Single-Level Cervical Fusion: Where Does the Motion Go?
Despite advances in less invasive procedures to treat cervical spine conditions, approximately 175,000 cervical surgeries, including fusion, are performed annually. It is widely accepted that spinal fusion does not result in a complete cure and that there are risks for development of future dysfunctions.
Schwab, et al, compared the motion effects of single-level spinal fusion at different levels of the cervical spine. The results, published in Spine in 20061 confirmed that there is significant increased motion at spinal segments adjacent to fusion.
The authors studied seven cadaverous spines (C2-T1) to determine the effects of spinal fusion at different levels. Then spines were tested in flexion, extension, right and left lateral bending, and right and left axial rotation. The study found the following:
Motion compensation was distributed among the unfused segments with the most significant compensation at levels adjacent to the fusion.
Significant compensation occurred at the level above C3-C4 and C4-C5 fusions in flexion and extension.
Significant compensation occurred at the levels above and below C5-C6, C6-C7 fusions, with the most significant amount of increased motion below those segments.
The authors note that the motion compensation pattern seen on flexion and extension was not present in many of the spinal levels on lateral bending and rotation. The authors hypothesize that this may be explained by the coupling effects of the facet joints , which may transfer the motion to the remaining segments, resulting in a better load sharing response.
Relying on prior studies2345, the authors note:
- Apparent accelerated degeneration of adjacent disc segments occurs in an alarming number of cases over time.
- Common pathologic conditions at adjacent segments include disc degeneration, disc herniation, instability, spinal stenosis, spondylosis and facet joint arthritis.
- The authors conclude that their findings support the notion that single-level fusion contributes to adjacent level disease.
In the medical-legal context, it is important for healthcare practitioners and attorneys to understand and effectively communicate with one another concerning the long-term effects of procedures such as fusion. When traumatic injury has long-term implications for a person’s health and quality of life, knowledge of likely future impairment and health care needs allows all the parties to plan and secure fair and reasonable compensation for anticipated healthcare needs. When the healthcare professional and attorney work together, the interests of the patient-client are best served.
1 Schwab MS, DiAngelo DJ, Foley KT. Spine 2006; 31: 2439-2448
2 Perbino P, Bernazzo F, Borroneo U, et al., Degenerative Arthritis of the Adjacent Spinal Joints Following Anterior Cervical Fusion: 3 Clinioradiologic and statistical correlations. Ital J Orthop Traumatol 1990;16:533-4
4 Cummins BH, Robertson BT, Gill SS. Surgical experience with an implanted artificial cervical joint. J Neurosurg 1998; 88: 943-8
5 DePalma AF, Rothman LH, Lewinnek GE, et al. Anterior interbody fusion for severe cervical disc degeneration. Surg Gynecol Obstet 1972; 134: 775-8.
6 Hunter LY, Bronstein EM, Bailey RW. Radiographic changes following anterior cervical fusion. Spine 1980; 5: 399-401