Article Figures & Data
Figures
- Fig. 1
Preoperative CT scans of a 70 year old male: a) panel on the left shows axial CT cuts from L3 to L5, b-d) panel shows sagittal CT cuts through the entry (shaded orange), middle (shaded turquoise), and exit zone (shaded green) of the lumbar neuroforamina, e) axial CT cut through the L3-4 disc space showing the stenotic lesion in the middle zone at that level, f-g) sagittal CT cuts through the middle zone at L3-4, and the L4-5 level. The neuroforaminal height (orange shade area) is less than 5 mm. The neuroforaminal width is less than 2 mm. Both indicators are consistent with spinal stenosis.
- Fig. 2
Preoperative MRI scans of a 64 year old female: a) panel on the left shows axial MRI cuts from L3 to L5, b-d) panel shows sagittal MRI cuts through the entry (shaded orange), middle (shaded turquoise), and exit zone (shaded green) of the lumbar neuroforamina, e) axial MRI cut through the L3-4 disc space showing the stenotic lesion in the exit zone at that level, f-g) sagittal MRI cuts through the exit zone at L3-4, and the L4-5 level. The neuroforaminal height (orange shade area) is less than 3 mm and hence consistent with spinal stenosis. At L4-5, the neuroforaminal height is 5 mm (orange shade area).
- Fig. 3
Endoscopic view of the chisel used to perform a foraminoplasty. The cannula is docked at the lateral superior aspect of the facet joint. The chisel is introduced through the working channel of the endoscope starting in an upward direction and then chiseling in a downward direction by rotating the chisel 180 degrees to remove bone from the facet joint.
- Fig. 4
The chisel is advanced through the central working channel of the endoscope. A mallet may be used to advance the chisel for the foraminoplasty. Typically, a direct lateral approach to the foramen by dropping one's hand is more advantageous. The foraminoplasty can be facilitaed by chiseling in an upward diretion, then by rotating the chisel by 180 degrees followed by downward chiseling.
- Fig. 5
An endoscopic Kerrison rongeur can be used to finalize the foraminoplasty. It is most suitable for decompressing the most medial portion of the lateral recess by using a Kerrison with a 135 degree footplate. The Kerrison is directed past the leading edge of the facet joint, then rotated 180 degrees to remove bone by dropping one's hand.
- Fig. 6
A foraminal drill can be advanced directly to the inner working channel. The drill is attached to a power driver and can be used in forward and reverse. It is most suitable for expansile foraminoplasty around the inferior pedicle.
Tables
220 Study Patients Extruded Disc 24 Patients Contained Disc 82 Patients Disc Bulge 33 Patients Foraminal Stenosis 114 Patients 
The transforaminal gold 7 and 9 mm mm reamer is intended for the initial foraminoplasty to remove bony overhang from arthritic facet joints. It is cannulated and fits through the working cannula to minimize tissue trauma and to reduce pain during surgery. It has a mostly side cutting beveled tip which is less aggressive when advancing thus minimizing risk for dural injury. The outer diameter of the beveled tip ranges from 4 – 7 mm. It comes with a multidirectional T-handle. The 4 mm chisel is intended to perform a foraminoplasty using the outside-in technique. The instrument is semi sharp to obviate the need for sharpening. It has a handle with a metal cap for tapping with a surgical mallet. The 4 mm round drill is also intended for a foraminoplasty. It can be used on power for a more controlled removal of bony tissue. This drill bit is less likely to cause dural injury. It is used best for the final steps of the foraminoplasty. For example, it is very useful to drill of bone spurs of the superior articular process that compress the traversing nerve root. The 3.5 mm kerrison rongeur is designed to perform a foraminoplasty. This is done by hooking the instrument underneath the structure to be removed and cutting it by squeezing the handle. The 3-7 mm trephine cutters are intended to enlarge the foraminoplasty. It can be placed at the pedicle or facet joint. It is cannulated and fits over the 1mm and 1.65 mm steel or nitinol guide wire. The end of the trephine has serrations for improved grip and fine motor control. The handle attaches to the opposite end of the trephine and is cannulated as well to accommodate for the long guide wire.
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