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eReport 2005-08

Photo of Steve Wong

Steve Wong,  BHK, BSc PT, MCPA
Physiotherapist

Day-to-day activities and most sports require our upper bodies to move against little external resistance. Whether it's throwing, making a tackle on the field or performing a golf swing, we need adequate mobility in our shoulders.

The shoulder, or glenohumeral joint, is one of the most mobile joints in our body. However, it sacrifices STABILITY for this needed MOBILITY. This edition of eReport discusses the concept of shoulder dislocation and subluxation - factors that contribute to shoulder stability and the rehabilitation for shoulder instability or dislocations.

 

What is the difference between dislocation and subluxation?

Dislocation can be defined by when a joint is forced out of its anatomical or resting position, and remains dislodged.

Subluxation can be defined by when a joint momentarily slides out of its anatomical resting position but quickly moves back into a normal resting position. Subluxation may occur after a previous dislocation or may progress to a dislocation.


How do I know if I subluxed my shoulder joint?

  • Have you been involved in a falling incident while having your arm fully outstretched behind you?
  • Do you feel your shoulder moving 'in' and 'out' of the joint when walking or performing light activities?
  • Does your arm feel 'life-less' or weak when you try to lift it up above your shoulders?
  • Do you have sharp pain in your shoulder when throwing or reaching out sideways?
  • Is there any 'catching', 'clunking' or locking during arm movements?

Shoulder instabilities can be grouped into the following categories:

  1. Anterior (front of the joint) -> most common

  2. Posterior (back of the joint)

  3. Multi-directional (more than one area of the joint)

What protects my shoulder from dislocation?:

  1. Shape and design of the shoulder socket - the socket or glenoid fossa is normally angled upwards to provide a 'supporting ledge' for the arm bone.

  2. The LABRUM or cartilage ring deepens the surface area of contact so that the arm bone has more supportive surface to sit on.

  3. LIGAMENTS surround the entire joint from top to bottom and front and back. These 'elastic bands' are extremely strong and help to prevent any excessive movement between the arm bone and the socket.

  4. The CAPSULE or fibrous lining surrounding the joint becomes continuous with the ligaments and muscles helping to reinforce all aspects of the glenohumeral joint.

  5. A thin layer of fluid exists between the arm bone and the socket which creates a 'vacuuming effect'. This suctioning phenomena helps to create a constant pull between the two bones.

  6. The Rotator Cuff muscle group helps to keep the arm bone centered into the socket while producing a 'downward pull' of the arm bone into the joint. This maximizes joint compression.

Shoulder dislocations can damage any of the above components leading to pain and muscle inhibition (decreased activity), resulting in chronic instability.


What kind of rehabilitation program is appropriate
for an unstable shoulder?

  1. Regaining strength and control of the shoulder blade (scapula) stabilizers in order to achieve an optimal resting position of the scapula (Upper Fibers of Trapezius; Lower fibers of Trapezius; Serratus Anterior).
  2. Restoring functional strength of the rotator cuff (Supraspinatus; Infraspinatus; Teres Minor; Subscapularis).
  3. Postural exercises to maintain proper positioning of the scapula.

If conservative treatment fails, surgical intervention is sometimes required for traumatic shoulder instabilities.

Steve Wong,  BHK, BSc PT, MCPA.
Physiotherapist

Printed: August 2005
Copyright ©2005 SEMI

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I want to take this opportunity to acknowledge and thank you and your staff for their dedication and professionalism. Six months ago I started experiencing chronic pain in my left knee and calf. After numerous tests my family doctor was not sure as to what was causing this ongoing problem. Through a friend, I was referred to you. The sports medicine Doctor diagnosed my problem as a torn meniscus with some degeneration of the cartlilage in my knee. The MRI that the Doctor arranged, in turn supported this. He suggested that physiotherapy would help before we entertained anything more invasive. My physiotherapist worked with me for several months and today I am pain free. Once again I say "Thank You". I believe my progress and its success is due entirely to the staff at Toronto SEMI.

Judy Maus..