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INFLUENCE OF A FUNCTIONAL KNEE BRACE ON LOWER EXTREMITY KINETICS: A PRELIMINARY STUDY

Campbell, B M.1; Armstrong, C W.1; Cipriani, D1

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Medicine & Science in Sports & Exercise: May 2002 - Volume 34 - Issue 5 - p S177
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Functional knee braces (FKB) are often used during ACL rehabilitation to assist in providing a functionally stable knee. Previous research has indicated that they contribute to this, in part, by decreasing the extensor torques and powers at the knee. This protective mechanism has been demonstrated in normals and those with ACL deficiency immediately after donning an FKB. Although these changes have been shown to occur, what is not known is the degree to which they persist beyond this initial time period. Such information may reflect on the actual protective mechanisms involved in the use of FKB's.

PURPOSE:

To determine if the alterations in gait caused by an FKB are influenced by involvement in exercise and/or duration of use.

METHODS:

Eight healthy young adults participated in this investigation. Four subjects were in each group: control (CON = no brace) and experimental (EXP = brace). Each subject in the EXP was fitted, according to manufacturers' guidelines, with an FKB. Both EXP and CON performed a one-hour exercise protocol, which was divided into three 20-minute increments. Prior to the protocol and following each 20-minute increment a multi-trial jogging gait analysis was performed to help determine the affects of the brace and exercise on the individuals gait pattern. Following the protocol each subject was asked to return to the lab twenty-four hours later to perform a final multi-trial jogging gait analysis. A total of six multi-trial gait analyses (six time points) were performed. Gait data was collected using a six camera 3-D video system, a gait analysis software package and two force platforms.

RESULTS:

Analysis of the data indicated subtle differences between the two groups for vertical ground reaction forces and ankle, hip and knee joint moments (KJM). This was most evident at time point four, where the KJM of the EXP group decreased 3% relative to time point three. In contrast the CON group evidenced an % increase in the knee moment for this time interval. Similarly, over the twenty-four hour time period the KJM of the EXP group declined by 2% and that of the CON increased by 4%.

CONCLUSION:

Collectively the trends that were observed were consistent with previous research in indicating a decrease in the KJM in the EXP group that may be beneficial in protecting the ACL. Additionally, the fact that these trends were observed across bouts of exercise and over a twenty-four hour time period support the persistence of the FKB effect.

©2002The American College of Sports Medicine