Transforaminal Lumbar Interbody Fusion (TLIF) aims to relieve nerve compression and fuse the affected segment in its anatomical position. Multiple approaches and interbody cages designs have been developed for this purpose. The study aimed to assess the early impact of posterior approach (open vs. minimally invasive) and interbody cage design on global and segmental lordosis, as well as disc height.

A prospective, multicenter comparative study was conducted with patients undergoing monosegmental TLIF at L4-L5 or L5-S1 using either open or minimally invasive procedures. Interbody cages utilized were either straight or banana-shaped, made from PEEK or porous titanium. Assessments included clinical evaluations (radicular and lumbar Visual Analog Scale) and radiological measurements (global lordosis, segmental lordosis, disc lordosis, and disc height) using segmental and centered profile X-rays preoperatively (PrO), immediate postoperatively (IPO), and at 3-months (3 M). The study focused on early effects of the approach and cage design on sagittal parameters.

From January to December 2021, 191 patients (129 in group A - open surgery, 62 in group B - minimally invasive) were included, exhibiting similar preoperative characteristics. Both groups showed significant improvements in clinical results and sagittal alignment at IPO and 3 M. Group A displayed notably higher segmental lordosis (3 M: 21°±7 vs 18°±8), while group B exhibited greater disc height. Mixed model showed that Banana-shaped cages were associated with greater increases in segmental lordosis, while straight cages provided superior disc height restoration.

Surgical approach has no influence on sagittal parameters. The design of the interbody cages has an influence on early segmental lordosis and disc height, with banana-shaped cages contributing more to the restoration of segmental lordosis.

IV