clinical signs are sometimes misleading and radiography does not always provide a clear answer ; the diagnosis can therefore be missed . ulnar dislocation is often traumatic ; it is caused by a hypersupination of the forearm for a palmar dislocation , and hyperpronation for a dorsal dislocation . in 1777 , desault ( cited by albisson et al . , and caranfil ) was the first of several authors to describe a case of distal radioulnar dislocation , but neither the physiopathology nor a standard treatment for this type of lesion has yet been described . the patient , a 23 years - old , right handed metal worker , was admitted to our accident and emergency services for pain in the left wrist following a fall with forced flexion of the wrist . there was no swelling or instability on testing of the distal radioulnar joint ( druj ) . the diagnosis was missed on the initial x - rays , as the lateral view was not well aligned ( figure 1a and b ) . one month later , the patient attended our department , as he continued to have a painful wrist . the anterior surface of the wrist showed a hard , round and smooth abnormal protuberance , made evident on deep palpation . because of this atypical clinical presentation , a computed tomography ( ct ) arthrography of the wrist was requested in order to establish a diagnosis of ligamentous injuries . mri imaging was performed to assess both the distal radioulnar ligament and the extensor carpi ulnaris tendon . ( a and b ) x - ray image of the left wrist , ap and lateral view . the ct arthrogram showed a palmar luxation of the ulnar head located at the distal radioulnar joint ( figure 2 ) . the triangular fibrocartilage complex ( tfcc ) showed a perforation and irregularities on the palmar side . mri imaging confirmed the palmar luxation and showed an intact extensor carpi ulnaris tendon that was not displaced . , we found the tfcc to be completely detached from its medial insertion and interposed in the distal radioulnar space . the ulnar notch of the radius was of good quality but the ulna head , however , showed a grade iii chondropathy ( figure 3 ) . due to the young age of our patient , our goal was an anatomic reinsertion of the tfcc , with keeping salvage procedures open for the future if necessary . first , the tfcc was reinserted at its insertion of the ulnar styloid using a non - absorbable transosseous suture . reduction of the druj was then secured by two extra - articular k - wires . intra- and post - operative x - rays were satisfactory ( figure 4a and b ) . unfortunately , 1 k - wire was broken , and was left inside the distal radius . at 2-months follow - up , the patient presented a non - painful wrist with a pronation of 180 , supination of 155 and symmetrical flexion and extension . ( a and b ) post - operative x - rays , ap and lateral view . ( a and b ) final post - operative x - rays after hardware removal . isolated palmar dislocation of the ulnar head is an uncommon injury , which explains the scarcity of publications . this type of dislocation is generally associated with fractures of the forearm and distal radius , and seldom presents without an accompanying fracture . being difficult to diagnose , this injury goes generally unnoticed in 50% of cases at first presentation at the emergency department , notwithstanding a routine radiographic examination . a judicious clinical examination will note an absence of the ulnar styloid at the dorsal surface of the wrist if present . however , radiographic imaging of the wrist is not always easy to interpret , especially if correct positioning of the wrist and forearm is not possible due to pain . ct arthrography of the wrist   and mri imaging are the preferred diagnostic tools , being able to diagnose both the dislocation and permitting a complete assessment of any adjacent ligamentous injury . rapid reduction of reducible dislocations offers a good prognosis , as is shown in a case series of mulford et al . . eleven closed reductions in a total of nine patients were performed the same day as presentation at the emergency department . early diagnosis seems to influence the treatment . singletary   reports on a case of early diagnosis of palmar dislocation of the druj in a 39 year - old patient . kumar   also reports on a case seen after a 3-day delay in diagnosis , which was successfully treated by closed reduction . in these cases caranafil describes a 27 year old patient with a 10-week delayed diagnosis and an unsuccessful open reduction that was the reason for an ulnar head resection according to darrach . in this case , the interposition of the tfcc ligament in the distal radioulnar joint was the reason for the failure of closed reduction , as also described by ellanti and grieve . p ellanti and pp grieve , consider the repair of the tfcc as the most important factor for obtaining a stable reduction of a chronic dislocation . takahashi et al . , confirmed the presence of an adjacent tfcc lesion by wrist arthroscopy . on the other hand , only mcmurray and muralikkutan   mention an absence of damage to the tfcc on mri imaging in his case report of an irreducible druj dislocation . , who describe a 73 years - old female patient whose closed reduction ended in a failure and underwent a sauv all of the above permits us to emphasize , as does caranafil , the concept of either a simple or complex dislocation : a simple dislocation is easily reduced by external manipulation and remains stable . a complex dislocation is characterized by instability , recurrence or irreducibility , caused by the interposition of soft tissues , especially the tfcc . isolated palmar dislocation of the distal radioulnar joint is a rare lesion of which the diagnosis is difficult to establish . the x - rays are sometimes non - conclusive ; therefore , only a ct arthrogram or mri can confirm the diagnosis . we would like to stress that even after a late diagnosis ; a good result can be obtained by open reduction and repair of the tfcc ligament . the authors report no conflicts of interest . the authors alone are responsible for the content and writing of the paper .
a rare case of an isolated traumatic palmar dislocation of the distal radioulnar joint is presented . clinically , there is a loss of pronation and supination . 
 the dislocation was treated using an open reduction , reinsertion of the capsule - ligamentous complex and temporary stabilization using k - wires .