Identifying kids' range of motion

Dec 12, 2008

Current safety equipment and medical procedures for children are based on adult measurements and benchmarks. Two Kettering faculty have established child-sized measurements to improve everything from car seats to chiropractic care.

Anyone over 30 who has watched kids tumble around the living room floor knows that children are more flexible than adults. However, until recently, measurements for car safety restraints, physical therapy and various consumer products were based on the cervical spine range of motion reference values for adults.

Subsequently, there is a large body of data related to adult flexibility and range of motion, but virtually none for children 10 and under. Enter Dr. Janet Brelin-Fornariand Dr. Terri Lynch-Caris, of Kettering University. They, in collaboration with Dr. Karl D. Majeske, of Oakland University, and Dr. Shrishail Nashi, of Michigan State University’s College of Medicine, have established reference values for cervical spine range of motion in pre-pubescent children.

The study is a collaboration between Kettering University Mechanical and Industrial Engineering departments and McLaren Regional Medical Center in Flint.

What this means is that products ranging from seat belts to helmets to services like rehabilitative physical therapy for children will be more appropriate for their body’s flexibility, based on the findings of their field research.

“If we use the values given by the American Medical Association (AMA) we know that they do not correctly reflect children’s range of motion,” said Lynch-Caris, associate professor of Industrial and Manufacturing Engineering. Range of Motion (ROM) of the human head involves flexion, extension, lateral bending (side to side) and axial rotation (turning right and left).

“Most previous research takes adult measurements and extrapolates them backward to children’s sizes, assuming that they will be representative of children’s range of motion. There is a small data set of actual data gathered on children,” Lynch-Caris added.

“We saw a larger range in the children we tested versus the average given in the AMA guidelines,” said Brelin-Fornari, “and we actually saw a lot of variability within the child population we worked with.” AMA guidelines don’t include variability, even for adult populations, according to Brelin-Fornari, associate professor of Mechanical Engineering and Crash Safety Center director.

“Range of motion in children is different than that of adults,” said Lynch-Caris, “it is no surprise our data proved what people already knew. That children are more flexible,” added Brelin-Fornari.

The Kettering study, begun in 2005, utilized the cervical range of motion device, referenced with respect to the Frankfort Plane, to measure the active cervical spine range of motion in all three cardinal planes of the human body, for 106 subjects whose ages ranged from 8 to 10 years. The active range of motion for flexion, extension, lateral extension, and rotation was calculated. Children measured for the study were third and fourth grade students at Hill Elementary in Davison, Mich., and Tomek East Elementary in Fenton, Mich.

Testing consisted of several non-invasive measurements using a Cervical Range of Motion (CROM) device to evaluate the flexion, extension, lateral extension, and rotation of the cervical spine of each subject. Subjects were also measured for standing height, seated height, shoulder height, head and neck circumference, and weight.

The CROM device is a goniometric device (to measure angles) using fluid-damped inclinometers (to show relationship to the horizontal plane) and magnets for fast, accurate readings without much oscillation. Made of a lightweight frame, it attaches to a subject's head with Velcro straps. Three inclinometers measure rotation about the different planes of cervical motion and data is recorded by investigators.

The observed data significantly differed from the published AMA guidelines for adults, but fell within the range of the reference value for 10 year olds.

“Previously there was only one value for kids at age 11 that had been included in a study,” said Lynch-Caris, “that value fell within the range of our study. With this study  we were able to establish reference values that never existed before. Now we have real data that can be used to develop real-life models like crash dummies,” she said.

Motivation for the Kettering-based study was directly related to testing done in the Crash Safety Center on child vehicle safety restraints (child car seats). Currently, one of the issues facing researchers is the six year old crash test dummy whose neck does not dynamically represent a six year old living child. Data from the study will help support development of a more accurate six year old dummy,” said Brelin-Fornari.

The study data will also help in the development of toy-related products such as bike helmets, chiropractors might be able to use the data for patients, as well as physical therapists working with children after injury or surgery. “This data will help medical professionals know when the therapy has helped the child reach a “normal” range of motion for a child that age,” said Brelin-Fornari.

“The most important thing is that this is a starting ground, the numbers have never been out there before and now we have them and can use them,” Brelin-Fornari concluded.

The study has been published in the August 2008 edition of the Journal of Biomechanics published by Elsevier,

For more information about the study, contact Dr, Janet Brelin-Fornariat or Dr. Terri Lynch-Caris at

Written by Dawn Hibbard