Oxford Knee Score Calculator
Assess knee function and pain using the 12-question Oxford Knee Score questionnaire. Enter values for instant results with step-by-step formulas.
Formula
OKS = Sum of 12 items (each scored 0-4)
Each of the 12 questions is scored from 0 (worst/most severe) to 4 (best/no symptoms). Total score ranges from 0 (worst possible) to 48 (best possible knee function). Higher scores indicate better outcomes.
Worked Examples
Example 1: Pre-Operative Knee Replacement Assessment
Problem: A 68-year-old patient with severe knee osteoarthritis is being assessed before total knee replacement. They report severe pain most of the time, cannot walk more than a few hundred yards, have significant difficulty with stairs, and cannot kneel at all.
Solution: Pain level: 1 (Moderate-Severe)\nWashing: 2 (Mild difficulty)\nTransport: 1 (Moderate difficulty)\nWalking distance: 1 (Short distance)\nStanding from chair: 1 (Very painful)\nLimping: 1 (Sometimes)\nKneeling: 0 (Cannot kneel)\nNight pain: 1 (Most nights)\nWork interference: 1 (Moderately)\nGiving way: 1 (Sometimes)\nShopping: 2 (With difficulty)\nStairs: 1 (One step at a time)\nTotal = 13/48
Result: Oxford Knee Score: 13/48 (Severe arthritis) - Surgery indicated based on functional limitation
Example 2: One Year Post-Operative Follow-Up
Problem: The same patient returns one year after total knee replacement. They report occasional mild pain, can walk for over 30 minutes, manage stairs normally, and have returned to most daily activities without significant limitation.
Solution: Pain level: 3 (Mild)\nWashing: 4 (No trouble)\nTransport: 4 (No trouble)\nWalking distance: 3 (30+ minutes)\nStanding from chair: 3 (Slightly painful)\nLimping: 3 (Rarely)\nKneeling: 2 (With difficulty)\nNight pain: 4 (No nights)\nWork interference: 3 (A little)\nGiving way: 4 (Never)\nShopping: 4 (Easily)\nStairs: 3 (Mild difficulty)\nTotal = 40/48
Result: Oxford Knee Score: 40/48 (Satisfactory function) - 27-point improvement, excellent surgical outcome
Frequently Asked Questions
What is the Oxford Knee Score and what does it measure?
The Oxford Knee Score (OKS) is a 12-item patient-reported outcome measure specifically designed and developed to assess function and pain after total knee replacement surgery. It was created at the University of Oxford by researchers Dawson, Fitzpatrick, Carr, and Murray and first published in 1998 as a validated assessment tool. Each question is scored from 0 to 4, giving a total score range of 0 (worst possible) to 48 (best possible outcome). The OKS captures the patient perspective on knee function covering activities of daily living, pain levels, and mobility limitations that are most relevant to knee replacement patients.
How is the Oxford Knee Score calculated and interpreted?
The Oxford Knee Score is calculated by summing the responses to all 12 questions, where each item is scored from 0 (most severe symptoms) to 4 (least symptoms). The total score ranges from 0 to 48, with higher scores indicating better knee function and less pain. Scores of 0 to 19 indicate severe knee arthritis or poor surgical outcome, scores of 20 to 29 indicate moderate to severe problems, scores of 30 to 39 suggest mild to moderate difficulties, and scores of 40 to 48 represent satisfactory joint function. The minimal clinically important difference for the OKS is generally considered to be around 4 to 5 points.
When should the Oxford Knee Score be used in clinical practice?
The Oxford Knee Score should be administered before knee replacement surgery to establish a baseline measurement and then at regular follow-up intervals post-operatively, typically at 6 months, 1 year, and annually thereafter. It is specifically designed for assessing total knee arthroplasty outcomes rather than general knee conditions or sports injuries. Many national joint registries around the world, including the UK National Joint Registry, require the OKS as a mandatory outcome measure for knee replacement procedures. The questionnaire takes approximately 5 minutes to complete and can be self-administered by patients without clinician assistance.
What is a good Oxford Knee Score after knee replacement surgery?
A good Oxford Knee Score after total knee replacement is generally considered to be 35 or above, indicating mild or no residual knee problems from the surgical intervention. Most successful knee replacements achieve OKS scores between 35 and 45 at one year post-operatively, representing significant improvement from pre-operative baseline scores. The average improvement expected after a primary total knee replacement is approximately 15 to 20 points from the pre-operative score. Scores above 40 are considered excellent outcomes, while scores below 25 at one year may warrant further clinical investigation into potential complications or mechanical issues.
How does the Oxford Knee Score compare to other knee assessment tools?
The Oxford Knee Score is considered one of the most validated and responsive patient-reported outcome measures for knee replacement assessment specifically. Unlike the WOMAC (Western Ontario and McMaster Universities Arthritis Index) which covers general osteoarthritis, the OKS focuses specifically on issues relevant to knee replacement patients. Compared to the Knee Society Score which requires clinical examination, the OKS is entirely patient-reported and does not require a healthcare professional to administer. The American Knee Society Score and the KOOS (Knee injury and Osteoarthritis Outcome Score) are broader instruments that may be more appropriate for non-arthroplasty knee conditions.
Can the Oxford Knee Score detect complications after knee replacement?
While the Oxford Knee Score is primarily designed to measure functional outcomes rather than diagnose specific complications, persistently low or declining scores can serve as a red flag indicating potential problems after knee replacement surgery. A score that fails to improve beyond 20 points at six months post-operatively may suggest issues such as infection, implant loosening, instability, or stiffness requiring further investigation. However, the OKS should not be used as a standalone diagnostic tool for complications because low scores can also reflect patient expectations, psychological factors, or comorbid conditions. Clinical examination and imaging remain essential for diagnosing specific post-operative complications.