Transverse Pedicle Angle Is Associated With Pelvic Incidence and Increased in Lumbar Isthmic Spondylolisthesis

Abstract

Study Design: Retrospective radiographic review. Objectives: Investigate and quantify transverse pedicle angle (TPA), the medial-to-lateral pedicle angulation, and its potential association with pelvic incidence (PI) in patients with isthmic lumbar spondylolisthesis (ISLS) and compare to those with degenerative lumbar spondylolisthesis (DSLS) and controls. Methods: A total of 200 patients (64 ISLS, 70 DSLS, 66 control) were included. TPA was calculated at the L3-5 vertebral levels using axial computed tomography slices. PI was measured on lateral radiographs. Two independent observers completed the measurements. As a sensitivity analysis, TPA was also measured at the most cranial and caudal aspects of the L3-5 vertebral levels of a subset of participants (29 ISLS, 31 DSLS, 35 control) and the cranial to caudal change (ΔTPA) was calculated. Results: TPA values (mean ± SD) at L4 and L5 for ISLS (L4: 17.3° ± 3.7°, L5: 26.0° ± 5.2°) were significantly higher than those for the DSLS (L4: 14.3° ± 3.8°, L5: 22.2° ± 5.0°) and control (L4: 14.5° ± 3.9°, L5: 20.7° ± 3.8°) groups. TPA in the DSLS group was significantly higher than controls at L5, but not L4. High PI predicted wider TPA at L5 in both DSLS and ISLS. ΔTPA (mean ± SD) increased sequentially proceeding through the L3-5 spinal levels for the ISLS (L3: 6.8° ± 4.4°, L4: 8.7° ± 5.2°, L5: 15.6° ± 9.0°), DSLS (L3: 8.2° ± 6.0°, L4: 8.3° ± 5.9°, L5: 18.3° ± 7.2°), and control (L3: 6.8° ± 4.4°, L4: 8.2° ± 4.7°, L5: 17.7° ± 7.0°) groups. Conclusions: TPA was significantly increased in ISLS compared with DSLS and controls. High PI significantly predicted high TPA at the L5 vertebral level in ISLS and DSLS. ΔTPA increased sequentially proceeding through the lumbar spine across groups.

Comparison of L5 pedicle morphology in patients with and without L5 spondylolysis

“…The technique for measuring is significantly different however with digital calipers used in marked contrast to CT‐based measures and so a comparison of linear measurements is impossible. A significant majority of studies available that analyze pedicle morphology utilize advanced imaging modalities that offers some degree of clinical application (Coscia et al, 2020; Goyal et al, 2021; Hou et al, 1993; Matthews et al, 2015; Nojiri et al, 2005; Tang et al, 2021).…”

“…Pedicle screw insertion can be challenging in patients with abnormal anatomy and pedicle morphology has been suggested to vary in those with spondylolisthesis although studies are few and results have not been consistent (Choi et al, 2014; Coscia et al, 2020; Goyal et al, 2021; Matthews et al, 2015; Tang et al, 2021). In patients with isthmic spondylolisthesis at L5/S1 Tang et al have reported more abducted, shorter and wider L5 pedicles than in the normal population while Choi et al found more abducted, longer, wider, and taller L5 pedicles in those with spondylolytic spondylolisthesis (Choi et al, 2014; Tang et al, 2021).…”