Lunate dislocation, median nerve neurapraxia after low-energy mechanism
Click Here to Manage Email Alerts
A healthy 22-year-old right hand-dominant woman sustained an isolated, right lunate dislocation and ulnar styloid fracture after a fall while bicycling at an approximate speed of 5 miles per hour (Figure 1).
Sensory and motor deficits in the median nerve distribution distal to the wrist were reported at the time of initial presentation to an outside medical center where two attempts at closed reduction were unsuccessful. She was subsequently placed into a sugar-tong splint and transferred to our tertiary medical center.
Source: Alexander Lauder, MD
Clinical exam upon presentation was significant for right hand dysesthesias in the median nerve distribution and thenar muscle weakness with a notable inability to fully abduct and oppose her thumb. Two-point discrimination in the median nerve distribution of the hand was absent. Light touch and two-point discrimination remained intact to her small finger and the ulnar aspect of her ring finger. Closed reduction was successful in the ED and she was re-placed into a well-molded sugar-tong splint (Figure 2). The patient’s pre-reduction sensory and motor deficits of the median nerve remained unchanged following successful closed reduction.
What are the treatment options?
See answer below.
Urgent surgical intervention due to persistent median nerve deficits
Urgent surgical intervention is indicated for a perilunate or lunate dislocation with persistent median nerve deficits despite successful closed reduction.
Closed reduction is often the first-line treatment for perilunate and lunate dislocations. Closed reduction requires adequate sedation, pain control and recreation of the deformity classically described as wrist extension, ulnar deviation and intercarpal supination. A thorough neurologic examination, with particular attention paid to median nerve function distal to the wrist, is required before and after reduction.
The Mayfield grading system describes perilunate injuries on a scale of one to four that increases with the severity of carpal instability. Surgical intervention is the gold-standard definitive management for Mayfield grade 4 injuries (lunate dislocations), with or without successful closed reduction. Operative intervention includes open reduction and internal fixation of the lunate, as well as repair of intrinsic and extrinsic ligaments, when indicated, with the primary goal of restoring carpal stability.
Extended carpal tunnel release
A volar incision was made in line with the radial aspect of the fourth ray, proximal to Kaplan’s cardinal line, and extended 3 cm proximal to the wrist crease using an ulnar-directed Bruner’s incision to protect the palmar cutaneous branch of the median nerve (PCBMN). Release of the transverse carpal ligament revealed a large hematoma within the carpal tunnel. The median nerve was intact with multiple, 1-cm areas of epineural hemorrhage. Careful dissection of the nerve was carried out proximally and distally to visualize the PCBMN and the recurrent motor branch, respectively. Gentle retraction of the carpal tunnel contents ulnarly and radially revealed significant disruption of the extrinsic volar ligaments, particularly the radioscaphocapitate ligament and the ulnocarpal ligaments, respectively (Figures 3 and 4). The lunate freely subluxed volarly with ulnar deviation and extension of the hand. Ligamentous repair with 2-0 Vicryl in a horizontal mattress fashion was favored over suture-anchor repair as injury occurred mid-substance rather than as an avulsion at the carpal insertion. The lunate maintained its normal articulations during manipulation of the hand following this volar extrinsic ligament repair.
Lunate reduction, internal fixation
A dorsal approach to the wrist was performed. The dorsal radiocarpal ligament and capsule were found to be avulsed from the dorsal radial styloid. Kirschner wires used as joysticks were placed into the body of the lunate and scaphoid to reduce the extension and flexion deformities, respectively. Carpal alignment and restoration of Gilula’s line were ensured under direct visualization and fluoroscopy. Carpal fixation was carried out percutaneously with 4.5-mm Kirschner wires (Figure 5), taking care to avoid iatrogenic injury to branches of the superficial radial nerve and dorsal cutaneous branch of the ulnar nerve.
Ligamentous repair
The injury to the scapholunate (SL) ligament was complex, including a nearly complete midsubstance disruption as well as complete avulsion from the proximal scaphoid. The lunotriquetral ligament was disrupted at its mid-substance. Avulsion of the SL ligament and dorsal radiocarpal ligament were repaired with a 4.75-mm SwiveLock suture anchor (Arthrex) and the SL ligament substance tear was repaired with Vicryl suture. The carpus and distal radioulnar joint were found to have excellent stability after fixation. The patient was placed into a long arm splint for 2 weeks with a plan to transition to a short arm cast until pin removal tentatively at 3 months. Her nerve examination immediately postoperatively was unchanged.
Discussion
Perilunate dislocations and fracture dislocations are uncommon, typically high-energy injuries that are traditionally the result of wrist extension, ulnar deviation and intercarpal supination. The rate of median neuropathy after these injuries has been reported between 24% and 45%. The exact rate of high-grade perilunate dislocations or fracture dislocations is difficult to determine due in part to diagnostic coding limitations and because these injuries may be missed in the acute setting. This case report describes a typically high-energy injury seen in a young, healthy woman with no previous wrist trauma after a low-energy mechanism.
Timing of surgical intervention is contingent upon the success of closed reduction and presence of compressive neuropathy. Emergent surgical intervention is indicated when closed reduction is unsuccessful and/or there is a concern for acute carpal tunnel syndrome. There is debate about the surgical approach (volar, dorsal or combined) for high-grade perilunate dislocations. Advocates of the dorsal-only approach argue that volar ligament opposition occurs following carpal fixation and immobilization, and a combined volar approach may not justify the added risk of swelling and dysvascularity. However, it is agreed that the combined volar-dorsal approach is indicated in the setting of associated acute carpal tunnel syndrome. The patient’s median nerve deficits resolved spontaneously by 3 months from the date of injury, representing a neurapraxic injury most likely the result of the initial energy/dislocation and perhaps accentuated by the sizable carpal tunnel hematoma appreciated at the time of surgery.
It is critical that long-term outcomes are appropriately discussed with the patient near the time of injury. Common complications include post-traumatic arthrosis, permanent wrist stiffness, transient lunate ischemia, loss of function, instability and complex regional pain syndrome. Return to preinjury range of motion and grip strength should not be the expectation, however, functionally, a return to sport or work is common. Sixteen of 22 patients (73%) after fixation of a perilunate dislocation using a combined volar-dorsal approach returned to full duties in their previous occupation by an average final follow-up of 3 years. Outcomes are improved with early intervention and surgical repair/reconstruction, and pain is generally mild to moderate and activity dependent at medium- and long-term follow-up despite a high rate of post-traumatic arthritis.
The patient was discharged from the hospital the day of surgery and returned home (out of state) where follow-up was arranged. She was contacted by our group 3 months after surgery at which time her sensation had returned to baseline. She denied any postoperative complications, including pin site infection, and she had been working with physical therapy twice a week to advance her wrist range of motion. She was satisfied with her care and the prognostic discussion that took place at the time of presentation. With regard to patients suffering from a similar injury, she would like to stress the importance of perseverance during the rehabilitation period and the value of a strong social/familial support system.
Herein, a unique case of a low-energy lunate dislocation was described that required emergent surgical intervention for persistent, acute carpal tunnel syndrome after successful lunate reduction.
- References:
- Frane N, Goldenberg W. Perilunate dislocation. StatPearls [Internet]. [Updated 2021 August 24]. Treasure Island, FL: StatPearls Publishing; 2021. www.ncbi.nlm.nih.gov/books/NBK557709/. Accessed Jan. 11, 2022.
- Herzberg G, et al. J Hand Surg Am. 1993;doi:10.1016/0363-5023(93)90041-Z.
- Herzberg G, et al. J Hand Surg Br. 2002;doi:10.1054/jhsb.2002.0774
- Herzberg G. Tech Hand Up Extrem Surg. 2000;doi:10.1097/00130911-200003000-00002.
- Hildebrand KA, et al. J Hand Surg Am. 2000;doi:10.1053/jhsu.2000.17868.
- Knoll VD, et al. J Hand Surg Am. 2005;doi:10.1016/jhsa.2005.07.007.
- Mayfield JK. Clin Orthop Relat Res. 1980;(149):45-54.
- Papadonikolakis A, et al. J Bone Joint Surg Am. 2003;doi:10.2106/00004623-200309000-00023.
- White RE Jr, et al. J Hand Surg Am. 1984;doi:10.1016/S0363-5023(84)80137-9.
- For more information:
- Thomas France, MD, can be reached at the University of Colorado, Department of Orthopedic Surgery, 12631 E. 17th Ave., Mail Stop B202, Aurora, CO 80045; email: thomas.france@cuanschutz.edu.
- Alexander Lauder, MD, can be reached at Denver Health, Department of Orthopaedic Surgery, 777 Bannock St., Denver, CO 80204; email: alexander.lauder@dhha.org.
- W. Charles Lockwood, MD, can be reached at the University of Colorado, Department of Orthopedic Surgery, 12631 E. 17th Ave., Mail Stop B202, Aurora, CO 80045; email: winthrop.lockwood@cuanschutz.edu.
- Edited by Steven D. Jones Jr., MD, and Donald (DJ) Scholten, MD, PhD. Jones is a chief resident in the department of orthopedic surgery at the University of Colorado. He will pursue a fellowship in sports medicine at Stanford University following residency completion. Scholten is a chief resident in the department of orthopedic surgery at Wake Forest University School of Medicine in Winston-Salem, North Carolina. He will be a sports medicine fellow at the University of Michigan following residency. For information on submitting Orthopedics Today Grand Rounds cases, please email: orthopedics@healio.com.
Collapse
Click Here to Manage Email Alerts