Related Experiment Video
Updated: May 24, 2026
Multilevel Oblique Lumbar Interbody Fusion in Degenerative Lumbar Disc Disease with Instability
Published on: July 25, 2025
Would an anatomically shaped lumbar interbody cage provide better stability? An in vitro cadaveric biomechanical
Parmenion P Tsitsopoulos1, Hassan Serhan, Leonard I Voronov
1Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, IL, USA.
Study Design:
A biomechanical cadaveric study of lumbar spine segments.
Objective:
To compare the immediate stability provided by parallel-shaped and anatomically shaped carbon fiber interbody fusion I/F cages in posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) constructs with posterior pedicle screw instrumentation.
Summary Of Background Data:
Few biomechanical data are available on the anatomically shaped cages in PLIF and TLIF constructs.
Methods:
Twenty human lumbar segments were tested in flexion-extension (FE) (8 N m flexion, 6 N m extension), lateral bending (LB) (± 6 N m), and torsional loading (± 5 N m). Each segment was tested in the intact state and after insertion of interbody cages in one of 3 constructs: PLIF with 2 parallel-shaped or anatomically shaped cages and TLIF with 1 anatomically shaped cage. All cages received supplementary pedicle screw fixation. The range-of-motion (ROM) values after cage insertion and posterior fixation were compared with the intact specimen values using analysis of variance and multiple comparisons with Bonferroni correction.
Results:
All constructs significantly reduced segmental motion relative to intact (P < 0.001). The motion reductions in FE, LB, and axial rotation were 85 ± 15%, 83 ± 18%, and 67 ± 6.8% for the PLIF construct using parallel cages, 79 ± 5.5%, 87 ± 10%, and 66 ± 20% for PLIF using anatomically shaped cages, and 90 ± 6.8%, 87 ± 12%, and 77 ± 22% for TLIF with an anatomically shaped cage. In FE and LB, the reductions in the ROM caused between the 3 constructs were equivalent (P > 0.05). In axial rotation, the TLIF cage provided significantly greater limitation in the ROM compared with the parallel-shaped PLIF cage (P = 0.01).
Conclusions:
The parallel-shaped and anatomically shaped I/F cages provided similar stability in a PLIF construct. The greater stability of the TLIF construct was likely due to a more anterior placement of the TLIF cage and preservation of the contralateral facet joint.
