Can A New Ex-Fix Device Have An Impact In Deformity Correction?
The device is called the EZ Frame (Signal Medical Corp.). It is composed of a boot with adjustable straps, a rocker-bottom footplate, stainless steel posts, wire nuts, smooth wires and olive wires. The boot is connected to the footplate via telescoping carbon fiber rods. Additionally, one can remove the full-length tongue during dressing changes and adjust the positions of both the boot and the frame. Various sizes are available. The footplate also allows versatility in offloading ulcerated areas.
In a study performed on seven cadaver specimens and six polyurethane foam models, researchers created a midtarsal wedge osteotomy with a template. They placed an F-Scan pressure insole system (Tekscan) inside the osteotomy and used it to measure and record the pressure created across the osteotomy site after applying fixation. Researchers compared multiple ring external fixation with tension and compression versus the EZ Frame with tension and compression. The F-Scan results demonstrated superior compression strength across the osteotomy fixated with the EZ Frame.17 Researchers believe this superior compression results from the force vectors that are stabilized against the plantar plate apparatus during tensioning of the EZ Frame.
The EZ Frame, which was recently FDA-approved, also allows guarded weightbearing. There is a decreased learning curve for this frame as opposed to other external fixation devices. It is also available as a complete system, which reduces OR time.
Some of the indications for the EZ Frame include isolated rearfoot arthrodesis, midfoot arthrodesis/osteotomy, comminuted trauma and diabetic Charcot reconstruction. One may also employ this device for the majority of foot pathology that does not require fixation above the ankle.
Case Study: Treating A Patient With Severe PTTD
A diabetic patient presented with severe posterior tibial tendon dysfunction and pes plano valgus deformity. Surgeons performed a triple arthrodesis and applied the EZ Frame with four pins. The pins were located in the calcaneus, talus, navicular and across the metatarsals (see right photo).
The patient should remain non-weightbearing for up to six weeks. At this time, practitioners can remove the frame and place the patient in a below knee walking cast for approximately two weeks following serial radiographs. One can subsequently transition the patient into a CAM-Walker and eventually into regular shoe gear.
The obvious advantages to employing this modality for diabetic foot reconstruction are guarded weightbearing, enhanced stability and the preclusion of proximal pin sites.
Dr. Steinberg (pictured) is an Assistant Professor in the Department of Surgery at the Georgetown University School of Medicine in Washington, D.C. He is a Fellow of the American College of Foot and Ankle Surgeons.