Introduction Axillary nerve and posterior humeral circumflex artery compression in the quadrilateral (quadrangular) space Epidemiology incidence rare and often misdiagnosed as subacromial impingement demographics 20-40 years old location most commonly affects the dominant shoulder risk factors overhead movement athletes (e.g. basketball) contact or throwing sports Pathophysiology mechanism of injury compression and reduction of quadrangular space due to iatrogenic (tight fibrous bands, muscular hypertrophy) paralabral cysts (most commonly inferior labral tears) trauma (scapular fracture, shoulder dislocation) benign or malignant masses pathomechanics greatest amount of compression occurs when the arm is positioned in the late cocking phase of throwing (abduction and external rotation) Prognosis long-standing cases often causes atrophy/weakness of teres minor and deltoid Anatomy Quadrangular space location lateral to triangular space and medial to triangular interval boundaries superior - subscapularis and teres minor inferior - teres major medial - long head of triceps brachii lateral - surgical neck of the humerus contents axillary nerve (C5 nerve root, posterior cord) posterior circumflex humeral artery Presentation Symptoms poorly localized pain of the posterior/lateral shoulder often worse at night worse with overhead activity or late cocking/acceleration phase of throwing non-dermatomal distribution of paraesthesia along the lateral shoulder and arm shoulder external rotation weakness Physical examination inspection may see atrophy of the teres minor and deltoid palpation point tenderness over the quadrangular space motion and strength external rotation weakness with the arm abducted in throwing position pain exacerbated by active and resisted abduction and external rotation of the arm neurological examination usually normal have mild sensory changes in the axillary nerve distribution Imaging Radiographs recommended views shoulder series (AP, lateral, axillary views) findings usually normal used to rule out pathologic entities MRI indications often used to rule out rotator cuff pathology findings may show atrophy of teres minor (axillary innervation) may show compression of the quadrilateral space may show inferior paralabral cyst associated with labral tear Arteriogram may shows lesion in posterior humeral circumflex artery EMG indications used to confirm diagnosis findings will show axillary nerve involvement Treatment Nonoperative NSAIDS, activity restriction, physiotherapy indications first line of treatment techniques glenohumeral joint mobilization and strengthening posterior capsule stretching massage outcomes most people improve with 3-6 months of nonoperative treatment diagnostic lidocaine block indications will help to confirm diagnosis technique inject plain lidocaine directly into the quadrilateral space starting point is 2 to 3 cm inferior to the standard posterior shoulder arthroscopy portal outcomes positive if no point tenderness or pain with full ROM of the shoulder following injection Operative nerve decompression indications failure of nonoperative management significant weakness and functional disability decompression of space-occupying lesion techniques open release of quadrilateral space +/- arthroscopic repair of labral tear Surgical Techniques Open Quadrilateral Space Decompression approach lateral decubitus position 3 - 4 cm incision over the quadrilateral space identify posterior border of deltoid and reflect superolateral expose fat in quadrilateral space between teres minor and teres major technique identify the axillary nerve by using the humeral neck as reference avoid cutting the posterior circumflex artery free any fibrous lesions adhering to the nerve ensure the nerve is completely free of compression by moving the arm into abduction and external rotation postoperative care immediate sling for comfort early pendulum exercises to avoid new adhesions progress to full active ROM with supervised physiotherapy
QUESTIONS 1 of 4 1 2 3 4 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ09.72) A professional baseball pitcher develops shoulder pain, weakness and lateral arm paresthesias in his throwing arm. Selected MRI images of the right shoulder are shown in Figures A and B. What is the diagnosis? Review Topic QID: 2885 FIGURES: A B 1 Parsonage-Turner syndrome 7% (140/2138) 2 Long thoracic neuritis 0% (6/2138) 3 Quadrilateral space syndrome 89% (1893/2138) 4 Internal impingement 3% (69/2138) 5 External impingement 1% (19/2138) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ08.133) An MRI of the shoulder in a patient with chronic quadrilateral space syndrome is most likely to show which of the following? Review Topic QID: 519 1 Increased intra-capsular volume 2% (20/1270) 2 Loss of intra-capsular volume 2% (24/1270) 3 Fatty atrophy of the infraspinatus 4% (45/1270) 4 Fatty atrophy of the teres minor 90% (1148/1270) 5 Fatty atrophy of the latissimus dorsi 2% (27/1270) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ10.233) A 24-year-old patient complains of vague right shoulder pain. On physical exam the patient is noted to have weakness with external rotation. EMG findings are consistent with quadrilateral space syndrome. Along with the deltoid, what other muscle is affected? Review Topic QID: 3332 1 Teres major 10% (194/1969) 2 Teres minor 87% (1716/1969) 3 Pectoralis major 1% (13/1969) 4 Supraspinatus 1% (17/1969) 5 Subscapularis 1% (22/1969) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 2