Frozen shoulder is the classical stiffness and pain in the shoulder girdle that greatly restricts motion and movement across this ball and socket joint. Seen in 2% of general population and with a slightly higher incidence in women, frozen shoulder or Adhesive Capsulitis is more common in middle aged populations with peak occurrence in individuals between 40 to 60 years of age.
What is frozen shoulder?
The shoulder joint is a classic ball and socket joint that enables 3-dimensional movement of upper limb. The movement of upper limb is supported by ligaments that hold the articulating surfaces of the bones to ensure free movement; however, when the shoulder joint becomes inflamed, pain and stiffness results making movement across the shoulder joint difficult.
Sign and symptoms of Frozen Shoulder:
Frozen shoulder is classically the result of capsulitis or inflammation of joint capsule.
Following symptoms are characteristic:
– Pain in the shoulder that varies in severity and character, from dull and aching to sharp and stabbing that prevents individuals normal shoulder activity
– Restricted range of motion or shoulder movement
A classic frozen shoulder starts with the pain that limits the movement across the shoulder joint. Decreased activity leads to stiffness of ligaments and tissues supporting the shoulder joint, further limiting the movement and range of motion.
How does Frozen Shoulder develop?
In majority of the cases, no specific cause can be ascertained to frozen shoulder; however, the following risk factors greatly increase the risk:
– Previous history of shoulder surgery or shoulder injury that involves a ligament or joint capsule can lead to adhesive capsulitis due to prolonged inactivity or immobility across the shoulder joint.
– Cervical disc herniation is also a recognized risk factor that manifests itself as frozen shoulder in early cases.
– Long standing, uncontrolled Diabetes Mellitus is another established risk factor that impairs the inflammatory response in the shoulder region after a trivial injury. About 10 to 20% of all diabetics develop Adhesive capsulitis at some point of their life.
– Hyperthyroidism as it is known to affect ligaments and muscle spindles. Same is true with hypothyroidism.
– Open heart surgery and neurological diseases like Parkinson’s disease are also known factors
Any of the above risk factors increase the risk of irritation or injury to shoulder capsule. Since the shoulder capsule has an extremely rich nerve supply, pain is out of proportion to the degree of tissue damage that limits the mobility of shoulder joint. Prolonged immobility and hypo-activity leads to stiffness and thickening of shoulder capsule that further aggravates pain if any movement is attempted.
The patho-physiology of frozen shoulder can be divided into 3 stages:
– Freezing that involves limitation of shoulder activity due to the gradual increase and severity of pain. This stage can last from up to 6 weeks to about 9 months depending on the management
– Frozen stage that lasts for about 3 to 6 months; mild improvement in pain symptoms but stiffness may interfere with the mobility and full range of motion.
– Thawing stage in which the range of motion gradually improves with an absolute return by almost 6 months to as long as 2 years.