Patellar Tendinopathy and Potential Risk Factors: An International Database of Cases and Controls
Numerous risk factors have been identified for patellar tendinopathy (PT), often in small population studies. The aim was to use an international online questionnaire to generate a large database and identify significant risk factors.Design:
Private practice and sporting teams recruited from England, Spain, and Italy with the questionnaire available in all 3 languages (equivalence between online and self-administration shown previously). All data were anonymized and password protected.Participants:
Eight hundred twenty-five data sets collected between January 2012 and May 2014.Assessment of Risk Factors:
A total of 23.4% of participants had clinically diagnosed PT. A comparison between these participants and participants without PT was made.Main Outcome Measure:
Association between the presence of PT and risk factors.Results:
Eight risk factors were included in the analysis based on a purposeful selection procedure: sex, hours of training, hamstring flexibility, previous patellar tendon rupture, previous knee injury, current/previous back pain, family history, and age. Four were found to have statistically significant odds ratios: female sex [0.70, 95% confidence interval (CI), 0.49-1.00, P = 0.05], hours of training (>20 hours 8.94, 95% CI, 4.68-17.08, P < 0.01), previous knee injury (2.10, 95% CI, 1.45-3.04, P < 0.01), and flexible hamstrings (0.61, 95% CI, 0.38-0.97, P = 0.04). There was a trend toward association for back pain (1.45, 95% CI, 0.99-2.14, P = 0.06) and a family history of tendon problems (1.51, 95% CI, 0.96-2.37, P = 0.08).Conclusions:
Risk factors have been identified that are potentially modifiable to inform prevention and rehabilitation programs; future research is required to establish causal relationships. Identified risk factors require mechanistic investigation as they are not currently recognized in the literature.