Back Mechanic by Stuart McGill, (02) Back to Basics: Getting to Know Your Back and Causes of Pain, Notes

Post date: Feb 21, 2021 4:29:51 PM

Back Mechanic by Stuart McGill

(02) Back to Basics: Getting to Know Your Back and Causes of Pain

• • A critical component in back pain assessment is an explanation of basic injury and pain mechanisms that guide a solution. Learn how the spine functions, its role in relation to the rest of the body and what it means for individual pain causes. Think of the spine like a radio tower stabilized by guy wires. The foundation of the guy wires is similar to that of the network of muscles and ligaments that surround our spinal columns: they provide strength and support. These anchoring muscles also facilitate mobility. The muscles attached to the bones create mobility, not the bones.

  • The Neutral Spine. The spine travels from the base of the skull down to the pelvis. Natural or neutral position is the spine’s ‘home-base’ in which it is in its least stressed and most resilient position. Good posture maintains a healthy spine. A healthy spine in neutral includes the presence of three natural curves. Motion through the back is natural and promotes healthy tissue but the spine is at its strongest, most resilient and most supported position when in neutral.

• 1. Neck (cervical) - begins in the cavity in the back of the skull and ends where the neck meets the beginning of the torso. It curves gently inward towards the front of the body (lordosis.)

  2. Mid Back (thoracic) - begins at the point at the top of the shoulders and extends to the bottom of the rib cage. It curves outwardly away from the lungs (kyphosis).

  3. Low Back (lumbar spine) - begins at the base of the rib cage and extends through the base of the pelvis, or tailbone, curves inwards towards the abdominal organs (Lordosis)

• • Bones and Joints (Vertebrae and Discs) - The spinal column is comprised of individual bones called vertebra that are stacked one on top of the other. Each vertebra includes bony protrusions called processes that serve as anchoring points for important muscles and ligaments. The small bumps we feel running down the back are the processes. The actual discs sit several inches inward. Between the vertebrae are the discs, which are not bones but more like bone spaces. Each disc has tough outer rings of collagen (the same material that forms ligaments and tendons). Inside these hoops of collagen, each disc contains a gel-like substance called the nucleus. Within its collagen pocket, each nucleus is pressurized, which gives it the ability to bend. The actual joints of the spine are found behind the discs, on the side of the spine furthest away from the organs. These are called facet joints, of which there are two for every disc. The facet joints girdle the motion of each vertebrae as the spine bends, twists and turns., supporting shear forces. Like other joints in the body, they glide over one another to facilitate smooth movement patterns.

• • Two vertebrae with a disc between them form a motion unit, so that there are many that make up the full spine. The disc has a pressurized gel-like nucleus that carries the loads down the spine while allowing bending motion. There are two additional joints to each motion unit called the facet joints that guide spine movements. If overused, with too many repeated bends and twists, they become irritated and painful and eventually arthritic. If the disc becomes damaged, the facet joints will wear out faster.

  • If the spine is bent too far and too often, the discs will eventually crack or delaminate and eventually will break. Larger spines crack sooner as the bending stresses are higher.

  • Nerves - The spine houses the main spinal cord which runs from the brain down the spine with roots exiting at each spinal level. These sense pain, control movement and control function of various organs. Damage to the spine irritates or pinches the nerve roots causing back pain, as well as causing pain and numbness in distal parts of the body linked with that particular nerve. Disc bulges and arthritic bone are examples of things that can cause not only back pain but buttock, leg and foot pain.

• • Muscles - To best deal with pain, understand how muscles actually work. Focus on finding pain free movements with better motions, postures and loads.

    • The muscles play a protective role in preventing the delamination process that comes from repeated spine bending. They are arranged around the spine and are designed primarily to stop spinal motion. Torso muscles that are flaccid and weak, or out of balance with one another, allow back problems.

    • The rectus abdominis is anchored to the obliques, forming the abdominal wall. Together these act as a spring, enabling jumping, throwing, kicking and even walking. It allows the powerful hips to to transfer their forces through this spring-loaded core, sparing the spine while enhancing function. Training these muscles by taking them through a big range of motion is making a big painful mistake.

• • No muscle performs just a single function and this notion misguides rehabilitation. First and foremost the flexible spinal column must be stiffened to allow it to bear load. The muscles work together in various patterns to ensure this vital ‘sufficient stability.’ Only then can the muscles be coordinated to create motion and support loads. Muscles often span several joints, meaning that the action at one joint is constrained by its role at another. One cannot simply try to change one muscle without affecting the entire muscular ‘orchestra.’ All muscles must be in tune with each other, at the correct volume and at the correct tempo and time. These are easily identifiable features of perturbed function associated with pain that can be corrected with simple exercises that ‘re-educate’ pain free patterns. Strive to create movement competency in patterns that produce pain-free function.

  • Connective Tissues - Ligaments, joint capsules and fascia comprise the connective tissues. They function to limit end-range motion and, in the case of fascia, hold parts together. These tissues can become painful when they are strained with the joints at the end range of motion with repetitive motion and activity. The pain can be local as well as cause distal symptoms. This pain has a slow onset and lingers on. A stabbing onset is more characteristic of a disc bulge.

    • Fascia covers muscles and bundles of muscles. It can create a ‘swirly’ pain around the shoulders, low back and hip area. Fibromyalgia (when the fascia is highly sensitized) can result from trauma that rewires the brain’s sensitivity and triggering to pain. The best way to treat this is to discover pain free movements, then slowly and patiently expand them. Teach the brain pain free movement and overwrite the painful pathways.

  • Movement and Load - This is where the basic anatomy comes together and we understand how the back works as an entire unit.

    • What is load? When we pick up an object , or push on a heavy door, forces are applied to the body. There are direct loads on the body and there are interval loads. Joints experience force magnification based on mechanical disadvantage. Bending over to pick up an object requires the back muscles to contract with great force which is imposed on the spine joints. To bend forward with just bodyweight results in about one third of a ton of force. This is why it is so important to use joint sparing mechanics: keep objects being lifted close to the body, be aware of repeated and sustained postures that result in excessive spine loading.

• • Torso and back muscles vs limb muscles

    • Walking - Leg movement would not be possible without stiffness and stability to stop motion in the spine. This ‘fixes’ the pelvis to lift one leg and swing it forward while supporting the body’s weight on the other leg. The quadratus lumborum (a muscle on each side of the spine) assists in stiffening the torso and pelvis. It neither shortens or lengthens, rather it activates simply to stiffen and stop motion.

    • Opening a door - The hips and legs create a root into the ground as the arm reaches forward and pulls on the door handle. These upper and lower body forces work to twist the spine. The torso muscles stiffen against the twisting tendency to prevent this motion--a spine sparing movement strategy. Limb movement from limb muscles requires a stiffened torso. This principle is at the root of great athletic performance. Those who allow the spine to bend instead of taking advantage of the motion and power production of the hips will limit their performance and eventually hurt the back. Train the core to stop motion. Train the shoulders and hips to create motion. The spine and torso need to move in a coordinated ballet. Seek to optimize the linkage between the high motion joints and the arm and leg segments. The body needs to be kept in balance: weak links need to be addressed. To function in a pain-free fashion, all bodily component parts (including the spine) need to work together in a functional pain-free fashion.

  • Muscle Force and Stiffness - Spine muscle stiffness is the key to health, not flexibility. Sometimes the muscles are activated to add force and other times they are activated to create stiffness. All limb movement needs a stiffened core. The stiffness allows the spine to support loads. The bony posts on the vertebrae attach to the core muscles, which provide the essential stiffness so the spine does not crumble. To reduce pain, the torso rotation motion must originate from the hips and shoulders and not come through rotation and flexion of the spinal column. ‘Core’ muscles are all the muscles that attach the pelvis, spine and rib cage as well as those that cross the hips.

    • The muscles of the limbs (and hips) are designed to create motion.

    • The muscles of the core are (primarily ) designed to stop motion, therefore they follow a different set of rules.

  • Spine Stability vs. Mobility - Essential stiffness prevents buckling collapse of the spine when supporting a load, facilitates limb movement and acts as a corset around the spinal joints to stop micro movements that cause pain. A stiffened spine is a stable and functional one.

    • Stability comes from muscle stiffness. Injury causes laxity in the joints and pain. Insufficient stiffness allows micro movements that cause pain. It is critical to create a muscular ‘guy wire system’ or girdle all around the spine.

    • Stiffness and muscular effort need to be ‘tuned’ to the task--if we expend too much effort, we add crushing loads to the spine. With enough effort (and muscle tension) we ensure stiffness sufficient enough to prevent joint micro movement and the resulting pain. The right exercises done at the right time in the right way will train spinal control and stability. Achieving sufficient stability requires muscle activity for longer periods of time. The contraction levels are not substantial but are often sustained. Stability training begins with endurance training. Endurance needs to be acquired first, strength second. Too much strength too soon creates problems for back patients.

    • Mobility is necessary at the shoulders and hips,not the spine. The spine must be stiffened when performing tasks that impose spine load to best address back pain. Enhancing mobility in the spine causes needless suffering.

  • Understanding Injury Mechanisms - Pain sensitivity is a direct result of overloading the various anatomical parts with inappropriate movement. There is a definite cause and effect relationship. Recognizing and avoiding the various injury mechanisms is essential to living a pain free life. Some have a genetic component making them more susceptible to certain back conditions but all back pain can be managed. By understanding pain triggers, we understand the key to its abolishment and to avoid developing an injury to begin with.

  • Disc Bulges (aka disc herniation, sequestration, slipped disc) -- The injury occurs when a disc between two vertebrae develops a bulge which then presses on a nerve. There are two pain onset patterns: one is a slow onset associated with chronic spine flexion such as when sitting; while the other is a sharp ‘stabbing’ onset associated with a forward bend, such as picking up a pencil off the floor. An acute crisis usually lasts about two weeks for the inflammatory process to resolve. Learning to avoid the cause is key. Learning to hinge forward about the hips rather than bending the spine is sparing the spine. Through proper exercise, movement and posture, disc bulges can be made less painful, usually pain-free. The bulge will fit in one of three categories.

    • The first is a focused bulge around the periphery of the disc. This is caused by repeatedly bending the spine in the direction away from the bulge.

      1. A bulge in the posterior left side of the disc indicates the spine was repeatedly bent forward and to the right. This type is often found in those whose occupation involves repeated movements (loading and unloading a truck, digging with a shovel) as well as in athletes and sometimes in individuals with asymmetric hips. With this particular type of bulge, there are a number of tolerable bends possible before pain or injury strikes. This number is reduced when movement is performed with more load.

      2. The cat / camel exercise will not harm a bulge because it is unloaded but anytime the body bends forward to pick something up from a standing position, high spine compression is caused by the large extensor muscles that are activated. Movement pattern choices will either decrease or increase the bulge, worsening the pain. By choosing correct movement, the bulge is given the opportunity to shrink back down to size. Eliminate the risk of a disc bulge by moving about the hips rather than the spine.

• • End Plate Damage and the Flattened Disc - When the spine is compressed to the point of injury, the first place to experience damage is the bone of the vertebrae. Microfractures occur just under the growth plate, which then allows the end plate to crack. If the crack is large enough, the nucleus gel escapes into the vertebrae causing central ‘boring’ pain in the back. In this scenario it is best to avoid activities that place compression on the spine, such as lifting weights or bending forward. The flattened disc and compressed nerve roots can instigate a host of painful inflammatory responses.

• • Sciatica - refers to pain that originates down the spine but is felt along the sciatic nerve into the buttocks and down the back of the leg. The sciatic nerve runs down the back of the thigh, down the shins, to the toes, and can be traced back to the nerve roots that exit the spine at the L4/5 and L5/S1 levels. The pain felt in the legs or butt is a product of the sciatic nerve being pinched. In younger patients, the pain can usually be attributed to a disc bulge. In older patients, the pain likely derives from a bone spur. Eliminating sciatica depends on the cause of the nerve pinch. It can be influenced by posture and spine load but approaches differ.

• • Femoral Nerve Pain - is pain felt tracing down the front of the thighs often from a pinched femoral nerve. The particular nerve exits from the upper lumbar spine joints. Follow the same course of action as with sciatic nerve pain with minor tuning.

  • Radiating Sensations - are perceptions of pain that can be felt over the skin (dermatomes) and in certain muscles (myotomes). These can usually be traced back to nerve pinches in the lumbar spine. Foot numbness may be noted during or following certain activities. The key in alleviating the pain lies in avoiding those triggers. Not all sensations have connection with spine issues. A dull ache felt down the mid thigh, through the bone, is an indicator of hip joint pathology. Blood supply compromise (claudication) is another common cause of radiating symptoms. Be sure to check with the family doctor to rule out these possible health concerns.

  • Stenosis - is a ‘narrowing’ of the canals in the spine where nerves travel. The narrowing can be caused by protruding disc material, arthritic bone or hypertrophied ligaments. Stenosis often results in sciatic and radiating symptoms.

  • Muscle Pain - is rarely indicative of a muscle ‘sprain’ or a ‘tear.’ They do happen but are rarely the cause of pain. More likely, the issue can be sourced somewhere in the spine--the pain is simply ‘referred’ to the muscles. Stretching will stimulate the stretch reflex and may feel good at the time but long term, will create more damage to the spine underneath. Comprehensive testing will determine the true source of pain. Only then can the issue be properly addressed.

  • Facet Joint Pathology - Facet joints guide movement and thus, when sensitized, cause pain with certain movements. The pain usually has a slower onset and can take several weeks to desensitize. This is assisted by identifying the painful spine movements and avoiding them by moving about the hips instead.

  • Torn or Strained Ligaments - Ligaments can tear off the vertebral bones upon experiencing forced awkward joint postures such as a submission in martial arts. Ligaments can also be torn in their midsection from impact loads such as those experienced in vehicle collisions. These cause joint laxity and often result in long term joint pain. By avoiding spine bending altogether, through controlled movements and muscle stiffening, the joint can gristle and stabilize over time (may be over a year.)

  • Scoliosis - an unnatural side to side ‘s’ shape curvature in the spine. It can cause instability, disc bulges and pave the way for other injuries if not managed properly. Sometimes they are developed during growth years. Use Schroth exercises to assess and treat.

  • Muscle Inhibition - Often a byproduct of hip and back pain, certain muscle groups become inhibited, others become facilitated and feel tight. In general, back pained individuals develop inhibited glute muscles and psoas tightness (the large muscle that connects the spine and thigh.) The tightness is felt in the crease between the leg and torso. This muscular imbalance causes further changes to how load is experienced in the joints of the hip and spine. These are additional challenges, but patients facing these issues can still become pain free.

  • Traumatic Damage (Fractures and other traumatic tissue damage) - The first diagnosis and treatment of the damage should be done by trauma specialists. Sometimes the damage is more extensive than what is visible on medical images. Sometimes the cord is ‘shocked,’ causing disruption of the engrams. Other times, the perception of movement is mixed with pain perceptions so that syndromes such as fibromyalgia develop. Begin with simple pain free movements and slowly build the pain-free repertoire by overwriting the perturbed engrams.

  • A Word About the Aging Back - The nature of back pain is age-dependent. The discogenic pain, the pain that originates from a damaged vertebral disc, is rampant among the Young (30s-50s), yet rare among the more senior citizens. They are more likely dealing with arthritis and stenosis at that age if they experience back pain. Age should always be taken into consideration when matching a pain trigger to a therapeutic activity.

  • Understanding Pain: Why do we pick the scab? Flawed movement patterns continue to keep many of us pain sensitive. Much like a scab forming on skin, our backs are constantly trying to patch and heal themselves. We, however, by continuing to repeat harmful movement patterns in our daily lives cause re-injury, essentially picking the scab. It is unreasonable to expect the body to heal if we continue to provoke it in the same way that led to the original injury. Continued provocation of pain sensitizes the nerves so that pain is triggered with even less stimulation. The solution is found when we remove the provocative motion.

  • Pain Sensitivity - people increase their sensitivity to pain through repeated stressful and painful loading. The muscles and joints are loaded with sensors: pain sensors, pressure pressure sensors, force sensors, and chemical sensors. Some detect carbon dioxide, some pain, some detect histamine from inflammation. Human joints are packed with sensors that relay position and movement information to the brain. These signals travel along the sensory nerves. Along the highway of nerves are checkpoints (gates) and junctions.

  • Gate Theory of Pain - flood the checkpoint with ‘good information’ signals associated with pain free movement. In this way there is no more room for the pain signals as they are crowded out. Finding and repeating pain-free motions in the back will cause the remaining painful activities to hurt less. By discovering and ingraining positive movements for the back, pain dissipates then disappears entirely. By removing pain triggers, we ‘stop picking the scab’, giving the tissues a chance to rest, heal and regenerate. Simultaneously, the sensors for pain are being desensitized. Master this and we master back pain.

  • What is Psychosomatic Pain? - It’s all in your head. Certain individuals are prone to magnifying their pain. They get annoyed when their body is not functioning perfectly . One of their major fears is that their back trouble will cause them to lose their hard earned fitness. They want to know the exact date they can return to challenging training. Another type of patient is the one who is more focused specifically on the ache--they obsess over their pain. For those patients, finding something else to focus on can be a helpful tool. Don obsess. For both types, when pain is experienced throughout the day, acknowledge it and use it as a reminder to adjust postures and movement patterns. Focus on the solution rather than the problem and recovery will be more productive.

  • The Degenerative Cascade - Spine issues do not heal in a matter of weeks. The damaged and altered spine joint mechanics cause a cascade of issues that can last years. For example, an original injury in the spine endplate, may lead to a disc bulge, which will result in a flatter disc and narrowed joint space, which in turn may trap a nerve root. The flattened space places more load on the posterior facet joints that then respond by developing arthritis over the next few years. Thus motion becomes more painful as the new arthritic bone grown gnaws away at the nerve roots. Micro movement of the spine only continues to cause more irritation. This cascade can be managed. It may continue for a time internally, but the pain can be lessened and even eliminated with posture change and movement control. Managing back pain over time this way ensures it does not worsen, Eventually, if managed successfully, the joint will stiffen on its own over time (10 years) and the pain will subside and disappear.

  • Chapter Summary

    • To heal the back, recognize what is triggering the pain.

    • Understanding basic anatomy, posture and movement, as well as the specific injury will help to identify ways to avoid pain and discern between helpful and damaging courses of action.

    • Recovery strategy #1 - avoid the original pain inducing mechanism: the aggravating posture.

    • Various symptoms of back pain have a distinct and known cause. Injuries can be avoided if the injury mechanism itself is avoided.

    • Pain Avoidance Strategies

      1. Locate and eliminate the cause of pain -- get an appropriate assessment that provides a specific diagnosis.

      2. Increase awareness around movements and postures that cause pain.

      3. Develop replacement postures and movement patterns that enable you to function pain free.

      4. Stabilize the torso, core and spine to remove painful joint micromovements.

      5. Develop a daily exercise plan that involves walking

      6. Mobilize the hips.

      7. Learn to create power at the ball and socket joints (hips and shoulders)

      8. Learn exercises that are based on patterns of movement: push, pull, lift, carry, lunge, squat

      9. Make healthy spine choices when sleeping, sitting or engaging in more demanding activities.