VA RR&D Center for Limb Loss and Mobility (CLiMB), VA Puget Sound Health Care System, Seattle, Washington, United States of America.
Elson S. Floyd College of Medicine, Washington State University, Spokane, Washington, United States of America.
PLoS One. 2022 May 10;17(5):e0268136. doi: 10.1371/journal.pone.0268136. eCollection 2022.
Prosthetic foot stiffness plays a key role in the functional mobility of lower limb prosthesis users. However, limited objective data exists to guide selection of the optimal prosthetic foot stiffness category for a given individual. Clinicians often must rely solely on manufacturer recommendations, which are typically based on the intended user's weight and general activity level. Availability of comparable forefoot and heel stiffness data would allow for a better understanding of differences between different commercial prosthetic feet, and also between feet of different stiffness categories and foot sizes. Therefore, this study compared forefoot and heel linear stiffness properties across manufacturer-designated stiffness categories and foot sizes. Mechanical testing was completed for five types of commercial prosthetic feet across a range of stiffness categories and three foot-sizes. Data were collected for 56 prosthetic feet, in total. Testing at two discrete angles was conducted to isolate loading of the heel and forefoot components, respectively. Each prosthetic foot was loaded for six cycles while force and displacement data were collected. Forefoot and heel measured stiffness were both significantly associated with stiffness category (p = .001). There was no evidence that the relationships between stiffness category and measured stiffness differed by foot size (stiffness category by size interaction p = .80). However, there were inconsistencies between the expected and measured stiffness changes across stiffness categories (i.e., magnitude of stiffness changes varied substantially between consecutive stiffness categories of the same feet). While statistical results support that, on average, measured stiffness is positively correlated with stiffness category, force-displacement data suggest substantial variation in measured stiffness across consecutive categories. Published objective mechanical property data for commercial prosthetic feet would likely therefore be helpful to clinicians during prescription.
假肢脚的刚度在下肢假肢使用者的功能性移动能力中起着关键作用。然而，目前用于指导为特定个体选择最佳假肢脚刚度类别的客观数据有限。临床医生通常只能依赖制造商的建议，而这些建议通常基于预期使用者的体重和一般活动水平。如果能够获得可比较的前脚掌和后跟刚度数据，就可以更好地了解不同商业假肢脚之间的差异，以及不同刚度类别和不同脚尺寸的脚之间的差异。因此，本研究比较了制造商指定的刚度类别和脚尺寸范围内的前脚掌和后跟线性刚度特性。对五种商业假肢脚进行了机械测试，涵盖了一系列刚度类别和三种脚尺寸。总共收集了 56 只假肢脚的数据。为了分别隔离脚跟和前脚掌部件的加载，在两个离散角度进行了测试。每个假肢脚加载了六个周期，同时收集了力和位移数据。前脚掌和后跟测量的刚度都与刚度类别显著相关（p=0.001）。没有证据表明刚度类别与测量刚度之间的关系因脚尺寸而异（刚度类别与尺寸交互作用 p=0.80）。然而，在刚度类别之间，预期和测量的刚度变化之间存在不一致（即，同一脚的连续刚度类别之间的刚度变化幅度有很大差异）。尽管统计结果支持平均而言，测量的刚度与刚度类别呈正相关，但力-位移数据表明，在连续类别之间，测量的刚度存在很大差异。因此，商业假肢的已发表的客观机械性能数据可能有助于临床医生在处方时使用。
