Execution
- 1Position the patient standing with the lumbar spine exposed.
- 2Inspect the low lumbar midline for a visible step or sill-like contour.
- 3Palpate along the lumbar spinous processes from cranial to caudal.
- 4Identify any abrupt anterior-posterior step between adjacent spinous processes.
- 5Document the suspected level and compare the finding with symptoms and imaging when available.
Positive outcome
A palpable or visible low-midline step-off or sill is positive. The sign suggests lumbar spondylolisthesis, although the palpable sill level may not exactly match the vertebral slip level. Magee’s observation section describes a step deformity as a possible sign of spondylolisthesis.
Studies
| Study | Reliability | Sn | Sp | LR+ | LR− |
|---|---|---|---|---|---|
| Ahn & Jhun (2015) | NA | 81.3 | 89.1 | 7.46 | 0.21 |
CommentThe low midline sill sign has promising single-study accuracy for lumbar spondylolisthesis, but it should still be interpreted against radiographs when classification or instability grading matters. It is more specific than a general palpation abnormality because it looks for a distinct step / sill. Body habitus and examiner palpation skill can affect detection.
Moderate Clinical Value