Extracorporeal Shock Wave Therapy in Patellofemoral Pain Syndrome

Effectiveness of Extracorporeal Shock Wave Therapy in Patellofemoral Pain Syndrome: A Randomized Controlled Trial

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 Overview

• Status: Completed
• Conditions: Patellofemoral Pain Syndrome
• Intervention / Treatment: Behavioral: Home-based Exercise Program; Device: Radial Extracorporeal Shock Wave Therapy (ESWT)

• Study Type: Interventional
• Enrollment (Actual): 36
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Nilüfer
    • Bursa, Nilüfer, Turkey (Türkiye), 16059
      • Bursa Uludağ University Sports Medicine Clinic

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Exercise; Participants performed a structured home-based exercise program targeting hip and knee musculature. The program included warm-up, stretching, and progressive strengthening exercises for the quadriceps, hip abductors, hip external rotators, and core stability muscles. Participants were instructed to complete the program at least three times per week for 4 weeks. Exercise technique and progression guidelines were explained in person, and adherence was monitored using weekly exercise diaries and telephone follow-up.	Behavioral: Home-based Exercise Program; 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.
Experimental: ESWT; Participants received five sessions of radial extracorporeal shock wave therapy (ESWT) administered at 5-day intervals. Treatment was delivered using the Chattanooga Intelect® RPW device with 2000 pulses per session at 1.8-2.0 bar pressure and 8 Hz frequency. Stimulation was applied to the peripatellar soft tissues, including the medial and lateral patellofemoral retinaculum and the infrapatellar fat pad, while avoiding direct application over the patellar tendon. Pressure was progressively increased across sessions based on tolerance.	Device: Radial Extracorporeal Shock Wave Therapy (ESWT); 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.
Experimental: Exercise + ESWT; Participants performed the same home-based strengthening program as the Exercise group (hip and knee strengthening, ≥3 sessions/week for 4 weeks). In addition, they received five sessions of radial extracorporeal shock wave therapy (2000 pulses; 1.8-2.0 bar; 8 Hz) at 5-day intervals applied to the peripatellar soft tissues while avoiding the patellar tendon.	Behavioral: Home-based Exercise Program; 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.; Device: Radial Extracorporeal Shock Wave Therapy (ESWT); 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Baseline, Week 1, Week 8

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	Baseline, Week 1, Week 8

Collaborators and Investigators

• Sponsor: Uğur Can Yalaki

Study record dates

Study Major Dates

• Study Start (Actual): January 4, 2021
• Primary Completion (Actual): July 5, 2021
• Study Completion (Actual): September 6, 2021

Study Registration Dates

• First Submitted: November 26, 2025
• First Submitted That Met QC Criteria: November 26, 2025
• First Posted (Estimated): December 9, 2025

Study Record Updates

• Last Update Posted (Estimated): December 9, 2025
• Last Update Submitted That Met QC Criteria: November 26, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: exercise therapy; patellofemoral pain syndrome; extracorporeal shock-wave therapy
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Joint Diseases; Patellofemoral Pain Syndrome
• Other Study ID Numbers: PFPS-ESWT-2021

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No