# Application of the Gait Kinematics Index in Patients with Cerebral Palsy
## 1 Introduction
The GDI takes into consideration nine variable kinematic values describing a range of angles in the knee, hip, pelvic and tarsal joints [24]. The data are collected every 2% of the gait cycle, which amounts to 459 measuring points for one patient. The calculated GDI value provides information on the difference of the gait of a given patient from a regular gait. The gait of a tested person is similar to the gait of the control group where the GDI \(\geq\) 100, whereas each decrease of 10 in the GDI below 100 indicates one standard deviation from the mean calculated for the control group. The GDI has been applied multiple times to the assessment of locomotive functions in patients with CP [23; 24; 25]. The proposed GKI is based on eleven kinematic parameters recorded during gait examples, and provides information about changes in angles in the ankle, knee joint, hip joint and pelvic movements in three planes. The GKI values were identified on the basis of the GCI\({}_{i}\) assessing locomotor functions at each percentage of the gait cycle. The classification of the GCI\({}_{i}\) values in accordance with the adopted color scale constituted the Gait Deviations Profile. The GDP can be used to indicate a patient's gait deviations from the standard in relation to each percentage of the gait cycle. Such an assessment is not possible using any other index described in available scientific publications. The method also enables a more precise assessment of gait, based on values of KI\({}_{j}\). Indices KI\({}_{j}\) are calculated for each kinematic parameter (P1-P11) as the mean value of standardized angular variables W\({}_{ji}\) related to a given parameter. Indices KI\({}_{j}\) are also classified in accordance with the color scale. A new comprehensive method of gait pathology evaluation (the Gait Kinematics Index, Global Symmetry Index and Gait Deviations Profile) makes it possible to identify gait using a single numerical value, evaluate movements in individual joints and in subsequent moments, as well as to assess the symmetry of gait. A detailed characterization of this gait assessment method in relation to other indicator methods found in the literature is presented in Table 5 in [PERSON] et al. [22]. The GKI is a new indicator that has not yet been used in the clinical evaluation of gait in patients with CP. The only indicator method other than the GKI that allows the assessment of gait on the basis of sub-parameters that characterize the movement in a given joint is the GPS [27]. Partial values of the GPS presented in the form of a MAP (Movement Analysis Profile) are used for the comparison of nine kinematic parameters of the patient's gait (the same as those taken into consideration in the identification of the GDI), with the average values of the aforementioned parameters related to the group of persons with a proper gait. The above-named MAPs are presented in the form of a bar chart, on the basis of which it is possible to indicate deviations from the standard only in relation to a specific joint [22; 27]. The advantages of the gait assessment method proposed by the authors presented in the color scale consist in showing a patient's deviations from the standard gait in each percentage of the gait cycle. Color profiles of deviations from the standard gait are presented in relation to each kinematic parameter (P1-P11) that was subjected to analysis. Such an analysis enables both a detailed and intuitive assessment of the patient's gait kinematics in each joint and at each percentage of the gait cycle [22]. The aim of this study was to assess the clinical utility of the GKI in the population of patients with CP. The possibilities of applying the GKI to a group of patients with CP were evaluated on the grounds of the correlation of its results with the GGI and GDI values. Also, the distribution of its values in terms of CP types and treatment methods was assessed. Our hypothesis was that the GKI values of CP patients would be strongly correlated with the GDI values.