summary Synovitis of 2nd MTP is the most frequent monoarticular synovitis of the MTP joint frequently associated with elongated 2nd metatarsal or a hallux valgus deformity. Diagnosis is made clinically with tenderness plantarly over 2nd MTP plantar plate or over dorsal capsule. MRI can be helpful in cases of unclear diagnosis. Treatment is a trial of conservative management with shoe modifications and NSAIDs. Surgical management is indicated for patients with progressive symptoms who fail nonoperative management. Epidemiology Risk factors elongated second metatarsal relative to the first metatarsal Morton Foot hallux valgus deformity Etiology 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 sagittal plane deformity associated with cross-over toe deformity MTP instability can lead to dorsal dislocation of MTP joint predisposition to hammer toe deformity Anatomy Cadaveric cross section of plantar plate MRI of plantar plate 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 pain with range of motion decreased with traction 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" 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 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 Treatment Nonoperative activity/shoe wear modifications, NSAIDs, external support of MTP joint indications first line treatment 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 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