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Whiplash: Part 1 - Biomechanical Breakdown

Updated: Mar 13


Woman Holding Her Neck After MVA

Whiplash injuries, or what we sometimes call Whiplash Associated Disorder (WAD), is a common type of condition often brought on by car accidents. Even though many whiplash cases get better relatively quickly, some WAD instances can evolve into chronic pain or disability. These more serious cases warrant careful examination and treatment.


When it comes to WADs, it's common for legal issues to crop up, making it all the more important to have a healthcare professional who truly understands these injuries. Such a professional will perform a detailed physical examination and provide the right treatment and exercise plan to ensure the best possible outcome.


So, what's on the agenda?


We're going to dive deep into this topic in a five-part series. In the first couple of parts, we'll get a handle on the nitty-gritty of how whiplash injuries occur by examining the three stages of a car accident and the body parts that often bear the brunt of the impact.

In the third part, we'll delve into the symptoms of whiplash injuries and what goes on during a physical examination, and we'll skim through the basics of how WAD is classified. When we get to the fourth part, we'll explore various non-invasive treatment options, even showing you examples of how both soft tissue and joint injuries are treated. Finally, to round off the series in part five, we'll highlight the significance of well-planned exercise programs. You'll get to watch video demonstrations of exercises usually recommended for patients.


Stay tuned; we'll make a complex issue easier to grasp! And remember, understanding is the first step toward resolution.

 

Understanding Whiplash Movements


Whiplash injuries can be more precisely defined as hyper-extension and hyper-flexion injuries, which paints a clearer picture of the actual biomechanics at play during the injury. It's key to understand that these injuries usually happen in a flash - within one-quarter of a second, to be exact. In rear-end collisions, car occupants don't have the time to respond or shield themselves from the impact.


We can compartmentalize the whiplash injury process into three distinct phases:

  • Phase 1: The Moment of Impact

  • Phase 2: The Neck's Over-Extension

  • Phase 3: The Neck's Flexion


MVA Image

Phase 1: The Moment of Impact


Let's explore what happens to a person's body when they are hit from behind in a car accident. At the point of initial impact, when the rear vehicle collides with the car in front, the force propels the front car forward.


Because the seat of the impacted car is fixed to the car's structure, it moves forward along with the car. However, the driver, not being physically attached to the car's frame, tends to stay in the same position due to a principle known as inertia. Inertia, as defined in physics, is the tendency of an object to resist a change in motion - in a car crash, this concept becomes vividly real!



Straight Spine

The car seat jolts into the driver's lower and middle back in a split second. This sudden forward push thrusts the lower part of the driver's neck forward. The result is a straightening of the natural curves in the driver's neck (known as the lordotic curve) and mid-back (the kyphotic curve). This generates an unusual S-shaped curve in the driver's neck, scientifically called the cervical spine.


This Impact Phase can inflict significant damage. With the neck forced into this abnormal S-shaped position, the small joints in the neck, known as facet joints, are pushed beyond their usual range of motion. This excessive movement leads to injury in the areas surrounding the facet joints. Damage may include tearing of the facet capsule ligaments, bone-on-bone contact, and internal bleeding within the joint (intra-articular hemorrhages). The extent of joint damage largely depends on the severity of the collision.

 

Over-Extension Image

Phase 2: The Neck's Over-Extension


In the second phase, the car's rapid forward movement jolts the driver's head backwards. The head can often whip back at high speed, going right over the headrest. This is particularly common when the headrest is set too low to provide effective support or if its design is subpar.


If the collision is particularly forceful, substantial damage to soft tissues and joints along the front of the neck can occur as the head is flung backwards.


Potential Damage in Phases 1 and 2 Various body parts, including muscles, nerves, facet joints, joint capsules, and ligaments, can sustain damage during a car accident's first and second phases.


Facet Joint Image

Injury to Facet Joints & Capsules

Facet joints, the most frequently injured joints in the neck, play a crucial role in supporting weight and regulating movement between each vertebra. They're also the most common culprits of chronic neck pain following a whiplash injury.


Given the intense muscle contractions and vertebral movements during whiplash incidents, the protective coverings of these facet joints, known as facet capsules, often suffer injuries too.



Spinal Ligaments Image

Injury to Ligaments

The Anterior Longitudinal Ligament (ALL), which traces down the front of the vertebrae, plays a crucial role in preventing excessive extension or the backward movement of the head. If this ligament is damaged, it can lead to instability in the neck (also known as the cervical spine). This instability could be a source of chronic neck pain that persists long after the initial whiplash injury.


Muscles & Nerves

Several muscles and nerves in the neck and shoulders are impacted during stages 1 & 2 of a hyperextension MVA. Here are some of the most common structures injured during the hyperextension phase of a whiplash injury.


Longus Colli Muscle Image

Longus Colli Muscle Damage

The Longus Colli muscle, a deep-seated muscle that extends from the topmost vertebra in your neck (C1) down to the mid-upper chest (T3), is frequently injured in whiplash incidents (7). This muscle is rich in neurological receptors called muscle spindles. These spindles act like detectors, monitoring changes in the muscle's length. Muscles abundant in spindle fibers typically play a role in fine motor control, muscle tone, and sense of position. Therefore, any injuries to these muscles can impact a wide range of motor functions.



Platysma Muscle Image

Injury to the Platysma Muscle

The Platysma is a surface muscle that lies over the sternocleidomastoid muscle (SCM). Originating from the connective tissue (known as fascia) in the upper regions of the neck and chest, it stretches out over the shoulder and down across the collarbone. Due to its widespread connections through the fascia, an injury to this muscle can influence multiple body areas.


The Platysma is controlled by the Facial Nerve (also known as Cranial Nerve VII). If the Platysma is injured during a car accident, the functioning of the facial nerve can be affected. This can lead to sensations like tingling across the face and upper chest, which are typical signs of facial nerve involvement.


Image of Scalene Muscles

Injury to the Scalene Muscles

The Scalenes are a trio of muscles on the side of the neck, known as the anterior, medial, and posterior scalenes. A cluster of nerves (the brachial plexus) and a significant artery (the subclavian artery) traverse through the anterior and medial scalene muscles. These areas often suffer injuries during whiplash incidents, potentially causing neurological or vascular issues that extend from the neck and shoulder down to the wrist and fingers. This type of damage is known as Thoracic Outlet Syndrome (TOS). Most TOS cases - about 90% - result from neurological, not vascular, damage.


Sternocleidomastoid Muscle Image

Injury to the Sternocleidomastoid Muscle

The Sternocleidomastoid (SCM) is a superficial muscle on the neck's side and front. The SCM plays a significant role in the flexion and rotation of the neck. Two important nerves - the Lesser Occipital Nerve and Greater Auricular Nerve - run past the SCM. Compression of these nerves, such as in a car accident, can result in a condition known as occipital neuralgia. This condition is characterized by chronic pain in the upper neck, the back of the head, and behind the eyes and is also referred to as C2 Neuralgia or Arnold’s Neuralgia.


The Spinal Accessory Nerve contributes to the motor control of the SCM and Trapezius muscles. Compressing this nerve during a car accident can lead to a limited range of motion and reduced strength in the SCM and Trapezius muscles, significantly impacting both shoulder and neck strength.


A Note: In our clinical practice, we frequently encounter headaches characterized by chronic pain in the upper neck, back of the head, and behind the eyes. These headaches can often be relieved through hands-on therapy and exercise.


Up Next: In the second part of "Understanding and Overcoming Whiplash Injuries," I will delve into the biomechanics of Phase 3 (over-flexion), and highlight the anatomical structures that are most likely to be injured.



 

DR. BRIAN ABELSON DC. - The Author


Photo of Dr. Brian Abelson

Dr. Abelson is committed to running an evidence-based practice (EBP) that incorporates the most up-to-date research evidence. He combines his clinical expertise with each patient's specific values and needs to deliver effective, patient-centred, personalized care.


As the Motion-Specific Release (MSR) Treatment Systems developer, Dr. Abelson operates a clinical practice in Calgary, Alberta, under Kinetic Health. He has authored ten publications and continues offering online courses and live programs to healthcare professionals seeking to expand their knowledge and skills in treating musculoskeletal conditions. By staying current with the latest research and offering innovative treatment options, Dr. Abelson is dedicated to helping his patients achieve optimal health and wellness.

 

Please Note: References for all five sections of this article can be found at the end of Part Five.


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