Obesity and osteoarthritis (OA) co-exist in an increasing part of the population.The two diseases intertwine in several ways. The evolution in the population shows a tendency towards deterioration of both by increasing general age and weight. The two diseases share pathogenetic features and the development of one disease increases the risk of the other and may be the onset of a vicious circle.There is a link between treatments of these two diseases as well. There is now solid (gold) evidence that by treating effectively the obesity of patients with co-occurring OA, the functional status is dramatically ameliorated; the short-term results are equal to that of a joint replacement. The long-term efficacy of a weight loss remains to be shown. OA is definitely one of many diseases in which obesity must be taken seriously into account when planning a correct treatment of patients. This trial has two phases, the first (16 weeks) consisting of a dietary intervention with low-energy diet and the second (52 weeks) a randomised, three group (each n>50 patients) controlled study of maintenance of weight loss by either continuing dietary instruction, exercise, or a control group. The hypothesis is that maintenance of an initially induced weight loss is dependent on attention rather than any specific therapy.

Official Title

Influence of Weight Loss or Exercise on Cartilage in Obese Knee Osteoarthritis Patients: A Randomised Controlled Trial (CAROT).


  • Osteoarthritis, Knee
  • Obesity

Study Type


Study Design

Treatment, Randomised, Single Blind (Outcomes Assessor), Active Control, Parallel Assignment, Efficacy Study

Further Details

Primary Outcome Measures:

  • Pain 
  • OMERACT-OARSI response criterion

Secondary Outcome Measures:

  • Weight change
  • Gait analysis
  • MRI
  • Ultrasound
  • Collagen markers
  • Metabolic syndrome
  • KOOS

Study Start

April 2008

Eligibility & Criteria


  • Ages Eligible for Study: 50 years and older
  • Genders Eligible for Study: Both
  • Accepts Healthy Volunteers: No


Inclusion Criteria:

  • BMI ≥ 30
  • Radiographical knee OA
  • Age ≥ 50
  • Spoken Danish
  • Motivated for weight loss

Exclusion Criteria:

  • Bilateral alloplasty of the knees
  • Ongoing or planned surgery
  • Ongoing or planned alternative weight loss program
  • Intellectual disability

Total Enrolment


Contact Details

Please refer to this study by its ClinicalTrials.gov identifier: NCT00655941


Henning Bliddal, Professor, MD  
45-3816-4158 ext 4158

Birgit Falk Riecke, MD
45-3816-4158 ext 4158


The Parker Institute, Frederiksberg Hospital Recruiting
Frederiksberg, Denmark, 2000


Line Rustad, Secretary
45-3816-4158 ext 4158

Claus Bomhoff, MA
45-3816-4158 ext 4158

Sponsors and Collaborators

Frederiksberg University Hospital
The Velux Foundation
The Oak Foundation
Danish Rheumatism Association
Cambridge Health & Weight Plan, UK


Study Director:      

Henning Bliddal, Professor, MD 
The Parker Institute, Frederiksberg Hospital