The Effect of Implant Placement on Sacroiliac Joint Range of Motion: Posterior vs Trans-articular.

Soriano-Baron H, et al. Spine. 2015 Feb 19. [Epub ahead of print]

STRUCTURED ABSTRACT: 

Study Design. A human cadaveric biomechanical study of two sacroiliac joint fusion implant placement techniques.

Objective. To evaluate and compare the biomechanical properties of two implant placement techniques for sacroiliac joint fusion.

Summary of Background Data. Minimally invasive placement of sacroiliac joint fusion implants is a potential treatment for sacroiliac joint disruptions and degenerative sacroiliitis. Biomechanical studies of screw fixation within the sacrum have shown that placement and trajectory are important in the overall stability of the implant. Although clinical results have been promising, there is the possibility that a more optimal arrangement of implants may exist.Methods. Bilateral sacroiliac joints in seven cadaveric lumbopelvic (L4-pelvis) specimens were tested using a single leg stance model. All joints were tested intact, pubic symphysis sectioned, and treated (three sacroiliac joint fusion implants). The implants were laterally placed using either a posterior or a trans-articular placement technique. The posterior technique places the implants inline in the inlet view, parallel in the outlet view, and parallel to the posterior sacral body in the lateral view. The trans-articular technique places all implants across the articular portion of the sacroiliac joint. For all conditions tested, the range of motion was tested in flexion-extension, lateral bending, and axial rotation.

Results. The posterior technique significantly reduced the range of motion in flexion-extension, lateral bending, and axial rotation by 27% ± 24% (p = .024), 28% ± 26% (p = .028), and 32% ± 21% (p = .008), respectively. The trans-articular technique significantly reduced the range of motion in flexion-extension, lateral bending, and axial rotation by 41% ± 31% (p = .013), 36% ± 38% (p = .049), and 36% ± 28% (p = .015), respectively. No significant differences were detected between the posterior and trans-articular placement techniques (p>.25).

Conclusions. Posterior and trans-articular placement of sacroiliac joint fusion implants stabilized the sacroiliac joint in flexion-extension, lateral bending, and axial rotation.