Spinal decompression with patient-specific guides

Abstract

Background context: Patient-specific instruments (PSI) have been well established in spine surgery for pedicle screw placement. However, its utility in spinal decompression surgery is yet to be investigated.

Purpose: The purpose of this study was to investigate the feasibility and utility of PSI in spinal decompression surgery compared with conventional freehand (FH) technique for both expert and novice surgeons.

Study design: Human cadaver study.

Methods: Thirty-two midline decompressions were performed on 4 fresh-frozen human cadavers. An expert spine surgeon and an orthopedic resident (novice) each performed 8 FH and 8 PSI-guided decompressions. Surgical time for each decompression method was measured. Postoperative decompression area, cranial decompression extent in relation to the intervertebral disc, and lateral recess bony overhang were measured on postoperative CT-scans. In the PSI-group, the decompression area and osteotomy accuracy were evaluated.

Results: The surgical time was similar in both techniques, with 07:25 min (PSI) versus 06:53 min (FH) for the expert surgeon and 12:36 min (PSI) vs. 11:54 (FH) for the novice surgeon. The postoperative cranial decompression extent and the lateral recess bony overhang did not differ between both techniques and surgeons. Further, the postoperative decompression area was significantly larger with the PSI than with the FH for the novice surgeon (477 vs. 305 mm²; p=.01), but no significant difference was found between both techniques for the expert surgeon. The execution of the decompression differed from the preoperative plan in the decompression area by 5%, and the osteotomy planes had an accuracy of 1-3 mm.

Conclusion: PSI-guided decompression is feasible and accurate with similar procedure time to the standard FH technique in a cadaver model, which warrants further investigation in vivo. In comparison to the FH technique, a more extensive decompression was achieved with PSI in the novice surgeon's hands in this study.

Clinical significance: The PSI-guided spinal decompression technique may be a useful alternative to FH decompression in certain situations. A special potential of the PSI technique could lie in the technical aid for novice surgeons and in situations with unconventional anatomy or pathologies such as deformity or tumor. This study serves as a starting point toward PSI-guided spinal decompression, but further in vivo investigations are necessary.

Keywords: 3D printing; Decompression; Patient-specific; Spinal osteotomy; Spinal stenosis; Spine.