the course of the three major nerves crossing the elbow is quite consistent , yet in some instances variations are encountered particularly if the elbow has deformed following previous episode of fracture and surgery .
we present here a case of entrapment of radial nerve in the bone without any signs of nerve palsy resulting from an old supracondylar fracture of the humerus .
a 23-year - old male patient presented with cubitus varus deformity of the left elbow .
the patient developed the deformity following some fracture around elbow in the childhood at the age of 8 years that was managed conservatively in plaster cast after closed reduction .
on examination , the boy had 15 of cubitus varus deformity , full range of elbow movements , and no distal neural deficit .
radiograph showed an oblique joint line suggestive of varus deformity and evidence of old healed remodeled fracture line .
two foramina of 3 - 4 mm diameter were seen on anteroposterior view on a vertical plane .
the distal hole had a sharp margins while proximal had indistinct margins , similar holes were seen in oblique view [ figure 1 ] .
( a ) anteroposterior and ( b ) lateral radiographs of the elbow showing two foramina marked with black arrows this child was undertaken for lateral wedge corrective osteotomy at elbow , the lateral approach to the elbow between the flexor and extensor compartments was used to expose the site of osteotomy .
when the perisoteum from the anterior surface of the lower humerus was lifted , some anomalous structure entering into the bone was noticed on the medial side of the supracondylar region . on further dissection
it looked like neural tissue [ figure 2 ] , and was thought to be the median nerve .
we attempted to make a window into the bone and free the nerve but it was seen that the nerve was severely entrapped in the bone and on our repeated attempts to remove it , it got transected .
we planned to explore all the three nerves at the elbow to ascertain the identity of the nerve as its course was very aberrant .
post operatively the function of both ulnar and median nerves was normal , but there was radial nerve palsy [ figure 2a and b ] .
( a ) per - operative clinical photograph showing entrapped nerve in the bone and ( b ) the damaged radial nerve after attempts to remove it by cutting the bone the elbow was mobilized after 1 month . at 2 months
all implants were removed and tendon transfers for radial nerve palsy , namely , pronator teres to extensor carpi radialis brevis , palmaris longus to extensor pollicis longus , and flexor carpi radialis to extensor digitorum communis was done . with extensive physiotherapy ,
it is very unusual to find the radial nerve to be entrapped in the callus .
one such case was reported by symeonides et al.3 duthie1 has described a case of radial nerve palsy of long standing after a fracture of the shaft of the humerus in which the nerve was found to be enclosed in an osseous tunnel that was evident in the radiographs .
roaf2 referred to a case of median nerve paralysis of late onset after dislocation of the elbow with fracture of the medial epicondyle , which during healing created a tunnel ensheathing the nerve . in both cases
the nerve palsy indicated the correct diagnosis , which was supported by the radiographic findings . in our case
no such palsy existed and this led us to take it as a usual case .
this case is interesting because it had no preoperative nerve palsy , the unusual position of the osseous tunnel and the high risk of division or severe damage to the nerve .
we feel that before embarking on a reconstructive operation for post - traumatic cubitus varus , it is essential to examine the radiographs carefully for the presence of foramina suggestive of nerve entrapment , and if suspected , always explore the radial nerve at an early stage in the procedure .
 entrapment of a nerve in the callus of a healing fracture is not a common entity , but it does exist . 
 the entrapment usually presents without neurological deficit . 
 it is difficult to suspect the radial nerve injury if we need to operate on the same site . 
 we present a case of entrapment of radial nerve in the callus of a supracondylar humerus fracture with cubitus varus deformity . 
 the surgery for correction of the deformity led to the damage of the nerve . 
 in retrospect a careful assessment of the x - rays showed two 3 - 4 mm diameter holes . 
 awareness of this finding would have given us sufficient indication of nerve entrapment to prevent this mishap . 
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