Understanding Pelvic Torsion Through PSIS Palpation and Blocking Preferences in Chiropractic Techniques

Pelvic torsion, a condition where the innominate bones rotate in opposite directions, can affect posture, movement, and overall spinal health. Chiropractors often use various methods to identify and correct this misalignment. One technique involves blocking the pelvis with padded wedges, a method closely linked to the Sacro-occipital Technique. Traditionally, practitioners identify pelvic torsion by checking leg length discrepancies in a prone position. However, a study by Cooperstein et al. (2004) explored a more direct approach: palpating the posterior superior iliac spines (PSIS) while the patient is seated, and examining how this relates to blocking preferences.

This post breaks down the study’s findings and explains how PSIS palpation can offer a practical way to assess pelvic torsion and guide treatment choices.

What Is Pelvic Torsion and Why Does It Matter?

Pelvic torsion occurs when one innominate bone (part of the pelvis) rotates backward while the other rotates forward. This rotation can cause one leg to appear shorter when the patient lies face down. Such asymmetry can lead to uneven weight distribution, muscle imbalances, and strain on the lower back and hips.

Chiropractors aim to correct this torsion to restore balance and reduce discomfort. Identifying the direction of torsion is essential for effective treatment. For example, a left posterior-inferior ilium (left PI) means the left innominate bone has rotated backward and downward.

Traditional Method: Prone Leg Check

The prone leg check is a common way to detect pelvic torsion. The patient lies face down, and the practitioner observes leg length differences. A shorter leg is thought to indicate the side with posterior ilium rotation. While widely used, this method is indirect and can be influenced by factors other than pelvic torsion, such as muscle tightness or joint restrictions.

Direct Approach: Sitting PSIS Palpation

The study by Cooperstein and colleagues tested a direct method by palpating the PSIS while participants were seated. The PSIS are bony landmarks on the back of the pelvis, and their relative positions can indicate pelvic torsion. A lower PSIS on one side suggests that side’s ilium is rotated posteriorly.

In this study, 28 asymptomatic participants were examined by two investigators. One palpated the PSIS for asymmetry, and the other tested blocking preferences using padded wedges placed under specific pelvic points.

Blocking Technique and Preferences

Blocking involves placing padded wedges under the pelvis to encourage correction of torsion. In this study, one block was placed under the left anterior superior iliac spine (ASIS) and the other under the right greater trochanteric area. Then the blocks were switched to the opposite sides. Participants were observed for which blocking pattern felt more comfortable or preferable.

This preference is believed to reflect the direction of pelvic torsion. For example, a person with a right posterior-inferior ilium (right PI) might prefer a blocking pattern that supports correction of that torsion.

Key Findings from the Study

• Out of 26 participants with palpable PSIS, 21 showed a clear blocking preference.

• 16 preferred a blocking pattern that would correct a right PI.

• 5 preferred a pattern for a left PI.

• 12 participants had a lower PSIS on the right side, indicating right PI.

• 4 had a lower PSIS on the left side, indicating left PI.

• 8 were judged symmetric with no clear PSIS asymmetry.

• Among 14 participants with both PSIS asymmetry and a clear blocking preference, 9 showed agreement on the right side, 3 on the left side, and 2 did not match.

  
  

These results suggest a strong relationship between PSIS position and blocking preference, supporting the use of sitting PSIS palpation as a reliable way to identify pelvic torsion.

Understanding Pelvic Torsion Through PSIS Palpation and Blocking Preferences in Chiropractic Techniques: Practical Implications for Chiropractic Care

Using sitting PSIS palpation offers several advantages:

• Direct assessment: Palpating the PSIS provides immediate information about pelvic alignment without relying on indirect signs like leg length.

• Patient comfort: Sitting position is often easier and more comfortable for patients compared to prone assessments.

• Guiding treatment: Blocking preferences can help chiropractors choose the most effective wedge placement to correct torsion.

• Improved accuracy: Combining PSIS palpation with blocking tests may increase confidence in diagnosis and treatment planning.

  
  

For example, a chiropractor might find a patient’s right PSIS lower than the left while seated. The patient then prefers a blocking pattern that supports correction of a right PI. This concordance confirms the diagnosis and guides wedge placement during treatment.

Limitations and Considerations

While the study provides valuable insights, it involved a small sample of asymptomatic individuals. Results might differ in patients with pain or other musculoskeletal issues. Also, two participants showed discordance between PSIS palpation and blocking preference, reminding practitioners to consider multiple assessment methods.

Chiropractors should use PSIS palpation as part of a comprehensive evaluation, including patient history, movement analysis, and other physical tests.

Summary

The study by Cooperstein et al. highlights the value of sitting PSIS palpation in identifying pelvic torsion. This direct method correlates well with blocking preferences, a technique used to correct pelvic misalignment. For chiropractors, incorporating PSIS palpation can enhance assessment accuracy and improve treatment outcomes.

If you are a practitioner or student interested in pelvic mechanics, consider adding sitting PSIS palpation and blocking preference testing to your toolkit. These methods offer clear, practical ways to understand and address pelvic torsion, supporting better patient care and spinal health.

Cooperstein R, Crum E, Morschhauser E, Lisi A, Sitting PSIS Positions and Prone Blocking Preferences The Journal of Chiropractic Education Spr 2004; 18(1): 44-5.

Blocking the pelvis with padded wedges, a technique procedure most closely identified with Sacro-occipital Technique, is believed to correct pelvic torsion, in which the innominate bones have rotated in opposed directions.  The direction of pelvic torsion (e.g., left posterior-inferior ilium, or left PI) is identified by a prone leg check, where the short leg is thought to identify relatively posterior ilium rotation.  This study used the direct approach of sitting PSIS palpation to identify pelvic torsion, rather than the more typically used and indirect approach of leg checking.  This study also tested the assumption that blocking preferences are related to pelvic torsional patterns as assessed by PSIS palpation.

METHODS:  In a 28-subject study, investigator 1 palpated each of these asymptomatic participants in the seated position for evidence of PSIS positional asymmetry.  Immediately following, investigator 2 examined each of the participants for blocking preferences.  One block was inserted under the left ASIS and the other under the right greater trochanteric area, after which the blocks were removed and reinserted in the opposite pattern.

RESULTS:  Of the 26 study participants whose PSISs were palpable, 21 exhibited preferences for one of the blocking patterns, and three did not:  16 preferred a pattern corrective of a right PI, and five preferred a pattern for a left PI.  Twelve had a lower PSIS on the right (thought to identify right PI), four had a low PSIS on the left (thought to identify left PI), and eight were judged symmetric.  A subset of 14 participants had both PSIS asymmetry and a clear blocking preference.  Of these, nine showed concordant right-sided PSIS calls and blocking preferences, three showed left-sided concordance and two were not concordant.  Thus, 12 of the 14 study participants showed a concordant pattern of PSIS asymmetry and blocking preferences.

DISCUSSION:  Since the incidence of anatomic leg-length inequality (LLI) of _ inch or more is a much as 50% in asymptomatic subjects, leg checking procedures may not be able to distinguish the functional short leg thought to be associated with posterior innominate rotation from anatomic LLI.  Moreover, an anatomic short leg has been found associated with anterior innominate rotation, and anatomic long leg with posterior innominate rotation.  Therefore, we decided against using leg checking to identify pelvic torsion, and used instead static palpation of the pelvis in the seated position.  Given the evidence that congenital asymmetry of the innominate bones is minimal, it is likely that PSIS asymmetry reflects pelvic subluxation rather that innominate dysplasia.  The high degree of concordance (Kappa = .65, CI = 0.5) found in this study between inferred pelvic torsion and corrective blocking preferences suggests that blocking subjects might predict positive clinical outcomes in a program of chiropractic care.  The relatively wide confidence interval for the Kappa statistic suggests the need for a larger data set.

CONCLUSION:  The results of provocation prone pelvic blocking and seated PSIS palpation were strongly concordant in this preliminary study.  If the current findings are substantiated.  Sacro-occipital Technique and other practitioners may consider the manner in which they obtain their indications for pelvic blocking.