Oxford Knee Score

Original Editor - Lauren Lopez Top Contributors - Lauren Lopez


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Top Contributors - Lauren Lopez  

Objective

The Oxford Knee Score (OKS) was developed in 1998 and validated to measure pain and function after total knee replacement[1].

Intended Population

The OKS was originally developed and validated for use with individuals undergoing knee arthroplasty but has also been used to measure outcomes in pharmacological treatments, after osteotomies, following rehabilitation or with fractures[2]. It is a primary outcome measure of choice for national audits of knee replacements[3]. It has also been used to predict revisions six months after replacement[4].

Method of Use

The OKS is a patient reported outcome measure that consists of 12 questions obout an individual's activities of daily living and how they have been affected by pain over the preceding four weeks.

Questions

The patient is first asked to date their questionnaire and confirm which side/leg they are receiving treatment for. If both knees are involved, a questionnaire is done for each leg[5].

From Dawson et al 1998[1] and Oxford University Innovation[5]
Questions Scoring
  1. How would you describe the pain you usually have from your knee?
None

Very mild

Mild

Moderate

Severe

2. Have you had any trouble with washing and drying yourself (all over) because of your knee? No trouble

Very little trouble

Moderate trouble

Extreme difficulty

Impossible to do

3. Have you had any trouble getting in and out of a car or using public transport because of your knee? (whichever you tend to use) No trouble

Very little trouble

Moderate trouble

Extreme difficulty

Impossible to do

4. For how long have you been able to walk before the pain from your knee becomes severe (with or without a stick) No pain/more than 30 minutes

16 to 30 minutes

5 to 15 minutes

Around the house only

Not at all/pain severe when walking

5. After a meal (sat at a table), how painful has it been for you to stand up from a chair because of your knee? Not at all painful

Slightly painful

Moderately painful

Very painful

Unbearable

6. Have you been limping when walking, because of your knee? Rarely/ never

Sometimes, or just at first

Often,not just at first

Most of the time

All of the time

7. Could you kneel down and get up again afterwards? Yes, easily

With little difficulty

With moderate difficulty

With extreme difficulty

No, impossible

8. Have you been troubled by pain from your knee in bed at night? No nights

Only 1 or 2 nights

Some nights

Most nights

Every night

9. How much has pain from your knee interfered with your usual work (including housework)? Not at all

A little bit

Moderately

Greatly

Totally

10. Have you felt that your knee might suddenly “give way” or let you down? Rarely/ never

Sometimes, or just at first

Often, not just at first

Most of the time

All of the time

11. Could you do the household shopping on your own? Yes, easily

With little difficulty

With moderate difficulty

With extreme difficulty

No, impossible

12. Could you walk down a flight of stairs? Yes, easily

With little difficulty

With moderate difficulty

With extreme difficulty

No, impossible

Scoring

When the OKS was originally developed, it was designed to be as simple as possible in order to promote use. The original scoring system was a 1-5 where one represented the best outcome[5]. However, clinicians found this confusing in practice and adaptations began to appear so the original authors developed a new scoring system from 0-4 where four is the best outcome and total scores range from 0 (worst outcome) to 48 (best outcome)[5].

If there are more than two missing answers, it is recommended that the overall score should not be calculated. In the event one or two questions are unanswered, it is recommended that clinicians put in a mean answer from the patient's other answer, If a question has more than one answer, the worst response i.e. smallest number is used for calculations[5].

Equipment

Pen and paper, or online calculator.

Reference

Original article by Dawson et al 1998.

Useful information on background and use of The Oxford Knee Score by Oxford University Innovation.

Evidence

Reliability

The OKS has demonstrated strong test-retest reliability in its original testing[1]. A 2016 systematic review of 23 studies found good evidence of its reproducibility[6].

Validity

OKS shows significant correlation with similar measures (American Knee Society Score, SF-36, Health Assessment Questionnaire), particularly the pain and physical function domains[1]. A 2016 systematic review (23 studies) found good evidence for its internal consistency and construct validity[6].

Responsiveness

Research suggests the OKS is responsive to change post operatively [1][6] and a change of four or more points represents "real" change for an individual while a change of seven or more points represents "clinically relevant"[7].

Miscellaneous

Research[8] suggests that the OKS should not be used to decide whether or not an individual should have surgery because it can be biased in regards to gender, older age and to individuals reporting worse symptoms in order to meet criteria for surgery. Instead, the individual's pain symptoms should be used to determine surgery.

The OKS is available in available in multiple languages.

References

  1. 1.0 1.1 1.2 1.3 1.4 Dawson J, Fitzpatrick R, Murray D, Carr A. Questionnaire on the perceptions of patients about total knee replacement surgery. J. Bone Joint Surg 1998; 80-B:63-69. Accessed 15 January 2020.
  2. Murray D, Rogers K, Pandit H, Beard D, Carr A, Dawson, J. The use of the Oxford Hip and Knee Scores. The Journal of Bone and Joint Surgery. 2007. 89; 8: 1010-4. Accessed 2 December 2019.
  3. Browne J, Lewsey L, Van Der Muelen J, Black N.  Report to the Department of Health. London, UK: London School of Hygiene & Tropical Medicine; 2007. Patient Reported Outcome Measures (PROMS) in Elective Surgery.
  4. Rothwell A, Hooper G, Hobbs A, Frampton C. An analysis of the Oxford hip and knee scores and their relationship to early joint revision in the New Zealand Joint Registry. J Bone Joint Surg Br. 2010 Mar;92(3):413-8. Accessed 15 January 2020.
  5. 5.0 5.1 5.2 5.3 5.4 Oxford University Innovation. The Oxford Knee Score (OKS). 2016. Accessed online from https://innovation.ox.ac.uk/outcome-measures/oxford-knee-score-oks/ on 15 January 2020.
  6. 6.0 6.1 6.2 Harris K, Dawson J, Gibbons E, Lim C, Beard D, Fitzpatrick R, Price A. Systematic review of measurement properties of patient-reported outcome measures used in patients undergoing hip and knee arthroplasty. Patient Relat Outcome Meas. 2016; 7: 101–108. Published online 2016 Jul 25. doi: 10.2147/PROM.S97774. Accessed 15 January 2020.
  7. Beard D, Harris K, Dawson J, Doll H, Murray DW, Carr AJ, Price AJ. Meaningful changes for the Oxford hip and knee scores after joint replacement surgery. J Clin Epidemiol. 2015 Jan;68(1):73-9. doi: 10.1016/j.jclinepi.2014.08.009. Epub 2014 Oct 31. Accessed 15 January 2020.
  8. Robb C, McBryde C, Caddy S, Thomas A, Pynser P. Oxford scores as a triage tool for lower limb arthroplasty lead to discrimination and health inequalities. Ann R Coll Surg Engl (Suppl) 2013; 95. Accessed 15 January 2020.