Can A New Implant Lead To Easier Hammertoe Arthrodesis?

Patients having hammertoe arthrodesis have had to undergo fixation with K-wires that can cause complications including pin tract infection. However, a new implant may obviate the need for K-wires and provide adequate correction. The Smart Toe™ Intramedullary Memory Implant was specifically developed for hammertoe arthrodesis and is composed of nitinol (Memometal® Alloy Ti-Ni), according to the manufacturer MMI-USA, Inc. Since the implant is one piece, no connection is required. There is no post-op implant exposure and no disruption of healthy joints. The company says the implant eliminates the risk of pin tract infection. MMI says the compressive feature reduces the occurrence of nonunions and the implant’s shape resists rotation. James McCarty, DPM, has been using the Smart Toe since September and has performed 30 to 40 hammertoe arthrodesis procedures with it. “They have all fused. They are all absolutely perfect,” emphasizes Dr. McCarty, who practices at Shores Podiatry Associates in Michigan. What Are The Advantages Over K-Wire Fixation? Dr. McCarty emphasizes the importance of correcting the entire hammertoe at once. As he points out, many surgeons use four to five 0.62 K-wires retrograde to the metatarsal head. However, he says 20 percent of those do not fuse and the angulation deforms the proximal interphalangeal joint (PIPJ). Dr. McCarty notes that the surgeon must keep the K-wire in the metatarsal to allow correction, which reduces once one removes the K-wire. If the surgeon pulls out the K-wire and the toe is not straight, the patient will not be happy, he adds. Dr. McCarty says the Smart Toe implant offers a viable alternative. “The (Smart Toe) product is extremely simple to use,” maintains Dr. McCarty. Craig Breslauer, DPM, concurs, noting that for many years, surgeons had to leave in the percutaneous K-wire for fixation. Dr. Breslauer has been using the Smart Toe implant for the last two months and has seen positive results. “Patients have been very pleased with the product,” notes Dr. Breslauer. Since there is no motion around a K-wire, there is much less swelling with the Smart Toe, according to Dr. Breslauer, who practices at South Florida Orthopaedics and Sports Medicine. He says the implant facilitates rigid construction of the interphalangeal joints and patients feel better in the long term because the Smart Toe remains present while they heal. Other Pertinent Points The Smart Toe implants are available in lengths of 16 and 19 mm and with a 1.2-mm thickness, according to the manufacturer. The company says the implant’s opening is from 2 to 5.5 mm at the proximal position and the opening is from 3 to 6 mm at the distal site. MMI notes the implants are packed in individual sterile boxes and should be stored in a freezer prior to use. Dr. Breslauer does note a contraindication for the Smart Toe implant. He will not use it in cases of more advanced digital contraction in which the patient requires a tentotomy or capsulotomy, as one cannot temporarily fixate the metatarsophalangeal joint (MPJ).