Construct validity and reliability of tests for sacroiliac dysfunction: standing flexion test (STFT) and sitting...

Area of Science:

• Biomechanics
• Musculoskeletal assessment
• Clinical measurement validation

Background:

• Sacroiliac joint (SIJ) dysfunction involves altered joint motion and positional relationships.
• Clinical tests for SIJ dysfunction often lack established validity and reliability.

Purpose of the Study:

• To evaluate the construct validity and intra- and inter-rater reliability of the standing flexion test (STFT) and sitting flexion test (SIFT).

Main Methods:

• Prospective study with 30 participants and five researchers.
• Evaluations conducted over two days to assess intra- and inter-rater reliability and construct validity.
• 3D motion analysis (BTS SMART-DX system) used as the reference standard for construct validity.

Main Results:

• STFT demonstrated acceptable construct validity (70% agreement, K=0.49) and intra-rater reliability (66.3% agreement, K=0.43).
• SIFT showed poor construct validity (56.7% agreement, K=0.29) and reliability (intra-rater: 56.7% agreement, K=0.38; inter-rater: 13.3% agreement, K=0.01).
• Inter-rater reliability for STFT was very low (10% agreement, K=-0.02).

Conclusions:

• The STFT is a valid and reliable test for assessing SIJ mobility in healthy individuals, even with inexperienced raters.
• The SIFT is not a valid or reliable clinical test for SIJ mobility.
• Further research is recommended for palpatory tests of SIJ mobility, particularly in symptomatic populations.