Discussion

Wrist injuries after a fall on an outstretched hand (FOOSH) are common in any age group. However, SL ligament tears are more common in adults, especially adult athletes. A myriad of diagnoses are associated with wrist injuries, including sprains, strains, and fractures (single or multiple) of the distal radius, ulna, or any of the carpal bones (with the most common being scaphoid). The most important diagnostic tool is the initial history and physical exam. Acute injuries, if appropriately diagnosed, are easier to treat and result in lower morbidity and subsequent unwanted sequelae.1,2

Patients whose radiographs are read as negative are often thought to have wrist sprains and/or strains. These patients are usually treated conservatively with splints for several weeks to months. If pain persists following immobilization, it may be due to a ligament tear (either partial or complete), which can cause continued pain and/or decreased motion (especially rotation).1-4

Typical acute symptoms of a scapholunate tear are wrist pain in the dorsolateral aspect of the wrist (1 cm distal to the dorsoradial tubercle), swelling and/or bruising, weak hand grip, and loss of wrist motion. There may also be a popping or clicking sound with motion.5 Watson’s maneuver (scaphoid shift test) is a physical exam to assess for SL laxity. The examiner places his or her thumb on the distal aspect of the scaphoid, using the opposite hand to axially load the wrist. The wrist would be passively brought from ulnar to radial deviation. If the test is positive, the pressure exerted dorsally will result in dorsal wrist pain and often a palpable “clunk.” Exam of the contralateral wrist may help differentiate laxity from normal motion.2,5

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Initial radiographs consist of a posterior-anterior (PA) wrist film, lateral wrist film, and often an oblique wrist film and/or a scaphoid view (wrist in ulnar deviation looking for an acute scaphoid fracture). With a scapholunate injury, a ≥5-mm space is noted between the scaphoid and lunate bones on the PA view or a >2- to 3-mm difference from the contralateral side. This is also known as the “Terry Thomas” sign after a British actor who had a gap between his teeth.3,5 If the radiograph is unremarkable but the history and physical exam are indicative of an SL tear, stress radiographs are warranted.  These are completed with a patient clenching his or her fist, then supinating and ulnarly deviating the wrist, which may reveal dynamic SL widening.5

Advanced imaging may consist of an MRI with or without arthrography or a CT scan. A CT scan is more helpful in diagnosing carpal/radial fractures, while an MRI can best assess soft tissue injuries. Some clinicians prefer wrist arthroscopy for diagnosis and treatment, but ongoing research is being conducted in this area.2,5

Misdiagnosis of an SL tear may result in carpal or radiocarpal avascular necrosis, osteoarthritis, decreased wrist function, and/or continuous pain. Scapholunate advanced collapse (SLAC) is an advanced arthritis due to progressive instability and results in significant morbidity. When surgical intervention is based on reconstruction rather than initial repair, outcomes are not as optimal for the patient.2,5,6 Office visits for wrist injuries may not always be benign. It is crucial to conduct a careful history and complete physical examination with subsequent radiographs as deemed necessary, especially when there is no fracture associated with the injury and the patient has significant wrist pain. When in doubt, a timely referral to a hand surgery specialist is necessary.

Pamela Horn, MS, CNP, RNFA, ONP-C, is the Orthopaedic Allied Health Professional Lead  and Matthew Beran, MD, is a faculty member of the Department of Orthopaedics at the Nationwide Children’s Hospital in Columbus, Ohio.

References

  1. Kulhawik D, Szalaj T, Grabowska, M. Avascular necrosis of the lunate bone (Kienbock’s disease) secondary to scapholunate ligament tear as a consequence of trauma—a case study. Pol J Radiol. 2014;79:24-26.
  2. Pappou I, Basel J, Deal D. Scapholunate ligament injuries: a review of current    concepts. Hand (N Y). 2013;8(2):146-156.
  3. Clark D, von Schroeder H. Scapholunate ligament injury: the natural history.  Can J Surg. 2004;47(4):298-299.
  4. Rohman EM, Agel J, Putman MD, Adams JE. Scapholunate interosseous ligament injuries: a retrospective review of treatment and outcomes in 82 wrists. J Hand Surg Am. 2014;39(10):2020-2026.
  5. Fufa D, Goldfarb C. Sports injuries of the wrist. Curr Rev Musculosketel Med. 2013;6(1):35-40.
  6. Vitale M. SLAC (Scaphoid lunate advanced collapse). Orthobullets. http://www.orthobullets.com/hand/6043/slac-scaphoid-lunate-advanced-collapse

Topics:

Hospital Medicine Orthopedics Surgery