The Shoulder Lock test is used to help differentiate the cause of symptoms when the patient complains of localized catching shoulder pain, and pain or restricted movement, when attempting to place the hand behind the back.
The lock position compresses the subacromial space and reproduces pain with shoulder impingement syndrome.
This test is done along with quadrant position of shoulder.
How do you perform the lock test of the shoulder?
It is assumed that the techniques are performed on the patient’s right side:
The patient lies in the supine position with the right shoulder at the edge of the table, and the elbow positioned 10 degrees posterior to the frontal plane.
The clinician places his or her left hand under the scapula.
The clinician’s right hand is placed near the patient’s right elbow.
After assessing the resting symptoms, the clinician slowly glides the patient’s elbow anteriorly, noting the location of onset of resistance and/or pain in the available range.
The end position for the test is achieved when the patient’s right shoulder is in maximal humeral flexion with overpressure, and neither the patient nor the clinician can externally rotate the arm further while at this end range.
In the locking position, the greater tuberosity and its rotator cuff attachments are caught within the subacromial space.
Further motion into external rotation, flexion, or abduction is not possible, unless the arm is allowed to move into less flexion.
What is a positive lock test?
Positive findings for this test include reproduction of the patient’s symptoms and a decrease in ROM compared with the uninvolved shoulder.
Sensitivity & Specificity
Since the clinician controls the motion, this test can be a very sensitive test to help confirm the presence of an impingement of the supraspinatus tendon.
Quadrant Position of Shoulder
The quadrant position of shoulder stresses the anterior and inferior part of the shoulder capsule and indicates capsular tightening.
Quadrant’ Position is reached from the ‘locked’ position:
The examiner stabilizes the shoulder girdle, maintaining the elbow at about 90° flexion.
The pressure maintaining abduction is slightly relaxed to allow the humerus to move anteriorly and to laterally rotate until the arm has reached full flexion.
A small arc of movement may be detected in this maneuver which resembles a ‘hill’ in the coronal plane.
The two tests refer to the position of the greater tuberosity related to acromial arch and glenoid.
locking position occurs when the greater tuberosity approximates a combination of the coracoacromial arch and coracoid process,
The quadrant position occurs when the greater tuberosity lies under the acromion.
Each test should be assessed for pain and end-feel, and should be compared with the uninjured side.
The results of this a study suggest that a number of pain sensitive structures may be involved, namely:
During ‘locking test’:
the supraspinatus tendon,
Where there is anteroinferior capsular tightness, movement may be restricted.
During ‘quadrant position’:
The supraspinatus tendon, coracoacromial ligament, glenoid labrum, acromioclavicular joint and subacromial bursa are implicated.
The tendon of long head of biceps, the superior, anterior and inferior fibres of the capsule, and, to a lesser extent, tendons of infraspinatus and subscapularis may also be involved.
Mullen F, Slade S, Briggs C. Bony and capsular determinants of glenohumeral ‘locking’ and ‘quadrant’ positions. Aust J Physiother. 1989;35(4):202-8. doi: 10.1016/S0004-9514(14)60508-0. PMID: 25025618.