Background: Despite several studies with different methods, the effect of functional knee braces on knee joint kinematics is not clear. Direct visualization of joint components through medical imaging modalities may provide the clinicians with more useful information. Objectives: In this study, for the first time in the literature, video fluoroscopy was used to investigate the effect of knee bracing on the sagittal plane kinematics of anterior cruciate ligament (ACL) injured patients. Patients and Methods: For twelve male unilateral ACL deficient subjects, the anterior tibial translation was measured during lunge exercise in non-braced and braced conditions. Fluoroscopic images were acquired from the subjects using a digital fluoroscopy system with a rate of 10 fps. The image of each frame was scaled using a calibration coin and analyzed in AutoCAD environment. The angle between the two lines, tangent to the posterior cortexes of the femoral and tibial shafts was measured as the flexion angle. For the fluoroscopic images associated with 0°, 15°, 30°, 45° and 60° knee flexion angles, the relative anterior-posterior configuration of the tibiofemoral joint was assessed by measuring the position of landmarks on the tibia and femur. Results: Results indicated that the overall anterior translations of the tibia during the eccentric (down) and concentric (up) phases of lunge exercise were 10.4 ± 1.7 mm and 9.0 ± 2.2 mm for non-braced, and 10.1 ± 3.4 mm and 7.4 ± 2.5 mm, for braced conditions, respectively. The difference of the tibial anterior-posterior translation behaviors of the braced and non-braced knees was not statistically significant. Conclusion: Fluoroscopic imaging provides an effective tool to measure the dynamic behavior of the knee joint in the sagittal plane and within the limitations of this study, the pure mechanical stabilizing effect of functional knee bracing is not sufficient to control the anterior tibial translation of the ACL deficient patients during lunge exercise. Keywords: Kinematics; Brace; Anterior Cruciate Ligament; Fluoroscopy; Knee Joint

Would there be differences in muscle activation between healthy subjects' (HS) dominant leg and transfemoral amputees' (TFA) intact-leg/contralateral-limb (IL) during normal transient-state walking speed? The muscle activation patterns are obtained by calculating the linear envelope of the EMG signals for each group. The activation patterns/temporal changes are compared between-population using statistical parametric mapping (SPM). Individual muscle activity showed significant differences in all muscles except vastus lateralis (VL), semitendinosus (SEM) and tensor fascia latae (TFL) activities. The information could be used by the therapists to prevent secondary physical conditions and prosthetic companies to improve the mobility of the amputees.

The number of lower limb amputations is increasing significantly in developed countries. The knowledge of muscle synergy in subjects with loss of muscles could help to understand the general neural strategy underlying muscle coordination in walking. The aim of this study was to investigate the differences in healthy subject's dominant leg, amputee's intact leg (IL) and the amputee's prosthetic leg (PL) muscles using synergy analysis. Concatenated non-negative matrix factorization (CNMF) was performed to divide the surface electromyography (sEMG) data obtained from 6 upper knee and 4 shank muscles into muscle synergy (S) and activation coefficient profile (C) during walking. The difference in S showed low to high correlations inter-subjectively. The high correlation suggests that the central nervous system (CNS) activates the same groups of muscles synergistically. Amputee's muscle alterations due to inadequate proprioceptive feedback, weight bearing deficiency in PL and prosthesis type could lead to a low correlation in S between groups. The C showed to be statistically significantly different in some regions of the gait cycle (GC). These findings could provide valuable information for rehabilitation purposes and development of a synergy-based controller from sEMG for future generations of prostheses.

The use of functional knee braces for returning to sports or during demanding activities following anterior cruciate ligament rupture is common; yet despite being commonly prescribed, its mechanism of action remains unknown. To examine the effect of functional knee braces on mean muscle activity when performing lunge exercises. Pre-/post-test (within-subject research design). A total of 10 male participants with unilateral isolated anterior cruciate ligament deficiency participated. Electromyographic activities of six muscles around the knee were recorded during lunge exercises, with and without wearing a custom functional knee brace. The lunge cycle movement was subdivided into three phases: eccentric, isometric, and concentric. The quadriceps and hamstrings were no different in the braced and unbraced conditions. When braced, the mean amplitude of the medial gastrocnemius was significantly lower throughout the whole movement (p = 0.01) and during the concentric (p = 0.006) and eccentric (p = 0.028) phases, but not within the isometric phase. The lateral gastrocnemius was found to have lower mean amplitude in the isometric phase (p = 0.044). With its origin on the medial femoral condyle, perhaps reduced medial gastrocnemius activity may better guide knee rotation and assist the joint achieving a healthier kinematic pattern. Lower medial gastrocnemius activity may facilitate lower medial compartment contact pressure, for which greater loading is known to increase the risk of osteoarthritis in anterior cruciate ligament–deficient (ACLD) knees. However, further research is needed.