Comfort and Preference during Prone Upper Thoracic Spinal Manipulation in Various Head Positions

Technical Summary: Comfort and Preference during Prone Upper Thoracic Spinal Manipulation in Various Head Positions

Problem Statement
Spinal manipulation therapy (SMT) is a recommended treatment for neck pain, with specific benefits noted for procedures targeting the thoracic spine. While predictors of positive outcomes include patient preference and comfort, these factors remain under-researched regarding the specific mechanics of how SMT is performed. Specifically, the effect of head rotation position during a prone upper thoracic hypothenar transverse push—a common technique for treating neck pain—on patient comfort and preference has not been previously studied. Current literature focuses heavily on clinical outcomes (pain, disability) and biomechanics, leaving a gap in understanding how setup variations influence the patient experience.

Methodology
The study employed an experimental, cross-sectional, within-subject design involving 91 healthy adult volunteers (mean age 26.0 ± 5.3 years; 43% female) recruited from June to December 2024 at the Canadian Memorial Chiropractic College (CMCC).

• Intervention: Each participant received four SMT procedures targeting the upper thoracic spine (T2) using a prone hypothenar transverse push.
• Independent Variable: Head rotation positions were standardized in a non-randomized order (to mitigate potential order effects related to cavitation likelihood) progressing from:
  1. Neutral
  2. 33% of maximal passive range of motion (ROM)
  3. 66% of maximal passive ROM
  4. 100% of maximal passive ROM
  • Procedures were performed on alternating sides (left/right) with a target peak force of 700 N (±50 N), delivered by a single licensed chiropractor with 16 years of experience.
• Data Collection:
  • Biomechanics: Force-time profiles were recorded using Force Sensing Table Technology (FSTT®) to ensure consistency.
  • Subjective Measures: Post-procedure questionnaires utilized Visual Analog Scales (VAS) to assess:
    • Overall rating of the procedure.
    • Comfort/discomfort levels.
    • Perceived pressure on the head.
    • Preference (binary choice of the most preferred procedure).
• Statistical Analysis: Comfort and overall ratings were analyzed using Kruskal–Wallis rank-sum tests with post hoc pairwise comparisons (Bonferroni adjustment). Preference was analyzed using Chi-squared tests with pairwise proportion tests.

Key Results

• Force Consistency: The applied force was consistent across all procedures, with a mean total peak force of 685.1 N (±89.0).
• Head Pressure: Reported head pressure increased linearly with rotation, rising from a mean of 17.5 (neutral) to 31.0 (100% rotation) on a 0–100 scale.
• Preference: Head position significantly influenced preference ($\chi^2$=16.5, $p$=0.0009). The 100% rotation position was significantly less preferred than the neutral position ($p$=0.0006).
• Comfort: Comfort ratings were significantly lower at 66% ($p$=0.01) and 100% ($p$<0.0001) rotation compared to neutral. Additionally, 100% rotation was less comfortable than 33% rotation ($p$=0.023).
• Overall Rating: Similar to comfort, overall ratings for 100% rotation were significantly lower than neutral ($p$=0.0007) and 33% rotation ($p$=0.042).
• Adverse Events: Eight mild, transient adverse events were reported (seven instances of soreness/mild pain, one headache, and one report of transient neck restriction). No events required intervention.

Significance and Claims
The paper concludes that head rotation position is a significant factor influencing reported comfort, preference, and overall ratings during prone upper thoracic SMT. The authors claim that:

1. Neutral Positioning is Optimal for Most: The neutral head position consistently yielded the most positive responses across all measured outcomes.
2. Maximal Rotation is Less Favorable: Increasing head rotation to maximal levels (100% ROM) is associated with reduced comfort and lower preference, potentially due to increased perceived head pressure or the mechanics of the position itself.
3. Individual Variability Exists: Despite the general trend favoring neutral positioning, a subset of participants preferred greater rotation, highlighting the importance of individual differences.
4. Clinical and Educational Implications: The findings suggest that modifying head positioning based on individual patient needs may improve the patient experience. This offers guidance for teaching and clinical practice, aligning with the principles of patient-centered care in manual therapy.

The authors maintain a modest scope, acknowledging that the study was limited to asymptomatic young adults and a single practitioner/technique. They do not claim that these findings directly alter clinical efficacy (pain reduction) but rather focus on the patient experience and preference as a component of care delivery.