case report wrist dislocation cover

Case Report: Complete Radiocarpal Dislocation

Case Introduction

A 32 year old male presents to the emergency department (ED) via ambulance after an approximately 80 mph helmeted motorcycle crash (MCC). His chief complaint is pain in his left arm and left shoulder. After evaluating for other injuries, you identify a left wrist deformity with exposed bone. His sensorimotor exam is notable for reduced sensation along the left 5th digit. Subsequent radiographs identify trans-scaphoid perilunate dislocation, with resulting complete radiocarpal dislocation. 

Wrist XR Complete Radiocarpal Dislocation.

Figure 1. Initial radiograph showing complete radiocarpal dislocation.

Wrist XR Complete Radiocarpal Dislocation SP reduction

Figure 2. Posterior-anterior radiograph immediately following reduction and splinting in the trauma bay.

Procedure: Perilunate and Wrist Dislocation Reduction

All perilunate dislocations must be reduced in the ED as soon as possible. This must be done to reverse median nerve compression at the carpal tunnel, as well as to decompress the vasculature supplying the displaced carpal bones.[1]Stanbury SJ, Elfar JC. Perilunate dislocation and perilunate fracture-dislocation. J Am Acad Orthop Surg. 2011 Sep;19(9):554-62. doi: 10.5435/00124635-201109000-00006. PMID: 21885701. After appropriate analgesia and/or anesthesia, the operator should apply uninterrupted finger trap traction with the patient’s elbow flexed 90° for 10-15 minutes.
Once the muscles of the hand are fatigued, the following methodology of closed reduction can be performed. While maintaining longitudinal traction during the entire procedure, the patient’s wrist is extended using one hand, while the thumb of the other hand stabilizes the lunate by pushing dorsally on the palmar surface of the wrist. Gradual wrist flexion allows the capitate to relocate into the concavity of the lunate. Once the lunocapitate joint is reduced, the wrist is gradually reextended while applying dorsal pressure on the lunate.[2]Budoff, Jeffrey E. “Treatment of acute lunate and perilunate dislocations.” The Journal of hand surgery 33.8 (2008): 1424-1432.[3]Blazar PE, Murray P. Treatment of perilunate dislocations by combined dorsal and palmar approaches. Tech Hand Up Extrem Surg 2001;5:2–7.
As this patient also had complete radiocarpal dissociation, a radially directed force was applied to the distal ulna, and an ulnar force was applied to the carpals. The wrist should then be immediately splinted with a sugar tong. The proceduralist should take care to carefully mold this splint against the highly unstable joint.

Intracarpal Injuries

Intracarpal injuries such as perilunate dislocation and trans-scaphoid fracture-dislocation are rare orthopedic traumatic injuries mainly seen in youths with high-energy trauma to the wrist. Perilunate dislocations occur when the lunate remains located in its fossa, but the remainder of the carpus is dorsally dislocated. In trans-scaphoid injury patterns, the proximal pole of the scaphoid travels with the lunate and may also be dislocated into the carpal tunnel, leading to median nerve dysfunction. While these are rare injuries overall, perilunate dislocations are the most common type of carpal dislocation, and account for roughly 10% of all carpal injuries.
wrist xray arc of gilulaa or gilula's arcs

Figure 3. Radiograph showing Gilula’s arcs. Three smooth arcs normally outline proximal (arc I) and distal (arc II) cortical margins of the proximal carpal row and proximal carpal surfaces (arc III) of the hamate and capitate are shown in a posteroanterior view of the wrist.[4]Vezeridis, Peter S., et al. “Ulnar-sided wrist pain. Part I: anatomy and physical examination.” Skeletal radiology 39 (2010): 733-745.

wrist xray piece of pie sign lunate dislocation 2

Figure 4. AP wrist showing lunate (blue markings) has taken on a triangulare appearance, the so-called ‘slice of pie’ sign, consistent with lunate dislocation.[5]Case courtesy of Andrew Dixon, Radiopaedia.org, rID: 9906

lunate dislocation spilled teacup sign xray

Figure 5. Lateral radiograph shows the “spilled teacup sign” as seen in lunate dislocation. White markings represent expected points of articulation.[6]Peña, Jonathan. “Lunate Dislocation.” Journal of Education and Teaching in Emergency Medicine 2.1 (2017).

Gilula’s lines: there are 3 arcs which should be evaluated on an AP view of the wrist to assess the alignment of carpal bones. A disrupted arc may indicate a ligamentous injury, or fracture where these virtual lines are disrupted.

      1. First arc: this runs along the proximal convexity of the scaphoid, lunate, and triquetrum.
      2. Second arc: this runs along the distal concavities of the scaphoid, lunate, and triquetrum.
      3. Third arc: this runs along the proximal curvatures of the capitate and hamate.

These dislocations may be missed in 25% of cases, which is problematic as nonsurgical management of transscaphoid perilunate injuries universally results in poor outcomes, including arthritis, reduced strength, or regional pain syndromes.[7]Herzberg G, Comtet JJ, Linscheid RL, Amadio PC, Cooney WP, Stalder J. Perilunate dislocations and fracture-dislocations: a multicenter study. J Hand Surg Am. 1993;18(5):768–79.
 Recognising the classical radiographic signs including disruption of Gilula’s arcs, “slice of pie” and “spilled teacup” signs on AP and lateral radiographs respectively , and overlapping of the carpal bones is imperative in cases where dislocations may otherwise be missed.

trans scaphoid perilunate dislocation wrist xray

Figure 6. The capitate (blue) is dorsally dislocated relative to the lunate (yellow). The lunate is articulating with the radius, hence this is a perilunate dislocation.[8]Case courtesy of Andrew Dixon, Radiopaedia.org, rID: 9893

perilunate dislocation xrays

Figure 7. Further radiograph images identifying a perilunate dislocation.[9]Image courtesy of http://www.svuhradiology.ie/case-study/perilunate-dislocation/

Regarding the mechanism of injury, experimental work by Mayfeild demonstrated one pattern of force transduction, in hyperextension of the wrist leads to intercarpal supination, and a cascade of transmitted forces. The initial force is sent through the scaphoid, and/or, through the scapholunate interval which can cause scapholunate and radioscaphocapitate ligament tears. Thereafter, the capitolunate articulation is disrupted, followed by lunotriquetral disruption.[10]Muppavarapu RC, Capo JT. Perilunate Dislocations and Fracture Dislocations. Hand Clin. 2015 Aug;31(3):399-408. doi: 10.1016/j.hcl.2015.04.002. PMID: 26205701.[11]Obert L, Loisel F, Jardin E, Gasse N, Lepage D. High-energy injuries of the wrist. Orthop Traumatol Surg Res. 2016;102(1 Suppl):S81–93. Conversely, Lauland proposed that intracarpal pronation following injury to the ulnar side of the carpus, with a hypothenar impact and fracture of the associated pisiform, leads to perilunate dislocations. The literature would support that the majority of perilunate dislocations actually result from this second mechanism.[12]Laulan J.: Désaxation scapholunaire : physiopathologie et orientations thérapeutiques. Chir Main 2009; 28: pp. 192-206
More specifically, during ulnar extension and inclination, the lunate bone is situated snugly beneath the joint surface of the radius. The triquetrum and hamate are also neatly alignmed with each other in this position. Because of this, an injury to the hypothenar region initially stresses the triquetrolunate area, leading to a possible separation between the lunate and triquetrum bones (stage 1). The triquetrum bone pushes the hamate bone backward, but as the lunate bone is still shielded by the posterior edge of the radius, the next point of force dispersion occurs between the lunate and capitate bones.
In this case (stage 2), the capitate bone may dislocate backward, while the scaphoid bone remains locked in its proper position by the radius. This stage presents a higher risk of misdiagnosis, as demonstrated by cases reported by Sochard and Birdsall. If the force causing the injury persists, the scaphoid bone contacts the posterior edge of the radius, which can result in a fracture of the scaphoid bone, a fracture of the radial styloid, or both (stage 3).

Other Intracarpal Injuries

There are other, rarer patterns of injury that could be missed by plain films alone. Fenton syndrome, or Scaphocapitate syndrome, is a particular form of perilunate dislocation in which the scaphoid and the capitate are fractured, with 90 to 180 degree rotation of the head of the capitate. This injury ranges from the classic Fenton syndrome (dorsal perilunate dislocation associated with an atypical fracture of the scaphoid and a fracture of the capitate head), to fractures of all the bones of the proximal or distal row. In dubious cases, a CT scan may be helpful in establishing this diagnosis.[13]Vance RM, Gelberman RH, Evans EF (1980) Scaphocapitate fractures. Patterns of dislocation, mechanisms of injury, and preliminary results of treatment. J Bone Joint Surg Am 62:271–276 These are also treated with ORIF.

Distal Radius Fractures

These injuries include a combination of metaphyseal and epiphyseal lesions, which can be associated with ligamentous injury at the radiocarpal, mediocarpal, or distal radioulnar level. These occur secondary to wrist hyperextension and variable pronation-supination. The greater the trauma energy, the more there will be metaphyseal injuries, then epiphyseal injuries, and then dislocations. Contusion of the median nerve is classic but can go unnoticed secondary to distraction, which makes the prognosis more severe. These frequently require surgical fixation, but the timing of such depends on the specific location and degree of comminution of the fractures. Prior to surgery, a CT of the distal radius/wrist should be considered for planning purposes.
Wrist XR 2 months after surgery

Figure 8. Two months following surgery. Interval surgical resection of proximal carpal row with a few residual osseous fragments.

Case Conclusion

This patient underwent a successful closed reduction of the radiocarpal dislocation in the emergency department after procedural sedation, and was admitted to orthopedic surgery for surgical exploration the following day. In the operating room, the patient was found to have a transection of his ulnar nerve and artery, as well as complete disruption of the radioscaphocapitate ligament. Surgical interventions included ulnar nerve and artery repair, proximal row carpectomy secondary to denuded lunate, carpal tunnel release, and radioscapholunate ligament repair after debridement and irrigation of the wound. He was seen as an outpatient in the orthopedic surgery clinic with good adherence to hand therapy, and continues to make excellent progress with ROM and return to ADLs.

Author

Ian Benjamin, MD, PGY2

University of Washington Emergency Medicine Residency Program

– More Wrist Pain: https://www.sportsmedreview.com/by-joint/wrist/

– Wrist Pain @ Wiki Sports Medicine: https://wikism.org/Wrist_Pain_Main

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