Trial Outcomes & Findings for Platelet-Rich Plasma (PRP) Injection for the Treatment of Chronic Patellar Tendinopathy (NCT NCT01843504)
NCT ID: NCT01843504
Last Updated: 2026-07-22
Results Overview
Participants will complete outcome questionnaires at weeks 0, 4, 8, 12, 16, and 32 weeks. The results will evaluate pain- and function-dependent, knee-specific quality of life, as assessed by composite scores on the Knee Injection Questionnaire. The total possible range of scores is 0-100 with higher scores indicating improved well being and ability to activities.
COMPLETED
PHASE2
29 participants
0, 4, 8, 12, 16, and 32 weeks
2026-07-22
Participant Flow
Participants were recruited from Wisconsin Institute for Medical Research (WIMR) from February 2014 to August 2022.
Participant milestones
| Measure |
Platelet Rich Plasma (PRP)
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
Platelet rich plasma: A blood draw of 15 mL of the subject's own blood will be performed. The study coordinator will then place the sample in the Platelet Separator System (a centrifuge) and spin the blood sample in using a two-stage spinning: the 1st separates red blood cells from platelets, and the 2nd concentrates the platelets. This will be spun by centrifuge to yield 6 mL of concentrated autologous platelet. Under continuous ultrasound evaluation, 1.0-2.0 mL of the prepared PRP will be injected onto the origin of the patella tendon itself will be peppered along a short segment of the tendon into the areas of palpated tenderness and US-documented pathology.
|
Normal Saline
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
Saline: A blood draw of 15 mL of the subject's own blood will be performed to maintain blinding. Under continuous ultrasound evaluation, 1.0-2.0 mL of the saline solution will be injected onto the origin of the patella tendon itself will be peppered along a short segment of the tendon into the areas of palpated tenderness and US-documented pathology.
|
|---|---|---|
|
Overall Study
STARTED
|
15
|
14
|
|
Overall Study
Tendinopathy of Left Knee
|
9
|
5
|
|
Overall Study
Tendinopathy of Right Knee
|
4
|
7
|
|
Overall Study
Bilateral Tendinopathy
|
2
|
2
|
|
Overall Study
Participants With 32 Week Survey Data
|
12
|
13
|
|
Overall Study
COMPLETED
|
12
|
13
|
|
Overall Study
NOT COMPLETED
|
3
|
1
|
Reasons for withdrawal
| Measure |
Platelet Rich Plasma (PRP)
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
Platelet rich plasma: A blood draw of 15 mL of the subject's own blood will be performed. The study coordinator will then place the sample in the Platelet Separator System (a centrifuge) and spin the blood sample in using a two-stage spinning: the 1st separates red blood cells from platelets, and the 2nd concentrates the platelets. This will be spun by centrifuge to yield 6 mL of concentrated autologous platelet. Under continuous ultrasound evaluation, 1.0-2.0 mL of the prepared PRP will be injected onto the origin of the patella tendon itself will be peppered along a short segment of the tendon into the areas of palpated tenderness and US-documented pathology.
|
Normal Saline
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
Saline: A blood draw of 15 mL of the subject's own blood will be performed to maintain blinding. Under continuous ultrasound evaluation, 1.0-2.0 mL of the saline solution will be injected onto the origin of the patella tendon itself will be peppered along a short segment of the tendon into the areas of palpated tenderness and US-documented pathology.
|
|---|---|---|
|
Overall Study
Lost to Follow-up
|
3
|
1
|
Baseline Characteristics
Platelet-Rich Plasma (PRP) Injection for the Treatment of Chronic Patellar Tendinopathy
Baseline characteristics by cohort
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Total
n=29 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Customized
10 to 19 years old
|
6 Participants
n=9 Participants
|
3 Participants
n=27 Participants
|
9 Participants
n=267 Participants
|
|
Age, Customized
20 to 29 years old
|
2 Participants
n=9 Participants
|
4 Participants
n=27 Participants
|
6 Participants
n=267 Participants
|
|
Age, Customized
30 to 39 years old
|
3 Participants
n=9 Participants
|
4 Participants
n=27 Participants
|
7 Participants
n=267 Participants
|
|
Age, Customized
40 to 49 years old
|
1 Participants
n=9 Participants
|
3 Participants
n=27 Participants
|
4 Participants
n=267 Participants
|
|
Age, Customized
50 to 59 years old
|
3 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
3 Participants
n=267 Participants
|
|
Sex: Female, Male
Female
|
1 Participants
n=9 Participants
|
1 Participants
n=27 Participants
|
2 Participants
n=267 Participants
|
|
Sex: Female, Male
Male
|
14 Participants
n=9 Participants
|
13 Participants
n=27 Participants
|
27 Participants
n=267 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
15 Participants
n=9 Participants
|
14 Participants
n=27 Participants
|
29 Participants
n=267 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=9 Participants
|
1 Participants
n=27 Participants
|
1 Participants
n=267 Participants
|
|
Race (NIH/OMB)
Asian
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Race (NIH/OMB)
Black or African American
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Race (NIH/OMB)
White
|
14 Participants
n=9 Participants
|
13 Participants
n=27 Participants
|
27 Participants
n=267 Participants
|
|
Race (NIH/OMB)
More than one race
|
0 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
0 Participants
n=267 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
1 Participants
n=9 Participants
|
0 Participants
n=27 Participants
|
1 Participants
n=267 Participants
|
|
Region of Enrollment
United States
|
15 participants
n=9 Participants
|
14 participants
n=27 Participants
|
29 participants
n=267 Participants
|
PRIMARY outcome
Timeframe: baseline and 32 weeksPopulation: Participants were lost to follow-up
Participants will complete outcome questionnaires at baseline and 32 weeks. The results will evaluate pain- and function-dependent, knee-specific quality of life, as assessed by composite scores on the validated Victorian Institute of Sport Assessment-Patellar (VISAP). The total possible range of scores is 0-100 with higher scores indicating fewer symptoms and higher function.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Victorian Institute of Sport Assessment-Patellar (VISAP) Score
baseline
|
47.9 score on a scale
Standard Deviation 17.4
|
36.4 score on a scale
Standard Deviation 17.8
|
—
|
—
|
|
Victorian Institute of Sport Assessment-Patellar (VISAP) Score
week 32
|
64.4 score on a scale
Standard Deviation 21.9
|
52.2 score on a scale
Standard Deviation 25.5
|
—
|
—
|
PRIMARY outcome
Timeframe: baseline and 32 weeksPopulation: Participants were lost to follow-up
Participants will complete outcome questionnaires at baseline and 32 weeks. The results will evaluate pain- and function-dependent, knee-specific quality of life, as assessed by composite scores on the International Knee Documentation Committee (IKDC). The total possible range of scores is 0-100 with higher scores indicating higher function and lower symptoms.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
International Knee Documentation Committee (IKDC) Score
baseline
|
55.7 score on a scale
Standard Deviation 9.8
|
48.8 score on a scale
Standard Deviation 13.1
|
—
|
—
|
|
International Knee Documentation Committee (IKDC) Score
week 32
|
60.8 score on a scale
Standard Deviation 12.4
|
52.1 score on a scale
Standard Deviation 20.9
|
—
|
—
|
PRIMARY outcome
Timeframe: 0, 4, 8, 12, 16, and 32 weeksPopulation: Participants were lost to follow-up
Participants will complete outcome questionnaires at weeks 0, 4, 8, 12, 16, and 32 weeks. The results will evaluate pain- and function-dependent, knee-specific quality of life, as assessed by composite scores on the Knee Injection Questionnaire. The total possible range of scores is 0-100 with higher scores indicating improved well being and ability to activities.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Knee Injection Questionnaire Score
week 4
|
90.9 score on a scale
Standard Deviation 39.4
|
93.6 score on a scale
Standard Deviation 30.2
|
—
|
—
|
|
Knee Injection Questionnaire Score
week 8
|
84.8 score on a scale
Standard Deviation 48.4
|
96.8 score on a scale
Standard Deviation 29.4
|
—
|
—
|
|
Knee Injection Questionnaire Score
week 12
|
97.9 score on a scale
Standard Deviation 44.3
|
95.7 score on a scale
Standard Deviation 38.4
|
—
|
—
|
|
Knee Injection Questionnaire Score
baseline
|
84.8 score on a scale
Standard Deviation 14.9
|
71.6 score on a scale
Standard Deviation 19.6
|
—
|
—
|
|
Knee Injection Questionnaire Score
week 16
|
96.1 score on a scale
Standard Deviation 43.1
|
99.4 score on a scale
Standard Deviation 40.5
|
—
|
—
|
|
Knee Injection Questionnaire Score
week 32
|
90.1 score on a scale
Standard Deviation 50.8
|
100.0 score on a scale
Standard Deviation 39.3
|
—
|
—
|
SECONDARY outcome
Timeframe: baseline to 32 weeksPopulation: Participant counts vary from baseline to 32 weeks because participants did not provide data or image was unreadable. At baseline, one participant in in the PRP group and one participant in the Normal Saline Group had insufficient imaging to measure thickness.
Ultrasound (US) changes of several pathologic features of PT will be evaluated using US imaging of the patellar tendon at 32 weeks compared to baseline imaging. Conventional ultrasound will be done to assess patellar tendon thickness (contralateral comparison). Data are reported by treatment knee vs contralateral knee. In cases where tendinopathy was bilateral, the thicker tendon at baseline was considered the worse involved knee / treatment knee.
Outcome measures
| Measure |
Platelet Rich Plasma
n=14 knees
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 knees
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
n=13 knees
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
n=13 knees
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Thickness of Patellar Tendon Compared to Contralateral
baseline
|
7.21 millimeters
Standard Deviation 2.22
|
5.68 millimeters
Standard Deviation 1.36
|
6.89 millimeters
Standard Deviation 1.51
|
5.23 millimeters
Standard Deviation 1.11
|
|
Thickness of Patellar Tendon Compared to Contralateral
32 weeks
|
7.72 millimeters
Standard Deviation 2.39
|
5.83 millimeters
Standard Deviation 1.23
|
7.65 millimeters
Standard Deviation 1.62
|
5.21 millimeters
Standard Deviation 0.86
|
SECONDARY outcome
Timeframe: baseline to 32 weeksPopulation: Participant counts vary from baseline to 32 weeks because participants did not provide data or image was unreadable.
Ultrasound (US) changes of several pathologic features of PT will be evaluated using US imaging of the patellar tendon at 32 weeks compared to baseline imaging. Conventional ultrasound will be done to assess patellar tendon neovascularity. The grading scales for neovascularity (abnormal formation of new blood vessels) is 0-3, with 3 being more severe. Data reported are for symptomatic limb or limb with the thickest tendon in bilateral cases.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Neovascularity of Patellar Tendon
baseline
|
0.93 score on a scale
Standard Deviation 1.12
|
1.29 score on a scale
Standard Deviation 1.10
|
—
|
—
|
|
Neovascularity of Patellar Tendon
32 weeks
|
1.31 score on a scale
Standard Deviation 1.14
|
1.00 score on a scale
Standard Deviation 1.04
|
—
|
—
|
SECONDARY outcome
Timeframe: baseline to 32 weeksPopulation: Participant counts vary from baseline to 32 weeks because participants did not provide data or image was unreadable.
Ultrasound (US) changes of several pathologic features of PT will be evaluated using US imaging of the patellar tendon at 32 weeks compared to baseline imaging. Conventional ultrasound will be done to assess patellar hypoechogenicity. The grading scale for hypoechogenicity (area on an image that appears darker gray than surrounding image, reflecting fewer sound waves) is 0-3, with 3 being more severe. Data reported are for symptomatic limb or limb with the thickest tendon in bilateral cases.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=14 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Hypoechogenicity of Patellar Tendon
baseline
|
1.73 score on a scale
Standard Deviation 0.93
|
1.86 score on a scale
Standard Deviation 0.83
|
—
|
—
|
|
Hypoechogenicity of Patellar Tendon
32 weeks
|
1.85 score on a scale
Standard Deviation 0.77
|
2.27 score on a scale
Standard Deviation 0.62
|
—
|
—
|
SECONDARY outcome
Timeframe: baseline to 32 weeksPopulation: Participant counts vary from baseline to 32 weeks because participants did not provide data or image was unreadable. One participant in the Normal Saline group had insufficient imaging to measure stiffness at baseline.
Acoustoelastography (AE) will be done to measure stiffness changes of the patellar tendon. Stiffness is measured in meters per second and higher values indicate greater stiffness of patellar tendons. Data reported are for symptomatic limb or limb with the thickest tendon in bilateral cases.
Outcome measures
| Measure |
Platelet Rich Plasma
n=15 Participants
Participants in Group 1 (PRP) will receive a single US-guided injection of 5 mL autologous platelet-rich plasma at week 0 (baseline).
|
Normal Saline
n=13 Participants
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Knee With (Worse) Tendinopathy
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
Normal Saline - Contralateral Knee
Participants in Group 2 (saline control) will receive a single injection of 5 mL 0.9% normal saline at week 0.
|
|---|---|---|---|---|
|
Stiffness of Patellar Tendon
baseline
|
9.13 meters per second
Standard Deviation 1.84
|
8.26 meters per second
Standard Deviation 2.00
|
—
|
—
|
|
Stiffness of Patellar Tendon
32 weeks
|
8.97 meters per second
Standard Deviation 2.14
|
9.07 meters per second
Standard Deviation 2.30
|
—
|
—
|
OTHER_PRE_SPECIFIED outcome
Timeframe: up to 32 weeksOutcome measures will be compared for satisfaction with PRP therapy as assessed by the treatment satisfaction survey score at 32 weeks post-treatment. This survey is a 5-item survey that assesses * severity of symptoms (0 no symptoms to 6 worst symptoms) * level of difficulty in using the knee, if any, (1 mild to 4 unable to use knee) * change in knee symptoms since treatment (-3 very much worse to 0 no change to 3 very much improved) * physical ease, comfort, convenience, and effectiveness satisfaction with PRP therapy (each from -3 extremely dissatisfied to 0 neutral to 3 extremely satisfied), and * temporary pain, bruising, swelling, bleeding, or other side effects (from 5 all of the time to 0 none of the time)
Outcome measures
Outcome data not reported
Adverse Events
Platelet Rich Plasma
Normal Saline
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
John Wilson, MD, MS
UW School of Medicine and Public Health
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place