A New Approach For Correcting Hammertoe Deformities
- Volume 16 - Issue 1 - January 2003
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Understanding The Real ‘Pearls’ Of The Technique
As far as pearls go in using the device, I feel one of the most crucial factors on whether the surgery is going to be successful or not happens prior to the first incision. The OR templates are a necessary tool for selecting the correct sizes of the components. You must take into account how much bone is going to be resected off both the middle and proximal phalanx. You must also confirm the threads of the two component system will engage some cortical bone internally. If not, you will get a “pistoning” effect of the implant in the soft medullary bone. This is very similar to what you could see with an internally buried threaded K-wire technique. This pistoning will not set things up well for an arthrodesis.
Obviously, you would want to resect as little off the base of the middle phalanx as possible as this bone is already short. You also do not want to disrupt an abundant amount of intrinsic tendon attachments.
You also don’t need to perform an aggressive resection of the head of the proximal phalanx. Resection of the head can be at, or just proximal to, the surgical neck of the bone. You only need to resect enough bone in order to distract the middle and proximal phalanx. This will give you clearance for the two component system to “snap” parallel into each other, as well as fully reduce the deformity at this joint level. Excessive shortening of the toes is discouraged.
When implanting the two components in bone, be aware that forceful manipulation is unnecessary. The soft medullary canal is very receptive to gentle drilling and implantation. I personally have not needed the power attachment bit and feel the risk is too high for a split bone cortex. I have found it very useful to slightly countersink the hex components on either side of the arthrodesis site. The male and female components will still engage and this does create some excellent bony apposition. It is highly recommended to insert the proximal (female) component first for obvious reasons. The “mid” or male portion is difficult to work around if you are still drilling and inserting the proximal portion at the joint.
When You Are Snapping The Device Together
The final step of snapping the device together is one of the most critical to the success of the procedure. I recommend using sterile gauze during this step to avoid slippage of your fingers on the toe. You should distract the middle phalanx gently in order to align the two components axially. If the two components are not in alignment, you not only risk a poor apposition, but damage to the implant itself.
You also need to be very persistent when applying significant pressure to get the device to engage. Strive for bone-to-bone contact. You will encounter several “alarming” ratcheting noises when compressing the components but this is normal. When the process is complete, you’ll hear a more “pronounced” snap but this just indicates that the components have completely seated themselves. Sometimes, you’ll need to slightly rotate the phalanges in order to obtain the full engagement of the “prox” and “mid” implant components. As your familiarity with the device increases, recognizing the final engagement of the implant becomes easier. You should confirm good bony apposition via visualization, probing and fluoroscopy.