Shoulder Subluxation

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Definition

Shoulder subluxation is a joint problem which mostly affects athletes competing in sports like swimming, baseball , handball and tennis. It’s a minor form of shoulder luxation, but is also very painful for the patient. They describe a loss of power in the affected arm and a feeling of numbness.(2)

Clinically relevant anatomy

The shoulder joint consists of 3 bone structures, which are: humerus, scapula and clavicula. These bones make a total of 3 synovial joints: gleno-humeral , sterno-clavicular and acromio-clavicular joint. Besides these you also find the subacromial “joint” and the scapular-thoracal “joint”. The shoulder exists as well of muscles and ligaments. The most important muscles are m. Deltoideus, m. Supra and Infrspinatus, m. Teres minor and major and m. Pectoralis. The biggest and most important ligament is the Lig. Glenohumerale, who is in most cases the one that is most affected. In cases of shoulder subluxation, the mainly affected joint is the gleno-humeral joint. The most common cause of shoulder subluxation is found in the wrong orientation or absence of the lig. gleno-humerale. (1)

Picture 1, shoulder joints 

Epidemiology

Previous studies showed that there was no relationship between shoulder pain, shouldersubluxation and gender. It equally occurs within man and women. (1)
Shoulder subluxations occur a lot in people with emiplegic stroke’s. The reported incidence varies greatly, from 17% to 81% depending the study. (2, 3)

Characteristics/clinical presentation

The main problem with shoulder subluxation is the instability of the gleno-humeral joint. The anatomy of this joint makes sure that we have a lot of mobility, but it sacrifices stability. Research by Basmajian determined that the musculus supraspinatus and in minor ways also the posterior fibers of the deltoid muscle play a key role in maintaining glenohumeralalignment. Chaco and Wolf, did confirm this in their study, which said that the supra spinatus is very important in preventing the downward subluxation of the humerus. Subluxation occurs with the shoulder in abduction and externally rotated. (4) Other research shows that the most important ligamental structure to maintain correct shoulder position and also to prevent shoulder subluxation is the inferior glenohumeral ligament. (5) This ligament is most important during external rotation and abduction during the cocking face of the throwing motion.
Shoulder subluxation can lead to soft tissue damage as traction damage can occur due to gravitational pull forces and poor protection is offered by a weak shoulder. (2)

Diagnostic Procedures

Symptoms:
Shoulder subluxations come with:

• Pain in the shoulder region
• Loss off function in the shoulder region. (2)

Functional testing:
The subluxationtest is positive = resistance is given, when patient brings arm in throwing stance, in internal rotation direction.
Pain in the ventral capsule indicates a frontal capsule lesion.
Pressure during resistance test on the dorsal part of the humerus can provoke ventral gliding. The result is sudden pain in the shoulder and in a number of cases there is a subluxation to the front. This test can be conducted in different degrees of abduction and with or without the support of the upper arm.(3)

Physical Therapy Management

-Therapy:
The traditional therapy for shoulder subluxations primarily consists of reducing the chance to re-subluxate the shoulder, by wearing a sling. The disadvantage of these slings are that they place the arm in a poor position which likely to cause damage to the soft tissue in the form of contractures. They also have negative effects on symmetry, balance and body image. (4)

-Electrical Stimulation:
There has been a randomized controlled study on the prevention of shoulder subluxation with electrical stimulation. Electrodes were positioned on the fossa supraspinale and the posterior aspect of the upper arm. The goal of this positioning was to stimulate the musculus supraspinatus and the posterior deltoid muscles. The results have shown that the treatment group had significantly less subluxations and pain after the treatment period, but at the end of the follow-up period the differences between the 2 groups were not significant. (4)

-Prevention:
Strengthening exercises to re-establish the strength of the rotator cuff muscles is recommended. Another good way to prevent a shoulder subluxation is to encourage functional activities that are task-specific to increase voluntary motor control around the shoulder. (7)
Initial physical therapy interventions may include:

• Mobility exercises including PROM, AAROM, AROM
• Motor control training
• Scapular stabilization
• Isometric and low-grade strengthening exercises
• Manual therapy directed at the Gleno-humeral, Acromio-Clavicular and Sterno-

   Clavicular joint

• Manual therapy of cervicothoracic spine and upper ribs
• Activity modification

Late stages of rehabilitation of rotator cuff injury include progressive resistive strengthening, proprioception and sport-specific exercises.

References

-Articles:
(1): Aras MD et al., Shoulderpain in hemiplegia, results from a national rehabilitation hospital in Turkey, 2004

(2) : Shis-Wei Huang et al., Relationship between severity of shoulder subluxation and soft-tissue injury in hemiplegic stroke patients, 2011
Level of evidence: 2B

(3): Hartwig M et al., Functional orthosis in shoulder joint subluxation after ischaemic brain stroke to avoid post-hemiplegic shoulder-hand syndrome: a randomized clinical trial, 2012
level of evidence: 1B
(4): Sandra L. Linn, MPhil; Malcolm H. Granat, PhD; Kennedy R. Lees, MB, ChB,Prevention of Shoulder Subluxation After Stroke With Electrical Stimulation, 1999
Level of evidence: 1B
(5): Daniel F Massimini, Patrick J Boyer, Ramprasad Papannagari, Thomas J Gill, Jon P Warner, and Guoan Li. J Orthop Surg Res. In-vivo glenohumeral translation and ligament elongation during abduction and abduction with internal and external rotation, 2012

Level of evidence: 2C

(6): K. Hamada, H. Fukuda, T. Nakajima, N. Yamada, The inferior capsular shift operation for instability of the shoulder. Tokai University School of Medicine, Isehara, Japan, 1999

Level of evidence: 1B

(7): Kumar, Praveen1; Kassam, Jamila2; Denton, Carys2; Taylor, Emma2; Chatterley, Angela2, Risk factors for inferior shoulder subluxation in patients with stroke, Physical Therapy Reviews, Volume 15, Number 1, February 2010 , pp. 3-11(9), Publisher: Maney Publishing
Level of evidence: 1A

- Books:

Gray’s Anatomy, Anatomical Basics of Clinical Practice, thirty-ninth edition, Henry Gray.

-Visual support:
http://www.youtube.com/watch?v=Z27B3a1lMdU
http://www.youtube.com/watch?v=UeMPc9wcD0I