Pelvic Tilt: Understanding, Goniometer Measurement, and Interpretation

How do you measure pelvic tilt with a goniometer?

Measuring pelvic tilt with a goniometer involves precisely aligning the instrument's arms with specific anatomical landmarks, typically on the sacrum, to quantify the angle of the pelvis relative to a horizontal reference, thereby indicating anterior or posterior inclination.

Understanding Pelvic Tilt and Its Significance

Pelvic tilt refers to the orientation of the pelvis in the sagittal plane, specifically its anterior (forward) or posterior (backward) rotation. This seemingly subtle angle has profound implications for overall posture, spinal alignment, movement efficiency, and the potential for musculoskeletal pain.

• Anterior Pelvic Tilt: Characterized by the top of the pelvis tilting forward, increasing the lumbar lordosis (inward curve of the lower back) and often associated with shortened hip flexors and lengthened hamstrings/glutes.
• Posterior Pelvic Tilt: Characterized by the top of the pelvis tilting backward, flattening the lumbar spine and often associated with shortened hamstrings/glutes and lengthened hip flexors.

Accurate measurement of pelvic tilt is crucial for fitness professionals, physical therapists, and kinesiologists to identify postural imbalances, design targeted corrective exercise programs, and monitor progress. While inclinometers are often preferred for their ease of use, a goniometer can be effectively employed with proper technique.

What You'll Need

To accurately measure pelvic tilt using a goniometer, ensure you have the following:

• Large Goniometer (360-degree): A goniometer with clear markings and a stable fulcrum is essential. A larger instrument (e.g., 12-14 inches) provides greater precision.
• Subject/Client: Appropriately dressed in form-fitting clothing that allows for palpation of bony landmarks without obstruction.
• Plumb Line or Spirit Level (Optional but Recommended): To ensure the stationary arm of the goniometer is truly horizontal.
• Marking Pen (Optional): To temporarily mark anatomical landmarks, improving consistency.

Anatomical Landmarks for Measurement

For goniometric measurement of pelvic tilt, particularly using the sacral angle method (a common and reliable approach), the primary landmark is the second sacral segment (S2).

• Locating S2:
  • Have the client stand comfortably.
  • Palpate along the midline of the lower back, just above the gluteal cleft.
  • The posterior superior iliac spines (PSIS) are typically level with S2 or slightly superior to it.
  • S2 is located in the midline of the sacrum, approximately at the level of the dimples of Venus (if present). It represents the approximate center of the sacrum's posterior surface.

Step-by-Step Measurement Procedure (Sacral Angle Method)

This method measures the angle of the sacrum relative to the horizontal, providing a direct indication of pelvic inclination.

• Step 1: Client Positioning

  • Have the client stand upright in a relaxed, natural posture. Ensure their feet are shoulder-width apart and weight is evenly distributed.
  • Instruct them to look straight ahead and breathe normally. Avoid any forced or exaggerated posture.

• Step 2: Locate and Mark S2

  • Carefully palpate the S2 segment on the client's sacrum. If desired, use a washable marking pen to place a small dot on this landmark for consistent reference.

• Step 3: Position the Goniometer

  • Fulcrum: Place the fulcrum (pivot point) of the goniometer directly over the marked S2 landmark.
  • Stationary Arm: Align the stationary arm of the goniometer horizontally, ensuring it is parallel to the floor. You can use a spirit level on the goniometer arm or visually align it with a horizontal reference point in the room.
  • Moving Arm: Align the moving arm of the goniometer parallel to the long axis of the sacrum. This often means aligning it along the midline of the sacrum, extending inferiorly towards the coccyx.

• Step 4: Read the Measurement

  • Once the goniometer is correctly positioned, read the angle indicated on the scale. This angle represents the sacral inclination.

Interpreting the Measurement

The sacral angle provides valuable insight into pelvic tilt:

• Normal Range: A typically healthy sacral angle in standing is generally considered to be between 30-45 degrees relative to the horizontal.
• Anterior Pelvic Tilt: An angle greater than 45 degrees suggests an anterior pelvic tilt. The sacrum is tilted further forward, increasing the lumbar curve.
• Posterior Pelvic Tilt: An angle less than 30 degrees suggests a posterior pelvic tilt. The sacrum is tilted backward, potentially flattening the lumbar curve.

Remember that these are general guidelines. The "ideal" pelvic tilt can vary slightly based on individual anatomy, activity level, and specific movement demands. Always interpret the measurement in the context of a comprehensive postural and movement assessment.

Tips for Accuracy and Reliability

• Consistent Landmark Palpation: Practice palpating S2 until you can locate it quickly and consistently.
• Proper Client Positioning: Ensure the client maintains a relaxed, natural standing posture throughout the measurement. Any shifting or tensing can alter the reading.
• Multiple Measurements: Take 2-3 measurements and average them to increase reliability.
• Minimize Clothing Interference: Loose or bulky clothing can obscure landmarks and interfere with goniometer placement.
• Goniometer Type: A clear plastic goniometer allows you to see the landmarks beneath the instrument.
• Lighting: Ensure good lighting to clearly see landmarks and goniometer markings.

Limitations of Goniometric Measurement

While a valuable tool, goniometric measurement of pelvic tilt has limitations:

• Subjectivity: Landmark palpation can be subjective, leading to inter-rater (between different examiners) and intra-rater (by the same examiner) variability.
• Experience Dependent: Accuracy improves significantly with practice and experience.
• Not Standalone: Pelvic tilt should always be assessed in conjunction with other postural and movement analyses (e.g., hip range of motion, core strength, gait analysis) to gain a complete picture.
• Indirect Measure: While the sacral angle is a strong indicator, it's an indirect measure of the entire pelvic block's tilt, which is influenced by multiple joints and muscles.

When to Seek Professional Guidance

While measuring pelvic tilt can provide useful information for fitness and health enthusiasts, it's crucial to understand that it's an assessment tool, not a diagnostic one. If you experience persistent pain, significant postural deviations, or difficulty with movement, consult with a qualified healthcare professional such as a physical therapist, chiropractor, or physician. They can provide a comprehensive diagnosis and develop an appropriate treatment plan tailored to your specific needs.