Transtibial Amputees Develop Strategies To Perform Sit-To-Stand Tasks

Unable to use the same movement strategies during sit-to-stand tasks as healthy, non-amputated individuals, transtibial amputees develop new strategies to perform these tasks, such as using more impaired postural control on their amputated limb and reducing force exerted by the legs, according to a recently published study.

“Going from a seated to standing position is an essential movement for participation in many activities of daily living. Performing this movement sufficiently is considered to be a key determinant of functional fitness and independence,” İlkşan Demirbüken, PhD, PT, assistant professor at Marmara University, Istanbul, Turkey, told O&P Business News. “People with transtibial amputations for any reason have to perform sit-to-stand movement several times in a day, which is almost similar to healthy individuals. However, transtibial amputees have biomechanical and musculoskeletal limitations compared with healthy non-amputated individuals, which can lead to using different movement strategies to perform sit-to-stand activity. We thought that the preferred motor strategies to perform this task by transtibial amputees should be well identified in order to provide a valuable insight into motor control, so that it will be possible to avoid the non-amputated limb from the secondary musculoskeletal impairments in the scope of preventive rehabilitation by improving their ability to stand up properly.”

Sit-to-stand evaluation

Researchers evaluated sit-to-stand movement in 12 male unilateral transtibial amputees (TTAs) and 19 healthy individuals in terms of weight transfer time, weight-bearing symmetry, sway velocity and rising index by using the Balance Master system.

Both amputees and non-amputees exhibited similar weight-bearing transfer times during the sit-to-stand movement, according to study results. However, when compared with healthy individuals, weight-bearing symmetry values were almost twice as high in TTAs, and they had an increased sway velocity and a significantly lower rising index during sit-to-stand movement.

Whereas knee extensor strength of the sound limb of TTAs were similar to healthy participants, study results showed knee extensor strength of the amputated limb was lower than the sound limb.

“There is little research on movement strategies of sit-to-stand task in unilateral transtibial amputees and they just focused on weight-bearing symmetry,” Demirbüken said. “Parallel to the findings of previous studies we also demonstrated that transtibial amputees had more weight-bearing asymmetry than healthy ones during sit-to-stand task. But we thought that a successful sit-to-stand movement is also related with postural control, weight transfer time and force exerted by legs. The results of all parameters we assessed were parallel to our hypothesis.”

Insight into motor components

The researchers believe these study results may provide new insight into the motor components of sit-to-stand movement in individuals with transtibial amputation by demonstrating a significant difference in postural sway values and weight-bearing symmetry between transtibial amputees and healthy individuals during sit-to-stand tasks. However, the researchers did not estimate the relationship between sway velocity and weight-bearing symmetry and suggested future research investigate this relationship in transtibial amputees during sit-to-stand tasks.

Although the results of the present study showed the altered movement strategies for transtibial amputees during sit-to-stand tasks, according to the researchers, further studies are required to develop sit-to-stand training protocols specific to transtibial amputees and new rehabilitation approaches, including a combination of balance training and weight-bearing exercises.

“The results of this study not only support weight-bearing asymmetry in persons with transtibial amputation but also indicated a difference in movement strategy during sit-to-stand activity, including postural control and force exerted by legs parameters of sit-to-stand activity,” Demirbüken said. “From a physical therapist’s perspective, we strongly recommend evaluating sit-to-stand movement in people with transtibial amputation routinely like gait disorders in rehabilitation clinics as it is one of the most frequently used daily living activity.” — by Casey Tingle

For more information:
Özyürek S. Prosthet Orthot Int. 2013;doi:10.1177/0309364613497742.

Disclosure: Demirbüken has no relevant financial disclosures.

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