Anatomy of shoulder
- Static stabiliers
– Fibrous labrum (glenoid fossa is shallow, it is made deep by fibrous labrum. This creates a suction cup effect on humeral head
– Rotator cuff tendon insertions around the greater and lesser tuberosities
– Glenohumeral ligaments
- Muscles attachment
- Muscles to consider are
– Rotator cuff muscles
– Long head of biceps brachii (that attaches to supraglenoid tubercle and passes anterior to humeral head)
Anatomy in dislocation
Consider the above picture:
- Glenoid rim (located superolaterally in anterioinferior dislocation) is an obstacle
- To overcome the obstacle, traction must be provided anterolaterally.
- External rotation of the humeral head can also overcome the obstacle by providing more articular surface on the humeral head to receiving fossa.
- Or the glenoid rim can be repositioned by retroverting the scapula (bringing the scapula closer to spine)
- Muscle spasms continue to happen in dislocation.
- Abducting muscle (supraspinatus) will try to pull the humeral head up, fixing it in a subcoracoid position.
- Long head of biceps which passes in front of the humerus prevents the anterior movement of the humerus
- Subscapularis muscle will internally rotate he humerus, resisting any external rotation.
- As a result, anteroinferior should dislocation is presented with humerus in abduction and with internal rotation, like below:
- However, more often the arm is ADDUCTED.
– Due to pain, patient slouches to the side of injury, rotating the scapula forward
Patient slouches to the injured side, anteverting (rotating scapula forward) causing arm to appear adducted
There are tons of reduction methods described, but generally we can make a classification:
Note that even though a lot of textbooks mention traction for some of the methods listed under “without traction”, in original description the author did not use traction.
Arm in anatomical position: adducted against the torso
Kocher method: bend arms at elbow, press it agains the body, externally rotate until resistance, then lift the rotated upper arm as far as possible forward abd finally turn inwards slowly.
Cunningham method: Patient is asked to shrug the shoulder posteriorly (retroverting the scapula using the rhomboids), then while holding the patient’s wrist with elbow flexed, massage the shoulder muscles at mid-humeral level to reduce muscle spasm
Arm at zero position:
- Saha described zero position as “where the humero-scapular aligned axies coincide with the common axis of cone muscle groups (muscle around the shoulder)…Humerus is 165 degrees overhead and 45 degrees in front of coronal plane”. Sounds complicated, but essentially is like this:
- Zero position is the position when the cross stresses of all the muscles are eliminated, therefore allowing relocation of humeral head into the glenoid fossa.
- Patient lies in supine position. With the doctor in front, firmly support the top of the shoulder while the thumb of the same hand supports the dislocated humeral head.
- Using another hand, gently abducts the arm with the head of humerus supported (with the thumb just now, so that it does not migrate inferiorly).
- Once the arm is brought overhead, it is in zero position. Gently use the thumb to push the head of humerus into the glenoid fossa.
Modified Milch method
- The doctor stands behind the patient, using one hand to fix the spine of scapula (preventing it to move).
- The patient’s arm is abducted till overhead. External rotation is applied while abducting.
- An assistant can be asked to push the humeral head in once in zero position.
- While holding the patient’s wrist, apply traction to the affected limb in a neutral position beside the supine patient.
- Move the limb anteriorly and posteriorly in small oscillating movements while continuing to apply traction and start slowly abducting the limb.
- Once the limb is abducted to 90 degrees, externally rotate the limb at the shoulder, with ongoing traction and oscillating anterior/ posterior movements. Continue to slowly abduct the limb past this position.
- Reduction is usually achieved once the limb is abducted to 120 degrees.
Arm in forward flexion
- Stimson’s method: patient lies prone with the affected arm hanging downwards. A weight of 10 lb is applied to the wrist to disimpact the humeral head. Reduction is due to muscles fatigue.
- Spaso method: with the patient supine arm is gently lifted (the leg can be used to fix the patient’s position). Externally rotate the arm and push the head back to the glenoid fossa.
- With scapular manipulation: repositioning of the glenoid fossa.
– Traction is provided by forward flexion of the arm (with external rotation)
– Scapular manipulation is done by another doctor by pushing the inferior scapula tip medially and superior aspect of the scapula laterally (rotating the scapula bringing the glenoid fossa into correct alignment).
Arm in lateral flexion
- Hippocratic method: pulls the arm laterally to provide traction with a leg in axilla to provide countertraction
- Traction-counter traction method
Success rate ~ 60-100%. Some techniques are difficult for older patients, some are difficult for specific types of dislocation. So need to know more than one method.
In my opinion, reduction with no traction is better than with traction because traction may injure the brachial plexus.
- A few principles to remember
– External rotation helps in reduction
– Retroverting the scapula helps in reduction
– Abducting the arm overhead eliminates all the muscular forces –> helps in reduction
- My first choices would be
– If supine patient: Milch (or modified Milch or FARES, know one at least!) or Kocher
– If seated patient: Cunningham or Kocher or Milch
- If the first choices dont work
– Scapular manipulation technique can be used
– Stimson can be considered but it takes time.
After reduction, immobilize with humerus in internal rotation.
- There is a study suggesting external or internal does not matter but the study was underpowered.
- Immobilization in external rotation is (in my opinion) quite awkward.
- Neil J Cunningham. Techniques for reduction of anteroinferior shoulder dislocation. Emergency Medicine Australasia, 2005;17:463–71