SPSI Validity and Test-Retest Reliability Study

Orthopaedic surgeons are often faced with the clinical dilemma of whether or not to add fusion to a decompression procedure. To decide between these two surgical options, surgeons rely mostly on their experience to conclude if a level is unstable preoperatively or if a specific decompression procedure is likely to destabilize the spine. Recently, the Sagittal Plain Shear Index (SPSI) has been developed as a valid test for determining the degree of spinal (in)stability. The SPSI metric, which can be calculated using flexion-extension radiographs of the lumbar spine, informs the orthopaedic surgeon about whether the spine is stable in and of itself (necessitating decompression surgery only) or whether there is spinal instability (necessitating decompression and additional fusion surgery). The SPSI metric can be calculated using both the validated semi-automated QMA® and more recently developed fully automated Spine CAMP software platforms. The concurrent validity between these two software platforms, as well as the reliability of both of these objective diagnostic indicator for spinal instability have not yet been evaluated. This study will investigate if SPSI-metrics/values obtained with Spine CAMP are equivalent to measurements from QMA®, and will also investigate the repeatability of two measurements of the SPSI taken one hour apart ('test-retest reliability').

Inclusion Criteria:referral to the orthopaedic surgeon because of pain in the back or leg and requiring lumbar spine radiographs so the orthopaedic surgeon is able to diagnose the probable cause of the pain.over the age of 18 yearsability to flex and extend the spine sufficiently to facilitate acceptable flexion and extension radiographs.Exclusion Criteria:any form of spine-related traumatic injuryprior lumbar spinal surgerylateral spondylolisthesis or coronal plane curvature in the lumbar spine of >10°the presence of involuntary back muscle spasmsthe presence of significant changes in pain during the dayinability to understand and sign the study Informed Consent forminability to follow oral instructions