About the WOMAC Osteoarthritis Index
The Western Ontario and McMaster Universities Arthritis Index (WOMAC) is the gold-standard questionnaire for assessing osteoarthritis of the hip and knee. Originally developed in 1982, it evaluates pain, stiffness, and physical function in patients with osteoarthritis. The WOMAC is widely used in clinical practice and research to monitor disease progression, evaluate treatment effectiveness, and assess outcomes following joint replacement surgery.
Medical Specialties
Anatomic Areas
Clinical Indications
Developer Information
The WOMAC was developed by researchers at the Western Ontario and McMaster Universities in London, Ontario, Canada, in 1982. It was created by Dr. Nicholas Bellamy and colleagues as a multidimensional, disease-specific, self-administered health status instrument for use in patients with osteoarthritis of the hip and/or knee. The questionnaire has undergone extensive validation and is recognized internationally as a standard outcome measure in osteoarthritis research.
Copyright & Licensing
The WOMAC is a copyrighted instrument and ownership is held by the developers. Permission for use must be obtained from the copyright holders or through the appropriate licensing authorities. The questionnaire is widely used in clinical trials and research, and licensing information can be obtained through official channels. Users should verify current licensing requirements before implementation in clinical practice or research studies.
Administration Instructions
Answer all questions about your knee/hip condition over the last 48 hours. For each question, select the response that best describes your experience using the 5-point scale (0 = None to 4 = Extreme).
Scoring Methodology
The WOMAC uses a 5-point Likert scale (0-4) for each question: 0 = None, 1 = Slight, 2 = Moderate, 3 = Severe, 4 = Extreme. Higher scores indicate worse symptoms. The questionnaire consists of 24 items divided into 3 subscales: Pain (5 items, score range 0-20), Stiffness (2 items, score range 0-8), and Physical Function (17 items, score range 0-68). Domain scores are summed to create a total score (0-96), which can be normalized to a 0-100 scale for standardized reporting.
Meaningful Change Threshold
A change of approximately 10% in any domain is generally considered a meaningful improvement or worsening. For the total score, a change of 8-12 points represents clinically meaningful change. Minimal clinically important difference (MCID) values vary by context: post-surgical improvement typically requires 10-20 point change, while disease progression monitoring may use 5-10 point thresholds.
Score Interpretation
Understanding what your score means
mild
0 - 25Mild osteoarthritis symptoms with minimal impact on daily activities and quality of life
moderate
26 - 50Moderate osteoarthritis symptoms with some functional limitations and discomfort during activities
severe
51 - 75Severe osteoarthritis symptoms with significant functional impairment and considerable pain
very severe
76 - 100Very severe osteoarthritis symptoms with major impact on independence and daily functioning
Subscales
This questionnaire measures multiple dimensions
Pain (0-20)
Pain during walking, using stairs, in bed at night, sitting or lying, and standing
Physical Function (0-68)
Difficulty with daily activities including descending stairs, ascending stairs, rising from sitting, standing, bending to floor, walking on flat surface, getting in/out of car, going shopping, putting on socks, rising from bed, taking off socks, lying in bed, getting in/out of bath, sitting, getting on/off toilet, heavy domestic duties, and light domestic duties
Stiffness (0-8)
Stiffness after first waking in the morning and later in the day after sitting, lying, or resting
Clinical Limitations & Considerations
The WOMAC is specific to osteoarthritis of the hip and knee and may not be suitable for assessing other joint conditions or types of arthritis. As a self-reported measure, it may be influenced by patient mood, expectations, recall bias, or cultural factors. The time frame of "last 48 hours" may limit sensitivity to longer-term changes or day-to-day variability in symptoms. The questionnaire does not assess all aspects of quality of life and should be considered as part of a comprehensive clinical assessment rather than as a standalone diagnostic tool. Floor and ceiling effects may occur in patients with very mild or very severe disease.
Supporting Literature
Key validation and development studies for the WOMAC Osteoarthritis Index
- 1
Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee
Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW
The Journal of Rheumatology, 1988
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This questionnaire is provided free of charge. Patient Watch charges only for platform services (data storage, automated reminders, analytics) - not for use of clinical instruments. This non-commercial model supports academic and clinical use. View full licensing disclosure