May 2011

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Study Finds Good Long-Term Results With First MPJ Implants

By Brian McCurdy, Senior Editor

A n abstract presented at the recent American College of Foot and Ankle Surgeons (ACFAS) Annual Scientific Conference notes good long-term results with a double-stem silicone first MPJ implant with titanium grommets.

   The authors reviewed the medical records of 63 consecutive patients who underwent total first MPJ implant arthroplasty from January 1979 to December 2002 with an average interval follow-up of 86.7 months. Employing the American Orthopaedic Foot and Ankle Society Hallux-Metatarsophalangeal Interphalangeal Scale (AOFAS HMIS) scale, researchers defined a successful outcome as complete relief of the chief complaint and patient satisfaction after 24 months of post-op follow-up. The study authors determined a success rate of 85.9 percent.

   Ten of 63 patients experienced complications in the perioperative period, including five ulcerations, three unresolved cases of neuritis and two incisional dehiscence complications. The study authors noted 13 cases of surgical revision at an average of 5.1 years post-surgery. Nine patients had worn or failed implants that were replaced. Four patients had to have implants removed and two of these patients required first ray amputation, according to the abstract.

   Lead study author Lowell Scott Weil, Sr., DPM, FACFAS, notes that 40 years ago, when silicone implants were introduced, many of the failures resulted from improper indications.

    “Since the advent of titanium grommets to protect the silicone from abrading and causing detritic synovitis, hinged toe implants have been very successful in retaining motion for those patients who do not want a fusion,” explains Dr. Weil.

   The ideal indication for first MPJ implants is hallux rigidus with a normal intermetatarsal angle and long first metatarsal, according to Dr. Weil. He notes hemi-implants are usually indicated in patients between the ages of 35 and 45 with articular loss on one side of the joint that is less than 50 percent coverage of the joint. When there is severe cartilage loss on both sides of the joint, he notes an arthrodesis or hinged toe implant offer the best long-term success.

   Early complications after a hinged toe implant are not as frequent as malunion and non-union after arthrodesis, according to Dr. Weil, the Medical Director of the Weil Foot and Ankle Institute in Des Plaines, Ill.

   Dr. Weil adds that it is common in his experience to use first MPJ implants for female patients 45 and older who refuse fusion.

   Lawrence DiDomenico, DPM, FACFAS, applauds the study performed by the Weil Foot and Ankle Institute. He does not often use first MPJ implants, citing their lack of predictability. Although the implants may look good in feet with hallux rigidus and hallux limitus, he says it has been his experience that biomechanical problems may prevent the implants from working well long term. However, Dr. DiDomenico adds that if you have properly addressed biomechanical correction, “these (first MPJ) implants will work relatively well.”

    “When used for the proper indications, implants can be very successful in reducing pain of the first MPJ and rendering a long survival rate,” says Dr. Weil, who is a consultant and has developed first MPJ implants for Wright Medical Technology and Tornier Orthopedics.

   Dr. Weil also notes the recent emergence of pyrocarbon, a new material with qualities similar to cartilage. He says pyrocarbon is currently undergoing testing for resurfacing of the first metatarsal head in patients with stage 1 or 2 hallux rigidus.

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