Tips and Tricks for Removing Problematic Implants: Intramedullary implants
- When removing intramedullary nails and all other types of intramedullary devices, it is absolutely essential to identify the type of implant.
- If the implant was inserted at a different hospital, a surgical procedure report should be available whenever possible.
- Hopefully, it will be standard practice to issue the patient with an implant certificate containing the most important data in the future. (However, to date this has proved to be a vain hope.)
- For modern nails (cannulated or solid) the appropriate set of extraction instruments must be available in order to drive out the locking screws and all the additional screws and to insert the set of instruments into the nails correctly.
- Universal nail removal kits are also available. These are characterized by threaded olives of various sizes which feature longitudinal slots. Difficult extraction procedures require that the greatest possible adhesion should be created between the set of instruments and the implant, in order that the extraction forces are transmitted without loss, resonance or elastic yield.
Tips and tricks for traditional Kntscher nails, ie, slotted tubular nails
- The correct taper must be selected.
- When screwing in, for each quarter-turn it is possible to tap at the rear with a hammer so that the taper, like a extractor screw, either fits perfectly into the thread or, in certain cases, even cuts a new thread.
- In the case of slotted tubular nails, the insertion force is limited by the expansion capacity of the nail. Even the traditional nail, with a swallowtail slot, cannot always prevent the proximal end from splitting apart.
- If tapping on the taper has no effect, the traditional extraction hook for Kntscher nails can be suspended in the slotted hole provided for this purpose (Fig 1). The extraction force is limited by the wall thickness. Frequently, if the nails are hard to extract, the solution is to cut into the wall.
- In principle, traditional slotted tubular nails should be released centrally beforehand, using a hand drill. In this way, frequent bone bridges, which have become ingrown in the slot, are removed.
- If it is not possible to extract proximally, extraction hooks can be used; these hooks should be long and thin enough to reach through the entire nail as far as the tip, where they can be positioned (Fig 2). For this procedure, the entire canal must be cleared beforehand, using a hand drill. The extraction hooks have small tips. It is necessary to verify, using the image intensifier, that the hook is suspended on the tip. Then the hook pushes the nail in front of it.
- If none of these steps were successful, the solution is distal fenestration. Using a curved plunger, the nail can be pushed from the distal to the proximal position. If conventional plungers are unsuitable, the surgeon can create a personalized plunger by bending a Steinmann nail or a Schanz screw.
- As a last resort, if removal is absolutely necessary, a lengthwise osteotomy of the bone can be performed. In this procedure, the lengthwise osteotomy proceeds in stages until the nail is released. It is preferable to carry out a targeted osteotomy rather than producing an uncontrolled comminutive fracture.
Removing broken nails
- An attempt should be made to push a broken nail from the distal to the proximal position (see above) and to keep the nail in one piece. This may prevent the distal fragment, with its sharp fracture edges, from hooking onto the internal surface of the medullary canal.
- If this fails to achieve the desired result, the first step is to remove the proximal fragment, followed by the distal fragment. In the case of slotted tubular nails, the tips and tricks described above can be applied.
- In the case of solid nails, the distal fragment can only be pushed. Individual plungers are recommended (see above). In some cases it may be possible to extract small distal fragments through a bone window.
- Broken cannulated nails can be removed using an extractor pin from the extraction kit or a home-made extractor pin. A typical example of a home-made extractor pin for femoral nails is a Schanz screw (Fig 3).
In every case, the objective must be to ensure that the Schanz screw (as long as possible) becomes embedded in the cannulation. A combination chuck or another suitable instrument must then be docked with the end of the long Schanz screw.
Removing broken locking screws
- The facing part does not pose any problem.
- The opposing part can be pierced. The projecting end of the screw shank can then be grasped from the opposite side.
- In certain cases the opposing half of the pin can be unscrewed using the internally threaded extractor pin.
DHS screws, PFN screws, blades, etc.
- Obtain the correct instruments.
- Read the operating manual.
- If other extraction options fail to achieve the desired result, remove using the extractor screws and the other tools for damaged and broken screws.
If these instructions are followed, removing problematic metal fasteners will prove to be an easily surmountable challenge.
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