Patellar Tendinopathy and Potential Risk Factors: An International Database of Cases and Controls.
OBJECTIVE
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.


METHODS
Case-control study.


METHODS
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.


METHODS
Eight hundred twenty-five data sets collected between January 2012 and May 2014.


METHODS
A total of 23.4% of participants had clinically diagnosed PT. A comparison between these participants and participants without PT was made.


METHODS
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.
*Sports and Exercise Medicine, William Harvey Research Institute, Queen Mary University of London, Mile End Hospital, London, United Kingdom; †Department for Health, University of Bath, Bath, United Kingdom; ‡FC Barcelona, Ciutat Esportiva JOAN GAMPER, Sant Joan, Despí Barcelona, Spain; §A.S. Volley Lube, Macerata, Italy; ¶Royal Spanish Volleyball Federation, Madrid, Spain; ‖Department of Physiotherapy, School of Primary Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Frankston, Victoria, Australia; #BMI London Independent Hospital, London, United Kingdom; and **Department of Phyisotherapy, Barts Health NHS Trust, London, United Kingdom.
Sarah
S
Morton
Sean
S
Williams
Xavier
X
Valle
David
D
Diaz-Cueli
Peter
P
Malliaras
Dylan
D
Morrissey
D000328:Adult; D056352:Athletes; D001416:Back Pain / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007558:Italy; D007718:Knee Injuries / Q000453:epidemiology; D008297:Male; D010329:Patella / Q000503:physiopathology*; D012307:Risk Factors; D013030:Spain; D011795:Surveys and Questionnaires; D052256:Tendinopathy / Q000453:epidemiology*; D013708:Tendon Injuries / Q000453:epidemiology; D006113:United Kingdom; D055815:Young Adult