Symptomatic knee disorders measured by The Knee Injury and Osteoarthritis Outcome Score KOOS in floor layers and graphic designers

Introduction
The aim of this study has been to evaluate symptomatic knee disorders among floor layers compared to graphic designers using The Knee Injury and Osteoarthritis Outcome Score KOOS, and relate the KOOS results to self-reported knee complaints, radiological knee osteoarthritis; kneeOA, and MRI detected meniscal tears and bursitis.

Methods
134 floor layers and 120 graphic designers (referents) were examined with X-ray of both knee joints, and of those 92 floor layers and 49 graphic designers also had a magnetic resonance imaging; MRI of both knees. The Knee Injury and Osteoarthritis outcome score, KOOS was used to quantify knee-related symptoms. The score includes 5 separate subscales: Pain, other Symptoms, and Function of Daily Living (ADL), function in sport and recreation, and knee-related Quality of Life (QOL). Height, weight, knee-loading sports activity was collected by questionnaires. Analyses were carried out by using Chi-square test and binary logistic regression analysis, and adjusted for BMI, knee-loading sports, and knee traumas.

Results
Floor layers scored significant higher on all KOOS subscales compared to graphic designers. There is a correlation between high scores on KOOS-subscales and self-reported current knee pain regardless of trade. There are significant differences in scores on KOOS-scales for subjects with and without kneeOA. Subjects with radiological kneeOA grade 1-3 showed no differences in scores on KOOS comparing floor layers and graphic designers. KOOS-subscales are in general low among floor layers and graphic designers who have been diagnosed with bursitis or meniscal tears.

Discussion
There is a good correlation between knee symptoms measured by KOOS, radiological detected kneeOA, and self-reported symptoms in this study. There are no differences in KOOS comparing floor layers and graphic designers with knee complaints or radiological detected kneeOA. KOOS may be appropriate describing symptomatic knee disorders in occupational epidemiological studies.