Why K-Wires Are Still The Best Fixation Devices For Hammertoe

Intramedullary hammertoe fixation devices would appear to be an advancement in hammertoe surgery. I previously wrote a DPM Blog about the use of hammertoe devices.¹ There are apparent benefits of hammertoe implants, such as patients not having anything sticking out of their toes and not needing implants to be removed later, but in most instances, the costs of the implants outweighs these benefits.

I stopped using hammertoe implants several years ago, mainly because I like pinning toes across the metatarsophalangeal joints (MPJs), and because of implant costs and implant complications. I think digital K-wire fixation across the MPJ provides the best long-term toe alignment post-proximal phalanx joint arthrodesis.

An interesting cadaver study in Foot and Ankle International found that K-wire fixation is more stable than intramedullary hammertoe fixation devices.² The study compared 0.062-inch K-wire fixation to two Stryker implants, X Fuse and Smart Toe. The authors’ hypothesis was the implants would be stronger and stiffer than K-wires. The results? K-wire fixation won, by a lot. The K-wire average failure force was significantly greater than both implants and K-wires’ initial stiffness was greater than the Smart Toe.

Albright and colleagues conducted a cost-effectiveness analysis comparing K-wires to intramedullary hammertoe fixation devices.³ The authors determined percutaneous K-wire fixation for proximal interphalangeal joint arthrodesis for hammertoe “provides similar outcomes at substantially lower costs compared with commercially available intramedullary implants.” The authors cite a “marginal gain” for commercial implants in terms of efficacy but say the cost of implants does not justify their use. The study concludes that “From a healthcare system’s perspective, we have concluded that percutaneous K-wire fixation should be the preferred treatment for hammertoe correction. Commercially available intramedullary implants would be deemed more cost-effective than percutaneous K-wires if the device costs were reduced to ≤ $300.”

Kramer and colleagues, in their landmark 2015 study on almost 2,700 hammertoe surgeries with K-wire fixation, found what most surgeons who do hammertoe surgery see: some minor complications related to the K-wires.⁴ Surgeons left the pins in an average of 39.2 days (six weeks is your goal), 4.4 percent required early removal, 0.3 percent had pin tract infections, 0.1 percent had broken pins, 3.5 percent had pin migration, and 2.9 percent had pin extrusion. K-wire related complications were associated with a significant rate of revision surgery. The authors noted the average cost for an intramedullary hammertoe fixation device ranged from $500 to $1,000 and costs for a K-wire ranged from $10 to $40.

In my 28 years of practice and thousands of hammertoe surgeries, there are a couple of concepts I think are important with K-wire fixation for hammertoes. I only use 0.062-inch K-wires for all toes. I pin across the MPJ through the metatarsal base. Motion of the K-wire leads to irritation and irritation leads to infection. Eliminate motion, and irritation and therefore infection are significantly reduced. Pinning across the base with a 0.062-inch K-wire eliminates almost all motion. Leave the K-wires in for six weeks.

Sometimes the latest and greatest treatment is not really the latest and greatest. I will not be surprised if insurance companies no longer pay for intramedullary hammertoe fixation devices, resulting in facilities (hospitals and surgery centers) prohibiting their use. A couple of mixed-result studies on subtalar arthroereisis was all insurances companies needed to stop paying for that procedure. In today’s healthcare environment, resource utilization is incumbent upon everyone.

For hammertoe surgery, K-wires are stronger, stiffer and cheaper than implants, and provide excellent results with minimal complications.

References

1. DeHeer P. Keys to reducing the frustration of hammertoe surgery. Podiatry Today DPM Blog. Available at https://www.podiatrytoday.com/blogged/keys-reducing-frustration-hammertoe-surgery . Published March 11, 2014.

2. Rothermel SD, Aydogan U, Roush EP, Lewis GS. Proximal interphalangeal arthrodesis of lesser toes utilizing k-wires versus expanding implants: comparative biomechanical cadaveric study. Foot Ankle Int. 2018; 1071100718805066.

3. Albright RH, Waverly BJ, Klein E, et al. Percutaneous Kirschner wire versus commercial implant for hammertoe repair: a cost-effectiveness analysis. J Foot Ankle Surg. 2018; 57(2):332-338.

4. Kramer WC, Parman M, Marks RM. Hammertoe correction with K-wire fixation. Foot Ankle Int. 2015; 36(5):494-502.