Sorry for the delay - busy week!
These are being performed along with a neurosurgeon and they are billing as co-surgeons on the main fusion procedure. They've agreed on using 22558 (and 22585 if extra levels done) and 22845 and 22851 for intrumentation and cage. So they've agreed on the anterior codes, but this procedure is really not anterior or posterior. The Encoder lay descriptions of the 22532-34 series just didn't seem to match what they are doing either, so I guess I'm really wondering if the most correct answer is unlisted???
Here are some pieces of a recent op note:
Procedure performed: Extreme lateral interbody fusion L3-4 and L4-5.
Pt was placed in the rt lateral decubitus position and the left flank was prepped & draped...A 1 in. incision was made over the L4-5 disk space with another 1 in. incision in between that and the spinous process. Palpation was used to provide entrance down through the psoas to the L4-5 disk space. Retractor was placed under spinal cord monitoring. Near total diskectomy - - - cages trialed and placed - - - same was done at the L3-4 level. Xrays obtained to confirm correct placement of hardware, wounds irrigated, wounds closed.
The neurosurgeon's note is more descriptive of the access and includes:
An incision was made in the left flank and then electrocautery was used for hemostasis. The subcutaneous tissue was divided down to the muscle wall. A 2nd incision was made at the lateral edge of the paraspinous musculature. Metzenbaum scissors were passed into the retroperitoneum and opened, not allowing the scissors to close in the retroperitoneum. They were then removed creating fascial defects in the paraspinous musculature, allowing penetration of the finger into the retroperitoneum. The retroperitoneal adhesions were broken up allowing organs to drop anteriorly away from the psoas muscles. Transverse spinous processes were identified. The L4-5 disk space was identified. A dilator with a neuro-monitoring was passed through the lateral incision into the retroperitoneal on the tip of an index finger passed through the paraspinous muscle incision. That fingertip was then used to guide the dilator down to the L4-5 disk space, slightly posterior in the disk space. - - - note goes on to describe the discectomy, etc.
Thanks in advance for everyone's help