Aim: By means of MR we have studied the
distribution of degenerative lesions in patients
with knee osteoarthritis (OA) in association
with work-related knee stress and
overweight to search for a typical pattern of
occupation-related knee OA.
Method: MR images of 114 symptomatic patients
(age 21–54) without history of traumatic
injury were evaluated with a modified wholeorgan
magnetic resonance imaging score
(WORMS). The study cohort was divided into
four groups based on the presence of the
risk factors overweight (cut-off BMI < 26) and
work-related knee stress (measured with the
Tegner score, work positions including kneeling,
squatting and climbing ladders).
Results: The WORMS for the whole knee joint
and the three joint compartments were increased
significantly and additively in the presence
of work-related knee stress and overweight
(p < 0.002). The degree of degeneration
was evenly distributed between the medial
(MP) and lateral (LP) patellar joint surface
in both overweight and normal weight patients
without work-related knee stress. Occupation-
related joint load was associated with
a significantly increased difference MP-LP
(ANOVA a priori contrast –1/1/–1/1, p = 0.001)
and a higher WORMS for the medial patellofemoral
joint (p = 0.002), compared with controls.
Evenly distributed or more lateral patellofemoral
degeneration showed a negative
predictive value of 80 % for the exclusion
of relevant occupation-related joint stress.
Conclusions: WORMS is a useful tool for evaluating
patterns of degeneration in work-related
knee OA. A higher WORMS on the medial
patellofemoral joint surface is an indicator of
occupational knee stress in both normal weight
and overweight patients. Joint derangement
in patients with occupational knee stress and
excess weight affects all joint compartments.
