First Metatarsophalangeal Implants

Surgical correction of hallux limitus or degenerative articular disease of the first metatarsophalangeal joint (MPJ), whether as singular conditions or in the face of concomitant hallux abducto valgus, is a dilemma with which foot surgeons have struggled with for almost a century. The ideal procedure would provide adequate pain-free motion of the first MPJ without shortening the hallux or unweighting the first metatarsal in gait, and would withstand the rigors of weight, activity, and time. The advent of the implant arthroplasty procedure utilizing silicone-based joint implants was the hopeful solution to this complex problem. After years of clinical experience, however, it has unfortunately become apparent that the silicone implant is not the panacea that many had hoped it would be. Although patient satisfaction has generally been good, complications such as material and structural failure, foreign body reaction, and short implant life span have forced many surgeons to reconsider its use. However, for a very select patient population implant arthroplasty may still be an acceptable alternative. Before the development of the silicone implants, the only surgical alternatives available for the "unsalvageable" joint were arthroplasty and arthrodesis. Both these joint destructive procedures had their own individual inherent complications and problems. The development of the silicone implants was an effort to avoid these complications and to try to provide the patient with a functional and cosmetic alternative. The implant arthroplasty is by definition a joint destructive procedure. However, when utilizing the total joint implant, the patient is provided with a spacer to retain hallux length and functional motion for the first MPJ. This chapter specifically addresses the implant arthroplasty as it is applied to the first MPJ. The bulk of the discussion relates to the total joint implant, although the hemi-implant is also discussed. Implant materials and designs are explained, as are the specifics of the most commonly used implants. Indications, criteria, objectives, and technical aspects of the procedure and postoperative care are also discussed, along with complications inherent to the implant arthroplasty.