Modification and validation of the Lysholm Knee Scale to assess articular cartilage damage.
OBJECTIVE
The Lysholm Knee Scale is an 8-item questionnaire originally designed as an outcome measure for ligament reconstruction but is commonly used as a measure for knee chondral damage. This study tests the scale's internal construct validity using the Rasch model, a measurement model which sets strict standards for the quality of measurement derived from the scale. The study also investigates the level of agreement between scores from patients and physiotherapists; and reviews the present weighting system.


METHODS
One hundred and fifty-seven patients with knee chondral damage awaiting surgery completed the Lysholm as part of a multicentre clinical trial based in 16 UK and two Norwegian hospitals. The patients were assessed by a physiotherapist who independently completed the Lysholm on the same day.


RESULTS
Fit to the Rasch model was achieved [mean item fit -0.26, standard deviation (SD) 1.01] after removal of one item (Swelling). With no differential item functioning (DIF) by rater, the intraclass correlation coefficient was 0.9 [95% confidence interval (CI): 0.86-0.93] and a Bland-Altman plot showed no consistent difference in rating.


CONCLUSIONS
The Lysholm Knee Scale satisfies Rasch model expectations after removal of the swelling item. Generally there is a high degree of agreement between the patient and professional ratings. By removing the swelling item and using unweighted scores, a modified version of the Lysholm Knee Scale is recommended as an outcome measure for knee chondral damage.
Smith
H J
HJ
Arthritis Research Centre, RJAH Orthopaedic Hospital NHS Trust, Gobowen, Oswestry, Shropshire, UK. heatherj.smith@rjah.nhs.uk
Richardson
J B
JB
Tennant
A
A
D000293:Adolescent; D000328:Adult; D002358:Cartilage, Articular / Q000293:injuries*; D019902:Chondrocytes / Q000637:transplantation; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010147:Pain Measurement / Q000379:methods; D011594:Psychometrics; D015599:Trauma Severity Indices; D016896:Treatment Outcome; D055815:Young Adult