Pain assessment in patellar tendinopathy using pain pressure threshold algometry: an observational study.

OBJECTIVE: Assessing pain in patellar tendinopathy (PT) is difficult to perform in a standardized way. With this study, we measured pain in athletes with PT by means of pain pressure threshold (PPT) algometry in a standardized manner. Subsequently, the goal of this study is to determine normative values for clinical use. DESIGN: Observational study. SETTING: Patients and healthy subjects were recruited from an outpatient clinic of a university medical center and at different sports clubs in northern Netherlands. SUBJECTS: A total of 234 athletes, 114 diagnosed with PT and 120 healthy controls, were included. OUTCOME MEASURES: PPT, Victorian Institute of Sport Assessment-Patellar tendinopathy questionnaire, and visual analog scale-pain. RESULTS: PPT scores of PT athletes with tendinopathy were significantly lower compared with healthy athletes (Mann-Whitney U-test; U = 293.5; P < 0.001). With a receiver operating characteristic (ROC) curve, the optimal cut-off point to distinguish between healthy athletes and PT athletes was calculated at 36.8 N. The area under the ROC curve was 0.98 (95% CI: 0.96-1.0). There was a positive predictive value of 96.5% that athletes with a PPT below 36.8 N. had PT. CONCLUSIONS: PPT algometry should be considered by clinicians as a pain assessment tool in patients with PT. The optimal cut-off point for the PPT to distinguish between PT athletes and healthy athletes was 36.8 N.