A Rat Tail Cyclic Compression Model for Studying Intervertebral Disc Mechanobiology

Background Intervertebral disc (IVD) responses vary with loading magnitude, frequency, and duration. Existing loading systems are often mechanically complex and costly, while device input alone may not represent disc deformation. We developed a five‐channel motor‐driven system to relate graded cyclic displacement to mechanical and tissue responses. Methods Twenty 11‐week‐old male Sprague–Dawley rats were assigned to sham, low (0.4 mm), moderate (0.8 mm), and high (1.2 mm) compression groups ( n = 5 per group). Eight additional rats underwent characterization of peak compressive force, disc height deformation, wedge angulation, and sagittal plane anterior–posterior (A–P) translation. Outcomes included imaging, histology, cartilaginous endplate morphometry, and immunohistochemistry. Results Displacements of 0.4, 0.8, and 1.2 mm generated peak compressive forces of 3.94 ± 0.46, 8.69 ± 1.15, and 14.54 ± 1.31 N and radiographic disc height deformations of 13.00% ± 4.05%, 31.11% ± 8.38%, and 58.08% ± 10.27%, respectively. Wedge angle and sagittal plane A–P centroid offset did not differ significantly across the four displacement states ( p > 0.05). After 4 weeks of cyclic loading, the low compression group resembled the sham group. Moderate compression preserved disc structure and increased matrix marker positive areas. High compression caused disc narrowing, T2 signal loss, nucleus pulposus disruption, increased MMP‐13 positive area, reduced cartilaginous endplate dimensions, and more frequent and severe endplate abnormalities. Conclusions Prescribed displacement produced graded mechanical and tissue responses, with axial disc height reduction as the predominant group level radiographic deformation. This simple, low‐cost system provides an amplitude tunable platform for intervertebral disc mechanobiology research.