Cervical Disc Disease: Biomechanical Aspects

Abstract

Degenerative disc disease in the cervical spine may cause significant pain and disability. Patients present themselves with neck pain, radiculopathy, and/or myelopathy. When the symptoms do not improve with conservative treatment, surgical treatment is considered. The goal of surgical treatment is to decompress nervous structures and to restore the normal anatomical conditions of disc height, alignment, and stability.

The present thesis concerns four studies involving the treatment of cervical disc disease. A new protocol Distortion-compensated Roentgen analysis (DCRA) for measuring the biomechanical and motion capabilities of the cervical spine were applied.

The first study compared DCRA with radiostereometric analysis (RSA) for measuring sagittal plane segmental motion in the cervical spine. Averaged over the cohort investigated, the measurements of sagittal plane segmental motion were not significantly different between DCRA and RSA. The second study was a descriptive study demonstrating that DCRA-measured disc heights from radiographs were significantly associated with MRI-defined progressive disc degeneration. However, within each category of degeneration, the measured disc heights were widely scattered. The inter-observer agreement between two neuroradiologists was moderate in defining both degeneration and disc height by MRI.

The third study demonstrated, in a prospective setting, the kinematic changes that occurred at segments adjacent to a one-level cervical arthrodesis. We did not find a significant change between the preoperative and the 12-month postoperative states of rotational and translational motion at adjacent cranial and caudal levels. Thus, the results did not support the assumption of an iatrogenically-caused increase in mobility at adjacent levels.

The last study showed several unfavourable outcomes when analysising radiographic parameters after an anterior cervical discectomy and fusion (ACDF) with a “stand alone” cylindrical titanium cage. At 12 months after surgery, solid fusion was achieved, but with significant cage subsidence and vertebral malalignment.