Transcranial Direct Current Stimulation on Functionality and Pain in Individuals with Patellar Tendinopathy

The aim of the present study is to investigate the effectiveness of transcranial direct current stimulation (tDCS) prior to a therapeutic eccentric exercise program on parameters related to pain and functionality in individuals with patellar tendinopathy. For this purpose, participants will be randomly divided into two groups: i) experimental group, receiving tDCS prior to a therapeutic exercise program; and ii) control group, receiving sham tDCS and a therapeutic exercise program. The interventions will last for 8 weeks. Additionally, four assessments will be conducted (baseline, week 4, week 8 and week 12). The variables studied are related to pain, functionality, muscle activity and strength, proprioception, and quality of life.

Patellar tendinopathy is a painful condition affecting the anterior portion of the knee, commonly exacerbated by activities putting pressure on the patellofemoral joint. It remains a challenge for the healthcare system, not only due to its high prevalence, but also because of its high persistence and negative consequences. Although therapeutic exercise has been widely studied as a treatment strategy, eccentric exercise protocols, while effective, often require long application periods, which may affect treatment adherence. Additionally, eccentric exercise is pain-provoking and its therapeutic benefits for pain relief and functional improvement are controversial when used during the competitive season. More adaptable and personalized treatment strategies could enhance clinical outcomes and treatment adherence in patients with patellar tendinopathy. In this context, interventions combining exercise with other techniques have been proposed. However, existing evidence does not definitively determine the optimal approach for combining conservative treatment options to maximize benefits.

An emerging therapeutic approach combines Transcranial Direct Current Stimulation (tDCS) with therapeutic exercise protocols. tDCS involves the application of weak direct current to specific cortical areas, aiming to modulate brain excitability. This non-invasive method offers painless, selective, and focal stimulation with minimal side effects. Research increasingly supports the effectiveness of integrating tDCS with exercise for patellar tendinopathy, offering the potential to amplify exercise effects by modulating brain excitability. However, to date, no study has investigated the impact of tDCS combined with eccentric exercise on variables related to function and pain in patellar tendinopathy individuals.

Therefore, the aim of this study is to investigate the effectiveness of tDCS prior to a therapeutic eccentric exercise program on parameters related to pain and functionality in individuals with patellar tendinopathy.

This study is a randomized clinical trial in which two groups will participate, with different interventions: i) Experimental group: tDCS + Therapeutic eccentric exercise; and ii) Control group: Sham tDCS + Therapeutic eccentric exercise. The interventions will last for 8 weeks. Participants will be evaluated in four moments, at baseline, week 4, week 8 and week 12. The variables studied are related to pain, functionality, muscle strength and activity, proprioception, and quality of life.

Eligibility Criteria:
Inclusion Criteria:

* Age between 18 and 50 years.
* Diagnosis of patellar tendinopathy (VISA-P score of 80 or lower).
* Pain lasting more than 3 months.

Exclusion Criteria:

* Previous knee surgery.
* Corticosteroid injection in the previous 6 weeks.
* Systemic inflammatory, autoimmune, or rheumatic diseases.
* Cognitive or behavioural issues that hinder comprehension and adherence to the intervention.
* Any neurological disease.
* Neoplastic disease.
* Subjects presenting contraindications for tDCS (Thair et al., 2017), including: personal and family history of epilepsy, metallic implants in the head, implanted medication pump, pacemaker, recurrent headaches, skin conditions (psoriasis, eczema), or major head surgeries, pregnancy, heart diseases, and various medications (psychotropic or antihistamines).
* Subjects must not have undergone pharmacological treatment or knee physical rehabilitation programs for a period of 1 year.