Observational Gait Scale
I. Descriptive Information:
Title: Observational Gait Scale (OGS)
Edition: The OGS is a modified version of the Physician’s Rating Scale (Koman et al., 1994). The Physician’s Rating Scale (PRS) was created to examine the gait of young children with cerebral palsy in the sagittal plane after intramuscular injections of botulinum toxin type-A (BTX-A) for equinus gait. This scale did not appear to be sensitive or reliable in detecting specific changes after treatment with BTX-A (Corry et al., 1998). To improve the sensitivity of this scale, alterations were made and it was turned into the OGS (Boyd and Graham, 1999). Alterations to the PRS included the removal of three of the original sections (Equinus foot, Hind foot, Speed of gait) along with adding a section on “Change” (which aimed to improve discrimination between the two treatment groups in the Corey et al. study).
Dates of Publication and Revision: Published in 1999
Author (s): Roslyn N. Boyd and H. Kerr Graham created the OGS in 1999 (Mackey et al. examined reliability/validity of OGS in 2003).
Source (publisher or distributor, address): Source of test could not be found. The address of where the study by Boyd and Graham was conducted: (Hugh Williamson Gait Laboratory, Royal Children’s Hospital, Flemington Road, Parkville, Melbourne, Victoria 3052, Australia). A copy of the OGS form can be found here: http://onlinelibrary.wiley.com/doi/10.1111/j.1468-1331.1999.tb00031.x/epdf
Costs (booklets, form, kit): Cost of OGS form is not listed online. Form can be viewed from the above source. The only major costs would potentially be if video analysis equipment for video recording or software was utilized for OGS scoring like in the Boyd and Graham, Mackey et al., and Pool et al. studies. In the powerpoint presentation by Julie Bouck, analyzing gait via video software is not mentioned so this could potentially be completed in the clinic in the presence of the patient.
Purpose: The main purpose of the OGS is to rate gait parameters from video recordings utilizing a structured scale. The OGS seeks to evaluate or measure the amount of change in an individuals gait pattern over time. The OGS was created as a simple low-technology tool to aid in the biomechanical assessment in the clinical setting specifically the knee joint during mid-stance (crouch and recurvatum). Boyd et al., cite that this test may be useful when children are too small or are insufficiently cooperative for instrumented gait analysis. Furthermore, they had found this scale to be very useful when analyzing a typical walk viewed on split-screen video in slow motion.
Type of Test (eg, screening, evaluative; interview, observation, checklist or inventory): The OGS is an evaluative/observational test that incorporates qualitative notions of gait. When analyzing gait, the examiner has to check the correct boxes in each section of the OGS.
Target Population and Ages: Target age range is from 6-21 in children and young adults with cerebral palsy. The National Guideline Clearinghouse recommends the OGS for those that demonstrate idiopathic toe walking through gait assessment.
Time Requirements – Administration and Scoring: None of the sources referenced at the bottom cite the exact length of time to complete the OGS. Mackey et al. cite that “This version of the PRS has more complexity and is more time consuming.” No specific time frames were given online.
II. Test Administration
Administration: Child either ambulates in front of camera or clinician while demonstrating most typical/natural gait pattern. An experienced clinician then scores the OGS while analyzing the gait pattern from both frontal and lateral views by checking off the correct boxes that correspond with the demonstrated gait deviation in each section of the OGS form. If the patient is videotaped then the clinician will watch video recordings to score the OGS. Again, the most critical notion to this test is to make sure the child is ambulating with their most typical gait pattern.
Scoring: The OGS is a scale with 8 sections (1: Knee position in midstance, 2: Initial foot contact, 3: Foot contact at midstance, 4: Timing of heel rise, 5: Hindfoot at midstance, 6: Base of support, 7: Gait assistive devices, and 8: Change) where you score both the left and right lower extremities by selecting the appropriate numerical value. Specifically, the knee position in midstance section has two subsections where you have to select the appropriate numerical value in either the Crouch or Recurvatum subsections (Neutral is under crouch). A perfect score would be a 22 on each limb. Even though this was not specifically stated, it seems that the higher the score, the less impairments demonstrated by the child.
Type of information, resulting from testing (e.g. standard scores, percentile ranks): The OGS gives a standard score out of 22. The eight sections of the OGS portray specific information pertaining to gait including: knee position at midstance as either a crouch or recurvatum; initial contact of the foot with either being on the forefoot, foot-flat, or heel; foot contact description at midstance; the amount and timing of heel rise; description of hindfoot at midstance as either varus, valgus, or neutral; the amount of base of support; assistive devices utilized; and change with either being worse, better, or neutral. Overall, several items in this test are geared to quantify visually the relationship between the ankle and knee position during stance. With utilizing the OGS, Boyd et al. looked to distinguish true equinus (plantarflexion/knee extension coupled in midstance) from apparent equinus (hamstring spasticity is greater than calf spasticity).
Environment for Testing: Clinic setting or gait analysis laboratory for adequate video recordings. As mentioned above, Boyd et al. and Mackey et al. analyzed gait of individuals with cerebral palsy via video recordings. In the powerpoint by Julie Bouck on Pediatric Gait Assessment, she does not specify whether the OGS has to be completed by analyzing video recordings or examining a patient in the clinic.
Equipment and Materials Needed: Adequate amount of space to allow the patient to ambulate on a flat floor surface. Potentially a camera for videotaping and lab for child to ambulate in while videotaping.
Examiner Qualifications: Experienced clinicians are required to complete this test. Mackey et al. utilized a pediatric PT and an orthopedic pediatric surgeon to examine intra-rater and inter-rater reliability and validity of the OGS. Both observers worked in a tertiary-level pediatric hospital and had 5 years experience with observing gait and reviewing gait analyses in children with cerebral palsy. Also, both of these observers had up to 2 years experience utilizing the OGS in the clinical setting.
Psychometric Characteristics: This test has been found to be valid and reliable. MCIDs and responsiveness to change values have not been established for this test at this time.
Standardization/normative data: Normative values have not been established for this test at this time.
Evidence of Reliability: In Rathinam et al., the OGS was reported to have very good inter-rater reliability, however only the sagittal plane (ankle/foot and knee joints) items scored maximum agreement. Mackey et al. found the OGS had acceptable inter-rater and intra-rater reliability for knee and foot position in midstance, initial foot contact, and heel rise. There were also lower intra-rater reliabilities found for section 5 (hindfoot position) and section 6 (base of support). Overall, data from this study suggests that the first four sections of the OGS scale have an acceptable level of reliability and validity when assessing gait in children with spastic diplegia and problems principally in the sagittal plane.
Evidence of Validity: Mackey et al cited that, “Correlation of 3-dimensional gait analysis data with OGS scores for the first four sections showed high validity for our most reliable observer.” This comparison with 3-dimensional gait analysis suggests that the sections of knee and foot position in mid-stance, initial foot contact, and heel rise have high validity.
Discriminative: This test does not have the discriminative ability to differentiate between young or older aged children with cerebral palsy. The only discriminative quality in the current research is that it can help distinguish between a true equinus and apparent equinus.
Predictive: This test is not a predictive measure in that it does not have the ability to predict changes in motor function related to gait with age progression in children with cerebral palsy.
III. Summary Comments
Strengths: The OGS has high reliability and validity. It includes specific measuring properties that are geared toward the impairments of children with cerebral palsy. It requires no written qualitative gait analysis therefore increasing efficiency on part of the clinician. It looks at change over time in both lower extremities.
Weaknesses: The OGS is somewhat complex with requiring a good amount of experience whether it be to set the video recording up with the specific markers on the joints of interest (if computer software or video recordings are utilized) as well as to make accurate assessments. There are also no normative, MCID, or responsiveness to change values and it doesn’t have any predictive qualities. It has only been validated for children with cerebral palsy. Pool et al. cite that the OGS has poor sensitivity. This test is also not listed on rehabmeasnures.org limiting its accessibility to the public. Mackey et al., cite that “it takes a long time to complete this test and videos of young children are often more difficult to record and standardize due to younger children’s lack of compliance.”
Clinical Applications: A PT with enough experience in pediatrics can perform this in the clinic and have reasonable validity to look for change over time. This test could also help guide the examination for a novice PT in pediatrics in terms of making sure to document on specific aspects of gait for patients with cerebral palsy like knee position at midstance.
IV. Summary of research article utilizing OGS:
Pool D, Blackmore AM, Bear N, et al. Effects of short-term daily community walk aide use on children with unilateral spastic cerebral palsy. Pediatr Phys Ther. 2014 Fall;26(3):308-17. doi: 10.1097/PEP.0000000000000057.
The main purpose of this article was to look at how the Walk Aide, a form of functional electrical stimulation (FES), effects impairments affecting gait in children with unilateral spastic cerebral palsy. The authors hypothesized that 8 weeks of FES would improve ankle dorsiflexion strength, ROM, selective motor control, gastrocnemius spasticity, balance, and gait in this patient population. The intervention protocol included a 20-week, multiple single-subject A-B-A design with a 6-week pre-FES phase, an 8-week FES phase, and a 6-week post-FES phase (children wore their AFOs during the pre-FES phase but not during FES and post-FES phases). Twelve children from the ages of 5 to 16 wore the Walk Aide diurnally for 8 weeks. During the FES phase, children were asked to use the device for at least 1 hour a day for 6 days a week. Measurements were taken on a weekly basis for ankle range of motion, dorsiflexion and plantar flexion strength, selective motor control, gastrocnemius spasticity, single-limb balance, Observational Gait Scale (OGS) score, and self-reported toe drag and falls. When comparing the pre-FES phase to the FES phase, significant improvements were seen for ankle range of motion, selective motor control and strength, along with reductions in toe drag, spasticity, and falls (these improvements were maintained during the post-FES phase). However, no change was noticed for OGS score. The main conclusion was that this study supports the intermittent short-term use of FES to address the main impairments affecting gait in children with unilateral spastic cerebral palsy. This is particularly true for children functioning at GMFCS level I.
How OGS was utilized in this study: Silicon Coach Pro7 was the software program used for video analysis. Each child was video-recorded while walking barefoot at a self-selected speed without the Walk Aide. Videos of walking without the Walk Aide were presented in randomized order to a blinded assessor, who gave each child an OGS score out of 20. The section of “change” in the overall gait pattern was omitted to preserve blinding.
Interpretation of OGS results: “The reductions in toe drag and falls were not reflected in the OGS measures, possibly because of poor OGS sensitivity and the lack of quantitative measurements during gait. Given that a change of the ankle joint of as little as 2° can significantly alter foot clearance, the OGS would not have been able to account for such a small difference and may have underestimated the direct effect of FES on foot clearance for the reduction in toe drag and falls.”
References:
Bouck, J. Pediatric Gait Assessment. [Powerpoint]. UPTA Fall Conference; 2014.
Boyd R, Graham HK. (1999) Objective measurement of clinical findings in the use of botulinum toxin type A for the management of children with cerebral palsy. Eur J Neurol 6 (Supp. 14): S23–35.
Corry I, Cosgrove AP, Duffy C, et al. Botulinum toxin A compared with stretching casts in the treatment of spastic equinus: a randomised prospective trial. J Pediatr Orthop. 1998; 18: 304–11.
Koman LA, Mooney J, Smith B, et al. Management of spasticity in cerebral palsy with botulinum-A toxin:report of a preliminary, randomised, double-blind trial. 1994; J Pediatr Orthop. 14: 299–303.
Mackey AH, Lobb GL, Walt SE, et al. Reliability and validity of the Observational Gait Scale in children with spastic diplegia. Dev Med Child Neurol. 2003 Jan; 45(1):4-11.
Pool D, Blackmore AM, Bear N, et al. Effects of short-term daily community walk aide use on children with unilateral spastic cerebral palsy. Pediatr Phys Ther. 2014 Fall;26(3):308-17. doi: 10.1097/PEP.0000000000000057.
Rathinam, C.;Bateman, A,; Peirson,; Skinner, J;: Observational gait assessment tools in paediatrics –A systematic review. Journal of Gait and posture 40,279-285, 2014.
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This outcome measure seems like a great tool to utilize for pediatric physical therapist. I like the idea of video
taping the patient walking so that you can analyze it afterwards. This would save treatment time with the patient so that the clinician can score the sheet later. I also like that you have the video readily available and can re-watch it even in slow motion if necessary, to ensure that you pick up all aspects of the gait cycle. It is also beneficial that you can compare videos before and after intervention to compare. This could be used to visually show the patient their progress instead of just showing them a score. Good job and thanks for a great summary.