Minimizing The Risk Of Failed Hammertoe Surgery

Johanna Richey, DPM, and Graham Hamilton, DPM, FACFAS

Hammertoe surgery is not without its complications as reportedly 17 percent of patients are dissatisfied with their post-op results. Accordingly, these authors review key anatomical points and essential biomechanical considerations to help ensure appropriate procedure selection and favorable post-op outcomes.

While hammertoe surgery is a common procedure performed routinely around the country, it has unpredictable results. According to 2003 data from the Centers for Medicare and Medicaid Services, there are 300,000 hammertoe surgeries performed annually with over 50,000 patients unsatisfied with the results.1

   This equates to approximately 17 percent of all hammertoe operations resulting in “unsatisfied” patients. Patients may complain their toes are too short, too long, too fat, too curved, too straight or too floppy.

   Coughlin and colleagues conducted the largest hammertoe study with 118 toes on 67 patients.2 Patients underwent evaluation at an average of five years following proximal interphalangeal joint (PIPJ) fusion with Kirschner wire fixation. Fusion of the PIPJ occurred in 81 percent of cases and 84 percent attained subjective satisfactory results.

   In a study of PIPJ arthrodesis, Lehman and Smith noted a 48 percent satisfaction rate without reservation with a peg-and-dowel technique.3 The rest were not completely satisfied with major reasons for postoperative dissatisfaction being toe angulation and incomplete relief of pain.

   It is clear that something as “simple” as a toe has significantly mixed and unpredictable results. What can we do to improve patient satisfaction? How do we improve surgical outcomes?

   First, it is imperative for foot and ankle surgeons to have a detailed understanding of digital anatomy as well as a solid conceptualization of the biomechanical forces acting on the digits. Perhaps the reason surgical outcomes are so unpredictable is not because the toes are so intricate or complicated, but is more due to a lack of an adequate physical exam. Without a thorough exam, one cannot identify the deforming forces and thus cannot appropriately plan surgery. It is essential to approach digital surgery with an attention to detail, an accurate knowledge of anatomic structures and how the biomechanical function and forces are transmitted and disrupted with surgical augmentation.

   There are many functional considerations one must explore in order to develop accurate and appropriate surgical planning or salvage if hammertoe surgery fails. We have divided these into three simple categories: anatomy/physiology, biomechanics (tendon balancing and foot type) and deformity considerations (flexible versus rigid, subluxed versus dislocated). We present two cases of hammertoe deformity correction with discussion of these functional considerations.

A Pertinent Primer On Digital Anatomy And Physiology

A detailed understanding of digital anatomy is essential to understanding the biomechanical relationships and forces that act on the digit. This becomes the crux of hammertoe surgery. As we begin to manipulate and augment these biomechanical relationships, we will eliminate, neutralize or create new deforming forces, which may later translate to deformity.

   Consider the four different surface planes of the anatomy: dorsal, plantar, medial and lateral. Then consider the orientation of how tendons cross these planes to conceptualize how the vector of force relates to movement through the digit. Where do the tendons cross the joints?

   Dorsally, the tendon of the extensor digitorum longus (EDL) splits into three tendon slips with the central portion inserting on the base of the middle phalanx. The medial and lateral slips converge into the terminal tendon to insert together at the base of the distal phalanx. All of the tendon insertions are covered by the extensor expansion, a fibro-aponeurotic sling. This sling then wraps around the digit and inserts on the plantar aspect of the digit at the base of the proximal phalanx.

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