Extracorporeal Shock Wave Therapy in Patellofemoral Pain Syndrome

Uğur Can Yalaki36 enrolled

Overview

Patellofemoral pain syndrome (PFPS) is a common cause of anterior knee pain and functional limitations in physically active individuals. Exercise-based rehabilitation is considered the primary treatment approach, yet a proportion of patients experience persistent symptoms. Extracorporeal shock wave therapy (ESWT) is a non-invasive modality that may reduce pain through neuromodulation and tissue-level biological responses. This randomized controlled trial evaluated the effects of ESWT on knee pain and function in adults with PFPS. Thirty-six participants aged 18-45 years were randomly assigned to one of three groups: Exercise, Exercise plus ESWT, or ESWT alone. The exercise program consisted of home-based hip and knee strengthening performed at least three times per week for four weeks. ESWT was administered as five radial shock wave sessions at five-day intervals around the peripatellar soft tissues. Outcomes included worst knee pain measured by the Visual Analogue Scale and functional status measured by the Kujala Patellofemoral Score at baseline, week 1, and week 8. All groups demonstrated significant improvements over time, with no significant differences between groups. The treatment was well tolerated. This trial was retrospectively registered after patient enrollment was completed.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Patellofemoral Pain Syndrome

Interventions

Home-based Exercise ProgramBEHAVIORAL

A structured home-based exercise program targeting hip and knee musculature. The program included warm-up, stretching, and progressive strengthening for the quadriceps, hip abductors, hip external rotators, and core stability muscles. Participants were instructed to perform the program at least three times per week for 4 weeks. Exercise progression and technique were explained individually. Adherence was monitored with weekly exercise diaries and telephone follow-up.

Radial Extracorporeal Shock Wave Therapy (ESWT)DEVICE

Five sessions of radial extracorporeal shock wave therapy delivered at 5-day intervals using the Chattanooga Intelect® RPW device. Each session consisted of 2000 pulses at 1.8-2.0 bar pressure and 8 Hz frequency. Treatment was applied to the peripatellar soft tissues (medial and lateral retinaculum and infrapatellar fat pad), while avoiding direct application over the patellar tendon. Pressure was adjusted based on participant tolerance.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 45 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Age 18 to 45 years. * Clinical diagnosis of patellofemoral pain syndrome (PFPS) characterized by anterior or retropatellar knee pain lasting at least 8 weeks. * Pain provoked during at least two of the following activities: running, jumping, squatting, stair climbing, or prolonged sitting. * Worst knee pain score of ≥3 on the Visual Analog Scale (0-10). * Ability to understand and follow the exercise program and assessment procedures. * Provided written informed consent. Exclusion Criteria: * Evidence of intra-articular knee pathology other than grade 1-2 meniscal changes or grade 1 chondromalacia patella on MRI. * Clinical signs of patellar instability. * Localized tenderness indicating alternative diagnoses (e.g., patellar tendinopathy, iliotibial band syndrome, pes anserine bursitis). * History of knee surgery on the affected side. * Intra-articular injections (e.g., corticosteroids, hyaluronic acid, PRP) within the past 6 months. * Neurological or rheumatological disorders affecting the lower extremity. * Active infection, open wound, tumor, or severe dermatological condition at or near the ESWT application site. * Pregnancy.

Outcomes

Primary Outcomes

Visual Analogue Scale, 0-10

The Visual Analog Scale (VAS) was used to assess the worst knee pain experienced in the previous week during daily or functional activities. Participants rated their pain on a 0-10 scale, where 0 represents no pain and 10 represents the worst imaginable pain. Pain intensity was recorded at baseline prior to intervention, at one week, and at eight weeks after the treatment to evaluate short- and mid-term treatment effects.

Time frame: Baseline, Week 1, Week 8

Secondary Outcomes

Kujala Patellofemoral Score

The Kujala Anterior Knee Pain Scale was used to evaluate knee-specific functional status. This validated questionnaire consists of 13 items assessing pain, functional limitations, and activities such as running, stair climbing, prolonged sitting, and squatting. Total scores range from 0 to 100, with higher scores indicating better function. Assessments were completed at baseline, at one week, and at eight weeks after the treatment to determine functional improvement over time.