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 Adhesive capsulitis Shoulder pain - frozen Summary Frozen shoulder is a condition in which the shoulder is painful and loses motion because of inflammation. Causes The capsule of the shoulder joint has ligaments that hold the shoulder bones to each other. When the capsule becomes inflamed, the shoulder bones are unable to move freely in the joint. Most of the time, there is no cause for frozen shoulder. Risk factors include: Diabetes Thyroid problems Changes in your hormones, such as during menopause Shoulder injury Shoulder surgery Open heart surgery Cervical disk disease of the neck Women 40 to 70 years old are most affected Symptoms Main symptoms of a frozen shoulder are: Decreased motion of the shoulder Pain Stiffness Frozen shoulder without any known cause starts with pain. This pain prevents you from moving your arm. This lack of movement can lead to stiffness and even less motion. Over time, you are not able to do movements such as reaching over your head or behind you. Exams and Tests Your health care provider will ask about your symptoms and examine your shoulder. A diagnosis is often made when you are not able to rotate your shoulder. You may have x-rays of the shoulder. This is to make sure there is no other problem, such as arthritis or calcium deposits. Sometimes, an MRI exam shows inflammation, but these types of imaging tests are not needed to diagnose frozen shoulder. Treatment Pain is treated with NSAIDs and steroid injections. Steroid injections and physical therapy can improve your motion. It can take a few weeks to see progress. It may take as long as 6 to 9 months for complete recovery. Physical therapy is intense and needs to be done every day. Left untreated, the condition often gets better by itself within 2 years with little loss of motion. Risk factors for frozen shoulder, such as diabetes or thyroid problems, should also be treated. Surgery is recommended if nonsurgical treatment is not effective. This procedure (shoulder arthroscopy) is done under anesthesia. During surgery the scar tissue is released (cut) by bringing the shoulder through a full range of motion. Arthroscopic surgery can also be used to cut the tight ligaments and remove the scar tissue from the shoulder. After surgery, you may receive pain blocks (shots) so you can do physical therapy. Follow instructions on caring for your shoulder at home. Outlook (Prognosis) Treatment with physical therapy and NSAIDs often restores motion and function of the shoulder within a year. Even untreated, the shoulder may get better by itself in 2 years. After surgery restores motion, you must continue physical therapy for several weeks or months. This is to prevent the frozen shoulder from returning. If you do not keep up with physical therapy, the frozen shoulder may come back. Possible Complications Complications may include: Stiffness and pain continue even with therapy The arm can break if the shoulder is moved forcefully during surgery When to Contact a Medical Professional If you have shoulder pain and stiffness and think you have a frozen shoulder, contact your provider for referral and treatment. Prevention Early treatment may help prevent stiffness. Call your provider if you develop shoulder pain that limits your range of motion for an extended period. People who have diabetes or thyroid problems will be less likely to get frozen shoulder if they keep their condition under control. Review Date 11/27/2016 Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 

Answer: It is not known what causes frozen shoulder. Risk factors include: diabetes, thyroid problems, hormonal changes, e.g., during menopause, shoulder disease, injury or surgery, or other types of surgery. If you don't treat the risk factors and don't use the full range of motion, the frozen shoulder may return.