Repair and stabilization of the thoracolumbar region of the spine for coronal plane and sagittal plane reduction and intervertebral spacer insertion utilizes various tools and implants. These tools provide access to the thoracolumbar region, insertion of spacers, insertion of pedicle screws and other anchors and attachment of rods to these screws and anchors. Improved tools for anchor insertion, rod reduction, reduction screw tab removal and spacer insertion are desired.
For example, various techniques are currently being used to fuse lumbar spine vertebrae to treat specific types of spine disorders and to alleviate pain. These include the minimally invasive procedure lateral lumbar interbody fusion (LLIF) that accesses the intervertebral disc space and fuses the lumbar spine using a side (lateral) surgical approach rather than a front (anterior) or back (posterior) approach. As a minimally invasive approach, LLIF reaches the spine through several small incisions, reducing tissue trauma, scarring, post-operative discomfort and pain medication use.
The LLIF approach facilitates a 90° vertical reach parallel to the disc and the posterior wall of the vertebrae. Specifically in patients with coronal deformity, discs are often approached from the concave side, which permits easier access and reduces the number of incisions. However, access to L4-L5 makes an exception due to the position of the iliac crest. In patients with a coronally oblique L4-L5 disc and a high crest, a convex side approach is used. If the mid lumbar concave approach and the side of the L4-L5 approach do not correspond, a contralateral L4-L5 approach is used. After posterior fixation, table break cannot be used to open the space between the ribs and the iliac crest. Therefore, L4-L5 cannot be reached without angled measurements.
In addition to the limited number of disc levels that can be accessed, patient specific anatomy can provide for only a left or right approach. Before surgery, the width of the working window to each space is checked by looking at the position of the vessels and lobar plexus in axial MRI/CT slices. Depending on the axial anatomy, one side could be considered safer for access than the over side.
Angled inserters that are connected to intervertebral spaces having a centered attachment point allow for the instrument to be used for both a left approach and a right approach. However, if the attachment point of the intervertebral spacer is off center, then two separate inserter instruments are required based on the direction of approach. These separate inserters have a fixed alignment and spacer attachment based on the direction of approach. Therefore, a single angled inserter instrument is desired that can be used for both left and right approaches during an LLIF procedure.