High frequency of meniscal hypertrophy in persons with advanced varus knee osteoarthritis.

To examine the morphological changes of the medial meniscus in advanced knee osteoarthritis (OA) we examined 167 knee joints of 106 patients who subsequently underwent total knee joint arthroplasty from January to May, 2007. All 106 patients were females and their ages ranged from 57 to 83 years (mean 68.7 +/- 5.6 years). For patients with complete loss of medial joint space by weight-bearing radiography, the meniscal position was assessed by measuring meniscal subluxation and meniscal height. Meniscal morphology was assessed using a modified WORMS MRI-based method. Description of the prevalence of different meniscal morphologies and their respective positions are presented. The predominant type (32.2, 64.1 and 83.8% in anterior horn, mid-body and posterior horn, respectively) of meniscal morphology abnormality was a hypertrophied displaced tear. Medial meniscus height was found to be higher than lateral meniscus height. In persons with an hypertrophied meniscus the height of the medial meniscus was 8.06 +/- 1.15, 10.03 +/- 1.79, and 8.61 +/- 1.57 mm at anterior horn, mid-body and posterior horn, respectively, compared to those in other categories whose height was 6.04 +/- 0.92, 5.08 +/- 1.68 and 6.43 +/- 1.26 mm. A large proportion of persons with end stage varus knee OA have a paradoxically hypertrophied medial meniscus. This new finding of hypertrophied menisci highlights that not all menisci in persons with end stage OA are macerated or destroyed.