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Dear Dr Breda and colleagues,
Thanks for your insightful publication. I would like to add to Georg Supp and Stephanie Moers comments on this article.
I agree with the previous comments that the current experimental design is more a comparison between the effectiveness of low pain loading exercise and painful loading exercise in patients with patellar tendinopathy according to the current methodology.
As a fairer comparison, it should be rather progressive tendon-loading exercise versus statics/ regressive loading exercise. Otherwise, it can also be progressive isometric & isotonic tendon-loading exercise versus progressive eccentric loading exercise as well. No clear standardization on the loading of the exercise makes it less convincing to achieve the authors’ conclusion.
We would like to congratulate the authors on this interesting publication. The supplementary material is of especially high value and we appreciate how it can assist clinicians to evaluate the described program in their daily clinical practice. The studied progressive tendon-loading program reflects, in many aspects, what we find effective with our athletic and non-athletic patient population in our clinic.
However, from our perspective there are some issues with the study that question the authors’ conclusion of a superiority of Progressive Tendon-Loading Exercise Therapy (PTLE) over Eccentric Exercise Therapy (EET).
1. Does the study truly compare PTLE with EET?
In stage 1, patients in the EET group were instructed to perform the exercises with pain VAS ≥ 5/10, whereas the PTLE group performed the exercises ‘within the limits of acceptable pain’. This requirement adds a non-controlled variable. Does the study solely compare the effect of two different progressing loading regimes, or does it compare painful exercises with exercises performed in an acceptable range of pain?
What matters most here? The program or the pain?
2. How do the authors justify the ≥ 5 VAS in the EET group?
Instructing patients to perform exercises that produce at least a pain of VAS 5 is uncommon. To justify this, Breda et al. refer to the study of Visnes (2005).1 This RCT with 29 volleyball players with patellar tendinopathy had shown no effect on knee funct...
2. How do the authors justify the ≥ 5 VAS in the EET group?
Instructing patients to perform exercises that produce at least a pain of VAS 5 is uncommon. To justify this, Breda et al. refer to the study of Visnes (2005).1 This RCT with 29 volleyball players with patellar tendinopathy had shown no effect on knee function from a 12-week program with painful eccentric training. To our knowledge, this is the only study where VAS ≥ 5 was used as a requirement. In most studies on tendinopathy and eccentric training, a pain VAS ≤ 5 is recommended.2-4
What is the rationale behind choosing a specific program which had already been found to be ineffective, whereas other eccentric regimes had shown at least some efficacy?5,6
3. Inconsistency in patient education
In the supplemental material the authors refer to the colored pain scale for use in the education of the EET group. This scale clearly identifies a pain above 5 as being in the ‘high-risk-zone’. How does this fit with the instruction for patients to exercise with VAS ≥ 5? Patients might well be fearful of reinjuring their tendon when performing this degree of painful exercise.
4. Insufficient adherence to the programs
How low is too low?
Earlier studies on tendinopathy describe adherence rates between 50 and 79 %.4,7-10
Patients in the PTLE group and EET group only reached an adherence of 40% and 49 % respectively after 24 weeks. The adherence to exercises targeting risk factors was only 21% and 22 % respectively. Even if no significant between-group differences were found for exercise adherence, the low adherence in both groups should be mentioned in the limitation section of the study.
With 76 patients included, this RCT is the largest clinical trial in patients with patellar tendinopathy to date. It raised exceptional attention.11 Nevertheless, the concerns mentioned above might justify some caution concerning the clinical impact of the study.
1. Visnes H, Hoksrud A, Cook J, Bahr R. No effect of eccentric training on jumper's knee in volleyball players during the competitive season: a randomized clinical trial. Clin J Sport Med. 2005;15(4):227-234. doi:10.1097/01.jsm.0000168073.82121.20
2. Kongsgaard M, Kovanen V, Aagaard P, et al. Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy. Scand J Med Sci Sports. 2009;19(6):790-802. doi:10.1111/j.1600-0838.2009.00949.x
3. Silbernagel KG, Thomeé R, Thomeé P, Karlsson J. Eccentric overload training for patients with chronic Achilles tendon pain--a randomised controlled study with reliability testing of the evaluation methods. Scand J Med Sci Sports. 2001;11(4):197-206. doi:10.1034/j.1600-0838.2001.110402.x
4. Roos EM, Engström M, Lagerquist A, Söderberg B. Clinical improvement after 6 weeks of eccentric exercise in patients with mid-portion Achilles tendinopathy -- a randomized trial with 1-year follow-up. Scand J Med Sci Sports. 2004;14(5):286-295. doi:10.1111/j.1600-0838.2004.378.x.
5. Everhart JS, Cole D, Sojka JH, et al. Treatment Options for Patellar Tendinopathy: A Systematic Review. Arthroscopy. 2017;33(4):861-872. doi:10.1016/j.arthro.2016.11.007
6. Woodley BL, Newsham-West RJ, Baxter GD. Chronic tendinopathy: effectiveness of eccentric exercise. Br J Sports Med. 2007;41(4):188-98; discussion 199. doi:10.1136/bjsm.2006.029769
7. Knobloch K, Schreibmueller L, Longo UG, Vogt PM. Eccentric exercises for the management of tendinopathy of the main body of the Achilles tendon with or without an AirHeel Brace. A randomized controlled trial. B: Effects of compliance. Disabil Rehabil. 2008;30(20-22):1692-1696. doi:10.1080/09638280701785676
8. Sayana MK, Maffulli N. Eccentric calf muscle training in non-athletic patients with Achilles tendinopathy. J Sci Med Sport. 2007;10(1):52-58. doi:10.1016/j.jsams.2006.05.008
9. Vos RJ de, Weir A, Visser RJA, Winter T de, Tol JL. The additional value of a night splint to eccentric exercises in chronic midportion Achilles tendinopathy: a randomised controlled trial. Br J Sports Med. 2007;41(7):e5. doi:10.1136/bjsm.2006.032532
10. Young MA, Cook JL, Purdam CR, Kiss ZS, Alfredson H. Eccentric decline squat protocol offers superior results at 12 months compared with traditional eccentric protocol for patellar tendinopathy in volleyball players. Br J Sports Med. 2005;39(2):102-105. doi:10.1136/bjsm.2003.010587
11. Altmetric. Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomised clinical trial: Overview of attention for article published in British Journal of Sports Medicine, November 2020. https://bmj.altmetric.com/details/94665680