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Common Shoulder Problems
Dr. Tom Crisp Fitness Network, Oct/Nov 96
Joints rely on a combination of factors for stability. In the knee it is mainly ligaments that provide this stability, while the hip joint is kept in place by the bone structure. Because of the functions the shoulder fulfils, it cannot have much bony stability and instead relies on muscles for its stability more than any other joint.
More importantly than this perhaps, is the fact that the shoulder is really a complex of joints that work together to produce amazing mobility. For the humerus to move well in relation to the scapula, the scapula must be positioned correctly in relation to the chest wall. So the control of scapular rotation is as important as control of the humeral head in the shoulder joint as far as effective movement is concerned.
So what goes wrong with the shoulder? The problems can be divided into three main groups: the instability problems, rotator cuff and subacromial problems, and scapular problems. Of course there are other sources of trouble and it is worth remembering that at least one out of every three patients attending my clinic complaining of shoulder pain have in fact a cervical or upper thoracic spine problem.
Many of the muscles that work the shoulder take origin from the spine and if there is an injury to the spine (even a minor ligament strain) this can affect the function of the muscles that are attached nearby. As a useful little tip, if you have trouble reversing the car it is likely that you have a minor neck problem, and any shoulder pain may be secondary.
Anatomy
The shoulder comprises a glenohumeral joint, (between the head of the humerus and the glenoid cavity of the scapula) the acromioclavicular and sternoclavicular joints (at either end of the collar bone or clavicle) and the scapulothoracic joint (the articulation that allows the scapula to rotate, protract and retract). Some clinicians add to this list the subacromial space in which there is a lubricating bursa which separates the humeral head from the bony structures immediately above (i.e. the acromium part of the scapula and the coracoacromial ligament) and which acts almost as another joint.
Plus, as mentioned, it is sometimes useful to consider the articulations between ribs and vertebrae and between one vertebra and the next, since problems with these joints can affect the function of shoulder muscles.
The humeral head is kept in place in the very shallow glenoid by a series of glenohumeral ligaments, and by the rotator cuff muscles (subscapularis, infraspinatus, supraspinatus and teres minor). The major movers of the shoulder (deltoid, pectoralis, latissimus dorsi, etc.) are all attached some way from the axis of rotation of the humeral head and all tend to pull the shoulder out of joint. These need to be balanced by the rotator cuff muscles to keep the humerus in place when it moves.
The clavicle provides an important brace for the scapula, connecting it to the rest of the skeleton, yet the joints at either end rotate as well as hinge and are easily injured, as in a fall on to the point of the shoulder. Loss of movement at either end will reduce scapular movements.
Rotator cuff problems:
Strain of the rotator cuff muscles is common especially in the over-40s, when the strength of the cuff relative to the larger muscles diminishes. This leads to more movement of the humeral head and impingement (squashing) of the muscles against the bony structures above, especially in overhead activities such as throwing when rotational velocities of up to 600 degrees per second can be reached in the shoulder joints. This can also inflame the bursa (causing a bursitis) and it is often difficult to decide exactly where the primary problem is: the experts tend to refer to subacromial problems without specifying whether it is the cuff or the bursa that is affected.
However, no matter what starts things off, the symptoms are of pain on throwing and during other overhead activities, even during something as simple as combing your hair, with pain often when lying on the affected side. The shoulder may also feel weak and click a lot. Strengthening of the cuff muscles will improve most of the problems, often with the help of anti-inflammatory physiotherapy or even cortisone injection. The latter should not be used without every effort to strengthen the cuff muscles.
Shoulder instability:
Shoulder instability can arise either because of acute trauma such as a dislocation, from repeated ‘microtrauma’ as with a professional thrower who puts excessive strain on the stabilisers repeatedly over a prolonged period, or because of congenital ligamentous laxity. All three of these are relatively common in the young athlete and all result in loose ligaments.
In the area of aerobics and weight training, the last is the most common cause, though of course, an athlete having dislocated the shoulder may turn to other forms of exercise to keep fit. It is not unusual for exercisers to present as a rotator cuff problem because the instability has interfered with the function of the stabilising muscles. They may therefore present not only with clicking, obvious movement and giving of the shoulder but pain on overhead activities as well. Muscular rehabilitation is the mainstay of treatment for most, though some require surgical tightening of the ligaments.
A significant group of shoulder pain sufferers are those doing a lot of weight training to strengthen specific muscles and thus causing imbalance whether between the cuff and the larger muscles, the anterior internal rotators (including pectoralis) and the posterior external rotators (such as infraspinatus) or between the anterior muscles and the scapular rotators (trapezius, the rhomboids, levator scapulae and serratus anterior).
They will present with pain in the shoulder on certain exercises, especially those that move the arm above the head. In this position the space above the humeral head is narrowest and impingement is likely. The treatment here is obvious: strengthen the stabilisers as much as the movers.
Scapular problems:
The need for scapular stabilisation is often forgotten and this can lead to just as big a loss of function of the shoulder complex as a whole as a cuff injury. If the scapula is not properly positioned there will be extra strain on the glenohumeral joint and the possibility of strain to the cuff and the bursa as a secondary problem. Trapezius is often blamed for problems as it is an essential muscle for scapular control, but serratus anterior has been shown to be at least as important in the action of throwing. So muscular imbalance around the scapula can be just as much a problem as imbalance between cuff and other shoulder muscles.
Rehabilitation:
Muscular rehabilitation is the most important part of treating shoulder problems.
It is often useful to start strengthening the cuff muscles isometrically, avoiding the movement of their tendons in a small, perhaps inflamed space. This can be done using the other arm or a wall as resistance and performing an increasing number of 10 second contractions of each in the three main directions.
Supraspinatus:
Initiates abduction, so with the arm at the side try to abduct straight out to the side against resistance. Infraspinatus and teres minor externally rotate, so with the arm at the side and the elbow flexed to 90 degrees try to rotate outwards against the resistance. Subscapularis internally rotates and this can be strengthened in the same position as for external rotation above, but rotating inwards against resistance.
As the symptoms improve, these actions can be performed dynamically (with dynaband’, for example initially) with the arm at the side but progressing to increasing degrees of abduction (the shoulder is at its most vulnerable in 90 degrees of abduction and external rotation).
For the scapular rotators, shoulder shrugging and rolling (with the arms by the side) and later rowing, upright rowing and press-ups will be useful. The proprioception (sense of position) will be improved by balancing on one arm (a tripod similar to a press-up position with two feet and one hand on the ground and a straight back).
Prevention of injury
Clearly it is better to prevent injury and by building rotator cuff and scapular rotator exercises into an exercise regime the shoulder will be protected. Rotation of the humerus in neutral (arm by the side) in flexion (arm out in front of the body) and in abduction (out to the side) will help and suitable exercises can be built into an aerobics class or by using dumbbells in a weights session. Many sportsmen and women ignore the risk of shoulder injury and stress the shoulder with no adequate preparation.
Throwers not only stress the cuff muscles but also stretch the anterior capsule. To balance this and avoid anterior instability, stretching of the posterior capsule is necessary and can easily be done by pulling the arm horizontally across the chest and holding as for any other stretch. For weightlifters and bodybuilders, it is necessary to strengthen the stabilisers as well as the more desirable and obvious muscles, to avoid future debilitating shoulder problems.