Forefoot Pathology: Hammertoes & Second Ray

EBM Forefoot Pathology: Hammertoes & Second Ray

• Week 3 focuses on hammertoes and pain sources in lesser metatarsals, excluding the 5th.
• Main sources are McGlamry's Comprehensive Textbook of Foot and Ankle Surgery (4th & 5th eds.), Foot and Ankle Radiology (2nd ed.), and Master Techniques in Podiatric Surgery: The Foot and Ankle.

Learning Objectives

• Understand the biomechanical causes of hammertoes.
• Understand the pathophysiology of Freiberg's Infarction and Pre-dislocation syndrome.
• Identify clinical and radiographic features of hammertoes and MTP joint pathology.
• Recognize physical exam findings of common forefoot pathologies.
• Identify conservative and surgical treatments for common forefoot pathology.
• Learn the stepwise surgical approach to hammertoe correction.
• Understand fixation devices used for hammertoe deformity surgical correction.

Hammertoes

• Metatarsalgia is painful metatarsals, which equates to painful forefoot.

Causes

• Biomechanics/Pathomechanics
• Injury
• Autoimmune diseases (Rheumatoid arthritis)
• Neuropathy
• Genetics (long toe)
• Footwear might cause or worsen symptoms

Symptoms

• Pain
• Corns, calluses, pressure ulcers
• Toe stiffness or contracture
• Toe Cramps

Hammertoe Types

• Hammertoe is a general term for digital deformities with specific subtypes.

Hammertoe (Specific)

• Hyperextension at the MTP joint
• Flexion at the PIP joint
• Hyperextension to the DIP joint

Mallet Toe

• Flexion at the DIP joint

Claw Toe

• Hyperextension at the MTP joint
• Flexion at the PIP joint
• Flexion at the DIP joint

Hammertoe Pathomechanics

• Dynamic adaptation is described by the three hammertoe subgroups
• This does not apply to Paralytic Contractures.
• Three Subtypes include: Flexor Stabilization, Flexor Substitution, and Extensor Substitution

Flexor Stabilization

• It's a common mechanism for digital deformities.
• Typically seen in pronated feet (pes planus or pes valgus) during late stance.
• Long flexors act as supinators of the subtalar and midfoot joints during gait.
• With excessive pronation, long flexors fire earlier and longer.
• Long flexor tendons gain a mechanical advantage, overpowering intrinsic muscles.
• It's a common cause of adductovarus deformity in digits 4 and/or 5.

Flexor Substitution

• It's the least common of the hammertoe mechanisms.
• Occurs in supinated feet during late stance as flexors try to achieve heel lift.
• A weak deep posterior group is substituted by the long flexors.
• Contributing conditions include Achilles tendon/triceps surae paresis, overlengthened Achilles tendon, calcaneal gait, and loss of heel lift.

Extensor Substitution

• Weak anterior muscle groups can result to extensor tendons substituting.
• Occurs during the swing phase; may disappear during weight-bearing stance.
• During the swing phase, EDL fires early to help the foot clear the ground.
• The EDL gains mechanical advantage over lumbricals, hyperextending MTP joints.
• Weak anterior group conditions include anterior cavus and Charcot-Marie-Tooth (CMT).

Hammertoe Conservative Treatments

• Toe exercises
• Orthotics
• Shoe gear modification
• Callous care
• Padding and Strapping

Shoe gear modification

• Extra depth
• Extra wide widths
• Easy on/off closures
• Large toe box

Hammertoe Surgical Treatment Stepwise Approach

• Skin Incision
• Extensor tenotomy
• Resection of proximal phalanx head
• Extensor hood release
• MTP joint capsulotomy - dorsal
• Flexor plate release - plantar
• Possible flexor tendon transfer
• Arthrodesis of PIP joint (resection of base of middle phalanx)
• Fixation
• Closure
• After each step, directional pressure is applied upwards across the metatarsal head as part of the "Push-up step."

Kelikian Push-Up Test

• Done during steps 3-6 of surgical treatment.
• Relocation of MTPJ is evaluated after each step.
• Steps 8-10 are done if MTPJ position is satisfactory

Stepwise approach principles

• Variation in the literature regarding exact number of steps, however basic principles are consistent:
• Skin
• Extensor tendon
• Bone resection – head of proximal phalanx
• Hood
• Dorsal capsule
• Plantar plate
• As necessary transfer or Arthrodesis
• Fixation
• Close

Mallet Toe Repair

• Flexor Digitorum Longus (FDL) is released at the DIP joint
• Correct flexible Mallet toe for useful pressure release
• Blade (#15 or #11) is used over 18g needle

Hammertoe Repair

• Flexor Digitorum brevis (FDB) and Flexor Digitorum Longus (FDL) are released at the PIP joint
• Appropriate for correcting flexible hammertoe.
• Can be from approached lateral (FDB) or plantar (FDB and FDL)

Hammertoe repair with tendon transfer

• Flexor Digitorum Longus tendon transfer is from plantar to dorsal
• Accessed through the dorsal incision after proximal phalanx head is removed
• The FDL is identified, split, divided halves brought dorsal –one medial, one lateral, over the shaft of the proximal phalanx, and sutured under the proper tension.

Hammertoe Repair With PIP Joint

• Arthrodesis involves joint fusion where the Proximal phalanx is fused to middle phalanx
• Arthroplasty involves reconstruction or replacement of joint where scar tissue is formed at the remodeled joint

Joint Preparation

• Straight cut with power saw or with bone cutter is easy to control amount of bone removed; cutter can cruise bone and cuts may be angled
• Cup and cone reamers creates more bone-to-bone contact that allows multi direction correction; this can take too much bone

Hammertoe Repair PIP Joint Fixation Types

• Kirschner wire (K-wire): one or multiple, Stainless steel, Titanium, Nitinol, absorbable
• Screws: headed, headless, cross only PIP joint or both PIP and DIP joints
• Compression staples
• PIP joint intramedullary implants: one component, two component, and made from metal, PEEK, or OSSIOfiber

K-wire Fixation

• Single K-wire: common, no compression, ability to rotate in frontal plane, extends out tip of the toe, ability to cross MTP joint
• Double K-wire: resists rotation in frontal plane, no compression, technically challenging
• K-wire through cannulated implant

K-wire retrograde correction

• Create pilot hole in proximal phalanx
• Drive wire from base of middle phalanx out end of the toe
• Wire driver is moved from proximal end of wire to distal end of wire
• Once aligned, retrograde wire back into proximal phalanx
• Bend, clip as necessary and cap wire

K-wire function

• Extend from tip of toe
• Removed in office
• Can break before (or during!) removal
• Threaded wire must be rotated out (not pulled)

Plantar Plate Injury/Pre-dislocation Syndrome

• Pathology of the second MTPJ can include pre-dislocation syndrome, capsulitis, Freiberg's, or synovitis.
• Clinical examination cannot be overstated many of these conditions present with similar findings.
• Plain film radiographs and MRI, coupled with physical findings, may be the best for examinations for diagnosis.
• Addressing lesser MTPJ pathology includes tendon transfers, osteotomies, soft tissue balancing, as well as arthrodesis.
• Plantar plate repair is rarely done as an isolated procedure, as each foot presents a variety of symptoms and findings.
• Primary plantar plate repair has proven to be a safe and effective surgical option in one of the more difficult conditions.
• Patient education is critical, it may be necessary to that complete resolution may be unreasonable in severe cases.
• Regardless of diagnosis, off-loading and stabilization are first-line treatments along with physical therapy.
• The addition of oral/intra-articular anti-inflammatory modalities and shoe modification as well. When conservative care has failed there are many surgical procedures to consider which when performed appropriately may be effective.

"Pre" Plantar Plate Dislocation Stages

• Stage 1: mild edema of lesser MTP joint, plantar and dorsal; plantar distal pain; digit alignment may appear unchanged
• Stage 2: moderate edema; noticeable digit deviation; loss of weight bearing
• Stage 3: No longer "Pre", moderate edema, greater deviation

Diagnostic techniques

• Clinical picture
• Digital Lachman's test
• Ultrasound
• Arthrogram
• MRI with or without contrast
• Common clinical findings are disuse, age, and previous injections.
• Digital Lachman’s: A vertical stress test where the proximal phalanx at the MTP joint is assessed for dorsal translation. Don’t confuse dorsal translocation from dorsiflexion.
• Bouche paper pull out test is a weight bearing examination used to test plantar flexion strength at the lesser MTP joints

Bone Scan

• Not specific, but helpful to distinguish stress fractures.

Pre-dislocation Syndrome of Lesser MTP Joints

• Early stages involve inflammation of the plantar structures of the MTP joint, with potential plantar plate and capsule attenuation.
• Conservative treatment includes taping, metatarsal pads, Budin splints, NSAIDs, RICE, shoe or boot immobilization.

Dislocated Repair

• When joints are surgically dislocated, a repair is needed to realign.
• A Weil osteotomy is a surgical realignment of the metatarsal.

Weil Osteotomy

• Indicated to translate the capital fragment in the desired digital direction.
• When the digit deviates medially, the metatarsal is cut obliquely and shifted beneath. Capital fragment shift occurs in the transverse plane (medial to lateral).
• A black line indicates a traditional Weil dorsal cut. A red line indicated an oblique cut and shows the drill bit's direction for screw fixation.
• Also used with a wedge or water and elevate the plantar flexed metatarsal.

Repair - Dorsal/Plantar

• Procedures that surgically repairs the plantar plate.

Direct Plantar Approach Pearls

• Passing a K-wire through the joint from dorsal to plantar helps identify the plantar location.
• If end-to-end repair is not possible, a small suture anchor into the plantar proxiamla phalanx base can provide a fixed insertion for plantar plate.
• Plantar plate suture is tied last
• Plantar Plate repairs are not done in isolation

Freiberg's Disease

• Avascular necrosis (AVN) or osteochondrosis of the second metatarsal head
• Smillie's classification was based on intraoperative findings, but has since been adapted to x-ray and other advanced imaging findings
• Stages 1, 2, and 3 may be treated with conservative methods. Stage 4 & 5 require surgical intervention.

Interventions for Freiberg's include

• Debridement with subchondral drilling without osteotomy
• Debridement with osteotomy - to shorten and/or dorsiflex
• Cartiva Synthetic Cartilage, Silastic implants, Swanson silicone
• An osteochondral graft (from knee or talus).
• Autologous tendon graft (anchovy graft) is also used for interposition arthroplasty
• Metallic toe joint replacement
• Second MTP joint arthrodesis (fusion)

Metatarsal Stress Fractures

• A differential diagnosis for forefoot pain caused my overuse.
• Often correlated with increased activity.
• Classic swelling and bruising with erythema
• Pain with palpation of metatarsal and shaft
• Positive tuning fork test.
• Management includes immobilization, rest/activity modification, ice/elevation and may require serial radiographs every 2-3 weeks

Plain Film Radiographs

• Early changes are subtle
• The edges may have disruptions
• If plain film radiographs are inconclusive, order an MRI

On the MRI

• Second metatarsal will appear bright white and other matatarsals will be dark

Nonunion Fractures

• Can develop into displaced fracture

Metatarsal Fractures Treatments

• Conservative treatments are for minimally displaced fractures
• These include immobilization with a rocker shoe or boot or cast and rest and activity modification combined with ice and elevation
• Serial radiographs every 2-3 week

Surgically Indicated Fractures

• Displacement greater than 4 mm
• Angulation greater than 10 degrees
• Instability with comminution
• Instability with multiple fractures
• Multiple views to visualize displacement

Fixation

• Fixations for fractures includes and ORIF percutaneously, and plates and Screws

Fractures healed

• Can result in shortening with a large bone callous.

Assessment With Mal-alignment Symptoms

• Palpable bony hypertrophy dorsally- Palpable plantar depression
• Painful prominent third met that has Oblique osteotomy dorsal
• Distal fragment the translocated (slid) distal inferior.

Goals of Fixation

• To reestablish the metatarsal parabola, you must elongate and plantar flex that plantar flexed and elongated metatarsal.