WOMAC Osteoarthritis Index: Scoring, Subscales and Clinical Interpretation
In short
The WOMAC Osteoarthritis Index is the premier clinical trial and rehabilitation measure for hip and knee osteoarthritis. Learn its scoring structure, interpretation and MCID.
In this guide (5 sections)
What Is the WOMAC Index?
The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was created by Nicholas Bellamy in 1982 to evaluate symptom severity and functional limitations in hip and knee osteoarthritis.
Consisting of 24 questions divided into 3 subscales, the instrument is available in either a 5-point Likert scale format (0 = None to 4 = Extreme) or a 100 mm visual analog scale (VAS) format.
The 3 Subscales and Scoring Breakdown
The 5-point Likert scale is the most commonly used clinical version. Higher WOMAC scores indicate greater pain, stiffness and physical functional disability.
The total raw score can range from 0 to 96 points across the three domains.
| Subscale | Number of Items | Score Range (Likert 0-4) | Core Activities Assessed | |
|---|---|---|---|---|
| Pain | 5 items (A1-A5) | 0 to 20 points | Walking on flat ground, going up/down stairs, resting in bed, sitting, standing upright. | |
| Stiffness | 2 items (B1-B2) | 0 to 8 points | Morning waking stiffness, stiffness after sitting, lying or resting later in the day. | |
| Physical Function | 17 items (C1-C17) | 0 to 68 points | Stairs, rising from sitting, standing, bending, walking, getting in/out of car, shopping, dressing, bath/shower. | |
| Total WOMAC Score | 24 items | 0 to 96 points | Global evaluation of lower extremity osteoarthritic impairment. |
Minimal Clinically Important Difference (MCID)
In osteoarthritis clinical trials and outpatient rehabilitation, an absolute improvement of 9 to 12 points on the total WOMAC score (or a 12 to 15 percent relative reduction from baseline) represents a clinically meaningful difference.
According to OMERACT-OARSI responder criteria, high clinical improvement requires at least a 50 percent relative reduction in pain or function, or at least a 20 percent reduction accompanied by an absolute score change of 10 or more points.
- Pre-arthroplasty: Patients scheduled for total knee replacement typically present with total WOMAC scores between 50 and 75.
- Post-arthroplasty: At 6 months post-surgery, average WOMAC scores drop down to 10 to 20 points.
- Conservative exercise therapy: Supervised strengthening yields an average 12 to 18 point reduction over an 8-week cycle.
Indian Lifestyle Adaptations for WOMAC
Several WOMAC Physical Function items (such as putting on socks, getting in/out of a bath, and heavy domestic duties) require contextualization in Indian households.
In India, bathing often involves bucket-and-mug use on low stools rather than stepping into an acrylic bathtub. Dressing frequently involves tying dhotis, saris or salwar strings while balancing on one leg. Documenting these specific functional challenges improves therapy goal-setting.
Frequently Asked Questions
What is the main difference between WOMAC and KOOS?
WOMAC was designed specifically for older adults with degenerative osteoarthritis and joint replacement candidates. KOOS includes higher-demand athletic and recreational tasks (jumping, pivoting, twisting) suitable for sports injuries.
Can WOMAC scores be reported as a percentage?
Yes. Many clinics normalize the raw score out of 96 to a 0 to 100 percentage scale: (Raw Score / 96) * 100, where 0% represents no disability and 100% represents maximum impairment.
How long does WOMAC take to complete?
The self-administered 5-point Likert version typically takes 5 to 7 minutes for a patient to complete.
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