Rheumatoid Forefoot Reconstruction

Surgical Indications

Absolute Indications

• Failed conservative management after at least 6 months of appropriate footwear modification, custom orthoses, orthopaedic shoes, and optimised medical management (DMARDs and biologics)
• Intractable plantar metatarsalgia with painful callosities beneath dislocated or subluxated lesser MTP joints causing significant functional limitation
• Severe hallux valgus deformity with first MTP joint destruction (radiographic joint space loss, erosions, subluxation) producing pain unresponsive to shoe modification
• Fixed lesser toe deformities (claw toes or hammer toes with MTP dislocation) interfering with footwear or causing ulceration

Relative Indications

• Progressive hallux valgus with early medial column collapse despite medical management
• Lesser MTP joint synovitis with dorsal subluxation but not yet fully dislocated — surgical correction before fixed dislocation yields better outcomes
• Patient preference for surgical reconstruction to enable return to enclosed footwear and improve mobility
• Painful callosities with recurrence despite regular podiatric care

Contraindications

Absolute:

• Active infection of the foot or systemic sepsis
• Inadequate soft tissue envelope (skin ulceration, active rheumatoid vasculitis)
• Critical ischaemia: absent pedal pulses not restorable by vascular intervention
• Medical unfitness for anaesthesia or prolonged rehabilitation

Relative:

• Poor bone stock with severe osteopenia or fractures through osteoporotic metatarsals (consider staged surgery)
• Active rheumatoid flare — optimise medical management before elective surgery
• Non-compliance with non-weight-bearing restrictions or post-operative rehabilitation
• Non-ambulatory or bedbound patient (conservative management preferred)

Pathophysiology of the Rheumatoid Forefoot

The Cascade of Deformity

• Synovitis of the MTP joints is the initiating event — pannus formation erodes the articular cartilage, distends the joint capsule, and destroys the collateral ligaments and plantar plate
• Volar plate attenuation allows the proximal phalanx to subluxate dorsally; the extensor tendons (previously dorsal) migrate into a subluxated dorsal-lateral position, reinforcing the deformity
• MTP dorsal subluxation progresses to dislocation — the proximal phalanx rides dorsally over the metatarsal head, the plantar fat pad is dragged distally with it, and the metatarsal head becomes exposed to direct plantar pressure
• Metatarsal head prominence beneath the thinned plantar fat pad produces intractable plantar keratoses, metatarsalgia, and pain
• Claw toe deformity: the intrinsic muscles lose their stabilising function at the MTP joint (interossei and lumbricals act as MTP flexors and IP extensors), so as the MTP extends, the IP joints flex, producing the classic claw toe posture (MTP extension, PIP flexion, DIP flexion)
• Hallux valgus of the first ray is driven by MTP synovitis and medial capsular failure, producing lateral deviation of the hallux and medial prominence of the metatarsal head
• First ray instability (loss of first-ray weight-bearing) transfers load to the lesser metatarsals, worsening the metatarsalgia cycle

Evidence for Non-Operative Management

Conservative Treatment Options

• Footwear modification: wide toe-box, rocker-bottom sole, soft upper, minimal heel height — effective early in the disease course but insufficient once fixed deformity develops
• Custom moulded orthoses: metatarsal dome or bar to offload prominent metatarsal heads; accommodative insoles with total contact design
• Medical management optimisation: coordinate with rheumatology to ensure the patient is on the most appropriate DMARD/biologic regimen; ongoing synovitis in the forefoot while on maximum medical therapy supports earlier surgical referral
• Podiatric care: regular debridement of callus, padding, and monitoring for ulceration in patients with vascular compromise or neuropathy
• Intra-articular corticosteroid injection: temporary symptom relief for acute MTP synovitis flares, but repeated injection provides diminishing returns and does not correct structural deformity

Evidence for Surgery

First MTP Arthrodesis vs Keller Arthroplasty

First MTP arthrodesis is now the gold standard for rheumatoid hallux valgus in ambulatory patients:

• Provides a stable, plantigrade medial column that bears weight normally
• Corrects the hallux valgus deformity at the joint level, eliminating the bunion prominence
• Offloads the lesser metatarsals by restoring first-ray function
• Long-term studies report sustained pain relief and functional improvement in 85-95% of patients
• Nonunion rate 5-10%; risk increased by smoking, poor bone stock, and excessive resection

Keller excision arthroplasty is reserved for elderly, low-demand, or non-ambulatory patients:

• Resection of the metatarsal head and the proximal half of the proximal phalanx
• Reliable pain relief but produces a shortened, weak hallux with loss of push-off power
• Transfer metatarsalgia is common (15-30%) because the first ray no longer bears its share of load
• Risk of hallux malleus (floppy hallux), cock-up deformity, and progressive lesser toe overload

Hoffmann Procedure vs Weil Osteotomy for Lesser Rays

Hoffmann procedure (metatarsal head resection):

• Excision of the lesser metatarsal heads through a dorsal approach
• Relieves plantar pressure by removing the bony prominence
• Simple, reliable, quick — particularly suited to multiple dislocated MTP joints in advanced disease
• Risk of transfer metatarsalgia from uneven resection; loss of the MTP joint with no articulating surface
• Long-standing standard for the severely deformed rheumatoid forefoot

Weil shortening osteotomy:

• Dorsal oblique osteotomy of the metatarsal neck with dorsal translation of the capital fragment
• Preserves the MTP joint articular surface — preferred for lesser MTP joints that are subluxated but not fully dislocated
• More technically demanding; requires precise osteotomy angle, controlled translation, and fixation
• Risk of avascular necrosis of the capital fragment (2-10%), stiffness, floating toe, and over-shortening
• Growing evidence supporting Weil osteotomy over Hoffmann in less severe disease, but Hoffmann remains appropriate for advanced dislocation

Key Evidence

First Metatarsophalangeal Joint

Articular Surfaces

• Metatarsal head: convex, broader medially than laterally, with medial and lateral sesamoid grooves on the plantar surface. The articular surface extends further plantarly than dorsally.
• Proximal phalanx base: concave, with a central ridge corresponding to the metatarsal head contour. The collateral ligaments attach to the medial and lateral tubercles of the proximal phalanx base.
• Sesamoid complex: two sesamoids (medial/tibial and lateral/fibular) within the flexor hallucis brevis tendons, articulating with the metatarsal sesamoid grooves. They act as a plantar fulcrum and weight-bearing surface. The intersesamoid ligament and the ligaments to the proximal phalanx form the sesamoid apparatus — must be preserved during arthrodesis preparation.

Capsule and Ligaments

• Medial collateral ligament: thick, strong, primary restraint to hallux valgus; attenuated or ruptured in rheumatoid hallux valgus
• Lateral collateral ligament: tighter in hallux valgus as the toe deviates laterally; contracts over time
• Plantar plate: thick fibrocartilaginous structure inserting into the proximal phalanx base; critical for MTP joint stability — ruptured or attenuated in rheumatoid disease
• Adductor hallucis: oblique and transverse heads insert onto the lateral sesamoid and proximal phalanx — a deforming force in hallux valgus, releases during arthrodesis

Neurovascular Structures at Risk

• Dorsalis pedis artery: runs in the EHL/EDL interval; crosses the first MTP joint dorsally; protect during dorsomedial approach
• Deep peroneal nerve: lateral to the dorsalis pedis artery at this level; supplies first webspace sensation
• Medial dorsal cutaneous nerve: branch of the superficial peroneal nerve, crosses the first MTP region medially — injury produces numbness along the medial hallux

Lesser Metatarsophalangeal Joints (Second to Fifth)

Metatarsal Cascade (Parabola)

• The metatarsals form a harmonious parabola on the lateral weight-bearing radiograph: the second metatarsal is longest, followed by the first, then a gradual symmetric decline to the fifth
• This parabola distributes plantar pressure evenly across the forefoot
• Rheumatoid deformity disrupts the parabola: dorsal subluxation of MTP joints, plantar displacement of the fat pad, and variable metatarsal head erosion produce uneven lengths and focal pressure

Lesser MTP Joint Structures

• Metatarsal head: convex, smaller than the first, receives 25-50% of forefoot load depending on the position in the parabola
• Collateral ligaments: primary stabilisers of the MTP joint; destroyed by pannus in rheumatoid disease, allowing dorsal subluxation
• Plantar plate: inserts into the proximal phalanx base; the key stabiliser against dorsal subluxation — once ruptured, the extensor tendons pull the toe dorsally
• Extensor tendons (EDL, EDB): normally dorsal-centred; subluxate dorsolaterally in rheumatoid deformity, reinforcing the claw toe posture
• Flexor tendons (FDL, FDB): plantar to the MTP joint; the FDL pull at the IP joints produces the flexion component of claw toe deformity once the intrinsic stabilisers fail

Dorsal Approach Anatomy

• Extensor digitorum longus tendons: run directly over the lesser MTP joints dorsally; retracted for exposure
• Extensor digitorum brevis tendons: lie deep to EDL, converge on the lateral aspect of the extensor hood
• Dorsalis pedis artery and deep peroneal nerve: in the first-second intermetatarsal space; must be identified before the dorsal longitudinal or transverse incision for lesser metatarsal surgery
• Dorsal venous network: prominent over the MTP joints; ligate or cauterise during dissection to maintain a dry field

Plantar Structures

Plantar Fat Pad

• A specialised fibrofatty pad beneath the metatarsal heads, held in place by the plantar aponeurosis septa
• In rheumatoid disease, the fat pad is displaced distally as the MTP joints dislocate dorsally — the metatarsal heads lose their cushioning
• This displacement is progressive and irreversible — reconstruction repositions the bone but does not fully restore the fat pad to its original position

Neurovascular Structures on the Plantar Surface

• Plantar digital nerves (branches of the medial and lateral plantar nerves): run between the metatarsal heads towards the toes; at risk during plantar incisions (rarely used in rheumatoid forefoot surgery)
• Plantar digital arteries: accompany the nerves; the tenuous vascularity of the rheumatoid toe is a concern during lesser ray surgery — aggressive handling, K-wire placement, or excessive shortening can compromise distal perfusion

Cervical Spine — Critical Pre-anaesthetic Anatomy

Atlantoaxial and Subaxial Instability

• Transverse ligament: primary restraint to anterior translation of C1 on C2; destroyed by rheumatoid pannus in up to 30% of patients
• Pannus formation: granulomatous tissue from the odontoid peg can compress the spinal cord, producing myelopathy, quadriparesis, or sudden death during neck extension at intubation
• Subaxial subluxation: multiple levels below C2 can subluxate; neck extension narrows the spinal canal at each level
• Basilar invagination: upward migration of the odontoid through the foramen magnum; detectable on lateral cervical radiograph as the odontoid tip lying above McGregor's line

Radiographic Assessment

Weight-Bearing Radiographs (Mandatory)

• Anteroposterior (AP) view: assess hallux valgus angle (HVA), intermetatarsal angle (IMA), metatarsal parabola, metatarsal head erosion and cysts, lesser MTP subluxation/dislocation
• Lateral view: assess dorsiflexion angle of the first ray, sesamoid position, dorsal subluxation of lesser MTP joints, metatarsal head descent
• Oblique view: visualises the lateral metatarsal heads and intermetatarsal joints for erosions and cysts

Key Measurements

• Hallux valgus angle (HVA): angle between the longitudinal axis of the first metatarsal and the proximal phalanx; pathological when greater than 15-20 degrees
• Intermetatarsal angle (IMA): angle between the first and second metatarsal shafts; pathological when greater than 9-10 degrees
• MTP subluxation: measured as the percentage of the proximal phalanx base dorsal to the metatarsal head; dislocation when subluxation is greater than 75%

Positioning and Preparation

Patient position: Supine on the operating table with a sandbag beneath the ipsilateral buttock to internally rotate the foot into a neutral or slight valgus position. The foot rests at the end of the table or on a padded foot platform. Place a non-sterile thigh or calf tourniquet — calf tourniquet is preferred for bilateral forefoot surgery to allow access to both feet without repositioning.

Anaesthesia: Regional anaesthesia (spinal or popliteal sciatic block with ankle block) is strongly preferred over general anaesthesia to avoid cervical spine risks during intubation. If general anaesthesia is unavoidable, cervical spine flexion-extension radiographs must have been reviewed and intubation performed with awake fibreoptic technique and cervical precautions.

Antibiotic prophylaxis: Single dose of intravenous cefazolin (or clindamycin if penicillin-allergic) at induction. Redose if tourniquet time exceeds 4 hours. Consider additional prophylaxis in immunosuppressed patients.

Tourniquet: Inflated to 250 mmHg (calf) or 300 mmHg (thigh). Maximum tourniquet time 2 hours. Exsanguinate the limb with an Esmarch bandage before inflation.

Consent: Specifically counsel regarding nonunion of the first MTP fusion (5-10%), transfer metatarsalgia (5-15%), wound infection (2-5% in immunosuppressed), prolonged swelling (3-6 months common), vascular compromise of the lesser toes, and the possibility of subsequent procedures for recurrent or residual deformity.

First MTP Arthrodesis — Step-by-Step (Dorsomedial Approach)

Step 1: Incision

Make a dorsomedial longitudinal incision 5-8 cm centred over the first MTP joint, slightly medial to the EHL tendon. Incise skin sharply and deepen through subcutaneous tissue.

Step 2: Capsular Exposure

Incise the dorsal joint capsule longitudinally in line with the incision. Retract the capsule and extensor hallucis brevis (EHB) tendon. Expose the dorsolateral eminence of the metatarsal head and the dorsal surface of the proximal phalanx base. Release the contracted lateral collateral ligament and the adductor hallucis insertion on the lateral sesamoid complex to mobilise the hallux into valgus correction.

Step 3: Articular Surface Preparation

Using a flat oscillating saw, resect the metatarsal head articular surface in a concave pattern to match the convex surface of the proximal phalanx base. Resect the proximal phalanx base articular surface flat or slightly convex. The resection should be minimal — enough to remove the eroded cartilage and expose bleeding subchondral bone without creating a significant bone gap. Avoid excessive resection which risks nonunion by leaving insufficient bone contact.

Step 4: Reduction and Positioning

Reduce the joint with the hallux positioned at 15 degrees valgus, 10-15 degrees dorsiflexion relative to the floor (not the metatarsal shaft), and neutral rotation. Check that the plantar surface of the hallux rests flush with the floor in the weight-bearing position. The intermetatarsal angle should be corrected to less than 5 degrees. Use temporary K-wires or reduction clamps to hold the position.

Step 5: Fixation

Apply a pre-contoured dorsal plate (low-profile titanium, 2.4 mm or 2.7 mm) spanning the fusion site. Secure with 3-4 screws proximal and 2-3 screws distal into the proximal phalanx. Add an interfragmentary lag screw (3.5 mm or 4.0 mm) from dorsal-proximal to plantar-distal across the fusion site for compression. Alternatively, use crossed screws or a plate-only construct. Ensure the plate sits flush on the dorsal cortex without prominence — a prominent dorsal plate causes shoe irritation and may require later removal.

Step 6: Wound Closure

Irrigate the wound thoroughly. Close the dorsal capsule with absorbable suture (2-0 Vicryl). Close subcutaneous tissue with 3-0 Vicryl. Close skin with interrupted 3-0 nylon. Apply a sterile wool and crepe dressing and a below-knee plaster back-slab or a rigid surgical shoe.

Lesser Metatarsal Surgery — Step-by-Step

Approach Selection

• Hoffmann procedure: suitable for dislocated or severely destroyed lesser MTP joints where preservation of the articular surface is not feasible
• Weil osteotomy: suitable for subluxated but reducible lesser MTP joints where the articular surface can be preserved

Dorsal Approach to the Lesser MTP Joints

Make two dorsal longitudinal incisions (one over the second and third MTP joints, a second over the fourth and fifth) or a single transverse dorsal incision over all four lesser MTP joints. Longitudinal incisions between the second and third and between the fourth and fifth rays minimise dorsal wound problems.

Hoffmann Procedure (Metatarsal Head Resection)

Step 7: Expose the Metatarsal Head

Incise the dorsal MTP capsule and retract the extensor tendons. Dislocate the proximal phalanx dorsally to expose the metatarsal head.

Step 8: Resect the Metatarsal Head

Resect the metatarsal head through the metatarsal neck with an oscillating saw. Resect a consistent amount across all lesser rays — typically 4-6 mm of the metatarsal head, measured from the distal end of the metatarsal neck. The resection must be perpendicular to the metatarsal shaft axis. Round the cut edge with a rongeur to remove any sharp edges that could irritate the plantar soft tissues.

Weil Shortening Osteotomy

Step 7: Expose the Metatarsal Neck

Incise the dorsal MTP capsule longitudinally. Retract the extensor tendons. Expose the dorsal surface of the metatarsal neck.

Step 8: Osteotomy

Using a micro-oscillating saw, make an oblique osteotomy of the metatarsal neck from distal-dorsal to proximal-plantar at approximately 20-30 degrees to the metatarsal shaft axis. Start the osteotomy 1-2 mm distal to the metatarsal neck condyles. The osteotomy should exit the plantar cortex 3-4 mm proximal to the dorsal start point.

Step 9: Dorsal Translation

Shift the capital fragment (head and distal neck) proximally (dorsally) along the osteotomy plane by 4-6 mm, depending on the degree of shortening required. Translate the same amount at each ray to preserve the metatarsal parabola.

Step 10: Fixation

Fix the capital fragment to the metatarsal shaft with one or two 2.0 mm screws from dorsal to plantar. Ensure screws engage the plantar cortex of the capital fragment. Resect the dorsal spike (the proximal dorsal edge of the metatarsal shaft that is now prominent) with the saw to prevent impingement on the extensor mechanism.

Claw Toe Correction

When Is Claw Toe Correction Required?

Claw toes (MTP extension, PIP flexion, DIP flexion) are invariably present with rheumatoid forefoot deformity. After correcting the MTP joint, the claw toe posture may partially correct but usually requires a separate procedure on the IP joints.

Step 11: PIP Joint Release or Arthroplasty

For flexible claw toes: release the extensor mechanism over the PIP joint and perform a percutaneous flexor tenotomy (FDS and FDP) at the base of the proximal phalanx to allow the PIP joint to extend.

For fixed claw toes: perform a PIP joint resection arthroplasty (excise the head of the proximal phalanx through a dorsal or lateral incision) and stabilise with a 0.8 mm or 0.9 mm K-wire driven longitudinally across the MTP and IP joints, maintaining the toe in a corrected position for 4-6 weeks.

Step 12: Flexor-to-Extensor Tendon Transfer (Girdlestone-Taylor)

In selected cases where the MTP joint remains unstable after metatarsal surgery, transfer the long flexor tendon (FHL or FDL split) to the extensor expansion at the proximal phalanx to provide active MTP flexion and correct the extensor overpull.

Final Wound Closure and Dressing

Step 13-15: Closure and Dressing

• Irrigate all wounds thoroughly with normal saline
• Close dorsal MTP capsules with 2-0 Vicryl where possible
• Close subcutaneous tissue with 3-0 Vicryl
• Close skin with 3-0 nylon interrupted sutures
• Apply non-adherent dressings (Jelonet) to each incision
• Apply a bulky wool and crepe dressing with the foot in a neutral to slight equinus position
• Apply a below-knee plaster back-slab or a rigid postoperative surgical shoe
• Check capillary refill of all lesser toes before leaving theatre — prolonged tourniquet time and aggressive correction can compromise toe perfusion

Post-operative Protocol

Immediate Phase (Day 0-14)

• Immobilisation: Below-knee non-weight-bearing cast or rigid surgical shoe with crutches — strictly non-weight-bearing on the operated foot for the first 2-6 weeks depending on fixation stability and bone quality
• Elevation: Elevate the foot above heart level for the first 48-72 hours to reduce oedema, which is typically severe in rheumatoid patients
• Dressing: Initial bulky wool and crepe dressing for 48 hours; then a lighter dressing at the first wound check at 7-10 days
• K-wire care: If K-wires are in situ for toe correction, pin-site dressings changed twice weekly; avoid soaking; pins remain for 4-6 weeks
• Analgesia: Multimodal — paracetamol, NSAIDs (if renal function permits), and opioids for the first 48-72 hours; nerve block (popliteal) provides effective post-operative analgesia for 12-18 hours

###中期 Phase (Weeks 2-6)

• Weeks 2-6: Continue non-weight-bearing in a below-knee cast boot. Check wound at 2 weeks for suture removal and signs of infection.
• Radiographic check: At 6 weeks, weight-bearing AP and lateral radiographs to assess early consolidation at the first MTP fusion and position of the lesser metatarsal surgery.

Late Phase (Weeks 6-12)

• Weeks 6-12: Begin progressive weight-bearing in a below-knee cast boot or rigid shoe as consolidation allows. Range-of-motion exercises for the lesser MTP joints.
• At 8-12 weeks: If early consolidation is evident radiographically, transition to a wide, supportive shoe. Formal physiotherapy for gait re-education, proprioception, and scar management.

Long-term (3-12 Months)

• Full recovery: 6-12 months for complete healing, resolution of oedema, and functional adaptation. Rheumatoid patients often have persistent mild forefoot swelling for 6-9 months.
• Footwear: Wide, deep toe-box, soft leather, rocker-bottom sole. Orthopaedic shoes may be required permanently in patients with residual deformity or multiple joint involvement.
• Orthoses: Custom moulded insoles with metatarsal support, accommodative for any residual prominences.

Perioperative Immunosuppression Management

DMARDs — Continue or Hold?

Current evidence supports continuing methotrexate perioperatively in most patients undergoing orthopaedic surgery. Withholding methotrexate is associated with increased disease flare and does not clearly reduce wound complications.

Leflunomide, sulfasalazine, hydroxychloroquine: generally continued perioperatively; low wound complication risk.

Biologic agents (TNF inhibitors, rituximab, tocilizumab, abatacept, JAK inhibitors): hold perioperatively in coordination with rheumatology. TNF inhibitors are typically held for 2-3 half-lives before surgery; rituximab has a prolonged effect and timing must be individualised.

Wound Healing in the Rheumatoid Patient

• Skin: thin, atrophic from chronic steroid use; poor vascularity; slow healing
• Soft tissues: reduced collagen synthesis and fibroblast activity; delayed tensile strength
• Infection risk: 2-5% overall, higher in patients on biologics, long-term steroids, or with concurrent diabetes
• Practical measures: meticulous haemostasis, minimal skin undermining, longitudinal incisions (avoid transverse incisions where possible), antibiotic prophylaxis, delayed suture removal (14-18 days), close wound surveillance

Special Case: Cervical Spine Instability

Why This Matters for Forefoot Surgery

Rheumatoid arthritis affects the cervical spine in a significant proportion of patients. Atlantoaxial subluxation, subaxial subluxation, and basilar invagination can compress the cervical cord during neck extension at intubation, producing quadriplegia or death.

Pre-operative Assessment

• Flexion-extension cervical spine radiographs are mandatory before any procedure under general anaesthesia in a patient with rheumatoid arthritis
• Measure the anterior atlantodens interval (AADI) — greater than 3 mm is abnormal, greater than 9 mm is a relative contraindication to intubation without precautions
• MRI of the cervical spine if there are neurological symptoms (myelopathy, paraesthesia, gait disturbance) or if flexion-extension radiographs show significant instability

Practical Implications

• Regional anaesthesia is preferred: spinal, epidural, or popliteal block with ankle block avoids the cervical spine entirely
• If general anaesthesia is unavoidable: awake fibreoptic intubation with cervical spine precautions (manual in-line stabilisation, no neck extension)
• Never assume someone else has checked — in the exam, always state that you would personally confirm cervical spine imaging before proceeding

Special Case: Bilateral Forefoot Reconstruction

Staging

• One-stage bilateral: possible under regional anaesthesia (bilateral popliteal blocks); saves total anaesthetic exposure and hospital admission time; non-weight-bearing on both feet requires a wheelchair or bilateral heel-touch walking frame for 6 weeks
• Two-stage: 6-12 weeks apart; allows one foot to weight-bear before the second surgery; preferred in patients with significant medical comorbidities or poor balance

Practical Considerations

• Non-weight-bearing on both feet is extremely demanding — assess the patient's home environment, support network, and upper limb strength before planning simultaneous surgery
• Wheelchair or mobility scooter may be required for 6 weeks post-operatively
• The patient must be able to perform transfers, self-care, and household tasks while non-weight-bearing bilaterally