For those reading this who may not recognize the terminology used by the Postural Restoration Institute (PRI), the acronym–“LAIC RBC”–stands for, “Left Anterior Interior Chain, Right Brachial Chain.” This is a postural pattern the PRI has identified in a standing position. From my perspective, this pattern is just one of many possible patterns that might result from what I call the RALF Pattern (Right Anterior, Left Fixed).

A quick overview of the RALF Pattern: This pelvic pattern is extremely common and widespread and starts with the asymmetrical shortening of the primary hip flexors. Namely, the iliacus on one side and the psoas on the other side both becoming functionally short. (And the root cause of this phenomenon is long hours in a sitting position, a by-product of the progression from the Industrial Revolution to the Technological age.)

This is the anchor of pelvic torsion–the counter-rotation of the two pelvic bones–and results in a functional leg length discrepancy. When a person is standing, a functional leg length discrepancy will cause the body to be knocked off its centerline of gravity. This results in a cascade of muscular compensation as the body naturally seeks homeostasis and tries to bring itself upright.

By far, the most common manifestation of this I have observed is the shortening of the right iliacus and left psoas which results in a pattern I have named, Right Anterior, Left Fixed, or RALF, for short. Here the right innominate is anteriorly rotated by the short right iliacus, while the left innominate is prevented from a rotating anteriorly by a short left psoas. This accounts for the left hip region routinely becoming immobile or “fixed”, especially in the anterior aspect and often causing a reduction in mobility of the left hip capsule. 

But the primary dysfunction–the RALF Pattern and a functional leg length discrepancy–stacks up differently from person to person. Some respond with an S Curve in the spine; others with a C Curve. There are also numerous additional factors which impact the body’s “upright” response: trauma/injury, surgeries/scar tissue, unconscious postural habit patterns (like unconscious clenching of the abdominals, gluteals and pelvic floor muscles). All of these add up to a complex array of adapations in each person. While there can be similarities from person to person, each individual will express unique patterning.

While the end result of the RALF Pattern may look like what PRI calls the “LAIC RBC Pattern”, they are not synonymous. In my view, the RALF Pattern is foundational. On the other hand, a designation like the “LAIC RBC Pattern,” is a secondary observed pattern among many possible patterns that could result from pelvic torsion and a functional leg length discrepancy.  Because of these factors, my focus is on correcting the underlying foundational pattern.

  • Hello, I’m wondering how Left AIC pattern can be a result of RALF pattern. Left AIC seems to say that the left side of the pelvis is tipped forward, while RALF seems to say the right side is tipped forward.

    • This is definitely a confusing topic, so hopefully, I can shed some light. The Left AIC Pattern is caused by a functional shortness of the right leg due to the anterior rotation of the right pelvis. This anterior rotation functionally shortens the right leg. In a standing position, this short right leg causes the left hip to jut or “tip” forward. However, this forward jutting is different from pelvic rotation. The left side of the pelvis jutting forward is a functional compensation resulting from the leg length discrepancy, not a direct indication of the torsion pattern. Since these compensations from pelvic torsion and leg length discrepancy are at play in a standing position, an accurate assessment of pelvic torsion requires evaluating the patient in a supine position.

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