May 2011

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.

Can A Medical Food Improve Sensation In Patients With DPN?

By Brian McCurdy, Senior Editor

A new study in Reviews in Neurological Disorders notes that patients with diabetic neuropathy may achieve improved cutaneous sensation by taking a combination of L-methylfolate, methylcobalamin and pyridoxal 5′-phosphate (Metanx, Pamlab).

   Researchers studied 20 patients with type 2 diabetes who took Metanx twice a day for four weeks and then once a day for 48 more weeks. The study says patients experienced statistically significant improvements in tactile and discriminatory static testing at the left and right great toe and in the heel. Authors noted the greatest improvement occurred between baseline and one year of treatment.

   The combination of L-methylfolate, methylcobalamin and pyridoxal 5′-phosphate provides patients with the benefits of increased nitric oxide production and increased flow mediated dilation, according to lead study author Mackie Walker, Jr., DPM. He says the supplement improves endothelial function, addressing the postulated underlying pathophysiology of diabetic peripheral neuropathy.

   When one considers the true cost of the symptomatic treatment medication regimes, such as pregabalin (Lyrica, Pfizer) and duloxetine (Cymbalta, Eli Lilly), Dr. Walker says Metanx is very affordable.

    “Since diabetic peripheral neuropathy is the leading cause of amputation, the opportunity to reverse or even slow down the progression of this process is of tremendous benefit to the cost burden of diabetic peripheral neuropathy to the healthcare system overall,” says Dr. Walker, who practices in the Podiatry Division at Carolina Musculoskeletal Institute in Aiken, S.C.

   Dr. Walker says patients tolerate Metanx as well as placebo. “Of the literally thousands of prescriptions I have written for Metanx, I can count on one hand the number of patients who could not tolerate it,” he adds.

Are Hammertoe Implants More Effective Than Arthroplasty Or Arthrodesis?

By Brian McCurdy, Senior Editor

Foot and ankle surgeons have various options at their disposal to correct hammertoe deformities. An abstract presented at the recent ACFAS conference compares interpositional implant arthroplasty, arthroplasty and arthrodesis for treatment of second hammertoe deformities. The authors note it is the first study to compare all three techniques.

   Researchers compared preoperative and postoperative second PIP joint angles in patients who underwent second proximal interphalangeal (PIP) joint correction from January 1998 to December 2008. The patients included 39 patients (45 cases) who underwent arthroplasty, 34 patients (43 cases) who underwent arthrodesis and 41 patients (48 cases) who received interpositional implant arthroplasty.

   In the arthroplasty group, authors note the average anteroposterior (AP) PIP joint angle was 8.2 degrees preoperatively and 11.4 degrees postoperatively while the lateral pre-op PIP joint angle was 46.9 degrees in comparison to 31.5 degrees postoperatively. The abstract notes the revision surgery rate was 37.8 percent.

   The study notes the average PIP joint angle for the arthrodesis patients measured 7.2 degrees on pre-op AP radiographs in comparison to 5.4 degrees postoperatively. Authors note the average PIP joint angle on lateral radiographs for this group was 46.4 degrees preoperatively in comparison to 24.7 degrees post-op. There was a revision surgery rate of 14.6 percent in this group.

   Finally, in the implant group, the AP radiographs of the PIP joint angle showed an average of 7.8 degrees preoperatively and 1.3 degrees postoperatively. The lateral radiographs of the PIP joint angle were 49.1 degrees pre-op in comparison to 24.2 degrees post-op, note the researchers. The authors say 10.4 percent of patients in this group had revisional surgery.

   The authors conclude that while arthroplasty, arthrodesis and implants can significantly improve pain and correct hammertoe in the sagittal plane, only the implant group showed significant correction of the deformity in the axial plane.

    “Hammertoe implants offer the best of both worlds,” notes lead study author Lowell Weil Jr., DPM, MBA, FACFAS. He says the implants provide stability to the toe like an arthrodesis would yet implants also offer some flexibility like an arthroplasty. “We call it an ‘arthroflexodesis.’”

   Dr. Weil has found less swelling postoperatively with implants compared to arthroplasty, attributing that to the stability of the procedure. He notes an implant also maintains a better length of the toe in comparison to arthrodesis or arthroplasty.

   Patients tolerate implants well, according to Dr. Weil, the Fellowship Director of Weil Foot and Ankle Institute in Des Plaines, Ill. “Unlike implants of larger joints, there is far less stress in the toes and less chance of implant irritation or wear,” notes Dr. Weil.

In Brief

Smith & Nephew announces Exogen™ Connects, a free service that helps patients more easily adhere to their Exogen Ultrasound Bone Healing System treatment plans via treatment reminders and tips for healthy living.

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