By Emily Delzell
Medial cartilage damage, not lateral damage, is the more prevalent pattern of cartilage morphology in patellofemoral knee osteoarthritis in all but the most severely involved knees, according to research from Boston University School of Medicine.
The Massachusetts investigators assessed databases from three large OA studies of older adults (the Boston Osteoarthritis of the Knee, Framingham Osteoarthritis, and Multicenter Osteoarthritis studies) to determine the prevalence of medial versus lateral patellofemoral damage as well as the relationship of cartilage damage to knee alignment. Varus and valgus alignments were defined as being more than 2° from neutral.
In all studies the prevalence of medial patellofemoral damage was higher than that of lateral damage in all but the most severely involved knees. Surprisingly, this pattern was true regardless of knee alignment, even though valgus alignment is typically thought to be associated with lateral loading. Prevalence of lateral patellofemoral damage equaled or exceeded that of medial damage only in the most severely involved valgus knees.
The findings were e-published last month by Annals of the Rheumatic Diseases.
Gross KD, Niu J, Stefanik JJ, et al. Breaking the law of valgus: the surprising and unexplained prevalence of medial patellofemoral cartilage damage. Ann Rheum Dis 2012 Apr 25. [Epub ahead of print.]