Review on Injuries to the Sagittal Bands
Introduction
The sagittal bands are one of the components of the dorsal hood, which is the support structure for the extensor tendon at the level of the dorsal metacarpophalangeal joint (MCP) (1). The other structures that make up the dorsal hood are the oblique and transverse bands (1). The sagittal bands are the thickest structures of the extensor hood and act as the main resistance for proximal displacement of the extensor tendon (1). Intact sagittal bands will prevent radial-ulnar subluxation of the extensor tendon and also aid in MCP extension (2, 3). The sagittal bands are broken into a superficial and deep layer that allows the tendon to run through the bands (1). The sagittal bands will form a sling around the tendon and then attach to the volar plate (3).
Injury to the sagittal bands are typically seen in boxer’s knuckle, which is defined as a tear of the MCP joint capsule that usually is accompanied by a rupture of the sagittal bands (4). The third MCP is most typically affected in a boxer’s knuckle (6).
White arrows represent the fibers of the sagittal bands (1)
Diagnosis
Injury to the sagittal bands can be acute or chronic. A blunt trauma to the MCP joint can cause partial tear or complete rupture of the sagittal bands (3). Even low energy activities, like flicking the finger, can cause acute injury to the sagittal bands (6). Patients will typically complain of extensor tendon instability (2). They also may complain of a snapping localized to the MCP joint (2). On physical exam, the provider should evaluate for tendon subluxation and dislocation with flexion and extension of the affected MCP joint. The tendon will typically subluxate in the ulnar direction with flexion of the MCP joint (4). The MCP joint may also show joint swelling and/or tenderness over the dorsum of the MCP joint (4).
The classification for sagittal band injury is the Rayan and Murray classification (3). Type I injuries have no tear, but a contusion to the bands. Type II injuries have subluxation of the extensor tendon and Type III involve dislocation of the tendon between the metacarpal heads (3).
Image A shows interruption of the superficial fibers and image B shows disruption of the superficial and deep fibers (6)
Standard radiographs that involve three views of the hand should be done if there has been acute trauma to rule out a fracture (5). MRI can also help confirm tearing of the sagittal bands (6). Ultrasound can also evaluate the extensor tendon for subluxation during dynamic motion (7).
Treatment
Treatment for acute sagittal band injury is typically conservative. Acute sagittal band injuries can be managed with an MCP joint extensor splint (2). Typically, the extension splint should be worn for 6 weeks (3). There are custom extension splints that can be made by an occupational hand therapist as well (3). These are typically flexion block splints that can be worn for up to 8 weeks (4). A sagittal band injury with no tendon instability can be treated with buddy taping (4).
MCP flexion block splint (4)
Sagittal bands splint with bridge avoids flexion (7)
Sagittal band injuries that continue to have subluxation or dislocation after a period of immobilization are candidates for primary repair (3).
Conclusion
The sagittal bands are an important member of the extensor compartment and act as the primary resistance of the extensor tendon at the level of the MCP joint. Injury can be acute vs. chronic and is usually treated with 8 weeks in an extension splint. Surgery can be considered in those patients with chronic instability of the extensor tendon who fail conservative measures.
By Gregory Rubin, DO
rubinsportsmed.com
References
1) Willekens, Inneke, et al. “Ultrasound Follow-up of Posttraumatic Injuries of the Sagittal Band of the Dorsal Hood Treated by a Conservative Approach.” European Journal of Radiology, vol. 84, no. 2, Feb. 2015, pp. 278–83. PubMed, https://doi.org/10.1016/j.ejrad.2014.11.001.
2) Roh, Young Hak, et al. “Prognostic Factors for Nonsurgically Treated Sagittal Band Injuries of the Metacarpophalangeal Joint.” The Journal of Hand Surgery, vol. 44, no. 10, Oct. 2019, p. 897.e1-897.e5. PubMed, https://doi.org/10.1016/j.jhsa.2018.11.011.
3) Matzon, Jonas L., and David J. Bozentka. “Extensor Tendon Injuries.” The Journal of Hand Surgery, vol. 35, no. 5, May 2010, pp. 854–61. PubMed, https://doi.org/10.1016/j.jhsa.2010.03.002.
4) Lin, James D., and Robert J. Strauch. “Closed Soft Tissue Extensor Mechanism Injuries (Mallet, Boutonniere, and Sagittal Band).” The Journal of Hand Surgery, vol. 39, no. 5, May 2014, pp. 1005–11. PubMed, https://doi.org/10.1016/j.jhsa.2013.11.018.
5) Kenney, Raymond J., and Warren C. Hammert. “Physical Examination of the Hand.” The Journal of Hand Surgery, vol. 39, no. 11, Nov. 2014, pp. 2324–34; quiz 2334. PubMed, https://doi.org/10.1016/j.jhsa.2014.04.026.
6) Sivakumar, Brahman, et al. “Sagittal Band Injuries: A Review and Modification of the Classification System.” The Journal of Hand Surgery, vol. 47, no. 1, Jan. 2022, pp. 69–77. PubMed, https://doi.org/10.1016/j.jhsa.2021.09.011.
7) Kleinhenz, Benjamin P., and Brian D. Adams. “Closed Sagittal Band Injury of the Metacarpophalangeal Joint.” The Journal of the American Academy of Orthopaedic Surgeons, vol. 23, no. 7, July 2015, pp. 415–23. PubMed, https://doi.org/10.5435/JAAOS-D-13-00203.
