Comparison of Gait Kinematic and Temporospatial Measures Between Lock and Pin and a New Vacuum Suspension System in Transtibial Amputees

Walking in healthy populations has been characterized by symmetrical gait patterns and used to determine variability within pathological populations. Gait patterns of individuals with transtibial amputation are commonly asymmetrical due to the inability to completely replicate the physiological ankle with prosthetics; thus, contributing to inter-limb asymmetries. Currently, only a few studies have reported the effects of suspension systems on gait mechanics. In this study, functional differences between lock and pin (PIN) and a newly developed internal vacuum suspension system (Smart PUCKTM) (PUCK) during overground and treadmill walking were evaluated in five transtibial amputees. Statistically, no differences were found between groups in the distance walked during the six-minute walk test. However, clinically, the PUCK group tended to walk further compared to the PIN suspension system as suggested by the moderate effect size (0.42). Temporospatial asymmetries, stance and swing time, appeared to increase in the PUCK system compared to the PIN system but did not reach significance. The stance time symmetry index (SI) in the PUCK was more asymmetrical, thus approaching a significant difference compared to the PIN suspension system. However, stride length was remarkably similar between limbs in both systems. Kinematic asymmetries persisted in both suspension systems, but knee flexion was significantly greater in the PIN amputated limb during swing compared to the PUCK non-amputated limb. The type of suspension system does not appear to influence the knee angular velocity and hip angles and angular velocity. Differences in hip angular velocities were observed between the amputated and non-amputated limbs. These differences were attributed to the inability to replicate the biological limb, not the type of suspension system. Differences seen between suspension system may be attributed to the significantly greater mass in the PUCK and the use of a neoprene sleeve only used in the PUCK. Based on these outcomes, the type of suspension system may influence these individual’s functional performance during treadmill and overground walking. Further work should be conducted to focus on clinical performance in both suspension systems to contrast the outcomes with quality of life measures to better inform clinicians and patients of potential advantages of suspension systems