Evaluation Procedure and Interpretation Method for Identifying Dysfunction in Forward Bending Movements

This article summarizes the evaluation procedures and interpretation methods for lumbar pain, buttock pain, radiating pain to the posterior lower limb, and neurological symptoms during forward bending movements.

Symptom reproduction during forward bending is considered to be "flexion pattern type low back pain."
Symptoms are mainly felt during flexion movements, and they are reproduced in semi-crouched postures, standing and sitting movements, and prolonged sitting.

Since this is relatively common in clinical settings, it is crucial to know how to proceed with the evaluation and how to interpret and approach it.

Let's organize our thoughts for each evaluation item and connect them to appropriate interventions!

Evaluation Method for Forward Bending Movements

"What are you observing when you make someone perform a forward bending movement?"

What should you focus on during a forward bending movement?
Is it just about checking for the presence or absence of symptoms?

Measuring the distance to the floor is also important. This evaluates the 'quantity' of the movement.

What I want to convey in this article is the 'quality' of the movement.

When bending forward, it is important to evaluate which part is bending or which part is not bending.

While it also comes with experience, it is crucial to try to observe and develop the ability to see these aspects.

For forward bending evaluation, it is good to refer to the following points.

Evaluation Points on the Sagittal Plane

Let's explain the five points on the sagittal plane.

Smooth Flexion of the Spine

To evaluate whether the spine is bending smoothly, palpate the spinous processes of the spine.
Check for any protruding convex parts or any concave parts.

Convex parts are interpreted as over-flexion, while concave parts are interpreted as flat or extended.

Probably, if there are over-flexed parts, some parts may be flat or extended. It is more common to approach the flat or extended parts rather than the convex parts.

Forward Tilt of the Sacrum

Following that, evaluate whether the sacrum is tilting forward.

If the sacrum is not tilting forward properly, it will hinge between L5 and S1, increasing the burden on surrounding tissues, especially the intervertebral discs.

Distribution of Hip and Spinal Flexion

If the sacrum is tilting forward, it can also be interpreted as the pelvis tilting forward.

This affects the hip flexion movement.

When evaluating forward bending movements, it is important to determine whether it is mainly performed by spinal flexion or hip flexion.

In the case of flexion pattern type low back pain, there is a tendency to perform forward bending movements mainly with spinal flexion.

By considering whether the total amount of flexion is compensated by the spine or the hips, the area of approach changes.

Timing of Hip and Spinal Flexion

Evaluate the timing at which hip and spinal flexion movements occur.

Does it flex only with the spine from start to finish, does it start with the spine and gradually the hips flex, or does it start with the hips and then the spine flexes? Movement patterns vary.

This evaluation is very important for guiding patterned movements to different patterns.

Center of Gravity Position

Finally, regarding the center of gravity position, this refers to the positional relationship between the upper body center of gravity and the lower body center of gravity during forward bending movements.

If hip flexion is minimal and spinal flexion is the main movement, the lower body center of gravity remains unchanged from the upright posture, and only the upper body center of gravity moves forward. In this case, it is a forward center of gravity.

Conversely, if spinal flexion is minimal and hip flexion is the main movement, the buttocks move backward, shifting the lower body center of gravity backward, and the forward movement of the upper body center of gravity is reduced. In this case, the backward center of gravity is stronger.

The main issue is the forward center of gravity, which increases mechanical stress on the lower lumbar region. In the case of a backward center of gravity, smooth spinal flexion is not possible, making it more likely to cause extension pattern type low back pain than flexion pattern type.

Evaluation Points on the Frontal Plane

On the frontal plane, we will explain the following two points.

Since forward bending is a movement on the sagittal plane, it is important to consider issues on the sagittal plane.

However, if there is dysfunction on one side of the sagittal plane, it may cause compensation on the frontal plane.

Lateral Movement of the Pelvis

If there is dysfunction in hip flexion on one side, lateral movement of the pelvis may occur during forward bending movements.

In some cases, compensation may occur through pelvic rotation or a combination of lateral movement and rotation.

For example, if the pelvis moves laterally to the right during forward bending, the right hip flexion increases, while the left hip flexion decreases.

If there is a range of motion limitation in left hip flexion, forward bending will likely avoid hip flexion on the left side.

Of course, it is necessary to consider other evaluations mentioned later in combination with forward bending movements to determine unilateral hip dysfunction.

Lateral Bending of the Spine

If the spinal erector muscles on one side are shortened or tense, or if there is a limitation in the mobility of the facet joints on one side, compensation for lateral bending of the spine may occur.

For example, if the spine bends laterally to the right during forward bending, it suggests a shortening of the right spinal erector muscles. Regarding muscle tension, the left side is tense in a stretched position, while the right side is tense in a shortened position.

When viewed from the dorsal side, there may be a difference in the bulging of the spinal erector muscles, so it is recommended to combine visual inspection and palpation.

If the spine bends laterally to the right, it suggests a limitation in the mobility of the right facet joints. During forward bending movements, the facet joints should allow the upper vertebrae to glide upward and forward relative to the lower vertebrae. If there is a restriction in the right facet joint, the upward glide of the upper vertebrae does not occur, causing the spine to bend laterally as only the left facet joint moves.

Decomposing Forward Bending Movements

Above, we summarized the points for evaluating the quality of forward bending movements, but it is necessary to keep in mind what to evaluate "what" and "how" beyond that.

As you may have noticed from the content so far, forward bending movements can mainly be decomposed into spinal flexion and hip flexion.

Let's explain how to evaluate each of them.

Spinal Flexion

For the evaluation of spinal flexion, consider the following two positions.

In both evaluations, the key point is whether the spine is bending smoothly.

① Seated Spinal Flexion

Spinal flexion movements in a seated position exclude elements distal to the pelvic girdle and allow for the evaluation of spinal flexion mobility with the pelvic girdle stabilized.

Due to the hip flexion position, the stretching limitation of the posterior lower limb muscle group is also excluded.

② Kneeling Spinal Flexion

Spinal flexion movements in a kneeling position are not in an anti-gravity position, unlike in a seated position.

Like in a seated position, the pelvic girdle is stabilized, but the gravitational load on the spine changes, resulting in different muscle activities accompanying the movement. Performing it in a kneeling position allows for the evaluation of pure spinal flexion mobility.

As a side note, the kneeling spinal flexion position is sometimes referred to as the Locking Position / Lumbar Locked Position. It is convenient to remember it as a common language.

Hip Flexion

For the evaluation of hip flexion, consider the following two evaluations.

① SLR

The SLR angle should ideally be 70 degrees for Active and 80 degrees for Passive.

In forward bending movements, the posterior lower limb muscle group is stretched simultaneously on both legs, but SLR allows for the evaluation of the extensibility of the posterior lower limb muscle group on one side.

Therefore, if there is a difference between the left and right sides, it may cause compensation through lateral movement or rotation of the pelvic girdle, and further compensation may lead to lateral bending of the spine.

Additionally, forward bending is a movement under load, but SLR is a movement under non-load. The presence or absence of load changes the feedback, resulting in different muscle activities. If there is dysfunction in the foot or ankle, the muscle tension of the lower limb may increase under load to compensate for stability.

Below are suggestions for the relationship between forward bending and SLR.

② Supine Hip Flexion

The angle for supine hip flexion should ideally be around 100 degrees.
The reference range of motion angle is 125 degrees, but attempting to reach this angle may involve movements of the lumbar and pelvic girdle, so caution is needed.

SLR involves hip flexion in a knee extension position, but supine hip flexion is performed in a knee flexion position. This reduces the influence of the stretching contraction of the posterior lower limb muscles such as the hamstrings and gastrocnemius.

Below are suggestions for the relationship between SLR and supine hip flexion.

In the case of hip flexion mobility limitation, it is necessary to evaluate the range of motion of hip internal and external rotation, accessory motion testing of the femur relative to the ilium, and the evaluation of soft tissues around the hip joint such as the buttocks and groin.

In the case of extensibility limitation of the posterior lower limb muscle group, consider various variations such as whether it is the medial or lateral hamstrings, the medial or lateral gastrocnemius, or the medial or lateral from the hamstrings to the gastrocnemius.

For more detailed information on SLR, please refer to this article.

Comprehensive Summary of SLR Movement Pattern Evaluation, Interpretation, and Differential Methods

What is necessary for evaluating and interpreting SLR movement patterns includes "the influence of the posterior chain and muscle chain," "differences between active and passive movements," "anterior and posterior pelvic tilt," "pre-contraction of the abdominal and core muscles," "influence of the opposite lower limb," and "shortening and relaxation of the hamstrings." This article summarizes the necessary concepts for differentiating the causes of SLR movement dysfunction.

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Summary

Forward bending is a highly versatile evaluation in clinical settings.

Many people are already evaluating the spine and hips that follow. In fact, very few people are unaware of this.

The combination of these evaluations makes it quite clear which areas need intervention.

In clinical settings, the top priority is to shorten the evaluation time as much as possible and connect it to intervention.

By keeping the above content in mind, you can appropriately grasp the dysfunction of the forward bending pattern and speed up the process of leading to improvement if there are symptoms.