UMIN-CTR Clinical Trial

Public title

Clinical Study Evaluating the Effects of Platelet-Rich Plasma Therapy and Extracorporeal Shock Wave Therapy for Refractory Patellar Tendinopathy

Acronym

PRP-ESWT Patellar Tendinopathy RCT

Scientific Title

Development of Effective Conservative Therapy for Refractory Patellar Tendinopathy: Synergistic Effects of Platelet-Rich Plasma Therapy and Extracorporeal Shock Wave Therapy

Scientific Title:Acronym

PRP-ESWT-PT Study

Region

Japan

Condition

Patellar Tendinopathy (Refractory Cases)

Classification by specialty

Orthopedics

Classification by malignancy

Others

Genomic information

NO

Narrative objectives1

The objective of this study is to prospectively evaluate the effects of platelet-rich plasma (PRP) therapy, extracorporeal shock wave therapy (ESWT), and their combined application on clinical symptoms and tendon structural characteristics in athletes with refractory patellar tendinopathy.

This study aims to compare longitudinal changes in functional recovery and imaging outcomes among treatment groups and to explore whether the combined biological stimulation provided by PRP and mechanical stimulation induced by ESWT may be associated with treatment response and progression toward return to sport within a conservative treatment strategy.

Basic objectives2

Safety,Efficacy

Basic objectives -Others

Trial characteristics_1

Exploratory

Trial characteristics_2

Explanatory

Developmental phase

Not applicable

Primary outcomes

The primary outcome measure is the change in the Victorian Institute of Sport Assessment Patella (VISAP) score from baseline to 24 weeks after completion of treatment.

The VISAP score is a validated patient-reported outcome measure specific to patellar tendinopathy that assesses pain, functional limitations in daily activities, and sport-related performance. Assessments will be conducted at baseline and at 4, 8, 12, and 24 weeks following the final treatment session. The primary endpoint is defined as the change in VISAP score between baseline and 24 weeks.

To provide a comprehensive assessment of functional recovery, additional patient reported outcome measures, including the visual analog scale (VAS) for pain, Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and Lysholm score, will be collected at the same time points and analyzed as supportive measures to the primary outcome.

Key secondary outcomes

Secondary outcome measures include pain intensity, knee functional outcomes, imaging findings, and return-to-sport status.

Pain intensity will be assessed using the visual analog scale (VAS) at baseline and at 4, 8, 12, and 24 weeks following completion of treatment.

Knee functional outcomes will be evaluated using the Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and Lysholm score at the same assessment time points to analyze longitudinal functional changes.

Structural tendon changes will be assessed using magnetic resonance imaging (MRI) with short tau inversion recovery (STIR) sequences, measuring lesion length on sagittal images and lesion width and thickness on axial images. Ultrasonographic evaluation will include measurement of hypoechoic lesion area and assessment of intratendinous vascularity using color Doppler imaging. Imaging assessments will be performed at baseline, 12 weeks, and 24 weeks.

Return-to-sport outcomes will be evaluated at the final 6-month follow-up using a self-reported questionnaire assessing return to sport participation, return to pre-injury performance level, presence of pain during sport activity, and recurrence.

Study type

Interventional

Basic design

Parallel

Randomization

Randomized

Randomization unit

Individual

Blinding

Open -no one is blinded

Control

Active

Stratification

NO

Dynamic allocation

NO

Institution consideration

Institution is not considered as adjustment factor.

Blocking

NO

Concealment

Central registration

No. of arms

3

Purpose of intervention

Treatment

Type of intervention

Device,equipment

Maneuver

Interventions/Control_1

Extracorporeal shock wave therapy ESWT was administered using a diffuse type shock wave device PHYSIO SHOCKMASTER Sakai Medical Japan.

Shock waves were delivered to the affected patellar tendon at 2500 shocks per session with a frequency of 8 Hz and pressure of 2.4 to 4.0 bar.

Treatment was performed once weekly for three sessions over 3 weeks.

All participants additionally underwent a standardized eccentric rehabilitation program throughout the intervention and follow up period.

The total observation period was 24 weeks.

Interventions/Control_2

Platelet-rich plasma (PRP) therapy was performed using autologous blood processed with the ACP double-syringe system (Arthrex Japan).

PRP was injected into the affected patellar tendon under ultrasound guidance.
PRP injections were administered three times at 2 week intervals over a 6 week treatment period.

All participants performed a standardized eccentric rehabilitation program during the intervention and follow-up period.
The total follow-up duration was 24 weeks.

Interventions/Control_3

Combined therapy consisting of platelet rich plasma PRP injection and extracorporeal shock wave therapy ESWT was administered.

ESWT was delivered using a diffuse type shock wave device at 2500 shocks per session with a frequency of 8 Hz and pressure of 2.4 to 4.0 bar once weekly for three sessions.

PRP was prepared using the ACP double syringe system and injected into the affected tendon under ultrasound guidance at 2 week intervals for a total of three injections.

Both interventions were conducted within the same treatment period and all participants underwent a standardized eccentric rehabilitation program.

The total observation period was 24 weeks.

Interventions/Control_4

Interventions/Control_5

Interventions/Control_6

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

18

years-old

<=

Age-upper limit

50

years-old

>=

Gender

Male and Female

Key inclusion criteria

Participants eligible for inclusion must meet all of the following criteria:

Competitive athletes aged 18 to 50 years

Diagnosis of chronic patellar tendinopathy with symptoms persisting for 3 months or longer and refractory to prior conservative treatment, including physiotherapy or exercise based rehabilitation

Presence of localized tenderness at the inferior pole of the patella or pain during active knee extension

At least one imaging abnormality consistent with chronic patellar tendinopathy identified on MRI or ultrasonography, including tendon thickening, hypoechoic regions, or intratendinous hyperintensity on STIR sequences

Ability to provide written informed consent after receiving a full explanation of the study

Key exclusion criteria

Participants meeting any of the following criteria will be excluded from the study:

Presence of systemic disease that may affect tendon healing, including diabetes mellitus, rheumatoid arthritis, active infection, coagulopathy, immunosuppression, hemoglobin level less than 11 g per dL, or platelet count less than 150000 per mm3

Current treatment with antiplatelet agents or anticoagulant therapy

History of intra articular steroid injection or knee surgery within the past 3 months

Use of nonsteroidal anti inflammatory drugs within 5 days prior to treatment

Pregnancy

Malignant tumor

Known allergy to local anesthetics

Presence of other knee disorders that may influence clinical outcomes

Target sample size

10

Name of lead principal investigator

1st name	Yuki
Middle name
Last name	Shimizu

Organization

Nippon Sport Science University

Division name

Faculty of Health and Medical Sciences

Zip code

227-0033

Address

1221-1 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa 227-0033, Japan Yokohama Kenshidai Campus

TEL

+81-3-5706-0900

Email

shimizu.y@nittai.ac.jp

Name of contact person

1st name	YUKI
Middle name
Last name	SHIMIZU

Organization

Nippon Sport Science University

Division name

Faculty of Health and Medical Sciences

Zip code

227-0033

Address

1221-1 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa 227-0033, Japan Yokohama Kenshidai Campus

TEL

+81-3-5706-0900

Homepage URL

Email

shimizu.y@nittai.ac.jp

Institute

Nippon Sport Science University

Institute

Department

Personal name

YUKI SHIMIZU

Organization

Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan

Organization

Division

Category of Funding Organization

Japanese Governmental office

Nationality of Funding Organization

Co-sponsor

Name of secondary funder(s)

Organization

Research Ethics Committee of Nippon Sport Science University

Address

7-1-1 Fukasawa, Setagaya-ku, Tokyo 158-8508, Japan Nippon Sport Science University

Tel

+81-3-5706-0900

Email

kaken@nittai.ac.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

日本体育大学クリニック（東京都）

Date of disclosure of the study information

2026

Year

02

Month

28

Day

URL releasing protocol

https://mol.medicalonline.jp/archive/search?jo=fj2ortho&ye=2024&vo=98&issue=8

Publication of results

Published

URL related to results and publications

https://mol.medicalonline.jp/archive/search?jo=fj2ortho&ye=2024&vo=98&issue

Number of participants that the trial has enrolled

10

Results

Ten athletes with refractory patellar tendinopathy were treated with PRP, ESWT, or combined PRP plus ESWT therapy. Pain (VAS) and functional scores (VISA-P, IKDC, KOOS Total) improved over time in all groups, with greater improvement observed in the combined therapy group. MRI and ultrasound findings demonstrated reduction of intratendinous lesions. All participants returned to sport, and no serious adverse events were observed.

Results date posted

2026

Year

02

Month

27

Day

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

A total of 10 athletes diagnosed with refractory patellar tendinopathy were enrolled. All participants had symptoms persisting for more than 3 months despite conservative treatment. The mean age was 19.5 years range 17-21 years including 9 males and 1 female. All participants intended to continue or return to sports. At baseline the mean VISA-P score was 45.9 points and the mean VAS during sports activity was 60.3 indicating substantial pain and functional limitation.

Participant flow

A total of 10 eligible participants were enrolled in this study. All participants received combined treatment consisting of platelet-rich plasma (PRP) injection and extracorporeal shock wave therapy (ESWT).
No participants were lost to follow-up during the study period, and all 10 participants completed the 24-week follow-up assessment. All enrolled participants were included in the final analysis.

Adverse events

No serious adverse events were observed during the study period. Transient local pain and mild swelling following PRP injection were observed in several participants; however, these symptoms resolved spontaneously without additional treatment. No infections, tendon rupture, or neurovascular complications were reported.

Outcome measures

The primary outcome measure was the change in the Victorian Institute of Sport Assessment Patella VISA P score. Secondary outcome measures included pain intensity assessed using the Visual Analog Scale VAS and ultrasonographic evaluation of hypoechoic area and intratendinous lesion length. Assessments were performed at baseline and at 4 12 and 24 weeks after treatment.

Plan to share IPD

There are no plans to make individual participant data (IPD) publicly available.

IPD sharing Plan description

Individual participant data collected in this study will be anonymized and securely managed.
However, due to considerations regarding participant privacy and data protection, there are no plans to share the data with external researchers or make them publicly available.

Recruitment status

Completed

Date of protocol fixation

2021

Year

04

Month

10

Day

Date of IRB

2021

Year

04

Month

16

Day

Anticipated trial start date

2021

Year

06

Month

02

Day

Last follow-up date

2026

Year

03

Month

01

Day

Date of closure to data entry

2026

Year

03

Month

04

Day

Date trial data considered complete

2026

Year

03

Month

07

Day

Date analysis concluded

2026

Year

03

Month

10

Day

Other related information

The results of this study were presented as a poster at the 97th Annual Meeting of the Japanese Orthopaedic Association in 2024. This clinical study investigated the therapeutic effects of platelet rich plasma and extracorporeal shock wave therapy for refractory patellar tendinopathy.

Registered date

2026

Year

02

Month

27

Day

Last modified on

2026

Year

02

Month

27

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000069535