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Quantitative assessment of pivot-shift using inertial sensors
Nicola Lopomo1, Cecilia Signorelli, Tommaso Bonanzinga
1Laboratorio di Biomeccanica e Innovazione Tecnologica, Istituto Ortopedico Rizzoli, Via Di Barbiano, 1/10, 40136 Bologna, Italy. n.lopomo@biomec.ior.it
Summary
An inertial sensor accurately quantifies the pivot-shift test for anterior cruciate ligament (ACL) insufficiency. This reliable accelerometer method provides objective dynamic joint laxity assessment, correlating well with navigation systems.
Area of Science:
- Orthopedic Surgery
- Biomechanics
- Medical Instrumentation
Background:
- The pivot-shift test is crucial for diagnosing anterior cruciate ligament (ACL) insufficiency.
- Current pivot-shift testing is subjective and lacks standardized quantitative measurement.
- Objective assessment of dynamic joint laxity is needed.
Purpose of the Study:
- To validate an inertial sensor for quantitative measurement of the pivot-shift test.
- To compare accelerometer-based measurements with a commercial navigation system.
- To assess the reliability and accuracy of inertial sensors in dynamic joint laxity assessment.
Main Methods:
- Intra-operative pivot-shift tests were performed on 15 patients by an expert surgeon.
- Limb kinematics were simultaneously recorded using an accelerometer and a navigation system.
- Anteroposterior tibial acceleration was compared between the two systems, analyzing repeatability and correlation.
Main Results:
- The accelerometer showed good intra-tester repeatability (Cronbach's alpha = 0.86).
- Mean acceleration waveform correlation between patients was high (0.88 ± 0.14).
- A significant positive correlation was found between accelerometer and navigation system measurements (rs = 0.72, P < 0.05).
Conclusions:
- The inertial sensor demonstrated good reliability and accuracy in quantifying the pivot-shift test.
- The accelerometer is a valid tool for objective assessment of dynamic joint laxity.
- This technology offers a promising approach to standardize pivot-shift testing.
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