BASIC PRINCIPLES OF WALKING:A COMPARISON BETWEEN THE RECIPROCATING GAIT ORTHOSIS (RGO) AND THE HIP-KNEE-ANKLE-FOOT ORTHOSIS (HKAFO)

Susan Sienko Thomas, M.A. 1, CathleenE. Buckon,OTR/L, MS. I, Renee P. Freeling, B.A. 1, Dora Rex, MSPT 2, Henry Sirolli, RPFT 3, Michael D. Aiona, M.D. Mark Magnusson, Ph.D., M.D. 3, 1. Shriner's Hospital for Crippled Children, 3101 S.W. Sam Jackson Park Road, Portland, OR, 97201, 2, Children's Seashore House, 3405 Civic Center Blvd., Philadelphia, PA, 19104, 3. Children's Hospital of Philadelphia, 34th and Civic Center Blvd., Philadelphia, PA 19104


Introduction

Over the past twenty-five years, the promotion of ambulation in children with mid to high level myelomeningocele and the method to achieve "functional" ambulation has been met with significant controversy. It is often thought that children who require significant orthotic management to achieve ambulation should opt for a wheelchair as their primary mode of locomotion. In order to determine whether children with myelomeningocele were able to achieve "functional" ambulation, Rowley and Rose proposed four basic principles of walking. They include: 1) low energy ambulation at a reasonable speed (25-50% of normal) 2) independent transfer 3) independent "doff and don" of orthotic device and 4) ability to master a step of 15 cm and to walk up and down a ramp. Utilizing the four basic principles of walking, a comparison was made between children with mid to high level myelomeningocele walking with either a reciprocating gait orthosis (RGO) or hip-knee-ankle-foot orthoses (HKAFO's).

Methods and Population

Fifteen children, 7 females and 8 males, mean age 8+1 years (range 3+ 9 to 15), walking with RGOs and crutches were compared with ten children, 3 females and 7 males, mean age 8+6 years (range 5+4 to 12+5) walking with HKAFOs and either crutches or walker. Oxygen consumption was measured using a SensorMedics 2900 metabolic cart using the dilution mode. Oxygen consumption was measured in three phases: resting (measured in a reclined position), walking (performed at a self-selected velocity, and sitting (on a backless stool). To advance to the next phase the subject maintained 3-5 minutes of steady state which is defined as 10% variance in V02, VE and R. Velocity was measured in meters/sec, energy cost was measured in ml/kg/meter, and energy consumption was measured in ml/kg/min. All variables were calculated each minute and the mean for the five minutes of steady state was used for statistical comparison. Select questions from the Pediatric Evaluation of Disability Inventory (PEDI) were used to determine transfer independence to/from a chair and the ability of the child to master a 15 cm step and ramp. A separate form addressing bracing issues was used to determine whether the child was independent in donning and doffing their orthotic device.

Results

A total of eleven children met all of the criteria for functional ambulation, three children from the RGO group and eight in the HKAFO group (Table 1.). All children in both groups could transfer independently. Only one child in the HKAFO group could not don/doff their brace independently. 46% of RGO users and 70% of HKAFO users could master a step. One child from the RGGO group could not master a ramp. Although the ability to master a step shows differences between the groups, the major discriminating factor between the two groups was age matched velocity. Only five of the fifteen children using RGOs walked at a velocity which was at least 25% of the age matched normal, while nine of the ten children using HKAFOs were able to meet the velocity criteria. In addition, the mean energy cost for the fifteen children who walked with RGOs is 8.1 ml/kg/m with a standard deviation of >25, while children using HKAFOs had a mean energy cost of .614 ml/kg/m with a standard deviation of .32. However, both groups have an energy cost which is significantly greater (p<.05 ) than normal (.202 ml/kg/m with a standard deviation of .037).

Discussion

The major difference between the two groups was found in the area of velocity, as the children wearing RGOs walked at a velocity which was much slower than children walking in HKAFOs. The decrease in velocity of children wearing RGOs may be due to the mechanical restriction of the brace, the type of gait pattern used, or the inefficiency of the child in the RGO. All of the children in the HKAFO group were community ambulators according to Hoffer, 1973, while the children in the RGO group were either community or exercise ambulators. The ability to master a step is important for functional community ambulation. In both groups the ability to master a step appeared to be dependent upon the age of the child, as all children under the age of seven regardless of sex or type of orthotic used, were unable to perform this task. The results of this comparison indicate the children wearing HKAFOs master a greater percentage of the criteria for determination of "functional" ambulation than children RGOs. Further study is needed to determine if the differences found in these two groups in this study are due to the type of orthotic device worn or the skill of the child in using the orthotic device. Despite the differences seen in "functional ambulation" between the two groups , all parents were happy with the orthotic devices prescribed to their child. Therefore, the prescription of an orthotic device for walking should take into consideration the criteria for "functional" ambulation; however, it should meet with the needs of the child and family.

References:
Hoffer, M., Felwell, E., Perry, J., Bonnett, C, "Functional Ambulation in Patients with Myelomeningocele", Journal of Bone and Joint Surgery, 55A, 1973:137-153Rowley, D.I., Rose, G., Walking Aids, in Current Concepts in Spina Bifida and Hydrocephalus, eds. CM. Bannister and B.Tew, Mac Keith Press, 1991:104-118