Background: Total knee arthroplasty (TKA) recovers the alignment of the knee joint, but fails to automatically restore the alignment and function of the hip and ankle joints. It may affect the alignment and stability of the knee joint, therefore therapeutic intervention in hip and ankle joint is necessary for the rehabilitation process after TKA. Objects: The aim of this study was to comparison of the effects of the two exercise methods on the coronal plane alignment after TKA. This study conducted an experiment by dividing subjects into a lower extremity isometric co-contraction group (LEIC) and a quadriceps isolated isometric contraction (QIIC) group. Methods: A total of 37 subjects were randomly assigned to the LEIC (n1=19) or the QIIC (n2=18). Exercise was applied to five times per week for three weeks, starting on the eighth day after surgery. Range of motion exercises were performed as a common intervention and then each group performed quadriceps isometric contraction exercises with 10 sets of 5 repetitions. Radiological imaging was performed prior to surgery, one month and six months after surgery. In addition, the hip-knee-ankle angle (HKA) and tibiotalar angle (TTA) were measured. Results: The HKA was close to neutral in the LEIC rather than the QIIC (p<.05). The LEIC showed varus and the QIIC exhibited valgus TTA (p<.05). In a comparison of HKA and TTA over time, there was no significant change in either group (p>.05). According to the comparison of the TTA before surgery, the LEIC showed significant changes in the varus direction (p<.05), while there was no significant change in the QIIC (p>.05). Conclusion: The LEIC method triggered changes in the TTA and brought the HKA close to the neutral. Thus, LEIC is more effective than QIIC in creating stability in the coronal plane alignment of the knee and ankle joints after TKA.

The purpose of this study was to assess the influence of patellar height on quadriceps muscles' electromyography (EMG) activity during a squat exercise in adults with patella baja. For the study, we recruited 15 volunteers who had patella baja on the right side. We measured the EMG activity of the right rectus femoris, vastus medialis oblique, and vastus lateralis muscles during squat exercises under two conditions, specifically with and without an infra-patellar strap. The infra-patellar strap was applied below the tested patella to elevate the patella to a normal height. A paired t-test was used to compare the effects of patella height on EMG activity of the quadriceps muscles. The EMG activity of the rectus femoris (RF), vastus medialis oblique (VMO), and vastus lateralis (VL) muscles were significantly decreased during the squat exercise with the infra-patellar strap compared to the same exercise without the infra-patellar strap (p<.05), while the VMO/VL ratio was not different significantly between two conditions (p>.05). The findings of this study suggest that an infra-patellar strap may benefit people with patellar baja, as changes in patellar height could improve the efficiency of the quadriceps muscles.

This study examined the vastus medialis oblique (VMO) and the vastus lateralis (VL) onset time differences (OTD) during quadriceps contraction in different hip positions. Twelve healthy subjects were recruited (four men, eight women). Surface EMG activities of the VMO and VL were measured during a quadriceps strengthening exercise in a long sitting condition and in a sitting at a chair with feet hanging condition. For each condition, subjects were tested in two hip positions (neutral and adduction). The OTD between the two muscles was calculated for each condition, by subtracting the onset time of the VL from the VMO. Therefore, the negative value of OTD represent earlier EMG onset of the VMO compared to the VL. The OTD was not significantly different between the hip neutral and the hip adduction position in the long sitting condition (p=.064). However, the OTD was significantly different between the hip neutral position (15.83±109.51 ms) and hip adduction position (-5.58±121.08 ms) during the sitting at a chair with feet hanging condition (p=.047). The negative OTD value in the hip adduction condition during quadriceps strengthening exercises is the result of earlier onset of the VMO than VL. Therefore, quadriceps contraction in the hip adduction position can prevent the risk of patella lateral tracking. We expect that quadriceps strengthening exercise in the hip adduction position will be a safe way to prevent patellofemoral pain syndrome resulting from abnormal patella lateral tracking.

The purpose of this study was to suppose basis data the influence of different chair type and pelvic control on quadriceps muscle activity and strength during knee joint extension isometric exercise in hemiplegic patients. This research were investigated in ten healthy adults and tens hemipelgic patients. Surface electromyography (EMG) and Biodex system were used to collect kinematic data and muscle activity, respectively. Independent t-test, paired t-test and one-way repeated ANOVA were used to determine a statistical significance. The results showed as follows: (1) Posterior pelvic angles in healthy group and hemiplegic group were significantly different on isokinetic equipment (p<.05). (2) Different chair type and pelvic control on quadriceps muscle activity and strength were significantly different in hemiplegic patients (p<.05). From the result of this research, posterior pelvic angle control during knee joint extension isometric exercise in hemiplegic patients on isokinetic equipment is necessary to increase quadriceps muscle strength in hemiplegic patients.

Physical therapists have been using biofeedback training to induce improvements in various circumstances. The purpose of this study was to compare the effects of visual and tactile feedback using electrical stimulation on quadriceps strength. Nineteen women without known impairment of the neuromusculoskeletal system volunteered for this study. Subjects were randomly allocated into three groups: visual feedback, tactile feedback, and control group. The torque of isometric knee extension force was measured. Subjects were asked to exert the maximal isometric contraction force of quadriceps over a 30 second period. The resting period of 10 minutes was given after the maximal isometric contraction to avoid the muscle fatigue. In between groups comparison, significant differences of the peak torque and the torque area were found on the performance of the maximal isometric contraction of quadriceps (p<.05). The values peak of torque and torque area were significantly higher during visual feedback than tactile feedback. The results of this study suggest that visual feedback is more powerful than tactile feedback (p<.01).

The purpose of this study was to determine the effect of electrical stimulation biofeedback on motor learning of quadriceps muscle isometric exercise in 3 patients who have undergone total knee replacement surgery. A multiple baseline design across subjects was used. The electrical stimulation biofeedback was provided with each patient during quadriceps isometric exercise, which last 10 to 14 sessions with 10 repetitions each sessions. After training patients received 4 retention tests. Maximum muscle activity was measured pre- and post- electrical stimulation biofeedback training and retention test to evaluate the effect of biofeedback training. Maximum isometric muscle activity of quadriceps was increased after electrical stimulation biofeedback training in all subjects. The results indicate that a electrical stimulation biofeedback training is a useful method to improve motor learning of quadriceps isometric exercise in total knee replacement.

The purposes of this study were to compare the electromyographic activities from the rectus femoris, vastus medialis oblique portion, vastus medialis longitudinal portion, and vastus lateralis during straight leg raising (SLR) and quadriceps setting (QS) exercise and to determine which exercise is more effective to selectively strengthen the vastus medialis. Thirty two healthy subjects <19 men, 13 women) participated in the study. All participants performed SLR and QS exercises while electromyographic activity was recorded from EMG surface electrodes. Statistical analysis demonstrated significantly greater values for the vastus medialis oblique portion, vastus medialis longitudinal portion, and vastus lateralis activities during QS exercise than for those during SLR exercise. However, the rectus femoris muscle activity between SLR and QS exercises was not significantly different. The ratios of vastus lateralis to vastus medialis during SLR and QS exercise were not significantly different. These results show that QS exercise is more effective for strengthening the quadriceps muscle on the whole than the SLR exercise. As for selective methods of strengthening vastus medialis specifically, both SLR and QS exercises are useful.

The purpose of this study was to determine whether the vastus medialis oblique muscle(VMO) had greater electrical activity than the vastus lateralis muscle(VL) when hip adduction and knee extension exercise were performed. Electrical activity of the VMO and VL was measured on 42 healthy subjects (28 men, 14 women) during maximal voluntary isometric contractions of hip adduction and knee extension by an EMG-BIOFEEDBACK. The results showed that the electromyographic activity of the VMO was significantly greater than that of the VL during the hip adduction exercise. Differences noted with knee extension by performing hip adduction exercises. Isometric hip adduction exercises, therefore, may be advisable in the treatment of patients with patellofemoral pain.