|Year : 2016 | Volume
| Issue : 3 | Page : 127-128
Atlantoaxial facetal distraction spacers: Indications and techniques
Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Parel, Mumbai, Maharashtra, India
|Date of Web Publication||16-Aug-2016|
Department of Neurosurgery, K.E.M. Hospital and Seth G.S. Medical College, Parel, Mumbai - 400 012, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Goel A. Atlantoaxial facetal distraction spacers: Indications and techniques. J Craniovert Jun Spine 2016;7:127-8
Treatment strategies for craniovertebral junction abnormalities have revolutionized following the understanding of the fact that atlantoaxial dislocation is seldom if ever fixed or irreducible.,,, The treatment that was focused on decompression of the neural structures has consequently changed to craniovertebral junction stabilization and realignment. The previously considered entity of “fixed” or “irreducible” atlantoaxial dislocation is more frequently encountered in cases with “degenerative” age-related atlantoaxial instability and basilar invagination and is sometimes secondary to trauma. The atlantoaxial dislocation in both these situations is mobile, and the joints are “pathologically” active. The dislocation in such situation can be both reduced and stabilized. The role of anterior transoral or posterior foramen magnum decompression has consequently become questionable, and these surgical procedures are rapidly but surely slipping into realm of history. The other important understanding is the fact that more than deformity or deformation of neural structures, it is the instability and its related repeated microtrauma or injuries to the cord that is the cause of symptoms. Consequently, the aim of treatment is focused on stabilization of the instability. Although reduction of the dislocation and realignment of bones is useful, the primary aim of surgery is to provide a more stable and lasting construct.
We introduced the concept of use of intra-articular spacers for distraction-reduction-stabilization of the atlantoaxial joint. We subsequently advocated the use of intra-articular interfacetal spacers for subaxial spinal stabilization.,, In the early part of our experience, we used spacers more frequently for the atlantoaxial facetal distraction in the treatment of basilar invagination and fixed or irreducible atlantoaxial dislocation. The articular cartilage of the joint was widely removed, and spacers were introduced along with bone graft chips harvested from the iliac crest. As we mature in our understanding of the region and on the basis of our increasing experience in the field, we have realized that opening of the joints and denuding of articular cartilage and subsequent introduction and packing of bone graft within the joint not only can provide distraction, realignment, and fixation and a material for bone fusion but also can avoid the need for placement and impaction of metal spacers within the joint. Opening of the atlantoaxial joint in cases with basilar invagination is a relatively complex surgical procedure. However, if it can be done and if bone graft can be introduced into the joint and direct facetal fixation using screws/rods is possible, the clinical and radiological outcome is most gratifying.
Opening of the joint and denuding of the articular cartilage and direct facetal manipulations using specialized instrumentation are maneuvers that by itself result in reduction of the basilar invagination and reduction of “fixed” atlantoaxial dislocation. More than spacers, it is the bone graft that is important and lasting and effective in providing stability and ground for arthrodesis. The techniques of facetal distraction have been gaining popularity over the years. A variety of modifications of the implants and variations in their usage have currently been described. However, it appears than more than introduction of the metal; it is the manual manipulations, ligament release, and bone graft impaction that is crucial in providing stability, reduction of dislocation, and a ground for bone fusion.
Intra-articular spacers in the atlantoaxial joint can provide strong fixation and stabilization of the joint and can be a standalone method of treatment. However, the exact indication of its use needs to be clarified. Spacers are required in situ ation when significant pressure is needed to distract the facets of Atlas More Details and axis and force is required to impact them in position. Bone graft impaction can also be a standalone method of stabilization and has the additional advantage of providing a template for bone fusion. Essentially, over the years, the use of metal spacers is used more as a stabilizer or fixator of the joint (rather than distractor) and is preferred only when other methods of stabilization are either not available, are not satisfactory, or need reinforcement. Such a situation is relatively rare.
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