Review of the Traumatic Boutonniere Deformity
A boutonniere deformity is the name of a deformity of the hand caused by an injury to the central slip, resulting in PIP flexion and DIP extension. There are many etiologies of a boutonniere deformity, but the most common two are chronic inflammatory diseases (rheumatoid arthritis) and traumatic injury. The most common etiologies of trauma include open laceration of the central slip tendon, blunt trauma, and volar dislocation of the PIP joint (1/2). The deformity is rather simple to visualize on exam, however it is commonly mistreated or misdiagnosed, leading to delayed treatment and often permanent deformity and/or dysfunction.
Anatomy and Injury
First and foremost, this is not to be confused with a hyperextension injury (jammed finger) causing fixed flexion at the PIP joint. A boutonniere deformity will have extension at the DIP.
To understand the mechanism of the deformity, it is important to understand the anatomy of the extensor tendons of the hand. As the extensor digitorum tendon travels distally, it divides into the lateral band and central slip tendon, which attaches to the proximal portion of the middle phalanx. After central slip tendon injury, there is migration of the lateral bands which causes flexion at the PIP joint and extension at the DIP.
The Elson Test is the most sensitive test for acute boutonniere deformity (4/5). Providers need to flex the PIP to 90 degrees and then ask the patient to extend at the DIP. Under normal conditions with an intact central slip tendon, the DIP cannot be actively extended into plane with the PIP. In the circumstances of central slip tendon injury, the patient is abnormally able to extend at the PIP secondary to a central slip injury.
Plain radiographs of the finger should be obtained in all cases to see subtle DIP hyperextension that can be difficult to detect on exam and to rule out fracture which can complicate management and treatment (3).
Acute and closed injury should be managed with full time splinting of the PIP in extension for 4-8 weeks with active DIP flexion exercises multiple times daily. After 4-8 weeks, providers should introduce PIP exercises and recommend that the patient continue to wear their extension splint at night for an additional 4-6 weeks (3). Acute open injuries need surgical injuries. It is important to note than bony avulsion injuries can complicate management and likely need to be evaluated by a surgeon. Patients that do not improve with nonsurgical methods should also be considered for surgery.
Chronic boutonniere deformities generally have poor outcomes and should only be considered in patients with significant dysfunction.
Boutonniere deformities are caused by an acute injury to the central slip. They are typically diagnosed clinically with the Elson test. Management is typically nonsurgical, with extension splinting of the PIP joint. Referral to hand surgery can be considered for patients who fail conservative measures.
This week’s review was written by Michael Schoeller, DO a second year resident at NCH Healthcare in Naples, Florida. He is currently interested in sports medicine and will be a 2023 applicant for fellowship.
1. Souter WA: The problem of boutonniere deformity. Clin Orthop Relat Res 1974;104:116–133.
2. Strauch RJ: Extensor tendon injury, in Wolfe SW, Hotchkiss RN, Pederson WC, Kozin SH, eds: Green’s Operative Hand Surgery, ed 6. Philadelphia, PA, Elsevier, 2011, vol 1, pp 159–188.
3. McKeon, KE: Posttraumatic Boutonniere and swan neck deformities. Journal of the American Academy of orthopaedic surgeons. 2015, vol 23, issue 10, p 623-632
4. Rubin J, Bozentka DJ, Bora FW: Diagnosis of closed central slip injuries: A cadaveric analysis of non-invasive tests. J Hand Surg Br 1996;21(5):614–616.
5. Elson RA: Rupture of the central slip of the extensor hood of the finger: A test for early diagnosis. J Bone Joint Surg Br 1986;68(2):229–231.
6. Elzinga, Kate, and Kevin C. Chung. “Managing Swan Neck and Boutonniere Deformities.” Clinics in Plastic Surgery, vol. 46, no. 3, July 2019, pp. 329–37. PubMed, https://doi.org/10.1016/j.cps.2019.02.006.