Massage therapy · Kitchener–WaterlooBoutonniere Deformity of the Finger

A boutonniere deformity is usually the result of an injury to the tendon on the top of the finger that straightens the middle joint, so the finger cannot straighten fully (AAOS, n.d.). The middle joint of the finger stays bent, while the tip of the finger bends backward. This shape is the classic sign of a boutonniere deformity. When a deformity caused by injury is treated promptly, it can usually be reversed; if it is not treated, it can get worse, and impaired function and permanent deformity can result (AAOS, n.d.).

The main cause is a forceful blow to the top of a bent middle finger joint, or a dislocation of that joint, which tears the tendon or breaks off the small piece of bone it attaches to (AAOS, n.d.). Another cause is a cut to the top of the finger from a tool or knife, which can sever the tendon. Boutonniere means "buttonhole" in French, because the torn tendon can look like a buttonhole (AAOS, n.d.).

Boutonniere Deformity Anatomy

Several tendons in the finger work together to straighten and bend the finger. These tendons run along the bottom, sides and top of the finger. The main part of the tendon on the top of the finger, called the central slip, attaches to the finger's middle bone and straightens the middle joint. When that tendon is injured, the finger can't straighten out fully. Over time, the tendons on the sides of the finger slip towards the palm side, which makes the deformity worse and pulls the fingertip backward (AAOS, n.d.).

How to Treat a Boutonniere Deformity

Your doctor or hand therapist may recommend stretching exercises to improve the strength and flexibility of your fingers. If your finger is in a splint, exercises usually focus on bending the fingertip joint; follow the exercises you have been given (AAOS, n.d.). I can support their plan with hands-on work, exercises and, later, taping. See the My Approach tab for how I work.

Protection

If you play sport, you may need to wear protective splinting or taping for a while after your splint is removed (AAOS, n.d.). I can help with taping for sport once your doctor or hand therapist is happy for you to play.

Treatments you may want to discuss with your family doctor or nurse practitioner

Tips

• If you have been given a splint, wear it exactly as your clinician tells you. Letting the middle joint bend while the splint is off during treatment can undo the progress you have made (AAOS, n.d.).
• Boutonniere deformities are often caused by your finger taking a forceful blow.
• Cuts on the top of the finger can sever the central slip from where it is attached to the bone. In some cases, the bone can poke through the cut, which needs emergency care.
• Arthritis, most commonly rheumatoid arthritis, can also cause a boutonniere deformity (AAOS, n.d.). It is a well-known hand problem in rheumatoid arthritis, although only a minority of people with the condition develop it (Yang et al., 2026).
• Signs of the deformity can appear immediately after an injury, or develop over the following weeks (AAOS, n.d.).
• If the deformity is left untreated for more than 3 weeks, it becomes much more difficult to treat (AAOS, n.d.).

With a boutonniere injury, the tendon on top of the middle finger joint has to heal with that joint held straight. Your doctor or hand therapist decides how long the splint stays on and which exercises you do, and I work strictly alongside their plan. If you've had surgery, I need your surgical team's okay before we start any hands-on treatment.

I start by assessing how your hand, wrist, elbow and shoulder are moving, and checking exactly what you've been cleared to do.

While Your Finger Is Splinted

• Easing the forearm, upper arm, neck and shoulder, which often tense up while the hand is protected
• Keeping your hand raised and the other fingers, wrist and elbow moving, to help with swelling and stiffness
• Supporting the fingertip exercises you've been given, without ever letting the middle joint bend
• The splint stays on exactly as instructed

Once You're Cleared

1. American Academy of Orthopaedic Surgeons (AAOS) (n.d.) Boutonnière deformity. OrthoInfo. Available at: https://www.orthoinfo.org/en/diseases--conditions/boutonniere-deformity/ (Accessed: 7 October 2026).
2. Yang, Y., Lin, J.-Z., Zou, Y.-W. et al. (2026) 'Association of biologic/targeted-synthetic DMARDs with a lower prevalence of hand joint deformity in rheumatoid arthritis: a cross-sectional real-world study', Medicina, 62(2), 241. doi: 10.3390/medicina62020241