Evaluating Psychometric Properties of the International Knee Documentation Committee Subjective Knee Form in a Heterogeneous Sample of Post-Operative Patients.
Ryan D Richardson, Madeline P Casanova, Ashley J Reeves and 3 others
PMID 37547827WHAT IT FOUND
Two short versions of the knee function questionnaire (6 and 8 items) track patient recovery as reliably as the original 18-item form.
They save time and work consistently across age and sex groups, allowing clinicians to measure true change after surgery.
Key findings
01The 6-item and 8-item short forms of the IKDC-SKF were highly correlated with the original 18-item score, meaning they capture most of the same information with far fewer questions.
02The 6-item and 8-item versions successfully measured statistically significant improvements in patient knee function and pain at 3, 6, and 12 months post-surgery, confirming they can track recovery over time.
03The short forms were stable across different age groups and sexes, allowing clinicians to validly compare scores between these patient subgroups.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study did not analyze patients over the age of 65 due to a small sample size, so the short forms are not yet validated for older adults. The data did not specify the exact knee pathology or surgical procedure, so it is unclear if the short forms work equally well for all types of knee problems. The internal consistency for the Activities of Daily Living (ADLs) construct in the 8-item version was 0.76, which is slightly below the preferred range of 0.80 to 0.90. The 9-item version failed longitudinal testing, meaning it cannot be used to reliably track change over time.
Declared interests
The authors declared no commercial or financial relationships. The study was supported by an Institutional Development Award from the National Institutes of Health.
The easy way to misread this
Do not assume the 9-item short form is safe for tracking progress over time; it failed longitudinal invariance testing because one item (about running) introduced bias. Use the 6-item or 8-item versions for measuring change.