Emerging Concepts In Hammertoe Surgery

Although podiatrists commonly perform hammertoe surgery, the procedure can be fraught with complications. Accordingly, this author shares pearls on internal fixation, soft tissue management and metatarsal surgery, and offers pertinent principles on ensuring postoperative success.

   Hammertoe surgery has always been considered one of the “easier” surgeries when it comes to foot surgery as a whole. For those of us who can think back to when we first started in residency, it was hammertoe surgery procedures in which we initially got our chance to hold a scalpel and perform surgery. This is ironic as hammertoe surgery, in reality, can be the most difficult foot surgery when it comes to achieving predictably good results. We can all think of incidences in which we were humbled by “simple hammertoe surgery.”

   Some of the more challenging aspects of hammertoe surgery include management of prolonged swelling, stiff toes, “pencil straight” toes, recurrence of deformity and lack of toe purchase to the ground just to name a few. Needless to say, the profession is still looking for a way to get predictable, reproducible, good results in the long term.

   Since the hammertoe deformity is very complicated, there is no one answer that can address all types of hammertoes. In podiatry school, we learned about biomechanical etiologies of hammertoes such as flexor and extensor substitution. We also learned an algorithm for surgical treatment based on the etiology. I personally do not put much faith in that as hammertoe deformities are complex and sometimes can be multifactorial in etiology.

   To that end, when it comes to hammertoe surgery, I believe one has to fix the deformity of the bone and balance the soft tissues. That is it in a nutshell. However, this is easier said than done.

   Generally speaking, the term hammertoe describes a wide variety of toe deformities although other more descriptive terms include claw toe, mallet toe, crossover toe and clinodactyly. All hammertoes are not created equal. I have found that the second and fifth toes are the most difficult to treat with consistent good results.

   The fourth toe seems to swell the most after surgery, which can be aggravating for both physicians and patients. Transverse plane deformity of the toe can be present along with the more common saggital plane contractures. The fourth and fifth toes may have adductovarus deformity as well and can sometimes deform after surgery if one does not address the influence of the long flexor tendon.

   So why are hammertoes so difficult to treat surgically? Well, it is all about the soft tissues as opposed to the bone. If we put two ends of bone together and stabilize them, the bone will heal that way. However, if there are deforming forces on the toe from soft tissues (including tendons, capsule and ligaments) that affect the bones, then the toe is going to deform over time. We have all seen internal hardware break in a toe due to persistent forces on the toe. In addition, after the amputation of a great toe, the lesser toes will often adduct and claw due to tendinous imbalance. These examples are a testament of how deforming these soft tissue forces can be.

What You Should Know About Internal Fixation And Decompression Techniques

   The most notable recent changes in hammertoe surgery involve internal fixation techniques and decompression techniques by shortening the metatarsal segment.

   For the past 30 years or more, Kirschner wires have been the method of choice for fixation of toes. It is technically simple to “pin the toe” and, if necessary, the K-wire can cross the metatarsophalangeal joint (MPJ) to stabilize that joint as well.

   Drawbacks of this fixation include the possibility of pin tract infection (which, in my experience, is quite rare), and the psychological component for the patients having pins protruding out of their toes. There is always the fear of stubbing the foot and pushing in the pins. There is also the chance of snagging the pins and pulling them out by accident. Crossing the K-wire across the MPJ can also cause stiffness in that joint.

   Lesser MPJ limitus can be a source of pain. To minimize that risk, I usually pull back the K-wire to the base of the proximal phalanx at three weeks to have it only in the toe. One notable exception is for a pan metatarsal head resection. With these procedures, I leave the K-wire across the joint for at least six weeks.

   Newer methods for bone fixation include resorbable rods, allograft bone pins, screw fixation, bone staples, intramedullary K-wires and one- and two-piece metallic fixation systems such as the Smart Toe (MMI) and the StayFuse (Tornier).

   The new fixation devices and techniques were designed in part to eliminate the need for percutaneous fixation but newer is not always better. For certain applications, some of the newer fixation techniques may have an advantage. For example, when the patient has a simple hammertoe deformity on the second toe and only a sagittal plane deformity at the proximal interphalangeal joint, an intramedullary fixation technique can be advantageous.

   However, if there is significant deformity in the toe including dislocation at the MPJ, employing an intramedullary fixation device may not be the best choice unless you combine this with other procedures. One cannot address the more proximal joint with the fixation device. In addition, if you are concerned about the patient developing a mallet toe after a proximal interphalangeal joint fusion, then a percutaneous K-wire is a better choice because one can maintain the distal interphalangeal joint in a rectus position for six weeks.

   When it comes to hammertoes that are caused by neurologic disorders, such as Charcot-Marie-Tooth disease, a small diameter cannulated screw is a good option because it can stabilize both the proximal and distal interphalangeal joints. This will prevent the toe from developing a mallet toe deformity.

   Using the single and two-piece metallic fixation devices would negate the need for percutaneous fixation. The main drawback, however, is if one would need to remove these devices. Since these implants are completely buried in bone, the surgeon would need to perform significant destruction of bone to remove them. One scenario for removal might be a metal allergy that comes to light after implantation.

Pertinent Insights On Managing Soft Tissues

   When the MPJ is involved with deformity in a hammertoe, then everything changes when it comes to surgical procedure(s). It is no longer about arthrodesis versus arthroplasty of the proximal interphalangeal joint. It is now all about managing soft tissues that influence the position of the toe.

   One can obtain relaxation of soft tissues by performing soft tissue procedures such as extensor hood recession and dorsal capsulotomy of the MPJ. Sometimes, the surgeon may perform a more aggressive capsulotomy on the side of the joint where the toe deviates (usually medially in the second toe) and a capsulorrhaphy on the opposite side of the joint. This maneuver can be successful in milder deformities.

   In more severe deformities, one may consider a flexor to extensor tendon transfer. With this procedure, the surgeon may split the tendon into a medial and lateral arm, and then manipulate the arms like a yoke in order to “balance the toe” and resolve the deformity. In addition, repair of the plantar plate can help relocate a subluxing MPJ.

Shifts In Thinking On The Impact Of Metatarsal Surgery On Hammertoes

   The aforementioned procedures involve soft tissue maneuvers to relax a toe. Through a metatarsal shortening procedure, one can decompress the metatarsophalangeal joint to allow for relaxation of the toe, a technique that is becoming more popular in recent years. Back when I was in residency training, metatarsal osteotomies for the central rays were basically taboo unless there was a severe deformity, which was usually due to prior failed surgery on the metatarsal or trauma. I learned not to interfere with the metatarsal parabola at all costs.

   The dogma of metatarsal surgery has changed. Surgery on the metatarsal for complex hammertoe correction is now commonplace in my practice.

   For transverse plane deviated hammertoes, the surgeon not only shortens the metatarsal but he or she may translocate the metatarsal head on the transverse plane to reduce the deformity. The metatarsal head shifts in the same direction of the deformity (usually medially for a crossover type deformity). In bunion surgery, the metatarsal head shifts over the sesamoid apparatus. In lesser metatarsal surgery, the metatarsal head shifts over the long flexor tendon and plantar plate.

Key Principles To Facilitate Optimal Post-Op Results

   Since the goal of hammertoe surgery is to reduce the osseous deformity and neutralize soft tissue imbalances that are contributing to the deformity, there are a few tenets of hammertoe surgery that I tend to follow.

   • Arthrodesis of the proximal interphalangeal joint is generally preferable for toes two, three and four.
   • Arthroplasty is preferable on the fifth toe and sometimes on the fourth toe if one performs it as a stand-alone procedure.
   • If I am repairing the second and third toes, I will tend to do all the toes. Otherwise the fourth and fifth toes will appear to be hammered due to the straightness of the second and third toes.
   • Keep the toes long. Remove as little bone as possible in order to allow the flexor tendon to have a better lever arm for toe purchase.
   • Patients should have internal fixation for six weeks if possible to allow for fusion or an asymptomatic pseudoarthrosis.
   • Simple arthroplasties of toes without fixation are fine for geriatric patients who have little activity or demand. For example, in this instance, function and cosmesis are less of a concern in comparison to being able to wear a closed-in shoe without pain and/or fearing an ulceration to develop on the toe.
   • For complex hammertoes with multi-plane deformities, perform a stepwise surgical approach utilizing the Kelikian push-up test to determine the need for further work. This includes fusion preparation at the proximal interphalangeal joint, extensor hood recession of the MPJ with capsulotomy, metatarsal osteotomy and flexor to extensor transfer if needed. When do you know you are done? When you load the foot (Kelikian push-up test) and the toe does not drift into deformity.

   Other things to consider would be addressing disorders of the first ray such as hallux valgus, which may be influencing the lesser toes. One can address adductovarus deformity with derotational skin plasty and perform flexor tenotomies in the distal toe to eliminate flexible mallet toe deformity.

   I personally do not utilize flexor tenotomies on toes unless it is for a tip ulcer in a patient with diabetes or in a similar scenario. For such patients, it may be prudent to do a tenotomy in all of the lesser toes on the foot to prevent worsening deformity on the other toes over time.

   In addition, always remember that the extensor tendon is generally not the problem in a hammertoe. It is the flexor tendon and plantar plate that become dysfunctional. That is why a simple stab incision to the extensor tendon and capsule of the MPJ rarely fixes the hammertoe deformity in the long term.

In Conclusion

   It is difficult to discuss everything regarding the different techniques and modifications of hammertoe surgery as one could probably dedicate an entire textbook on the topic. Of all the common foot surgeries that we do, there is more decision making and overall complexity in hammertoe surgery than in any other surgery.

   Just remember that the goal is simple: the toe needs to be straight and pain-free in a shoe. Remember to address all the soft tissues that are influencing the toe and eliminate those deforming forces. A postoperative Betadyne dressing or splinting the toe in a corrected position following the surgery is not going to work in the long term for maintenance of correction. Pinning the toe into correction across the metatarsophalangeal joint will not last after one pulls the pin if the deforming soft tissue forces do not abate.

   If you follow all the steps outlined above, you should have a rectus toe that will not tend to deform with the Kelikian push up test or with weightbearing after surgery. If you get to that point, then you will know that you nailed it.

Dr. Fishco is board-certified in foot surgery and reconstructive rearfoot and ankle surgery by the American Board of Podiatric Surgery. He is in private practice in Phoenix. He is also a faculty member of the Podiatry Institute.

For further reading, see “The Top Eleven Pearls For Hammertoe Surgery” in the April 2002 issue of Podiatry Today, “How To Handle Complications Of Hammertoe Surgery” in the September 2005 issue or “Hammertoe Surgery: Can Emerging Advances In Fixation Have An Impact?” in the September 2008 issue.

To access the archives or get reprint information, visit www.podiatrytoday.com.