Pak J Med Res Case Report Vol. 51, No. 3, 2012

Lunate Dislocation

Khaled Al Assiri, Javaid Iqbal, M Akhtar Khan Raja Department of Trauma & Orthopaedic Surgery, Armed Forces Hospital, Southern Region, Khamis Mushayt, Saudi Arabia.

Abstract

Carpal dislocations are wrist injuries and Lunate dislocation is its severe form. Lunate and perilunate dislocations are uncommon. These injuries have significant clinical impact on the patient but are easily missed and lead to potentially devastating effect if mismanaged. This case report outlines the important clinical aspects and management of Lunate dislocation. Key words: Lunate, dislocation.

Introduction an outstretched left hand. He complained of pain, swelling, trouble in moving his left wrist along with rist has a complex anatomy with multiple bones numbness of his left thumb, index and middle finger. His W and joints that lead to infinite combination of past medical history was insignificant and had no positions and movements. Although wrist fracture/ previous injuries to his left wrist. Examination of his left dislocation is a rare entity among all cases of extremity wrist revealed a moderate swelling, mainly over the volar trauma, but a number of specific injuries should be aspect with marked volar tenderness. All his left wrist looked for to rule out their presence. Lunate dislocation is movements were severely restricted and he was unable to such injury1. make a fist secondary to pain. There was paraesthesia in The morbidity of carpal dislocation is frequently the distribution of median nerve but there was no motor associated with missed diagnosis of lunate dislocation in deficit or circulatory compromise. the emergency department due to the complex structure Plain radiographs of left wrist (PA and lateral of the wrist. Unfortunately, missed injuries of the wrist views) showed dislocated lunate volarly while radius and are associated with a high incidence of long-term pain capitate remained in a straight line with a characteristic and disability2. “spilled tea cup sign” due to volar rotation. There was The true incidence of lunate dislocation is characteristic triangular appearance of lunate on PA view unknown, but the carpal dislocations are estimated to (normally a quadrangular appearance) known as “piece of account for 10% of all wrist injuries3. pie” sign due to rotation of lunate in volar direction Lunate dislocation results from hyperextension of the (Figure-1 & 2). A diagnosis of lunate dislocation was wrist due to high energy trauma to the wrist. This often made. It was differentiated from perilunate dislocation on results from fall on the outstretched hand, motor vehicle the lateral view where the whole carpus apart from lunate and motorcycle crash4. was dislocated while the lunate and radius remained in In lunate dislocation, there is disruption between articulation. On PA view it was differentiated from the lunate bone and the lunate fossa of the radius. This scapholunate dissociation where there was widening of requires emergent reduction and stabilization using either space between lunate and scaphoid. closed or open surgery with internal fixation. A lunate Closed reduction under general anesthesia was dislocation with median nerve symptomatology requires unsuccessful therefore, he was operated via volar immediate surgical reduction, carpal tunnel release and approach to gain access to lunate. Carpal tunnel release ligamentous reconstruction5 . was performed as part of volar approach to wrist and to decompress median nerve because of volar swelling and Case Report paraesthesia in the distribution of median nerve. Corresponding Author: A 45 years old male presented to the Accident & Khaled Al Assiri Emergency department of Armed Forces Hospital, Department of Trauma & Orthopaedic Surgery Southern Region, Khamis Mushayt, Kingdom of Saudi Armed Forces Hospital, Southern Region Arabia, with the complaints of left wrist pain. He was Khamis Mushayt, Saudi Arabia. involved in sports activities and had a history of fall on Email: [email protected]

Pakistan Journal of Medical Research, 2012 (July - September) 101 Khaled Al Assiri, Javaid Iqbal, M Akhtar Khan Raja

Hematoma in the space of Poirier was evacuated, and a After 2 weeks sutures were removed and check small osteochondral fracture of lunate was identified in x-ray done. Volar slab was re-applied for another 4 addition to complete dislocation of lunate. The weeks. At 6 weeks k-wire was removed (Figure-5) and osteochondral fragment was excised. After anatomical the patient was referred for physiotherapy to start gentle reduction the instability of wrist was identified under range of movement of his left wrist. image intensifier. Stability was achieved with the help of a trans-scapholunate 1.25 mm k-wire (Figure-3 & 4). After repair of volar arcuate ligament, tourniquet was deflated and hemostasis secured. After skin closure, wrist was immobilized in a short arm volar slab in neutral position. There was significant pain relief and improvement in paraesthesia on the 1st postoperative day.

Figure-5: At 6-weeks post removal of k-wire.

At 3 months postoperatively (Figure-6), the patient had regained the majority of his pain free motion and strength, and returned to normal activities. He was advised to avoid sports for another 3 months. His motion showed 65 degree of extension, 70 degree of flexion, 15 degree of radial deviation and 30 degree of ulnar deviation. His grip strength on the affected side was almost comparable to contralateral side. His functional outcome according to Wrist Mayo Score was 80% (Good).

Figure-1& 2: Pre-operative x-rays.

Discussion

Figure-6: X-rays at 3 months.

Lunate and Perilunate fracture dislocations typically occur in young people due to high-energy trauma. The mechanism of injury is an excessive loading force applied to a dorsiflexed and ulnarly deviated wrist 6. Mayfield classified carpal dislocations in to 4 stages, each representing a sequential intercarpal injury. A scapholunate disruption is stage-1 injury; stage-2 injury Figure-3 & 4: Immediate post-operative x-rays. involves dislocation of the lunocapitate joint. Stage-3

Pakistan Journal of Medical Research, 2012 (July - September) 102 Lunate Dislocation injury is the disruption of lunotriquentral joint and lunate References dislocation is classified as a stage 4 injury7. On the PA view of the wrist, three arcs should 1. Chin HW, Uehara DT. Wrist injuries. In Tintinalli JE, be identified. The first arc consists of the radiocarpal row; Kelen GD, Stapczynski JS, editors. emergency medicine. disruption of this indicates lunate dislocation. The second New york: McGraw-Hill; 2000. p.1772-83. arc consists of midcarpal row, disruption of indicates 2. Bednar JM, Osterman Al. Carpal instability: evaluation perilunate dislocation. The third arc outlines the proximal and treatment. J Am Acad Ortho Surg 1993;1:10-5. surface of the distal carpal row. On the lateral view of the 3. Larsen CF, Lauritsen J. Epidemiology of acute wrist trauma. Int J Epidemiol 1993;22: 911-6. wrist, the radius, lunate and capitate all lie in a row. Loss 8 4. Yeager BA, Dalinka MK. Radiology of trauma to the of this axis implies lunate or perilunate dislocation . wrist: Dislocations, fracture dislocations, and instability In one study two case of palmar lunate patterns. Skeletal Radiol 1985; 13:120-30. dislocations were treated with longitudinal volar 5. Andrew D, Perron MD, William J et al. orthopedic pitfalls approach and stabilized with k-wires. The satisfactory in ED: Lunate and perilunate injuries. Am J Emerg Med functional outcome having mayo wrist score of 75% was 2001; 19:157-62. achieved in these cases9. 6. Nirpama K, Usha S. Lunate and perilunate dislocations. Lunate and perilunate dislocations require Pediatr Emerg Care. 2010;26: 921-4. urgent identification and reduction to avoid a poor 7. Mayfield JK, Johnson RP, Kilcoyne RK. Carpal outcome. Closed reduction and immobilization is usually dislocations: Pathomechanics and progressive lunar instability. J Hand Surg Am. 1980;5:226-41. not successful but closed reduction with percutaneous 8. Herzberg G, Comtet JJ, Linscheid RL. Perilunate fixation are acceptable if reduction achieved with dislocations and fracture dislocations: a multicenter study. accuracy. Open reduction and fixation give the best J Hand Surg Am 1993;18:768-79. results in term of anatomical restoration10. 9. Isenberg J, Prokop A, Schellhammer F, Helling HJ. Palmar In summary, acute lunate dislocations are lunate dislocation. Unfallchirurg. 2002;105:1133-8. uncommon. When left unrecognized and untreated, can 10. Weil WM, Slade JF III, Trumble TE. Open and lead to a high incidence of long-term functional disability arthroscopic treatment of perilunate injuries. Clin Orthop and chronic wrist pain and to our knowledge there is Relat Res 2006;445:120-32. limited literature regarding isolated lunate dislocation to compare.

Pakistan Journal of Medical Research, 2012 (July - September) 103