Common Physical Examination Tests for Patellofemoral Instability Demonstrate Weak Inter-Rater Reliability

Area of Science:

• Orthopaedic surgery
• Sports medicine
• Clinical assessment

Background:

• Recurrent lateral patellofemoral instability is a common condition.
• Accurate physical examination is crucial for diagnosis and management.
• Standardized and reliable assessment tools are needed for clinical practice and research.

Purpose of the Study:

• To evaluate the inter-rater reliability of three common physical examination tests: Q-angle, J-sign, and apprehension test.
• To determine the consistency of these assessments in patients with recurrent lateral patellofemoral instability.

Main Methods:

• A reliability study included 38 subjects with recurrent lateral patellofemoral instability.
• Two orthopaedic surgeons blinded to each other performed bilateral Q-angle, J-sign, and apprehension tests.
• Inter-rater reliability was measured using intraclass correlation coefficient (ICC) for Q-angle and Cohen's kappa for J-sign and apprehension test.

Main Results:

• The Q-angle demonstrated poor reliability (ICC 0.18-0.44).
• The J-sign showed fair to moderate reliability (κ = 0.31-0.41).
• The apprehension test had fair to substantial reliability (κ = 0.30-0.65), with good agreement on apprehension quality.
• All tests exhibited significant variability between right and left limbs.

Conclusions:

• The Q-angle, J-sign, and apprehension tests exhibit weak inter-rater reliability in patients with recurrent lateral patellofemoral instability.
• These findings suggest limitations in using these tests for reliable clinical communication or as outcome measures in research.
• Further investigation into more reliable diagnostic methods is warranted.