Why The Flexor Digitorum Longus Transfer Offers Effective Hammertoe/Claw Toe Correction

Patrick DeHeer DPM FACFAS

Sometimes the procedures that we perceive as the simplest are those fraught with the most peril. Surgeons often think of hammertoe surgery as such a procedure, regardless of the type. Both arthrodesis and arthroplasty come with baggage and substantial complications that surgeons often downplay because, after all, “it is just a toe.” Tell that to the person who owns that toe and see if he or she feels the same way.

One approach for the treatment of flexible and, in many cases, semi-rigid hammertoe/claw toe deformities that yields very good, consistent results with much lower complication rates is the flexor digitorum longus tendon transfer. (Note: I do not use this for mallet toe deformities. For the flexible or semi-rigid mallet toe, a simple flexor digitorum longus tenotomy from the plantar distal interphalangeal joint skin crease will provide excellent results with a minimally invasive approach.)

The flexor digitorum longus transfer or Girdlestone Taylor procedure is underappreciated and underutilized in my opinion. Over my career, it has become my first line procedure for non-rigid hammertoe/claw toe deformities. I like the simplistic elegance of it with the conversion of a deforming force into a corrective force. I believe the underutilization stems from a lack of understanding of the procedure and technique, inadequate deformity evaluation and procedural habit.

When a patient presents with a symptomatic hammertoe/claw toe deformity, one must methodically evaluate the deformity to decide the most appropriate treatment. Really, the bottom line is the flexibility of the deformity. Does it reduce with loading of the forefoot? If the answer is yes, then clearly one should consider the flexor digitorum longus transfer if conservative therapy has failed or is not warranted. If the deformity is rigid, then the flexor digitorum longus transfer is not an option. The approach in this case is a discussion for another time.

The real complexity lies in the semi-rigid deformity and the answer depends upon the degree of rigidity. This is a very subjective finding that is often based on clinical experience. This complicates the use of the flexor digitorum longus transfer because I think the default for a semi-rigid deformity is arthrodesis or arthroplasty even though a flexor digitorum longus transfer may still be a better choice. Your first thought should be: is this semi-rigid deformity flexible enough for a flexor digitorum longus transfer?

A Guide To Surgical Technique

The technique for a flexor digitorum longus transfer can be one of two approaches: a three-incision combined plantar-dorsal approach or a one-incision dorsal medial approach. I prefer the former single incision approach and will discuss it.

I make the incision along the dorsal medial portion of the toe, extending from the base of the proximal phalanx to as far distal as possible without intruding upon the toenail. I then use sharp and blunt dissection to reach the plantar aspect of the distal interphalangeal joint. I use small sharp-tipped Iris scissors to open the plantar medial aspect of the distal interphalangeal joint. By opening the scissors, you will expose the flexor digitorum longus tendon.

Then clamp the tendon with a small hemostat just proximal to the insertion into the base of the distal phalanx. I completely cut the tendon distal to the hemostat with the Iris scissors from medial to lateral. Then mobilize the tendon medially to the base of the proximal phalanx. At this point, one can transfer the tendon dorsally from medial to lateral beneath ///a channel you create under the extensor complex via a 15-blade. The other option is to split the flexor digitorum longus tendon in half and transfer the lateral arm beneath the proximal phalanx plantarly and bring the medial arm around the medial side to wrap around the base of the proximal phalanx circumferentially. The only time I utilize the latter approach is when a transverse plane deformity exists at the metatarsophalangeal joint (MPJ). The splitting of tendon allows toggling of the proximal phalanx at the MPJ level.

For the medial to lateral passage of the whole tendon, I use a second small hemostat from lateral to medial to grab the tendon and pull it laterally. I will then dorsiflex the ankle to 90 degrees while manually reducing the proximal interphalangeal joint, allowing for correct tensioning of the transfer. It helps to have an assistant hold the foot to free up one of your hands to then clamp the tendon just lateral to the proximal phalanx under the correct amount of tension with a small hemostat. I secure the transfer with 3-0 Vicryl pulley-type sutures with one vertical and one horizontal suture. Laterally trim the excess tendon flush, being careful not to cut the suture.

Flush the area and close it with 4-0 nylon horizontal mattress sutures. I think it is critical to splint the toe with 1-inch Kling to the adjacent toe or toes.

Postoperatively, the patient is weightbearing in a surgical shoe unless other concurrent procedures dictate otherwise. At the first week postoperative visit, redress the toe in a similar manner, continuing the splinting. At the second week postoperative visit, remove the sutures and splint the toe with 1-inch Coban to the adjacent toe or toes. At this point, the patient may wear a gym shoe or clog type of shoe. I will splint the toe for four to six weeks postoperatively.

One interesting postoperative finding is the stiffness that occurs at the proximal interphalangeal joint, which I have never seen reported in the literature and I am beginning to study. This stiffness is what I believe allows this procedure to be an option for the semi-rigid deformity. I have never been able to figure out why it occurs but it does.

I have long thought that when you can avoid bone work on a hammertoe/claw toe deformity, the results are more reliable and complication rates are lower. The flexor digitorum longus tendon transfer procedure allows for this type of correction. Consider it when evaluating patients who present with symptomatic flexible or semi-rigid hammertoe/claw toe deformities. I think you and your patients will be pleased with the results. Be well and stay diligent.

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