39M presents with right wrist pain
39M with no PMH presents with right wrist pain. The day prior to presentation the patient was shoveling snow when he slipped and fell onto his outstretched right hand/wrist. The patient presented to an OSH in upstate NY where he had an x ray and was told he had a distal radius fracture. He was reduced, placed in a volar splint and discharged with instructions to follow up with a specialist. The patient presents today with worsening R wrist pain and numbness in his 4th and 5th digits.
- volar splint present
- prominence palpated on distal right ulnar aspect of wrist which is tender to palpation
- sensation diminished in 4th and 5th digits in an ulnar distribution
- unable to cross his fingers, unable to abduct 5th digit
- WWP, 2+ radial pulse
- 5/5 motor and sensation intact in radial and median nerve distributions
What does the x-ray show?
The x-ray shows:
- volar lunate dislocation with greater than 90 degrees of rotation and ulnar displacement
- comminuted mildly depressed intra-articular radial styloid fracture
- probable triquetral fracture
Explain the reason for the patient's neuro exam.
The patient's neuro exam (inability to cross his fingers and inability to abduct his 5th digit, decreased sensation in ulnar distribution of 4th and 5th digits) is explained by the patient's lunate dislocation which is causing an ulnar neuropathy. The lunate bone is displaced so far to the ulnar aspect of the hand that it is causing weakness in his intrinsic muscles and ulnar sensory deficits.
Explain your next step in management.
The next step in management is emergent closed reduction should be attempted especially given the patient's neuropathy, followed by open reduction, and ligament repair
Our Case: Orthopedics attempted closed reduction using fentanyl, propofol and a C-arm. Although the patient’s neuropathy was improved after this, the patient went to the OR for definitive repair.
- lunate dislocations occur when high energy injuries cause the wrist to extend and ulnarly deviate, this causes intercarpal supination
- as in our case, these injuries are commonly missed on initial presentation (25%)
- median nerve symptoms occur in 25% of patients, most commonly in Mayfield stage IV injuries where the lunate rotates and dislocates volarly into the carpal tunnel
- definitive non-operative repair universally results in poor functional outcomes and recurrent dislocation is common, these patients need operative repair. however emergent closed reduction does lead to reduction in nerve and cartilage damage (as was performed in our patient)
- acute injuries (<8 wks) require emergent open reduction and ligament repair. More chronic injuries may require a proximal row carpectomy or total wrist arthrodesis