Outcome evaluation of surgery treatment by means of gait analysis in children with cerebral palsy: the normality pattern is not an effective term of comparison

INTRODUCTION: Among the treatments available for the rehabilitation of the alterations of walking in children affected by Cerebral Palsy (CP), multilevel surgery is one of the most effective and used solutions despite its irreversible nature. Increasingly literature provides evidences of the large benefits afforded by Gait Analysis (GA) in the process of surgery decision making and in the choice of the most appropriate surgery tecnique [1]. However, besides the diagnostic process, GA can be used in order to measure accurately and effectively the outcome of the treatment [1]. The aim of the present study is to demonstrate how deviations in the kinematic pattern of walking provoked by a surgery treatment can determine i) an improvement in the motor performance and ii) an increase in the autonomy level in action, also when they vary in the opposite direction with respect to the normal pattern.METHODS: 15 dipelgic children with purely spastic forms of CP (age range 7 – 17 years) classified in one of the four forms of diplegia proposed by [2] and addressed by a clinical examination to undergo a functional surgery treatment on the lower limbs, participated in the study. The aim of the surgery treatment was to improve the motor performance and the autonomy level in walking. The treatments adopdet included tendon and muscolar lengthenings, and interventions of skeleton correction. The motor performance exhibited by the subjects was measured both by means of the Gross Motor Function Measure 88 (GMFM) by using merely the dimension D and E [3], and of GA, the day before (session PRE) and after six months (session POST) the surgery intervention. The kinematic of at least three gait cycles for each limb was acquired through the protocol Total3DGait [4] by means of an 8 cameras Vicon MX+ system (Vicon Motion System, UK). The 9 kinematic variables relative to the sagittal, frontal and transverse plane rotations of the hip, knee and ankle and the 4 relative to the rotations on the sagittal and frontal plane of the segments pelvis and trunk obtained during the PRE and POST sessions were compared with respect to the normality bands [4]. In particular, for each of the 13 kinematic variables considered, set of 3 mean waveforms were computed from the gait cycles acquired in the two sessions PRE and POST and from the normality bands. For each subject, the approach of the 13 mean waveforms of the POST session towards the normality, with respect to the ones of the session PRE, was computed in terms of offset (Off) and Range of Movement (ROM). In particular, positive values of Off and ROM indicate an approach of the POST mean waveforms to the normal ones in the absolute and range terms. RESULTS: The GMFM values obtained were positive in 13 cases over 15, with a percentage mean value of 3.4 and a standard deviation of 6.1. The following table reports the mean and the standard deviation values relative to Off and ROM obtained from the 13 kinematics variable considered for each of the 15 subjects enrolled. p1p2p3p4p5p6p7p8p9p10p11p12p13p14p15ROMmean-0.3-1.60.4-0.70.22.11.3-0.5-0.31.8-0.50.8-0.91.50.2sd3.36.64.09.04.25.76.12.56.43.73.65.54.62.74.3Offmean0.3-2.00.20.9-0.33.3-0.60.53.23.72.6-0.11.11.4-0.2sd5.85.16.44.95.98.25.53.08.414.96.95.47.66.24.1Table 1: mean and standard deviations (sd) values obtained for Off and ROM over the 13 kinematics variables considered for the 15 subjects (p1 – p15).DISCUSSION: The GMFM data obtained revealed an improvement in the autonomy level in action in 13 cases over 15. On the contrary, the elevated values of the standard deviations together with mean values close to 0 of Off and ROM parameters, demonstrate that the kinematic waveforms obtained in the POST session did not approach the normality pattern homogeneously a