Boutonnière Deformity — Reconstruction

Surgical Indications

Absolute Indications

• Open Zone III extensor tendon injury with loss of active PIP extension — primary repair within 24 hours
• Bony avulsion of central slip with greater than 2 mm fragment displacement and articular incongruity — ORIF or reattachment
• Failed non-operative management — persistent or recurrent deformity after 6-8 weeks of compliant full-time PIP extension splinting
• Chronic boutonnière (greater than 12 weeks) with supple PIP (passive extension to 0 degrees) and functional disability

Relative Indications

• Patient dissatisfaction with functional or cosmetic appearance after closed treatment
• Inflammatory arthropathy (rheumatoid, psoriatic) with persistent deformity despite optimal medical management
• Recurrent deformity after previous surgical reconstruction
• Concomitant nerve or vascular injury requiring exploration

Contraindications

Absolute:

• Fixed PIP flexion contracture (passive extension cannot reach 0 degrees) — must be corrected first
• Active infection, poorly controlled wound
• Non-compliant patient or inability to participate in structured hand therapy (relative absolute)

Relative:

• Mild deformity (less than 30 degrees PIP flexion) with minimal functional limitation — try closed treatment
• Elderly or low-demand patient with comfortable, functional range — may choose observation
• Severe rheumatoid synovitis not medically optimised — treat the synovitis first

Evidence for Non-Operative Treatment

PIP Extension Splinting for Acute Closed Injuries

• Full-time PIP extension splinting for 6 consecutive weeks, with the DIP left completely free, is the standard of care for acute closed central-slip injuries
• The splint is removed only for wound care and supervised active DIP flexion exercises
• The mechanism of action is mechanical: DIP flexion pulls the lateral bands dorsally across the PIP joint, stretching the ORL and allowing the extensor mechanism to heal with the central slip in correct anatomical position
• Reported success rates in compliant patients: 80-90% excellent/good outcomes for acute (less than 2 week) closed injuries treated with full-time splinting (Evans, Green)

Key Evidence (Closed Treatment)

• Evans (2006) — detailed the "splint the PIP, mobilise the DIP" protocol; approximately 90% good results in acute closed boutonnière when compliance is assured
• Coons and Green (2001) — retrospective series confirming that early full-time PIP extension splinting with DIP exercises is the most reliable closed treatment; outcomes deteriorate if initiation of splinting is delayed beyond 2 weeks

Evidence for Surgery

Timing and Case Selection

• For established chronic boutonnière (greater than 12 weeks) with failed closed treatment, multiple surgical options exist but the evidence base is largely Level IV (case series) with no high-quality comparative trials
• The key principle consistent across all series: the outcome of reconstruction is determined more by patient selection and post-operative rehabilitation than by the specific surgical technique chosen
• A supple PIP with passive extension to 0 degrees is the single most important predictor of a successful outcome

Key Evidence

The Extensor Mechanism at the PIP Joint (Zone III)

Central Slip — Anatomy and Function

• The central slip is the continuation of the common extensor tendon (EDC in fingers, EIP/index, EDM/small) that inserts on the dorsal base of the middle phalanx
• It is the primary active extensor of the PIP joint — it provides roughly 80% of PIP extension power
• The central slip is a flat, broad tendon approximately 4-6 mm wide at the PIP level, receiving contributions from the interosseous and lumbrical muscles via the lateral bands
• The dorsal capsule of the PIP joint lies immediately deep to the central slip — injury to the central slip frequently involves the dorsal capsule, and the two structures should be repaired together

Lateral Bands — Normal and Pathological Position

Normal anatomy:

• The two lateral bands (radial and ulnar) run dorsal to the PIP axis of rotation in the uninjured digit
• Each lateral band receives: fibres from the interosseous muscle (on its respective side), the lumbrical (radial side only, in the index to little fingers), and contributions from the extensor tendon
• Distal to the PIP, the lateral bands converge to form the terminal tendon, which inserts on the dorsal base of the distal phalanx

Pathological migration in boutonnière deformity:

• When the central slip is disrupted, the lateral bands lose their dorsal restraint and migrate volarly — they slide past the PIP axis of rotation
• Once volar to the PIP axis, the lateral bands become flexors of the PIP joint — each contraction of the intrinsic muscles (which are meant to extend the PIP via the lateral bands) now increases the PIP flexion deformity
• The volar migration also tethers the oblique retinacular ligament, which contributes to DIP hyperextension

Oblique Retinacular Ligament (ORL, Landsmeer's Ligament)

• The ORL is a slender, oblique ligament that runs from the volar aspect of the flexor tendon sheath at the proximal phalanx level to the dorsal aspect of the lateral bands or terminal tendon distally
• In the uninjured finger, the ORL acts as a passive coupling between PIP and DIP motion: when the PIP extends, the ORL slackens — when the PIP flexes, the ORL tightens and helps flex the DIP
• In boutonnière deformity, the ORL becomes pathologically tight because the lateral bands are volarly displaced — this pulls the terminal tendon into extension and contributes to the DIP hyperextension
• DIP hyperextension in boutonnière is therefore a passive mechanical phenomenon (from ORL tightness) rather than an active one

The Transverse Retinacular Ligament (TRL)

• Also known as the Cleland's ligament in its oblique part, the TRL runs transversely from the lateral band to the flexor tendon sheath at the PIP level
• It is one of the structures that normally holds the lateral bands in a dorsal position
• Disruption or attenuation of the TRL is thought to contribute to volar lateral-band migration in boutonnière deformity
• Some surgical techniques incorporate TRL reefing to help restore lateral-band position

Zones of the Extensor Mechanism

The Verdan classification divides the extensor tendon into 8 zones (odd = joint, even = bone):

Vascular Anatomy and Wound Healing

• The dorsal skin over the PIP joint has a segmental blood supply from the dorsal digital branches of the radial and ulnar digital arteries
• The central slip itself is relatively hypovascular — this is why it has limited healing potential and requires prolonged protection after repair
• The lateral bands are better vascularised (intrinsic muscle contributions) — this makes them a good choice for local transfer (Matev) in chronic cases, as they bring their own blood supply into the reconstruction

Structures at Risk During Surgical Exposure

• Dorsal digital nerves — small-calibre sensory branches of the radial nerve (index, middle, ring radial) and ulnar nerve (ring ulnar, small) that run in the dorsal subcutaneous tissue over the PIP — they can be divided during skin incision if the incision is placed too laterally or dorsally
• The extensor tendon itself (the repaired/reconstructed structure) — the most common "injured" structure is the repair itself, by overly aggressive post-operative mobilisation
• The articular surface of the PIP joint — the joint is entered during dorsal capsulectomy or bony preparation for central-slip reattachment; inadvertent chondral injury must be avoided
• The opposite-side lateral band — during Matev transfer, the intact lateral band must be protected from iatrogenic injury, as both bands are needed for balanced PIP function

Positioning and Preparation

Patient position: Supine, arm abducted on a hand table. A well-padded tourniquet is applied to the upper arm (or forearm for better comfort: 200 mmHg). Exsanguinate with an Esmarch bandage.

Anaesthesia: Regional anaesthesia (supraclavicular or infraclavicular brachial plexus block) with sedation — this provides excellent muscle relaxation and a bloodless field while allowing the patient to tolerate tourniquet times of 60-90 minutes. WALANT is not ideal for complex reconstructions because the patient may move during delicate steps, but can be used in selected patients.

Consent: Specifically counsel regarding risk of recurrence (approximately 15% at 5 years), residual stiffness (flexion loss of 10-20 degrees common), swan-neck conversion (overcorrection), DIP extension lag (if Fowler tenotomy added), infection (less than 1%), and need for prolonged therapy compliance.

Approach

Dorsal Approach to the PIP Joint

The standard approach is a dorsal curvilinear or lazy-S incision centred over the PIP joint:

1. A 3-4 cm dorsal longitudinal incision is made centred over the PIP joint, gently curving to avoid crossing the joint crease at 90 degrees (which can cause hypertrophic scarring)
2. Alternatively, a midaxial approach (midline of the finger on the ulnar or radial border) can be used — this gives access to the dorsal structures through a laterally based flap and avoids the dorsal scar
3. Elevate skin flaps carefully in the subcutaneous plane, protecting the dorsal sensory nerves

Surface landmark: The PIP joint line is identified by flexing and extending the finger — the centre of rotation lies at the level of the PIP flexion crease, midpoint between the proximal and middle phalanges.

Deep Dissection

1. Identify the extensor mechanism — in established boutonnière, the central slip is attenuated or discontinuous, and the lateral bands are visible in their volarly displaced position
2. The attenuated central slip may appear as a thin, scarred sheet rather than a discrete tendon
3. Enter the PIP joint through the dorsal capsule (which is often disrupted alongside the central slip) to assess the articular surfaces — if cartilage loss is severe (greater than 50%), consider salvage options (PIP arthrodesis or arthroplasty) rather than reconstruction
4. Identify the lateral bands and mobilise them gently from their volar position back to the dorsal aspect of the PIP joint — use a fine elevator to separate them from the underlying capsule and collateral ligaments

Prerequisites Satisfied — Intraoperative Check

Before proceeding to any specific reconstruction, confirm:

• The PIP joint can be passively extended to 0 degrees — if not, perform a dorsal capsulectomy and release of the accessory collateral ligaments
• The articular surface is in satisfactory condition (less than 50% cartilage loss)
• The lateral bands are of adequate quality for transfer if a Matev procedure is planned
• At least one lateral band can be mobilised without disrupting the contralateral band

Central-Slip Repair (Acute or Repairable Chronic)

Indication

The central slip is identifiable and can be advanced to its insertion without excessive tension (gap less than 5 mm with the PIP in 20 degrees of flexion).

Technique

1. Prepare the insertion site: Expose the dorsal base of the middle phalanx. If a bony fragment is present, mobilise it with care. If the tendon end is soft tissue only, freshen the footprint to bleeding bone with a small curette or rongeur
2. Suture repair: Use a 3-0 braided polyester (Ethibond) or 4-0 braided polyester suture in a modified Kessler or Bunnell configuration, depending on tendon integrity:
   • Good-quality tendon: Modified Kessler with epitendinous repair
   • Poor-quality/attenuated tendon: Multiple figure-of-eight sutures to spread the tension across a wider area; consider augmentation with a lateral-band slip
3. Fixation to bone:
   • Bony avulsion fragment larger than 2 mm: reduce and fix with a 1.3 mm or 1.5 mm mini-screw or K-wire
   • Soft-tissue reattachment: Drill two 1.1 mm transosseous tunnels from the dorsal footprint to the volar cortex of the middle phalanx base; pass the suture ends through the tunnels and tension over a button on the volar aspect (tension the repair in 20 degrees of PIP flexion)
4. Suture anchor alternative: A 1.3 mm or 1.8 mm suture anchor loaded with 3-0 braided polyester can be placed in the dorsal base of the middle phalanx as an alternative to transosseous tunnels — this is simpler but may not achieve equivalent pull-out strength in early active motion protocols

Tensioning

• Tie the repair with the PIP joint in 20-30 degrees of flexion — do NOT tension in full extension, as this will produce a swan-neck deformity
• The repair should be snug but not tight — the PIP should still passively flex to at least 70 degrees
• The lateral bands should sit dorsal to the PIP axis of rotation — if they remain volar, they must be relocated

Lateral-Band Transfer (Matev Reconstruction)

Indication

Chronic boutonnière with attenuated central slip that cannot be primarily repaired (gap greater than 5 mm or poor tissue quality). A supple PIP with passive extension to 0 degrees remains an absolute prerequisite.

Principle

One lateral band is transected proximally and transferred to the dorsal base of the middle phalanx to reconstruct the central-slip insertion. The transferred lateral band then acts as an active PIP extensor while the remaining lateral band continues to provide DIP extension.

Technique (Matev)

1. Identify the lateral bands — in chronic cases they are volarly displaced and may be adherent. Mobilise them with a fine elevator, preserving the transverse retinacular ligaments where possible
2. Select the donor band: On the side of the scar (previous injury) — use the more accessible lateral band. If neither side is scarred, choose the ulnar lateral band (more robust in most digits)
3. Transect the lateral band at the level of the proximal phalanx midshaft (Zone IV) — a full-thickness cut. The proximal end will be transferred
4. Route the distal stump: The distal stump of the transected lateral band is left attached to the terminal tendon — it continues to provide DIP extension through the intact contralateral lateral band
5. Transfer the proximal end: Pass the proximal cut end of the lateral band through a transosseous tunnel drilled at the dorsal base of the middle phalanx (aim: exit volarly, just proximal to the FDP insertion, to avoid flexor tendon tethering)
6. Fixation: Tension the transferred lateral band with the PIP in 20 degrees of flexion. Suture it to itself or secure it over a volar button. Alternatively, suture the transferred band end-to-side to the contralateral lateral band after routing it through the bone tunnel
7. Checkbalance: The PIP should extend to 0 degrees passively and flex to at least 70 degrees. The DIP should still actively extend (via the intact contralateral lateral band and the terminal tendon)

Terminal-Tendon Tenotomy (Fowler)

Indication

Persistent DIP hyperextension (greater than 20 degrees) after the PIP has been corrected to neutral. The tenotomy is performed as a separate or adjunctive procedure — it can be done through the same dorsal exposure or as a percutaneous step.

Technique

1. Extend the PIP to neutral (or keep the PIP splinted in extension) to tension the terminal tendon
2. Identify the terminal tendon over the middle phalanx, approximately 3-5 mm distal to the DIP joint (NOT over the joint itself — tenotomising over the joint violates the dorsal capsule)
3. Make a transverse division of the terminal tendon through a small stab incision (percutaneous) or through the open dorsal wound
4. Confirm correction: the DIP should now have a 10-20 degree passive extension lag. The active DIP flexion should be preserved (the FDP provides DIP flexion independently)
5. Do NOT repair the tenotomy — the separation is intentional to release the ORL tether

Littler Oblique Retinacular Ligament (ORL) Reconstruction

Indication

Persistent DIP hyperextension in a young, high-demand patient where a Fowler tenotomy (which creates a permanent extension lag) is undesirable. The ORL reconstruction aims to reconstruct the Landsmeer ligament to dynamically link PIP extension with DIP flexion.

Principle

A free tendon graft (palmaris longus) is routed from the base of the proximal phalanx (volar-ulnar/radial) to the dorsal terminal tendon, parallel to the normal ORL. When the PIP extends, the graft tightens and passively flexes the DIP — restoring the natural PIPC-DIP coupling.

Technique (simplified)

1. Harvest palmaris longus tendon (or plantaris, or extensor indicis proprius if palmaris is absent)
2. Create a transosseous tunnel at the base of the proximal phalanx from volar-lateral to dorsal
3. Create a second tunnel through the terminal tendon just proximal to the DIP joint
4. Weave the graft from the volar tunnel at the proximal phalanx base, along the lateral aspect of the finger, to the terminal tendon
5. Tension with the PIP in 0 degrees and the DIP in 20 degrees of flexion
6. Secure the graft to the terminal tendon with 5-0 Prolene

This procedure is rarely performed in contemporary practice — Fowler tenotomy is simpler, more predictable, and selected in the vast majority of cases requiring DIP correction.

Closure and Dressing

1. Close the skin with 4-0 or 5-0 nylon interrupted sutures (avoid horizontal mattress sutures that can compromise dorsal skin vascularity)
2. Apply a non-adherent dressing (Jelonet)
3. Apply a PIP extension splint as part of the dressing — use a dorsal or volar thermoplastic splint that holds the PIP in full extension but leaves the DIP completely free
4. No MCP immobilisation is required unless the procedure was combined with an intrinsic release

Post-operative Rehabilitation Protocol

The rehabilitation protocol is the single most important determinant of outcome in boutonnière reconstruction. The programme below is a generic guideline — specific protocols should be tailored to the intraoperative findings, repair quality, and the hand therapist's preference.

Phase 1: Protection (Weeks 0-6)

• Continuous PIP extension splinting — the PIP is held in full extension at all times, day and night
• DIP free and actively exercised — the patient performs 10-15 active DIP flexions every waking hour using the opposite hand to block the PIP in the splint while flexing the DIP against resistance
• The DIP exercise is the treatment: each DIP flexion cycle pulls the lateral bands dorsally, stretches the ORL, and maintains the correct biomechanical environment for the central-slip reconstruction to heal
• Splint removal only for supervised wound care and therapy sessions — never remove the splint for more than 15 minutes at a time
• Wound care: Keep the dorsal incision dry; change the dressing every 3-5 days
• Suture removal: at 14 days

Phase 2: Transition (Weeks 6-8)

• The PIP extension splint is removed for supervised active PIP extension exercises — the patient actively extends the PIP against gravity (no resistance) with the DIP free
• Begin active PIP flexion within a comfortable range — typically starting at 30-40 degrees, progressing to 60 degrees by week 8
• Night splinting continues for at least 4 more weeks
• Never force passive PIP flexion — the reconstruction is weakest at weeks 4-8 and can be stretched out

Phase 3: Strengthening (Weeks 8-12)

• Progressive active PIP flexion and extension against gentle resistance (putty, elastic bands)
• Scar massage and desensitisation
• Grip strengthening begins at week 10
• Night splinting continues until week 12

Phase 4: Return to Function (Weeks 12+)

• Full active ROM expected by 12-16 weeks
• Return to heavy manual work: usually at 12-16 weeks
• Final ROM remains relatively stable after 6 months
• Patient should expect some permanent flexion loss (10-20 degrees at the PIP) in most cases

Therapy Compliance

• The single most common cause of failure in boutonnière reconstruction is loss to therapy or non-compliance with the splinting protocol
• Assess the patient's social situation, occupation, and motivation before offering reconstruction
• A written therapy contract signed by the patient is reasonable practice for complex reconstructions

Special Case: Traumatic Boutonnière (Acute, Closed)

Clinical Scenario

A patient presents within 2 weeks of a closed PIP injury with an Elson test positive for central-slip disruption. The PIP is supple with no fixed flexion deformity.

Management

1. Full-time PIP extension splinting with DIP free for 6 weeks — the standard of care
2. Follow the Phase 1 protocol described above
3. Success rate: 80-90% good/excellent with compliant splinting
4. If deformity recurs after 6 weeks of compliant splinting, consider reconstruction as for chronic boutonnière

Surgical Indication in the Acute Setting

• Open Zone III laceration — primary repair within 24 hours
• Failed closed treatment despite compliance (persistent deformity at 8 weeks)
• Bony avulsion with greater than 2 mm displacement

Special Case: Rheumatoid Boutonnière

Why It Is Different

• The pathology is synovitis-driven attenuation of the central slip and dorsal capsule, not a discrete tendon rupture
• The lateral bands are displaced volarly by hypertrophic synovium
• Bony erosions and joint destruction may coexist
• Direct repair of the attenuated central slip tissue is futile — it will stretch out

Management Algorithm

1. Optimise medical management of synovitis (DMARDs, biologics) — do not operate on an actively inflamed joint
2. If synovitis is controlled but deformity persists (supple PIP):
   • Dorsal synovectomy to decompress the PIP joint
   • Lateral-band relocation (Matev-type) without attempting direct central-slip repair
   • Fowler tenotomy if DIP hyperextension persists after PIP correction
3. If the PIP joint is destroyed (radiographic loss of greater than 50% joint space, erosions):
   • PIP arthrodesis (in 20-30 degrees of flexion for functional hand position)
   • PIP arthroplasty (silicone) in selected low-demand patients with good bone stock and intact collateral ligaments

Outcome Expectation

• Results are less predictable than traumatic boutonnière — approximately 50-70% satisfactory outcomes
• Recurrence risk is higher due to ongoing synovitis
• Managing patient expectations is critical

Special Case: Failed Primary Reconstruction

Patterns of Failure

1. Recurrence within 6 weeks = inadequate splinting or therapy non-compliance — resume full-time PIP extension splinting for another 4-6 weeks
2. Recurrence at 6-12 weeks = repair stretched out — assess passive correction; if supple, consider re-exploration and revision with augmentation (tendon graft, lateral-band transfer)
3. Recurrence after 12 weeks = established failure — assess PIP suppleness. Options: (a) revision reconstruction with palmaris longus graft if supple, (b) PIP arthrodesis if stiff or if patient has failed two prior reconstructions

Revision Strategy

• If the lateral bands are intact and the PIP is supple, a palmaris longus tendon graft woven through the base of the middle phalanx and the lateral bands can reconstruct the central slip
• If the PIP is stiff (less than 30 degrees passive extension), serial casting or dynamic splinting first, then reassess
• If all else fails or the joint is arthritic: PIP arthrodesis in 20-30 degrees of flexion — this provides a stable, pain-free finger at the cost of PIP motion