Shoulder Impingement

The Anatomy

The shoulder joint is made up of 3 bones and four different joints. The three bones are the humerus (upper arm bone), scapula (shoulder blade), and clavicle (collar bone). The four different joints that allow motion of the shoulder are the gleno-humeral joint, the acromioclavicular joint, the sternoclavicular joint, and the scapulothoracic joint. The joint directly involved in shoulder impingement is the acromioclavicular joint. The soft tissues involved in this condition are the subacromial bursa and the tendon of the supraspinatus muscle. The supraspinatus muscle is one of four muscles that make up the “rotator cuff”. The supraspinatus inserts into the greater tubercle on the top of the humerus and is the muscle involved with starting abduction of the arm, or lifting the arm up from at the side of your body. The supraspinatus is also involved in stabilization of the shoulder and is involved with resisting the downward gravitational force of the upper limb.

What Will You Experience?

The most common symptom that you will experience is pain and stiffness when raising your arm from the side or when lowering your arm to the side. You may also notice some swelling and irritation at the front of the shoulder joint. The symptoms usually start out mild and consist of a minor pain that is present at the front side of your shoulder joint, both with and without activity. It may progress then to a radiating pain that starts at the front of your shoulder joint and goes around to the outside of the arm. In addition, you will experience a sharp pain at the anterior side of the shoulder joint when you rapidly lift your arm up or rapidly let the arm down to the side. If the symptoms continue to progress, you could eventually feel this sharp pain even at rest, and you could experience weakness of the joint and decreased motion at the joint.

What Causes Shoulder Impingement?

Shoulder impingement can have many different original causes, but the mechanism behind the creation of pain is the same. This condition occurs when the acromion rubs on or “impinges” on the tendon of the supraspinatus or on the subacromial bursa. The space between the acromion and the bursa/tendon naturally becomes narrowed when a person lifts their arm up, but in abnormal cases the acromion impinges on these structures when the structures have become irritated and swollen. Irritation of the supraspinatus tendon is called tendinitis, and is usually caused by repetitive activities involving raising the arm up overhead. These repetitive activities can also cause inflammation of the bursa, or bursitis, where the bursa swells, thus decreasing the available space for the tendon to glide under the acromion.

Predisposing Factors

This condition is common in those involved in overhead sports such as volleyball, tennis, and swimming. It is also common in jobs that involve repetitive lifting or overhead motions, such as paper hanging, construction, or painting. In addition, this condition will more commonly occur if there is muscular imbalances of the muscles around the shoulder joint. Some of the most common muscles to be overactive is the upper trapezius, supraspinatus, and teres muscle groups. Some of the most common muscles to be underactive are the serratus anterior, inferior trapezius, and rhomboids (muscles involved in holding shoulders back). When these muscular imbalances occur, you don’t get proper stabilization of the scapulothoracic joint, therefore, abnormal motion of the glenohumeral joint, leading to repetitive irritation of the supraspinatus tendon.

What Can Lake Marion Chiropractic Do for You?

We will start with a complete assessment of the affected region, and in many cases, a comprehensive exam including assessing the cervical and thoracic regions. At Lake Marion Chiropractic Center, we understand that motions of the shoulder are dependent on proper muscular balance. With this condition, we will address the cervical and thoracic regions with chiropractic care and use advanced soft tissue techniques and corrective exercises for the soft tissue component of the condition. The end goal of our treatment plan is to return you to your normal activities of daily life as quickly as possible and develop a program for you that will prevent this condition from reoccurring.


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