What to do: Patient lies supine. Lift one leg straight up. Positive sign: The patient feels pain in the SI joint or sacrum. When the clinician provides external compression to the iliac crests (squeezing the pelvis), the pain reduces. Interpretation: The pain reduces because external compression mimics the force closure that the Andersson Link should provide. If manual compression helps, the link is weak.
In the world of orthopedic physical therapy and sports rehabilitation, few concepts have sparked as much debate and practical application as the Andersson Link. For practitioners specializing in the lumbar spine, sacroiliac (SI) joint, and lower quadrant dysfunctions, understanding this biomechanical phenomenon is not just an academic exercise—it is a clinical necessity. andersson link
Whether you are a seasoned physical therapist, a chiropractor, a strength coach, or a patient trying to decipher your diagnosis, this long-form guide will break down everything you need to know about the Andersson Link. We will explore its origins, its biomechanical function, how it differs from adjacent concepts (like the "force closure" of the SI joint), and why it remains a somewhat controversial but highly useful model in manual therapy. What to do: Patient lies supine
Because the Andersson Link influences the curvature of the lumbar spine, a hypertonic (overly tight) link reduces the lumbar lordosis. A flattened lumbar spine increases intradiscal pressure on the posterior annulus fibrosus, potentially accelerating disc bulges or herniations (especially at L4-L5 or L5-S1). When the clinician provides external compression to the