tears can cause arthritis, which, in some people, is bad enough to need joint replacement. However, the pace of this progression varies and it is not universal. Partial-thickness tears and small full-thickness tears may sometimes heal on their own.
Overall, the evidence does not mandate surgical repair of every tear on the basis of preventing future symptoms. Your surgeon will consider your needs, your symptoms, your functional limitations, and the nature of your rotator cuff damage before making any recommendations on treatment.
You might wish to monitor your shoulder function and come back if your symptoms deteriorate and some people want repeat scans (ultrasound or MRI) to see if the tear is progressing. As for most shoulder problems, your decision to undergo surgery should remain symptom-led, NOT scan-led.
Rest, activity modification, painkillers and anti-inflammatories are all firs- line options. You may well have tried these, but if not, they're a good first step.
Physiotherapy
This aims to restore balance and a smooth range of motion to your shoulder. Physios will guide you to strengthen your remaining intact rotator cuff muscles as well as focussing on your shoulder blade control and the large mover muscles of your shoulder that need to compensate for the weakness in the rotator cuff.
Steroid Injection (Cortisone)
This may have been offered by your GP already. The steroid injection can help reduce the bursitis (painful) element of rotator cuff disease. This can enable you to do your therapy more successfully. A single cortisone injection is extremely unlikely to exacerbate or cause a tear in the rotator cuff and it does not preclude future rotator cuff repair.
For degenerate rotator cuff tears (this is the majority of cuff tears), these non-operative measures should be tried before surgery is considered as several patients will improve enough to avoid surgery altogether.
If you continue to have troubling pain and/or weakness in your shoulder, despite good physiotherapy and an injection, then you may decide it’s time for a rotator cuff repair.
Repair of torn tendons is not always possible. Chronic, extensively torn tendons retract, the muscles wither away and the tendon material can become very fragile. These factors mean that your tendon sometimes simply cannot be fully repaired back onto the head of your humerus.
If surgery is being considered, you will normally be asked to have a scan (either Ultrasound or MRI). This gives a picture of the extent and likely reparability of your tendons. However, the final judgment on whether or not to repair is made after your tendons are both looked at and handled during your operation.
We also know from large studies that age is a strong predictor of healing of the rotator cuff tendons after surgery. In a 60 year old, the healing rate is 70%, but in a 70 year old with a large tear, the healing rate is only 40%.
If your tendon cannot be repaired, then other options can be employed to help you. The pain can often be improved by performing a Subacromial Decompression and, if the biceps tendon is involved, by doing a biceps tenotomy.
In patients over 65 with an irrepairable tear, disabling shoulder weakness can sometimes only be addressed by a reverse total shoulder replacement.