Is local autogenous morselized bone harvested from decompression through a posterior-transforaminal approach sufficient for single-level interbody fusion in the lower lumbar spine?

Background: To determine the volume and applicability of local autogenous morselized bone (LAMB) harvested and used during posterior-transforaminal lumbar interbody fusion (P-TLIF) in the lower lumbar spine.

Methods: Clinical and radiographic data of 147 patients (87 males) undergoing P-TLIF from January 2017 to December 2019 for lumbar degenerative diseases were retrospectively analyzed. Computed tomography was used to assess the fusion status (at 6 months, 1 year, and the last follow-up postoperatively), restored disc height, graft fusion area and volume, and the minimum required bone volume (MRBV). Clinical outcomes of P-TLIF were assessed using the Oswestry Disability Index (ODI) and visual analog scale (VAS) for low back pain (LBP) and leg pain (LP).

Results: The mean follow-up period was 28.4 ± 4.49 months. The patient's age and diagnosis were correlated to the volume and weight of LAMB (mean volume and weight: 3.50 ± 0.45 mL and 3.88 ± 0.47 g, respectively). The ratio of actual fusion area to the total disc endplate and the ratio of actual fusion volume to the total volume of the disc space were > 40%. MRBV ranged from 1.83 ± 0.48 cm³ to 2.97 ± 0.68 cm³. The proportion of grade 4 or 5 fusions increased from 60.6% at 6 months to 96.6% at the last follow-up. The ODI, VAS-LP, and VAS-LBP scores significantly improved after surgery and remained unchanged during the follow-up.

Conclusion: When combined with a cage, the volume of LAMB harvested from decompression through the unilateral approach at a single-level is sufficient to achieve a solid interbody fusion in the lower lumbar spine with excellent clinical and radiographic outcomes.