Smith Fracture

28 yo male with wrist pain due to a fall • Xray of the Week What is the eponymous name of this fracture?

Figure 1: Type 1 Smith fracture: Volar displacement of distal fragment of radius fracture (blue arrow). Note that this is an extraarticular fracture.

Figure 2: Type 2 Smith fracture in a different patient: Volar and proximal displacement of distal fragment of radius fracture (blue arrow). Note that this is an intraarticular fracture (yellow arrow).

Figure 3: Mechanism of injury for Smith fracture. Diagram by Shama Jaswal.

Discussion:

A Smith fracture or a reverse Colles fracture is an extraarticular fracture of the distal radius with a volar displacement or angulation of the distal fragment (Figs. 1,2). It was named by Irish surgeon Robert William Smith in 1847, who incidentally followed Abraham Colles as Professor of Surgery at Trinity College in Dublin [1].

Smith fractures are rare, making up approximately 5% of all radial and ulnar fractures combined. It commonly occurs either after a fall onto a flexed wrist or as a direct blow to the dorsal aspect of the wrist (Fig. 3). One of the diagnostic criteria includes deformed wrist with swelling visible on the volar side and the prominence of the ulna along the dorsum of the wrist [1]. Up to 15% of these fractures may show symptoms related to compression of the median and/or ulnar nerve; therefore, neurovascular evaluation is imperative [2,3].

Standard wrist radiographs are usually adequate to differentiate between Colles and Smith fractures. (Figs. 1,2) [4]. When there is extensive comminution or intra-articular fracture, CT helps define the injury and assist with surgical planning. Disruption of the distal radioulnar joint (DRUJ) and the triangular fibrocartilage complex (TFCC) are often seen along with other soft tissue injuries which are well assessed with MRI [5].

Smith fracture is divided into three types: [6]

• Type I - most common type, accounting for about 85% of cases, is an extraarticular fracture through the distal radius (Fig. 1)

• Type II - less common, accounting for approximately 13%, is an intraarticular oblique fracture, also referred to as a reverse Barton fracture (Fig. 2)

• Type III - uncommon, less than 2%, is a juxta-articular oblique fracture

The mainstay of treatment of non-displaced and stable distal radius fractures is closed reduction and immobilization [6]. Closed reduction using percutaneous pinning with K-wires can be performed in patients with good bone quality and minimal comminution [6,7]. For an unstable or irreducible fracture, ORIF with a volar plate is required [8-11].

Complications include malunion and compression of the median nerve causing carpal tunnel syndrome [12]. Entrapment of the extensor pollicis longus (EPL) tendon with malunion is seen in both conservative and ORIF surgeries [13-15]. Late rupture of the EPL has been demonstrated previously [16, 17]. Similarly development of complex regional pain syndrome (CRPS) has been reported in up to nearly 40% of fractures [18].

References:

1. Shah, H.M. and K.C. Chung, Robert William Smith: his life and his contributions to medicine. J Hand Surg Am, 2008. 33(6): p. 948-51 DOI: 10.1016/j.jhsa.2007.12.020 2. Ford, D.J. and M.S. Ali, Acute carpal tunnel syndrome. Complications of delayed decompression. J Bone Joint Surg Br, 1986. 68(5): p. 758-9. 3. McKay, S.D., et al., Assessment of complications of distal radius fractures and development of a complication checklist. J Hand Surg Am, 2001. 26(5): p. 916-22 DOI: 10.1053/jhsu.2001.26662 4. Dóczi, J., et al., Occult distal radial fractures. J Hand Surg Br, 1995. 20(5): p. 614-7 DOI: 10.1016/s0266-7681(05)80121-4 5. Mills, T.J., Smith's fracture and anterior marginal fracture of radius. Br Med J, 1957. 2(5045): p. 603-5 DOI: 10.1136/bmj.2.5045.603 6. Schroeder, J.D. and M. Varacallo, Smith's Fracture Review, in StatPearls. 2020, StatPearls Publishing Copyright © 2020, StatPearls Publishing LLC.: Treasure Island (FL). 7. Glickel, S.Z., et al., Long-term outcomes of closed reduction and percutaneous pinning for the treatment of distal radius fractures. J Hand Surg Am, 2008. 33(10): p. 1700-5 DOI: 10.1016/j.jhsa.2008.08.002 8. Downing, N.D. and A. Karantana, A revolution in the management of fractures of the distal radius? J Bone Joint Surg Br, 2008. 90(10): p. 1271-5 DOI: 10.1302/0301-620x.90b10.21293 9. Orbay, J.L. and A. Touhami, Current concepts in volar fixed-angle fixation of unstable distal radius fractures. Clin Orthop Relat Res, 2006. 445: p. 58-67 PubMed: https://pubmed.ncbi.nlm.nih.gov/16505728/ DOI:10.1097/01.blo.0000205891.96575.0f 10. Schneppendahl, J., J. Windolf, and R.A. Kaufmann, Distal radius fractures: current concepts. J Hand Surg Am, 2012. 37(8): p. 1718-25 DOI: 10.1016/j.jhsa.2012.06.001 11. Tang, J.B., Distal radius fracture: diagnosis, treatment, and controversies. Clin Plast Surg, 2014. 41(3): p. 481-99 DOI: 10.1016/j.cps.2014.04.001 12. Mackinnon, S.E., Pathophysiology of nerve compression. Hand Clin, 2002. 18(2): p. 231-41 DOI: 10.1016/s0749-0712(01)00012-9 13. Franz, T., Entrapment of Extensor Pollicis Longus Tendon after Volar Plating of a Smith Type Pediatric Distal Forearm Fracture. J Hand Surg Asian Pac Vol, 2016. 21(2): p. 253-6 DOI: 10.1142/s2424835516720085 14. Mansour, A.A., 3rd, J.T. Watson, and J.E. Martus, Displaced dorsal metaphyseal cortex associated with delayed extensor pollicis longus tendon entrapment in a pediatric Smith's fracture. J Surg Orthop Adv, 2013. 22(2): p. 173-5 DOI: 10.3113/jsoa.2013.0173 15. Murakami, Y. and K. Todani, Traumatic entrapment of the extensor pollicis longus tendon in Smith's fracture of the radius-case report. J Hand Surg Am, 1981. 6(3): p. 238-40 DOI: 10.1016/s0363-5023(81)80076-7 16. Bonatz, E., T.D. Kramer, and V.R. Masear, Rupture of the extensor pollicis longus tendon. Am J Orthop (Belle Mead NJ), 1996. 25(2): p. 118-22. 17. Roth, K.M., et al., Incidence of extensor pollicis longus tendon rupture after nondisplaced distal radius fractures. J Hand Surg Am, 2012. 37(5): p. 942-7 DOI: 10.1016/j.jhsa.2012.02.006 18. Li, Z., et al., Complex regional pain syndrome after hand surgery. Hand Clin, 2010. 26(2): p. 281-9 DOI: 10.1016/j.hcl.2009.11.001

Shama Jaswal is an International Medical Graduate, currently doing research at Mallinckrodt Institute of Radiology (MIR), Saint Louis. She aims at pursuing Diagnostic Radiology residency and poses a keen interest in research alongside academics. At MIR, she has been fortunate to work on various oncology projects including the project in which they studied how the difference in fat metabolism in both sexes can affect the cancer survival and outcome, and how this study can further improve prognosis through treatment modification. Shama is both an accomplished sprinter and singer having won several national competitions in in each discipline in India. She also has a strong passion for cooking and gardening.

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Kevin M. Rice, MD is the president of Global Radiology CME

Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.

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