Lumbar Side Bending: Measurement Tools, Techniques, and Clinical Significance

How do you measure lumbar side bending?

Measuring lumbar side bending, also known as lateral flexion, is a crucial component of spinal assessment, primarily performed using objective tools like inclinometers or goniometers, and sometimes indirectly with a tape measure, to quantify the range of motion of the lower back.

Understanding Lumbar Side Bending

Lumbar side bending refers to the movement of the lower spine where the trunk bends laterally to the left or right. This movement is essential for many daily activities, from reaching to the side to maintaining balance.

• Anatomy Involved: The lumbar spine consists of five vertebrae (L1-L5) that articulate with each other via intervertebral discs and facet joints. While the thoracic and cervical regions contribute significantly to overall spinal lateral flexion, true lumbar side bending primarily occurs at the intervertebral joints of the lower back.
• Muscles Responsible: Key muscles facilitating this movement include the quadratus lumborum, internal and external obliques (unilaterally), and portions of the erector spinae group on the contralateral side (to control the movement).
• Importance of Measurement: Assessing lumbar side bending range of motion (ROM) helps in identifying limitations, asymmetries, or hypermobility that could indicate muscle imbalances, joint dysfunction, disc pathology, or neurological compromise. It is vital for baseline assessments, tracking rehabilitation progress, and guiding exercise prescription for fitness enthusiasts and clinical populations alike.

Clinical Measurement Tools

Accurate measurement of lumbar side bending requires specific tools and a standardized approach to ensure reliability and validity.

Inclinometer

The inclinometer is considered one of the most reliable and common tools for measuring spinal ROM, including lumbar side bending. It's a gravity-dependent device that measures the angle of inclination relative to the horizontal plane.

• Principle: The inclinometer uses gravity to determine angular displacement. For lumbar side bending, a single inclinometer can be used, or a dual inclinometer method for more isolated lumbar measurements.
• Procedure (Single Inclinometer):
  1. Patient Positioning: The individual stands upright with feet shoulder-width apart, arms relaxed at their sides.
  2. Placement: Place the inclinometer on the sacrum (S1 or between the posterior superior iliac spines, PSIS) and zero the device.
  3. Second Placement: Move the inclinometer to the spinous process of T12 (thoracolumbar junction) and zero it again. This establishes a baseline for the lumbar segment.
  4. Movement: Instruct the individual to slowly bend directly to the side as far as comfortable, without twisting or leaning forward/backward, and keeping the hips stable.
  5. Reading: At maximal lateral flexion, read the angle on the inclinometer placed at T12. This reading represents the total range of motion of the lumbar spine.
• Pros: High reliability, objective measurement, relatively easy to use after practice.
• Cons: Requires careful placement and stabilization to isolate lumbar movement; can be influenced by pelvic tilt if not properly stabilized.

Goniometer

A goniometer is a widely used tool for measuring joint angles, though its application for isolated lumbar side bending can be less precise than an inclinometer due to the difficulty in identifying clear bony landmarks.

• Principle: Measures angles between two body segments.
• Procedure (Less Common for Isolated Lumbar):
  1. Patient Positioning: Standing upright, as described above.
  2. Axis: Typically placed over the L5-S1 interspace or the sacrum.
  3. Stationary Arm: Aligned with the posterior midline of the sacrum.
  4. Moving Arm: Aligned with the spinous process of T12.
  5. Movement & Reading: Instruct the individual to side bend, and the angle is read at the end range.
• Pros: Readily available, inexpensive.
• Cons: Less reliable for isolated lumbar movement due to difficulty in precise landmark identification and stabilization; often measures total spinal lateral flexion rather than purely lumbar.

Tape Measure (Indirect Method)

The tape measure offers an indirect and less precise method for assessing spinal side bending, but it can be useful for quick screenings or when specialized equipment is unavailable.

• Principle: Measures the change in distance between two points during movement.
• Procedure:
  1. Patient Positioning: Standing upright, feet shoulder-width apart, arms at sides.
  2. Baseline Measurement: Measure the distance from the tip of the middle finger to the floor, or from the greater trochanter to the axilla.
  3. Movement & Measurement: Instruct the individual to slowly side bend as far as possible, keeping the legs straight and hips stable. Re-measure the distance from the fingertip to the floor (or trochanter to axilla) at maximal side bend. The difference between the two measurements indicates the range of motion.
• Pros: Simple, no special equipment needed, practical for quick assessment.
• Cons: Less precise as it doesn't measure angular displacement; influenced by arm length, shoulder girdle movement, and overall spinal mobility (thoracic and cervical contribution); highly susceptible to compensatory movements.

Visual Assessment/Observation

While not quantitative, visual assessment is a crucial initial step to observe the quality and symmetry of movement.

• Procedure: Observe the individual from the front and back as they perform side bending. Look for:
  • Smoothness of movement.
  • Presence of pain or guarding.
  • Compensatory movements (e.g., hip hiking, trunk rotation, knee bending).
  • Symmetry between left and right side bending.
  • The curve of the spine during the movement.
• Pros: Quick, provides qualitative information about movement patterns.
• Cons: Highly subjective, not a quantitative measure of ROM.

Preparation for Measurement

Proper preparation ensures consistent and accurate measurements, regardless of the tool used.

• Patient/Client Positioning: The individual should stand with feet shoulder-width apart, weight evenly distributed, and arms relaxed at their sides. Ensure they are in a neutral spinal position before starting.
• Stabilization: It is critical to stabilize the pelvis to isolate lumbar movement and prevent compensatory hip hiking or rotation. The examiner can gently place their hands on the individual's iliac crests to monitor for unwanted movement.
• Clear Instructions: Provide clear, concise instructions: "Please bend directly to your side, as far as you comfortably can, keeping your chest facing forward and trying not to twist or lean forward/backward." Demonstrate the movement if necessary.
• Repeat Measurements: Take multiple measurements (e.g., 2-3) and average them to increase reliability.

Interpreting Results and Normative Data

Once measurements are taken, interpreting them requires understanding typical ranges and factors that can influence ROM.

• Typical Ranges: Normal lumbar side bending range of motion typically falls within 20-35 degrees to each side. However, these are general guidelines, and individual variations exist.
• Factors Affecting ROM:
  • Age: ROM tends to decrease with age due to disc degeneration and joint stiffness.
  • Sex: Minor differences may exist, but they are generally less significant than other factors.
  • Activity Level: Active individuals often have greater ROM.
  • Spinal Pathology: Conditions like disc herniation, osteoarthritis, scoliosis, or spondylolisthesis can significantly limit or alter side bending.
  • Muscle Tightness/Weakness: Tightness in opposing muscles (e.g., quadratus lumborum on the contralateral side) or weakness in prime movers can restrict movement.
  • Pain: Pain is a significant limiting factor and should always be noted.
• Clinical Significance:
  • Limited ROM: May indicate stiffness, muscle spasm, joint hypomobility, or underlying pathology.
  • Asymmetry: A significant difference between left and right side bending can suggest unilateral muscle imbalances, scoliosis, or a specific injury on one side.
  • Excessive ROM: While less common, hypermobility could indicate ligamentous laxity or instability.

Importance of Accurate Measurement

Accurate and consistent measurement of lumbar side bending is paramount for:

• Establishing Baselines: Creating a starting point for individuals in rehabilitation or training programs.
• Tracking Progress: Objectively monitoring improvements or declines over time.
• Identifying Limitations: Pinpointing specific areas of restricted movement that require intervention.
• Guiding Exercise Prescription: Tailoring exercises to address specific mobility deficits or asymmetries.
• Evaluating Treatment Efficacy: Assessing the effectiveness of interventions like physical therapy or chiropractic care.
• Aiding in Diagnosis: Providing objective data to healthcare professionals to assist in diagnosing spinal conditions.

When to Seek Professional Guidance

While self-assessment can provide some insight, it's crucial to seek guidance from a qualified healthcare professional (e.g., physical therapist, chiropractor, sports medicine physician) if you experience:

• Persistent pain during side bending or other spinal movements.
• Significant limitations in ROM that affect daily activities.
• Noticeable asymmetry in movement.
• Symptoms like numbness, tingling, or weakness in the legs associated with spinal movement.
• Any concerns following an injury or trauma to the back.

Accurate measurement and interpretation of lumbar side bending are vital for maintaining spinal health, optimizing performance, and guiding effective interventions. By understanding the tools and techniques, individuals and professionals can gain valuable insights into the functional status of the lumbar spine.