An Unsupervised Data-Driven Model to Classify Gait Patterns in Children with Cerebral Palsy

Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is unclear whether 3D gait analysis (3DGA) provides sufficient and reliable information for clinicians to be consistent when prescribing orthoses. Data-driven modeling can probe such questions by revealing non-intuitive relationships between variables such as 3DGA parameters and gait outcomes of orthoses use. The purpose of this study was to (1) develop a data-driven model to classify children with CP according to their gait biomechanics and (2) identify relationships between orthotics types and gait patterns. 3DGA data were acquired from walking trials of 25 typically developed children and 98 children with CP with additional prescribed orthoses. An unsupervised self-organizing map followed by k-means clustering was developed to group different gait patterns based on children’s 3DGA. Model inputs were gait variable scores (GVSs) extracted from the gait profile score, measuring root mean square differences from TD children’s gait cycle. The model identified five pathological gait patterns with statistical differences in GVSs. Only 43% of children improved their gait pattern when wearing an orthosis. Orthotics prescriptions were variable even in children with similar gait patterns. This study suggests that quantitative data-driven approaches may provide more clarity and specificity to support orthotics prescription.

Static and dynamic pelvic kinematics after one-stage bilateral or unilateral total hip arthroplasty

Introduction: The pelvis rotates simultaneously around both hips along sagittal, frontal and transversal planes and its kinematics change in patients after total hip arthroplasty (THA). Consequently, it is reasonable to expect different pelvic kinematic profiles in bilateral or unilateral THA. Therefore, the aim of this study was to compare pelvic kinematics in patients with bilateral or unilateral THA. Methods: 40 patients undergoing bilateral ( n = 20) or unilateral ( n = 20) THA were evaluated for pelvic kinematics during standing and walking tasks using an optoelectronic system. Mean pelvic orientation was assessed during standing, whereas the Gait Variable Score (GVS), maximum and minimum peaks, range and values of pelvic tilt, obliquity and rotation during Heel-Strike and Toe-Off phases of gait cycle were calculated during walking. Data were collected the day before and at seven days after surgery. Results: At baseline, no between-group differences were found. At 7 days, GVS for pelvic tilt ( p = 0.029) and rotation ( p = 0.046) were closer to normative data in bilateral patients, who also revealed lower maximum peak of anterior tilt ( p = 0.013) and lower range of pelvic tilt during gait ( p = 0.031) with respect to unilateral cases. No between-group differences were found for pelvic orientation during standing at any time-point. Conclusions: Bilateral patients revealed more physiological pelvic kinematics than unilateral cases. These findings underline the advantage of patients undergoing 1-stage bilateral THA and may be helpful in selecting personalised rehabilitative approaches.

EFFECT OF SELF-PACED WALKING ON REDUCING COGNITIVE DEMANDS OF WALKING WHILE TALKING

Although walking is considered an automated process, internal and external factors can alter gait performance. Fear of falling leads to walking with a wider base of support and decreased walking speed, due to a combination of shorter stride lengths and/or stride time. Exacerbation of gait deficits have been reported under high cognitive load situations (HCLS, also known as dual-tasks). Talking on a phone is considered an increased HCLS over talking in-person due to visualization of the individual on the phone. The purpose of the study was to explore the added effects of walking while talking on a phone compared to talking in-person. Fifteen healthy older adult subjects (70.86±4.7yrs) performed three conditions while walking on a self-paced treadmill for ten minutes: (1)walking alone, (2)walking while talking in-person, (3)walking while talking on a phone. Mean stride length(SL), stride time(ST), and step width(SW) were compared using one-way, repeated-measures ANOVAs (p=0.10). Dual-task cost of walking while talking in-person and on a phone was calculated for each gait variable and compared with t-tests. Mean gait variables did not differ between conditions (SL p=0.95, ST p=0.77, SW p=0.57). Dual-task costs were not significantly different between talking conditions (SL p=0.99, ST p=0.54, SW p=0.14). Use of a self-paced treadmill allowed the subjects to perform in their “comfort zone”, however, walking on a set-speed treadmill may force walking speed outside of the comfort zone, pushing one’s “reserve”, and revealing differences. Use of a self-paced treadmill better approximates daily life by providing the opportunity to make adaptations under HCLS.

Evaluation of Gait Variable Change over Time as Transtibial Amputees Adapt to a New Prosthesis Foot

A variety of prescribed accommodation periods have been used in published prosthesis intervention studies that have examined biomechanical outcomes. Few investigators included repeated measurements in their study design, leaving questions as to how measured outcomes change as amputees acclimate to a new prosthesis. This paper is the product of our investigation as to whether measured gait variables were affected by the duration of accommodation period, and to assess the relationship between measured outcomes and the subjective perception of the participants. A sample of transtibial amputees were recruited for this study. Gait data was collected by wearable sensor repeatedly, starting immediately after fitting the interventional foot and extending over a subsequent four days. Participants indicated their perceived accommodation quality on a visual analog scale (VAS). A total of twelve commonly used spatiotemporal gait parameters were analyzed. Friedman tests were used to determine overall differences across time points in both early (one hour) and late (day two through five) accommodation phases, for each gait variable. Statistically significant changes across the early phase were found for variables gait speed χ2(2)=8.000, p=0.018, cadence χ2(2)=7.185, p=0.028, and double support time on the sound side χ2(2)=8.615, p=0.013. Across days two through five, no gait variable significantly changed. VAS scores correlated strongly with step count (r=1.000, p<0.001) and cadence (r=0.857, p=0.014). Longer accommodation periods resulted in less deviations of gait variables for the clinical assessment in the process of prosthetic rehabilitation. Trying out prosthetic interventions for less than one hour has yielded unreliable outcomes.