Osteopathic Manipulative Treatment: Muscle Energy Procedure - Cervical Vertebrae

Anatomy and Physiology

Understanding muscle physiology is essential for MET. There are 4 types of muscle contraction: isometric, concentric, eccentric, and isolytic. Isometric contraction is when the muscles contract without having the origin and insertion of the muscle approach each other. Concentric contraction is when the muscles shorten with contraction. Eccentric contraction is when the muscle lengthens with contraction. Finally, isolytic contraction is when an external force lengthens muscle contraction.[6]

A muscle is made up of many muscle spindles. Each spindle comprises 3 to 12 intrafusal muscle fibers surrounded by a large extrafusal fiber. Each spindle has an efferent and an afferent neural component. Motor nerve fibers innervate the extrafusal fibers through the alpha motor neurons, and the gamma motor neurons innervate the intrafusal fibers. The Ia and II fibers innervate the muscle spindles' afferent (sensory) portions. The Golgi tendon organs (GTOs) in the myotendinous junctions are innervated by the Ib fibers.[7]

The GTO is crucial in the MET post-isometric relaxation mechanism and is simulated when muscle tension is elevated. This tension activates a negative feedback loop to prevent contraction via the Ia fibers.[8] 

This article will explain the physiology involved in post-isometric relaxation, the most commonly used form of MET. Dr. Mitchell Sr. hypothesized that after an isometric contraction, the muscle is in a refractory state where it may be passively stretched without a reflexive contraction. In MET with post-isometric relaxation, the GTO is activated by putting increased tension on the muscle fibers by asking the patient to contract against a barrier. Once activated, there is a reflexive inhibition and relaxation of the muscle through the Ia fibers, and the physician may further passively stretch the muscle due to the refractory state.[8]

The cervical spine comprises seven vertebrae, anatomically unique from the other vertebral segments. This region's key structural features are the cervical bifid spinous processes, transverse foramina, and triangular vertebral foramen.[9] The upper cervical spine (C1 and C2) consists of the atlas (C1) and the axis (C2). The atlas, a ring-shaped vertebra lacking a body, articulates with the axis by encircling the dens below and the occiput above. The dens of C2 is a remnant of the body of the atlas (C1) that ultimately fuses with the body of C2.[10] The facets of cervical spines are typically oriented backward, upward, and medially.

In contrast to C1 and C2, the 5 vertebrae in the lower portion of the cervical spine (C3 to C7) have a vertebral body and an uncinate process, a feature unique to the cervical spine that consists of a hook-shaped process on the superolateral margin designed to limit movement of the intervertebral discs during rotation. The uncinate process forms an uncovertebral joint (joint of Lushka) as it articulates with the uncinate process of the subsequent segments.[11] Furthermore, several ligaments connect each spine level, including the anterior and posterior longitudinal ligaments, the ligamentum flavum, and the interspinous ligament. The nuchal and transverse ligaments articulate at the cervical spine level only.[9] The alar ligament originates from the dens of C2 and inserts at the foramen magnum. The transverse ligament starts from the atlas and attaches to the lateral mass of C1 to hold the C2 together, forming the cruciform ligament.[12]

Nerve roots exit between the cervical vertebrae. There are 8 cervical nerve roots, 7 of which exit above the corresponding vertebrae. For example, the C6 nerve root will exit between C5 and C6. The last cervical nerve root will exit between C7 and T1. Cervical nerve roots will form the brachial plexus from C5 to T1.[13]

The structure of the cervical spine allows for a wide range of motion in all 3 planes (sagittal, transverse, and coronal). Forward flexion and extension of the neck occur in the sagittal plane. Side bending, or flexion to the right or left, occurs in the coronal plane. Rotation to the left or right occurs in the transverse plane.[14] The primary motion of the occipitoatlantal (skull and C1) joint is flexion and extension, the atlantoaxial (AA) joint (C1 and C2) is rotation, C2 to C4 is rotation, and C5 to C7 is side-bending. Most of the flexion and extension of the cervical spine will occur at the occipitoatlantal joint (OA).

Due to the shape of the semi-lunar articulation between the occiput and the atlas, side bending and rotation occur in different directions during flexion and extension. An example of somatic dysfunction at the OA would be flexed, rotated right, and side bent left (F Rr Sl). The atlantoaxial joint is primarily in rotation. To localize motion at the AA joint, the physician should flex the patient's neck to at least 45° to lock out motion in the lower cervical spine so that rotation may occur only at the AA joint. The remaining cervical spine exhibits rotation and side bending in the same direction during flexion and extension.

Indications

Indications for using muscle energy to address a cervical somatic dysfunction require a diagnosis with objective physical findings and ensuring that the patient is a candidate for osteopathic manipulative treatment.[15]

Contraindications

Contraindications to muscle energy techniques are divided into absolute and relative contraindications. Absolute contraindications include trauma, bone fractures, joint dislocation, infection, lack of patient consent, or muscle tears. Relative contraindications include cervical spine instability, internal bleeding, and recent myocardial infarctions or surgery.[16] Rheumatological conditions are also considered a relative contraindication and depend on disease severity and anatomical location of the joints affected.[17]

Upper cervical instability has been recorded in many studies of rheumatoid arthritis.[18][19] When a patient with rheumatoid arthritis presents to the clinic with neck pain, imaging to assess for cervical spine instability should be completed first. Down syndrome may also present with upper cervical instability.

Equipment

Muscle energy technique (MET) is a hands-on osteopathic manipulative treatment that requires a stable, firm surface and cushioned table for optimal treatment positioning and patient and physician comfort.

Personnel

Required personnel include a competent physician trained in muscle energy techniques.

Preparation

Appropriate diagnosis is crucial before starting treatment for somatic dysfunctions.

Diagnosis of OA Dysfunction

1. The patient is supine, and the physician is at the head of the table facing the patient. The patient's head is cupped, so the fingers are under the OA joint. 

2. The physician can then induce flexion or extension at the OA and then gently side bend in either direction. Somatic dysfunctions are named towards freedom; it is essential to determine the position of freedom. When the side bending direction of freedom is determined, the physician can deduce the direction of the dysfunctional rotation as it is the opposite direction.

Another method to determine the diagnosis is to find the side of the rotation first. While cupping the occiput, the physician can then palpate for the side of the "deeper" OA. The direction with the deeper OA is the direction of rotation; therefore, the side bending will be in the opposite direction.

3. Flexion and extension should be induced before diagnosis.

Diagnosis of AA Dysfunction

1. The patient is supine, and the physician is at the head of the table facing the patient. The neck is then flexed 45° to lock out the lower cervical segments.

2. Motion is tested by rotating the head in both directions.

3. The lesion is named based on which direction is freer in rotation.

Diagnosis of C2 to C7 Dysfunction

1. The patient is supine, and the physician is at the head of the table facing the patient. The lateral edges of the articular pillars are palpated.

2. Side bending of the segments is induced by translating in the opposite direction (right translation will cause left side bending)

3. Flexion and extension are checked in each segment to determine the diagnosis.

Technique or Treatment

The technique is explained to the patient as a mutual collaboration between the operator and the patient, which is necessary. Several muscle energy techniques address dysfunction at the OA joint, AA joint, and within the remaining cervical vertebrae. 

Occipitoatlantal Dysfunction Muscle Energy

1. Dysfunction of the OA joint should be diagnosed first (ie, OA flexed, rotated left, side bent right (F Rl Sr)). 
2. Using one hand to hold the patient's head, the other is placed at the OA junction to monitor the joint's articulation.
3. The patient's head is placed towards the barrier or in opposition to the diagnosis (ie, if the patient is OA F Rl Sr, the patient should be rotated to the right, side bent to the left, and extended). 
4. The patient should be instructed to attempt to move their head back into a neutral position and provide an isometric force for 3 to 5 seconds.
5. The patient should be repositioned further toward the barrier, and step 4 should be repeated. 
6. Repeat steps 4 and 5, 3 to 5 times, and reevaluate the dysfunction.[20]

Atlantoaxial Dysfunction Muscle Energy

1. Dysfunction of the AA joint should be diagnosed first (ie, AA rotated left (Rl)). 
2. The neck should be flexed to lock out the joints below the level of the AA joint while holding the patient's head with both hands. 
3. The patient's head should be rotated toward the barrier (ie, if AA Rl, turn the patient to the right).
4. The patient is then instructed to attempt to move their head back into a neutral position and provide an isometric force for 3 to 5 seconds. 
5. The patient is further repositioned toward the barrier, and step 4 is repeated. 
6. Steps 4 and 5 are repeated 3 to 5 times, and the dysfunction is reevaluated.[3]

C2-C7 Dysfunction Muscle Energy

1. First, dysfunction of a vertebra should be diagnosed (e.g., C4 flexed, rotated right, side bent right (C4 F Rr Sr)). 
2. While holding the patient's head with one hand, the articular pillars should be palpated with the other at the level of the dysfunctional vertebrae. 
3. The patient's head is then placed towards the barrier or in opposition to the diagnosis (ie, if the patient is C4 F Rr Sr, rotate the patient to the left, side bend to the left, and extend). 
4. The patient should attempt to move their head back into a neutral position and provide an isometric force for 3 to 5 seconds.
5. The patient is repositioned further toward the barrier, and step 4 is repeated. 
6. Steps 4 and 5 are repeated 3 to 5 times, and the dysfunction is reevaluated.[21]

Complications

Adverse complications are rare and may include stroke, disc herniation, fractures, or hematomas.[16] In a systematic review, the most frequently described major adverse event was cervical arterial dissection (CAD). However, there is currently insufficient evidence to establish a risk profile for patients susceptible to this complication.[22]

Clinical Significance

This type of osteopathic approach is indicated for vertebral release and muscle relaxation. Very often, the deep muscles of the cervical tract can be a local source of pain and referred pain in the head by irritating the greater occipital nerve. The sub-occipital muscles (3 out of 4) have a myodural bridge, which is innervated and rich in proprioceptors. Contraction of these muscles or the presence of trigger points can cause migraines and headaches. In the acute phase, METs can be performed and relieve symptoms.

The technique stimulates correct intervention of the parasympathetic system and facilitates the restoration of the passage of fluids (blood and lymph). The MET approach can improve the function of the respiratory accessory muscles of the cervical tract, increasing the ventilatory capacity of patients with fibromyalgia.[23]

Chronic neck pain can result from previous trauma; in these cases, the contractile content of the muscles decreases while the fatty tissue increases. This increased fat tissue causes painful local inflammation, and the proprioceptive capacity of the muscular districts decreases with consequent deterioration of the neuromotor coordination. MET can help restore proper spinal joint space and improve muscles' ability to stretch and shorten comprehensively. This last point will allow the neck muscles to implement their function, reducing the causes of the pain.

MET can improve the curvature of the cervical tract, making it a potential therapy for trauma such as whiplash.[24]

Suppose the patient's cervical tract is very painful and not very mobile. In that case, it is possible to start using METs, using the eye muscles in conjunction with the small movements of the head to C2 (oculocephalic reflex).

Enhancing Healthcare Team Outcomes

Muscle energy of the cervical spine is a non-invasive option for patients diagnosed with somatic dysfunctions. While a clinician performs manipulative therapy in an office setting, patient outcomes can be improved by combining exercise with manipulative treatment and employing a multidisciplinary approach. In a systematic review by Hidalgo et al, multiple manipulative treatments combined with exercise were more effective at reducing chronic neck pain than manipulative therapies alone.

Chronic neck pain accounts for 25% of all physiotherapy outpatient visits, and 50% to 85% of these patients report recurrence.[25] Developing a treatment plan with maximum efficacy is imperative to reduce recurrence rates and improve overall patient outcomes.

Nursing, Allied Health, and Interprofessional Team Interventions

The clinician should constantly interact with other health professionals, including the physiotherapist and the speech therapist. In the literature, METs are often combined with non-osteopathic treatments to improve the patient's clinical picture more quickly.

Nursing, Allied Health, and Interprofessional Team Monitoring

Effective osteopathic treatment (in this case, the use of METs) results in a noticeable improvement in the patient's health.