posterior dislocation of the shoulder accounts for 1%4% of all dislocations , while posterior fracture dislocations contributed to 0.9% of the 1500 dislocations observed by neer.2,3 the three main etiologies described in the literature are termed the  triple e syndrome  , which comprises epilepsy or any convulsive seizure , extreme trauma , and electric shock . seizures account for approximately 50% of all cases , trauma 45% , and electrocution less than 5%.4 posterior fracture dislocation of the shoulder itself presents with relatively uncharacteristic symptoms ; therefore , it is unsurprising that a precise initial diagnosis is usually missed . the main symptom observed is a reduction in movement of the affected shoulder , particularly loss of external rotation . the above injury can occur in patients with violent muscle contractions as in an epileptic fit when the bone architecture is affected by conditions like osteomalacia and osteoporosis . a 45-year - old caucasian male presented to the accident and emergency department with the chief complaint of bilateral shoulder pain , generalized aches , fatigue , and morning stiffness of 24 hours duration . he thought his pain was related to a series of low - intensity shoulder exercises including modern tai - chi , a traditional chinese exercise that he had performed the previous day . on the morning of admission , his family reported him to be vague , off - color , and similar to his appearance when he had a single witnessed seizure several years earlier . his past medical history included obesity and ischemic cardiomyopathy , for which he had had an automatic implantable cardioverter defibrillator inserted some years earlier . he was taking beta blockers and angiotensin - converting enzyme inhibitors , and denied alcohol and illicit drug use . musculoskeletal examination of the shoulders showed grade 3 tenderness and reduced movements in all planes . shoulder x - rays performed in view of his symptoms showed bilateral proximal humeral fractures ( figures 1 and 2 ) . a computed tomography scan of the shoulders confirmed a large impacted fracture of the left humeral head which was displaced posteriorly and a fracture of the anatomical neck of the right humerus with posterior dislocation ( figure 3 ) . a dual - emission x - ray absorptiometry ( dexa ) scan showed a t score of 2.6 at the lumbar spine and a t score of 1.2 at the hip . biochemical tests revealed normal calcium and phosphate levels , alkaline phosphatase raised at 264 iu / l ( normal 40140 iu / l ) , parathyroid hormone elevated at 9.1 pmol / l ( normal 0.45.5 pmol / l ) and 25-hydroxyvitamin d2 < 5 ng / ml ( low ) with 25-hydroxyvitamin d3 of 6.4 ng / ml ( < 10 ng / ml indicates severe deficiency and 1020 ng / ml indicates insufficiency ) . serum collagen type 1 cross - linked c - telopeptide was elevated above the normal range at 8 g / l ( 1.72  0.93 further investigations were initiated to confirm idiopathic epilepsy and neurology advice was sought , given that this was the second seizure . the automatic implantable cardioverter defibrillator was interrogated , which excluded ventricular tachyarrhythmia and malfunctioning of the device as a cause of his seizures . bilateral posterior fracture - dislocation is an uncommon orthopedic injury , with a peak incidence in middle - aged men.3 because the clinical manifestation varies greatly , it is often difficult to diagnose early . seizures are a well recognized cause of bilateral posterior fracture - dislocation of the shoulders . the mechanism of injury was reported by shaw in 1971.5 it is thought that during the convulsive episode , the shoulder is held in adduction , flexion , and internal rotation , and it is the contraction of the shoulder girdle muscles which force the humeral head superiorly and posteriorly . the final step in the process is due to infraspinatus , teres minor , deltoid , latissimus dorsi , and teres major , which provide the force necessary to produce dislocation . similarly , bilateral hip fracture can occur as a rare complication of seizures.6,7 vitamin d insufficiency is common in europe and asia . in 2010 , pearce and cheetam8 carried out a survey across the uk which demonstrated that more than 50% of the adult population have insufficient levels of vitamin d and that 16% have severe deficiency during winter and spring . the most at - risk groups include people with pigmented skin , the elderly , obese individuals , those with malabsorption , short bowel , or renal or liver disease , and individuals taking anticonvulsants or highly active antiretroviral drugs.9 in adults , vitamin d deficiency may present with musculoskeletal pain and weakness.9 low bone density on dexa scanning , or osteopenia on plain radiography , may also reflect osteomalacia , and these findings warrant assessment of vitamin d status,10 as demonstrated in our case . in our patient , the clinical findings coupled with the radiologic investigations confirmed the diagnosis of bilateral posterior fracture dislocation of the shoulders , which led us to identify a history of epileptic seizure and severe vitamin d deficiency . we believe that lack of sun exposure secondary to poor exercise tolerance as a result of morbid obesity and heart failure was the prime factor responsible for the vitamin d deficiency in our patient . the calcium levels were within normal limits , but the degree of vitamin d deficiency in this case was severe enough to cause low bone density and eventually increased bone fragility . normal calcium levels despite clear biochemical and radiologic evidence of established osteomalacia is often encountered as a physiologic consequence of secondary hyperparathyroidism , resulting in high parathyroid hormone levels and subsequent normalization of calcium levels in the blood . the combination of violent muscle contractions and low bone density were responsible for the simultaneous fracture of both humerus bones . despite uncharacteristic symptoms of fractures , prompt recognition and a focused investigation of the area concerned is important in order to minimize the risk of complications , which include nerve and vascular compromise . our patient made a satisfactory postoperative recovery and has been commenced on vitamin d supplementation . it is of the utmost importance to identify the cause of seizures , whether metabolic , cardiac , or cerebral . seizure management is necessary to prevent recurrence of the injury and further harm to the patient . though we recognize convulsive episodes as being the prime factor responsible for the mechanism of simultaneous bilateral fractures , bone fragility as a result of concomitant metabolic bone disorder should be studied actively in this type of presentation . screening for bone health , osteomalacia , and osteoporosis should be performed in all susceptible groups . prompt investigation and treatment of the underlying cause is necessary to prevent further fractures and long - term joint damage .
simultaneous bilateral posterior fracture dislocation of the shoulders is a rare clinical presentation . 
 there are three main etiologies described in the literature . given that it presents with relatively uncharacteristic symptoms , in many cases it is diagnosed late . 
 we present the case of a man who was admitted with bilateral posterior fracture dislocation of the shoulders following a seizure . 
 investigations revealed severe vitamin d deficiency as the principal contributory factor to his injury . 
 this is an important association because failure to recognize and treat this can result in significant morbidity in susceptible groups .