shoulder injuries rotator cuff impingement; Pro-Am Sports Injury Clinic

Rotator cuff impingement

Normal shoulder function is essential for many sports and activities. Injury can cause great impairment of quality of life. Due to the range of motion the shoulder can achieve it requires enormous stability and correct timing of muscle activation to work efficiently.

Anatomy - Video

The shoulder is considered a ball-in-socket joint. The surface area of the glenoid is much smaller than that of the contacting humeral head (25-30%). The cartilaginous labrum provides much of the socket function and increases the surface area of contact for the humeral head. Together, these components provide a great amount of shoulder mobility with limited stability. Shoulder stabilizers can be grossly categorized as static or dynamic.

Static stabilizers include the bony structures, labrum, GH ligaments, and joint capsule. Unlike the hip joint, the bony articulation of the shoulder offers little stability. This is due to the limited contact area of the glenoid with the humeral head. The labrum is a fibrous structure that attaches to the glenoid to increase the contact area and deepen the socket of the glenoid up to 50%, forming a concave surface. Three GH ligaments exist, as follows: superior, middle, and inferior. The inferior GH ligament is the most important for shoulder stability and has 3 components, as follows: anterior, inferior, and posterior.

Dynamic stabilizers include the rotator and scapular stabilizers (i.e., teres major, rhomboids, serratus anterior, trapezius, levator scapula). The rotator cuff is comprised of 4 muscles, as follows: the supraspinatus, infraspinatus, subscapularis, and teres minor. The supraspinatus is the principle supporting muscle of the shoulder. The primary function of the rotator cuff muscles is to stabilize the GH joint so that the larger shoulder movers (e.g., deltoid, latissimus dorsi) can carry out their function without significant motion of the humeral head on the glenoid.

The Rotator Cuff

The rotator cuff muscles are associated and assist with some shoulder motion; however, their main function is to provide stability to the joint by compressing the humeral head on the glenoid. The supraspinatus assists in shoulder abduction by maintaining the humeral head centered on the glenoid, with the middle deltoid acting as the primary mover. These muscles act as force couples because they work synergistically to carry out a particular movement. Electromyography (EMG) studies have demonstrated a high degree of supraspinatus activity during the initial 30° of abduction. The supraspinatus has to fire strongly to stabilize the GH joint as the deltoid abducts the arm.

The infraspinatus and teres minor muscles assist in external rotation of the shoulder and also provide an inferior pull upon the humeral head, assisting in its centering during overhead activity. The subscapularis muscle participates in this centering but also acts with the pectoralis muscles and latissimus dorsi as an internal rotator of the shoulder, serving as the main internal rotators of the shoulder.

Weakness or insufficiency of the rotator cuff muscles results in increasing demands on the static stabilizers. If these demands are long term or recurrent, static stabilizers may begin to fail. This can result in stretching or attenuation of the capsule, which results in even greater shoulder laxity and greater demands on the already weak rotator cuff muscles. Humeral head migration may occur with capsule laxity and result in rotator cuff impingement and pain. Pain may inhibit rotator cuff muscle firing, leading to disuse and further weakening of the dynamic stabilizers with greater demands placed on the static stabilizers. Increased humeral head translation can also lead to shearing and injury to the glenoid labrum. Rotator cuff impingement, tendinitis, and labral pathology are commonly encountered injury patterns in athletes and workers who perform overhead motions. Focusing solely on the static stabilizers in treatment neglects the dynamic structures that probably initiate and perpetuate the cycle

Assessing the Shoulder

When assessing the shoulder there can be a number of structures causing pain so I tend to narrow the problems down in to the following: -

Rotator cuff disorders, includes; impingement, subacromial bursitis, tendinosus, painful arc syndrome, and partial or full thickness tears of the rotator cuff.
Biceps tendinosus or rupture and calcify
Frozen Shoulder (Adhesive Capsulitis)
Instabilities, includes; acute and recurrent subluxation, dislocation and labral injuries
AC joint and SC Joint

Rotator cuff injuries can be muscle strains, tears, tendinopathy, tightening and focal thickening of the muscle bellies. A common complaint is impingement due to the muscles been unable to counter balance the deltoid due to weakness and/or disturbed scapula humeral rhythm.

Pain felt in the biceps region can be referred from the rotator cuff. It is important to differentiate between a true biceps injury and rotator cuff dysfunction. They can co-exist together.

Shoulder instability is another common cause of shoulder pain and can become the cause of rotator cuff injuries or add to even further rotator cuff demand. It can result from a sprain to the capsule and ligaments, secondary impingement (loss of scapulohumeral rhythm), as well as subluxation/dislocation. This can cause glenoid labral tears. Instability can be obvious in patients with recurrent dislocation but instability can cause minor symptoms such as mild impingement.

It is important to assess the AC Joint which is just above the shoulder joint, it is usually injured by falling onto an outstretched arm and onto the shoulder (compression). Pain can also be referred from the neck and upper back.

A patient with chronic shoulder problems will have a number of factors contributing to the problem, such as cervical/thoracic joint dysfunction, soft tissue tightness and trigger points, in addition to the primary shoulder joint abnormalities such as rotator cuff tendinopathy and/or instability.

Normal shoulder motion

The shoulder complex is comprised of several joints, including the sternoclavicular joint, Acromioclavicular joint, glenohumeral (GH) joint, and scapulathoracic (ST) joint. These articulations work together to carry out normal shoulder motion. The majority of motion occurs at the GH and ST joints. A rhythm between these 2 areas of motion has been described. The GH–to–ST motion ratio of total shoulder motion is 2:1, i.e., 180° of abduction, consisting of 120° of GH motion and 60° of ST motion. The 2:1 ratio is an average over the entire arc of motion. In the beginning of arm motion the GH motion predominates for the humerus to reach further than 60 degrees the scapula must start to move. Scapula motion will stop around 120 degrees leaving the GH joint free to finish the full movement. Impingement syndrome is usually felt between 60-120 degrees of abduction (painful arc).

The importance of the scapula in normal shoulder motion cannot be overstated. The scapula, with the glenoid as its contact point, forms the platform for humeral head articulation and motion. A stable platform is essential for normal shoulder biomechanics in everyday activities and is crucial for high-demand activities (e.g., overhead sports or work). The scapula must glide along the chest wall as it protracts and retracts during normal shoulder movements. Scapular position can inform the therapist of dysfunction, I.E. winging of the scapula results in glenoid tilting forward, which results in a functional elevation of the humeral head and impingement of the rotator cuff. In addition, without scapular motion, the origin and insertion of the deltoid approximate each other, resulting in a decreased optimal length-tension relationship and a decrease in force as the shoulder abducts. Normal scapular motion allows the deltoid to maintain its length-tension relationship and generate adequate force.

The next picture (to the left) shows a typical posture of someone who is suffering from shoulder impingement. It is important to remember that impingement is a symptom not a diagnosis. The true cause of the impingement has to be found. There is likely to be more than one.

When weakness of the stabilisers has been present for a while the strain will be put onto other muscles for example the upper traps, latissimus dorsi and the pectoral minor. This can be observed in the clients posture see diagram 4,5 and 6. Figure 4 shows shortening of the latissimus dorsi on the right side and the upper trapezius is tight (compensates for weakness in lower and mid traps), you can also see scapula winging (weakness of serratus anterior or lower traps), the middle and lower traps have lost bulk. In figure 5 you can see a forward head position (tight upper traps) and an anterior tilt on the scapula with a forward position of the humerus (general weakness of scapula and rotator cuff muscles and possible ligament laxity). Picture 6 shows a medially rotated shoulder on the right (tight pec minor, weakness of lateral rotators) as well as the neck leaning to the right showing muscle shortening of upper traps, you can see the right lean again from latissimus dorsi. This muscle imbalance happen as the global muscles upper traps, latissimus dorsi and pec minor compensate for the local muscles of the scapula and rotator cuff weakness. Taken from SportEx medicine.

Rotator Cuff Injuries symptoms and treatments

tendonitis, strains, tears

A tear of the rotator cuff muscles usually occurs when there is already degeneration. It is rare for it to occur as an isolated injury but would occur if you were to fall on an out stretched arm or during heavy pulling and pushing activities.

Chronic tears result from repeated micro trauma that impinge on the supraspinatus tendon just proximal to the greater trochanter. Impingement is a common symptom and is caused by the force overload to the rotator cuff that mainly occurs during abduction, forward flexion and medial rotation cycles. Sports typically affected are those of a throwing nature, above head activities (tennis serve) and frontcrawl/butterfly swimmers.

Symptoms are felt on the anterior lateral aspect of the shoulder and are described as a deep dull ache. Pain will increase with activity which may cause sharp pain on certain movements (above the head). It maybe painful to sleep on that side. Pain is usually palpated in the subacromial space (just below the end of the clavicle). If a tear is present the muscle will atrophy quickly. Movements affected include any overhead, there may be a limitation of abduction and possible internal rotation (hand behind back). The longer the problem is untreated the upper traps muscle can become very tight and painful. If movements are limited but do not cause discomfort than a full tear must be suspected.

Factors which may contribute to impingement include; - excessive amount of overhead movement (overuse), limited subacromial space, thickness of the supraspinatus and biceps brachii tendons, lack of flexibility and supraspinatus and biceps brachii, weakness of the posterior cuff (infraspinatus, teres minor), tightness of the posterior shoulder (capsule), hyper mobility of joint (instability), imbalance in muscle strength, co-ordination, and endurance and scapula muscles, shape of the acromion, training devices (hand paddles).

Tendonitis is inflammation of the rotator cuff tendons which can lead to a tear if not treated.

Rehabilitation of the shoulder

Rehabilitation of shoulder injuries should look at the whole area no matter how minor. Without scapula stabilization the rotator cuff muscles can't work efficiently. Without the rotator cuff you have no stability of the humerus. Proprioception work is also vital. It can be a hard, long return to sport with shoulder injuries as the rehabilitation process is quite complex. Even Tim Henman had to take a time out of tennis and hit the gym to combat a recurrent shoulder problem.

Before any strengthening can begin the therapist needs to make sure the patient knows how to reset the scapula and humerus. This may take some practice but the scapula and humerus must be placed in the correct neutral position otherwise the problem is not going to improve. Taping can be used to help.

I have not given a programme to follow for shoulder rehabilitation because posture and correct alignment are very important, this can only be achieved with the help of an injury specialist. What I have done is show you some pictures of exercises that you can expect to see in some of my shoulder rehabilitation programmes.

A shoulder rehabilitation programme should include the following: -

Correction and re-education of scapula and humerus position

Scapula stability; may include seated row, press-up, reverse flies different angles.

Rotator cuff strengthening; supraspinatus strengthening, shoulder rotations

Proprioception: gym ball, catching, mirror matching

Sports Specific training

Prevention

Prevention is achieved by keeping the muscles balanced. Strengthening and Stretching are important. I have attached some videos and websites from about.com which show some of the main exercises which may prove helpful. These are just for information only if you are interested further ask a professional to show you properly.

The rotators and muscle at the front of the shoulder can become very tight its important to stretch these. Video

Rotator cuff exercises - Article