Are Digital Implants More Cost-Effective Than K-Wires?

Allen Jacobs DPM FACFAS

It seems as though every major orthopedic distributor as well as a variety of orthopedic companies that you have never heard of are making digital implants in every shape and size. Typically, the advertisements for these implants are glued to the front of our publications or fall out as you open the journal. It seems as though there are more advertisements for digital implants than even for the laboratories competing for your pathology and nerve fiber density testing business.

Digital implants on average cost between $500 and $1,500. That is substantially more than you, as a surgeon, will receive for performing an arthrodesis of a lesser toe. Although you receive declining reimbursement for each digit that you correct at one sitting, the implant cost remains the same. In contrast, Kirschner wires run between $10 to $20 for the same procedure.

Of course, problems such as infection, malalignment, breakage and persistent swelling never occur with the use of digital implants. These problems are totally eliminated with such implants and are problems we only encounter when using Kirschner wires.

A Closer Look At The Literature On Digital Implants

It is interesting that those in our profession advocating the use of digital implants generally fail to cite literature suggesting that digital implants are in fact superior to K-wires.

A recent study published in Foot and Ankle International by Klammer and colleagues examined the rate of complications such as infection, loosening and wire breakage when utilizing Kirschner wires for the treatment of digital deformities.1 The randomized, prospective study involved hammertoe or clawtoe correction for 52 lesser toes via resectional arthroplasty of the proximal interphalangeal joint. The authors noted no statistically significant difference in complication rates at three weeks, six weeks or three months’ follow-up, suggesting that prolonged (six-week) placement of Kirschner wires did not result in any additional complications over those Kirschner wires remaining in place for only three weeks.

Ellington and colleagues looked at implant-assisted arthrodesis of digits utilizing the StayFuse implant systems.2 Union occurred in 60.5 percent of cases. The overall complication rate reported by these authors was 55.3 percent with complications including hardware failure, nonunion, rotational deformity, fracture and the need for revisional surgery. Yet the authors noted that the device was “efficacious” in the treatment of hammertoe deformity. Perhaps my memory is failing me at my advanced age. However, my own personal experience with Kirschner wires was never associated with a 55.3 percent complication rate.

Caterini and coworkers reported on the use of an intramedullary titanium screw for arthrodesis of the interphalangeal joints.3 The authors obtained fusion in 48 of 51 toes. They noted nonunion in three toes with a broken screw in one of these cases. The study authors added that they removed seven screws due to persistent pain at the tip of the toe. The authors concluded that the use of an intramedullary titanium screw was superior to the use of temporary K-wire fixation.

Scholl and colleagues (in a study accepted in 2013 for publication) reviewed the Smart Toe implant versus buried Kirschner wires for the treatment of digital deformities.4 The study focused on 117 digits over three years. The authors demonstrated no statistically significant difference between the use of the Smart Toe implant and buried Kirschner wires for the rate of malunion, fracture, nonunion or the need for revision surgery. Osseous union occurred in 68.9 percent of patients with Smart Toe implants in comparison to 82.1 percent of those with buried Kirschner wires. The study says 20.7 percent of Smart Toe implants were associated with fracture in comparison to only 7.1 percent of buried Kirschner wires.

In an earlier study published in the Journal of Foot and Ankle Surgery, Angirasa and colleagues did a retrospective analysis of 28 cases, comparing the outcome of the Smart Toe implant with Kirschner wire fixation.5 Assessing for achieved arthrodesis, pain, complications and return-to-work status at 7, 14, 21, 28 and 56 days post-op as well as six months post-op, the authors claimed superior performance of the Smart Toe and concluded that the use of this implant was “a reasonable choice” for hammertoe correction.

Witt and Hyer reported on their use of a one-piece intramedullary device (Pro-Toe) in a case series of seven toes on three patients.6 The authors noted no intraoperative complications or post-op complications approximately one year after the surgery. The authors concluded that the device “appears to be a viable alternative for the treatment of hammertoe.”

In Summary

Physicians are recommending digital implants as an alternative for Kirschner wire fixation in the treatment of hammertoes. In my experience and most of the reports available in the literature referable to Kirschner wire fixation of hammertoes, the incidence of infection, wire breakage, rotational deformity, nonunion and other complications is no higher and likely lower than those being suggested by advocates of implant assisted digital arthrodesis.

This is a world in which evidence-based medicine and cost containment will become increasingly significant. The question to be asked is not whether implant assisted digital arthrodesis is effective. The question really is whether implants are more effective than traditional Kirschner wire fixation and whether the potential increased effectiveness is in fact “cost-effective” so as to justify this significant increased expenditure for the correction of hammertoes with these devices.

In my opinion, the current literature does not support the cost-effectiveness of these devices. Furthermore, in my opinion, the complications associated with Kirschner wires have been greatly exaggerated by advocates of implant assisted digital arthrodesis.

References

1. Klammer G, Baumann G, Moor BK, et al. Early complications and recurrence rates after Kirschner wire transfixion in lesser toe surgery: a prospective randomized study. Foot Ankle Int. 2012 33(2):105-112.

2. Ellington JK, Anderson RB, Davis WH, et al. Radiographic analysis of proximal interphalangeal joint arthrodesis with an intramedullary fusion device for lesser toe deformities. Foot Ankle Int. 2010; 31(5):372-6.

3. Caterini R, Farsetti P, Tarantino U, et al. Arthrodesis of the toe joints with an intramedullary cannulated screw for correction of hammertoe deformity. Foot Ankle Int. 2004; 25(4):256-61.

4. Scholl A, McCarty J, Scholl D, Mar A. Smart Toe implant versus buried Kirschner wire for proximal interphalangeal joint arthrodesis: a comparative study. J Foot Ankle Surg. 2013 June 13. Epub ahead of print.

5. Angirasa AK, Barrett MJ, Silvester D. Smart Toe implant compared with Kirschner wire fixation for hammer digit corrective surgery: a review of 28 patients. J Foot Ankle Surg. 2012; 51(6):711-13.

6. Witt BL, Hyer CF. Treatment of hammertoe deformity using a one-piece intramedullary device: a case series. J Foot Ankle Surg. 2012; 51(4):450-6.

Comments

Excellent blog Allen (as usual)!

My biggest issue with the K-wire versus implant discussion is that I think every one of my patients I discuss this with would prefer not to have a pin sticking out of their toe for a couple or three weeks and get physically nauseous with the thought of my pulling it out. They would prefer something internal that they don't have to see.

I can honestly say that I find nothing wrong with K-wire fixation for this procedure but my patients would prefer to have an option.

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