Differences in Measures of Strength and Dynamic Balance Among Individuals With Lower-Limb Loss Classified as Functional Level K3 Versus K4.
Emma Haldane Beisheim, John Robert Horne, Ryan Todd Pohlig and 1 others
PMID 30950838WHAT IT FOUND
K4 adults with transfemoral loss were faster than K3 on strength, complex walking, and balance tests.
For transtibial loss, only the Four Square Step Test differed. Turning toward prosthesis did not differ from turning toward sound limb.
Key findings
01K4 participants with a transfemoral amputation were significantly faster than K3 participants on all tested strength and balance measures; K4 participants with a transtibial amputation were significantly faster on the modified step test.
02Within participants, turn times toward the prosthetic side did not differ significantly from turn times toward the sound side for either amputation level or K-level subgroup.
03K3 transtibial participants were older and more likely to have dysvascular amputation than K4 participants; K3 transfemoral participants had higher mean BMI than K4 participants.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
K-level assignment was subjective and based on prosthetist interview and observation of componentry, not on the timed tests. The study compared people already classified as K3 or K4; it did not assign treatment and cannot show that these tests cause a K-level or that therapy changes K-level. Participants were only longer-term unilateral transtibial or transfemoral prosthesis users, so results may not apply to acute amputation, bilateral amputation, or lower-level ambulators. Age, body mass index, and amputation cause differed between some K3 and K4 groups and were not adjusted for, so test differences may reflect those factors. The paper reports preliminary group differences and confidence intervals, not validated diagnostic cut-offs or treatment effects.
Declared interests
The supplied metadata lists NIH extramural research support. The article text does not provide a separate conflict-of-interest declaration. Prosthetists from Independence Prosthetics and Orthotics, Inc. assigned K-levels.
The easy way to misread this
Do not read these test times as proven cut-offs or as proof that therapy can move someone from K3 to K4. K-levels were assigned subjectively, age and other factors were not adjusted for, and the study only compared existing groups.