Changes in foraminal area with anterior decompression versus keyhole foraminotomy in the cervical spine: a biomechanical investigation

OBJECTIVEAnterior cervical discectomy and fusion (ACDF) with or without partial uncovertebral joint resection (UVR) and posterior keyhole foraminotomy are established operative procedures to treat cervical disc degeneration and radiculopathy. Studies have demonstrated reliable results with each procedure, but none have compared the change in neuroforaminal area between indirect and direct decompression techniques. The purpose of this study was to determine which cervical decompression method most consistently increases neuroforaminal area and how that area is affected by neck position.METHODSEight human cervical functional spinal units (4 each of C5–6 and C6–7) underwent sequential decompression. Each level received the following surgical treatment: bilateral foraminotomy, ACDF, ACDF + partial UVR, and foraminotomy + ACDF. Multidirectional pure moment flexibility testing combined with 3D C-arm imaging was performed after each procedure to measure the minimum cross-sectional area of each foramen in 3 different neck positions: neutral, flexion, and extension.RESULTSNeuroforaminal area increased significantly with foraminotomy versus intact in all positions. These area measurements did not change in the ACDF group through flexion-extension. A significant decrease in area was observed for ACDF in extension (40 mm2) versus neutral (55 mm2). Foraminotomy + ACDF did not significantly increase area compared with foraminotomy in any position. The UVR procedure did not produce any changes in area through flexion-extension.CONCLUSIONSAll procedures increased neuroforaminal area. Foraminotomy and foraminotomy + ACDF produced the greatest increase in area and also maintained the area in extension more than anterior-only procedures. The UVR procedure did not significantly alter the area compared with ACDF alone. With a stable cervical spine, foraminotomy may be preferable to directly decompress the neuroforamen; however, ACDF continues to play an important role for indirect decompression and decompression of more centrally located herniated discs. These findings pertain to bony stenosis of the neuroforamen and may not apply to soft disc herniation. The key points of this study are as follows. Both ACDF and foraminotomy increase the foraminal space. Foraminotomy was most successful in maintaining these increases during neck motion. Partial UVR was not a significant improvement over ACDF alone. Foraminotomy may be more efficient at decompressing the neuroforamen. Results should be taken into consideration only with stable spines.

Changes in Foraminal Geometry With Anterior Decompression Versus Keyhole Foraminotomy in the Cervical Spine: A Biomechanical Investigation

Cervical spondylosis can be treated with various surgical decompression techniques, notably anterior cervical decompression and fusion (ACDF) and posterior keyhole foraminotomy1. Although each procedure has distinct methods, there is no compelling evidence in the literature to advocate one over the other. Furthermore, subtle differences within the techniques have yet to be examined such as the salvage or resection of uncovertebral joints during ACDF. Systematic reviews2,5 and meta-analyses3 have not elucidated significant differences in pain improvement between ACDF techniques, and no study has compared clinical outcomes for ACDF versus posterior foraminotomy, the two most popular cervical decompression techniques to date. We provide benchtop evidence as to the relative effectiveness of foraminotomy, ACDF with or without resection, and a combination of all surgeries. We hypothesized that ACDF with uncovertebral resection would be most effective to open the neuroforamina. Results of this study inform best practices for cervical decompression surgeries.