An in vivo dynamic radiographic imaging study of two sets of subjects (symptomatic and asymptomatic) revealed that some degenerative spondylolisthesis (DS) patients showed a greater range of aberrant motion, creating occult instability, in their mid-range kinematic images than previously exhibited on static imaging studies. The new data could have important clinical and diagnostic implications, as practitioners learn to distinguish between DS patients who might benefit from non-surgical interventions and those who require fusion to treat their condition.
Surgical spinal fusion and decompression with laminectomy are the remedies most often prescribed to patients suffering from lumbar DS, but some patients may be treated with decompression alone and avoid costly and potentially risky surgical procedures. Understanding how lumbar spinal instability contributes to DS can help predict which patients may be at risk of destabilization after laminectomy and thus require surgical fusion. The authors of this study sought to compare static and dynamic clinical radiographs to see if the full spectrum of rotational and translational kinematics were evident in MRI’s of subjects utilizing flexion/extension poses.
Seven Degenerative Spondylolisthesis patients and seven asymptomatic control subjects were imaged during torso flexion as a tracking system measured and calculated the movement of each vertebra and AP slip. Static, and dynamic radiograph images were obtained and compared. The results showed that the static radiographs did not detect the full spectrum of aberrant motion and underestimated AP slip. In contrast, the continuous dynamic imaging showed that DS patients demonstrated a wide range of aberrant motion with high kinematic heterogeneity that was not visible on the static radiographs.
The results of this ISSLS bioengineering prize-winning study suggest that the presence or absence of lumbar instability in DS patients should be considered and evaluated prior to prescribing treatment. Mid-range kinematics and AP translation may play an important role in determining the relative effectiveness of decompression and laminectomy with—or without—surgical fusion and might spare a subgroup of lumbar DS patients unnecessary expense, risk, and recovery from procedures that are potentially superfluous (or harmful) to their recovery.
KEYWORDS: Some DS Patients May Not Require Fusion Surgery to Improve, some degenerative spondylolisthesis (DS) patients showed a greater range of aberrant motion, creating occult instability, in their mid-range kinematic images, from non-surgical interventions and those who require fusion, static radiographs did not detect the full spectrum of aberrant motion and underestimated AP slip, kinematics and AP translation may play an important role in determining the relative effectiveness of decompression and laminectomy