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Background

Ankle osteoarthritis (A-OA)

Over 50,000 new diagnosed cases each year
Has been associated with severe pain and disability
Most commonly presented through post-traumatic injury
Significantly impacts gait mechanics [1, 2]
Can result in a side-to-side difference in gait mechanics [3].

Asymmetry

Valuable in indicating health, outcomes, and risk to the contralateral limb [3]
Studies have reported an asymmetry of <10% in various gait parameters in healthy adults [4]
Asymmetry severity in A-OA patients has not been reported previously

Purpose & Hypothese

Purpose & Hypotheses

Purpose:

The purpose of this study was to determine the degree of gait symmetry in discrete joint kinematic and kinetics in A-OA patients and to determine if symmetry in A-OA patients is significantly different from age & gender-matched healthy cohort

Hypotheses:

We hypothesis that A-OA patients will demonstrate decreased symmetry in gait mechanics when compared to healthy participants.

Methods

Participants

74 total participants
37 unilateral A-OA patients from a previously collected prospective database [5]
- Age 60.16 + 10.4 years, BMI 25.41 + 3.5, 9 males, 28 females
37 healthy participants
- Age, gender, and BMI matched to A-OA participants
- Age 59.92 + 11.7 years, BMI 24.69 + 3.3, 9 males, 28 females.
All participants signed IRB approved informed consent documents before completion of the study

Design

Each participant completed four - seven walking trials at a self-selected pace
Motion capture data and walking speed was collected
- A-OA participant: Eight-camera motion capture system (Motion Analysis Corporation, Santa Rosa, CA; 120 Hz)
- Healthy participants: Ten-camera motion capture system (Qualisys, Sweden; 120 Hz).
- Modified Helen-Hayes marker set

Ground reaction forces (GRF) were captured with four AMTI force plates (AMTI, Watertown, MA, 1200 Hz).
Average walking speed and seven symmetry variables were compared between the A-OA group and the healthy participants
- Knee flexion
- Hip extension
- Ankle plantarflexion (PF)
- Knee range of motion (ROM)
- Hip ROM
- Weight acceptance (early-stage GRF)
- Propulsion (late-stage GRF)
Normalized Symmetry Index (NSI) was used to quantify symmetry in the A-OA and healthy participants [3].

NSI ranges between -100% to 100% where 0% indicates full symmetry [3].
If NS is larger then S then the NSI is positive and if S is larger then NS the NSI is negative
Non-surgical (NS)and which to the surgical (S): A-OA patients (unaffected/affected) and healthy participants (dominant/non-dominant)

Statistics

Paired sample t-test were used to assess differences between the A-OA and control group for BMI, age and walking speed
Due to a significant difference in walking speed (p<0.001) between groups an Analysis of covariance (ANCOVA) with an alpha level of 0.05 was used to determine differences between the groups for each of the variables of interest while covarying for walking speed.

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Results

Table 2: NSI measures in A-OA and healthy controls. (Mean SD), P-value was calculated with a covariant for walking speed (m/s)

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Discussion

Discussion & Significance

Similar to previous studies, A-OA significantly impacts gait mechanics
A-OA decrease in gait symmetry compared to healthy participants
A-OA resulted in a decrease in hip extension symmetry
- Participants used greater hip extension to most likely compensate for limitations in ankle motion [4]
Large SD in ankle motion present in the current study could impact study results and indicates the need for a larger sample to account for this increase in variability between participants
Knowing that hip extension symmetry is effected by A-OA, targeted therapies can be developed to treat patients with A-OA and prevent further injury

Future Studies

Should assess the restoration of symmetry following surgical intervention
Focuses on developing targeted rehabilitation programs to improve symmetry
Assess the impact of decreased movement and load symmetry on OA progression in other lower extremity joints on both the ipsilateral and contralateral limb.

Limitations

Data was collected at two different locations
Differences in marker placement between testing sites could have impacted the study outcomes

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Acknowledgments

A-OA data was initially collected at Duke University under the direction of the senior author and the same data collection methods were used at Virginia Tech for the collection of the healthy control participants. We would like to acknowledge Laura Dickerson for her help with the collection of the healthy participant data.

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References

[1] C.N. Hughes-Oliver et al. Gait & Posture 65 (2018) 228–233

https://doi.org/10.1016/j.gaitpost.2018.07.180

[2] Glazebrook, Mark et al. 1 March 2008 The Journal of Bone and Joint Surgery

doi: 10.2106/JBJS.F.01299

[3] R. Queen et al. 23 January 2020 Journal of Biomechanics

https://doi.org/10.1016/j.jbiomech.2019.109531

[4] D. Schmitt et al. Spetember 2015 Gait & Posture Vol. 42

https://doi.org/10.1016/j.gaitpost.2015.07.005

[5] R. Queen et al. October 2017 Clin. Orthop., Vol. 475

doi: 10.1007/s11999-017-5405-7.

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Ankle Osteoarthritis Causes Hip Extension Asymmetry Compared to Healthy Controls