Current And Emerging Insights On Hammertoe Correction
In recent years, there has been a move away from the percutaneous K-wire to other forms of fixation for digital correction in foot surgery. This has been spearheaded by the desire of the surgeon and patient alike to avoid the risks and pain of percutaneous fixation, and offer long-term internal stabilization of the corrected deformity. Today, there are at least five different implants commonly utilized by the foot and ankle surgeon. The implants that we will discuss include the Smart Toe (Stryker), StayFuse (Tornier) and Pro-Toe (Wright Medical Technologies). We’ll also discuss the use of absorbable pins such as Trim-It pins (Arthrex) and cannulated screws.
A Closer Look At Three Emerging Implants
The Smart Toe implant is a memory-based nitinol implant that compresses across the proximal interphalageal joint as it warms to the body’s temperature level. As a one-piece implant, there are no interconnecting parts, which allows for easy insertion.9 The newest generation comes in both a neutral and 10 degree plantarflexed implant, allowing for further correction of the digital deformity. The biggest drawback to this implant is the fact that it is a thermally reactive implant. As compression occurs, there is very little flexibility to change the position of the implant/digit if the surgeon does not approve of the initial correction.
The StayFuse implant is a two-piece interlocking titanium intramedullary implant the surgeon would use in the proximal interphalangeal joint. Both the proximal and distal aspect of the implant resemble a screw with threaded heads. The implant then snaps together giving the device its final construct. An advantage to this implant is that there is no violation of the distal interphalangeal joint and no exposed hardware, which decreases the risk of infection.10 We have noticed some complications in our practice if the device is not completely engaged at its interlocking mechanism, which has led to recurrence.
Pro-Toe is one of the newest implants released to the market. This implant has similar advantages and disadvantages to the Smart Toe and StayFuse. As a completely buried implant, the risk of digital infection is low. The proximal aspect of this device screws into the proximal phalanx. The surgeon broaches the middle phalanx and then impacts it onto the serrated distal flange, maintaining correction. This implant comes in both angulated (10 degrees) and non-angulated implants. The angle gives the surgeon the ability to position the digit in both a mechanically and cosmetically appropriate position during the procedure.
In our practice, we have had very successful outcomes utilizing this implant. The biggest advantage we have noticed so far is the absence of exposed hardware leading to decreased anxiety. We have also noted very little chronic swelling of the surgical digit.
How Effective Are Absorbable Pins?
Absorbable pins became a popular alternative to the traditional K-wire for the fixation of digital contractures. This is because this device’s functions are identical to the K-wire in its mechanical role. One can either cut and bury the absorbable pin within the proximal and middle phalanx, or drive the pin the entire length of the digit. Despite its mechanical strength, there is a flaw in the breaking point of this device. There was a common failure point of breakage as surgeons initially inserted the pin and drove it distally. Other possible flaws include production of sinus tracts with the potential for secondary bacterial infection within the digit.9