Frozen Shoulder
Normal Anatomy
The shoulder joint is the second largest and most mobile joint in the human body and can be easily understood if divided into three layers. The first layer is the deepest layer made up of the bones that form the foundation. There are three bones consisting of the arm bone (humerus), the shoulder blade (scapula), and the collar bone (clavicle). There is a rounded head on top of the arm bone called the humeral head and a saucer shaped surface of the shoulder blade called the glenoid which complements the humeral head and together they form the shoulder joint. A layer of cartilage (blue area) covers the articular surfaces of the humeral head and glenoid to provide a cushioned surface which allows for smooth pain free shoulder motion. These three bones unite to form three joints, which are held together by the second layer which keeps the bones from separating during shoulder movement, allowing the bones to function as a unit.
The second layer is comprised of collagen tissue fibers that attach to the bones on both sides of the joint and form the joint capsule. Within the joint capsule, are dense cordlike collagen bundles that unite to form ligaments that in strategic locations further enhance the stability of the jointby resisting the forces created when we perform our routine daily activities.
The rim of the glenoid is encircled by a rubbery fibro-cartilage tissue called the labrum. The labrum is an anchor point for the ligaments of the shoulder capsule and the long head of the biceps tendon which attach to it creating a suction seal mechanism when the humeral head is in contact with the glenoid. This sealing mechanism adds another joint stabilizing effect. The three shoulder bones form there joints called the Glenohumeral (GH) joint, Acromioclavicular (AC) joint, and the sternoclavicular (SC) joint.
The third layer in the shoulder is the muscle layer. Within the muscle layer, there are several potential spaces that carry the arteries which supply the bodies’ nutrition and nerves that deliver the commands sent by the brain and spinal cord for muscle movement. The most important muscle group in the shoulder is called the rotator cuff muscles. Theyare comprised of four muscles that begin (originate) in the shoulder blades’ flat surfaces and attach to the arm bone in an area called the greater tuberosity footprint as a common tendon unit. The four tendons formed by the four rotator cuff muscles interdigitate with one another forming a protective mechanism that prevents rotator cuff tendon tears from quickly spreading once they occur. The interdigitation also allows the four muscles to work together as a unit, carefully balancing the shoulder joint against the forces of the deltoid muscle to create precise shoulder movement. The deltoid muscle, biceps muscle and other muscles about the shoulder that balance the shoulder blade, called the scapular stabilizers complete the shoulder muscles that make up the third layer and together create a dynamic balanced force which allows for normal function. The major function of the rotator cuff muscles is to provide shoulder joint dynamic stability, shoulder joint motion and strength to the arm.
Pathology
A Frozen shoulderalso called adhesive capsulitis is a condition presenting withshoulder stiffness and severe shoulder pain when shoulder motion is initiated. The tissue in the shoulder responsible for a frozen shoulder is in the second layer. The normal shoulder capsule and the corresponding ligaments which are normally loose with the armat the side, become tight at the extremes of shoulder motion which limits excessive shoulder motion thereby providing passive shoulder stability. In a frozen shoulder, on the other hand, the capsule/ligament complex is excessively tight, even with the arm at the side, losing the normally loose patulous pouch on the inferior portion. This tight capsular structure causes limited motion and shoulder pain when the arm is moved in any direction because the humeral head is nowpushed in the opposite directionof motion causing abutment of the humeral head superiorly into the acromion.
Normal Patulous Capsule Frozen Shoulder Capsule
There are three types of stiff or frozen shoulders.
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1. Idiopathic Frozen Shoulder occurs in females between the ages of 40-55 years of age. It occurs most often insidiously without an apparent reason or after a minor lifting event. Thecause is unknown but because it primarily affectsfemales in 70-90% of cases during a time when menopause is peaking, hormonal changes has been suggested as a potential cause.
2. Post-traumatic frozen shoulder occurs after an injury to the shoulder or after shoulder surgery when the shoulder is immobilized for a prolonged period of time causing the shoulder capsule to stiffen, as well as other shoulder interface layers including the subacromial spaces to adhere to each other. This type of frozen shoulder has more than the capsular layer involved and is more difficult to treat without surgical intervention that addresses all of the involved layers.
3. Glenohumeral Internal Rotation Deficit (GIRD) Shoulder- is a condition occurring in overhead athletes from repetitive overhead throwing activities which causes the anterior shoulder capsule to be loose, while the posterior and posterior inferior portion of the shoulder capsule to become tight subsequently forcing the shoulder to shift anteriorly and impinge on the internal fibers of the rotator cuff and posterior superior labrum when the arm is placed in the Late cocking position of a pitcher’s throw. Range of motion in the shoulder is limited in internal rotation, cross body adduction, andinternal rotation up the back.
Individuals with Diabetes, thyroid disorders, and heart disease are also more prone to developing a frozen shoulder and the likelihood that someone with a history of a frozen shoulder might have the opposite shoulder become a frozen shoulder in the future is about 50%. Once a frozen shoulder is treated, the likelihood of it returning on the same side is remote.
Treatment
The mainstay of treatment for a frozen shoulder isshoulder capsular stretching exercises. In most written literature related to frozen shoulders, the time to improve is said to be about 2 years. Our experience at ROC for idiopathic frozen shoulders is that about 90% of patients obtain 85% of their normal motion in about three months of a good supervised exercise program that is continued daily with a supplemental home exercise routine. 95% of patients presenting with idiopathic frozen shoulder are treated by non-operative means that include the use of a subacromial steroid injection, pain medication taken 30 minutes prior to therapy, heat used prior to stretching and anti-inflammatory medication.
Shoulder Six Pack Exercise Program
The therapy followed at ROC is very specific and focuses on an assisted passive stretching program that involves hands-on by a trained therapist. A patient cannot be left alone and expect improvement because the significant amount of pain experienced during capsular stretching will not invite the patient to do the exercises by themselves. This is why we advise patients to take the pain medication prescribed about 30 minutes prior to beginning therapy and also to warm up prior to stretching. The sequence of stretching is also extremely important and involves first stretching the shoulder capsule one plane at a time. Two such exercises include forward flexion stretching and cross body adduction stretching. This is exercise two, three and four in our six pack home program. Once these two planes of motion have been achieved, the anterior capsule and rotator interval is stretched by external rotation at the side and in abduction. The final stretch which is begun after the others planes of motion show moderate improvement is internal rotation stretching behind the back which is the last motion obtained. It is important that a therapist not focus on simple active assisted exercises with pulleys or strengthening exercises early on, since this does not address the problem and only delays improvement.
If therapy fails because the pain is intolerable, or the frozen shoulder has shown no improvement in spite of a good supervised therapy protocol over a 3-6 month period, we perform a combined closed manipulation and arthroscopic release of the shoulder capsule. This is because a closed manipulation alone, risks injury to the shoulder including a possible humeral fracture when the bone is weak. The frozen shoulder that is post traumatic is the most difficult to treat, and simple manipulation alone does not release all of the layers of adhesions that are present in the subacromial space and this is why an arthroscopic decompression must accompany the capsular release if success is to be achieved.