The OA and Football Study is an epidemiological study designed to establish the prevalence of knee osteoarthritis in retired professional footballers. The study will also identify the key risk factors associated with knee osteoarthritis. The study is comprised of three phases: Phase I involves the dissemination of a questionnaire (demographic details, players history, injury and surgery and other known risk factors of OA), Phase II is a radiographic study that involves x-rays in a sample of footballers both with and without knee pain and Phase III is a case control study which will compared retired professional footballers with age-matched controls recruited from the general population in the East Midlands region.

Number of Participants:

Phase I: 1000 Phase II: 855 Phase III: 500

Primary outcome: The questionnaire will contain player specific information and will include validated outcome measures such as the health status questionnaire as well as self-reported pain, recall of injury and surgery history. The results of the questionnaire will be exported firstly to Excel and subsequently, into MS Access as part of a managed database.

Phase I

Inclusion Criteria:

• All current or retired professional male footballers (Registered with the Professional Footballer Association (age range 40 -80)

Phase II

Inclusion Criteria:

• Professional footballers both with and without a history of knee pain knee OA or knee surgical history
• No contraindications of the affected joint such as gout or rheumatoid arthritis
• Willingness to participate in a clinical assessment of the knee and provision of blood samples.

Phase III

Inclusion Criteria for controls:

• Over the age of 40 (age range 40 - 80)
• Both with and without a history of knee pain over at least the last 1 year
• No history of significant trauma, injury or surgery to the lower limb
• American College of Rheumatology (ACR) classification of OA based on physical examination and clinical presentation: Pain in the knee and three of the following; over the age of 50, less than 30 minutes of morning stiffness, crepitus on active motion, bony tenderness, bony enlargement and no palpable warmth of synovium.

Phase I

Exclusion Criteria:

• Not a registered professional footballer (current or past)
• Inaccurate information (discrepancy with questionnaire information compared to other football records. This will be verified by the co-investigator, Dr Fernandes and Mr Sanjay Parekh)
• Incomplete questionnaire or duplicate questionnaire.

Phase II

Exclusion Criteria:

• Not a registered professional footballer
• No written informed consent to participate

Phase III

Exclusion Criteria:

• Aged 39 and under
• Comorbidities such as rheumatoid arthritis, gout, osteoporosis
• History of injury, trauma or surgery to the lower limb.

Retired footballers will be recruited from a database of retired professional footballers. (cases)

The members of the general public will be recruited from the general population in the East Midlands region. (controls)