Lever sign test: is it sensitive for the diagnosis of anterior cruciate ligament disruption?

High-Precision Wearable Displacement Sensing System for Clinical Diagnosis of Anterior Cruciate Ligament Tears

An anterior cruciate ligament (ACL) tear is a common musculoskeletal injury with a high incidence. Traditional diagnosis employs magnetic response imaging (MRI), physical testing, or other clinical examination, which relies on complex and expensive medical instruments, or individual doctoral experience. Herein, we propose a wearable displacement sensing system based on a grating-structured triboelectric stretch sensor to diagnose the ACL injuries. The stretch sensor exhibits a high resolution (0.2 mm) and outstanding robustness (over 1,000,000 continuous operation cycles). This system is employed in clinical trial to diagnose ACL injuries. It measures the displacement difference between the affected leg and the healthy leg during Lachman test. And when such a difference is greater than 3 mm, the ACL is considered to be at risk for injury or tear. Compared with the gold standard of arthroscopy, the consistency rate of this wearable diagnostic system reached about 85.7%, which is higher than that of the Kneelax3 arthrometer (78.6%) with a large volume. This shows that the wearable system possesses the feasibility to supplement and improve existing arthrometers for facile diagnosing ACL injuries. It may take a promising step for wearable healthcare.

Validity of the lever sign test for the clinical diagnosis of anterior cruciate ligament tears: Assessments in ski resorts

INTRODUCTION

The clinical diagnosis of an anterior cruciate ligament (ACL) tear is based on 3 tests: anterior drawer, pivot shift and Lachman. The latter is the most commonly used test. The "lever sign" is a new clinical test that was first described by Lelli et al. in 2014. The primary objective of this study was to determine the sensitivity of the lever sign test for the clinical diagnosis of ACL tears, in the primary care setting of patients with acute knee injuries. Primary care being the first point of contact between patients and the healthcare system (general practitioners in this study). The secondary objective was to calculate the positive predictive value (PPV) of the lever sign test, by comparing it to the PPV of the Lachman test and its sensitivity. The working hypothesis was that the sensitivity of the lever sign test was equal to or greater than 80%.

METHODS

This prospective cohort study included patients with ski-related knee injuries which occurred in French ski resorts between December 1, 2019, and March 15, 2020. The Lachman test and the lever sign test were performed by 36 mountain physicians and were compared to the magnetic resonance imaging (MRI) findings. The lever sign test involved placing a closed fist under the patient's calf in the supine position and applying downward pressure over the quadriceps. Depending on whether the ACL was intact or not, the patient's heel would either rise off the examination table or remain still. This study included 258 patients: 190 women and 68 men.

RESULTS

The MRIs found 219 ACL tears and 36 intact ACLs. Three MRIs were deemed uninterpretable. The sensitivity of the lever sign test was 61.2% and the PPV was 83.8%. The sensitivity of the Lachman test was 99.1% and the PPV was 86.5%.

CONCLUSION

This study determined the sensitivity of the lever sign test for the clinical diagnosis of ACL tears during real-life situations encountered by mountain physicians. This sensitivity was lower than expected. The Lachman test, on the other hand, showed a very high sensitivity. It remains the test of choice for the clinical diagnosis of ACL tears in patients with knee injuries. Therefore, the lever sign test can complement the Lachman test but is not a substitute for it.

LEVEL OF EVIDENCE

II.