|Title:||Biomechanical efficacy of knee bracing on joint kinetics and kinematics, postural steadiness and wearing perception|
|Advisors:||Zhang, Ming (BME)|
Hong Kong Polytechnic University -- Dissertations
|Department:||Interdisciplinary Division of Biomedical Engineering|
|Pages:||vi, 110 pages : color illustrations|
|Abstract:||Frequent knee pain affects approximately 25% of adults, limits function and mobility, and impairs quality of life. Uneven knee loading can accelerate the degenerative process of knee osteoarthritis and result in aggravation of knee pain. Knee bracing is one of the most widely used non-pharmacologic alternatives in prophylaxis and management of knee pain through improving mechanical loading of knee joint and proprioception. However, the biomechanical efficacy of knee bracing on knee joint and wearing perception remains controversial in daily and clinic applications. The purpose of this study is to investigate the biomechanical effectiveness of knee bracing on joint kinetics and kinematics, postural control and subjective wearing perception through conducting experimental 3D gait analysis, postural steadiness estimation and questionnaire survey. The results from this study were expected to advance the understanding of knee bracing performances, and to provide a foundation for design and development of new knee bracing and related orthoses products for prevention and physical therapy.In the current 3D gait experimental study, four different types of knee bracing were investigated in ten healthy participants. The studied knee bracing included supportive knee braces (i.e. knee sleeve BI with double bilateral stands without knee protruding pad; and knee sleeve BII with sing bilateral stands with knee protruding gel pad), and prophylactic knee braces (i.e. hinged knee brace BIII with medial and lateral stays and non-elastic straps; and hinged wraparound hinged knee brace BIV with medial and lateral stays with hypertension stop and non-elastic circular straps). Sixteen retro-reflective markers were attached to the seven body segments (pelvis, thigh, knee, shank, ankle, forefoot and heel) to monitor the motion of lower extremities. Eight infrared cameras and two force platforms were used to identify kinetics and kinematics of knee joint with and without knee bracing in level walking, including knee joint related moments, angles, ground reaction forces in three anatomic planes (sagittal, coronal and transverse) and temporal-spatial variables. One-way repeated measures analysis of variance (ANOVA) and post-hoc linear contrast were performed to identify the biomechanical efficacy of different knee bracing on the aforementioned variables related to knee joint.The results showed that the application of knee bracing did not significantly variate the studied peak knee moments in stance phase except for knee valgus moment. A significant reduction in knee valgus (abduction) moments were found in the braces BIII (p = 0.048) and BIV (p = 0.049), compared with non-braced (control) condition; and the intervention of knee bracing generated a decreasing tendency in knee flexion angles corresponding to the peak varus-valgus moments. It implied that the studied knee bracing may reduce the load over lateral femoro-tibial compartment of knee joint, thus potentially relieving pain symptoms of valgus (knock) knee in the realistic use. The results of kinematic and spatial-temporal studies indicated that the knee bracing did not significantly affect knee motion in sagittal plane and walking performances (e.g. stride length, step length, cadence, cycle time, and walking velocity); while knee braces BI, BII and BIII significantly reduced the difference values (D-values) of knee joint angles between the stages of heel strike and heel off in the coronal plane by 60.9%, 46.5% and 52.5% respectively, as compared with the control. It was suggested that studied knee bracing could prevent varus-valgus deformation and stabilize knee joint without restraints of knee motion in level walking.|
A new method was developed to assess the postural steadiness by means of F-scan plantar pressure system. The duration of time of single-leg stance (TSLS) was recorded under different bracing conditions; and foot sway degree was obtained in terms of the tested peak contact plantar pressure and the calculated standard deviation of instaneous pressure change rate (S.D. of ICRpp) during SLS. The results indicated that the application of knee bracing significantly increased the duration time during SLS by 15.81-29.88 sec., and significantly reduced the foot sway degree by 14.3-42.9% in SLS, especially for the braces BI and BIV, as compared with non-braced condition. It implied that the intervention of the tested knee bracing could improve the joint-position sense (proprioception) and the postural control in static position. The subjective assessment was conducted by applying the designed questionnaires with fifteen Liker items covering 5 aspects, including wearing comfort and fitting, tactile perception, wear behavior, support and stable feeling, and preferences towards knee bracing products. The results indicated that the participants preferred the knee bracing with low profile appearance, simple and stylish design and easy to operate. The knitted supportive knee braces (pullover BI and BII with bilateral spiral stands) were more acceptable with significantly higher scores on aspects of 'wearing comfort', 'fitting', 'freedom in movement' and 'satisfied handle of shell materials'.Wraparound shell structure and mechanical supporting elements (e.g. non-elastic straps and bilateral hinges) allowed the braces BIII and BIV to generate more stable feel at the knee joint and to be more easily donned on and off; while more time was consumed and potential limitations could exist in knee extension-flexion movement.The findings from the current study enhanced the understanding on biomechanical efficacy of knee bracing on joint kinetics and kinematics, postural control and subjective wearing perception, and provided a valuable foundation for the following design and development of new knee bracing with improved therapeutic function and wearing comfort for lower extremities.
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