Scaphoid tubercle and waist fracture

19 yo M who fell • Xray of the Week

Figure 1. Describe the wrist injury.

Figure 2.

A. Plain radiograph of the wrist demonstrating subtle fracture of the waist of the scaphoid (yellow arrow) and nondisplaced fracture of the scaphoid tubercle (red arrow).

B. Coronal CT scan of the wrist demonstrating the minimally displaced fracture of the scaphoid tubercle (red arrow).

C. Axial CT scan of the wrist demonstrating the minimally displaced fracture of the scaphoid tubercle (red arrow).

D. Coronal CT scan of the wrist demonstrating the minimally displaced fracture of the waist of the scaphoid. (yellow arrow).

Figure 3. Mayo Clinic Scaphoid Fracture Classification: Scaphoid bone fractures are classified by anatomic position. The location of the fracture is significant because the decreasing blood flow distal to proximal can lead to complications in healing (such as AVN). Diagram by Nirali Dave.

Figure 4. Volar view of scaphoid blood supply. Superficial Palmer Branch of Radial Artery enters the scaphoid bone distally around the tibial tuberosity and provides 20-30% of the blood supply. Diagram by Nirali Dave.

Figure 5. Dorsal view of scaphoid blood supply. Dorsal Carpal Branch of Radial Artery enters scaphoid bone through the dorsal ridge and provides 70-80% of the blood supply with thinner branches proximally. Diagram by Nirali Dave.

Discussion:

Scaphoid fractures have been well-reported as a challenge to diagnose and treat. Patients with scaphoid fractures usually present with severe wrist pain, swelling, and decreased range of motion following high-energy trauma. Anatomical snuffbox tenderness, pain on axial compression of the thumb, and scaphoid tubercle tenderness have extremely high sensitivity for scaphoid fractures, but have variable specificity [1,2].

The initial imaging modality used to diagnose scaphoid fractures is plain radiography, however x-rays can miss up to 30% of fractures in the acute setting. If clinical suspicion of a scaphoid fracture is high but no fracture is seen on x-ray, the appropriate next step is CT scan [1-3].

The Mayo classification system for scaphoid fractures is organized according to anatomic location in the scaphoid bone: proximal third, middle third (waist), distal third (Fig. 3). Of these, proximal third fractures account for 10% of all scaphoid fractures, waist fractures account for 70%, and distal third fractures account for 20% [4]. Distal tubercle fractures are rare, accounting for only 5% of all scaphoid fractures and are visualized on x-rays as avulsed small radiovolar fragments of the distal tip [4,5].

The distal third of the scaphoid bone receives its blood supply from radial artery branches (Figs. 4-5); therefore, healing of a distal tubercle fracture usually proceeds without complication. Since the remainder of the scaphoid bone depends on the blood supply from the distal third of the scaphoid, vascular disruption due to a scaphoid waist fracture may result in complications such as nonunion, avascular necrosis, and chronic radiocarpal osteoarthritis [6].

Because there is excellent vascularity found in the distal third of the scaphoid bone, patients with scaphoid tubercle fractures are normally treated with immobilization in a thumb spica short cast, with full recovery taking about 4-6 weeks. Conversely, scaphoid fractures of the proximal third and waist can have more protracted healing timelines. If imaging indicates a non-displaced scaphoid waist fracture, minimally invasive percutaneous screw fixation has achieved promising results. More unstable scaphoid fractures often require open operative treatment that can still result in complications such as delayed or nonunion [6,7].

References:

1. Puopolo SM, Rettig ME. Management of acute scaphoid fractures. Bulletin of the NYU Hospital for Joint Diseases. 2003;61(3,4). http://hjdbulletin.org/files/archive/pdfs/681.pdf

2. Platon A, Poletti P-A, Aaken J, et al. Occult fractures of the scaphoid: the role of ultrasonography in the emergency department. Skeletal Radiology. 2011;40(7):869-875. doi:10.1007/s00256-010-1086-y

3. Kaewlai R, Avery LL, Asrani AV, et al. Multidetector CT of carpal injuries: anatomy, fractures, and fracture-dislocations. Radiographics : a review publication of the Radiological Society of North America, Inc. 2008;28(6):1771-1784. doi:10.1148/rg.286085511

4. Gupta V, Rijal L, Jawed A. Managing scaphoid fractures. How we do it? Journal of Clinical Orthopaedics and Trauma. 2013;4(1):3-10. doi:10.1016/j.jcot.2013.01.009

5. Prosser AJ, Brenkel IJ, Irvine GB. Articular Fractures of the Distal Scaphoid. Journal of Hand Surgery (British and European Volume). 1988;13(1):87-91. doi:10.1016/0266-7681(88)90061-7

6. Clementson M, Björkman A, Thomsen NOB. Acute scaphoid fractures : Guidelines for diagnosis and treatment. Efort Open Reviews. 2020;5(2):96-103. doi:10.1302/2058-5241.5.190025

7. Rhemrev S, Ootes D, Beeres F, Meylaerts S, Schipper I. Current methods of diagnosis and treatment of scaphoid fractures. International Journal of Emergency Medicine. 2011;4(1):1-8. doi:10.1186/1865-1380-4-4

Nirali Dave is a medical student at Medical University of Lublin in Poland, currently doing clinical rotations in New York. Before that she completed her undergraduate education at Rutgers University, and worked as a medical scribe. Nirali was first exposed to basic radiologic imaging while scribing, and was very quickly taken by the field. Her passion for radiology comes from the bridging of anatomy, health technologies, and patient care. In the future, she hopes to complete a diagnostic radiology residency and stay committed to clinical research and patient education. Update 2022: Dr. Dave is a Radiology Resident at Indiana University School of Medicine.

Follow Nirali Dave on Twitter @ndave08

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Kevin M. Rice, MD is the president of Global Radiology CME and is a radiologist with Cape Radiology Group. Formerly the 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. He was once again a semifinalist for a "Minnie" for 2021's Most Effective Radiology Educator by AuntMinnie.com.

Follow Dr. Rice on Twitter @KevinRiceMD

All posts by Kevin M. Rice, MD