elbow fractures are among the most common traumatic injuries in the paediatric population , consisting of 15% of all paediatric fractures [ 1 , 2 ] .
humeral medial epicondyle fractures , in the paediatric population , account for up to 20% of elbow fractures , 60% of which are associated with an elbow dislocation .
the chance of median and ulnar nerve injuries , an incarcerated fragment in the joint , as well as other complications , further increases when a fracture is associated with a dislocation .
we present the case of a child who sustained a medial epicondyle fracture of the elbow , with a complete ulnar nerve palsy but without a joint dislocation , who was found intraoperatively to have ulnar nerve entrapment in the ulnohumeral joint .
the rare occurrence of complications relating to both acute and late ulnar nerve entrapments have been reported before in literature  including following supracondylar fractures , medial epicondyle fractures with elbow dislocations , forearm fractures and galeazzi fracture dislocations .
however , there have been no reports describing an ulnar nerve intra - articular entrapment , with a medial epicondyle fracture but without an elbow dislocation .
a 9-year - old girl presented to the emergency department with right elbow pain and swelling , after falling from a monkey bar onto her right elbow .
she had no history or clinical signs of an elbow dislocation , but she had a complete ulnar nerve palsy [ with the absence of sensation and increased 2-point discrimination , medical research council ( mrc ) sensation grading s0 ; mrc power grading 0/5 of intrinsic muscles of the hand , the little finger flexor digitorum profundus ( fdp ) and flexor carpi ulnaris ( fcu ) ; froment 's sign was positive ) , but there was no evidence of vascular compromise .
a plain radiograph showed that the medial epicondylar apophysis had been avulsed into the ulna humeral joint space , but there was no other fracture or dislocation seen ( fig . 
figure  1:plain radiographs of the injured right elbow : ( a ) anteroposterior view  and ( b ) lateral view .
plain radiographs of the injured right elbow : ( a ) anteroposterior view  and ( b ) lateral view .
she was taken directly to the operating theatre for emergency surgery , and an examination under anaesthesia revealed no elbow joint instability .
the ulnar nerve was not found in the anatomical position , so further exploration was undertaken .
the ulnar nerve was subsequently found to be trapped between the trochlea and proximal ulna , intra - articularly ( fig .  2 ) .
the medial epicondyle was also found avulsed from the humerus , with an incarcerated medial epicondylar fragment in the elbow joint .
the medial epicondyle was reduced to its anatomical position and fixed with a single cortical screw .
figure  2:intraoperative image showing the intra - articular entrapment of the ulnar nerve highlighted by the arrow .
intraoperative image showing the intra - articular entrapment of the ulnar nerve highlighted by the arrow .
a few hours post - operatively the sensation over the ulnar territory started to improve ( mrc grading s2 ) , fcu and fdp had partially recovered ( power improving to mrc grading 3/5 ) , but there was still mrc grading 1/5 of the intrinsic muscles of the hand . on the first post - operative day ,
the fcu and fdp were fully recovered with a mrc grading of 5/5 , but the intrinsic muscles of the hand remained weak . at 2 weeks
follow - up , the wound had healed well and the plaster was changed to an above elbow cylinder cast .
neurological examination of her hand revealed some still reduced sensation over the ulnar nerve territory , normal fcu and fdp function , with some further recovery of the intrinsic muscles of the hand ( mrc grading 3/5 ) . at 5 weeks follow - up , the plaster cast was removed and the patient had a good range of motion of the elbow , with no signs of instability .
she had a mrc grading of 5/5 of all the muscles , including the intrinsic muscles of the hand , and froment 's sign was negative , but there was still some reduced sensation ( mrc grading s3 ) .
follow - up , the patient had full range of movement of the stable elbow with completely recovered ulna nerve function .
figure  3:plain radiographs showing the healed fracture of the right elbow at 5 months : ( a ) anteroposterior view  and ( b ) lateral view .
plain radiographs showing the healed fracture of the right elbow at 5 months : ( a ) anteroposterior view  and ( b ) lateral view .
the contribution of the soft tissue structures around the elbow is of great importance in the stabilization of the elbow .
knowledge of the anatomy and biomechanics of the elbow , particularly the soft tissue and bony constraints , is of paramount importance in the diagnosis , management and long - term sequelae of injuries . in children ,
as the bony constraints of the elbow are not well developed , the stability of the elbow depends mainly on the soft tissue structures .
therefore , elbow dislocations in children will result in signs of damage of the soft tissue structures of the elbow .
however , open reduction with internal fixation of the epicondyle fragment is clearly indicated in cases of intra - articular entrapment of the fragment , on suspicion of entrapment of the ulnar nerve , or in cases of marked instability of the elbow . a medial epicondyle fracture associated with elbow dislocation , in children ,
may not be easily diagnosed on conventional radiographs because of the small size of the fragment , its  hidden position behind the distal humerus and the fact that it can be mistaken for the trochlear ossification centre . in the case presented , complete ulnar nerve palsy was present without any evidence of elbow dislocation in the history and with there being no signs of elbow instability intra - operatively .
prompt clinical assessment and surgical treatment confirmed the intra - articular ulna nerve position and avoided that a simple reversible neurapraxia further developed into an irreversible devastating nerve lesion .
 elbow fractures are not uncommon in children , and some are associated with neurovascular injuries . having a nerve injury in an elbow fracture without dislocation is rare and was not described in the literature . here , we have reported probably the first case of an ulnar nerve injury in an elbow fracture without dislocation . a 9-year - old female presented to the emergency department after falling off a monkey bar . 
 she had a painful , swollen and tender right elbow with no history or clinical signs of an elbow dislocation but had complete ulnar nerve palsy . 
 she was managed initially with analgesia and plaster application and was taken directly to the operating theatre . 
 examination under anaesthesia revealed no elbow joint instability . 
 the ulnar nerve was found entrapped between the trochlea and proximal ulna , intra - articularly . 
 the medial epicondyle was also found avulsed from the humerus , with an incarcerated medial epicondylar fragment in the elbow joint . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONFLICT OF INTEREST STATEMENT