[The lumbar flexion-relaxation phenomen as a diagnostic test in assessment of lumbar impairment. Sensitivity and specificity].

Objective: To define the role of the flexion-relaxation phenomenon (FRP), assessed through ratios (FRR), as a diagnostic test to define impairment in patients with chronic low back pain (CLBP).
Material and Method: The study sample consisted of 180 participants (16 healthy volunteers and 164 patients on work disability due to CLBP), who were consecutively referred for evaluation at the Biomechanics Laboratory of a workplace accident insurance company from January 2012 to December 2017. The evaluations consisted of an isometric dynamometry test, a kinematic test and assessment of the FRP phenomenon. Minimum criteria were established in the performance of the tests for their acceptance as valid for the study. Lumbar impairment or clinical recovery was defined on the basis of the results of the dynamometry and kinematic tests. The FRP response was assessed with FRRs. A total of 4 different ratios were taken for analysis with ROC curves.
Results: A total of 86 valid tests were obtained (16 classified as lumbar impairment and 71 as recovered cases). The best ratio obtained an area under the ROC curve of 0.87, with a sensitivity of 0.84, a specificity of 0.87, and a positive predictive value of 97%.
Conclusions: The FRP test, along with dynamometry and kinematic evaluations, is effective in identifying lumbar impairment and is the easiest test for patients with CLBP to perform.
(Copyright © 2020 Sociedad Española de Rehabilitación y Medicina Física. Publicado por Elsevier España, S.L.U. All rights reserved.)