Physical Therapist's Guide to Multidirectional Instability of the Shoulder (MDI)
Shoulder instability is a common injury among people participating in contact and non-contact athletic activities. Although shoulder instability can result from a traumatic event such as a dislocation, multidirectional instability (MDI) can occur without trauma. MDI commonly occurs in people who have increased shoulder joint looseness (laxity) with small, usually unnoticed injuries caused by repetitive overuse. Weakness of the shoulder joint (rotator cuff) and shoulder blade (scapula) muscles can increase the risk of MDI. After treating the pain and inflammation caused by MDI of the shoulder, physical therapy focuses on strengthening the shoulder muscles to aid a return to activity and to prevent reinjury.
What is Multidirectional Instability of the Shoulder?
Multidirectional instability (MDI) of the shoulder is defined as generalized looseness (laxity) of the shoulder joint due to increased mobility and joint weakness. Many factors, including congential looseness, muscular imbalances, shoulder blade position, shoulder structure variations, and certain repetitive activities, can contribute to the development of MDI. When the shoulder becomes loose, the joint may "slip" in and out of its socket in more than 1 direction—forward (anterior), backward (posterior), or downward (inferior). This laxity may be exaggerated in people who participate in activities that require repeated overhead movement of the arm, such as baseball pitchers or swimmers. Overuse of the shoulder is often associated with and contributes to MDI. MDI is less common in people aged 40 years and older due to the natural stiffening of the tissues around the shoulder with age.
How Does it Feel?
Symptoms of MDI of the shoulder may vary in terms of their location and intensity. Although sometimes the shoulder can be dislocated, often people report their shoulder will "slip" out of its socket and go right back into it. They also may report instances where they feel like their shoulder is about to slip in and out of its socket, but they modify their activity to prevent it from happening. Some individuals will even avoid certain movements due to their fear that the shoulder will “pop out.”
Pain caused by MDI may be felt in a number of areas around the shoulder—in the front of the shoulder when pitching a baseball, or throughout the entire shoulder after a repetitive activity like swimming. Symptoms of MDI vary widely; your health care professional will likely take a detailed health history and perform a thorough physical examination to make an accurate diagnosis.
Signs and Symptoms
Signs and symptoms of MDI of the shoulder vary from person to person, but may include:
- Pain and/or instability with pushing, pulling, or carrying heavy objects
- Pain and/or instability when performing an overhead activity
- Pain and/or instability during or after exercise
- A feeling that the shoulder is "shifting" (including in bed at night)
- The sensation of the shoulder slipping out of its socket and back into it
- Fear of putting the shoulder in certain positions
- Numbness and tingling sensations in the affected arm
- Clicking and popping sensations with movement
- Weakness when performing athletic movements, especially overhead and away from the body
- Loss of performance ability in sport activities
- Fatigue with repetitive activity
How Is It Diagnosed?
Your physical therapist will take a detailed health history, and assess the mobility of the shoulder joint in a variety of positions as well as the strength of the rotator cuff and scapular muscles. Your therapist also may assess your core strength, the presence of any nerve involvement, your joint-body awareness, and your overall muscle control. Your physical therapist may gently pull downward on the shoulder to look for increased movement in the joint, or push forward or backward on the arm bone within the shoulder joint to assess increased areas of mobility. Your therapist will use a cluster of shoulder instability tests to help diagnose MDI.
For a more detailed diagnosis, a physician may order x-rays to rule out bone fractures, and can order an MRI (magnetic resonance imaging) to diagnose injury within the shoulder complex, such as a muscle, capsule, or labral tear.
How Can a Physical Therapist Help?
Your physical therapist will evaluate your shoulder injury and find areas of weakness and muscular imbalance. The first step to treating the injury is managing pain and inflammation. Your physical therapist may advise you to stop or modify any activities that aggravate the injury and show you techniques to lessen pain, omitting the need for strong medications, such as opioids.
Your physical therapist will design an exercise program to improve your shoulder's strength and stability and address other factors that contribute to your lack of stability, such as your core strength and body awareness. Initially, you'll perform gentle exercises close to the body to limit your discomfort. After strength and stability have improved, your physical therapist will introduce more dynamic exercises specific to your activity goals. The dynamic exercises are created specifically to improve your body’s ability to handle the stress and demands of your activities, work, and/or sport.
Physical therapists help athletes with MDI gradually return to sport once their strength and range of motion have returned to normal levels. Throwing, playing, or swimming will typically begin in an interval format, allowing a progressive return to activity.
Can this Injury or Condition be Prevented?
Although MDI cannot be totally prevented, physical therapy can lessen the effects of shoulder laxity. Controlling MDI of the shoulder falls into 3 categories:
- Strengthening the scapular muscles and the muscles of the rotator cuff by improving shoulder mechanics, muscular imbalances, body awareness, and muscle control. Athletes may perform scapular and rotator cuff strengthening exercises 3 to 4 times per week.
- Monitoring the volume of activity performed. This practice is just as important as strengthening exercises. Baseball players, for example, will often use pitch counts to avoid overuse injuries; swimmers attempt to maintain weekly yardage totals.
- Maintaining proper form and technique. Good coaching on proper form and technique by a qualified coaching professional can be a valuable asset in preventing injuries in the young athlete population.
Real Life Experiences
Sarah is a 19-year-old full-time student and competitive swimmer training to compete at the university level. For the past few weeks, however, she has been experiencing pain in the front of her shoulder when swimming. She has tried to rest her shoulder and has decreased how far she swims daily in the pool, but her pain is persistent. She contacts her physical therapist.
Sarah's physical therapist takes her health history, and asks her to describe her symptoms. Sarah says her arm feels weak when she tries to reach behind her, and she feels like her shoulder might “pop out” at the extremes of her swimming motions. Her physical therapist assesses her shoulder and notes that she feels pain along the front of the joint. He notes increased shoulder joint motion when he gently pushes on the shoulder in multiple directions. He diagnoses MDI of the shoulder.
Sarah’s physical therapist advises her to take a break from swimming for 4 weeks. He designs an individualized strengthening and stabilization program for the shoulder and upper back based on her condition and goals.
Sarah maintains her new strengthening program, which includes scapular and rotator-cuff strengthening with therabands and lightweight dumbbells, stabilization activities with gym balls and other equipment, and core strengthening exercises.
At the end of 4 weeks of treatment, Sarah’s shoulder pain has gone away, and her shoulder strength and stability have improved. Her physical therapist adds progressive exercises focused on her swimming mechanics; he uses multiple tests and measures to assess her ability to return to swimming at full strength.
The following week, Sarah’s physical therapist approves her return to swimming, advising her to swim at an easy pace every other day. With his guidance, she gradually progresses back toward her original volume of swimming activity.
Over the course of the next month, Sarah returns to her previous competitive level. She notices her improved strength and lap times, and gladly continues with the strengthening and stabilization exercises that her physical therapist has taught her.
Come fall, Sarah is able to compete at full strength with her team—and helps them win a regional competition!
This story was based on a real-life case. Your case may be different. Your physical therapist will tailor a treatment program to your specific case.
What Kind of Physical Therapist Do I Need?
All physical therapists are prepared through education and experience to treat multidirectional instability. However, you may want to consider:
- A physical therapist who is experienced in treating people with multidirectional instability. Some physical therapists have a practice with a sports or orthopedic focus.
- A physical therapist who is a board-certified clinical specialist or who completed a residency or fellowship in sports or orthopedic physical therapy. This physical therapist has advanced knowledge, experience, and skills that may apply to your condition.
You can find physical therapists who have these and other credentials by using Find a PT, the online tool built by the American Physical Therapy Association to help you search for physical therapists with specific clinical expertise in your geographic area.
General tips when you're looking for a physical therapist (or any other health care provider):
- Get recommendations from family and friends or from other health care providers.
- When you contact a physical therapy clinic for an appointment, ask about the physical therapists' experience in helping people who have multidirectional instability.
- During your first visit with the physical therapist, be prepared to describe your symptoms in as much detail as possible, and say what makes your symptoms worse.
The American Physical Therapy Association (APTA) believes that consumers should have access to information that could help them make health care decisions and also prepare them for a visit with their health care provider.
The following articles provide some of the best scientific evidence related to physical therapy treatment of multidirectional instability. The articles report recent research and give an overview of the standards of practice both in the United States and internationally. The article titles are linked either to a PubMed* abstract of the article or to free full text, so that you can read it or print out a copy to bring with you to your health care provider.
Cools AM, Borms D, Castelein B, et al. Evidence-based rehabilitation of athletes with glenohumeral instability. Knee Surg Sports Traumatol Arthroscopy. 2016;24:382–389. Article Summary in PubMed.
Longo UG, Rizzello G, Loppini M, et al. Multidirectional instability of the shoulder: a systematic review. Arthroscopy. 2015:31(12);2431–2443. Article Summary in PubMed.
Merolla G, Cerciello S, Chillemi C, et al. Multidirectional instability of the shoulder: biomechanics, clinical presentation, and treatment strategies. Eur J Orthop Surg Traumatol. 2015;25:975–985. Article Summary in PubMed.
Warby SA, Pizzari T, Ford JJ, et al. The effect of exercise-based management for multidirectional instability of the glenohumeral joint: a systematic review. J Shoulder Elbow Surg. 2014;23;128–142. Article Summary in PubMed.
Lee JH, Kim NR, Moon SG, et al. Multidirectional instability of the shoulder: rotator interval dimension and capsular laxity evaluation using MR arthrography. Skeletal Radiol. 2013;42:231–238. Article Summary in PubMed.
Heinlein SA, Cosgarea AJ. Biomechanical considerations in the competitive swimmer’s shoulder. Sports Health. 2010;2(6):519–525. Free Article.
Goldin J, Sekiya JK. Systematic review of rehabilitation versus operative stabilization for the treatment of first-time anterior shoulder dislocations. Sports Health. 2010;2(2):156–162. Free Article.
Kim SH. Multidirectional instability of the shoulder: current concept. Sports Med Arthrosc Rehabil Ther Technol. 2009;1(1):12. Free Article.
Lo IK, Nonweiler B, Woolfrey M, et al. An evaluation of the apprehension, relocation, and surprise tests for anterior shoulder instability. Am J Sports Med. 2004;32(2):301–307. Article Summary on PubMed.
Cordasco FA. Understanding multidirectional instability of the shoulder. J Athl Train. 2000;35(3):278–285. Free Article.
Mahaffey BL, Smith PA. Shoulder instability in young athletes. Am Fam Physician. 1999;59(10):2773–2782. Free Article.
* PubMed is a free online resource developed by the National Center for Biotechnology Information (NCBI). PubMed contains millions of citations to biomedical literature, including citations in the National Library of Medicine’s MEDLINE database.
Revised by Chris Gerona, PT, DPT. Authored by Andrew Naylor, PT, DPT, a board-certified clinical specialist in sports physical therapy. Reviewed by the MoveForwardPT.com editorial board.
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