Chronic patellar tendinopathy is highly prevalent among youth, amateur, and elite athletes, with rates reaching 30-40% in high-performance populations. Among current conservative treatments, platelet-rich plasma (PRP) injections and extracorporeal shockwave therapy (ESWT) have demonstrated promising clinical outcomes. However, high-quality randomized controlled trials comparing ESWT alone versus ESWT combined with different injection therapies remain lacking. Objective: To compare the clinical effectiveness of ESWT alone, ESWT combined with hyaluronic acid (HA), and ESWT combined with PRP in athletes with chronic patellar tendinopathy. Methods: A three-arm, single-blind randomized controlled trial will be conducted. Athletes participating in sports with repetitive jumping or explosive lower-limb loading will be enrolled and stratified by sport type. Inclusion criteria include typical anterior knee pain, a positive decline squat test, and ultrasonographic evidence of tendon thickening or hypoechoic changes. Calcified tendinopathy will be excluded. Outcomes will be assessed at 1, 3, 6, 9, and 12 months, including VAS, VISA-P, SPORTS scale, sport-specific performance tests (vertical jump, single-leg hop, agility tests), and return-to-play (RTP) time. Expected Impact: This study aims to address three key clinical questions: 1. Is ESWT alone adequate as an initial treatment for chronic patellar tendinopathy in athletes? 2. If adjunctive injection is needed, does HA or PRP provide superior short- and long-term outcomes? 3. Which treatment strategy results in the fastest safe return to sport? The findings of this trial will provide evidence-based guidance for clinicians and contribute to the development of more precise treatment algorithms, ultimately enhancing performance longevity and protecting the careers of high-level athletes.
1\. Research Objective: Chronic patellar tendinitis is a common and highly recurrent sports injury among advanced athletes. Currently, various non-surgical treatments, such as ESWT and PRP injections, are commonly used clinically. However, high-quality randomized controlled trials are lacking regarding whether combined injection therapy is necessary and whether ESWT combined with HA or PRP is more suitable for athletes. This study aims to comprehensively compare the efficacy of ESWT alone versus ESWT combined with either injection therapy through three parallel, stratified, randomized, single-blind clinical trials, providing clinically applicable treatment guidelines. The objectives of this study are: 1. To compare the clinical efficacy differences between ESWT alone and ESWT combined with HA/PRP. 2. To compare the efficacy differences between ESWT combined with HA and ESWT combined with PRP at different time points. 3. To clarify the impact of different treatment strategies on athletes' return to play (RTP). 2\. Research Hypotheses: 1. ESWT combined with either HA or PRP will be superior to ESWT alone in terms of pain relief (VAS). 2. ESWT combined with HA will be more effective than ESWT combined with PRP in short-term pain relief. (3) ESWT combined with PRP is superior to ESWT alone or ESWT+HA in terms of mid- to long-term functional improvement, motor performance, and specific tests. 3\. Study Endpoints 1. Primary: Pain improvement at 3 months post-treatment (VAS change from baseline to 3 months) 2. Secondary: Clinical Symptoms and Function Scales: VAS, VISA-P, SPORTS scale Return to Play (RTP): RTP duration (days), RTP level (complete, playable, with load limitations), relapse rate (12 months) 3. Ultrasound indicators: thickness and elasticity, size of hypoechoic area, Doppler (neovascularity) 4\. Study Design This study is a prospective clinical trial with three parallel, stratified, randomized, single-blind (subject-blind) groups. The study aimed to compare the clinical efficacy, functional recovery, and return to play (RTP) differences between: 1. ESWT alone (ESWT + Placebo injection, microdose normal saline) 2. ESWT combined with hyaluronic acid injection (ESWT+HA) 3. ESWT combined with high-concentration platelet-plasma injection (ESWT+PRP) in athletes with chronic patellar tendinitis. The study procedure employed a standardized intervention protocol, uniform ultrasound diagnosis and injection site, and fixed ESWT energy settings. All follow-up tests and questionnaire completion were conducted by independent assessors unaware of their assigned groups.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
45
Shockwave therapy is a treatment method that uses high-energy sound waves delivered to body tissues. Through shockwave stimulation of specific frequencies and energy levels, it acts on areas of pain or dysfunction, promoting tissue repair. It is commonly used for chronic musculoskeletal discomfort and sports injury-related problems. In this program, shockwave therapy is the basic treatment, and each experimental group will receiveExtracorporeal Shock Wave Therapy (
Hyaluronic acid is primarily used in medicine as an intra-articular injection to relieve pain from osteoarthritis and lubricate joints.
PRP (Platelet-Rich Plasma) Brief Introduction and Definition: Concentrated blood plasma rich in platelets and growth factors, extracted from the patient's own blood. Uses: Belonging to regenerative medicine and proliferative therapy, it is commonly used to help repair soft tissues such as muscles, tendons, ligaments, and joints. Principle: Utilizing growth factors from the patient's own blood, it accelerates the healing and regeneration of body tissues.
Normal saline is a 0.9% sterile aqueous solution of sodium chloride. Its osmotic pressure is similar to that of human blood plasma, and it is widely used in medical and daily care. In this study, it was used as a placebo.
Kaohsiung Chang Gung Memorial Hospital
Kaohsiung City, Kaohsiung, Taiwan
Visual Analogue Scale(VAS)
VAS（Visual Analogue Scale）：Ask the patient to mark the degree of their pain on a 10 cm line, from "no pain" on the far left to "unbearable pain" on the far right. The "Numerical Rating Scale" uses a numerical concept of 0-10 points to express the degree of pain, from no pain (0 points) to very painful (10 points).
Time frame: From enrollment to the end of treatment at 48 weeks
The Victorian Institute of Sport Assessment (VISA-) Patella (P) Questionnaire
VISA-P: A professional self-assessment tool used to evaluate the severity and treatment effectiveness of patellar tendinopathy. The maximum score is 100 points. A higher score indicates milder symptoms and better function; a lower score indicates a more severe condition. Question Structure: Contains 8 questions. First 6 questions: Assess the degree of pain and functional limitations in specific daily activities (such as sitting, squatting, climbing stairs, hopping on one leg, etc.). Last 2 questions: Assess the level of motor engagement, the ability to train, and the duration of training.
Time frame: From enrollment to the end of treatment at 48 weeks
SPORTS score (Subjective Patient Outcome for Return to Sports)
In the fields of sports medicine and orthopedics, the SPORTS scale (Subjective Patient Outcome for Return to Sports score) is a core assessment scale specifically designed to evaluate an athlete's ability to return to sports (RTS) after experiencing a sports injury (such as anterior cruciate ligament rupture, shoulder instability, elbow injury, etc.) and undergoing surgery or treatment. It comprises three independent conceptual constructs: 1) the ability to return to pre-injury intensity and training levels; 2) the ability to achieve the same level of athletic performance; and 3) the ability to achieve 1) and 2 above without pain or with pain relief. This tool uses a 10-point scale, where 0 indicates the patient cannot return to their pre-injury level of athletic performance, and 10 indicates the patient can perform the same sport with the same effort and performance level as before the injury without pain
Time frame: From enrollment to the end of treatment at 48 weeks
Return to Play (RTP)
Return to Play (RTP) refers to the complete decision-making process by which athletes safely and gradually return to training and competition after injury or surgery, through medical treatment, physical therapy, and scientific training. RTP comprises three main phases: Return to Participation: Begin non-contact, basic physical and technical rehabilitation training. Return to Sport: Participate in sport-specific movements, simulated competition, and team training. Return to Performance: Recover to the pre-injury competitive level and peak performance.
Time frame: From enrollment to the end of treatment at 48 weeks
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