Association between changes in pain or function scores and changes in scapular rotation

Key points

1. 01No significant correlation was found between changes in pain (NPRS) and changes in scapular rotation at 60, 90, or 120 degrees of arm elevation (rs = 0.03 to 0.27).
2. 02No significant correlation was found between changes in function (PSFS) and changes in scapular rotation at any angle (rs = -0.13 to 0.23).
3. 03Pain improved slightly over 8 weeks (mean decrease ~1.1 points on NPRS) and function improved (mean PSFS increase 9.2 points), but these changes were below or at the minimal clinically important difference.
4. 04Most participants did not receive formal treatment, limiting the range of clinical change observed.
5. 05Scapular dyskinesis may be one of many contributing factors to shoulder pain rather than a direct driver of symptoms.

How it was conducted

Design

Prospective observational cohort study with 8-week follow-up

Participants

25 adults (16 women, 9 men; age 24-86 years) with subacromial shoulder pain; 80% had chronic pain (>3 months)

Primary outcome

Spearman rank correlation between changes in NPRS/PSFS scores and changes in scapular rotations

Pain measure

Numeric Pain Rating Scale (NPRS) at 60, 90, and 120 degrees of scapular arm elevation

Function measure

Patient Specific Functional Scale (PSFS)

Scapular measurement

Scapular locator with inertial sensors measuring upward/downward rotation and anterior/posterior tilt (ICC 0.73-0.93); internal/external rotation excluded due to poor reliability (ICC 0.37-0.62)

What they found

• Scapular upward/downward rotation correlations with pain change: rs = 0.03 (p=0.888) at 60 degrees, rs = 0.27 (p=0.190) at 90 degrees, rs = 0.15 (p=0.472) at 120 degrees.
• Scapular anterior/posterior tilt correlations with pain change: rs = -0.01 (p=0.968) at 60 degrees, rs = 0.23 (p=0.268) at 90 degrees, rs = 0.09 (p=0.666) at 120 degrees.
• Scapular upward/downward rotation correlations with function change: rs = 0.23 (p=0.271) at 60 degrees, rs = -0.13 (p=0.548) at 90 degrees, rs = -0.09 (p=0.659) at 120 degrees.
• Scapular anterior/posterior tilt correlations with function change: rs = -0.05 (p=0.808) at 60 degrees, rs = 0.08 (p=0.718) at 90 degrees, rs = -0.13 (p=0.540) at 120 degrees.
• NPRS improved significantly at all angles: mean difference -1.1 (95% CI -2.0 to -0.2, p=0.022) at 60 degrees, -0.9 (95% CI -1.5 to -0.2, p=0.013) at 90 degrees, -1.1 (95% CI -1.9 to -0.2, p=0.018) at 120 degrees.
• PSFS improved significantly: mean difference 9.2 (95% CI 2.2 to 16.1, p=0.012).
• Scapular posterior tilt at 120 degrees changed significantly: mean difference 6.9 degrees (95% CI 0.2 to 13.7, p=0.042); no other scapular rotation changes were statistically significant.

Limitations

• Very small sample (n=25 at baseline, n=20 at follow-up) with limited statistical power to detect weak-to-moderate correlations.
• Most participants did not receive treatment, so pain and function changes were minimal and may not reflect a clinically meaningful range of change.
• Scapular internal/external rotation could not be assessed due to poor reliability of the measurement tool in that plane.
• Potential confounders such as symptom duration, age, sex, pain catastrophizing, and physical demands were not controlled for.

Why it matters

For patients

People with shoulder pain should not assume their symptoms will only improve if their shoulder blade movement is corrected, as pain and function can change independently of scapular rotation.

For clinicians

Targeting scapular dyskinesis in isolation may not be sufficient; a multifactorial approach addressing pain, strength, psychosocial factors, and activity demands is warranted.

For readers

This study questions a common clinical assumption and highlights the need for larger, controlled studies that examine multiple contributing factors to subacromial shoulder pain simultaneously.