ORLANDO, Fla. — Study results presented here showed that children consistently flexed a prosthetic knee joint during crawling, contrary to a conventional approach for rehabilitation in children with limb loss, which typically consists of either no knee, a pylon or a locked knee with full extension.
The study is part of a multicenter pediatric knee project that seeks to “quantify the knee activity of infants and toddlers who need a knee prosthesis,” said Mark Geil, PhD, associate professor in the department of kinesiology and health at Georgia State University. “The conventional approach for rehabilitation for children with limb loss is to give them either no knee or actually put a knee in the prosthesis and lock it with full extension until they’ve achieved full upright standing and until they start to take some steps with independent standing and walking, and that is 3 or 4, sometimes even 5 years old. The rationale for that has been…that the knees were too large. But that rationale became a clinical motivation about children that it turns out is false.
“The thought is that a 3-year-old can’t do that [flex and extend the knee joint by hip flexors and extensors]. That it requires a sort of neuromotor synergy that they don’t have because they are not at that developmental stage. While that is intuitively sound, it’s never been tested. We assumed they couldn’t do something without finding out if they could do it in the first place.”
Articulated vs. locked knee
Five infants and toddlers with unilateral knee disarticulation or transfemoral level amputations aged 11 months to 36 months and who were crawling, but not walking, were tested within 2 weeks of initial prosthesis fitting. Researchers placed 10 reflective markers on the children’s shoulders, hips, knees and ankles and performed motion analysis, which included crawling with a normal articulated knee function and a locked knee in full extension. Researchers also recorded the children on video performing functional activities such as tall kneel, ascending stairs, playing on a slide and sit-to-crawl and crawl-to-sit. All parents answered satisfaction questionnaires.
Overall study results showed that children consistently flexed the prosthetic knee joint during crawling when one was provided to them. Four of five children showed improvement in contralateral knee motion, compensating less when the knee was able to flex. Researchers also found improvement in frontal hip angle.
Geil noted the children in the study crawled faster with the articulated knee and were less frustrated.
“A developing child needs to explore their environment, they need to get from place to place and when we can help them do that faster, they can do it better. I think the benefits are profound. If [parents] can get an articulated knee in [their child’s] very first prosthesis, it’s wildly important,” Geil said. “The increase of parental satisfaction was apparent in our surveys and may increase compliance. Deviations disappeared when the knee was allowed to articulate more, but the ultimate question is at what age is it most beneficial to incorporate the knee unit. We think in this protocol it is in the very first prosthesis.” — by Casey Tingle
Disclosure: Geil has no relevant financial disclosures.