Toward evidence-informed AFO prescription: Identifying factors that guide

clinician decision-making

Kyra KaneBScPT, MSc, PhD candidate

University of Saskatchewan

Senior Physical Therapist, Children’s Program

Regina Qu’Appelle Health Region

Outline

• We are conducting 2 studies to improve our understanding of:

1. Clinician experiences with AFO prescription

Prescription evolves as part of a collaborative process

Challenges and strengths of the current process

2. How the angle of the ankle in the AFO affects walking in children with CP

• AFO prescription decisions are based on limited evidence

Cerebral palsy

• Injury to the developing brain

• Impaired movement and posture

• Varied impairments (e.g., spasticity, weakness, contracture, deformity) and gait patterns

• ~50% wear AFOs (Wingstrand, 2014)

Ankle-foot orthoses (AFOs)

• Apply forces to prevent unwanted movement• Control motion, compensate for weakness

or abnormal distal motor control

• Control position of ground reaction force relative to lower extremity joints•By altering moments, AFOs affect muscle

activity and movement (e.g., Butler & Nene, 1991; Owen, 2005; Meadows et al., 2008)

Not all AFO prescriptions are created equal

• AFOs can improve gait quality (Bowers & Ross, 2009; Figueiredo et al., 2008; Morris, 2002a; Owen, 2010)

• Effect may not be optimal

• Current AFO maximized gait quality only 37% of the time (Ries et al., 2014)

• Reasons behind this are not understood• Matching AFO design to child’s impairments/

gait pattern is important (Davids, 2007)

• Lack of evidence to guide clinical decisions (Morris, 2002b; Ries et al., 2014, 2015)

AFO prescriptionClinician experiences and considerations

Purpose

• To explore clinician perspectives & experiences with AFO prescription for children with CP • Learn about factors that influence AFO prescription for children with

CP in Canada

• Gain insight into potential ways to improve the process and outcomes for children who wear AFOs

Methods

• Focus groups conducted at 5 rehabilitation facilities in 4 provinces

• 32 clinicians who work with children who have CP• 4 MDs, 10 orthotists, 17 PTs,

1 kinesiologist

Semi-structured interviews

•Purpose and types of AFOs•Process to obtain AFO•Roles of team members •Clinical evaluation • Facility processes:

• What works well?• What could be changed?• Ideal process?

Analysis - Interpretive Description

• An approach to qualitative inquiry into health-related experiences (Thorne et al., 1997, 2004)

• Captures themes & patterns within subjective perceptions

• Goes beyond description, to explore meanings & explanationsof experiences

• Generates an interpretive description that can inform clinical knowledge

• 3 researchers participated in coding to establish categories and themes

Results

• Categories: • Processes to obtain and monitor AFO

• Information that affects choice of AFO design

• Factors that challenge or strengthen treatment outcomes

• Theme: • Prescription as a collaborative, iterative, and individualized process

Simplified process to obtain & monitor AFO

Physical Therapy

follow-up

Orthotist follow-up (fit issues)

Prescriber writes

requisitionWaitlist

Ongoing evaluation, communication, adjustments to AFO (orthotist & PT, sometimes MD)

Revisit prescription if a team member decides goals are not being met

Orthotist casts for

AFO

Orthotist fits AFO

Factors that challenge or strengthen outcomes

System issues

Team

Equipment

Parent/child

• Waitlist

• Staffing budget

• Proximity to other team members

•Competing priorities• 1 design may not

achieve all goals

• Compliance, acceptance of AFO

Potential significance

• A comprehensive understanding of the factors influencing the process may benefit clinical practice• Identifying these factors may be a first step toward the development

of guidelines to help clinicians improve AFO prescription for children with CP

Angle of the ankle in the AFO (AA-AFO)

Effect on walking mechanics in children with CP

Does the AA-AFO impact walking?

• AFOs are typically fabricated with the ankle at 90°

• Erroneous belief that at midstance the shank is vertical and the ankle is 90°

•Unfounded assumption that this position is necessary to maintain ankle plantarflexormuscle flexibility

•This practice may be problematic for children with tight/stiff gastrocnemius (GN) muscles (e.g., CP)

(Owen, 2010, 2014; Meadows et al., 2008; Morris et al., 2011; Nuzzo, 1983, 1986)

Consequences of inappropriate AA-AFO

• Bracing the ankle in a position that demands too much length from GN may cause• Foot damage (midfoot break, skin lesions) • Knee flexion during gait• Contractures

(Mau

rer et al., 20

13

)

(Owen, 2014; Karas, 2002)

Positioning the ankle in plantarflexion will cause loss

of muscle length… Myth?

• Accommodate GN tone/stiffness to treat it (Owen, 2010)

• Positioning the ankle in plantarflexion may allow the GN to function more effectively and may increase muscle length

• Fears may not be warranted• AFOs have not been proven to prevent deformity or

contractures (Morris et al., 2011)

• GN contracture may be easier to correct than a rocker bottom foot or knee flexion contracture

Save the

foot!

Purpose and hypothesis

• Purpose: Examine effects of individualized AA-AFO

• AA-AFO based on clinical measures of calf muscle state (as described by Owen,

2005, 2010) will result in more normal • Joint motion

• Muscle excursion

• Muscle activation

• Functional performance

AA-AFO

Determining the AA-AFO

1.Available muscle length?

2.How stiff is the muscle?

3.Any bony alignment issues?

4.Risk of losing muscle length?

Owen (2005, 2010)

Determining the AA-AFO

Methodology

• Participants: children with CP, GN tightness, wear AFOs

• Compare 3 walking conditions: 1. Shoes only

2. Child’s usual AFO (tuned)

3. Solid AFO with individualized AA-AFO (tuned)

• Biomechanical measures:• 3D gait analysis

• Surface EMG

• Computerized muscle length modelling

• Functional measures• Pediatric Balance Scale

• 10-meter walk test

Shoes Solid AFO with individualized AA (20° PF)

Usual AFO (Hinged AFO)

24°

12°22°

Results: Shank to vertical angle (right leg)

Right knee flexion/extension

0

10

20

30

40

50

60

70

80

90

Stance Swing

Shoes

Usual AFO

Solid AFO (20° AA)

Phase of Gait Cycle

Exte

nsi

on

Flex

ion

Deg

rees

Right ankle dorsiflexion/plantarflexion

-30

-25

-20

-15

-10

-5

0

5

10

15

Phase of Gait Cycle

Pla

nta

rfle

xio

nD

ors

ifex

ion

Deg

rees

Stance Swing

Shoes

Usual AFO

Solid AFO (20° AA)

Potential significance

• Inform best practice by indicating how the AA-AFO can affect mobility

• Reduce costly trial-and-error decision-making in the AFO prescription process

• Improve mobility outcomes for children

Take away points

• Limited understanding of how AFOs are prescribed

• Successful AFO prescription requires teamwork –• Child, family, orthotist, PT, MD at all stages (assessment, goal

setting, prescription, fitting, tuning, follow-up…)

• Allows the prescription to evolve

• One research priority is to understand the effects of aspects of the prescription such as the AA-AFO

Thank you to the children and clinicians who have participated!

Advisors, collaborators, & consultant:Kristin Musselman, PT, PhDJoel Lanovaz, PhDPatricia Manns, PT, PhDElaine Owen, MBE, MSc, SRP, MCSP

Acknowledgements

References and further reading• Butler, P. B., & Nene, A. V. (1991). The biomechanics of fixed ankle foot orthoses and their potential in the management of cerebral palsied

children. Physiotherapy, 77, 81-88.• Davids, et al. (2007). Indications for orthoses to improve gait in children with cerebral palsy. J Am Acad Orthop Surg. 15, 178-188.• Figueiredo et al. (2008). Efficacy of ankle-foot orthoses on gait of children with cerebral palsy: systematic review of literature. Ped Phys Ther

20(3), 207-223.• Jagadamma et al. (2010). The effects of tuning an AFO-Footwear Combination on kinematics and kinetics of the knee joint of an adult with

hemiplegia. Prosthet Orthot Int. 34(3): 270–276.• Meadows, B. (2014). Tuning of rigid ankle-foot orthoses is essential. Prosthet Orthot int, 38(1), 83-83.• Meadows C, Bowers R, Owen E. (2008). Biomechanics of the hip knee and ankle. In: Hsu J, Michael J, Fisk JR editors. Atlas of orthoses and

assistive devices. 4th ed. Philadelphia: American Academy of Orthopedic Surgeons.• Morris, C. (2002a). A review of the efficacy of lower‐limb orthoses used for cerebral palsy. Dev Med Child Neurol, 44, 205-211.• Morris, C. (2002b). Variations in the orthotic management of cerebral palsy. Child: care, health and development, 28, 139-147.• Nuzzo RM. (1983). High-performance activity with below-knee cast treatment, part I: mechanics and demonstration. Orthopedics, 6: 713-23. • Owen, E. (2014). Pediatric gait analysis and orthotic management with AFO footwear combinations: A segmental kinematic approach to

rehabilitation; Course notes. • Owen, E. (2010). The importance of being earnest about shank and thigh kinematics especially when using ankle-foot orthoses. Prosthet

Orthot Int, 34(3), 254-269. • Owen, E. (2005). Proposed clinical algorithm for deciding the sagittal angle of the ankle in an ankle-foot orthosis footwear combination. Gait

Posture 22S: 38-39.• Owen, E. (2004.) “Tuning of ankle-foot orthosis combinations for children with cerebral palsy, spina bifida, and other conditions.”

Proceedings of European Society of Movement Analysis in Adults and Children Seminars.• Ries AJ, Novacheck TF, Schwartz MH. The efficacy of ankle-foot orthoses on Improving the gait of children with diplegic cerebral palsy: A

multiple outcome analysis. PM R. 2015;7(9):922-929.• Ries A, Novacheck T, Schwartz M. A data driven model for optimal orthosis selection in children with cerebral palsy. Gait Posture.

2014;40(4):539-544. • Ross, K., & Bowers, R. (2009). A review of the effectiveness of lower limb orthoses used in cerebral palsy.

http://strathprints.strath.ac.uk/15328/

Information that affects AFO design

Factors that challenge or strengthen outcomes