A functional method for estimating the hip joint center of rotation in children with cerebral palsy.

Most clinical gait laboratories utilize the conventional gait model or one of its variants for planning and evaluating treatment in children with cerebral palsy (CP). Estimation of the hip joint center (HJC) is identified as a major source of error that can influence the model outcomes [Peters2010]. Predictive and functional approaches have been proposed in the literature for HJC estimation. Functional approaches are recommended for subjects with adequate hip range of motion (ROM), while predictive approaches are suggested for subjects with limitations in hip ROM, such as children with CP [Kainz2015]. Because functional approaches require multiplane tasks like StarArc movement to calibrate it. Recently, Ravera and Peterson (2021) proposed a regularized version of the well-known symmetric center of rotation estimation method (SCoRE)[Erigh2006] that does not require additional movements for HJC estimation, called RSCoRE. Is it feasible to estimate the HJC in children with CP using RSCoRE without the need for additional functional calibration tasks? This study included 128 individuals with cerebral palsy who visited the Gait and Motion Analysis Lab at Gillette Children's Specialty Healthcare in 2020. As per standard clinical practice, each participant underwent one static trial and five walking trials. Additionally, functional calibration tasks consisting of one trial of two consecutive StarArc movements were conducted for each hip.The Procrustes algorithm was applied to the data to enforce rigid body constraints on segmental markers. The StarArc movement and walking trials were used to perform the SCoRE and RSCoRE methods, respectively. To adapt RSCoRE to CP walking patterns, we included the range variation of each segment in its anisotropic matrix (refer to equation B.4 in Ravera and Peterson (2021)). The accuracy of the functional methods (SCoRE and RSCoRE) was evaluated, and the residual was used to quantify the global accuracy of HJC estimation, as suggested by Ravera et al. (2021). In addition, we computed the predictive approaches proposed by Davis et al. (1991), Harrington et al. (2007), and Hara et al. (2016). HJC estimations were referenced to the pelvis reference system. RSCoRE successfully predicted the hip joint center (HJC) using only walking trials with a global error estimation equivalent to that of SCoRE, as illustrated in Fig. 1. Compared to all predicted approaches, SCoRE predicts a more posterior placement of the HJC, whereas RSCoRE predicts a more external placement. However, both functional approaches placed the HJC at the same height as the predictive approaches. [Display omitted] RSCoRE offers a valuable solution for estimating the HJC in children with CP without requiring potentially challenging calibration movements, as needed by functional approaches. As functional approach, RSCoRE presents similar robustness and accuracy in HJC prediction as functional approaches but uses only gait trials obtained in a standard clinical setting. [ABSTRACT FROM AUTHOR]

Copyright of Gait & Posture is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)