• Physical Therapy Korea
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• v.27 no.4
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• pp.241-249
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• 2020

Background: Prolonged standing during work causes a lower extremity pain and disorders. Patellofemoral pain syndrome (PFPS) is one of the common diagnoses of the knee pain. Although the etiology of PFPS is not completely understood, it is considered to be multifactorial. Objects: The purpose of this study was to investigate difference in strength of knee muscles, quadriceps:hamstring muscles strength ratio (Q:H ratio), asymmetry ratio of knee muscles strength and dorsiflexion range of motion (ROM) between standing workers with and without PFPS. Methods: Twenty-eight standing workers with PFPS and 26 age-, height-, and weight-matched standing workers without PFPS participated in this study. A tension sensor measured knee muscle strength, and motion sensor measured dorsiflexion ROM. The asymmetry ratio of knee muscles was calculated by a specific formula using the knee muscles strength of the dominant side and the sound side. An independent t-test was used to identify significant differences in the strength, ROM, Q:H ratio, and asymmetry ratio between the PFPS and normal groups. Results: The standing worker with PFPS have significantly lower dorsiflexion ROM (p < 0.000) and higher asymmetry ratio of the hamstring muscles strength (p < 0.000) compare to the standing worker without PFPS. No significant differences were seen in the strength of quadriceps muscle and hamstring muscles, Q:H ratio, and asymmetry ratio of quadriceps muscle strength. Conclusion: There was a significant difference in the asymmetry ratio of the isometric hamstring muscle strength. This finding suggests that the asymmetry ratio of isometric hamstring muscle strength may be more important than measuring only the hamstring muscle strength of the PFPS side. Furthermore, the results of this study showed a significant difference in dorsiflexion ROM between the standing industrial workers with and without PFPS. Dorsiflexion ROM and isometric hamstring muscle strength should be considered when evaluating the subjects with PFPS.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.64-71
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• 2021

Objective: This study investigated the different in isokinetic peak strength of the knee joint, and kinetics and kinematics in drop landing pattern of lower limb between the patellofemoral pain syndrome (PFPS) patients and normal. Method: 30 adult females were divided into the PFPS (age: 23.13±2.77 yrs; height: 160.97±3.79 cm, weight: 51.19±4.86 kg) and normal group (age: 22.80±2.54 yrs, height: 164.40±5.77 cm, weight: 56.14±8.16 kg), with 15 subjects in each group. To examine the knee isokinetic peak strength, kinematics and kinetics in peak vertical ground reaction force during drop landing. Results: The knee peak torque (Nm) and relative strength (%) were significantly weaker PFPS group than normal group. In addition, PFPS group had significantly greater hip flexion angle (°) than normal group. Moreover, normal group had significantly greater moment of hip abduction, hip internal rotation, and left ankle eversion than PFPS group, and PFPS group had significantly greater moment of knee internal rotation. Finally, there was significant differences between the groups at anteroposterior center of pressure. Conclusion: The PFPS patients had weakened knee strength, and which can result in an unstable landing pattern and cause of more stress in the knee joints despite to effort of reduce vertical ground reaction force.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.1
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• pp.35-38
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• 2014

Background: The case study examined the effect of a hip joint traction and hip posterolateral muscles strengthening on knee pain, range of motion, and lower extremity function scale of patients with patellofemoral pain syndrome (PFPS). Although PFPS has previously been attributed to quadriceps dysfunction, more recent research has linked this condition to impairment of the hip musculature and kinematic. Methods: Subject is a 27-years-old female with PFPS. Performed hip joint traction with belt and posterolateral muscles(hip abductors, external rotators) strengthening for 4 weeks, 3 times a week, once a day. Before and after the therapy, measurements were made on the visual analog scale (VAS) and of the ROM, and a lower extremity functional scale (LEFS) was conducted. Results: The results showed positive changes in VAS and range of motion and lower extremity functional scale. First VAS of knee changed from 6 to 2. Second hip joint range of motion showed that internal rotation recored from $53^{\circ}$ to $58^{\circ}$ and external rotation recorded from $32^{\circ}$ to $37^{\circ}$. Third The lower extremity functional scale showed before therapy of 44; after therapy, 63. Conclusion: The hip joint traction and hip posterolateral muscles strengthening was effective in alleviating knee pain, increasing ROM and Lower extremity functional scale of the PFPS patients.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.1
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• pp.31-39
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• 2021

Background: Patellofemoral pain syndrome (PFPS) is common knee disorder encountered in clinical: notably, altered hip biomechanic may contribute to PFPS. In this study, We investigated the effects of hip joint mobilization on pain, balance, and gait in patients with PFPS. Methods: Patients were randomly assigned to a control group (n=18) or an experimental group (n=20). Both groups received exercise therapy thrice a week for 4 weeks. The experimental group performed additional hip joint mobilization thrice a week for 4 weeks. Measurement were obtained in each patient pre-intervention and post-intervention (after 4 weeks). Results: The assessed items included the visual analog scale (VAS), one leg standing test (OLS), timed up and go test (TUG), and the 10m walk test (10MWT). Post-intervention assessment showed significantly improved results in both groups (p<.01). A significant intergroup difference was observed only in the results of the 10MWT (p<.05). Conclusion: Our results indicate that hip joint mobilization with exercise therapy may be useful to improve PFPS.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.63-73
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• 2015

The purpose of this study was to examine EMG activities and VMO/VL ratio of the vastus medialis oblique, and vastus lateralis during step up exercise according to ankle and knee positions in soccer players with patellofemoral pain syndrome. Methods: Subject(patellofemoral pain syndrome, PFPS: n=8 and without PFPS, non PFPS; NPFPS: n=8) perfomed step up exercise at each knee and ankle position(knee flexion $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$, ankle internal rotation $30^{\circ}$, neutral, and external rotation $30^{\circ}$) while EMG activity was collected. The EMG signals were expressed by the % maximal voluntary isometric Contraction(%MVIC) values. Statistical analysis consisted of two way repeated measures analysis of variance with post hoc analysis. Results: Main results were as follows: 1) EMG of VMO, and VL was tend to be lower in PFPS compared to NPFPS. 2) EMG of VMO and VL with knee flexrion $60^{\circ}$ was significantly higher the results with knee flexion $30^{\circ}$, and $90^{\circ}$. VMO and VL with ankle external rotation $30^{\circ}$ was significantly higher the results with internal rotation $30^{\circ}$ and neutral position. Conclusion: Considering the EMG activity was reduced due to the to the PFPS and that performing step up with knee flexion $60^{\circ}$ with ankle external rotation $30^{\circ}$ position may provide the most effective condition for patients with patellofemoral pain syndrome.

• Physical Therapy Korea
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• v.23 no.1
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• pp.11-19
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• 2016

Background: Investigation in gender differences of kinetics and kinematics for individuals with patellar femoral pain syndrome (PFPS) was not sufficiently performed. Objects: The purpose of this study is that whether there is a difference depending on gender from muscle activity and strength and knee valgus angle during controlled single-leg squat which is widely used as clinical movement test for the patient with PFPS. Methods: 20 young adults (10 men, $20.0\pm}2.1$years; 10 women, $20.4{\pm}2.1$years) with PFPS were voluntarily recruited in this study. Muscle activity and strength and knee valgus angle were collected during single-leg squat. Independent t-test and Mann-Whitney test were used to compare the differences between groups of male and female. Results: Rectus femoris (t=-2.204, p=.041) and vastus medialis oblique (t=-2.151, p=.045) muscle activity of women were significantly higher than male group. Normalized muscle strength of hip and knee muscles showed a significant difference between men and women (p<.05). Valgus angle of the knee in women (t=-2.450, p=.025) were increased significantly than men. Conclusion: The therapist would consider the characteristics of these gender differences during performing movement test, exercise, and education for the individuals with PFPS.

• Physical Therapy Rehabilitation Science
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• v.7 no.2
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• pp.61-66
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• 2018

Objective: Patellofemoral pain syndrome (PFPS) is a condition that is characterized by patellar discomfort or pain that is aggravated during certain activities such as ascending/descending stairs. The Patellofemoral Disability Index (PDI) was developed to assess the effect of pain on functional activities in individuals with PFPS. The objectives of the current study were to determine the internal consistency, test-retest reliability, and validity of this index. Design: Cross-sectional study. Methods: Forty-one subjects who had PFPS with a mean age of $28.8{\pm}5.0years$ and a mean body mass index of $25.6{\pm}4.7kg/m^2$ participated in the study. All subjects were concurrently enrolled in a clinical trial for which they were instructed to complete hamstring-resistance exercises for 4 weeks. Over the course of the intervention, they completed both the PDI and the Oswestry Disability Index (ODI) at baseline after two weeks, and after four weeks. Pearson correlation coefficient was used to assess the criterion validity. Cronbach's ${\alpha}$ was used to examine the internal consistency. Intraclass correlation coefficients with 95% confidence interval were computed to examine test-retest reliability. Results: Subjects' responses within both the PDI and the ODI yielded Pearson correlation coefficient values that were positive and highly significant (range, 0.73-0.97; p<0.001). There was a high level of internal consistency (Cronbach's ${\alpha}{\geq}0.8$), with the exception of stair climbing (Cronbach's ${\alpha}=0.65$). Intraclass correlation ranged from 0.87 to 0.92, indicating high levels of test-retest reliability. Conclusions: The PDI is a valid, reliable, and feasible method of assessing pain and functional ability in patients with PFPS.

• Journal of Korean Physical Therapy Science
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• v.30 no.3
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• pp.59-71
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• 2023

Background: This study was to investigate the effects of coordinative locomotor training(CLT) using elastic bands on pain, dynamic balance, muscle strength, and muscle activity of female college students with patellofemoral pain syndrome(PFPS). Design: Randomized Controlled Trial Methods: Twenty-six female college students with PFPS were assigned randomly to an experimental(n=13) or control(n=13) group. The experimental group performed CLT using an elastic band. The control group performed squat exercises to strengthen muscle strength. The 30-minute inter- vention was applied a total of twelve times, three times a week for four weeks. All subjects measured the pain, the muscle strength, the dynamic balance, and the muscle activity(VL/VM ratio) before and after intervention. A paired t-test was used for the determination of differences before and after treatment, and an independent t-test was used for the determination of differences between treatment groups. Results: As a result of comparison within groups, the experimental group showed significant differences in pain, muscle strength, dynamic balance, and VL/VM ratio after the experiment(p<0.05), and the control group showed significant differences in pain, muscle strength, and dynamic balance after the experiment(p<0.05). In comparison between the two groups, the experimental group showed more significant differences in pain, dynamic balance, and VL/VM ratio than the control group(p<0.05), and the control group showed more significant differences in muscle strength than the experimental group(p<0.05). Conclusion: Based on these results, CLT using elastic bands effectively improved the pain, muscle strength, dynamic balance, and VL/VM ratio of female college students with PFPS.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.3
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• pp.89-98
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• 2021

Purpose: The purpose of this study was to determine the effects of electromyography (EMG)-biofeedback based closed kinetic chain exercise (CKCE) on quadriceps muscle activity and dynamic balance ability in patellofemoral pain syndrome (PFPS). Methods: Thirty subjects with PFPS were included and they were divided into EMG-biofeedback using CKCE (Group I) and squat exercise using CKCE (Group II), each group consisted of 15 patients. Group I and Group II was performed by the patients for three times a week, for six weeks. sEMG was used to measure quadriceps muscle activity and star excursion balance test (SEBT) was used to measure dynamic balance ability. Results: According to the results of the comparisons between the groups, after intervention, quadriceps muscle activity and dynamic balance ability were significantly higher in Group I than in the Group II. Conclusion: Findings of this study suggest that EMG-biofeedback using CKCE that provides real-time biofeedback information on muscle contraction may have a beneficial effect on selective muscle strength of vastus medialis oblique muscle and dynamic balance ability in PFPS.

• Physical Therapy Korea
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• v.12 no.2
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• pp.11-19
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• 2005

Patellofemoral pain syndrome (PFPS) is often attributed to malalignment and maltracking of patella within the patellofemoral joint. Most exercise for PFPS has focused on selectively strengthening the vastus medialis oblique muscle (VMO). This study was designed to identify the effect of medial, lateral wedge and difference of Quadriceps angle (Q-angle) on vastus medialis oblique/vastus lateralis muscle (VL) activity ratios. The subjects were twenty young adult males who had not experienced any knee injury. They were asked to perform isometric contraction exercises in three postures using medial and lateral wedge. The EMG activity of the VL and VMO were recorded in three postures by surface electrodes and normalized by %MVC values derived from seated, isometric knee extensions. The normalized EMG activity levels (%MVC) of the VL and VMO for the three postures of the lower extremities were compared using 2-way repeated measures ANOVA with 1 between-subject factor (group), and 1 within-subject factor (wedge). Results of repeated measures of ANOVA's revealed that the medial wedge isometric contraction exercise produced significantly greater EMG activity of VMO/VL ratios in Group I (Q-angle $18^{\circ}$ or less) (p<.05). But, the medial wedge isometric contraction exercise was no significant difference of VMO/VL ratios in Group II (Q-angle $19^{\circ}$ or more) (p>.05). These results have important implications for selective VMO muscle strengthening exercises in PFPS patients.