Changes in water content in response to an acute bout of eccentric loading in a patellar tendon with a history of tendinopathy: A case report

Objective: This case-based report assessed resting water content and exercise-driven water exchange within a tendon with a history of tendinopathy and compared the response to that of a healthy uninvolved tendon. Design: Case Report. Setting: University imaging center. Participant: The participant was a 27-year-old female basketball player 39 months following knee trauma. Patellar tendinopathy developed 12 months after the injury episode and was treated with eccentric exercises. Eighteen months from the beginning of the first eccentric training bout, the participant reported full resolution of symptoms and returned to her pre-injury sport participation without symptoms. Intervention: Eccentric decline squat exercise. Main Outcome Measures: Tendon water content obtained from magnetic resonance imaging (MRI). Results: MRI acquired 39 months post-injury demonstrated increased resting water content of the involved tendon (involved: 91.1% vs. uninvolved: 84.6%). Immediately after the eccentric squat maneuver, water content decreased on both involved and uninvolved tendons (involved: 89.5% vs. uninvolved: 83.3%). Conclusions: Elevated resting water content of the involved tendon found in this report may be indicative of reduced tendon stiffness. A similar amount of water content reduction was observed on both sides following mechanical loading, suggesting that the involved tendon may respond to the eccentric exercise similarly to the uninvolved tendon. Future investigations are needed to study the relationships among tendon water exchanges, mechanical properties, patient symptoms, and tissue injuries.