Treatment methods for shoulder pain

The function of the shoulder joint | Symptoms | Treatment methods | Consultation

HOW DOES THE SHOULDER JOINT FUNCTION?

The shoulder is the most mobile joint in the human body. This mobility demands a special anatomy and highly functional cooperation between different muscles and stabilisers.

The static stabilisers include the glenoid cavity (joint capsule), ligaments and the labrum, a ring of cartilage that expands the joint. The dynamic stabilisers include four muscles, the tendons of which surround the head of the humerus to form the rotator cuff. They hold the head of the humerus tightly within the joint during movement of the arm, ensuring stability. The shoulder joint functions as a ball and socket joint. In contrast to the hip, which is also a ball and socket joint, there is very little bony guidance at the shoulder. This guarantees the greatest mobility. Also different to the hip, the head of the humerus is not embedded within the glenoid cavity but only "leans" against it. For the joint to hold and the head to be guided stably within the socket requires soft tissues to take over this role.

The shoulder has had an amazing evolutionary history. Since humans have been walking upright, we have no longer needed it as a load-bearing joint. The arm then received important new tasks: it had to be able to position the hand - our most important tool - in space so that we can use it where it is needed. The shoulder therefore has a very high demand for mobility. The muscles, which previously only served to move the paws forwards, now had to be able to lift the entire arm.

The first special feature of the shoulder joint is that it is functionally (i.e. to fulfil the function of the arm) not just one joint, but four. Firstly, the joint between the humerus and the scapula, the glenohumeral joint; secondly, the joint between the clavicle and the acromion, the acromioclavicular joint; thirdly, between the clavicle and sternum, the sternoclavicular joint. Lastly, the joint between the scapula and the thorax, the scapulothoracic joint: this is not formed of joint surfaces, but of the muscular attachments of the scapula. A total of 11 muscles arise from the scapula. Most of these act to hold the scapula on the back and move it.

Glenohumeral joint

When we talk about the shoulder joint, we mostly refer to the glenohumeral joint between the head of the humerus and scapula. This joint is also enormously mobile: it is responsible for around two thirds of the entire range of motion of the arm. It is constructed as a ball and socket joint. However, to maintain mobility, the joint socket cannot surround the ball, as in the hip. The glenoid cavity has only around a quarter of the joint surface compared with the ball. It is also not very deep. It is a little like a golf ball on a tee. There is therefore very little bony guidance within this joint compared to the hip; the joint has no bony stability. Stabilisation must therefore come from various soft tissues. These include the static stabilisers, including the joint capsule, ligaments (reinforcements of the capsule) and the labrum. The latter acts to increase the joint surface and drags on the head of the humerus such that a vacuum forms. This is very similar to the way a suction cup works on a fridge door.

The dynamic – or mobile – stabilisers include the muscles of the rotator cuff. These are four muscles and their tendons that pass from the scapula to the head of the humerus and surround this on its anterior and posterior sides, as well as above so that it resembles the open sleeve of a shirt. Hence the name: (rotator) cuff. These four extremely important muscles act to keep the head of the humerus within the joint during movement and thus enable the range of movement. The two posterior muscles also act to rotate the arm externally. If the large deltoid muscle, which passes from the acromion to the humerus, wants to move the arm, it pulls it upwards. The head of the humerus would then glide upwards and strike the acromion, which would be painful, were it not for the rotator cuff which holds the head of the humerus within the joint and thus enables it to rotate within the joint without it coming into contact with the acromion.

AC and SC joints

The acromioclavicular (or AC) joint is at the roof of the joint, formed by the acromion and the clavicle. Just as with the joint between the sternum and clavicle (sternoclavicular = SC joint), it is somewhat individual as in many people it is not vertical, but slanted. Furthermore, each joint has its own ligaments. The clavicle acts as a support for the shoulder, especially when the arm is raised above the horizontal. This places considerable pressure on the small AC joint. It is therefore degraded in many people and leads to osteoarthritis. Although the SC joint is exposed to the same pressure stresses, it is affected by osteoarthritis surprisingly rarely. This may be because the rotation movements are much smaller at the SC joint than the AC. These act like a pepper grinder on the small ligament in the AC joint.

Scapulothoracic joint

Fully underestimated, but of considerable importance for movement of the arm is the mobility of the scapula (shoulder blade) on the back. Seven muscles attach the scapula to the ribcage to enable its great mobility. When the arm is raised, we move roughly up to the horizontal within the shoulder joint, then the scapula turns upwards. However, the scapula is also heavily involved in moving the arm forwards or backwards. When this movement is disrupted, there is often a hardening of the muscles in the area of the back and scapula; this can be very painful.

Neurology – control of the joint

Apart from the skeleton and muscles, successful movement also requires control: neurology. The brain and cerebellum transmit the impulses for movement to the spinal cord. Around the level of the lower cervical vertebrae, the neurons exit the spinal cord as spinal roots and enter the brachial plexus, where they group into the actual nerves. From there the nerves pass to their various target muscles. These are responsible for controlling the fine network of muscles that move the shoulder and, with it, the arm. Blockage or injury to the individual nerves leads to paralyses of the corresponding muscles and therefore to disrupted function of the shoulder. The impairment can be more or less serious depending on which muscle is affected.

WHAT ARE THE MOST COMMON SHOULDER PROBLEMS?

Osteoarthritis is the most common cause of persistent shoulder problems. There are various reasons for this: damage to the rotator cuff, instability, overexertion, following an accident or infection. Read more about how osteoarthritis develops.

WHAT THERAPIES ARE AVAILABLE?

There is a fundamental differentiation into conservative and surgical treatment methods. Before surgery is undertaken and, depending on the problem/cause, an initial attempt is always made to exhaust the conservative treatment methods, such as medications, physiotherapy or infiltrations into the joint. If these are of no benefit, the pain is unbearable and the quality of life is severely impaired, arthroscopy or joint replacement surgery may be options. You can find more information on the various treatment options here.

WE WILL BE PLEASED TO GIVE YOU A PRIVATE CONSULTATION

Our doctors have extensive experience and expertise in joint and sport surgery. Dr. med. Gregor Szöllösy is a certified shoulder and elbow expert with extensive know-how in the area of artificial shoulder joints. He is also a lecturer on the Basel Elbow Surgery Course.