CASE REPORT
~lar Molar Dislocation Dislocation of the Distal Distal Radioulnar Radioulnar Joint From the Department oj Emergency From the Department of Emergency Medicine, Eastern Eastern Virginia Medicine, Virginia Graduate Graduate School Medicine, Norfolk, NorJolk, Virginia. School oj of Medicine, Virg4nia.
Eunice EuniceM Singletary. Singletary,MD, FACEP FACEP
Received for Jar publication publication Received January 15, 1993. 1993. Revision receivedMay 10, 1O, 1993. 1993. Revision received Jar publication publication Acceptedfor May 27,1993. 27, 1993.
Emergency physicians occasionally encounter dislocations of the distal radioulnar joint when these are associated associated with fractures of the forearm. forearm, such as the Galeazzi fracture. fracture. Isolated dislocadislocations of the distal radioulnar joint without without fracture are rare and are described in terms of the position position of the ulna in relation to the radiocarpal joint. Radiographs may be difficult difficult to interpret if a a true lateral lateral view is not obtained. obtained. This injury may be easily missed in the emergency department because of its infrequent infrequent occurrence, occurrence, its relatively benign appearance, and difficulty difficulty in interpretation interpretation of radiographs. [Singletary EM: Volar dislocation of the distal radioulnar joint. April 1994;23:881-883.J Ann Emerg EmergMed April 1994;23:881-883.]
INTRODUCTION INTRODUCTION
Dislocation of the distal radioulnar radioulnar joint is most commonly ,2 Isolated dislocation associated with a forearm fracture. 11,2 of the distal radioulnar radioulnar joint is an infrequent injury, with - 11 A case of distal radioulnar few reported cases cases.22-11 radioulnar joint dislocation, ulna volar, is presented. CASE CASE REPORT REPORT
catching herself A 39-year-old woman tripped on stairs, catching with her left (nondominant) (nondominant) hand hand on the railing as she fell. She experienced immediate immediate pain in the wrist and presented to the emergency department department within a few hours complaining complaining of pain over the ulnar ulnar aspect of her wrist. She denied any history of wrist injury or any significant medical or surgical history. On examination, patient was holding examination, the patient holding her forearm supination. There was some prominence prominence noted over in supination. the volar surface of the wrist at the ulnar ulnar side and subtle loss of the normal normal prominence prominence of the distal ulna on the dorsal aspect as compared with the opposite wrist. Sensory examination examination showed that sensation was intact in the left hand, hand, and capillary refill was less than than two seconds in all fingers. The patient patient exhibited a full range of
APRIL 1994 1994 234 23:4 ANNALS OF EMERGENCY EMERGENCY MEDICINE MEDICINE ANNALS OF
881 981
VOLAR DISLOCATION Singletary
motion of her fingers, but flexion and extension at the wrist were limited and painful, and the patient was unable to pronate the wrist. Radiographs were obtained, demonstrating a complete volar dislocation of the distal ulna, without fracture (Figures 1 and 2). Orthopedic consultation was obtained, and closed reduction was performed by applying digital pressure on the distal ulna while pronating the hand. The arm was immobilized; postreduction films revealed complete reduction of the dislocation. DISCUSSION DISOUSSION
Dislocation of the distal radioulnar joint may be missed 12 These dislocations usually in as many as 50% of cases. cases.12 are described by the position of the ulna in relation to the radius, such as "ulna dorsal" or "ulna volar."3 volar. ''3 The normal ulnar head articulates with the distal radius, lunate, and triquetrum. It is separated from the lunate and triquetrum by an articular disk, a portion of the triangular fibrocartilage complex. The ulnar aspect of the distal radius has a concave joint surface, the sigmoid notch, which articulates with the distal ulna as the ulna.X3 13 radius rotates around the ulna. Volar dislocations of the ulna are due to forced forced hypersupination of the wrist, tearing the dorsal radioulnar ligament. 44 Clinically, the usual prominence of the ulnar head disappears, but this may be quite subtle unless
compared with the opposite wrist. Prominence over the volar surface of the distal ulna is more easily recognized. Flexion and extension movement of the wrist may not be painful, 1° although in this case and others 11 11 it is painful,lO restricted and uncomfortable. Pronation is typically not possible. 11 11 This injury may be visualized with anteroposterior and lateral radiographs. The anteroposterior view is obtained with the patient sitting, the hand and wrist held in neutral rotation, the elbow flexed 90 degrees, and the shoulder abducted 90 degrees. The x-ray beam is centered on the wrist and perpendicular to the cassette. A normal anteroposterior view of the wrist shows a 2- to 3-mm 3-ram distal radioulnar joint, whereas volar dislocation of the distal radioulnar joint results in overlap of the distal radius and ulna or an overall narrowed joint appearance (Figure 1). Dorsal dislocajoint may show widening tion of the distal radioulnar joint or diastasis of the joint. 13 13 A lateral view of the wrist is obtained with the forearm again in neutral rotation and the elbow flexed 90 degrees but with the arm at the side. The cassette lies under the ulnar aspect of the wrist and hand, and the x-ray tube is positioned directly above the wrist. 14 14 Figure Figure 2.
Lateral view. view. The distal ulna is displaced displaced anteriorly. anteriorly.
Figure Figure 1.
Anteroposterior view. view. Note overlap of the distal ulna on the radius. radius.
882 982
ANNALS OF EMERGENCY EMERGENCY MEDICINE MEDICINE 234 23:4 APRIL 1994 ANNALS OF
VOLAR V O L A R DISLOCATION DISLOCATION Singletary Si~gletary
If a true lateral view of the wrist is obtained, the capitate tare appears to sit at the base of the third metacarpal, its convex proximal surface articulates with the lunate, and the lunate articulates with the radius. A straight line then can be drawn along the axis of the third metacarpal, capitate, lunate, and radius. The distal radius is normally superimposed on the distal ulna in this view. 14 ]4 Rainey12 Rainey 12 suggests that when there is superimposition of the ulnar four metacarpals, a true lateral view has been obtained. Mino 14 > notes that a true lateral wrist film shows superimposition of the proximal pole of the scaphoid on the lunate and triquetrum, and the radial styloid appears centered over the lunate and proximal carpal row. Again, there should be complete ulnar overlap of the distal end of the radius. With volar dislocation of the distal radioulnar joint, the distal ulna instead appears displaced volar (anterior) to the radius on lateral radiograph (Figure 2). Unfortunately, Unfortunately, as little as 10 to 20 degrees of forearm rotation on the lateral view may significantly alter the normal appearance and even suggest radioulnar subluxation or dislocation when none exists. us exists.l,~5 Improper positioning for wrist radiographs because of pain or poor technique and inadequate visualization of bony detail because of overlying splinting or casting material contribute to the difficulty difficulty in making the diagnosis of distal radioulnar dislocation or subluxation in the ED. For these reasons, computed tomography has been found to be a useful means of visualizing this dislocation and is the diagnostic procedure of choice when plain radiography is inconclusive. 1L~4,16-~8 ,14,16-18 Usually, only one to three axial images are needed to make the diagnosis, and they may be done in any position of forearm rotation,14,16-18 rotation, ~4,~6-18 although Wechsler 18 ~8 suggests that images be done in both supination and pronation to avoid picturing a dynamic subluxation that is reduced. Reduction is accomplished by placing the forearm in pronation and immobilizing it for six weeks. Open necessary, particularly in cases of reduction may be necessary, 3 delayed diagnosis ,S,1O diagnosis. 3,5'1°
maintain a high index of suspicion for this uncommon and easily missed injury injury.
REFERENCES REFERENCES 1. AK, Levinsohn 1. Mino DE, DE, Palmer Palmer AK, Levinsohn EM: EM: The The role of radiography radiography and and computerized computerized tomography in the diagnosis of subluxation subluxatien and and dislocation of the distal radioulnar joint. J Hand HandSurg Surg1983; 1983; 8:23-31. 8:23-31. 2. Weseley MS, Barenfeld PA, PA, Bruno Bruno J: Volar dislocation distal radioulnar joint. J Trauma Trauma 1972;12:1083-1 088. 1972;12:1083-1088. 3. Dameron Dameron TB TB Jr: Traumatic dislocation of the distal radio-ulnar joint. Clin ClinOrthop Orthop1972;83:551972;83:5563. 63. 4. Axer A, Spann-Etzioni joint without Spann-EtzioniJ: Dislocation of the ulna at radio-ulnar joint without fracture of radius (report on Acta Med on 2 cases). cases). Acta Med Orient Orient1949;8:54-57. 1949;8:54-57. 5. 5. Paley Paley 0, D, Rubenstein Rubenstein J, McMurtry McMurtry RY: RY: Irreducible dislocation of distal radial ulnar joint. Orthop OrthopRev Rev1986;15:228-231. 1986;15:228-231. 6 AP: Anterior dislocation of the ulna at the inferior radio-ulnar joint. Case 6. Rose-Innes Rose-lnnes AP: Case reports. reports, with a discussion discussion of the anatomy of rotation of the forearm. J Bone BoneJoint Surg Surg1960;42:5151960;42:515521 521. 7. Darrach Ann Surg Darrach W: Anterior dislocation of the head head of the ulna. Ann Surg1912;56:802-803. 1912;58:802-803. 8. Hamlin C: Am J Sports C: Traumatic disruption of the distal radioulnar joint. Am SportsMed 1977;5:9397 97. 9. Heiple KG. KG, Freehafer Freehafer AA, Van't Hof A: Isolated traumatic dislocation of the distal end end of the ulna or distal radioulnar joint. J Bone BoneJoint Surg Surg1962;44:1387-1394. 1962;44:1387-1394. 10 Bone 10. Schiller MG, M6, Ekenstam Ekenstam F,F, Kirsch Kirscb PT: PT: Volar dislocation of the distal radio-ulnar joint. JJBone Joint Am 1991;73:617-619 Joint Surg SurgAm 1991;73:617-619. 11. 11. Francobandiera FrancobandieraC, C, Maffulli N. N, Lepore Lepore L:L: Distal radio-ulnar joint dislocation. dislocation, ulna volar velar in a female body builder.Med builder. Med Sci Sci Sports SportsExerc Exerc1990;22:155-158. 1990;22:155-158. 12. 12, Rainey Rainey RK. RK, Pfautsch Pfautsch ML: Traumatic dislocation of the distal radioulnar joint. Orthopedics Orthopedics 1985;8:896-900. 1985;8:896-900. 13. 13. Wood MB, Berquist TH: TH: The The hand hand and and wrist, in Berquist TH TH (edl: (ed): Imaging Imagingof Orthopedic Orthopedic Trauma Traumaand and Surgery. Surgery.Philadelphia, Philadelphia, WB Saunders Saunders Co, Co, 1986, 1986, p 641-730 641-730. 14. Mino DE, DE, Palmer AK, Levinsohn EM: Radiography and computerized tomography in in the diagnosis of incongruity incongruity of the distal radio-ulnar radio-ulnar joint. J Bone BoneJoint Surg Surg 1985;67-A:247252 252. 15. 15. Morrissey RT. RT, Nalebuff EA: EA: Dislocation of the distal radioulnar joint. Anatomy and and clues clues to prompt diagnosis. Clin ClinOrthop Orthop1979;144:154-158. 1979;144:154-158. 16. 16. Cone Cone RD. RO, Szabo Szabo R, R, Resnick Resnick 0, D, et al: ah Computerized Computerized tomography tomegraphy of the normal normal radioulnar joints. Invest InvestRadial Radial1983;18:541-545. 1983;18:541-545. 17. 17. Space Space TC. TO, Louis Louis OS, DS, Francis Francis I,I, et al: ah CT CT findings in distal radioulnar dislocation. J Comput Cemput Assist Tomogr Assist Tomegr1886;10:688-680 1986;10:689-690. 18. 18. Wechsler RJ, RJ, Wehbe MA. MA, Rifkin MD, et al: ah Computed Computed tomography diagnosis of distal radioulnar subluxation. Skeletal SkeletalRadio/1987;161-5. Radial1987;16:1-5.
Reprint no. 47/1/53849 Address for reprints: Eunice Eunice M Singletary, Singletary,MD, MD, FACEP FACEP Department Department of Emergency EmergencyMedicine Medicine Eastern Eastern Virginia Virginia Graduate GraduateSchool School of Medicine Medicine
SUMMARY SUMMARY The case of a woman who sustained a volar dislocation of her distal radioulnar joint is presented. Reduction of the dislocation was accomplished by using closed technique, and the joint was immobilized for six weeks. Clinicians evaluating patients with wrist injuries should
APRIL 1994
23:4
ANNALS OF OF EMERGENCY EMERGENCY MEDICINE MEDICINE
Raleigh Raleigh Building, Building,Room Room204 204 600 600 Gresham GreshamDrive Dive Norfolk, Norfolk, Virginia Virginia 23507-1999 23507-1999 804-628-3398 804-628-3398 Fax Fax804-628-2786 804-628-2786
883 8 83