| Introduction |
 Most frequent monoarticular synovitis of the MTP joints- Epidemiology
- risk factors
- elongated second metatarsal relative to the first metatarsal
- hallux valgus deformity
- Pathoanatomy
- synovitis causes the capsuloligamentous apparatus of the MTP joint to become stretched
- stretching leads to instability
- instability leads to deformity
- attenuation of plantar plate
- extension of MTP joint
- sagital plane deformity
- MTP instability can lead to dorsal dislocation of MTP joint
- predisposition to hammer toe deformity
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| Anatomy |
- Cadaveric cross section of plantar plate
- MRI of plantar plate
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| Presentation |
- Symptoms
- pain
- warm joint
- fullness of joint
- Physical exam
- pain and tenderness
- may have pain in second web space
- tenderness may be worse plantarly over plantar plate or over dorsal capsule
- caused by inflammation or extrinsic pressure on interdigital nerve
- global swelling of MTP
- motion
- decreased plantar flexion
- deformity & motion
- deformity is often passively correctable in the predislocation stages
- instability, if present, can be demonstrated with the dorsal drawer test
- if able to dorsally sublux then attenuation of plantar plate present
- as deformity progresses second toe may cross over adjacent toe in a varus or valgus deformity
- disruption of a collateral ligament and the plantar plate
- "cross over toe deformity"
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| Imaging |
- Radiographs
- recommended views
- weight-bearing AP and lateral views of foot
- findings
- widening or medial-lateral joint space imbalance of second MTP joint
- dorsal subluxation of MTP joint
- may appear like joint space narrowing or overlapping of the proximal phalanx on distal metatarsal head
- varus or valgus deformity of toe
- MRI
- indications
- if diagnosis unclear
- quantify the extent of plantar plate or ligamentous disruption
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| Differential |
- Morton's neuroma
- may mimic Mortons neuroma
- important to differentiate MTP synovitis from interdigital neuroma because a steroid injection into the interdigital space may weaken the capsuloligamentous structures at MTP joint leading to progressive deformity
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| Treatment |
- Nonoperative
- activity/shoe wear modifications, NSAIDs, external support of MTP joint
- indications
- technique
- external support with crossover taping or Budin-type toe splint
- nonoperative treatment should last 10 to 12 weeks
- subsequently avoid shoes that aggravate symptoms
- Operative
- synovectomy
- indications
- no deformity
- failure of nonoperative treatment
- distal oblique shortening MT osteotomy (Weil procedure)
- indications
- fixed deformity with long second metatarsal
- technique
- preserves joint
- rebalances metatarsal cascade
- relaxes plantar plate and rebalances alignment
- FDL-to-EDL tendon transfer (Girdlestone-Taylor) or MTP capsular release with extensor tendon lengthening
- indications
- fixed deformity and NO long second metatarsal
- sagittal deformity
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| Complications |
- Vascular compromise
- if correcting a chronic dislocation the soft tissue, including vasculature, can contract
- stretching of the vasculature can compromise flow
- procedure may need to be reversed to save digit
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