As often happens in the Orthopaedic metalwork removal world we get a run of requests for the ID of older style implants.
This week we have had a couple of enquiries relating to the removal of metalwork and specifically the 'Coventry Hip Screw'
An older implant commonly used in children having undergone osteotomy for hip deformities - although there is evidence that the coventry hip screw has also been used for treatment of non union distal humeral fractures.
We were sent the following image from a a clinician at the Royal Orthopaedic Hospital, Birmingham. The implant is not usually gold, this was a retirement gift!
Its a great visual aid with annotated notes of what to you can expect to find with this implant.
The screws on the plate were usually slotted Sherman screws and not cross head like this.
The hexagonal locking nut A was placed on at the end of the fixation to secure the two parts using a spanner. (A narrow nosed mole grip is handy if appropriate spanner cannot be sourced).
The hexagonal nut B is built into the screw and again there was a piece of kit to insert the screw which was placed over a guide wire with predrilling to allow screw insertion. There may be some bone overgrowth around this which may need chiselling away to allow access again for a spanner or mole wrench.
C was the shank of the screw and as you can see has a smaller diameter than the screw itself D This can be surrounded by bone after some time, and as you can see the threads are not reverse cutting like a modern AO screw, therefore it can pose some removal problems when you are trying to back them out. Perseverance usually works.
As per all removal of metalwork, especially the older devices it is worth planning for the unexpected. Screws can be damaged over the years, or get damaged during the removal process.
We recommend using our "Ipswich Screw Removal System'' for removing these types of implants, it has a very comprehensive range of drivers, including legacy cross head and Sherman slotted along with a whole stack of useful instruments for tackling broken or damaged screws.
Removal of metalwork? We have you covered.....