For over a century, the world of manual therapy relied on a structural-mechanistic paradigm. Patients were told their "vertebra is out of place" and that a rapid manipulation—the famous "click"—would "put it back." While seductive in its simplicity, this concept does not withstand the scrutiny of modern science.

 

Today, through the lens of advanced biomechanics and pain science, we understand that the click is not a structural correction of a displaced bone. In this article, we clarify what truly happens inside the joint, why manipulation works, and why without balancing the soft tissues (STB method), manipulation may only serve as a temporary "band-aid."

 

Chapter 1: The Physics of Sound – From Cavitation to Tribonucleation

What is that noise? The classic answer was Cavitation—the collapse of gas bubbles in synovial fluid. However, a 2015 breakthrough study by Prof. Greg Kawchuk using real-time MRI revealed a different phenomenon: Tribonucleation. The sound is actually generated at the moment a vacuum (void) is created by the rapid separation of joint surfaces that were temporarily "stuck" due to surface tension.

Clinical Insight: The click is physical evidence that we have reached the end-range of the joint and achieved separation. It is an acoustic byproduct, not the definitive measure of therapeutic success.

 

Chapter 2: The Neurological Revolution – The Brain as Control Center

If we didn't "move a bone," why is there immediate relief? The answer is Neuro-modulation. A High-Velocity Low-Amplitude (HVLA) thrust triggers a massive stimulus to the proprioceptive system. Mechanoreceptors within the joint capsule (Ruffini endings, Pacini corpuscles, and Muscle Spindles) send a flood of sensory data to the spinal cord.

According to the Gate Control Theory, this rapid sensory input "outruns" slower pain signals (C-fibers) and blocks them. Furthermore, manipulation activates the Periaqueductal Gray (PAG) in the midbrain—the center for endogenous pain modulation—leading to an immediate release of natural opioids and cannabinoids.

 

Chapter 3: The Importance of Soft Tissue – The STB Model

Giveon Peled, developer of the STB (Soft Tissue Balance) method, argues: "The joint is a slave to the muscle." A joint doesn't become "stuck" in a vacuum; it is restricted by imbalanced muscle tone (Hypertonicity). When the nervous system perceives a threat, it creates a protective spasm.

If we perform an HVLA thrust on a joint held by rigid, inflamed tissue without treating the tissue itself:

1. The result will be temporary: Within hours, the muscle tension will pull the joint back into its restricted state.
2. Tissue Trauma: Rapid thrusting on a severely shortened muscle may trigger a reverse stretch reflex, increasing pain. STB "calms the guards" (the muscles) first, allowing the manipulation to be performed with minimum force and maximum effectiveness.

 

Chapter 4: Biomechanics and the "Disc Herniation" Myth

A properly executed manipulation actually improves fluid dynamics within the disc and reduces intradiscal pressure by restoring segmental mobility. The "click" in the Facet Joints often releases trapped "meniscoids" (small synovial folds), allowing for an immediate return of range of motion and improved blood flow to clear inflammatory markers.

 

Chapter 5: The Psychological Aspect – The Patient as a Partner

The click has a profound psychological impact. For some, it is a sign of "release" (positive placebo); for others, it causes anxiety (nocebo). At Manual IL, we emphasize:

• Pre-explanation: It's gas, not bones breaking.
• Empowerment: We aren't "fixing" the patient; we are helping their body regulate itself. When the threat level in the nervous system drops, chronic pain decreases.

 

Chapter 6: Safety First (The Golden Rule)

Not everyone is a candidate for manipulation. We maintain strict Screening protocols:

• Red Flags: Ligamentous instability, severe osteoporosis, or advanced neurological signs (e.g., Cauda Equina) are absolute contraindications.
• Vascular Assessment: Before cervical manipulation, an evaluation of the vertebral arteries is mandatory to rule out vascular insufficiency.

 

Summary: The Manual IL Integrative Model

Does the click realign a vertebra? No. The bone wasn't "out," and the click didn't "put it back." What occurred was a complex process of physical pressure changes, neurological flooding, and reflexive muscle relaxation.

 

The Manual IL approach combines the technical HVLA precision of Eyal Feigin with the tissue-attentive philosophy of Giveon Peled. To achieve sustainable change, we must treat both the "joint" and the "motor" that drives it.

 

Want to master HVLA techniques and learn how to integrate them with high-level soft tissue balancing? Join our flagship course: Manual Therapy integrated with STB at Manual IL.