SESAMOID DISORDERS
Hallucal Sesamoid Pathology | Tibial and Fibular Sesamoids | Sesamoidectomy Complications
Spectrum of Sesamoid Pathology
Critical Must-Knows
- Tibial (medial) sesamoid bears more weight and is most commonly affected (25:1 ratio)
- Bipartite sesamoid has smooth corticated margins, bilateral in 85%, larger total volume
- MRI is gold standard for differentiating sesamoiditis, fracture, and AVN
- Conservative management successful in over 90% of cases - trial 3-6 months minimum
- Sesamoidectomy risks: hallux valgus (tibial excision), hallux varus (fibular excision), cock-up toe
Examiner's Pearls
- "Passive dorsiflexion test (Windlass mechanism) reproduces pain by loading sesamoid complex
- "Axial (skyline) radiograph view is critical for visualizing sesamoid-metatarsal articulation
- "FHB tendon repair during sesamoidectomy is mandatory to prevent cock-up deformity
- "Blood supply enters proximal pole - distal fractures have high AVN and nonunion risk
Clinical Imaging
Imaging Gallery
Critical Sesamoid Disorder Exam Points
Anatomical Foundation
Two sesamoid bones embedded in FHB tendons. Tibial (medial) and fibular (lateral) sesamoids articulate with plantar metatarsal head crista. They increase FHB mechanical advantage and absorb up to 300% body weight during gait.
Diagnostic Differentiation
Bipartite vs Fracture is critical. Bipartite: smooth margins, bilateral 85%, normal MRI signal. Fracture: sharp irregular line, unilateral, bone marrow edema on MRI. Always X-ray both feet for comparison.
Treatment Hierarchy
Conservative first for at least 6 months. Offloading orthotics (dancer's pad), stiff-soled shoes, activity modification. Surgery only for failed conservative management or displaced acute fractures requiring ORIF.
Surgical Complications
Sesamoidectomy alters biomechanics. Tibial excision leads to hallux valgus (loss of medial buttress). Fibular excision leads to hallux varus (loss of lateral pull). Inadequate FHB repair causes cock-up toe deformity.
Quick Decision Guide
| Clinical Scenario | Imaging Findings | First-Line Treatment | Key Pearl |
|---|---|---|---|
| Insidious onset plantar pain, dancer/runner | Normal radiographs, MRI shows bone marrow edema | Conservative: offloading, NSAIDs, activity modification | Typical sesamoiditis - 90% resolve non-operatively |
| Acute traumatic event, immediate pain | Sharp irregular fracture line, unilateral | NWB cast/boot 6 weeks, consider ORIF if displaced | Differentiate from bipartite - check contralateral foot |
| Chronic pain despite 6 months conservative | Sclerosis, fragmentation, joint space narrowing | Sesamoidectomy consideration | AVN or sesamoid arthritis - surgical candidate |
| Bilateral smooth-margined two-part sesamoid | Rounded corticated margins, symmetric bilaterally | Asymptomatic - no treatment needed | Normal variant in 10-30% population - not a fracture |
CHOVSesamoidectomy Complications
Memory Hook:CHOV (Shove) away these complications with meticulous surgical technique and FHB repair!
TIBIADifferential Diagnosis of Sesamoid Pain
Memory Hook:The TIBIA bears weight - remember all causes of sesamoid pain under the first ray!
SMOOTHFeatures Distinguishing Bipartite from Fracture
Memory Hook:A SMOOTH diagnosis on imaging prevents unnecessary treatment of a normal variant!
Overview and Epidemiology
Clinical Importance of Sesamoid Disorders
Hallucal sesamoid pathology represents a spectrum from benign anatomical variants (bipartite sesamoid) to debilitating conditions requiring surgery (AVN, nonunion). The tibial sesamoid is the most commonly affected due to increased weight-bearing forces and more variable vascular supply. Understanding the differential diagnosis and appropriate imaging is critical for exam scenarios.
Demographics
- Population: Athletes, dancers, runners most affected
- Age: Typically 20-40 years for acute injuries
- Gender: Male and female equally affected
- Activity: Ballet (relevé position), running (push-off phase), basketball (jumping)
- Footwear: High heels increase forefoot loading
Risk Factors
- Foot morphology: Cavus foot (rigid, peaked MTPJ angle)
- Plantarflexed first ray: Drives sesamoid into ground
- Gastrocnemius tightness: Equinus deformity prolongs forefoot loading
- Training errors: Sudden volume increase, hard surfaces
- Previous injury: Prior sesamoid pathology increases reinjury risk
Anatomy and Biomechanics
Vascular Anatomy Critical for Fracture Management
The sesamoids receive their blood supply predominantly from vessels entering the proximal pole via branches of the medial plantar artery and plantar arch. This makes distal pole fractures particularly prone to avascular necrosis and nonunion due to disruption of the main vascular pedicle.
Sesamoid Complex Anatomy
The hallucal sesamoids are two small ovoid bones embedded within the tendons of flexor hallucis brevis (FHB), located plantar to the first metatarsal head.
Bony Anatomy:
- Tibial Sesamoid (Medial): Typically more elongated, bears greater weight
- Fibular Sesamoid (Lateral): More rounded, bears less load
- Articular Surface: Dorsal surface articulates with plantar metatarsal head crista
- Non-articular Surface: Plantar surface gives attachment to plantar plate and FHB
Soft Tissue Relationships:
| Structure | Relationship to Sesamoids | Clinical Significance |
|---|---|---|
| Flexor Hallucis Brevis (FHB) | Medial head encases tibial sesamoid; lateral head encases fibular | Main stabilizer - repair mandatory during sesamoidectomy |
| Intersesamoid Ligament | Strong fibrous band connecting the two sesamoids | Prevents separation; rupture occurs in severe turf toe |
| Flexor Hallucis Longus (FHL) | Passes in groove between sesamoids plantarly | Protected from ground contact; can develop tendonitis |
| Abductor Hallucis | Inserts partially on tibial sesamoid medially | Tibial excision allows valgus drift from loss of medial pull |
| Adductor Hallucis | Inserts on fibular sesamoid laterally | Fibular excision causes varus from unopposed abductor |
| Plantar Plate | Thick fibrocartilaginous structure attaching to sesamoids | Turf toe involves plantar plate rupture with sesamoid retraction |
Biomechanical Function
The sesamoids serve multiple critical functions in first ray biomechanics:
- Mechanical Advantage: Increase moment arm of FHB by elevating the tendon away from joint center
- Load Absorption: Bear 2-3 times body weight during walking, up to 300% during running
- FHL Protection: Elevate metatarsal head to protect FHL tendon from compressive forces
- Weight Distribution: Distribute forces across metatarsal head during gait
Windlass Mechanism:
During toe-off, hallux dorsiflexion tightens the plantar fascia, elevating the arch and depressing the first metatarsal head. This dramatically increases force transmission through the sesamoid complex. Any pathology causing sesamoid pain disrupts this mechanism, leading to compensatory gait changes and potential transfer metatarsalgia.
Tibial Sesamoid Characteristics
- Position: Medial, more prominent plantarly
- Load: Bears approximately 60% of sesamoid complex load
- Pathology: 25 times more likely to fracture than fibular
- Excision Effect: Hallux valgus deformity risk
- Blood Supply: More variable, higher AVN risk
Fibular Sesamoid Characteristics
- Position: Lateral, less prominent
- Load: Bears approximately 40% of sesamoid complex load
- Pathology: Fractures and AVN less common
- Excision Effect: Hallux varus deformity risk
- Blood Supply: More consistent arterial supply
Pathophysiology
Mechanisms of Sesamoid Pathology
Sesamoid disorders develop through several distinct pathophysiological mechanisms. Understanding these processes is essential for appropriate diagnosis and management.
Overuse and Repetitive Microtrauma:
Sesamoiditis represents an inflammatory response to chronic repetitive loading. During the push-off phase of gait, the sesamoid complex experiences forces up to 300% of body weight. In athletes performing repetitive toe-off activities (ballet, running, jumping), cumulative microtrauma exceeds the tissue's healing capacity, resulting in:
- Bone marrow edema visible on MRI
- Periosteal inflammation
- Soft tissue swelling in FHB tendons and plantar plate
- Bursitis between sesamoid and metatarsal head
Stress Fracture Development:
When cyclical loading exceeds bone remodeling capacity, stress fractures develop through a predictable sequence:
- Stress Reaction: Increased osteoclastic activity creating microscopic trabecular damage
- Cortical Disruption: Fracture line appears as bone remodeling fails to keep pace
- Propagation: Continued loading extends the fracture through cortex
- Displacement: In severe cases, complete cortical break with fragment separation
The tibial sesamoid is 25 times more susceptible due to increased load-bearing and more variable vascular supply.
Avascular Necrosis Pathway:
AVN develops when blood supply is critically compromised, most commonly from:
- Fracture-related: Distal pole fractures disrupt the proximal vascular pedicle
- Idiopathic: Gradual vascular insufficiency from chronic repetitive trauma
- Post-surgical: Excessive soft tissue stripping during surgery
The pathological sequence follows:
- Vascular compromise leads to osteocyte death
- Bone attempts repair but fails due to persistent ischemia
- Subchondral collapse as necrotic bone cannot support loads
- Fragmentation and sclerosis as body attempts to revascularize
- Secondary degenerative changes in metatarsosesamoid joint
Acute Traumatic Fracture:
High-energy axial loading (forced dorsiflexion, direct impact) exceeds bone's ultimate tensile strength, causing immediate fracture. Sharp irregular fracture lines differentiate these from bipartite variants. Displacement depends on magnitude of force and integrity of surrounding soft tissue envelope.
Degenerative Arthritis:
Chronic overload or post-traumatic changes lead to cartilage degeneration in the metatarsosesamoid articulation. Progressive joint space narrowing, osteophyte formation, and subchondral sclerosis follow typical osteoarthritic patterns.
Why Tibial Sesamoid Most Affected
Anatomical and biomechanical factors converge:
- Bears 60% of sesamoid complex load (vs 40% fibular)
- More prominent plantar position
- Variable vascular anatomy (higher AVN risk)
- Larger size creates greater stress concentration
- First ray plantarflexion drives tibial into ground contact
Healing Challenges
Poor healing potential due to:
- Limited blood supply (single proximal arterial pedicle)
- Constant mechanical loading during ambulation
- Small bone size limits revascularization
- Embedded in tendon creates shear forces
- Poor soft tissue coverage plantarly
Classification Systems
Spectrum of Sesamoid Disorders
Sesamoid pathology exists on a continuum from normal variants to surgical conditions. Classification is descriptive based on etiology and imaging characteristics.
| Condition | Mechanism | Imaging Features | Treatment Approach |
|---|---|---|---|
| Sesamoiditis | Repetitive microtrauma, overuse inflammation | Radiographs normal; MRI shows bone marrow edema | Conservative: offloading, NSAIDs, activity modification |
| Stress Fracture | Cyclical loading exceeds bone remodeling capacity | Fine cortical break; MRI high T2 signal with surrounding edema | NWB immobilization 6-8 weeks in walking boot |
| Acute Fracture | Single high-energy traumatic event | Sharp irregular fracture line, possible displacement | Cast immobilization vs ORIF if displaced over 2mm |
| Osteonecrosis (AVN) | Vascular compromise, often post-fracture | Sclerosis, fragmentation, collapse, loss of height | Sesamoidectomy if symptomatic and failed conservative |
| Bipartite Sesamoid | Congenital variant (multipartite ossification) | Smooth corticated margins, bilateral 85%, larger volume | Usually asymptomatic; conservative if symptomatic synchondrosis |
| Sesamoid Arthritis | Degenerative changes in metatarsosesamoid articulation | Joint space narrowing, osteophytes, subchondral sclerosis | Conservative first; sesamoidectomy or shaving if severe |
Understanding this spectrum is essential for appropriate treatment selection in exam scenarios.
Clinical Assessment
History
A detailed history often reveals the underlying pathology type.
Key Questions:
- Onset: Insidious (sesamoiditis, stress fracture) vs acute (traumatic fracture, turf toe)
- Mechanism: Forced dorsiflexion (turf toe), repetitive push-off (sesamoiditis), single impact (acute fracture)
- Activity: Ballet dancers (relevé position), runners (push-off phase), basketball players (jumping)
- Pain Characteristics: Localized plantar pain worsened by toe-off phase of gait
- Footwear: High heels, cleats, or minimalist shoes increase forefoot loading
- Previous Symptoms: Prior episodes suggest chronic overload or bipartite variant
Classic Presentation by Pathology
- Sesamoiditis: 25-year-old ballet dancer, insidious onset over weeks, worsened by relevé
- Stress Fracture: 30-year-old marathon runner, progressive pain over 2-4 weeks, no specific event
- Acute Fracture: 22-year-old footballer, immediate pain after forced dorsiflexion tackle
- Bipartite: Incidental finding on radiographs for unrelated foot pain, bilateral
Physical Examination
Systematic examination localizes pathology and rules out differential diagnoses.
Examination Sequence
- Swelling: Mild plantar MTPJ edema suggests active inflammation
- Erythema: Redness may indicate gout, infection, or acute injury
- Callosities: Intractable plantar keratosis (IPK) under sesamoid indicates prominence
- Alignment: Check for cavus foot (high arch), hallux valgus, or first ray plantarflexion
- Gait: Antalgic gait with shortened stride and early heel rise to avoid push-off
- Point Tenderness: Direct pressure over specific sesamoid reproduces pain
- Dorsal vs Plantar: Ensure pain is plantar (sesamoid) not dorsal (arthritis, gout)
- Joint Line: Palpate MTPJ for synovitis or effusion
- FHL Excursion: Pain with FHL gliding suggests tendonitis
- Neurovascular: Check sensation (medial plantar nerve) and pulses
- Passive Dorsiflexion Test: Extend hallux while palpating sesamoid - reproduces pain by loading complex
- Resisted Flexion: Active flexion against resistance tests FHB/FHL integrity
- Push-off Test: Single leg heel raise - inability indicates significant pain
- Grind Test: Compression plus rotation reproduces arthritic pain
- Vertical Lachman: Dorsal translation indicates plantar plate injury (turf toe)
This completes the clinical examination sequence.
Red Flags Requiring Urgent Workup
- Erythema + Fever + Systemic Symptoms: Septic arthritis or osteomyelitis
- Gout Crystals: Aspirate and send for crystal analysis if suspicious
- Neurovascular Compromise: Rare but check pulses and sensation
- Unable to Weight Bear: Suggests displaced fracture or complete plantar plate rupture
Investigations
Imaging Protocol
A systematic approach to imaging ensures accurate diagnosis and appropriate treatment selection.
Stepwise Imaging Strategy
Essential Views:
- AP Foot: Assess sesamoid alignment, fracture diastasis, bipartite margins
- Lateral Foot: Check for sesamoid height, proximal migration (turf toe)
- Axial (Skyline) Sesamoid View: Critical for visualizing sesamoid-metatarsal articulation
What to Look For:
- Bipartite Features: Smooth rounded margins, bilateral symmetric appearance
- Fracture Features: Sharp irregular fracture line, unilateral
- AVN Features: Sclerosis, fragmentation, collapse, loss of height
- Arthritis: Joint space narrowing, osteophytes, subchondral cysts
Critical: Always obtain bilateral comparison radiographs to assess for bipartite variant symmetry.
Radiographic assessment is the foundation of sesamoid disorder diagnosis.
Gold Standard for Sesamoid Pathology
MRI provides definitive diagnosis when radiographs are normal or equivocal.
Sequences and Findings:
- T1-weighted: Low signal indicates edema, AVN, or chronic changes
- T2/STIR: High signal confirms acute bone marrow edema
- Proton Density: Evaluates cartilage integrity and plantar plate
Diagnostic Patterns:
- Sesamoiditis: Bone marrow edema, intact cortex, normal FHB and plantar plate
- Stress Fracture: Linear T2 hyperintensity, surrounding edema, cortical disruption
- AVN: Low T1/T2 signal (sclerosis), fragmentation, subchondral collapse
- Bipartite Symptomatic: Edema at synchondrosis junction; asymptomatic shows normal signal
- Turf Toe: Plantar plate rupture, capsular tear, joint effusion, sesamoid retraction
MRI is the definitive test for difficult diagnostic scenarios.
- CT Scan: Best for assessing fracture healing (union vs nonunion), bony architecture, and surgical planning
- Bone Scan: High sensitivity for stress reactions and sesamoiditis but low specificity
- Use Case: CT for nonunion evaluation; bone scan if MRI contraindicated
Advanced imaging complements the diagnostic workup.
Bipartite Sesamoid Diagnostic Criteria
Five Features Confirming Bipartite Variant (Not Fracture):
- Smooth Corticated Margins: Rounded edges vs sharp jagged fracture line
- Bilateral Symmetry: Present in both feet (85% of cases) - always check
- Larger Total Volume: Sum of fragments exceeds normal single sesamoid size
- Unequal Fragment Sizes: Typically one large and one small piece
- Normal MRI Signal: No bone marrow edema unless symptomatic synchondrosis injury
If unsure, MRI is definitive - fractures show surrounding edema, bipartite does not (unless symptomatic).
Management Algorithm
Non-Operative Treatment - First-Line for All Sesamoid Disorders
Over 90% of sesamoid disorders resolve with conservative management. A minimum 3-6 month trial is mandatory before surgical consideration.
Stepwise Conservative Protocol
Activity Modification:
- Complete cessation of aggravating activity (running, dancing, jumping)
- Transition to non-impact exercise (swimming, cycling)
Immobilization:
- Stiff-soled shoe or rocker-bottom shoe to limit MTPJ extension
- Short leg walking boot (CAM boot) for acute fractures or severe pain
- Non-weight-bearing for 2 weeks if acute fracture, then heel weight-bearing
Orthotic Offloading:
- Dancer's Pad: Felt pad with U-shaped cutout to float the painful sesamoid
- Sesamoid Relief Orthotic: Depression under sesamoid with metatarsal bar proximal
- Full-length Custom Orthotic: With first ray extension and arch support
Pharmacological:
- NSAIDs: Ibuprofen 400mg TDS or naproxen 500mg BD for 2-4 weeks
- Ice: 15-20 minutes TDS to reduce inflammation
Initial phase focuses on pain control and offloading.
Physical Therapy:
- Intrinsic Strengthening: Towel curls, marble pickups
- Gastrocnemius Stretching: Address equinus contracture
- Arch Strengthening: Short foot exercises
- FHL/FHB Strengthening: Resistance band exercises
Injections (Selective Use):
- Corticosteroid Injection: Diagnostic and therapeutic for sesamoiditis
- Technique: Fluoroscopic or ultrasound-guided to ensure accurate placement
- Limit: Maximum 1-2 injections (risk of fat pad atrophy and tendon weakening)
- Contraindication: Infection, acute fracture
Adjuncts:
- Bone Stimulator: For stress fractures or delayed healing
- Contrast Baths: Vascular flushing
- Iontophoresis: Dexamethasone penetration
Rehabilitation phase builds strength and addresses biomechanical factors.
Gradual Progression:
- Week 1-2: Walking tolerance without pain
- Week 3-4: Brisk walking and light jogging
- Week 5-8: Running progression (50%, 75%, 100% intensity)
- Week 9-12: Sport-specific drills and return to full activity
Permanent Modifications:
- Continue orthotic use indefinitely for impact activities
- Address biomechanical factors (cavus foot correction, equinus treatment)
- Footwear selection (avoid minimalist shoes, high heels)
Return to activity requires patience and gradual progression.
Conservative management is successful in the vast majority of cases when compliance is good and offloading is adequate.
Surgical Technique
Total Sesamoidectomy - Medial (Tibial) Approach
Technique for excision of the tibial (medial) sesamoid - the most commonly affected.
Preoperative Planning
- Confirm diagnosis: MRI showing AVN, nonunion, or arthritis
- Trial conservative: Minimum 6 months documented
- Counsel risks: Hallux valgus (10-15%), cock-up toe (5-10%), transfer metatarsalgia
- Imaging review: Assess remaining sesamoid health (avoid double sesamoidectomy)
Patient Positioning and Setup
- Position: Supine with sandbag under ipsilateral hip (prevents external rotation)
- Tourniquet: Thigh tourniquet preferred; ankle tourniquet acceptable
- Anesthesia: General or popliteal regional block (block provides excellent postop pain control)
- Fluoroscopy: Mini C-arm available to confirm complete excision
Operative Steps
Medial Approach (Preferred):
- Longitudinal incision 3-4cm centered over medial aspect of MTPJ
- Avoid direct plantar incision (painful weight-bearing scar)
- Identify and protect dorsomedial cutaneous nerve (retract dorsally)
- Deepen to joint capsule in line with skin incision
Plantar Approach (Alternative):
- Curvilinear incision plantar to sesamoid (between weight-bearing areas)
- Higher risk to medial plantar nerve branches
- Direct visualization but potential painful scar
- Reserved for plantar pathology requiring direct access
Approach selection depends on pathology location and surgeon preference.
- Longitudinal capsulotomy along sesamoid axis
- Identify sesamoid within FHB tendon substance
- Divide metatarsosesamoid ligament (suspensory ligament)
- Inspect metatarsal head articular surface for arthritis
- Assess plantar plate integrity
Adequate exposure is essential for safe sesamoid removal.
"Shelling Out" Technique:
This is the most critical step to preserve FHB function.
- Use Beaver blade (#64 or #67) or small #15 scalpel
- Carefully dissect sesamoid from surrounding FHB tendon fibers
- Preserve as much tendon as possible - do not excise tendon with bone
- Remove all bony fragments (check with fluoroscopy)
- Inspect FHL tendon deep to sesamoid for pathology
Key Point: The sesamoid is embedded in the tendon, not attached to it. Careful dissection preserves the flexor mechanism integrity.
Meticulous technique prevents complications.
Repair of Flexor Apparatus:
- Close the longitudinal defect in FHB tendon with #1 Vicryl or PDS suture
- Use figure-of-8 or horizontal mattress technique
- Restore tension to prevent cock-up deformity
- Ensure hallux can plantarflex actively before closure
Soft Tissue Balancing:
- Tibial Sesamoidectomy: Consider abductor hallucis release if pre-existing valgus
- Fibular Sesamoidectomy: Consider adductor hallucis release to prevent varus
- Test alignment - hallux should sit in neutral without drift
Tendon repair is the most important step preventing complications.
- Capsule closed with 2-0 Vicryl (restore static stability)
- Subcutaneous layer with 3-0 Monocryl
- Skin with 3-0 or 4-0 nylon or Monocryl subcuticular
- Sterile dressing and post-op shoe or walking boot
Meticulous closure completes the procedure.
Critical Technical Point
Failure to repair the FHB tendon defect is the single most common cause of cock-up toe deformity post-sesamoidectomy. The intrinsic flexor power is lost, allowing unopposed extensor pull causing MTP hyperextension and IP flexion (claw toe). Always test active plantarflexion before closure.
Complications
Sesamoidectomy Complications - Mechanism, Prevention, Management
| Complication | Mechanism | Prevention Strategy | Management |
|---|---|---|---|
| Hallux Valgus Drift | Tibial sesamoidectomy removes medial buttress; unopposed lateral pull from adductor | Meticulous FHB repair; consider abductor release if pre-existing valgus | Early: orthotic and taping; Late: distal metatarsal osteotomy or MTP fusion |
| Hallux Varus Deformity | Fibular sesamoidectomy removes lateral stabilizer; unopposed medial pull | FHB repair; consider adductor release at time of excision | EHL split transfer (reverse Jones) or MTP fusion if rigid |
| Cock-up Toe (MTP Hyperextension) | Loss of FHB flexor function from inadequate tendon repair | Robust tendon repair with #1 Vicryl; test active plantarflexion before closure | Girdlestone-Taylor FDL transfer or MTP fusion |
| Transfer Metatarsalgia | Loss of first ray weight-bearing; overload of lesser metatarsals | Custom orthotic with met pad; avoid excessive first ray elevation | Metatarsal osteotomies (Weil) to equalize metatarsal parabola |
| Neuroma Formation | Injury to medial plantar nerve or dorsomedial cutaneous nerve | Careful dissection; early identification and retraction of nerves | Nerve excision proximal to weight-bearing area; bury in muscle |
| Persistent Pain | Incomplete excision of fragments; arthritis in remaining sesamoid | Fluoroscopy to confirm complete removal; assess other sesamoid preop | Revision excision or contralateral sesamoidectomy (if necessary) |
| Stiffness (Loss of ROM) | Capsular fibrosis, prolonged immobilization | Early ROM exercises (2 weeks postop); aggressive PT | Manipulation under anesthesia; capsular release if severe |
Complication Rates
Published literature reports:
- Overall satisfaction: 85-95% at 2-year follow-up
- Hallux valgus/varus: 5-15% (reduced with modern repair techniques)
- Cock-up toe: 5-10% (preventable with FHB repair)
- Transfer metatarsalgia: 10-20% (managed with orthotics)
- Neuroma: 5% (nerve protection critical)
The key to minimizing complications is meticulous surgical technique with emphasis on FHB tendon preservation and repair.
Postoperative Care and Rehabilitation
Rehabilitation Protocol After Sesamoidectomy
Immobilization:
- Post-op stiff-soled shoe or short leg walking boot
- Weight-bearing: Heel weight-bearing only (avoid push-off)
- Strict elevation to prevent hemarthrosis and swelling
Wound Care:
- Keep clean and dry
- Suture or staple removal at 14 days
- Monitor for signs of infection
Immediate postoperative care focuses on wound healing.
Range of Motion:
- Start passive and active MTPJ ROM exercises at 2 weeks
- FHL excursion exercises (toe curls, towel grabs)
- Avoid aggressive dorsiflexion (protect repair)
Weight-Bearing Progression:
- Transition from heel weight-bearing to full forefoot loading
- Progressive weight-bearing in stiff-soled shoe
- Wean from boot by week 4-6 based on pain
Scar Management:
- Scar massage and desensitization (especially plantar incisions)
- Silicone sheeting to minimize hypertrophic scarring
Early mobilization prevents stiffness.
Physical Therapy:
- Intrinsic foot strengthening (short foot exercises)
- Gastrocnemius/soleus stretching
- Proprioception training (single leg balance)
- Progressive resistance exercises
Footwear:
- Transition to supportive athletic shoe
- Custom orthotic with sesamoid cutout or dancer's pad
- Rocker-bottom sole to reduce MTPJ extension forces
Strengthening phase prepares for return to activity.
Activity Progression:
- Month 3: Walking unlimited, stationary cycling, swimming
- Month 4: Light jogging, elliptical trainer
- Month 5: Running progression (50%, 75%, 100% intensity)
- Month 6: Sport-specific drills, return to full activity
Monitoring:
- Watch for hallux drift (valgus/varus) - early taping can correct
- Monitor for transfer metatarsalgia - adjust orthotics
- Assess for loss of push-off power - strengthen FHL/FHB
Permanent Modifications:
- Continue orthotic use indefinitely for impact sports
- Avoid minimalist footwear or high heels
- Maintain gastrocnemius flexibility
Return to sport requires gradual progression and monitoring.
Bone Grafting Protocol (Stricter)
For bone grafting procedures, rehabilitation is more conservative:
- NWB strict for 8 weeks in short leg cast
- Radiographs at 6 and 12 weeks to confirm union
- Transition to weight-bearing boot weeks 8-12
- Full weight-bearing by 12 weeks if healed
- Return to sport 6-9 months (slower than sesamoidectomy)
Evidence Base
Sesamoidectomy Return to Sport Meta-Analysis
- Systematic review of 196 feet (14 studies) undergoing sesamoidectomy
- Return to sport rate: 92.5% at mean 4.8 months
- Complication rate: 15.5% (neuralgia, infection, transfer metatarsalgia)
- Hallux deformities rare with modern repair techniques (less than 10%)
- Concluded sesamoidectomy is safe and effective for athletes failing conservative
Bone Grafting for Sesamoid Nonunion
- 9 elite athletes with tibial sesamoid nonunion treated with bone grafting and screw fixation
- 100% union rate at mean 14 weeks
- All patients returned to full sports activity without loss of push-off power
- No cases of AVN or hardware complications
- Mean time to return to sport: 6 months
Conservative Management Efficacy
- Retrospective review of 43 patients with sesamoid pain
- 88% resolved with non-operative treatment (offloading orthotics, activity modification, NSAIDs)
- Mean time to resolution: 5.2 months
- Factors predicting failure: AVN on MRI, inflammatory arthropathy, cavus foot
- Emphasizes need for prolonged conservative trial (minimum 6 months)
MRI Diagnostic Accuracy for Sesamoid Pathology
- MRI 96% sensitive for diagnosing sesamoid disorders
- Key differentiator: bipartite sesamoid shows normal marrow signal on T1/T2
- Symptomatic bipartite demonstrates edema at synchondrosis junction
- AVN shows low T1/T2 signal (sclerosis) with fragmentation
- Stress fractures show linear T2 hyperintensity with surrounding edema
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: The Dancer with Plantar Foot Pain
"A 22-year-old professional ballet dancer presents with 4 months of progressive pain under the great toe. Worse in relevé position. No specific trauma. Exam shows point tenderness over the medial plantar MTPJ and pain with passive dorsiflexion. Weight-bearing radiographs show a two-part medial sesamoid with smooth margins."
Scenario 2: The Non-Healing Fracture in an Athlete
"A 28-year-old professional footballer sustained a tibial sesamoid fracture 6 months ago. He was treated in a boot NWB for 8 weeks then progressive weight-bearing. He remains symptomatic with pain on push-off. CT scan shows a persistent 2mm fracture gap with sclerotic margins suggesting nonunion. MRI shows no AVN. He is desperate to return to professional sport."
Scenario 3: Post-Sesamoidectomy Hallux Valgus Deformity
"A 35-year-old patient returns 18 months after tibial sesamoidectomy for chronic sesamoiditis. She complains that her big toe is drifting outward. On examination, there is 25 degrees of hallux valgus with a positive drawer test (MTP joint instability). Radiographs confirm progressive valgus deformity compared to immediate postoperative films."
MCQ Practice Points
Most Common Sesamoid Affected
Q: Which sesamoid is most commonly affected by fracture and AVN?
A: Tibial (medial) sesamoid - 25:1 ratio compared to fibular sesamoid. This is due to increased weight-bearing forces (tibial bears 60% of load), more prominent plantar position, and more variable vascular supply with higher AVN risk.
Bipartite Sesamoid Prevalence
Q: What percentage of the population has bipartite sesamoids?
A: 10-30% of the population has bipartite sesamoids, and they are bilateral in 85% of cases. The tibial sesamoid is 10 times more likely to be bipartite than the fibular sesamoid. This is why bilateral comparison radiographs are mandatory when evaluating suspected sesamoid fractures.
Blood Supply and AVN Risk
Q: Why are distal pole sesamoid fractures at higher risk for AVN?
A: The blood supply enters the sesamoid via the proximal pole (branches of medial plantar artery and plantar arch). Fractures through the distal pole disrupt this vascular pedicle, creating a distal fragment with compromised blood supply that is prone to avascular necrosis and nonunion.
Hallux Valgus After Sesamoidectomy
Q: Which sesamoid excision leads to hallux valgus deformity?
A: Tibial (medial) sesamoidectomy leads to hallux valgus. The tibial sesamoid and medial FHB act as a medial stabilizer. Excision removes this buttress, allowing unopposed lateral pull from the adductor hallucis, causing valgus drift. Prevention: meticulous FHB repair and consider prophylactic abductor hallucis release.
Conservative Success Rate
Q: What percentage of sesamoid disorders resolve with conservative management?
A: Over 90% of sesamoid disorders resolve with adequate conservative management (offloading orthotics, activity modification, NSAIDs, stiff-soled shoes). A minimum 3-6 month trial is mandatory before considering surgical intervention. Cohen et al. (2009) reported 88% resolution with conservative treatment alone.
Australian Context
Pharmaceutical Benefits Scheme (PBS)
- NSAIDs: Subsidized for sesamoiditis management (naproxen, ibuprofen)
- Corticosteroid injections: Not PBS-listed but widely available
- Bone stimulators: Not PBS-subsidized (patient out-of-pocket cost significant)
Access to Imaging
- MRI foot: Readily available through specialist referral under Medicare
- CT scan: Covered for assessment of nonunion or surgical planning
- Bone scan: Less commonly used but available if MRI contraindicated
Medicolegal Considerations
Informed consent for sesamoidectomy must include:
- Risk of hallux valgus or varus deformity (10-15% risk)
- Cock-up toe deformity from loss of FHB function (5-10%)
- Transfer metatarsalgia to lesser toes (10-20%)
- Neuroma formation (medial plantar or dorsomedial cutaneous nerve, 5%)
- Loss of push-off power particularly relevant for elite athletes
- Potential need for revision surgery if complications develop
Documentation should include:
- Detailed conservative management trial (minimum 3-6 months)
- MRI confirmation of pathology (AVN, nonunion, or severe arthritis)
- Discussion of sesamoid preservation alternatives (bone grafting) for athletes
- Sport-specific counseling (e.g., ballet dancers may lose career)
Australian Injury Patterns
Sesamoid injuries in Australia commonly occur in:
- AFL (Australian Rules Football): Forefoot loading during kicking
- Rugby League/Union: Push-off forces during sprinting
- Cricket: Fast bowlers (repetitive forefoot impact)
- Track and field: Sprinters and long-distance runners
Public hospital waiting times for elective sesamoidectomy: typically 6-12 months, favoring private sector treatment for athletes requiring expedited return to sport.
SESAMOID DISORDERS
High-Yield Exam Summary
Key Anatomy
- •Two sesamoids: Tibial (medial) and Fibular (lateral)
- •Embedded in FHB tendons, articulate with MT head crista
- •Blood supply: Proximal pole entry (medial plantar artery)
- •FHL tendon runs in groove between sesamoids
- •Tibial bears 60% load, Fibular 40%
Pathology Spectrum
- •Sesamoiditis: Inflammation/overuse, normal X-ray, MRI edema
- •Stress Fracture: Cortical break, MRI linear T2 high signal
- •Acute Fracture: Sharp irregular line, unilateral
- •AVN: Sclerosis, fragmentation, low T1/T2 signal
- •Bipartite: Smooth margins, bilateral 85%, normal MRI
Bipartite vs Fracture (SMOOTH)
- •Smooth corticated margins vs sharp jagged fracture line
- •Bilateral 85% - always X-ray BOTH feet
- •Larger total volume (sum of parts exceeds normal)
- •MRI normal signal (bipartite) vs edema (fracture)
Conservative Management (90% success)
- •Dancer's pad with U-shaped cutout to offload sesamoid
- •Stiff-soled shoe or CAM boot (NWB 6 weeks for fractures)
- •Activity modification: stop aggravating activity
- •NSAIDs, ice, physiotherapy
- •Minimum 3-6 month trial before surgery
Surgical Indications
- •Failed conservative minimum 6 months
- •AVN with fragmentation/collapse
- •Symptomatic nonunion
- •Displaced acute fracture over 2mm (ORIF consideration)
Sesamoidectomy Technique (Critical)
- •Medial approach (protect dorsomedial cutaneous nerve)
- •Shell out sesamoid preserving FHB tendon
- •Repair FHB with #1 Vicryl (MANDATORY)
- •Soft tissue balancing (abductor release if valgus risk)
- •Test active plantarflexion before closure
Sesamoidectomy Complications (CHOV)
- •Cock-up toe: Loss of FHB function (prevent with repair)
- •Hallux Valgus: After tibial excision (loss medial buttress)
- •Offloading loss: Transfer metatarsalgia (10-20%)
- •Varus deformity: After fibular excision (unopposed abductor)
Exam Pearls
- •Tibial:Fibular fracture ratio is 25:1
- •Bipartite bilateral in 85% - check other foot
- •Distal pole fractures high AVN risk (blood enters proximal)
- •FHB repair is critical step preventing cock-up toe
- •Sesamoidectomy 85-95% satisfaction but alters biomechanics