April 2012

Study Raises Questions On Partial First Ray Amputation In Patients With Diabetes

By Danielle Chicano

A recent systematic review found that one in every five patients with diabetes and peripheral neuropathy undergoing a partial first ray amputation subsequently required a more proximal amputation.

   The systematic review, which was recently presented as a poster at the American College of Foot and Ankle Surgeons Annual Scientific Conference, was based on five peer-reviewed studies that met the inclusion criteria and looked at the rate of re-amputation following partial first ray amputation in patients with diabetes and peripheral neuropathy. Out of a total of 435 patients who had partial first ray amputations, the review authors found that nearly 20 percent (86 patients) had to have a subsequent, more proximal re-amputation.

   The researchers concluded that “a partial first ray amputation may not represent a durable, functional or predictable foot sparing amputation.” While citing the need for further research in this area, they suggested that performing a more proximal amputation, such as a more balanced transmetatarsal amputation, initially may be more beneficial in this patient population.

   Valerie Schade, DPM, AACFAS, notes that the “vast majority” of her patients with diabetes who have had a partial hallux to partial first ray amputation eventually require a more proximal amputation within one to two years after the initial procedure. She notes that patients with a partial first ray resection typically re-ulcerate under the lesser metatarsal heads or the dorsum of the lesser digits.

   “I feel that it is in the best interest of the patient at that point to provide a stable, plantigrade foot, which is at minimal risk of re-ulceration and further amputation,” explains Dr. Schade, the Chief of the Limb Preservation Service and Director of the Complex Lower Extremity Surgery and Research Fellowship at Madigan Healthcare System in Tacoma, Wash. “The primary limitation of re-amputation would be the need for closure of the plantar defect created from excision of a plantar ulceration.”

   Monica Schweinberger, DPM, concurs that avoiding further amputation is in the best interest of the patient because of possible complications involved in multiple surgeries and the adverse affects of chronic wounds on patients’ mental health.

   “If a single, more proximal amputation could reduce the length of recovery and get patients back to their lives sooner, it might be a better option in some cases,” explains Dr. Schweinberger.

   Patients with neuropathy and evidence of increased pressure (i.e. callus formation) under neighboring metatarsal heads, those with severe forefoot deformity, those with significant tissue loss that may impair incision closure, or those with multiple forefoot ulcerations or one or more previous digital or ray amputations may fare better with a more proximal amputation rather than a first ray amputation, explains Dr. Schweinberger, who is affiliated with the Cheyenne Veterans Affairs Medical Center in Cheyenne, Wyo.

   Both Drs. Schweinberger and Schade agree that an orthotic with extra depth and a rocker bottom sole can help facilitate postoperative healing after a partial first ray amputation.

   Additionally, Dr. Schweinberger notes, “an orthotic with a 3-degree rearfoot varus post, metatarsal padding, a filler in the area of the missing hallux and accommodation under any areas of callus formation may help reduce forefoot pressure and improve durability of a partial first ray amputation.”

Is Plate Fixation Better Than Screw Fixation For First MPJ Arthrodesis?

By Brian McCurdy, Senior Editor

A recent study in the Journal of Foot and Ankle Surgery, which compared several methods of fusion for first metatarsophalangeal joint (MPJ) arthrodesis, found that plate fixation alone leads to the fewest nonunions.

   The authors conducted a retrospective analysis of first MPJ arthrodesis procedures performed at their institution between January 2000 and April 2010. The retrospective review assessed 72 arthrodesis procedures. Twenty-four cases involved fixation with one oblique lag screw, 21 were fixated with two crossed lag screws, 13 were fixated with a low contour dorsal plate and 14 were fixated with a plate and a plantar lag screw. The study notes that single screw fixation resulted in a fusion rate of 71 percent, in comparison to a 100 percent fusion rate in patients who only had plate fixation. The study authors did emphasize the need for further research with larger numbers of patients.

   For several years, Patrick DeHeer, DPM, has used both a compression 4.0 screw and dorsal plate fixation, saying the screw provides compression and the plate provides neutralization. “To just use one or the other is an inferior form of fixation compared to the combination of the two,” he asserts.

   Likewise, Lawrence Fallat, DPM, has found the most stable construction for first MPJ fusion to be a combination of one or two interfragmentary screws across the joint with a dorsal plate. He notes the plate can be a tubular neutralization plate or locking plate. He says the screws ideally should be 3.5 cortical screws, although one can achieve compression with a 4.0 cancellous screw. Dr. Fallat adds that the type of plate may not be as important as proper joint preparation.

   As Dr. DeHeer notes, locking plates with a compression component have been a significant advancement. When surgeons compress the arthrodesis site with an external device and then apply a locking plate under compression, he says this provides the same result as a compression screw and neutralization plate. This is a significant improvement of more bone to bone contact without the large 4.0 compression screw crossing the fusion site, according to Dr. DeHeer, a Fellow of the American College of Foot and Ankle Surgeons who practices at Hoosier Foot and Ankle in Carmel, Ind.

   Dr. Fallat says using a combination of interfragmentary screws and a plate provides compression and is better able to resist the axial load that occurs when the patient starts walking.

   “When failure of fixation occurs, it can occur with either a tubular or locking plate. Screws can be displaced and either plate can break,” says Dr. Fallat, a Fellow of the American College of Foot and Ankle Surgeons and the Director of the Podiatric Surgical Residency Program at Oakwood Healthcare System in Dearborn, Mich.

   Dr. Fallat says one can achieve the best results with good joint preparation and an autogenous graft (less than 2 cm) if necessary.

   Dr. DeHeer adds that locking plate/screw systems that are joint specific and also utilize an external compression system are very user friendly, and provide rigid fixation utilizing the most up-to-date technology.

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