Diagnosis of the direction of instability may be difficult if the patient is not seen with the shoulder dislocated. Accurate diagnosis is important to treat the instability correctly
About half of the patients with anterior instability never experience subjective instability; they complain exclusively of pain in the affected shoulder or a “ dead arm”.
The Apprehension test
Lateral rotation of the humerus at 45, 90 and 135 degrees of abduction, combined
At 45 degrees subscapularis and the middle glenohumeral ligament are stressed
At 90 degrees the inferior glenohumeral ligament is stressed.
The test may only be positive in this latter position in which subscapularis no longer exerts any control on the forwards and downwards movement of the humeral head.
Positive apprehension is often associated with a bony lesion or with a labral lesion at the antero-inferior rim of the glenoid.
Anterior drawer test of the shoulder
This is useful in detecting and grading capsular insufficiency of the capsular mechanism. It is used on more painful shoulders when apprehension testing is difficult to interpret.
Patient is supine, examiner facing the affected shoulder. He fixes the patients hand in his axilla. The shoulder is positioned in 80 to 120 degrees of abduction, 0 to 20 of forward flexion and 30 to 40 of lateral rotation.
The examiner should hold the scapula, pressing the scapular spine forwards with his index and middle fingers: his thumb exerts a counter pressure on the coracoid process.
The relaxed upper arm is then drawn forwards against the fixed scapula.
The relative movement between the fixed scapula and the moveable humerus can be appreciated and graded.
An occasional audible click on forwards movement of the humeral head is probably due to labral pathology and is usually associated with apprehension.
Recurrent dislocations occur either spontaneously or after significant trauma and are usually associated with anterior and/ or inferior instability . They account for a large proportion of voluntary dislocators.
The patient either voluntarily subluxates the shoulder in flexion and medial rotation or complains of weakness and instability in this position eg when doing press ups.
Posterior drawer test
Patient supine, examiner facing affected shoulder. Hold the proximal forearm and flex the elbow to 120 degrees, shoulder in 80 to 120 degrees of abduction and 20 to 30 degrees of forward flexion.
The scapula should be fixed with the index and middle fingers on the scapular spine, the thumb lies immediately lateral to the coracoid process.
The other hand slightly medially rotates the upper arm and forward flexes it to about 60 or 80 degrees. During this manoeuvre the thumb of the examiners other hand subluxates the humeral head posteriorly. This posterior displacement can be appreciated as the thumb slides along the lateral aspect of the coracoid process towards the glenoid and the humeral head butts against the ring finger of the examiners supporting hand.. This manoeuvre is often painfree but associated with a slight to moderates degree of apprehension.
Inferior instability is almost always a component of multi directional instability.
ROTATOR CUFF TESTING
Clinical diagnosis is based on the history and physical examination. Large rupture can be diagnosed with confidence, smaller lesions affecting a single tendon may be harder.
Mostly to test the malfunction of musculotendinous units at near maximal contraction
Posterior superior cuff- Jobe Sign- (supraspinatus and infraspinatus) This assesses the ability of the affected shoulder to maintain the arm in a position of 90 degrees of elevation in internal rotation against a force applied by the examiner. False positives may occur because pain may interfere with strength testing.
External Rotation lag sign
The patient is seated with his back towards the examiner.
The patient is then asked to actively maintain this position of external rotation in elevation as the examiner releases the wrist, while maintaining support at the elbow. The sign is positive when a lag or drop occurs.
The bigger the magnitude of the lag, the bigger the tear.
This test is designed to test the integrity of subscapularis and infraspinatus tendons.
Testing and interpretation are complicated by pathologic changes in the passive range of movement, eg reduced due to capsular contraction or increased due to subscapularis rupture .
The Drop Sign
Patient seated with back towards the examiner, who holds the affected arm at 90 degrees of elevation ( in the scapular plane) , elbow flexed to 90 degrees, almost full external rotation of the shoulder. In this position of external rotation, the maintenance is provided by infraspinatus..
The patient is asked to actively maintain this position as the examiner releases the wrist while supporting the elbow. A positive sign is when a lag occurs.
This is used to assess the integrity of infraspinatus.
Internal Rotation Lag Sign
Patient is seated with back towards the examiner, who holds the arm at almost maximal internal rotation, the elbow flexed to 90 degrees and the shoulder is held at 20 degrees of elevation and 20 of extension. The dorsum of the hand is passively lifted away from the lumbar region until almost full internal rotation is reached.
The patient is asked to actively maintain this position as the examiner releases the wrist while supporting the elbow.
An obvious drop occurs with large tears. A slight lag indicates a partial tear of the cranial part of the subscapularis tendon.
Tear of the subscapularis is usually caused by forced hyperextension (eg a fall onto an outstretched arm or forced ER from a seatbelt) or external rotation of the adducted arm. Persistent pain and weakness occur not only in activity above the head but also below.
Clinical signs are weakness of internal rotation with a pathological lift off test, increased passive external rotation, with an indistinct end point and pain at the extreme. Passive ER may produce some apprehension and pain which abduction reduces.
Repair of the ruptured tendon is technically demanding and required good exposure to identify and protect the axillary nerve, usually delto pectoral or superolateral.
The test places the muscle at the limit of the amplitude of contraction, i.e with the arm fully extended and internally rotated, the patient is unable to lift the arm away from the back of the lumbar region in this position.. This is termed a pathological lift off sign.