Common Carpal Injuries - Identification and Early Management

Tod Clark, M.D., FRCSC
Winnipeg, MB

Stephen Kennedy, M.D., FRCSC
Seattle, WA

Introduction
Wrist movement occurs through the complex, yet balanced, movement of carpal bones and their capsuloligamentous attachments. When disrupted, instability, pain, articular shear, and arthrosis may result, and such injuries may occur more often than we realize1. Many of these injuries are missed in the acute setting. Seven percent of distal radius fractures have an associated carpal fracture, 18-64% have a scapholunate ligament tear, and 12-16% have a lunotriquetral ligament tear2-6. Accurate diagnosis and early treatment lead to the most favorable outcomes1,7. The purpose of this COA Bulletin Themes section is to review the evaluation and treatment of acute carpal injuries. The most common injuries will be reviewed while diagnostic and treatment pearls will be offered to minimize both misdiagnosis and delayed treatment.

 

Diagnosis and Radiographic Interpretation
Plain film radiographs of the wrist are indispensable. These should be taken in the absence of plaster when possible. Views should include posteroanterior (PA), true lateral, scaphoid/ulnar deviation, and occasionally clenched fist. The true lateral view is taken in line with the lunate facet of the radius, at about ten degrees of inclination. An adequate lateral view superimposes the scaphoid tubercle on the pisiform, and the radius and ulna are superimposed proximally (Figure 1). The scaphoid view is taken with the wrist in ulnar deviation and with angulation of the tube by approximately 20 degrees, which gives an apparent elongation to the scaphoid helping in the identification of subtle fractures.

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Figure 1. PA (Sl interval and Gilula’s lines) and lateral views (lunate, capitate and scaphoid outlined)

If a scaphoid fracture is identified, careful note is made of the location of the fracture, translation, angulation, and comminution. Care should also be taken to look for any signs that the injury is not acute (i.e. rounded or sclerotic edges, cystic changes, proximal pole radiodensity). These factors will play a major role in determining management. Distance between the scaphoid and lunate of 1-2 mm on the PA view is normal8. Scapholunate widening or a gap of greater than 2.5 mm is indicative of scapholunate ligament tear8. This has historically been referred to as the "Terry Thomas Sign," referencing a large gap between the comedian's front teeth.

Disruption of the intrinsic proximal row ligaments (SL and LT) leads to carpal instability and later arthritis. Simply put, the scaphoid tends to flex and the triquetrum tends to extend. Displaced scaphoid waist fractures may have distal pole flexion relative to the proximal pole, causing the classic "humpback deformity." The lunate passively follows its remaining carpal attachments. In most cases, when the scaphoid or scapholunate ligament is disrupted, the lunate remains attached to the triquetrum and tends to tilt into extension. This is known as dorsal intercalated segment instability or DISI. On the lateral view this is shown by a radiolunate angle greater than 13 degrees or a scapholunate angle greater than 63 degrees (Figure 2)8. A "signet ring" sign may be observed on the PA view because scaphoid flexion causes the tuberosity to be superimposed on the round waist. In lunotriquetral disruption, the lunate follows the scaphoid into flexion. This is volar intercalated segment instability or VISI.

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Figure 2. SL angle (normal is 30º-60º)

 

Gilula's lines are a sensitive tool for the identification of carpal disruption (Figure 1). These lines follow the articular surfaces of the proximal carpal row (at the radiocarpal and midcarpal joints) and the proximal articular surface of the distal carpal row. Without injury these should be smooth and concentric. In cases that are not clear, traction imaging may be a useful adjunct as this increases disruptions of Gilula's lines, but remains somewhat subjective8. On the lateral image carpal disruption should be assessed by ensuring the lunate facet, lunate and capitate are all collinear, known as the 3C's (Figure 1). Alternatively, CT scan or MRI can identify minimally displaced carpal fractures with high sensitivity8. If dislocated, closed reduction should be attempted first, and if the wrist is reduced and splinted, advanced imaging can be performed in the following days. Wrist arthroscopy remains the gold standard diagnostic tool, and may be considered prior to open management8.

In the next three sections, the authors contributing to this COA Bulletin feature will elaborate further on key issues in management of acute scaphoid fracture, acute scapholunate ligament tears, and perilunate dislocations.

References

  1. Herzberg G., Comtet J.J., Linscheid R.L., et al. Perilunate dislocations and fracture-dislocations: a multicenter study. J Hand Surg Am. 1993;18:768-779.
  2. Komura, S., Yokoi, T., Nonomura, H., Tanahashi, H., Satake, T., & Watanabe, N. (2012). Incidence and characteristics of carpal fractures occurring concurrently with distal radius fractures. The Journal of Hand Surgery, 37(3), 469-476. doi:10.1016/j.jhsa.2011.11.011
  3. Forward D.P., Lindau T.R., Melsom D.S. Intercarpal Ligament Injuries Associated with Fractures of the Distal Part of the Radius. J Bone Joint Surg Am. 2007;89(11):2334-2340.
  4. Richards R.S., Bennett J.D., Roth J.H., et al. Arthroscopic diagnosis of intra-articular soft tissue injuries associated with distal radial fractures. J Hand Surg Am. 1997;22(5):772-776.
  5. Lindau T., Arner M., Hagberg L. Intraarticular lesions in distal fractures of the radius in young adults. A descriptive arthroscopic study in 50 patients. J Hand Surg Br. 1997;22(5):638-643.
  6. Geissler W.B., Freeland A.E., Savoie F.H., McIntyre L.W., Whipple T.L. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg Am. 1996;78(3):357-365.
  7. Zarkadas P.C., Gropper PT, White NJ, et al. A survey of the surgical management of acute and chronic scapholunate instability. J Hand Surg Am. 2004;29(5):848-857.
  8. Megerle, K., Pöhlmann, S., Kloeters, O., Germann, G., & Sauerbier, M. (2011). The significance of conventional radiographic parameters in the diagnosis of scapholunate ligament lesions. European Radiology, 21(1), 176-181.

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