Knee Articular Cartilage Development in Children: A Longitudinal Study of the Effect of Sex, Growth, Body Composition, and Physical Activity

Abstract

The aim of this study was to describe the effect of sex, growth, Tanner stage, and physical activity on knee articular cartilage volume development. A total of 74 randomly selected male and female children aged 9 -18 y were measured on two occasions at an average interval of 1.6 y (range 1.3-1.9). Articular cartilage volume was determined at the patella, medial tibial, and lateral tibial compartments by processing images acquired in the sagittal plane using T1-weighted fat saturation magnetic resonance. Height, weight, and BMI were measured while Tanner stage and physical activity were assessed by questionnaire. Articular cartilage volume increased at all sites peaking in Tanner stage two. Males gained articular cartilage faster than females at all sites (patella ϩ233 L/y, 95% CI Ϫ7, ϩ473, medial tibial ϩ350 L/y, 95% CI ϩ118, ϩ582, lateral tibial ϩ256 L/y, 95% CI ϩ22, ϩ488). In both sexes, articular cartilage volume accrual at tibial but not patella sites correlated significantly with height change but not weight change. Overweight children did not differ significantly from normal children in articular cartilage volume either cross-sectionally or longitudinally. The most consistent physical activity association was with average intensity of sport with those above the median gaining approximately twice as much as those below the median at tibial (p Ͻ 0.05) but not patella sites. In conclusion, most children gain articular cartilage during growth, but there is wide variation in the amount of articular cartilage accrual. In particular, younger children, males, and those undertaking more vigorous sports have substantially higher accrual rates. These results provide novel data on articular cartilage development in humans. The long-term significance of these results with regard to osteoarthritis of the knee in later life remains hypothetical. Osteoarthritis (OA) is the major cause of disability in those over age 65 y (1). Risk factors such as genetic factors, sex, and body mass index have been identified for knee OA (2-4). However, much remains to be understood about this very common condition. There is convincing evidence that other diseases of later life such as ischemic heart disease, diabetes mellitus, and particularly osteoporosis are associated with childhood development (5, 6). Although there are no data in humans with regard to early life exposures and risk of osteoarthritis in later life, a study in senescent moose linked a higher incidence of osteoarthritis with a famine when the moose were weanlings (7). Defects in articular cartilage are widely considered to be the initial problem in osteoarthritis (8) although this viewpoint is not shared by all authors (9). However, articular cartilage development in humans is poorly understood. In part, this has been due to the lack of a noninvasive, accurate, in vivo assessment of articular cartilage. Recently, magnetic resonance imaging (MRI) has been shown to be a simple, safe, noninvasive, and reproducible technique for measuring knee articular cartilage thickness (...

Osteoarthritis, Exercise, and Knee Replacement: Figure 1.

“…The prevalence of radiographic OA was similarly lower in exercisers (20% vs 32%), as were total knee scores. Other studies have also reported similar findings 1,3,10,11 , suggesting a protective association of exercise for radiographic OA as well as disability. Importantly, we found very strong and statistically significant evidence for positive effects of exercise on disability ( Figure 1).…”

Knee Structural Alteration and BMI: A Cross‐sectional Study

“…While previous studies have reported that increasing BMI is positively associated with knee joint space narrowing in subjects with knee OA (2,26), there is no significant association between BMI and joint space area or width in normal knees (27). BMI was not associated with incident knee joint space narrowing (28) and the loss of knee cartilage volume in OA knees (19), and knee cartilage volume in overweight children did not differ significantly from that in normal children, either cross-sectionally or longitudinally (29). However, BMI has been inversely associated with tibial cartilage volume standardized for bone size (reflecting cartilage thickness) in men (21).…”

Effect of recreational physical activities on the development of knee osteoarthritis in older adults of different weights: The Framingham Study

“…Triathletes have thicker cartilage in their patellae, but thinner cartilage in their medial femoral condyles, than do agematched inactive study volunteers (6). In children, vigorous self-reported activity in the previous 2 weeks was associated with an accretion of cartilage compared with children with no reports of vigorous activity (7).…”