Learning From Failed Talonavicular Fusions
Isolated fusions of the rearfoot have long been a choice of many podiatric foot and ankle surgeons for conditions such as coalitions, arthrosis and symptomatic flatfoot deformities. Persuasive arguments can be made for fusion of the calcaneocuboid, subtalar or talonavicular joints, especially when it comes to deformities such as the symptomatic flatfoot. While each of these procedures provide certain benefits for surgeons, they can present their own unique intraoperative and postoperative challenges as well. With this in mind, I would like to share my thoughts as to why my talonavicular (TN) fusions have had far less successful outcomes than my other isolated rearfoot fusions. Originally, I simply labeled this arthrodesis as inferior and gravitated toward other procedures. However, after reviewing the majority of my cases and reading authors who prefer this technique, I have changed my opinion. Many of the unsuccessful outcomes I have had have come from identifiable and correctable problems. All surgeons will agree that numerous factors can affect surgical outcomes. The patient’s health (mental and physical), social habits (i.e., smoking), occupation and compliance can all have a positive or negative impact. In reviewing my surgical results, I have divided the outcomes into short- and long-term failures. These are general categories and, naturally, several factors can work together to affect surgical outcomes. The following factors are what I feel I could specifically change to enhance the chances of a more successful case. Poor patient selection is one of the most vague areas of failure. However, I have found less than stellar results after performing the talonavicular arthrodesis in an extremely obese patient. Even when I have addressed the ankle equinus surgically and performed adjunctive procedures, such as a first metatarsal-cuneiform arthrodesis, I have still had significant complications from persistent valgus deformity of the heel to abduction of the forefoot. Despite the fact that intraoperative alignment and immediately postoperative alignment are satisfactory, many of my cases progress to further planus deformities. In many cases in which the patient is obese, I often prefer a triple arthrodesis. Although this is a larger procedure with a more complex postoperative course, I feel these particular patients receive a better long-term outcome with the more extensive surgery. It is vitally important to evaluate the activity level of the patient prior to any rearfoot arthrodesis. Even if the surgery is properly indicated and performed, a fusion of the rearfoot can significantly alter function of the foot and ankle. Granted, these patients will most likely be experiencing significant pain preoperatively, but you must realistically discuss their expectations for the surgical outcome. In particular, these patients may need to consider occupational changes or changes in their athletic activity. Why I Prefer Joint Resection Over Curettage In Most Cases Joint preparation has been discussed numerous times over the past decade. Joint resection seems to have evolved slowly to more of an emphasis on curettage techniques. Although curettage is an excellent technique, I prefer a resection technique in most cases of talonavicular fusions for several reasons. • Resection ensures removal of cartilage to the level of bleeding cancellous bone. The natural shape of the talonavicular joint makes it difficult to remove cartilage adequately from the lateral aspect of the joint without an ancillary incision. Instead of resecting both aspects of the joint, I often prefer to resect the distal portion of the talar head and then proceed to curettage and drilling of the navicular component. • Performing resection shortens the medial column, which facilitates reduction of the flatfoot deformity. When you resect the distal portion of the talar head, you can reposition the TN joint and use the removed bone as an autogenous graft. • Resection facilitates fixation with compression staples or plates. Key Points About Ensuring Adequate Fixation Inferior fixation is actually a term that is open to interpretation. The majority of my TN fusions are adequately fixated in compliant patients but may be fixated inferiorly in noncompliant patients. The TN fusion, as a component of a triple arthrodesis, may be adequately held with a single lag screw. However, when performing the TN fusion as an isolated procedure, you need a second screw.