On the nature of facetal distraction spacers.

Dear Sir,

We have all been following the birth and evolution of your philosophy of atlantoaxial intraarticular or facet spacers right from the beginning and seen it spread worldwide.[1] During this evolution not only its efficacy has been proven but the indication of the technique also extended to a point that transoral surgery will probably someday really become a memory of the past for every surgeon dealing with this pathology.

On reading your recent editorial “Atlantoaxial facetal distraction spacers: Indications and techniques”[2] we wanted to make a contribution to the discussion from our point of view as to the nature of the spacers inserted into the atlantoaxial articular cavity.

The distraction or “joint jamming” technique is in itself already a procedure that represents its very own technical peculiarities especially for the novice or “ first time user.” In 2013, we reported on our first case of facetal distraction in basilar invagination with a variation of the technique that we felt helped to make the approach easier for us.[3] We essentially distracted the exposed joints with a laminar spreader and introduced semi-cured bone cement into the cavities. Once cured the cement thus provided an excellent maintenance of distraction and the operation was completed with instrumentation and application of an autologous tricortical iliac crest graft between the occiput and C2 for fusion. In a subsequent case, we used an appropriately cut cylindrical titanium mesh cage filled with bone but noted at follow-up that this had subsided on one side even though not leading to any clinical problem. In yet another case, we used autologous iliac crest bone chips inserted into the joint cavities but unfortunately noted at postoperative control that the distraction was not as efficient as we had planned for. We had thus reverted to the initial bone cement technique for a following case with the same positive result.

We feel that the solution of bone cement is not only easy to perform but also efficient, with virtually no risk of subsidence and last but not least comes at a very low price which is a factor not indifferent in many parts of the world, becoming increasingly relevant also in “our neck of the woods.”

Finally, we felt that in our case with metal spacers, besides the subsidence, the distortion on follow-up magnetic resonance imaging (MRI) was a problem. Some authors recently published their experience with the insertion of commonly available subaxial anterior cervical fusion polyetheretherketone cages and this could probably be an ideal compromise where substantial distraction is required as the polymer has a low potential of subsidence, can be filled with bone graft, does not produce artifacts on MRI and comes generally at a reasonable price.[4]

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Conflicts of interest

There are no conflicts of interest.