Clinical utility of a cluster of tests as a diagnostic support tool for clinical lumbar instability

Abstract

Background: Numerous clinical tests have been proposed for the diagnosis of clinical lumbar instability (CLI), but a cluster of clinical tests is still needed to increase the accuracy of CLI diagnosis.

Objective: To evaluate a diagnostic support tool intended to identify the presence of CLI using a cluster of clinical tests.

Design: Analytical cross-sectional study.

Methods: Two hundred participants with chronic low back pain (LBP) were diagnosed with or without CLI by an orthopedic surgeon. The orthopedic surgeon made the diagnosis from classic clinical symptoms and signs. The diagnosis was used as the reference standard. An orthopedic physical therapist used four clinical tests to identify CLI in each participant, including the apprehension sign, the instability catch sign with/without the abdominal drawing-in maneuver (ADIM), the painful catch sign with/without the ADIM, and the prone instability test.

Results: For an individual test, the apprehension sign showed a high specificity (92.6%) and a positive likelihood ratio (LR+; 2.4) but a very low sensitivity of 17.4%. A cluster of three of the four examined tests provided the most diagnostic accuracy for CLI, with a high LR+ (5.8) and a high specificity (91.7%) but low sensitivity (47.8%) and a negative likelihood ratio (LR-; 0.6).

Conclusions: A cluster of three of the four examined tests was determined to comprise a powerful clinical support tool for the identification of CLI patients as tested against a reference standard diagnosis.

Clinical trial registration: Name of the registry: Thai Clinical Trials Registry. Registration number: TCTR20190426002.

Keywords: Diagnostic test; Functional lumbar instability; Lumbar spine.