Do patients with chronic patellar tendinopathy have an altered somatosensory profile? A Quantitative Sensory Testing (QST) study

The prevalence of tendinopathies in sports is high. The etiology and pain mechanisms of tendinopathies are not completely understood. Currently, little is known whether, or to which degree, somatosensory changes within the nervous system may contribute to the pain in tendinopathies. We conducted a patient controlled study in which we used the standardized QST protocol developed by the German Research Network on Neuropathic Pain. This protocol consists of seven different tests that measures 13 somatosensory parameters and can be seen as the gold standard to measure somatosensory function. Twelve athletes with clinically diagnosed chronic patellar tendinopathy (PT) mean duration 30 months (range 6120) and 20 controls were included in the study. In two of the 13 QST parameters namely Mechanical Pain Threshold (P<0.05) and Vibration Disappearance Threshold (P<0.5) injured athletes were significantly more sensitive for the applied stimuli. None of the athletes had signs of Dynamic Mechanical Allodynia. Reduced mechanical pain thresholds or pinprick allodynia reflects the involvement of central sensitization upon the myelinated (A-fibre) nociceptive input. From this explorative study, we conclude that sensitization may play a prominent role in the pain during and after sports activity in patella tendinopathy patients.