Parameters for lateral extent of dissection during anterior cervical decompression and fusion.

The purpose of this anatomic study was to determine the extent of lateral dissection that can be performed during anterior cervical decompression and fusion to maximize decompression without compromising the vertebral arteries. Although vertebral artery injury is rare, it is sometimes catastrophic and leads to significant morbidity and mortality. Previous studies have attempted to establish standards for surgical anatomy during anterior cervical decompression and fusion; however, none have accounted for significant degenerative changes that occur with increased age.The uncus-to-uncus distance, representing part of the vertebral endplate, of 500 cervical spine specimens was measured at each vertebral level from C3 to C7. The corresponding femoral head diameter (a correlate of body mass index) was also measured. These values were used to determine whether a specific uncus-to-uncus distance exists per vertebral level regardless of age, and whether the uncus-to-uncus distance becomes more specific when correlated with body mass index. According to the data, uncus-to-uncus distance increases between each vertebral level, and each level has a range of approximately 6 mm. The range does not decrease when compared with femoral head diameter. Although a statistically significant, positive correlation existed between uncus-to-uncus distance and femoral head diameter, the correlation coefficient was not large enough to suggest that uncus-to-uncus distance varies greatly from femoral head diameter. Although anatomical markers such as the distance between the uncinate processes can aid surgeons in safe decompression of the cervical vertebrae, vertebral artery injury is best avoided by thorough pre- and intraoperative radiological and anatomical analysis.