A surface-marker imaging system to measure a moving knee's rotational axis pathway in the sagittal plane

• Published in: IEEE transactions on biomedical engineering Vol. 48; no. 3; pp. 384 - 393
• Main Authors: Moorehead, J.D., Harvey, D.M., Montgomery, S.C.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2001; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adult; Algorithms; Anterior Cruciate Ligament Injuries; Biological and medical sciences; Biomechanical Phenomena; Biomechanics; Data mining; Diagnosis, Computer-Assisted; Diagnostic Imaging - methods; Diseases of the osteoarticular system; Displacement; Humans; Imaging; Juxtaarticular diseases. Extraarticular rhumatism; Kinematics; Knee; Knee Injuries - diagnosis; Knee Joint - physiology; Knees; Leg; Legs; Ligaments; Male; Mathematical models; Medical sciences; Movement - physiology; Orthopedic surgery; Osteoarthritis; Pathways; Planes; Posture - physiology; Reproducibility of Results; Rotation; Rotation measurement; Rotational; Software Design; Software Validation; Sports medicine; Surface Properties; System testing; Juxtaarticular disease; Knee; Human; Diseases of the osteoarticular system; Lower limb; Rotation axis; Cruciate ligament; Marker; Surface analysis; Biomechanics; Tearing; Motion study; Sagittal slice
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/10.914802

Describes a new surface-marker imaging system designed to measure the rotational axis pathway (RAP) of a moving knee in the sagittal plane. Measurement of this parameter can provide important information about a knee's slipping and rolling action that can aid clinical assessment. Seated subjects are video recorded as they actively extend their legs. A series of stills is then captured and analyzed to extract the coordinates of markers plated on the subjects: upper and lower legs. These coordinates are then processed to deduce an instant center of rotation (ICR) for each still. These ICRs are then plotted to derive the joint's RAP. The system has been validated with a mechanical model and tested in a clinical study of ten patients with unilateral anterior cruciate ligament (ACL) ruptures. The study found that the system could consistently measure differences between a patients normal and injured knees. Leg extension caused the normal knees ICRs to displace anteriorly with a mean value of 17.4 mm, whereas the injured knees had a mean displacement of 7.5 mm. This loss of roll in the ACL-deficient knees is consistent with their abnormal biomechanical arrangement.