Exercise Therapy for Patellar Tendinopathy Evaluated With Advanced UTE-MRI

Patellar tendinopathy is a frequent overuse injury that causes pain and impaired performance in jumping athletes. Exercise therapy is considered the best initial treatment option for tendinopathies as clinical improvements in pain and function have been demonstrated. Although painful eccentric exercise protocols have been promoted as standard care based on positive results in early studies, a recent systematic review demonstrated that these are not associated with improved tendon structure and are ineffective when applied in-season. Progressive tendon-loading exercise therapy for patellar tendinopathy constitutes a novel concept in sports medicine. A recent study advocates a progressive 4-stage criteria-based exercise protocol as it results in a less reactive tendon and ability to restore collagen alignment. This protocol consists of progressive isometric, isotonic, plyometric, and sport-specific exercises. Isometric exercises have been shown to reduce pain and decrease motor cortex inhibition of the quadriceps. This approach would enable jumping athletes to resume sports within the limits of pain, with improved muscle function, and sufficient tendon structure re-organization. The diagnostic imaging work-up of patellar tendinopathy typically consists of ultrasound, magnetic resonance imaging (MRI), or a combination of both. Ultrashort echo time (UTE) MRI is an advanced MRI technique, which enables assessment of tissues with short T2-time, such as tendon, the structure of which is invisible on regular MRI. UTE has been shown to quantitatively depict changes in tendon microstructure and therefore allows in-vivo evaluation of tendon regeneration. It is currently unknown whether quantitative UTE MRI parameters change after exercise treatment, are related to clinical symptoms of patellar tendinopathy, have prognostic value for exercise treatment response, and offer additional value over ultrasound