A simple test to determine “active” spondylolisthesis

Many patients have spondylolisthesis and it’s a concern as to when and how to best decompress them.  Slippage on flexion/extension films can certainly indicate the “stability” of the segments but can be impractical and mercurial. By simply elevating the prone patients’ legs bilaterally from the ankles (creating a shear at L5) pain provocation becomes obvious. Upwards of 10% of the population may have this anomaly but most aren’t necessarily in pain from it directly, and degeneration typically stabilizes the motion segments at that level in a large percent. This simple procedure (from McGill) can help us recognize if a patient presents with: 1. a shear-instability or 2. an active spondylolisthesis generating the shear-instability. When uncovered positioning should minimize the shear (extension) and thus supine or prone with slight flexion or an abdominal roll are most appropriate. Since our exam already involves checking for extension/recumbent extension tolerance or intolerance the awareness of these issues should already be apparent and this additional check a pertinent verification. Proper use of the McGill shear-instability test (palpation of the lumbar spine half-lying on the table) along with these other procedures should capture most patients’ conditions and lead us to the best possible outcomes.