Patellofemoral Pain, PFP
Conditions
Keywords
whole body vibration, knee
Brief summary
Patellofemoral Pain Syndrome (PFPS), or anterior knee pain, is one of the most common disorders affecting the lower extremities. Currently, there is no established "gold standard" treatment for PFPS. However, various interventions-including strengthening of the hip and knee muscles (e.g., hip abductors, external rotators, and knee extensors), taping, bracing, foot orthoses, manual therapy, acupuncture, blood flow restriction training, and conventional physical agents (e.g., ultrasound, cryotherapy, neuromuscular electrical stimulation, laser therapy, electromyographic biofeedback, etc.)-have been reported to provide meaningful clinical benefits. Strengthening of the hip and knee muscles alone has been shown to improve both pain and function in the short, medium, and long term. In recent high-quality studies, hip and knee muscle strengthening has been recognized as an effective "classical" treatment approach for PFPS. Regarding the mechanism of pain relief, previous research suggests that strengthening these muscles may alleviate pain by stabilizing patellar motion and/or reducing pressure on the patellofemoral joint. Similar to traditional resistance training, whole-body vibration (WBV) training is an alternative method for muscle strengthening. WBV platforms can generate vertical vibrations that stimulate tonic vibration reflexes through muscle spindles, thereby activating homonymous alpha motor neurons and inducing reflex muscle contractions. As a result, increased motor unit recruitment enhances the excitability of muscle spindles, leading to improved muscle strength. Additionally, WBV training can improve muscle balance, strength, and function. Therefore, combining WBV with hip and knee strengthening exercises may represent a more effective treatment strategy for PFPS. The aim of this study is to evaluate whether the combination of WBV and hip-knee muscle strengthening is more effective in reducing pain and improving function than hip-knee strengthening alone.
Detailed description
Patellofemoral Pain Syndrome (PFPS), or anterior knee pain, is one of the most common disorders affecting the lower extremities. Currently, there is no established "gold standard" treatment for PFPS. However, various interventions-including strengthening of the hip and knee muscles (e.g., hip abductors, external rotators, and knee extensors), taping, bracing, foot orthoses, manual therapy, acupuncture, blood flow restriction training, and conventional physical agents (e.g., ultrasound, cryotherapy, neuromuscular electrical stimulation, laser therapy, electromyographic biofeedback, etc.)-have been reported to provide meaningful clinical benefits. Strengthening of the hip and knee muscles alone has been shown to improve both pain and function in the short, medium, and long term. In recent high-quality studies, hip and knee muscle strengthening has been recognized as an effective "classical" treatment approach for PFPS. Regarding the mechanism of pain relief, previous research suggests that strengthening these muscles may alleviate pain by stabilizing patellar motion and/or reducing pressure on the patellofemoral joint. Similar to traditional resistance training, whole-body vibration (WBV) training is an alternative method for muscle strengthening. WBV platforms can generate vertical vibrations that stimulate tonic vibration reflexes through muscle spindles, thereby activating homonymous alpha motor neurons and inducing reflex muscle contractions. As a result, increased motor unit recruitment enhances the excitability of muscle spindles, leading to improved muscle strength. Additionally, WBV training can improve muscle balance, strength, and function. Therefore, combining WBV with hip and knee strengthening exercises may represent a more effective treatment strategy for PFPS. The aim of this study is to evaluate whether the combination of WBV and hip-knee muscle strengthening is more effective in reducing pain and improving function than hip-knee strengthening alone.
Interventions
DEVICEWhole body vibration
In this group, prior to the patient stepping onto the platform, the practitioner will turn off the vibration motor of the device and activate an external motor (which is not in contact with the WBV device, has no effective vibration capability, and only produces sound), installed by our team. Since the visual display of the device remains active, patients will not be aware that the actual vibration function is disabled, thereby preventing any bias related to device inactivity.
In this group, prior to the patient stepping onto the platform, the practitioner will turn off the vibration motor of the device and activate an external motor (which is not in contact with the WBV device, has no effective vibration capability, and only produces sound), installed by our team. Since the visual display of the device remains active, patients will not be aware that the actual vibration function is disabled, thereby preventing any bias related to device inactivity.
Sponsors
Pamukkale University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
No
Inclusion criteria
* Aged between 18 and 40 years, * Diagnosed with unilateral Patellofemoral Pain Syndrome (PFPS), * Reporting anterior knee pain or pain behind the patella in at least two of the following activities: ascending stairs, jumping, running, squatting, kneeling, prolonged sitting, \- Positive results in at least two of the following clinical tests: Eccentric step-down test, Patellar border tenderness test, Patellar grind (Clarke's) or apprehension test, * Ability to understand the procedures, potential benefits, and possible adverse effects, * Willingness to participate in the treatment program.
Exclusion criteria
* Severe injury or pathological changes in knee structures (e.g., ligaments, menisci, patellar tendons, iliotibial bands, joint capsules, or plicae), * History of significant trauma or surgery involving the knee or lower extremity, * History of patellar dislocation or subluxation, * Diagnosis of Osgood-Schlatter disease or Sinding-Larsen-Johansson syndrome, * Joint effusion in the knee, or presence of redness, swelling, or increased warmth on physical examination, * Serious systemic conditions, including cardiovascular diseases, tumors, gallstones or kidney stones, severe disc or spinal lesions, pacemaker implantation, epilepsy, recent fractures or surgeries, or acute arthritis, * Pregnancy.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| VAS | Change from baseline VAS at the 8th week after the treatment | Pain is the most characteristic symptom in Patellofemoral Pain Syndrome (PFPS). After recording the duration of pain (in months) for each patient, pain intensity was assessed using the Visual Analog Scale (VAS), which is a 10-centimeter (cm) line anchored by 0 (no pain) and 10 (unbearable pain). Patients were asked to rate their pain at rest, during stair ascent/descent, squatting, prolonged sitting, and walking. Crossley et al. have reported that the VAS is a valid, reliable, and responsive tool for assessing pain in individuals with PFPS |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Anterior Knee Pain Scale | Change from baseline AKPS score at the 8th week after the treatment | Subjective symptoms and functional limitations of patients with Patellofemoral Pain Syndrome (PFPS) were evaluated using the Kujala Patellofemoral Scoring System. This scoring system was developed by Kujala et al. in 1993, and it allows for functional assessment of knee pathologies related to the patellofemoral structure. The Kujala Patellofemoral Pain Score consists of 13 subcategories evaluating limping, weight bearing, walking, stair activities, squatting, jumping, prolonged sitting with knees flexed at 90°, running, pain, swelling, abnormal painful patellar movement, thigh atrophy, and loss of flexion. The total score ranges from 0 to 100 points, with 100 indicating the best functional status. |
| Short Form - 36 | Change from baseline SF-36 score at the 8th week after the treatment | The quality of life of all patients will be assessed using the Short Form-36 Health Survey (SF-36). This instrument consists of 36 items and measures eight health domains: Physical functioning (10 items), Social functioning (2 items), Role limitations due to physical problems (4 items), Role limitations due to emotional problems (3 items), Mental health (5 items), Energy/vitality (4 items), Bodily pain (2 items), and General health perception (5 items) |
| Muscle Mass Assessment via Ultrasound | Change from baseline muscle mass assessment at the 8th week after the treatment | Muscle mass measurements of the vastus medialis and gluteus medius muscles will be performed using ultrasound (Clarius™ by Clarius Mobile Health) both before and after treatment. For the vastus medialis, the patient will be positioned supine with the knee in approximately 30 degrees of flexion. The ultrasound probe will be placed on the medial quadriceps region, between the medial border of the patella and the medial femoral condyle. The probe will be angled at approximately 45° to the long axis of the femur, oriented parallel to the muscle fibers. For the gluteus medius, the patient will be positioned in side-lying, with the painful side facing upward. The probe will be placed at the lower half of the distance between a line connecting the anterior superior iliac spine (ASIS) and the posterior superior iliac spine (PSIS) and the greater trochanter. Measurements will be performed by the same evaluator at baseline and at the 8th week following treatment. |
| Change in peak torque at 60°/s (Nm) of the knee muscles measured by isokinetic dynamometer | Change from baseline to Week 8 after treatment | Isokinetic assessment of the symptomatic (painful) knee will be performed using the IsoMed 2000 Isokinetic System. Participants will be seated in an upright position with stabilization of the trunk and lower limbs. Peak Torque (PT, measured in Newton-meters, Nm) represents the maximum torque generated during knee flexion and extension at an angular velocity of 60°/s. Participants will perform four maximal repetitions following three familiarization trials. The change in PT from baseline to week 8 will be used to assess improvement in knee muscle endurance at higher movement speeds. |
| Change in peak torque at 240°/s (Nm) of the knee muscles measured by isokinetic dynamometer | Change from baseline to Week 8 after treatment | Isokinetic assessment of the symptomatic (painful) knee will be performed using the IsoMed 2000 Isokinetic System. Participants will be seated in an upright position with stabilization of the trunk and lower limbs. Peak Torque (PT, measured in Newton-meters, Nm) represents the maximum torque generated during knee flexion and extension at an angular velocity of 240°/s. Participants will perform ten maximal repetitions following three familiarization trials. The change in PT from baseline to week 8 will be used to assess improvement in knee muscle endurance at higher movement speeds. |
| Assessment of the hamstring/quadriceps ratio at 60°/s with an isokinetic dynamometer | Change from baseline VAS at the 8th week after the treatment | The H/Q ratio will be calculated using the peak torque values obtained from the isokinetic tests at 60°/s. Specifically, it is determined by dividing the hamstring peak torque by the quadriceps peak torque measured during the same test session. The H/Q ratio at this slower speed reflects the strength balance between the knee flexors and extensors under controlled movement conditions. A balanced ratio is crucial for joint stability and injury prevention, particularly in patients with knee pain or dysfunction. Testing will be conducted using the IsoMed 2000, with the patient's position and stabilization identical to other isokinetic assessments. |
| Assessment of the hamstring/quadriceps ratio at 240°/s with an isokinetic dynamometer | Change from baseline to week 8 after treatment | The H/Q ratio will also be calculated at 240°/s, based on the peak torque values obtained from the high-velocity isokinetic test. It is computed by dividing the hamstring peak torque by the quadriceps peak torque at this higher angular velocity. The H/Q ratio at 240°/s assesses the dynamic balance and neuromuscular coordination between flexor and extensor muscle groups during rapid movements. Maintaining an appropriate H/Q ratio at faster speeds is considered an important indicator of functional knee stability and injury resilience. All procedures (positioning, stabilization, familiarization, and repetitions) will be performed identically to the other isokinetic test conditions, using the IsoMed 2000 system. |
| Change in Total Work (J) of the Knee Muscles at 60°/s With an Isokinetic Dynamometer | Change from baseline to Week 8 after treatment | Isokinetic assessments of the symptomatic (painful) knee will be performed using the IsoMed 2000 Isokinetic System. Participants will be seated in an upright position, with the chest, waist, and lower limbs secured to ensure proper body stabilization and minimize compensatory movements. To obtain reliable data on muscle performance, testing at an angular velocity of 60°/s will include four consecutive maximal concentric repetitions of knee flexion and extension. Prior to the test, participants will perform three familiarization repetitions at the same velocity to become accustomed to the movement and the device. Total Work (TW), measured in Joules (J), represents the total amount of work performed by the knee flexor and extensor muscles across all repetitions at 60°/s. This parameter reflects overall muscular endurance and energy output of the quadriceps and hamstrings during slower, controlled movements. |
| Change in Total Work (J) of the Knee Muscles at 240°/s With an Isokinetic Dynamometer | Change from baseline to Week 8 after treatment | Isokinetic assessments of the symptomatic (painful) knee will be conducted using the IsoMed 2000 Isokinetic System. Participants will be positioned in an upright seated position, and the chest, waist, and lower limbs will be secured with straps to ensure body stabilization during testing. For this evaluation, an angular velocity of 240°/s will be used, and patients will perform ten consecutive maximal concentric repetitions of knee flexion and extension. Before the test, three familiarization repetitions at the same angular velocity will be completed to ensure accurate and consistent performance. Total Work (TW), expressed in Joules (J), will represent the total energy output of the knee flexor and extensor muscles during all repetitions at 240°/s. This measurement provides information on muscular endurance, power, and performance efficiency of the knee muscles under high-velocity dynamic conditions. |
Countries
Turkey (Türkiye)
Contacts
CONTACTHakan Alkan, Prof Dr
CONTACTMusa Güçlüer, M.D
STUDY_DIRECTORHakan Alkan, Prof Dr
Pamukkale University
Outcome results
None listed