Abstract

An endoprosthetic metatarso-phalangeal replacement joint permitting dorsi and plantar flexion with minimal medial and lateral motion and true ginglymus motion. The device includes a male joint member that is surgically implanted in the proximal phalangeal base, the male member including a metallic cylinder connected to a tissue-inert plastic intramedullary stem, the cylinder having inert material embedded therein integrally coupled to said stem forming a drum-shaped head. The embedded inert material walls at each end of the head are recessed. The female joint member includes a molded, tissue-inert plastic intramedullary stem integrally formed with a socket having a partially cylindrical wall of a predetermined arcuate length relative to the axis longitudinally of the intramedullary stems that receives the drum-shaped head of the male joint member. The socket side walls include axially aligned conical protuberances that are received in the recessed walls of the drum-shaped head when male and female members are joined. A hemispherically shaped, elastic shield fits over the joint head and socket when engaged and is tapered so as to not become impinged when dorsi flexion within the foot is experienced. The intramedullary stems are longitudinally axially aligned with the axial rotation center of the head and socket. The device may be utilized as a replacement joint for either the hallux or the lesser metatarso-phalangeal joints.