Objective. Evaluation of the effectiveness of the criteria for diagnosing ligamenthosis of iliolumbar ligament, posterior long sacroiliac ligament and sacrotuberous ligament in case of lower back pain syndrome.

Materials and methods. The results of sonography and diagnostic blockades comparing allowed evaluate the specificity and sensitivity of the criteria used for ligamenthosis diagnosis in case of the lower back pain in relation to iliolumbar ligament, posterior long sacroiliac ligament, and sacrotuberous ligament among 135 patients (men — 33, women — 102, age — 17 — 74 yrs).

Results. The high sensitivity and specificity of the “thickness difference of the comparable segments of the contralateral ligaments” criterion were confirmed: for the iliolumbar ligaments (at a difference ³30%) — 77.0 and 96.0, respectively; for the long dorsal sacroiliac ligaments (at a difference ³20%) — 82.0 and 96.0, respectively; for the sacrotuberous ligaments (at a difference ³20%) — 80.8 and 85.0, respectively.

Conclusion. The criterion “severity of the contralateral ligaments asymmetry” has good sensitivity, specificity, prognostic values and reproducibility making possible recommend it for use in clinical practice.