Joint Angle Variation in Intentional Sit-to-Stand Transitions

Soft tissue artifact is known to be one of the main sources of errors in motion analysis by means of stereophotogrammetry. Among many approaches to reduce such errors, one is to estimate the position of anatomical landmarks during a motion with joint angle or displacement of skin markers, which is the so-called compensation method of anatomical landmarks. The position of anatomical landmarks was modeled from the data of the so-called dynamic calibration, in which anatomical landmark positions are calibrated in an ad hoc motion. This study aimed to apply the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compare their reliability. To compare the methods, two sets of kinematic variables were calculated using two different marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30–60% compared to without compensation. In addition, it had significantly less difference in some kinematic variables (7 of 18) by 25–40% compared to the compensation method with joint angle.

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Measurement of Patellar Proximodistal Positioning with Limited Joint-Angle Sensitivity

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0039-3400230 ◽

2020 ◽

Vol 33 (02) ◽

pp. 096-101

Author(s):

Clara M. Allberg ◽

James Miles

Keyword(s):

Joint Angle ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Reference Intervals ◽

Joint Angles ◽

Angle Variation ◽

Intraclass Correlation Coefficients ◽

Stifle Joint ◽

Wide Range ◽

Coefficients Of Variations

Abstract Objective Patellar luxation can be associated with abnormal proximodistal positioning of the patella. The current gold standard index (Insall–Salvati) for referencing this position is poorly suited to postoperative use, if the tibial tuberosity is moved surgically, but has the advantage of changing minimally with altered joint angles. The aim of this study was to identify an alternative index, which was simple to use, joint-angle insensitive and suitable for postoperative use. Study Design Candidate indices based on the angle between stifle joint landmarks were screened across a wide range of joint angles for insensitivity to joint angle changes using vulpine and canine stifle radiographs. Intraobserver and interobserver agreements were assessed for a single candidate index using canine radiographs. Results An angular index based on the caudal aspect of the femoral and tibial condyles and the apex of the patella was largely insensitive to joint angle variation. Intra- and interobserver agreements appeared suitable for clinical use, with low within-subject standard deviations (<1.3°) and coefficients of variations (<2.2%), and high intraclass correlation coefficients (>0.89). Conclusion Patellar proximodistal position can be acceptably assessed at a variety of caudal joint angles using the described angular index. Further work is required to define reference intervals across a range of canine breeds.

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