Question: We have 14 siblings in our family , at least 10 of us has had a frozen shoulder.  We are wondering why?  should we be concerned?

Reference:
 Frozen shoulder Overview Frozen shoulder, also known as adhesive capsulitis, is a condition characterized by stiffness and pain in your shoulder joint. Signs and symptoms typically begin gradually, worsen over time and then resolve, usually within one to three years. Your risk of developing frozen shoulder increases if you're recovering from a medical condition or procedure that prevents you from moving your arm - such as a stroke or a mastectomy. Treatment for frozen shoulder involves range-of-motion exercises and, sometimes, corticosteroids and numbing medications injected into the joint capsule. In a small percentage of cases, arthroscopic surgery may be indicated to loosen the joint capsule so that it can move more freely. It's unusual for frozen shoulder to recur in the same shoulder, but some people can develop it in the opposite shoulder. Symptoms Frozen shoulder typically develops slowly, and in three stages. Each stage can last a number of months. - Freezing stage. Any movement of your shoulder causes pain, and your shoulder's range of motion starts to become limited. - Frozen stage. Pain may begin to diminish during this stage. However, your shoulder becomes stiffer, and using it becomes more difficult. - Thawing stage. The range of motion in your shoulder begins to improve. For some people, the pain worsens at night, sometimes disrupting sleep. Causes The bones, ligaments and tendons that make up your shoulder joint are encased in a capsule of connective tissue. Frozen shoulder occurs when this capsule thickens and tightens around the shoulder joint, restricting its movement. Doctors aren't sure why this happens to some people, although it's more likely to occur in people who have diabetes or those who recently had to immobilize their shoulder for a long period, such as after surgery or an arm fracture. Risk factors Certain factors may increase your risk of developing frozen shoulder. Age and sex People 40 and older, particularly women, are more likely to have frozen shoulder. Immobility or reduced mobility People who've had prolonged immobility or reduced mobility of the shoulder are at higher risk of developing frozen shoulder. Immobility may be the result of many factors, including: - Rotator cuff injury - Broken arm - Stroke - Recovery from surgery Systemic diseases People who have certain diseases appear more likely to develop frozen shoulder. Diseases that might increase risk include: - Diabetes - Overactive thyroid (hyperthyroidism) - Underactive thyroid (hypothyroidism) - Cardiovascular disease - Tuberculosis - Parkinson's disease Diagnosis During the physical exam, your doctor may ask you to move in certain ways to check for pain and evaluate your range of motion (active range of motion). Your doctor might then ask you to relax your muscles while he or she moves your arm (passive range of motion). Frozen shoulder affects both active and passive range of motion. In some cases, your doctor might inject your shoulder with a numbing medicine (anesthetic) to determine your passive and active range of motion. Frozen shoulder can usually be diagnosed from signs and symptoms alone. But your doctor may suggest imaging tests - such as X-rays or an MRI - to rule out other problems. Treatment Most frozen shoulder treatment involves controlling shoulder pain and preserving as much range of motion in the shoulder as possible. Medications Over-the-counter pain relievers, such as aspirin and ibuprofen (Advil, Motrin IB, others), can help reduce pain and inflammation associated with frozen shoulder. In some cases, your doctor may prescribe stronger pain-relieving and anti-inflammatory drugs. Therapy A physical therapist can teach you range-of-motion exercises to help recover as much mobility in your shoulder as possible. Your commitment to doing these exercises is important to optimize recovery of your mobility. Surgical and other procedures Most frozen shoulders get better on their own within 12 to 18 months. For persistent symptoms, your doctor may suggest: - Steroid injections. Injecting corticosteroids into your shoulder joint may help decrease pain and improve shoulder mobility, especially in the early stages of the process. - Joint distension. Injecting sterile water into the joint capsule can help stretch the tissue and make it easier to move the joint. - Shoulder manipulation. In this procedure, you receive a general anesthetic, so you'll be unconscious and feel no pain. Then the doctor moves your shoulder joint in different directions, to help loosen the tightened tissue. - Surgery. Surgery for frozen shoulder is rare, but if nothing else has helped, your doctor may recommend surgery to remove scar tissue and adhesions from inside your shoulder joint. Doctors usually perform this surgery with lighted, tubular instruments inserted through small incisions around your joint (arthroscopically). Lifestyle and home remedies Continue to use the involved shoulder and extremity as much as possible given your pain and range-of-motion limits. Applying heat or cold to your shoulder can help relieve pain. Alternative medicine Acupuncture Acupuncture involves inserting extremely fine needles in your skin at specific points on your body. Typically, the needles remain in place for 15 to 40 minutes. During that time they may be moved or manipulated. Because the needles are hair thin and flexible and are generally inserted superficially, most acupuncture treatments are relatively painless. Transcutaneous electrical nerve stimulation (TENS) A TENS unit delivers a tiny electrical current to key points on a nerve pathway. The current, delivered through electrodes taped to your skin, isn't painful or harmful. It's not known exactly how TENS works, but it's thought that it might stimulate the release of pain-inhibiting molecules (endorphins) or block pain fibers that carry pain impulses. 

Answer: The bones, ligaments and tendons that make up your shoulder joint are encased in a capsule of connective tissue. Frozen shoulder occurs when this capsule thickens and tightens around the shoulder joint, restricting its movement. Doctors aren't sure why this happens to some people, although it's more likely to occur in people who have diabetes or those who recently had to immobilize their shoulder for a long period, such as after surgery or an arm fracture.