Multidirectional Instability of the Shoulder (MDI)

Shoulder instability is a common injury among people participating in contact and noncontact athletic activities. While many people associate shoulder instability with a traumatic event such as a dislocation, multidirectional instability (MDI) can occur without trauma. MDI commonly occurs in people who have increased a joint’s movement, or have not exercised the joint over a period of time. Weakness of the shoulder joint (rotator cuff) can increase the risk of MDI. After treating the pain and inflammation caused by MDI of the shoulder, physical therapy focuses on strengthening the muscles that support the shoulder blade (scapula) and shoulder joint (rotator cuff) to aid a return to activity and prevent reinjury.

What is Multidirectional Instability of the Shoulder?

MDI of the shoulder is defined as generalized laxity (looseness) of the joint due to increased mobility and joint weakness. The shoulder joint may “slip” in and out of its socket in a forward (anterior), backward (posterior), or downward (inferior) direction. 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. The most common cause of MDI is overuse of the shoulder.

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How Does it Feel?

Symptoms of MDI of the shoulder may vary in terms of location and intensity. Although sometimes the shoulder can be dislocated, often people report their shoulder will “slip” out and go right back into the socket. They may also 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. Pain 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. Since the symptoms of MDI vary widely, a health care professional will likely take a detailed history and perform a thorough physical exam to make an accurate diagnosis.

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Signs and Symptoms

Signs and symptoms of MDI of the shoulder vary from person to person, but may include:

  • Pain with pushing, pulling, or carrying heavy objects
  • Pain when performing an overhead activity
  • Pain during or after exercise
  • A feeling that the shoulder is “shifting” (including in bed at night)
  • 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

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How Is It Diagnosed?

The physical therapist can 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 physical therapist will take a detailed patient history. The 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.

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 tear.

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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, show you how to apply ice and heat to modulate the pain, and recommend the use of a sling for pain control.

The therapist will design an exercise program to improve your shoulder’s strength and stability. 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.

Once your strength and range of motion have returned to a normal level, your physical therapist will help you gradually return to your sport activity. Throwing, playing, or swimming will typically begin in an interval format, allowing a progressive return to activity.

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Can this Injury or Condition be Prevented?

Preventing MDI of the shoulder falls into 3 categories:

  • Strengthening and stretching the scapular muscles and the muscles of the rotator cuff. Athletes may perform scapular and rotator cuff strengthening exercises 3-4 times per week.
  • Monitoring the volume of activity performed. This practice is just as important as strengthening exercises. Baseball players will often use pitch counts to avoid overuse injuries, while 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.

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Real Life Experiences

Sarah is a competitive swimmer training to compete at the university level. For the past few weeks, however, Sarah 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 assesses her shoulder and notes pain along the front of the joint. Sarah says her arm feels weak when she tries to reach behind her, and she can’t hold her shoulder blade in place when the arm is pushed. Her physical therapist diagnoses MDI of the shoulder.

He places Sarah on a strengthening and stabilization program for the shoulder and upper back, and advises her to take a break from swimming for 4 weeks. During this time, Sarah maintains her new strengthening program, which includes scapular and rotator cuff strengthening with therabands and lightweight dumbbells, stabilization activity with gym balls and a BodyBlade, and core strengthening exercises. At the end of 4 weeks her anterior shoulder pain has gone away, and her shoulder strength and mobility have improved.

Sarah begins swimming in the pool at an easy pace every other day and gradually progresses back toward her original volume of swimming activity. Over the course of the next month, she returns to her previous competitive level. Come fall, Sarah is able to compete 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.

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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 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.

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Further Reading

The following articles provide some of the best scientific evidence related to physical therapy treatment of phantom limb pain. 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.

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.

Acknowledgements: Andrew Naylor, PT, DPT, SCS

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