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June 16, 2021 5 min read

Answer a fun quick question about Boutonniere Deformity, learn more about what defines this particular deformity and find some helpful tips on the best hand therapy treatment for Boutonnière deformity.

Answer this Quick Question

Hyperflexion of the PIPJ with hyperextension of the DIPJ is known as what?

a) Mallet finger
b) Swan-neck deformity
c) Fixed flexion deformity
d) Boutonnière deformity

Answer: d) Boutonnière deformity

What is a Boutonniere deformity?


A Boutonniere deformity results from a  Zone III extensor tendon (central slip) injury, and presents as PIP flexion and DIP hyper-extension.

It gets its name from the "button-hole" appearance ("Boutonniere" in French).

It is caused by disruption of the central slip over the PIP joint, which can happen in several ways, such as laceration, closed rupture / traumatic avulsion (jammed finger), or capsular distension

(e.g. in rheumatoid arthritis).




    1. When the central slip is ruptured / lacerated, EDC cannot extend the PIPJ.
    2. There may also be attenuation of the triangular ligament.
    3. The lumbricals act as flexors at the PIP joint, while also extending the DIP joint without an opposing force.
    4. There is palmar migration of the lateral bands.
    5. The lumbricals' pull becomes unopposed, pulling through the base of the distal phalanx and volar to the PIP joint.
    6. This causes PIP flexion and DIP extension
    7. (Be aware: “pseudo-boutonniere” refers to PIP joint flexion contracture in the absence of DIP extension)

    Why does this happen?
    To understand the deformity, you have to understand the ANATOMY!


    1. Lumbrical muscles: originate from the FDP and insert onto the lateral bands.
    2. EDC tendon joins the extensor hood at the MCP and the central portion forms the central slip.
    3. Central slip inserts onto the middle phalanx and acts to extend the PIP joint.
    4. Lateral bands are formed from the deep head of the dorsal interossei combining with the volar interossei.
    5. The lateral bands insert onto the base of the distal phalanx to extend the DIP joint.


    1. Triangular ligament spans the two lateral bands, preventing them from subluxing volarly.
    2. Transverse retinacular ligament prevents dorsal subluxation of the lateral bands

     Boutonniere Deformity

    The best way to test the central slip is "Elson's test" (even before any deformity becomes evident)

    • client places hand palm down over the edge of a table and bends the PIPJ to 90deg.
    • clients tries to actively extend the middle phalanx against resistance.
    • if the central slip is disrupted, there will be little or no PIP extension and the DIP may stiffen. 

    Hand Therapy for Boutonnière deformity


    If there is a closed injury (i.e. not a laceration) and you are seeing the client in the first 4/52 post injury:

    • Splint the PIP joint in full extension for 6 weeks. This is so the 2 ends of the tendon can make contact and heal with scar tissue.
    •  It takes at least 6/52 for this to happen and for the scar tissue to be strong enough for us to start the PIPJ moving.
    • During these 6/52, encourage active DIP extension and flexion in splint to avoid contraction of oblique retinacular ligament
    • gradually wean from splinting over the following 4-6 weeks, gradually allowing increasing AROM of the PIPJ. 


    Surgery may be required if there is an acute displaced avulsion fracture or an open wound, or in chronic injuries that have full PROM but can still not actively extend the PIPJ, or in a rheumatoid patient with a painful, stiff, arthritic PIP joint.

      Post-op hand therapy depends on your surgeon’s protocols, but usually:

      • within the first week post op, fabricate a finger cylinder splint (DIPJ free if no lateral band involvement, or DIPJ included if lateral bands also repaired). Continue this splint for 6/52. DIPJ AROM exercises if no lateral band involvement. 
      • At around 4/52 post repair, the splint can be removed for AROM, starting with a  template at 30deg flexion, gradually increasing by 10-15deg each week, provided there is no extension lag. 
      • Continue the splint until 12/52 both at night and during "at-risk" activities (e.g. sports).
      • If the PIPJ is still stiff, or there remains a fixed flexion deformity, try a dynamic PIPJ extension splint. 

      Here are our most popular PIPJ extension splints








      View this helpful video

      Watch Alison demonstrate the Promedics Capener splint with its coil design to provide 3 point pressure along with the Mediroyal LMB Finger Splint.

      Here are my top 3 hand therapy techniques for managing a Boutonnière deformity:

        1. Get on top of PIPJ swelling as soon as possible! This is often a big contributing factor to the limited AROM. Ice works well for some in the acute stage, but once the initial inflammatory response has settled, consider heat (like a wheat-bag or a soothing dip in the wax bath), gentle soft tissue massage, and light compression. You could try the Oedema Finger Sleeve or the Redi-Fit Digi Sleeve.

        2. BE GENTLE! With finger injuries, particularly grumpy PIP joints, it is never a case of "no pain no gain". An overzealous therapist or client pushing the PIPJ too hard, just results in increased swelling, pain and stiffness, which is totally counterproductive! Make sure you and the client understand the concept of LLPS (low load prolonged stretch) - this is the only way to achieve a plastic change (i.e. new tissue growth) rather than an elastic change (stretching the existing soft tissues temporarily, so they go back to pre-stretch length shortly after the load is removed). You could try an LMB splint, or for a grumpy joint, try the Capener splint, which is less forceful and often better tolerated.

        3. Work on achieving active PIPJ extension as soon as AROM is allowed. Often the client wants to focus on flexion, but that usually comes back easily. The harder job is getting full PIPJ extension actively (i.e. getting the central slip and lateral bands working collaboratively again). Work on gaining PIPJ extension in the tabletop position (MCPJs flexed, IPJs extended) , or use the Elson's test (previously described) as a therapy activity, not just a test.

      You could also try: 

      1. Prevention is better than cure, so the goal of hand therapy is to prevent a central slip rupture from developing into a fixed Boutonniere deformity with PIPJ contracture.  But if the client has presented late, or has developed a PIPJ contracture despite your best efforts,  act as soon as possible (remember scar tissue starts being laid down around 3 days post-injury / surgery and may continue being laid down and remodelled for many months!). If the contracture is <30deg, the above splints are perfect. If contracture is >30deg you may need to try a circumferential thermoplastic splint or even serial Plaster of Paris (PIP POP) casting. By changing the cast at least twice per week, a good reduction in swelling and contracture can be achieved within 2-3 short weeks.

      2. If AROM PIPJ extension lag continues, you could try a relative motion splint. This yolks the affected digit to its adjacent digits, blocking the dorsum of the proximal phalanx of the affected digit, relative to the adjacent digits. Thus when the fingers extend, the force of the affected digit is transmitted to the central slip, rather than MCPJ hyperextension.



      What are your tips for treating Boutonniere Deformity?

      This blog is a discussion format. We have listed our views above but would love to know what you think, what your comments are or how you best treat Boutonniere Deformity in your practice. Feel free to email us at