Baseline characteristics of the progressive tendon-loading exercise (PTLE) and eccentric exercise therapy (EET) groups*
| Characteristics | PTLE group (n=38) | EET group (n=38) |
| Age, mean (SD), years | 24 (3.5) | 24 (4.2) |
| Sex, male | 31 (82) | 27 (71) |
| BMI, mean (SD) | 23.8 (2.5) | 24.1 (3.2) |
| Symptom duration, median (IQR), weeks | 119 (64-273) | 78 (40-169) |
| VISA-P score, mean (SD) | 55 (13.1) | 56 (13.2) |
| CSAS, prior to onset of PT | ||
| Level I (4–7 days/week) | ||
| 100 | 10 (26) | 7 (18) |
| 95 | 0 (0) | 0 (0) |
| 90 | 0 (0) | 0 (0) |
| Level II (1–3 days/week) | ||
| 85 | 23 (61) | 27 (71) |
| 80 | 5 (13) | 4 (11) |
| Sports participation in desired sport at the time of study commencement, n (%) | ||
| Equal | 10 (26) | 9 (24) |
| Reduced | 14 (37) | 15 (40) |
| Ceased | 14 (37) | 14 (37) |
| Affected side | ||
| Unilateral, left/right, n (%) | 10 (53) / 9 (47) | 16 (64) / 9 (36) |
| Bilateral, n (%) | 19 (50) | 13 (34) |
| Interventions at the time of study commencement, n (%) | ||
| None | 8 (21) | 5 (13) |
| Patellar strap | 14 (37) | 18 (47) |
| Foot orthoses | 14 (37) | 9 (24) |
| Medical taping | 8 (21) | 6 (16) |
| Knee sleeve | 5 (13) | 2 (5) |
| Ankle brace | 2 (5) | 5 (13) |
| Paracetamol pain killers | 3 (8) | 3 (8) |
| NSAIDs pain killers | 2 (5) | 3 (8) |
| Knee brace | 2 (5) | 1 (3) |
| Cooling | 2 (5) | 1 (3) |
| Warming | 2 (5) | 1 (3) |
| Therapy prior to the time of study commencement, n (%) | ||
| None | 6 (16) | 6 (16) |
| Physical therapy | 28 (74) | 28 (74) |
| Eccentric exercises | 6 (16) | 5 (13) |
| Shock-wave therapy | 6 (16) | 4 (11) |
| Percutaneous needle electrolysis | 2 (5) | 5 (13) |
| Dry needling | 4 (11) | 2 (5) |
| Rest | 2 (5) | 3 (8) |
| Corticosteroid injections | 1 (3) | 2 (5) |
| NSAIDs | 1 (3) | 1 (3) |
| PRP-injections | 0 (0) | 1 (3) |
| Histamine iontophoresis | 1 (3) | 0 (0) |
| Referral | ||
| Sports physician | 11 (29) | 9 (24) |
| Physiotherapist | 16 (42) | 21 (55) |
| General practitioner | 0 (0) | 3 (8) |
| Orthopaedic surgeon | 1 (3) | 2 (5) |
| Self-referral | 10 (26) | 3 (8) |
| US assessment | ||
| Patellar tendon thickness, mm ±SD | 8.2±2.7 | 8.6±2.0 |
| Intratendinous Doppler flow, n (%) | 33 (87) | 36 (95) |
| Hypoechoic regions, n (%) | 38 (100) | 38 (100) |
| Tendon calcifications, n (%) | 9 (24) | 11 (29) |
| Patellar erosions, n (%) | 17 (45) | 7 (18) |
*Data are presented as No. (%) unless otherwise specified.
PRP; platelet-rich plasma; BMI, body mass index; CSAS, Cincinnati Sports Activity Scale; NSAIDs, non-steroidal anti-inflammatory drugs; PT, patellar tendinopathy; US, ultrasound; ; VISA-P, Victorian Institute of Sports Assessment questionnaire for patellar tendons.