When An Ankle Fusion Fails
This author presents a revisional surgical approach to a failed ankle fusion in an obese 64-year-old patient.
Ankle fusion for end-stage ankle arthritis remains the time-tested standard of care although one could argue that the current standard of care is changing to total ankle replacement.
The ankle arthroplasty, however, does have its limits. The current relative contraindications to ankle arthroplasty include but are not limited to diabetes and obesity. This obese, diabetic population remains a challenge to treat, regardless of the surgical procedure of choice. The following case is an example of an obese patient with diabetes who had a non-union develop following an ankle fusion attempt and had subsequent revision fusion surgery.
A Closer Look At The Patient Presentation And Initial Surgery
A 64-year-old male with a body mass index of 45 presents with progressive pain at the right ankle and a previous history of ankle scope and loose body removal five years prior. His past medical history is otherwise remarkable for a history of tobacco abuse and moderately controlled diabetes. After an in-office physical exam, radiologic evaluation and counseling, I elected to attempt ankle fusion.
After employing a standard anterior incisional approach, I used osteotomes and curettes to prepare the fusion site. I subsequently filled the fusion site with off-the-shelf demineralized bone matrix constituted with bone marrow aspirate harvested from the lateral calcaneus. After placing a cannulated 5.0 mm titanium screw from the medial tibia into the lateral most aspect of the talus, I was able to achieve adequate positioning and compression. Finally, I added a locking titanium anterior fusion plate with 3.2-mm locking screws to the anterior aspect of the ankle joint. Joint stability was evident and intraoperative fluoroscopy verified the position of the joint.
The patient was pain-free and progressing to protected weightbearing at the third month until radiographs confirmed hardware failure at the plate-screw interface. All three of the screws purchasing the tibia failed. While this resulted in minimal displacement, the superior portion of the plate created a cortical notch as ground reactive forces created a response visible on the lateral radiograph. The patient then noted pain recurrence at the ankle joint circumferentially.
At this time, I utilized a bone stimulator and initiated a return to boot protection. Computed tomography (CT) confirmed a nonunion at six months. The joint maintained its position but his pain continued at the level of the ankle. After thorough office counseling with the patient, we elected for revision ankle fusion with hardware removal.
What The Revision Surgical Approach Entailed
This revision surgery again consisted of an anterior approach. After removing the visible hardware, the three broken screws remained within the tibia. I debrided the non-viable tissue down to bleeding cancellous bone. I again utilized demineralized bone matrix with bone marrow aspirate to fill any voids remaining post-debridement. Employing a more robust 7.0 headless cannulated screw helped set the position and gain compression. I also used a more robust titanium anterior locking plate with 5.5-mm locking screws and added bone morphogenetic protein to the anterior fusion site prior to performing standard closure.
After his revision surgery, the patient continued to utilize the bone stimulator. He discontinued tobacco use. He was non-weightbearing for 10 weeks prior to protected weightbearing. The patient’s most recent radiographs at five months show interval healing and he has no pain to date. He has transitioned to a brace and has been deer hunting with no problems.
Ankle fusion in an obese patient with diabetes who smokes can be difficult. Ultimately, tobacco cessation, the use of bone marrow aspirate, demineralized bone matrix, bone morphogenetic protein and increasing plate strength allowed a solid union to date. Assessing and maximizing the use of orthobiologics in at-risk patients may offer a greater chance at successful outcomes, particularly in difficult cases. As anterior locking plate options continue to evolve, choosing a robust plate and screw can offer improved stability in patients who are particularly at risk for an elongated healing period.
Dr. Bussewitz is a fellowship-trained foot and ankle surgeon who is currently in private practice in Iowa City, Iowa.