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Hand Surgery, Vol. 19, No. 3 (2014) 413–417 © World Scientific Publishing Company DOI: 10.1142/S0218810414720277
A RARE COMBINATION: LOCKED VOLAR DISTAL RADIO-ULNAR JOINT DISLOCATION WITH ISOLATED VOLAR CAPSULE RUPTURE
Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Chris Yuk Kwan Tang, Jason Pui Yin Cheung and Boris Fung Department of Orthopaedics and Traumatology University of Hong Kong Medical Centre Queen Mary Hospital Received 28 December 2013; Revised 3 March 2014; Accepted 4 March 2014; Published 1 October 2014 ABSTRACT Distal Radioulnar Joint (DRUJ) dislocation is a commonly missed injury. A high clinical suspicion is required as the dislocation may not be obvious in the conventional views of radiographs. Volar DRUJ dislocations are far less common than the dorsal ones. Since triangular fibrocartilage complex (TFCC) is the major stabilizer of DRUJ, it is common that the irreducible DRUJ dislocation is associated with TFCC tear. We report a patient who had irreducible volar DRUJ dislocation blocked by the volar lip of sigmoid notch, with only isolated volar capsule rupture. Keywords: DRUJ; Locked; Dislocation; Volar; Capsule.
INTRODUCTION
significant impairment on daily activities such as opening a door. The stability of DRUJ is contributed by triangular fibrocartilage complex (TFCC) mostly,2 with the extensor carpi ulnaris subsheath and the interosseous membrane providing its static stability, and the pronator quadratus and the extensor carpi ulnaris muscles providing its dynamic stability.3 Isolated acute dislocation of the DRUJ is less common in comparison to those associated with fracture of radius or ulna, while there are far less isolated volar dislocations of DRUJ than dorsal dislocations. Volar DRUJ dislocations are commonly misdiagnosed, as many as 50% of cases.4 We report a case of volar DRUJ dislocation with failed closed reduction, subsequently managed by open reduction, but with only isolated volar capsule rupture.
The distal radioulnar joint (DRUJ) is unique as it is not a joint but a continuation of the forearm joint (a pivot joint, a type of synovial joint). The radius has a concave articulating surface distally (sigmoid notch) and a convex articulating surface proximally (radial head), whereas the corresponding ulna is the opposite, forming a bicondylar surface for pronation and supination. The sigmoid notch of radius has a diameter 1.5 times of the ulnar head, therefore during the 160 degrees of available pronation and supination, the distal radius actually performs a swing motion (or a translation) around the forearm axis of rotation (line joining the radial head to the fovea of the ulnar head). The proximal radius movement is a strict rotation around the axis.1 As a result, DRUJ dislocation affects both forearm pronation and supination, which has
Correspondence to: Dr. Jason Pui Yin Cheung, Department of Orthopaedics and Traumatology, 5/F Professorial Block, The University of Hong Kong Medical Centre, Queen Mary Hospital, Pokfulam, Hong Kong. Tel: (þ852) 2255-4581, Fax: (þ852) 2817-4392, E-mail: [email protected] 413
September 30, 2014
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CASE REPORT A 44-year-old man with good past health had an injury to his right wrist. A box of goods weighing approximately 30 kg fell from 5–6 meters and hit his right wrist dorsum directly. There were no other associated injuries. Clinically the right wrist was tender over the ulnar aspect (Fig. 1). There was limited wrist
Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
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Fig. 1
range of motion and absent forearm rotation. There was a sulcus over the ulna head prominence. X-rays showed no fracture but volar dislocation of the ulna head (Fig. 2). CT scan showed that the ulna head was volarly dislocated and was hinged at the palmar aspect of the sigmoid notch (Fig. 3). Closed reduction under sedation failed. Operation was performed under general anesthesia. Closed reduction under general anesthesia also failed. Volar approach to the DRUJ was performed and the ulna head was found to have ruptured through the volar capsule (Figs. 4–6). The DRUJ
Loss of ulna head prominence in volar DRUJ dislocation. Fig. 3
Fig. 2 Note the ulna is in volar position relative to the radius in volar DRUJ dislocation.
Fig. 4
Ulna was blocked by the volar lip of sigmoid notch in CT scan.
Diagram showing intact TFCC with torn volar DRUJ capsule.
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Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Locked Volar Distal Radio-Ulnar Joint Dislocation with Isolated Volar Capsule Rupture
Fig. 5 Diagram showing dislocated ulna head and torn volar DRUJ capsule.
Fig. 6
Diagram showing axial view of dislocated ulna and intact TFCC.
Fig. 7 Diagram showing direction of open reduction of DRUJ from volar approach.
Fig. 8
415
Torn DRUJ capsule was repaired by bone anchor sutures.
capsule was avulsed from the distal radius and there was a partial tear of the distal part of the pronator quadratus. Open reduction was performed and the capsule was repaired using 2 bone anchor sutures (Figs. 7 and 8). Stability was checked. Wrist arthroscopy was performed and found the TFCC to be intact both at the radial and ulnar side (sigmoid notch and fovea). Immobilisation by a hinge elbow brace with the forearm in neutral position for three weeks, followed by rehabilitation, was carried out after successful reduction. The patient subsequently enjoyed pain-free full range of motion (Figs. 9 and 10).
Fig. 9
Lateral view radiograph showing reduced DRUJ after operation.
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Fig. 10 Posteroanterior view radiograph showing reduced DRUJ after operation.
DISCUSSION Although terms such as volar or dorsal dislocation of the ulna at DRUJ are commonly used, it is important to be aware that the dislocation is actually caused by the displacement of the movable radius instead of the fixed ulna.5 As a result, volar DRUJ dislocation means that the ulna is in volar position with DRUJ dislocation, while dorsal DRUJ dislocation represents the dorsal position of the ulna. Volar DRUJ dislocations are commonly misdiagnosed, as many as 50% of cases,4 due to various reasons. Firstly, pronation and supination movements of forearm are not always examined, while the often tested flexion and extension movements of wrist are usually preserved. Secondly, local swelling at the wrist makes the usually ulnar prominence landmark ill-defined. Thirdly, the absence of fracture in radiographs gives a false reassurance that the wrist injury is minor. Isolated volar dislocation of DRUJ was first described by Cotton6 in 1912. In volar DRUJ dislocation, there is a history of hypersupination and the patients are unable to pronate their forearms.7–9 Another mechanism for volar DRUJ dislocation is a volarly applied force to the radius with a fixed ulna.6 On the other hand, in dorsal DRUJ dislocation, there is a history of hyperpronation, for example, a fall on the outstretched hand (hand is fixed by gravity to ground, but body with ulna rotates around the radius). In these injuries, patients are unable to supinate their forearms.7–9
Clinically, DRUJ stability is assessed by antero-posterior translation of the ulna on the radius in neutral, pronation and supination, with comparison to the contralateral side. With DRUJ dislocation, pronation or supination of forearm will usually be painful and limited.10 Morrissy recommended that both wrists should be inspected with the elbow in 90 degree flexion and forearm in neutral position.10 A dorsal prominence of the ulnar head should lead to the suspicion of dorsal DRUJ dislocation, while the presence of a hollow dorsally (at the usual site of ulnar head) points to volar DRUJ dislocation. In volar DRUJ dislocation, there is usually no ‘volar’ prominence of ulnar head due to the soft tissue bulk at the volar aspect of the wrist. However, the wrist looks narrower due to the compressive pull of pronator quadratus.11 Diagnosis should be confirmed by standardised radiographs. In the anteroposterior view, the patient’s hand is placed on the cassette with 90 degrees elbow flexion and shoulder abduction. The distal radioulnar joint is normally a 2–3 mm space in the wrist. As discussed above, the wrist will be narrower due to the pull of pronator quadratus in volar DRUJ dislocation, so there will be an overlap of the distal radius and ulna in anteroposterior radiographs of the wrist. The lateral radiographs should be taken by placing the patient’s ulnar forearm in neutral rotation on the cassette, with the elbow in 90 degrees flexion. Normally, the base of the third metacarpal, capitate, lunate and radius should be collinear, and the distal radius is superimposed on the ulna. In volar DRUJ dislocation, the distal ulna is displaced to the volar side.12,13 Regarding the choice of investigations for DRUJ, Mino12 carried out a prospective study that concluded with the following indications: in the absence of a deformity of the distal end of the radius, a lateral radiograph made with the wrist in the neutral position accurately revealed incongruency of the DRUJ joint. When pain or cast immobilization prevented optimum positioning of the wrist for radiography, or when a deformity of the distal end of the radius was present, computerised tomography (CT scan) gave a more accurate determination of the congruency of the joint. Stress radiographs included clenched-fist PA view in forearm pronation to assess DRUJ gap14 and weighted lateral stress view in pronation to assess instability.15 The CT scan performed in our patient was not for the diagnosis of the dislocation but for pre-operative planning of the reduction. Reduction of volar DRUJ dislocations require forcible pronation of the forearm with dorsally directed pressure on the
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Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Locked Volar Distal Radio-Ulnar Joint Dislocation with Isolated Volar Capsule Rupture
ulnar head under sedation or anesthesia. Open reductions after failed closed reduction had been previously described,16 the incidence of this is much higher for volar dislocations compared the dorsal ones. This may be due to pull of pronator quadratus in acute cases, contracted volar soft tissues in late cases, or interposition of torn dorsal radioulnar ligament.17 Garrugues18 previously described an irreducible volar DRUJ dislocation with distal ulna blocked by the volar lip of sigmoid notch of radius and TFCC tear. In our patient, the ulna was also blocked by the volar lip of sigmoid notch with only isolated volar capsule tear. This combination has not yet been described in the literature. Since TFCC is the major stabilizer of DRUJ, DRUJ dislocation is associated with high incidence of TFCC injury, especially in patients with failed closed reduction. Yet this did not happen in this patient. We postulated that this might be contributed by the partial tear of the pronator quadratus. As our patient was going to undergo open reduction for the DRUJ dislocation, wrist arthroscopy (the gold standard for diagnosing TFCC injury) was arranged in the same session, so that repair could be done if there was any injury to the TFCC. The DRUJ can be approached by a volar approach or dorsal approach. In the volar approach, the incision is just radial to flexor carpi ulnaris tendon. In a series of 51 patients, there were no significant complications reported.19 A volar approach was used in this case because the dislocation was in the volar side and TFCC repair could be done in case there had been a tear. Arthroscopy was carried out in the same session to look for TFCC tear in view of the high-energy mechanism of injury. In contrast, when the incision is made in line with the fifth extensor compartment in the dorsal approach, the dorsal sensory branch of ulnar nerve may be injured.20 In conclusion, DRUJ dislocation remains a commonly missed injury and a high index of suspicion is recommended. A full examination of wrist range of motion including pronation and supination, detailed search for DRUJ injuries in radiographs despite the absence of fractures, and addressing the underlying problem causing the irreducible DRUJ dislocation all constitute a better management of this entity.
References 1. Hagert E, Hagert CG, Understanding stability of the distal radioulnar joint through an understanding of its anatomy, Hand Clin 26(4):459– 466, 2010.
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2. Palmer AK, Werner FW, The triangular fibrocartilage complex of the wrist–anatomy and function, J Hand Surg Am 6(2):153–162, 1981. 3. Dalal S, Murali SR, The distal radio-ulnar joint, Orthop Trauma 26(1):44–52, 2012. 4. Rainey RK, Pfautsch ML, Traumatic volar dislocation of the distal radioulnar joint, Orthopedics 8(7):896–900, 1985. 5. Carlsen BT, Dennison DG, Moran SL, Acute dislocations of the distal radioulnar joint and distal ulna fractures, Hand Clin 26(4):503–516, 2010. 6. Cotton FJ, Brickley WJ, Luxation of the ulna forward at the wrist (without fracture): with report of a case, Ann Surg 55(3):368–374, 1912. 7. Rose-Innes AP, Anterior dislocation of the ulna at the inferior radioulnar joint. Case report, with a discussion of the anatomy of rotation of the forearm, J Bone Joint Surg Br 42-B:515–521, 1960. 8. Buterbaugh GA, Palmer AK, Fractures and dislocations of the distal radioulnar joint, Hand Clin 4(3):361–375, 1988. 9. Hui FC, Linscheid RL, Ulnotriquetral augmentation tenodesis: a reconstructive procedure for dorsal subluxation of the distal radioulnar joint, J Hand Surg Am 7(3):230–236, 1982. 10. Morrissy RT, Nalebuff EA, Dislocation of the distal radioulnar joint: anatomy and clues to prompt diagnosis, Clin Orthop Relat Res (144):154–158, 1979. 11. Bruckner JD, Alexander AH, Lichtman DM, Acute dislocations of the distal radioulnar joint, Instr Course Lect 45:27–36, 1996. 12. Mino DE, Palmer AK, Levinsohn EM, Radiography and computerized tomography in the diagnosis of incongruity of the distal radio-ulnar joint. A prospective study, J Bone Joint Surg Am 67(2):247–252, 1985. 13. Mittal R, Kulkarni R, Subsposh SY, Giannoudis PV, Isolated volar dislocation of distal radioulnar joint: how easy to miss!, Eur J Emerg Med 11(2):113–116, 2004. 14. Iida A, Omokawa S, Akahane M, Kawamura K, Takayama K, Tanaka Y, Distal radioulnar joint stress radiography for detecting radioulnar ligament injury, J Hand Surg Am 37(5):968–974, 2012. 15. Scheker LR, Belliappa PP, Acosta R, German DS, Reconstruction of the dorsal ligament of the triangular fibrocartilage complex, J Hand Surg Br 19(3):310–318, 1994. 16. Takami H, Takahashi S, Ando M, Isolated palmar dislocation of the distal radioulnar joint in a football player, Arch Orthop Trauma Surg 120(10):598–600, 2000. 17. Paley D, Rubenstein J, McMurtry RY, Irreducible dislocation of distal radial ulnar joint, Orthop Rev 15(4):228–231, 1986. 18. Garrigues GE, Aldridge JM, 3rd, Acute irreducible distal radioulnar joint dislocation. A case report, J Bone Joint Surg Am 89(7):1594–1597, 2007. 19. Bain GI, Pourgiezis N, Roth JH, Surgical approaches to the distal radioulnar joint, Tech Hand Up Extrem Surg 11(1):51–56, 2007. 20. Bain GI, Pugh DM, MacDermid JC, Roth JH, Matched hemiresection interposition arthroplasty of the distal radioulnar joint, J Hand Surg Am 20(6):944–950, 1995.
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Hand Surgery, Vol. 19, No. 3 (2014) 413–417 © World Scientific Publishing Company DOI: 10.1142/S0218810414720277
A RARE COMBINATION: LOCKED VOLAR DISTAL RADIO-ULNAR JOINT DISLOCATION WITH ISOLATED VOLAR CAPSULE RUPTURE
Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Chris Yuk Kwan Tang, Jason Pui Yin Cheung and Boris Fung Department of Orthopaedics and Traumatology University of Hong Kong Medical Centre Queen Mary Hospital Received 28 December 2013; Revised 3 March 2014; Accepted 4 March 2014; Published 1 October 2014 ABSTRACT Distal Radioulnar Joint (DRUJ) dislocation is a commonly missed injury. A high clinical suspicion is required as the dislocation may not be obvious in the conventional views of radiographs. Volar DRUJ dislocations are far less common than the dorsal ones. Since triangular fibrocartilage complex (TFCC) is the major stabilizer of DRUJ, it is common that the irreducible DRUJ dislocation is associated with TFCC tear. We report a patient who had irreducible volar DRUJ dislocation blocked by the volar lip of sigmoid notch, with only isolated volar capsule rupture. Keywords: DRUJ; Locked; Dislocation; Volar; Capsule.
INTRODUCTION
significant impairment on daily activities such as opening a door. The stability of DRUJ is contributed by triangular fibrocartilage complex (TFCC) mostly,2 with the extensor carpi ulnaris subsheath and the interosseous membrane providing its static stability, and the pronator quadratus and the extensor carpi ulnaris muscles providing its dynamic stability.3 Isolated acute dislocation of the DRUJ is less common in comparison to those associated with fracture of radius or ulna, while there are far less isolated volar dislocations of DRUJ than dorsal dislocations. Volar DRUJ dislocations are commonly misdiagnosed, as many as 50% of cases.4 We report a case of volar DRUJ dislocation with failed closed reduction, subsequently managed by open reduction, but with only isolated volar capsule rupture.
The distal radioulnar joint (DRUJ) is unique as it is not a joint but a continuation of the forearm joint (a pivot joint, a type of synovial joint). The radius has a concave articulating surface distally (sigmoid notch) and a convex articulating surface proximally (radial head), whereas the corresponding ulna is the opposite, forming a bicondylar surface for pronation and supination. The sigmoid notch of radius has a diameter 1.5 times of the ulnar head, therefore during the 160 degrees of available pronation and supination, the distal radius actually performs a swing motion (or a translation) around the forearm axis of rotation (line joining the radial head to the fovea of the ulnar head). The proximal radius movement is a strict rotation around the axis.1 As a result, DRUJ dislocation affects both forearm pronation and supination, which has
Correspondence to: Dr. Jason Pui Yin Cheung, Department of Orthopaedics and Traumatology, 5/F Professorial Block, The University of Hong Kong Medical Centre, Queen Mary Hospital, Pokfulam, Hong Kong. Tel: (þ852) 2255-4581, Fax: (þ852) 2817-4392, E-mail: [email protected] 413
September 30, 2014
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C. Y. K. Tang, J. P. Y. Cheung & B. Fung
CASE REPORT A 44-year-old man with good past health had an injury to his right wrist. A box of goods weighing approximately 30 kg fell from 5–6 meters and hit his right wrist dorsum directly. There were no other associated injuries. Clinically the right wrist was tender over the ulnar aspect (Fig. 1). There was limited wrist
Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
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Fig. 1
range of motion and absent forearm rotation. There was a sulcus over the ulna head prominence. X-rays showed no fracture but volar dislocation of the ulna head (Fig. 2). CT scan showed that the ulna head was volarly dislocated and was hinged at the palmar aspect of the sigmoid notch (Fig. 3). Closed reduction under sedation failed. Operation was performed under general anesthesia. Closed reduction under general anesthesia also failed. Volar approach to the DRUJ was performed and the ulna head was found to have ruptured through the volar capsule (Figs. 4–6). The DRUJ
Loss of ulna head prominence in volar DRUJ dislocation. Fig. 3
Fig. 2 Note the ulna is in volar position relative to the radius in volar DRUJ dislocation.
Fig. 4
Ulna was blocked by the volar lip of sigmoid notch in CT scan.
Diagram showing intact TFCC with torn volar DRUJ capsule.
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Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Locked Volar Distal Radio-Ulnar Joint Dislocation with Isolated Volar Capsule Rupture
Fig. 5 Diagram showing dislocated ulna head and torn volar DRUJ capsule.
Fig. 6
Diagram showing axial view of dislocated ulna and intact TFCC.
Fig. 7 Diagram showing direction of open reduction of DRUJ from volar approach.
Fig. 8
415
Torn DRUJ capsule was repaired by bone anchor sutures.
capsule was avulsed from the distal radius and there was a partial tear of the distal part of the pronator quadratus. Open reduction was performed and the capsule was repaired using 2 bone anchor sutures (Figs. 7 and 8). Stability was checked. Wrist arthroscopy was performed and found the TFCC to be intact both at the radial and ulnar side (sigmoid notch and fovea). Immobilisation by a hinge elbow brace with the forearm in neutral position for three weeks, followed by rehabilitation, was carried out after successful reduction. The patient subsequently enjoyed pain-free full range of motion (Figs. 9 and 10).
Fig. 9
Lateral view radiograph showing reduced DRUJ after operation.
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Fig. 10 Posteroanterior view radiograph showing reduced DRUJ after operation.
DISCUSSION Although terms such as volar or dorsal dislocation of the ulna at DRUJ are commonly used, it is important to be aware that the dislocation is actually caused by the displacement of the movable radius instead of the fixed ulna.5 As a result, volar DRUJ dislocation means that the ulna is in volar position with DRUJ dislocation, while dorsal DRUJ dislocation represents the dorsal position of the ulna. Volar DRUJ dislocations are commonly misdiagnosed, as many as 50% of cases,4 due to various reasons. Firstly, pronation and supination movements of forearm are not always examined, while the often tested flexion and extension movements of wrist are usually preserved. Secondly, local swelling at the wrist makes the usually ulnar prominence landmark ill-defined. Thirdly, the absence of fracture in radiographs gives a false reassurance that the wrist injury is minor. Isolated volar dislocation of DRUJ was first described by Cotton6 in 1912. In volar DRUJ dislocation, there is a history of hypersupination and the patients are unable to pronate their forearms.7–9 Another mechanism for volar DRUJ dislocation is a volarly applied force to the radius with a fixed ulna.6 On the other hand, in dorsal DRUJ dislocation, there is a history of hyperpronation, for example, a fall on the outstretched hand (hand is fixed by gravity to ground, but body with ulna rotates around the radius). In these injuries, patients are unable to supinate their forearms.7–9
Clinically, DRUJ stability is assessed by antero-posterior translation of the ulna on the radius in neutral, pronation and supination, with comparison to the contralateral side. With DRUJ dislocation, pronation or supination of forearm will usually be painful and limited.10 Morrissy recommended that both wrists should be inspected with the elbow in 90 degree flexion and forearm in neutral position.10 A dorsal prominence of the ulnar head should lead to the suspicion of dorsal DRUJ dislocation, while the presence of a hollow dorsally (at the usual site of ulnar head) points to volar DRUJ dislocation. In volar DRUJ dislocation, there is usually no ‘volar’ prominence of ulnar head due to the soft tissue bulk at the volar aspect of the wrist. However, the wrist looks narrower due to the compressive pull of pronator quadratus.11 Diagnosis should be confirmed by standardised radiographs. In the anteroposterior view, the patient’s hand is placed on the cassette with 90 degrees elbow flexion and shoulder abduction. The distal radioulnar joint is normally a 2–3 mm space in the wrist. As discussed above, the wrist will be narrower due to the pull of pronator quadratus in volar DRUJ dislocation, so there will be an overlap of the distal radius and ulna in anteroposterior radiographs of the wrist. The lateral radiographs should be taken by placing the patient’s ulnar forearm in neutral rotation on the cassette, with the elbow in 90 degrees flexion. Normally, the base of the third metacarpal, capitate, lunate and radius should be collinear, and the distal radius is superimposed on the ulna. In volar DRUJ dislocation, the distal ulna is displaced to the volar side.12,13 Regarding the choice of investigations for DRUJ, Mino12 carried out a prospective study that concluded with the following indications: in the absence of a deformity of the distal end of the radius, a lateral radiograph made with the wrist in the neutral position accurately revealed incongruency of the DRUJ joint. When pain or cast immobilization prevented optimum positioning of the wrist for radiography, or when a deformity of the distal end of the radius was present, computerised tomography (CT scan) gave a more accurate determination of the congruency of the joint. Stress radiographs included clenched-fist PA view in forearm pronation to assess DRUJ gap14 and weighted lateral stress view in pronation to assess instability.15 The CT scan performed in our patient was not for the diagnosis of the dislocation but for pre-operative planning of the reduction. Reduction of volar DRUJ dislocations require forcible pronation of the forearm with dorsally directed pressure on the
September 30, 2014
10:24:28am
WSPC/135-HS
FA1
1472027
Hand Surg. 2014.19:413-417. Downloaded from www.worldscientific.com by CHINESE UNIVERSITY OF HONG KONG on 02/13/15. For personal use only.
Locked Volar Distal Radio-Ulnar Joint Dislocation with Isolated Volar Capsule Rupture
ulnar head under sedation or anesthesia. Open reductions after failed closed reduction had been previously described,16 the incidence of this is much higher for volar dislocations compared the dorsal ones. This may be due to pull of pronator quadratus in acute cases, contracted volar soft tissues in late cases, or interposition of torn dorsal radioulnar ligament.17 Garrugues18 previously described an irreducible volar DRUJ dislocation with distal ulna blocked by the volar lip of sigmoid notch of radius and TFCC tear. In our patient, the ulna was also blocked by the volar lip of sigmoid notch with only isolated volar capsule tear. This combination has not yet been described in the literature. Since TFCC is the major stabilizer of DRUJ, DRUJ dislocation is associated with high incidence of TFCC injury, especially in patients with failed closed reduction. Yet this did not happen in this patient. We postulated that this might be contributed by the partial tear of the pronator quadratus. As our patient was going to undergo open reduction for the DRUJ dislocation, wrist arthroscopy (the gold standard for diagnosing TFCC injury) was arranged in the same session, so that repair could be done if there was any injury to the TFCC. The DRUJ can be approached by a volar approach or dorsal approach. In the volar approach, the incision is just radial to flexor carpi ulnaris tendon. In a series of 51 patients, there were no significant complications reported.19 A volar approach was used in this case because the dislocation was in the volar side and TFCC repair could be done in case there had been a tear. Arthroscopy was carried out in the same session to look for TFCC tear in view of the high-energy mechanism of injury. In contrast, when the incision is made in line with the fifth extensor compartment in the dorsal approach, the dorsal sensory branch of ulnar nerve may be injured.20 In conclusion, DRUJ dislocation remains a commonly missed injury and a high index of suspicion is recommended. A full examination of wrist range of motion including pronation and supination, detailed search for DRUJ injuries in radiographs despite the absence of fractures, and addressing the underlying problem causing the irreducible DRUJ dislocation all constitute a better management of this entity.
References 1. Hagert E, Hagert CG, Understanding stability of the distal radioulnar joint through an understanding of its anatomy, Hand Clin 26(4):459– 466, 2010.
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