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Differences in Measures of Strength and Dynamic Balance among Individuals with Lower-Limb Loss Classified as Functional Level K3 Versus K4

Beisheim, Emma Haldane, PT, DPT1; Horne, John Robert, CPO2; Pohlig, Ryan Todd, PhD3; Sions, Jaclyn Megan, PhD, PT, DPT1

American Journal of Physical Medicine & Rehabilitation: April 3, 2019 - Volume Publish Ahead of Print - Issue - p
doi: 10.1097/PHM.0000000000001183
Research Article: PDF Only

Objective For individuals with lower-limb loss (LLL), functional mobility (i.e. K-level) classification can be subjective. Performance-based outcome measures (OM) improve the objectivity of K-level assignment; therefore, this study aimed to determine differences in functional strength- and dynamic balance-based OM performance between K3- and K4-classified adults with LLL.

Design: Prosthetists used subjective information and prosthetic componentry to determine K-levels prior to OM testing for adults with a unilateral transtibial (n=50) or transfemoral amputation (n=17). OM [i.e., 5-Times Sit-to-Stand Test (5xSTS), Figure-of-8 Walk Test (F8WT), 360° Turn Test (360TT), and modified Four-Square Step Test (mFSST)] were administered by a blinded examiner. Univariate analyses of variance (ANOVAs) were used to evaluate between-subgroup differences.

Results K4-classified participants with a unilateral transfemoral amputation performed better on all OM when compared to K3-classified peers, while K4-classified individuals with a transtibial amputation performed better on the mFSST compared to K3-classified peers (p<.050).

Conclusion K4-classified individuals demonstrated greater lower-extremity functional strength and better dynamic balance compared to K3-classified peers. To assist with K-level classification, clinicians should consider selecting OM that objectively differentiate between K-levels (i.e., mFSST for those with a unilateral transtibial or transfemoral amputation; 5xSTS, F8WT, and 360TT for those with a transfemoral amputation).

1University of Delaware, Department of Physical Therapy, Delaware Limb Loss Studies, Newark, DE;

2Independence Prosthetics-Orthotics, Inc., Newark, DE;

3University of Delaware, Biostatistics Core Facility

Correspondence:Name: J. Megan Sions, Address: 540 S. College Avenue, Suite 210JJ, Newark, DE 19713, Business telephone number: (302) 831-7231, Email address:


Competing Interests: Dr. Sions is a consultant for Independence Prosthetics-Orthotics, Inc.

Funding: National Institute of Health, grant numbers RO3HD088668 and 5T32HD007490-17.

Financial Benefits to Authors: None to report.

Presentation: This work has been accepted for presentation as a platform presentation at the American Academy of Orthotists and Prosthetists (AAOP) Annual Meeting (March 6-9, 2019; Orlando, FL).

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