Which statement best describes stability of the 1st MPJ?

• A. All of the above
• B. Collateral ligaments
• C. Suspensory sesamoid ligaments
• D. Plantar sesamoid ligament

Answer: (D)

Stability at the first metatarsophalangeal joint is built primarily from the plantar structures that secure the sesamoid apparatus under the metatarsal head and resist hyperextension. The plantar sesamoid ligaments lash the sesamoids to the proximal phalanx and to each other, creating a strong plantar tether that keeps the sesamoids aligned and helps convert tendon pull into stable plantar support during propulsion. This plantar connection is the chief line of resistance against dorsal drift of the proximal phalanx and loss of stability at push-off. While collateral ligaments provide some side-to-side stability and the suspensory ligaments help maintain sesamoid alignment, the plantar sesamoid ligaments most directly define the primary stabilizing mechanism of the 1st MPJ.