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Table of Contents
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Overview of Shoulder Instability
Overview
The shoulder is a very mobile joint and is therefore inherently prone to instability. According to Doukas and Speer, “clinical instability manifests itself at end-range of motion, and reflects increased glenohumeral translation involving a spectrum from microinstability to frank dislocation.”[1] The structures that enable shoulder functional stability, defined as the maintenance of the humeral head in the glenoid fossa, are both static and dynamic components, working in concert.[1] Annually, 30-40% of adults experience shoulder discomfort, leading to 1-5% of the population to seek medical help for the condition.[2]
Types of Instability[3]
- Subluxation – separation of the articular surfaces with spontaneous reduction.
- Dislocation – complete separation of articular surfaces and requires a specific movement or manual reduction to relocate the joint.
Grades of Glenohumeral translation[4]
| Grades of GH translation | Description |
|---|---|
| Grade I | Up to 50% humeral head translation, with the head riding up to the glenoid rim but spontaneously reducing. |
| Grade II | The humeral head has more than 50% translation; the head feels as through it is riding over the glenoid rim but spontaneously reduces. (Note: normal hypermobile shoulders may show grade II translation in any direction. |
| Grade III | The humeral head rides over the glenoid rim and does not spontaneously reduce. |
Anatomy
The shoulder joint involves the articulation of the humerus, scapula and clavicle. The humeral head sits in a ‘golf ball on tee’ arrangement in the glenoid fossa of the scapula. The scapula articulates with the axial skeleton via the acromioclavicular joint at the distal clavicle and the sternoclavicular joint at the proximal end of the clavicle. The glenohumeral joint is deepened by the glenoid labrum, which is a ring-like, fibro-cartilaginous structure. The static stability of the glenohumeral joint derived from the joint capsule. The capsule is weakest at the inferior aspect, where it is also not reinforced by rotator cuff muscles. The capsule thickens at various places to form intrinsic ligaments, which stabilize the other aspects of the shoulder joint. Three glenohumeral ligaments (superior, middle and inferior) reinforce the anterior aspect of the capsule. The transverse humeral ligament bridges the greater and lesser tubercles, securing the tendon and sheath of the long head of the biceps brachii in the intertubercular groove. Dynamic stability of the glenohumeral joint depends primarily on the rotator cuff muscles – supraspinatus, infraspinatus, teres minor and subscapularis. Supraspinatus, innervated by the suprascapular nerve (C4, C5, C6) originates on the supraspinous fossa of the scapula and inserts on the superior facet of the greater tubercle of the humerus.[5] Infraspinatus, innervated by the suprascapular nerve (C5, C6), originates at the infrspinous fossa of the scapula and inserts at the middle facet of the greater tubercle of the humerus.[5] Teres minor, innervated by the Axillary nerve (C5, C6), originates on the middle part of the lateral border of the scapula and inserts at the inferior facet of the greater tubercle of the humerus.[5] Subscapularis, innervated by the upper and lower subscapular nerves (C5, C6, C7), originates at e subscapular fossa and inserts at the lesser tubercle of the humerus.[5]
http://jimmysmithtraining.com/wp-content/uploads/2009/10/shoulder_anatomy_ant_muscle.jpg
Clinical Presentation
- Anterior Instability: Shoulder girdle often droops, and excessive scapulothoracic movement may occur on abduction.[4]
- Posterior Instability: horizontal adduction (cross-flexion) may cause excessive scapulothoracic movement. Any apprehension on movement suggests the possibility of instability.[4]
- MDI (Multidirectional Instability): can be identified as shoulder instability in more than one plane of motion. [3]
Examination
Postural examination
The first step in a shoulder examination is to observe the shoulder joint. Amount and quality of movement should be assessed during gait, standing and sitting postures, and during other important activities. The shoulder should also be examined for deformity and alignment, swelling, atrophy, and rubor. In ideal posture, the auditory meatus should line up with the tip of the acromion and greater trochanter of the femur.
Elements of postural observation
- Step deformity: looking from an anterior view, the examiner should look for a ‘step deformity”, which may be caused by acromioclavicular dislocation. This deformity is present if the distal clavicle lies superior to the acromion process. If evident at rest, the step deformity indicates that both the AC and CC ligaments have been torn. If swelling is evident anterior to the AC joint, this is known as Fountain Sign, which indicates degernation at the AC joint and swollen subacromial bursa.
- Sulcus sign (for description for test, see below in Special Tests Section)
- Look for Scapular Winging:
- Dynamic winging (scapular winging with movement) can indicate “a lesion of the long thoracic nerve affecting serratus anterior, trapezius palsy (spinal accessory nerve), rhomboid weakness, multidirectional instability, voluntary action, or a painful shoulder resulting in splinting of the glenohumeral joint, which in turn causes reverse scapulohumeral rhythm.”[4]
- Static winging of the scapula is usually an indication of a structural deformity of the scapula, clavicle, spine or ribs.
- Palpate and take note of the following: [4]
- Calor/temperature
- Tenderness to Palpation (TTP)
- Swelling (may be difficult to see in the shoulder)
- Sensation
- Shoulder joint structures
- Pulses
- Crepitus
- Assess Biceps tendon
- Rotator Cuff Muscles
- Posterior Capsule
Clearing Joints Above and Below
During exam, clear the joints above and below the shoulder to confirm the area in which the symptoms are referring:
- Neck:
- Ext with resistance
- Rot B with resistance
- LCx B with resistance (lower cervical quadrant)
- Elbow:
- Flex with resistance
- Extend with resistance (stabilize GH and elbow)
If symptoms radiate to the hand, clear the wrist and hand:
- Wrist:
- Flex with resistance
- Extend with resistance
- Pronate with resistance
- Supinate with resistance
- Hand:
- Patient grips therapist hand
Range of Motion Testing
| Action | Normal Values | Primary Muscle(s) Involved |
|---|---|---|
| Abduction | 180⁰ | middle deltoid, supraspinatus |
| Flexion | 180⁰ | anterior deltoid |
| Extension | 60⁰ | posterior deltoid, teres major, latissius dorsi |
| External Rotation | 90⁰ | infraspinatus, teres minor |
| Internal Rotation | 70⁰ | subscapularis |
| Glenohumeral to scapulo-tharocic | 2:1 |
Manual Muscle Testing
Perform a shoulder manual muscle test to determine if patient problems are causing muscle weakness.[2]
- Flexion - Patient is short sitting with their arm flexed to 90 degrees. Examiner applies downward force over distal humerus just above the elbow.
- Extension - Patient is prone with elbow extended arms at side. Patient raises arm off of table. Examiner applies downward force on the posterior arm just above the elbow.
- Abduction - Patient is short sitting with elbows extended and arms abducted to 90 degrees. Examiner applies downward force just above the elbow.
- Horizontal Abduction -Patient is prone with shoulder abducted to 90 degrees and forearm off the edge of the table, elbows flexed 90 degrees. Patient horizontally abducts while examiner provides downward resistance over posterior arm just above the elbow.
- Horizontal Adduction -Patient is supine with shoulder abducted to 90 degrees and elbow flexed to 90 degrees. Patient horizontally adducts while examiner provides resistance around the forearm proximal to the wrist.
- External Rotation - Patient is prone with shoulder abducted to 90 degrees (arm supported on the table with towel roll under distal humerus). Patient moves arm through external rotation. Examiner uses two fingers to give resistance at the wrist while supporting the elbow.
- Internal Rotation - Patient is prone with shoulder abducted to 90 degrees (arm supported on the table with towel roll under distal humerus). Patient moves arm through internal rotation. Examiner uses two fingers to give resistance at the wrist while supporting the elbow.
Neurological Testing
Neurological testing should be performed in order to determine if patient problems involve diminished neurological sensation or motor control.
- Reflexes:
- C6: biceps: place thumb on bicep tendon & hit thumb with reflex hammer
- C7: triceps: test proximal to elbow, upper extremity is relaxed. Can be performed with arm supported by examiner, shoulder at 90 degrees of abduction, passive full internal rotation and elbow relaxed at 90 degrees of flexion (hanging towards ground)
- Test Myotomes: (seated)
- C1/C2: Neck flexion
- C3: Bilateral cervical neck side bending
- C4: Shoulder Shrug
- C5: Shoulder Abduction
- C6: Elbow Flexion / Wrist extension
- C7: Elbow Extension / Wrist flexion
- C8: Thumb extension / Finger flexion
- T1: Finger abduction
- Test Dermatomes: (seated or supine)
- C4: tip of shoulder
- C5: radial side of wrist
- C6: radial side of thumb
- C7: index / middle finger
- C8: ulnar border of hand
- T1: medial forearm
- T2: medial upper arm
Neural Tension Tests
Neural tension tests should be performed to determine if the cause of the patient problem can be reproduced.
Upper Limb Tension Tests (ULTT) (Contraindication: shoulder dislocation or adhesive capsulitis)
- ULTT #1 (Nerve Root C5-7) All brachial nerves with median nerve bias steps: (Baseline test – always go here when sxs are vague)
- Stabilize Shoulder (fist above shoulder) to prohibit scapular elevation
- Elbow Flexion
- GH Adb ~ 110 degrees
- GH LR
- Full forearm supination
- Full active wrist & finger extension c OP
- Full elbow extension
- Cervical Lateral flex away (increase tension) & towards (decrease tension)
- ULTT #2A (Median nerve bias) steps:
- Pt positioned diagonaly on plinth with shoulder angled towards examiner
- Depress scapula
- Extend elbow c forearm in “anatomical position”
- LR entire UE (shoulder LR & Forearm supination)
- Extend wrist & fingers
- Abd shldr
- Cervical Lateral flex away and towards
- ULTT #2B (Radial nerve bias) steps:
- Pt positioned diagonaly on plinth with shoulder angled towards examiner
- Depress scapula
- Extend elbow c forearm in “anatomical position”
- MR entire UE (shoulder MR & Forearm pronation)
- Flex thumb & fingers
- Wrist flex and ulnar dev
- Abd sldr
- Cervical Lateral flex away & towards
- ULTT #3 (Ulnar nerve bias) steps:
- Elbow Flex
- Forearm pronation
- Wrist extension (emphasize ulnar side)
- Lateral Rptation of shoulder
- Abduction of shoulder
- Cervical Lateral flex away & towards
Special Tests
Tests for Capsular/Ligament Stability
Sulcus Sign
The primary complaint of patients with inferior instability is pain rather than a feeling of instability. Their symptoms are usually in the midrange and may present with transient neurological symptoms.[4] [6]
- Purpose: indicate inferior instability or glenohumeral laxity.
- Patient Position: sitting with shoulder in neutral or in 20-50 degrees of abduction, elbow at 90 degrees.[4]
- Technique: examiner palpates shoulder joint line while using proximal forearm as a lever to inferiorly distract humerus. Magee recommends that the test be done in the position in which the patient reports feeling the sensation of instability.
- Interpretation: + test = >= 1 finger-widtch gap at the shoulder joint line or AC joint. The sulcus sign is graded as indicated in the table below. [4]
*Inter-examiner reliability (ICC): .60
*Kappa value: < 0.5 [7]
| Distance from inferior acromion to humeral head | Grade |
|---|---|
| Less than 1 cm | +1 |
| 1-2 cm | +2 |
| More than 2 cm | +3 |
Anterior Drawer
- Purpose: Excessive laxity at 45 degrees suggests pathology of anterior band of MGHL and excessive laxity at 90 degrees suggests pathology of the anterior band of the IGHL.
- Patient Position: Supine with shoulder abducted at 45 and 90 degrees.
- Examiner Position: Standing on the side of the shoulder to be tested.
- Technique: Performed at 45-90 degrees. Apply traction of the humerus in the glenoid fossa. Stabilize scapula and elbow. Examiner grabs humeral head and slides humeral head anterior.
- Reliability is unknown, however inter-observer reliability (ICC) of the sulcus sign and laxity tests using Altchek’s grading system was 47% with a kappa value of less than 0.5.[7]
Posterior Drawer
- Purpose: Assessment of posterior ligament laxity
- Patient Position: Supine with shoulder abducted at 45 and 90 degrees.
- Examiner Position: Standing on the side of the shoulder to be tested.
- Technique: Performed at 45-90 degrees. Apply traction of the humerus in the glenoid fossa. Stabilize scapula and elbow. Examiner grabs humeral head and slides humeral head posterior.
- An analysis of the inter-observer reliability of the sulcus sign and the laxity tests using Altchek’s grading system showed that overall reproducibility was 47% with a kappa value of less than 0.5. The intra-observer reproducibility was only 47%. Most of this discrepancy was with grades 0 and 1. When these grades were combined, the intra-observer reproducibility increased to 73%.[8]
Load and shift test
- Purpose: Assessment of atraumatic instability problems of the glenohumeral joint.
- Patient Position: sitting with proper posture (i.e. ear lobe, tip of acromion, and high point of iliac crest in a straight line) with no back support, with hand of test arm resting on thigh as relaxed as possible.
- Examiner Position: Standing behind patient and stabilizes shoulder with one hand over the clavicle and scapula.
- Technique: Using the non-stabilizing hand, the examiner grasps the head of the humerus with the thumb over the posterior humeral head and the finger over the anterior humeral head. The examiner runs the fingers along the anterior humerus and the thumb along the posterior humerus to feel where the humerus is seated relative to the glenoid. If the fingers dip in anteriorly as the move medially, but the thumb does not, it indicates the humeral head is sitting anterior. Normally, the humeral head feels a bit more anteriorly when it is properly seated in the glenoid. Protraction of the scapula causes the glenoid head to shift anteriorly in the glenoid.
- “Load” portion of the test: The humerus is gently pushed anteriorly or posteriorly (most common) in the glenoid if necessary to seat it properly in the glenoid fossa. The seating places the head of the humerus in its normal position relative to the glenoid. If the load is not applied, there is no normal or standard starting position for the test.
- “Shift” portion of the test: The humeral head is pushed anteriorly (for anterior stability) or posteriorly (for posterior stability), noting the amount of translation and end feel.
- Interpretation: >= 25% is a positive test; For posterior translation, 50% of humeral head translation is considered normal, though results may vary.
*The reliability of this test was found to be optimal when tested in 0 abduction for the posterior and inferior (intra-class correlation coefficient (ICC), for inter-rater reliability and test-retest reliability was 0.68 and 0.79, respectively). By abducting to 90, the anterior direction reliability is also good (ICC: 0.72).[7]
Apprehension and Relocation tests (AKA Fowler sign or Jobe relocation test)
- Purpose: Assessment of traumatic instability causing gross or anatomical instability of the shoulder, although the relocation portion of the test is sometimes used to differentiate between instability and impingement.
- Patient Position: Spine
- Examiner Position: Standing on the side of the test arm
- Apprehension Test Technique & Interpretation:
- Technique: Standing on the side of the test arm, provide minimal stability at the GH joint. (Note: Provide just enough pressure to feel for the humeral head to dislocate.) Slowly abduct arm 90 degrees then laterally rotate the shoulder slowly.
- Interpretation: A positive Apprehension test is indicated by a look of apprehension or alarm by the patient.
- Specificity: SLAP: 63%, for any labral lesion including SLAP: 87%
- Sensitivity: SLAP: 30%, for any labral lesion including SLAP: 40%[4]
- Relocation Test Technique & Interpretation:
- Technique: Standing on the side of the test arm, palpate and provide a stabilizing force to the GH joint, to prevent the humeral head from dislocating. Slowly abduct arm 90 degrees then laterally rotate the shoulder slowly.
- Interpretation: A positive Relocation test is indicated by the decrease in pain or feeling of apprehension by the patient. In addition, any pain that is present commonly decreases and further lateral rotation is possible before the apprehension or pain returns.
- Specificity: 54.35%, for SLAP: 63%, for any labral lesion including SLAP: 87%
- Sensitivity: 45.83%, for SLAP: 36%, for any labral lesion including SLAP: 44%[4]
Tests for Labral Tears
Obrien’s Compression Test
Purpose: Detecting SLAP or superior labral lesions
Patient Position: Seated with shoulder flexed 90 degrees, and adducted 10-15 degrees, thumb down.
Examiner Position: Standing on the test arm side of the patient
Technique: Examiner applies a downward force to distal forearm, then instructs patient to fully supinate forearm. Examiner again applies a downward force to the distal forearm.
Interpretation: A positive test is pain with thumb down, and not with palm up.
Specificity: SLAP = 47%, for any labral lesion including SLAP: 73% ; for labral tear: 31%
Sensitivity: SLAP = 54%, for any labral lesion including SLAP: 63% ; for labral tear: 54%[4]
Biceps Load Test
Purpose: Determining the integrity of the superior labrum
Patient Position:Patient is supine, with shoulder in 90 degrees of abduction and elbow flexion palm supinated.
Examiner Postion: Standing on the test arm side of the patient
Technique: Examiner laterally rotates the shoulder, and asks for pain, and if no pain, the patient is asked to provide an elbow flexion force against the examiners resistance. This test is also performed at 120 degrees of abduction.
Interpretation: A positive test is pain in the subacromial space when the shoulder is laterally rotated or when the examiner applies resistance against patients elbow flexion force.
Specificity: 96.6%
Sensitivity: 98.91%[4]
Differential Diagnosis
Differentiating between AMBRI (shoulder instability that is Atraumatic, Multidirectional, frequently Bilateral, responds to Rehabilitation) and TUBS (shoulder instability that is Traumatic Unilateral, usually with Bankart lesion and usually requiring Surgery)[4]
| Factor | Shoulder Instability | Traumatic Anterior Dislocation |
|---|---|---|
| History | Feeling of shoulder slippage with pain; Feeling of insecurity when doing specific activities; No history of injury | Arm elevated and laterally rotated relative to body; Feeling of insecurity when in specific position (of dislocation); Recurrent episodes of apprehension |
| Observation | Normal | Normal (if reduced) (if not, loss of rounding of deltoid caused by anterior dislocation) |
| Active Movement | Normal ROM; May be abnormal or painful at activity speed | Apprehension and decreased ROM in abduction and lateral rotation |
| Passive Movement | Normal ROM; Pain at extreme of ROM possible | Muscle guarding and decreased ROM in apprehension position |
| Resisted isometric movement | Normal in test position; May be weak in provocative position | Pain into abduction and lateral rotation |
| Special Tests | May be weak in provocative position; Load and shift test is positive | Apprehension positive; Augmentation positive; Relocation positive |
| Reflexes and cutaneous distribution | Normal reflexes and sensation | Sensation normal, unless axillary or musculocutaneous nerve is injured |
| Palpation | Normal | Anterior shoulder is tender |
| Diagnostic imaging | Normal | Normal, unless still dislocated; defect possible |
Referred pain
“True shoulder pain rarely extends below the elbow. Pain at the acromioclaviduclar or sternoclavicular joint tends to be localized to the affected joint and usually does not spread or radiate. Pain can be referred to the shoulder and surrounding tissues from many structures, including the cervical spine, elbow, lungs, heart, diaphragm, gallbladder and spleen.” [4]
Image at: http://www.watkinson.co.nz/referred_pain_to_shoulder.htm
