Current Insights On First MPJ Implants

Darryl J. Martins, DPM

Recent years have seen the rise of innovative implants for first metatarsophalangeal joint (MPJ) pathologies. Accordingly, this author offers an intriguing review of the current literature on first MPJ arthroplasty.

Over the past decade, there have been steady improvements for first metatarsophalangeal joint (MPJ) pathologies. These include first MPJ hemi-implants, resurfacing of the first MPJ and two- or three-component implants. With the growing number of companies entering the foot and ankle market, it can be overwhelming to keep up with such data and material. Accordingly, let us take a closer look at the literature on these implants.

   Metatarsophalangeal joint implants have been adjunctive treatments for the podiatric physician for over 60 years. After decades of design improvements, material enhancements, biomechanical studies and a better understanding of patient candidacy, the ideal implant is still under question. Aside from improvements in design and materials, the greatest factor has been the quality of controlled trials available for the foot and ankle surgeon to assist in decision making. There is still a lack of quality level 1 or 2 evidence-based medicine (EBM) studies. However, level 3 and 4 EBM studies can be valuable tools.

   When discussing the first MPJ, it is essential to have a strong understanding of the different pathologies and proper indications for implant use. Drago and colleagues developed one of several grading classifications.1 This classification includes four different stages.

Stage 1: Functional hallux limitus with minimal adaptive changes

Stage 2: Joint adaptation, development of proliferative, destructive joint changes

Stage 3: Joint deterioration, arthritis, established arthrosis

Stage 4: Ankylosis

   Surprisingly, the option of joint arthroplasty is not in the currently published clinical practice guidelines.2 As of September 2009, the Academy of Ambulatory Foot and Ankle Surgery did not include the use of any type of implant alone for either hallux limitus or hallux rigidus. Keller arthoplasty in conjunction with an implant is the final recommendation before first MPJ fusion. However, in the past 10 years, there have been 15 medical device companies that have filed a patent pending for their design of a first MPJ implant and there has only been one recall.3

Assessing The Study Results For The BioPro Great Toe Hemi-Implant

Great Toe Hemi-Implant (BioPro). In 1994, Townley and Taranow reviewed the use of a metallic resurfacing hemiarthroplasty in 279 cases over a 40-year period.4 Indications for surgery included hallux rigidus, rheumatoid arthritis and degenerative changes associated with hallux limitus and bunion deformity. The study authors noted that follow-up, which ranged from eight months to 33 years, showed good to excellent results in 95 percent of the cases.

   In 2010, Salonga and colleagues reviewed 79 first MPJ hemiarthroplasties in 23 men and 53 women.5 The mean age of the patients in the study was 59.6 years of age and the mean follow-up was 2.91 years. The indications for implantation were failure of conservative treatment, chronic first MPJ pain, degenerative osteoarthritis of the first MPJ and decreased ambulation and functional status. The advantages included minimal postoperative debilitation and reliable pain relief, according to the authors.

   The mean postoperative American College of Foot and Ankle Surgeons (ACFAS) Universal Evaluation score was 94.00.5 The researchers found statistically significant increases in first MPJ dorsiflexion and plantarflexion. They also saw decreases in the first intermetatarsal angle and metatarsal elevatus but noted that these were unlikely to be clinically significant. Post-op care entailed seven to 10 days in a bandage and post-op shoe with a subsequent return to walking.

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