18 year old male. Trauma due to punching a punching bag • Xray of the Week
Figure 1. What is the important finding on this xray.
Figure 2. Frontal, lateral, and oblique radiographs showing hamate body fracture (red arrows) due to the patient punching a punching bag.
Hamate fractures represent around 2-4% of all carpal fractures (1). Fractures involving the hamate bone can be divided into two broad categories. Type I is a hook of the hamate fracture and type II involves the body (Figs. 1,2). Type I can be specified under three subtypes depending if they involve the base, the waist, or is an avulsion of the tip (2). The type II hamate fracture can be either 2a which is a coronal fracture, dorsal oblique, or splitting, or 2b which is transverse. Mechanisms of injury may be related to sports (especially tennis, baseball and golf) which fracture the hook, and body fractures are most commonly from punch injuries as seen in this case (2).
Although hamate fractures can be identified on hand radiographs, sometimes they may be difficult to diagnose. A missed diagnosis in the ED often delays orthopedic involvement which can result in long term functional disabilities and can destabilize the fourth and fifth carpometacarpal joints (3). Cecava and colleagues identified six potential radiographic signs of a hamate fracture: 1) distal dorsal hamate avulsion fragment, 2) noncongruent metacarpal alignment, 3) fourth/fifth CMC joint obscuration, 4) disruption or obscuration of hamate hook ring, 5) hamate double density sign, and 6) ulnar and dorsal soft tissue hand swelling (3). They also correlated these findings to their respective findings on CT. If these radiographic findings and clinical findings indicate a hamate fracture, a CT is the preferred imaging modality to thoroughly classify these fractures (3). A study showed that radiographs of hamate fractures were around 72% sensitive with 89% specificity. A high resolution CT showed to have 100% sensitivity and 94% specificity (4).
With acute nondisplaced hook fractures, immobilization with an ulnar gutter cast for 6 weeks may be sufficient. Displaced fractures usually require open reduction and internal fixation or excision of the bony fragment. Nonunion fractures require pinning with bone grafting. Acute nondisplaced and displaced fractures of the body of the hamate have similar treatments as hook fractures (1-4).
Goliver JA, Adamow JS, Goliver J. Hamate body and capitate fracture in punch injury. Am J Emerg Med. 2014 Oct;32(10):1303.e1-2.. Epub 2014 Apr 3. PMID: 24792935. doi:10.1016/j.ajem.2014.03.050
Mouzopoulos G, Vlachos C, Karantzalis L, Vlachos K. Fractures of hamate: a clinical overview. Musculoskelet Surg. 2019 Apr;103(1):15-21. Epub 2018 May 29. PMID: 29845407. doi:10.1007/s12306-018-0543-y
Cecava ND, Finn MF, Mansfield LT. Subtle radiographic signs of hamate body fracture: a diagnosis not to miss in the emergency department. Emerg Radiol. 2017 Dec;24(6):689-695. Epub 2017 Jun 14. PMID: 28616787. doi:10.1007/s10140-017-1523-5
Andresen R, Radmer S, Sparmann M, Bogusch G, Banzer D. Imaging of hamate bone fractures in conventional X-rays and high-resolution computed tomography. An in vitro study. Invest Radiol. 1999 Jan;34(1):46-50. PMID: 9888053. doi:10.1097/00004424-199901000-00007
Neal Joshi is a medical student and aspiring diagnostic radiologist at Rowan University School of Osteopathic Medicine in New Jersey. Prior to medical school, he did research with mouse models for Parkinson’s disease and L-DOPA induced dyskinesias. He also did an internship at Kessler Institute for Rehabilitation in a stroke lab analyzing MR images in ischemic stroke patients with hemispatial neglect. During his time at Rowan, he did research with animal models for traumatic brain injury with an emphasis on electrophysiology of neurons. He graduated from William Paterson University where he completed his studies in biology and biopsychology. Apart from medical school, Neal loves to read, skateboard, go on hikes, and spend time with his friends.
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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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