This observational study seeks to identify and validate novel soluble biomarkers (within blood, synovial fluid, urine) which contribute to the prognostic assessment of an individual with an acute knee injury, a group of individuals in which ~50% will progress to symptomatic radiographic knee osteoarthritis (OA).

150 individuals will be followed over 5 years with clinical assessment including validated questionnaires, biological sampling and radiological imaging (X ray, magnetic resonance imaging (MRI)).

Inclusion Criteria:

• Clinically significant acute knee injury within 8 weeks of recruitment
• Aged 16-50
• Knee effusion, evident clinically or by MRI
• Evidence on MRI of structural injury (from list of relevant injuries)
• Informed written consent

Exclusion Criteria:

• Knee injured more than 8 weeks prior to recruitment

• Pre-existing advanced radiographic OA (Kellgren Lawrence (KL) grade 3-4) of same side knee at baseline

• Known history of inflammatory/septic arthritis of same side knee

• Knee replacement - previous or planned within 2 years of study start

• Active other (treated) inflammatory disease or infection

• Positive pregnancy test

• Not consenting, or contraindication to provide blood samples:

  • Bilateral mastectomy
  • Bilateral fistulae for renal dialysis

• Unable to give informed written consent in English

This is a non-intervention cohort study of subjects who have recently sustained a structural knee injury. Individuals are identified from the practice of a collaborating surgeon (AW) at a number of London sites, several of which are within private practice. Because of the practice of the surgeon investigator, a large number will be sporting professionals, or playing amateur sport at a high level.