Morphometric Analysis for Surgical Treatment of Cervical Discopathy by Posterior Laminoforaminotomy: Radiologic Study and Technical Note.

BACKGROUND

The main concern with the posterior approach is the risk of postoperative segmental instability. The most commonly cited rule is that removal of the medial half of the articular facet provides adequate surgical exposure and has no effect on stability. The aim of this study was to define the areas of the articular processes in the cervical spine that can be safely removed.

METHODS

Computed tomography scans of 50 cervical spines were analyzed. Measurements were analyzed for bone removal assuming the standard technique of posterior laminoforaminotomy. The width of the facet was measured at the level of the widest dimension. The height of the articular process was taken from the bottom (in the case of inferior process) or top (in the case of superior process) of the process.

RESULTS

The mean width of the articular process ranged from 11.8 ± 1.5 mm (range, 8.3-15.7 mm) at the C2-C3 level to 14.6 ± 1.7 mm at the C6-C7 level. At the cervicothoracic junction (C7-T1 level), the mean width decreased to 14.0 ± 1.7 mm. The mean value for both sides when the inferior articular process was measured at all levels was 5.0 ± 1.4 mm (range, 4.5-5.8 mm). The mean height of the superior articular process was 7.7 ± 1.5 mm (range, 6.8-8.3 mm).

CONCLUSIONS

Based on our findings, our "5-5-7 mm rule" corresponds to the amount of bone removal for each step of the laminoforaminotomy.