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Posterior instrumentation surgery for craniocervical junction instabilities: an update.

The surgical treatment of craniocervical junction (CCJ) instability has recently undergone significant development and change. Posterior instrumentation surgery has been the mainstay of treatment of CCJ instability, and is the focus of this review. For the treatment of atlantoaxial instability, C1-2 transarticular screw fixation has shown good stability, and has been regarded as the "gold standard" procedure. Because of potentially hazardous complications including vertebral artery injury, however, C-1 lateral mass-C-2 pedicle screw fixation is gaining popularity. For treatment of atlantooccipital instability, occipitocervical fixation using screw constructs (combined with either rods or plates) has shown more stability than sublaminar wiring techniques, and has been utilized more frequently. Both innovation in material engineering and in vitro biomechanical studies have contributed significantly to the development of more rigid internal fixation devices, and as a result, many patients who would have been treated conservatively with external orthosis are treated nowadays with instrumentation surgery, resulting in earlier ambulation, shortened hospital stay, and earlier recovery into social activities. New surgical techniques and instruments, however, need to stand the test of time to see whether they are free from long-term adverse events. The rapid turnover of new surgical techniques and hardware has made it difficult for less experienced surgeons to keep up with the latest developments. Conventional techniques can be safer and less technically demanding than newer techniques for those who are not familiar with them.