An unusual cause of the quadrilateral space impingement syndrome by a bone spike

Abstract

The quadrilateral space impingement syndrome is a clinical syndrome resulting from compression of the axillary nerve and the posterior circumflex humeral artery, with subsequent focal atrophy of the teres minor, with or without involvement of portions of the deltoid muscle. This entity has many etiologies. We are reporting a case of this syndrome caused by a bone spike from a malunited old scapular fracture following a motor vehicle accident. The bone spike impinged on the axillary nerve as it passes through the quadrilateral space, causing focal atrophy of the teres minor muscle. The abnormality was well demonstrated by MD-CT.

Quadrilateral space syndrome: The forgotten differential

“…Following that, sporadic case reports ensued describing the various causes and presenting symptoms of QSS highlighting the difficulties in reaching a conclusive diagnosis. [2][3][4][5][6][7][8][9] We report a case of QSS masquerading initially as rotator cuff pathology with positive impingement signs. Clinical diagnosis of QSS is difficult to make because of the vague presenting complaint of shoulder pain coupled with shoulder weakness which is difficult to diagnose as deltoid and teres minor weakness can be masked by surrounding muscle groups that compensate for their function.…”

“…X-ray of the shoulder would be able to illustrate any joint or bony abnormalities such as fracture spikes or osteochondroma that can cause compression of the quadrilateral space. 4,5 In addition, MRI scan can evaluate the presence of soft tissue space occupying lesions such as paralabral cyst, aneurysm, neuroma, tumour or hypertrophied muscular boundaries. [1][2][3][6][7][8][9]11 Most importantly, by having the differential diagnosis of QSS in mind, the physician incharge can also specify to the radiologist to look out for pathologies at the quadrilateral space to improve sensitivity.…”

“…10 Several causes for internal compression within the quadrilateral space have been previously identified such as aneurysm, schwannoma and fibrous bands. [1][2][3][4][5][6][7][8][9]11 More common external compression causes include hypertrophied muscular boundaries, paralabral cysts, ganglion cyst and less common mechanical causes, such as an osteochondroma and a bony spike from malunion of a previous scapular fracture. [1][2][3][4][5][6][7][8][9]11 Compression may also be functional, with compression of the neurovascular structures in abduction and external rotation.…”

Arthroscopic Transcapsular Axillary Nerve Decompression

“…To this end, existing literature indicates fibrous bands, venous distention, muscular hypertrophy, or space occupying lesions can result in this type of compression. [1][2][3][4][5][6][7] Traditionally, these lesions have been decompressed using a posterior deltoid reflecting approach. 1,2,7,14 Using this technique, Cahill and Palmer reported significant symptomatic relief in 16 of 18 patients.…”

“…1,2 Fibrous bands are reported to be the most frequent compressive etiology, however malunited fractures, malignancies, humeral osteophytes, and hypertrophied musculature are also occasionally implicated. [1][2][3][4][5][6][7] Quadrilateral space syndrome typically afflicts active patients between the ages of 20 and 40 years. 8 Patients typically present with vague posterolateral shoulder pain and occasionally report declining athletic performance.…”