Isokinetic profile of subjects with proximal patellar tendinopathy

Introduction
Patellar tendinopathy (PT) is commonly observed in jumping sports. Even if its biomechanic is somewhat explored, no information is known about the muscle strength profile of these patients. We aimed to determine if there exists a specific profile of patients suffering from a PT

Methods
43 patients (42 males; 29 y.o +/- 9.8 y.o) suffering from PT were recruited. To be eligible, the patients must not have suffered from any other traumatic or micro-traumatic injury than the PT on the pathologic limb. After a physical examination, the tendon damage was assessed by ultrasounds examination. The patients were then tested on an isokinetic dynamometer and the peak torque per unit of mass (PTm) developed by the quadriceps and the hamstrings were recorded for various testing modalities. After each test, a visual analog scale (VAS) was used to estimate the pain felt by the patients.

Results
No significant correlation was found between the MTm and the demographic variables. The difference in MTm between the healthy and the pathological limbs was significant only in concentric 60°/s, for both the quadriceps and the hamstrings. Lastly, the VAS score showed that the most intense pain was experienced after the eccentric test.

Conclusions
There is no specific patient strength profile emerging from the isokinetic test. This stresses the importance for the clinicians to make testing and to apply a personalized treatment to each patient. On the other hand, the isokinetic eccentric testing of the quadriceps could be used to induce a mechanical stress on the tendon for a reliable pain assessment.