Why Biomechanics Still Matter in the Treatment of LBP

This article is a treat for someone who wants to learn about the evolution and philosophy of Physical Therapy. As you desire to learn more about the management of your lower back pain, Dr. James Taylor summarized this podcast. He is a Doctor of Physical Therapy intern.

This article’s objective is to help people understand that there is no medical field that is perfect and knows precisely everything. What I am proud of my profession is the desire to bridge the gap of research and clinical relevance for the benefit of the consumer.

When management of back pain is not getting any better, self-reflection is vital to improve outcomes. There is no self-destruction or allowing the ego to impact the pureness in the act of helping people. Consumers are lost when seeking medical help when every profession brings a perception that they can help. We hope you find this article helpful as it is essential to understand the evolution of a professional trade.

Management of low back pain was very detailed and forgot the person as a part of the healing equation. That did not work as more people nowadays have lower back pain — the same time and era of modern science and stem cells. The profession and ourselves looked within are evolving. Like many evolutions, we tend to swing towards the extremes due to the logic of “if one does not work, then it must be only option B that works.” The answer lies in the gray middle, and the article and podcast explain why we need both perspectives in your care.

I hope you enjoy reading and listening to this content. This article is written to educate Physical Therapist and other rehabilitation professionals.

Dr. Ngo’s Personal History of Physical Therapy

In this episode, Dr. Ngo makes the argument that biomechanics holds an essential place within the context of the biopsychosocial model. Dr. Ngo graduated in 2004 from CSULB when the concept of the clinical prediction rule (CPR) was considered sexy and essential. This is the time when researchers such as Cleland were trying to standardize PT. This came for an excellent reason. Our profession wanted to ensure that ortho PT comes from the same playing field, and through the process, make it less daunting (by 5%) for students coming out of PT school. The trouble with CPRs is that a lot of people don’t fit within them. The osteopathic model influenced Dr. Ngo’s graduate school teachings. His professor came out from Michigan, which had a robust biomechanical emphasis on movement system impairments. An example was classifying spinal patients based on FRS (flexion-rotation syndrome) and ERS (extension-rotation) to target a specific region where the use of muscle energy techniques (METs) could be helpful. 

Adapting to Changing Times

By the time that Dr. Ngo sat for his OCS, the field was shifting from a pathoanatomical model to a more generalized model where you can’t isolate dysfunction or treatment to a specific segment. In light of this new information trend, Dr. Ngo attempted to swing both ways as it is important to understand both worlds to provide the best treatment for each patient. A lot of people gravitated towards explaining pain, and the pain science world helped to explain this. People use the pain science model too much to explain the inadequacy of why things they are the way they are….it’s not bad explaining this, however it is hard when you only have 40 minutes for an eval and/or are seeing 25 people and immersing yourself in that world through the biopsychosocial model. As PTs, our bread and butter are to address the mechanical system, something we do better than personal trainers or kinesiologists because that’s what we do. If we can’t explain, we have to keep asking why. Today, there is the discussion that we have to stop asking why specific dysfunction exists. However, we need to craft the art while laying on science for the foundation (80%) of our biomechanically-based treatment. 


What initiated the call for uniformity in PT’s approach to care? We can’t be too sure, but word came around that a writer, or editor, went to a PT clinic and experienced many different inconsistencies in the course of his treatment. His documentation of his experience put the PT world under pressure, so we developed the CPR rule to standardize PT and make it uniform. Coming in as a new grad, Dr. Ngo found the treatment of the spine to be very daunting and nerve-wracking. As he struggled with the inadequacy that he felt, Dr. Ngo went the Norwegian route with the work of Freddy Kaltenborn who utilized a lot of traction and decompression with subsequent localization of symptoms with fine movement and loading/unloading the joint followed by exercise, traction, and stabilization to facilitate the transfer from unloaded to loaded positions. After a few years in the field, Dr. Ngo wanted to do residency and fellowship, however, he couldn’t afford to take the pay cut, so he became obsessed with this material and attempted to teach himself by taking several courses through NAIOMT (North American Institute of Orthopedic Manual Therapy). Dr. Ngo chose NAIOMT because their curriculum required twice the number of didactics compared to other manual therapy programs. NAIOMT utilizes an evidence-based, eclectic amalgamation pulling from many different systems, though strongly baked on the Cyriax model. 

Applications of the NAIOMT model

 Part of the foundation of Dr. Ngo’s biomechanical argument comes from the Level 1-3 coursework of the North American Institute Orthopaedic Manual Therapy (NAIOMT). Erl Pettman, being a practitioner in the Canadian medical system with direct access, taught him to understand the importance of medical screening so they trained Dr. Ngo to have a mindset of safety. Along with this, they taught the difference between normal spinal mobility, hypermobility, hypomobility, and a novel concept of an unsound joint. Dr. Ngo focuses on not the pain associated with mobility but the applied function that comes as a consequence of hypomobility, hypermobility, or an unsound joint. Hypermobility usually involves one plane of motion.

An example is detectable excessive movement of a spinal segment unstable in the sagittal plane testing like Anterior shear with PAIVM or PPIVM testing, but the rotational plane is stable. An unsound joint involves multiple planes. You detect hypermobility, as pain could be associated, with 2 or more PAIVMs and PPIVMs movements of the spine. The interpretation is that the spinal segments cannot maintain movement integrity as it moves. This leads to excessive joint shearing and alters the axis of rotation.

Based on this assessment, you have an understanding of the natural course of what your patient’s spine has gone through. To understand the joint at this level allows the clinician to use this knowledge depth to make a treatment choice. An example is that if you find an unsound joint, you don’t manipulate through it. You protect it and alter your thrust technique vector to protect that zone. There is no business leverage through an unsound joint. You cannot use the passive restraint so you choose a manipulation vector that will restore motion, without going through the unsound joint segment.

This mechanical approach is clustered along with medical histories such as consideration of blunt trauma or overuse / repetitive trauma. For example, when someone says “my back pops”, the evidence says there is no mechanical damage. However, he believes and assumes the “popping” indicates joint instability until proven otherwise.

The next distinction to make within this system is the difference between the noisy victim (pain and impairment) and the silent culprit (no pain but impairment that is driving the root cause of the symptoms). A common sign of the noisy victim is hypomobility…which usually indicates an underlying unsound joint which trips up scenarios because, with an unsound joint, the body will adapt through osteophytes, ligamentous hypertrophy. If a joint were truly unsound, initially, the person may feel good, however later they are more in pain. In the typical subjective report for these patients, the cardinal report is intermittent, recurring low back pain that transitions from low back pain periodically to no pain after 40 years old. This represents the transition from unsound to hypermobility (utilizing the passive system for core stabilization).

If you only have 15-20 minutes with the patient, it would be easier to fall back on just saying they have to cope with the pain, we have to also realize the impact that exercise and manual therapy can have on treating the dysfunction and avoiding the patient from simply coping with the pain. 

Application of Biomechanics to LBP Treatment 

Two points that drive Dr. Ngo’s practice is the sentiment that the question you ask determines the decision you make, and the decision you make leads to your destiny. This is because Dr. Ngo wanted to be the safest and was on a mission to avoid flaring up any of his patients. The other point he would ask himself would be “how can I be aggressive at the same time while being safe?” Dr. Ngo came from a camp in his schooling / early years where clinicians tended to underload people, so from exercise science, he chased after this question. One of the answers to this he found in the joint-by-joint-alternating-system theory by Gray Cook.

A key example from this system within the context of LBP is that the lumbar spine craves stability because it tends to be hypermobile. So by design, the lumbar spine is designed to facilitate sagittal plane motion and reduce rotation (only 30 degrees rotation), while the purpose of the facet is to distribute the WB (typically this ranges around 10-25% but as you get arthritic changes, it increases to 50-60%).

Returning to Dr. Ngo’s previous points about degenerative changes in MRI, you also have to look at facet orientation, as this can aid or limit more rotation. Because the lumbar spine tends to crave more stability, lumbar facets tend to be oriented sagittally. Anatomically, there aren’t many restraints moving into rotation however, so the flow of force goes to the annulus and the oblique. Remember, the annulus’s role is to restrict motion, and the orientation is like a rope with a 45 deg lattice to limit rotation. If you get disruption in this, you get disruption of the nucleus. With further sustained trauma, you get degeneration in the endplate.

This is really what initiates the cascade because it is where hydration/nutrition exchanges take place (fat infiltration, nerve ending growth takes place). If we’re not paying attention to progression, we want to go too fast and then this shearing happens which flares people up. This doesn’t pain science, it’s exercise science. In the course of Dr. Ngo’s development as a clinician, he had the duel of being the safest and then being aggressive utilizing the joint-by-joint model to determine how he could treat…who does he have to nurture with movement science ( joint by joint, Sahrmann, breathing tactics) and who he needs to be more aggressive with. 

Final Recommendations

A strong recommendation of Dr. Ngo’s is the 1st edition of the OCS Current Concepts. The material in this edition had very dry material but also key info and insight into how the spine works so you can apply anatomy and physiology. Other recommendations include looking into the movement and exercise science worlds to provide your in-depth knowledge on how to prevent rotational stress and shearing to minimize flare-ups, such as the work and teachings of Stuart McGill. Ultimately, you have to understand the patient’s whole history, look at the MRI, and test different movement systems…very rarely does it become pain science, it’s more functional medicine. If you have questions, ask them, because discussion promotes learning.  

Please comment and let us know what your thoughts on this subject.

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Danh Ngo PT, DPT, OCS, SCS

Doctor of Physical Therapy

Board Certified Specialist in Orthopedic and Sports Medicine

Onbase University Certified Pitching Specialist

Certified Advanced Movement Specialist – RockTape

Certified Mobility Specialist – Rocktape

Mind Body Health Results Coach