Feasibility of First Metatarsophalangeal Joint Injections for Sesamoid Disorders: A Cadaveric Investigation

Objective: To determine whether accurately placed first metatarsophalangeal joint (MTPJ) injections consistently deliver injectate to the metatarsosesamoid articulations. Design: Prospective anatomic cadaver study. Setting: Procedural skills laboratory at a tertiary care academic institution. Participants: Five unembalmed cadaveric lower limb specimens, free from trauma, surgery, or major deformity of the medial forefoot. Methods: Ultrasound guidance was used to accurately inject the first MTPJs of each cadaveric specimen with diluted, blue-colored latex. At a minimum of 24 hours after injection, each specimen was dissected to determine whether the latex was present between the metatarsal head and sesamoid bones (metatarsosesamoid articulations). Main Outcome Measures: The presence or absence of latex within the first MTPJ and both the tibial and fibular metatarsosesamoid articulations. Results: In all 5 cadaveric specimens, ultrasound-guided first MTPJ injection accurately delivered latex into the first MTPJ. In addition, in each specimen, latex was seen between the metatarsal head and both the fibular and tibial sesamoid bones. Conclusions: Accurate first MTPJ injections reliably deliver latex to the articular surfaces of the metatarsosesamoid articulations. Clinicians administering diagnostic or therapeutic injections for patients with sesamoid disorders should consider injecting the first MTPJ as an alternative to direct metatarsosesamoid articulation injections.