BOUTONNIERE DEFORMITY

Hyperflexion in the proximal interphalangeal (PIP) joint and hyperextension in the distal interphalangeal (DIP) joint produces a deformity called boutonniére (French for “buttonhole”). The boutonniére deformity is a sequela a extensor tendon injury at the PIP joint level.  The central slip tears and migrates proximally.  The triangular ligament is damaged and the lateral bands displace volarly below rotational axis of the PIP joint.  The resultant damage to the extensor hood, triangular ligament and PIP joint capsule produces a button hole defect dorsally.  As the bony structures displace dorsally through the button hole defect, the lateral bands move further volarly and the tendon balance is disrupted.  This is often followed by a fixed PIP joint flexion cntracture and DIP joint hypertension.³ Such an injury may be caused by a laceration of the central slip and dorsal PIP joint capsule but usually buttoniere injuries occur after closed ruptures of the central slip secondary to a severe hyperflexion force appied to the PIP joint. Without treatment within 3 weeks of the initial injury, the misalignment becomes fixed, chronic, and more difficult to treat. Even with treatment, this deformity can have long-lasting consequences, including persistent stiffness, flexion contracture, chronic swelling, and impaired mobility.

Common causes of the event cascade that leads to boutonniére deformity include:

• Forceful blow causing uncontrolled forceful flexion of the PIP joint that ruptures the central slip
• Laceration that severs the central slip and dorsal capsule
• Arthritis with synovitis that damages the PIP joint ligaments and tendons. Boutonniere deformity is not uncommon in rheumatoid arthritis secondary to the synovitis which damges the central slilp.

Pathophysiology

• Boutonniére deformity results from a closed or open extensor-tendon injury at the level of a finger’s PIP joint (zone III). With disruption of the central slip of the extensor tendon, the lateral bands sublux volarly upon flexion. This volar subluxation develops into a increasing PIP joint extension lag, and the lateral bands may become fixed volarly.
• The injured central slip allows the lumbrical and interosseous muscles to pull the lateral bands proximally, increasing tension on the terminal tendon and hyperextending the DIP joint.

Related Anatomy

• DIP joints
• Central slip of extensor tendon
• Interosseous muscles
• Lateral bands
• Lumbrical muscles
• PIP joint
• The triangular ligament

Incidence and Related Conditions

• Associated extensor tendon injuries and volar PIP joint dislocations are common.
• A swan-neck deformity can also result from PIP joint injuries

Differential Diagnosis

• Mallet finger
• Swan-neck deformity
• PIP joint subluxation or dislocation
• PIP volar plate injuries (Pseudo-bountonniere)

The typical patient with a traumatic boutonniére deformity is usually a young active individual (male or female) who has injuried their finger while playing sports. The patient presents complaining of a "jammed finger".  Usually, the patient will be complaining about PIP joint pain and swelling. Initially, the PIP joint extension lag may be minor but if the injury is left untreated,  the extension lag will increase and eventually become a fixed PIP joint flexion contracture (i.e. boutonniere deformity).  

RECOMMENDED HAND SURGEON THERAPY ORDERS

• Edema control
• Patient education on prevention of further tendon injury and precautions to avoid disruption of a healing central slip.
• PIP extension splinting for prolonged conservative management.
• Isolated active range of motion exercises, blocking and reverse blocking exercises for the PIP joint under a therapist's supervision.
• Post-operative massage with bacitracin until 48 hours after suture removal, then switch to vitamin E cream for open central slip repairs
• Tendon gliding exercises when allowed
• Begin strengthening exercises at 8-10 weeks after splinting has been discontinued
• Scar conformer splinting if scar is hypertrophic if applicable
• Progressive PROM stretches when applicable which may include dynamic splinting or straps
• Work Hardening / work simulation if necessary

REVIEW OF THERAPIST COSERVATIVE INTERVENTIONS FOR BOUTINNIERE DEFORMITY (ZONE 3 EXTENSOR TENDON INJURY)

Therapy for non-operative patient to include:

Full time splinting of PIP for weeks in full extension (splinting for 6 weeks and then check for a lag.  If no extension lag at PIP presents, you may order part time day splint use (30-60 minute intervals) and full night time splint use for an additional 2 weeks.  If a slight extension lag persists, continue full time PIP splint use for an additional 2 weeks.  Night extension splinting can be maintained for a total of 3-4 months if necessary to counterbalance flexion postures during the day.

• Prefab, alumo-foam, or custom splint fabrication by an Occupational Therapist or Physical Therapist / Certified Hand Therapist.  Custom splints may provide more proper fit and comfort, to immobilize the PIP joint, but allow full DIP joint AROM. (see image)
• Patient should return 1x per week for splint checks and skin checks, until week 6.
• Full AROM is initiated during week 1 to encourage DIP and MCP joint gliding.
• At week 6, initiate PIP AROM blocking exercises for PIP within reported pain free range and gradually progress to tendon gliding through the next 2-4 weeks. (limit full composite flexion to prevent early overstretching)
• At week 8, initiate composite rapid full fist, and continue tendon gliding & blocking exercises to encourage composite end range AROM within reported pain free range. (see image)
• Encourage towel wringing exercises with warm water to full functional use.
• Take breaks, ice x 10 minutes intermittently throughout the day.
• At 8-10 weeks, gentle progressive resistant exercises may be initiated.

REVIEW OF POST OPERATIVE INTERVENTIONS FOR BOUTINNIERE DEFORMITY - NOT INCLUDING SHORT ARC EARLY AROM (ZONE 3 EXTENSOR TENDON INJURY)

Early hand therapist assistance and intervention:

• At week 1-4, dressing assessment and changing with oil embedded dressings to keep the surgical site clean and dry.  Check skin for signs of infection and educate patient.
• Edema control – encourage elevation, encourage early gentle finger ROM, watch for RSD/CRPS signs.
• Very light compressive sleeves for fingers and/or hand.  Be aware of the tourniquet effect causing distal edema accumulation and restricted blood flow to the surgical site.
• Patient education – teach signs of infection, avoid maceration of surgical site, encourage a smoke free recovery, avoid excessive exercise to minimize scarring and avoid power flexion at the PIP joint until the central slip heals completely.
• Encourage AROM to uninvolved fingers as tolerated to optimize AROM and minimize edema.
• At week 4, referral to an Occupational Therapist or Physical Therapist / Hand Therapist for protective splinting.  Custom splint fabrication may provide full extension posture with a circumferential gutter PIP and DIP extension splint. (see image)
• At week 4, initiate AROM blocking exercises for the PIP and DIP, focusing on isolated joint motion for each.  Reverse blocking (Active PIP extension while supporting MCP’s in flexion) may also be initiated to focus on regaining PIP extension. (see image)
• At week 4, initiate tendon gliding exercises only within patients’ comfort to avoid early tendon overstretching. (see image)
• At week 6, initiate gentle PROM to involved finger(s) to maximize functional grasp and AROM. Introduce tendon gliding exercises a few times per day to minimize stiffness from the splinting, with intermittent splinting as depicted in the conservative management section.
• At week 7-8, initiate self stick flexion wrapping, static progressive or dynamic splinting with MCP block splint, velcro flexion strap, or flexion golf glove to maximize PROM and ultimately AROM.   Be sure to look out for an extensor lag at the PIP (see image)
• Continue extension splinting for night time to compensate for all the flexion activities and postures during the day to protect the Central Slip from stretching; yielding an extensor lag.
• At week 8, progress to full unrestricted AROM and PROM of fingers, thumb and wrist while. 
• At week 8-10, initiate light strengthening as tolerated with no pain and to patients’ comfort as they progress (gripper, putty, clips, dowel grasps, towel wringing, etc).

When Applicable:

• Education the patient to limit heavy strengthening tasks, lifting and heavy use until 10 weeks post-op
• Encourage finger food tasks, in hand manipulation and coin stacking, and palm scratch exercises to optimize AROM and function.
• Encourage towel wringing exercises for incorporating fingers and wrist into HEP and functional re-integration.
• When available, find a Certified Hand Therapist to provide additional splinting

*Wound healing may be prolonged in diabetic patients and smokers

• Adhesions
• Chronic swelling
• Flexion contracture
• Grip weakening
• Mobility impairment
• Redislocation and subluxation
• Stiffness
• Swan-neck deformity

• Surgery may not fully correct the deformity or lead to an extension contracture.
• Appearance may still be somewhat less than normal secondary to persistent flexion contracture

• Carefully assess the initial mechanism of injury, because central slip disruption requires splinting of the PIP joint in full extension. If splinting is done with the PIP joint slightly flexed, boutonniére deformity will result.
• The “boxer’s knuckle” is a closed tendon injury that involves the sagittal bands at the MP joint level
• In open injuries, the tendon may come together with splinting but open repair and splinting are usually indicated. 
• Hand therapy may be critical to achieving full use of the affected finger.
• Positive Elson test indicates a central slip injury
• Patients with tenderness at the central slip insertion site who can not fully extend the finger at the PIP joint against mild resistance should be consider to have an acute central slip injury until proven otherwise.

New Articles

1. Sood A, Kotamarti VS, Granick MS. Boutonnière deformity following volar proximal interphalangeal joint dislocation. Eplasty 2016;16:ic25. PMID: 27347279
2. American Academy of Orthopedic Surgeons. 2013. [Boutonniere deformity.] Accessed February 1, 2017 at http://orthoinfo.aaos.org/topic.cfm?topic=a00004
3. Matev I: The bountonniere deformity. The hand 1:90, 1969.

Reviews

1. Griffin M, Hindocha S, Jordan D, et al. Management of extensor tendon injuries. Open Orthop J 2012;6:36-42. PMID: 22431949
2. Schöffl V, Heid A, Küpper T. Tendon injuries of the hand. World J Orthop 2012;3(6):62-9. PMID: 22720265

Classics

1. Bolton H. Tendon injuries of the wrist and hand. Postgrad Med J 1964;40:262-5. PMID: 14145044
2. 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):229-31. PMID: 3958008
3. Kontor JA. Extensor tendon injuries and repairs in the hand. Can Fam Physician 1982;28:1159-63. PMID:
4. Matev I: The bountonniere deformity. The hand 1:90, 1969.

HAND THERAPY REFERENCES

 Cannon, et al. (2001).  Diagnosis and Treatment Manual for Physicians and Therapists, Upper extremity Rehabilitation (4^th ed).  The Hand Rehabilitation Center of Indiana.

 Mackin, Callahan, Skirven, Schneider, and Osterman, (2002). Rehabilitation of the Hand and Upper Extremity, 1, (5^th ed). St Louis, MO: Mosby Year Book, Inc.

Cooper, (2014). Fundamentals of Hand Therapy; Clinical Reasoning and Treatment Guidelines for Common Diagnoses of the Upper Extremity, (2^nd ed). Mosby, imprint of Elsevier Inc.

Stanley and Tribuzi. (1992).  Concepts in Hand Rehabilitation.  F. A. Davis Company