Introduction Little is known about the true morbidity of Achilles and patellar tendinopathy in elite athletes. Many studies examine games missed, which underestimates the prevalence of the condition as many athletes continue to play and train with pain.

While there is a disconnect between findings on imaging and clinical symptoms, tendon abnormalities have been suggested to be a risk factor for the development/presence of pain. However, it is unclear whether the amount of disorganisation and/or changes in tendon structure over time affects the presence or magnitude of symptoms in Achilles and patellar tendinopathy.

Methods 430 elite male Australian Football players from 11 clubs were recruited as part of this study. All players completed the OSTRC overuse questionnaire once a month during the AFL season to quantify the impact of Achilles and patellar tendinopathy on participation, ability to train and performance (score out of 100). A subset of 193 participants underwent ultrasound tissue characterisation (UTC) scans of their Achilles and patellar tendons. The presence of pathology on grey-scale was assessed, as well as the percentage of disorganisation structure (DIS) quantified using UTC. Risk factor analysis was performed to identify any associations between tendon structure and symptoms.

Results 13.3% of football players reported some level of Achilles tendon morbidity, whereas patellar tendon morbidity was observed in 16.5% of participants. The average Achilles and patellar tendon severity score was 17.9 (12.2 and 23.7) and 24.3 (18.3 and 30.4). Interestingly, less than 3% of cases were classified as severe.

Imaging was not diagnostic for the presence of patellar tendon pain, as 39.4% of pathological tendons were asymptomatic. Interestingly, players with a pathological tendon on grey-scale US were 7.3 (CI 3.6-14.7) times more likely to have symptoms. Based on UTC findings, participants with more than 5.8% of DIS structure were 5.1 times more likely to have their tendon affect their ability to train and perform.

Discussion Traditional injury surveillance appears to underreport the prevalence of Achilles and patellar tendinopathy in the Australian Football League. While severe cases of tendinopathy were limited, there are a number of athletes that have Achilles and patellar tendinopathy limiting their ability to fully participate and perform. While abnormal tendon structure was a risk factor for the presence of pain, imaging should not be used diagnostically due to high number of asymptomatic tendon pathology and poor precision. These findings are critical for future injury prevention studies.