Hook of Hamate Fracture
Updated: Nov 6, 2022
48 yo male wrist pain following a MVA with persistent pain for one month • Xray of the Week
The patient's hand was on the horn at time of impact and the steering wheel mounted airbag deployed, contributing to the injury. Normal wrist xray. Persistent pain for one month, then had an MRI.
Figure 1. Describe the wrist injury.
Figure 2. MRI of Hook of hamate fracture.
A. Axial T1-weighted image demonstrates the body of the hamate (blue arrow), the hook of hamate (green arrow), and a fracture through the base of the hook of the hamate (yellow arrow).
B. Axial fast spin echo proton density image with fat saturation demonstrates the body of the hamate (blue arrow), the hook of hamate (green arrow), and a fracture through the base of the hook of the hamate (yellow arrow). There is also high signal in the distal hamate due to edema
C. Coronal STIR image demonstrates high signal in the distal hamate due to edema (red arrow).
Discussion:
Hamate fractures are rarely encountered carpal bone fractures, comprising approximately 2% of all carpal bone fractures (1,2). Anatomically, the hamate bone is found in the distal carpal row situated at the ulnar aspect of the wrist. It is wedge-shaped and has a bony prominence at the volar aspect regarded as the hook of hamate. Hamate fractures can be broadly divided into two groups according to Milch’s classification: hamate body fractures and hook of hamate fractures (2). Hook of hamate fractures are further subdivided according to their location in the hook: Type 1 fractures are located at the distal hook, type 2 at the middle, and type 3 are located at the base of the hook. Type 3 fractures account for the majority of hook of hamate fractures (6). High impact injuries--when rigid objects strike the hand--as seen in a fall or blunt trauma, can result in hamate fractures. Sporting injuries involving repetitive motions with equipment such as golf clubs, rackets, and baseball bats are also associated with hamate fractures, and are seen most frequently in younger men. Patients can present with pain and tenderness over the hypothenar eminence with limited wrist range of motion (2,3).
Initial radiographs obtained at the first visit are often negative due to difficulty capturing the appropriate view of the fractured hamate bone (3,6). If the initial radiographs are negative, patients may continue to experience pain and follow up to get more advanced imaging such as CT or MRI. CT scans have very high sensitivity and specificity for picking up all types of hamate fractures. MRI is the imaging modality of choice for radiographically occult hamate fractures because of its high sensitivity for bone marrow signal irregularities and can display associated ulnar nerve or flexor tendon findings (3,4). In this case, the axial images reveal a linear signal abnormality at the base of the hook (Figs. 1,2), consistent with a type 3 fracture of the hook of the hamate (3-6).
Complications of a long-standing fracture without treatment include flexor tendon rupture, nonunion, and chronic post-traumatic osteoarthritis (5). The standard treatment for nondisplaced hook of hamate fractures immobilization via ulnar gutter splint (3-6). Displaced hamate body fractures commonly require open reduction and internal fixation (ORIF). Surgical excision of the hamate hook fragment is used for symptomatic displaced fractures, nonunion, and nondisplaced hook fractures older than 3 months (3-6). In this particular case, after several months of conservative management and persistent non-union, this patient underwent excision of the hook, resulting in alleviation of his pain.
References:
1. Cecava ND, Finn MF, Mansfield LT. Subtle radiographic signs of hamate body fracture: a diagnosis not to miss in the emergency department. Emergency Radiology. 2017;24(6):689-695. doi:10.1007/s10140-017-1523-5
2. Arthur J, Jorgensen SA, Towbin AJ, Towbin R. Hook of the hamate fracture. Applied Radiology. 2018;47(2):29-31. Hook of the hamate fracture. https://www.appliedradiology.com/articles/hook-of-the-hamate-fracture
3. O’Shea K, Weiland AJ. Fractures of the Hamate and Pisiform Bones. Hand Clinics. 2012;28(3):287-300. doi:10.1016/j.hcl.2012.05.010
4. Mandegaran R, Gidwani S, Zavareh A. Concomitant hook of hamate fractures in patients with scaphoid fracture: more common than you might think. Skeletal Radiology. 2018;47(4):505-510. doi:10.1007/s00256-017-2814-3
5. Snoap T, Habeck J, Ruiter T. Hamate Fracture. Eplasty. 2015;15:ic28. Hamate Fracture. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462833/
6. Davis DL. Hook of the Hamate: The Spectrum of Often Missed Pathologic Findings. AJR 2017; 209:1110–1118. doi:10.2214/AJR.17.18043
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.
Follow Nirali Dave on Twitter @ndave08
Kevin M. Rice, MD is the president of Global Radiology CME
Dr. Rice is a radiologist with Cape Radiology Group. Formerly the Chief of Staff at 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
