Diagnosing Hook of Hamate Fractures
Introduction
Hook of hamate fractures make up 2-4% of carpal bone fractures (5). The hamate is the most ulnar carpal bone within the distal row of carpal bones (1). The hook of hamate projects in a volar direction into the palm (1). There are multiple attachments to the hook of hamate including the transverse carpal ligament, flexor digiti minimi, and pisohamate ligament (3). The hook of hamate makes up the medial border of the carpal tunnel and lateral portion of the Guyon canal (5).
Hook of hamate fractures occur due to compressive forces that transmit across the hamate during a forceful torque of the wrist (2). These fractures are seen more commonly in tennis, golf, and baseball (2).
Hook of hamate location in relation to a bat grip (9)
Diagnosis
Patients with a hook of hamate fracture will typically complain of ulnar sided palmar pain when they grip an object (2). Any athlete also complaining of flexor tendonitis of the fourth and fifth digit should be evaluated for a hook of hamate fracture that is irritating the tendons during flexion (2). In order to diagnosis the fracture, one clinical exam technique involves putting the wrist in ulnar deviation and then actively having the patient flex the fourth and fifth digits and evaluating for any symptoms (3).
Rarely, a hook of hamate fracture can injure the medial or ulnar nerve, so a thorough neurovascular exam should be obtained in any patient where a fracture is being considered (2). When trying to palpate the hook of hamate, providers should first palpate the pisiform (1). They should then roll their thumb towards the center of the palm and the first bony structure they palpate is the hook of hamate (1).
Palpation of the hook of the hamate (1)
Hook of hamate fractures are difficult to view on standard PA, lateral, and oblique radiographs (2). There are signs of a hook of hamate fracture on standard radiographs including absence of the hook, sclerosis of the hook, and lack of a cortical density (3).
Normal view of the oval ring shadow of the hamate (7)
A carpal tunnel view radiograph can also better show a hook of hamate fracture (3). However, even with a well taken carpal tunnel view, the accuracy of detecting a fracture is as low as 31% (8). A supinated oblique view radiograph with the wrist dorsiflexed can also aid in diagnosis (9).
Carpal tunnel view of the hook of the hamate (5)
A CT scan can detect a hook of hamate fracture with over 97% accuracy (5). An MRI without contrast can also improve accuracy in detection of a hook of hamate fracture compared to standard radiographs (8).
CT image of a hook of the hamate fracture (5)
Conclusion
A hook of hamate fracture should be considered in an athlete complaining of ulnar sided palm or wrist pain. These fractures are more commonly seen in racquet or club/bat type sports. CT scan can provide a more accurate diagnosis than standard radiographs. Treatment can range from conservative to surgical options.
By Gregory Rubin, DO
Rubinsportsmed.com
– More Ankle Pain: https://www.sportsmedreview.com/by-joint/ankle/
– Read more on Wiki Sports Medicine: https://wikism.org/Hamate_Fracture
References
1) Tian, Andrea, and Charles A. Goldfarb. “Hook of Hamate Fractures.” Hand Clinics, vol. 37, no. 4, Nov. 2021, pp. 545–52. PubMed, https://doi.org/10.1016/j.hcl.2021.06.013.
2) Marchessault, Jeffrey, et al. “Carpal Fractures in Athletes Excluding the Scaphoid.” Hand Clinics, vol. 25, no. 3, Aug. 2009, pp. 371–88. PubMed, https://doi.org/10.1016/j.hcl.2009.05.013.
3) Papp, Steven. “Carpal Bone Fractures.” The Orthopedic Clinics of North America, vol. 38, no. 2, Apr. 2007, pp. 251–60, vii. PubMed, https://doi.org/10.1016/j.ocl.2007.03.003.
4) Cohen-Tanugi, Samuel, and Raymond Glenn Gaston. “Examination of Ulnar-Sided Wrist Pain.” Hand Clinics, vol. 37, no. 4, Nov. 2021, pp. 467–75. PubMed, https://doi.org/10.1016/j.hcl.2021.06.002.
5) Davis, Derik L. “Hook of the Hamate: The Spectrum of Often Missed Pathologic Findings.” AJR. American Journal of Roentgenology, vol. 209, no. 5, Nov. 2017, pp. 1110–18. PubMed, https://doi.org/10.2214/AJR.17.18043.
6) Rettig, Arthur C. “Athletic Injuries of the Wrist and Hand. Part I: Traumatic Injuries of the Wrist.” The American Journal of Sports Medicine, vol. 31, no. 6, 2003, pp. 1038–48. PubMed, https://doi.org/10.1177/03635465030310060801.
7) Sanderson, Mark, et al. “The Emergent Evaluation and Treatment of Hand and Wrist Injuries: An Update.” Emergency Medicine Clinics of North America, vol. 38, no. 1, Feb. 2020, pp. 61–79. PubMed, https://doi.org/10.1016/j.emc.2019.09.004.
8) Murthy, Naveen S., and Michael D. Ringler. “MR Imaging of Carpal Fractures.” Magnetic Resonance Imaging Clinics of North America, vol. 23, no. 3, Aug. 2015, pp. 405–16. PubMed, https://doi.org/10.1016/j.mric.2015.04.006.
9) Henderson, Chance J., and Ky M. Kobayashi. “Ulnar-Sided Wrist Pain in the Athlete.” The Orthopedic Clinics of North America, vol. 47, no. 4, Oct. 2016, pp. 789–98. PubMed, https://doi.org/10.1016/j.ocl.2016.05.017.
