Evaluation of clinical tests to diagnose iliopsoas tendinopathy

Key points

1. 01The HEC test combines hip flexion with external rotation and outperformed all conventional tests with an AUC of 0.99 (95% CI 0.98 to 1.00)
2. 02Three tests met all criteria for a 'good' diagnostic test: HEC, resisted hip flexion (seated), and resisted hip external rotation (seated)
3. 03The Thomas test, HEER test, and SLR in neutral were classified as 'poor' tests, failing all three performance criteria
4. 0482% of 44 patients (36) were confirmed to have iliopsoas tendinopathy via fluoroscopy-guided anesthetic injection
5. 05The HEC test pain reduction cutoff of VAS 5 points provided the best balance of sensitivity and specificity

How it was conducted

Design

Retrospective diagnostic accuracy study

Participants

44 patients (mean age 48 +/- 15 years; 34% male) with persistent groin pain refractory to 3+ months of physiotherapy

Hip types

52% native hips, 48% post-total hip arthroplasty

Index tests

11 physical examination tests: the novel HEC test plus 10 conventional tests

Reference standard

Fluoroscopy-guided peritendinous iliopsoas injection; pain relief at 2 hours (binary satisfied/unsatisfied scale)

Setting

Single high-volume arthroplasty community hospital, Belgium, October 2023 to May 2024

What they found

• 82% (36 of 44) of patients had satisfactory pain reduction after injection and were diagnosed with iliopsoas tendinopathy
• HEC test: mean VAS pain reduction 6.0 +/- 2.1 (p < 0.001); sensitivity 94%, specificity 88%, AUC 0.99 (95% CI 0.98 to 1.00), optimal cutoff VAS reduction of 5
• Resisted hip flexion (seated): mean VAS reduction 5.1 +/- 1.3 (p < 0.001); sensitivity 94%, specificity 89%, AUC 0.96 (95% CI 0.88 to 1.00)
• Resisted hip external rotation (seated): mean VAS reduction 3.5 +/- 2.0 (p = 0.046); sensitivity 96%, specificity 81%, AUC 0.98 (95% CI 0.92 to 1.00)
• SLR in external rotation: mean VAS reduction 4.9 +/- 1.4 (p < 0.001); AUC 0.88 (95% CI 0.72 to 0.98); sensitivity 78%, specificity 80%
• SLR in neutral: mean VAS reduction 3.8 +/- 1.5 (p < 0.001); AUC 0.72 (95% CI 0.53 to 0.88); sensitivity 80%, specificity 50%
• Thomas test: mean VAS reduction 1.2 (95% CI 0.8 to 1.7); AUC 0.70 (95% CI 0.46 to 0.92); sensitivity 100%, specificity 44%; classified as 'poor' test
• FADIR: mean VAS reduction 0.8 (95% CI 0.4 to 1.1); AUC 0.84 (95% CI 0.73 to 0.93); classified as 'poor' by all three criteria
• 16% (7 of 44) dissatisfied patients responded to intraarticular injection and were diagnosed with labral tears; 1 had rectus femoris avulsion

Limitations

• Small sample (44 patients) at a single centre with a retrospective design, limiting generalisability
• The gold standard injection may not be fully specific: the iliopsoas bursa communicates with the native hip joint in up to 15% of people, and marcaine could theoretically diffuse through the capsule
• Only patients with refractory, severe groin pain who proceeded to injection were studied, so findings may not apply to milder presentations
• Intraobserver and interobserver reliability of the HEC test have not been evaluated, and sex-disaggregated analysis was omitted due to small sample size

Why it matters

For patients

Patients with persistent groin pain may benefit from a specific physical examination test (the HEC test) that can guide diagnosis without immediately needing an invasive injection.

For clinicians

The HEC test should be considered part of routine hip evaluation for suspected iliopsoas tendinopathy, as it outperforms all conventional tests and may reduce unnecessary diagnostic injections; the Thomas test and SLR in neutral offer little diagnostic value for this condition.

For readers

This study provides the first ranked comparison of 11 clinical tests for iliopsoas tendinopathy with a validated injection reference standard, introducing a novel maneuver with excellent diagnostic metrics, though the small single-centre sample warrants independent replication.