The effect of damping in prosthetic ankle and knee joints on the biomechanical outcomes: A literature review

Background: Given the growing number of variable-damping prosthetic knee and ankle components and broad number of potential biomechanical outcomes, a systematic review is needed to assess advantages of damped knee and ankle units over non-damped prostheses. Objectives: This study provides an overview of the biomechanical outcomes associated with the use of prosthetic knees and ankles with damping mechanisms in individuals with lower limb amputation. Study design: Literature review. Methods: A systematic search was performed through PubMed, Science Direct, Web of Science, Cochrane, and Scopus databases from June 1994 to March 2016. The level of evidence of each article was assessed using a 13-element checklist for evaluating non-randomized controlled trials for quality assessment. Afterward, the studies were classified as A-level, B-level, or C-level based on total score and positive scores from certain key categories. Results: In total, 22 papers remained for the quality assessment based on the inclusion criteria. In total, 15 studies scored sufficiently high quality scores to be classified. One article scored as A-level, eight as B-level, and six as C-level. In total, 10 studied knees and 5 examined ankles. Sample sizes ranged from 5 to 28 subjects. Conclusion: Available studies were evaluated in detail and biomechanical outcomes were extracted from the studies that met criteria. Results of this review indicate that study methodology and outcome measures were heterogeneous across reviewed papers. This could be an explanation for inconsistent findings of the reviewed studies. Only self-selected gait speed showed a consistent difference when dampers were applied to the leg. Thus, further research is required in this area. Clinical relevance This study provides an overview of evidence related to prosthetic knee and foot/ankle components with damping attachments. Research related to biomechanical outcomes is of great importance for researchers and practitioners in this area. The studies drew mixed conclusions, but walking speed was consistently different for damped versus non-damped components.