High systemic bone mineral density increases the risk of incident knee OA and joint space narrowing, but not radiographic progression of existing knee OA: the MOST study

Abstract

Objectives Previous studies suggest that high systemic bone mineral density (BMD) is associated with incident knee OA defined by osteophytes, but not with joint space narrowing (JSN), and are inconsistent regarding BMD and progression of existing OA. We tested the association of BMD with incident and progressive tibiofemoral OA in a large, prospective study of men and women ages 50–79 with, or at risk for, knee OA. Methods Baseline and 30-month weight-bearing PA and lateral knee x-rays were scored for K–L grade, JSN and osteophytes. Incident OA was defined as the development of K–L grade ≥2 at follow-up. All knees were classified for increases in grade of JSN and osteophytes from baseline. The association of gender-specific quartiles of baseline BMD with risk of incident and progressive OA was analyzed using logistic regression, adjusting for covariates. Results The mean age of 1,754 subjects was 63.2 (SD, 7.8) and BMI 29.9 (SD, 5.4). In knees without baseline OA, higher femoral neck and whole body BMD were associated with an increased risk of incident OA and increases in grade of JSN and osteophytes (p < 0.01 for trends); adjusted odds were 2.3 to 2.9-fold greater in the highest vs. the lowest BMD quartiles. In knees with existing OA, progression was not significantly related to BMD. Conclusions In knees without OA, higher systemic BMD was associated with a greater risk of the onset of JSN and K–L grade ≥2. The role of systemic BMD in early knee OA pathogenesis warrants further investigation.

Osteoarthritis and bone mineral density: are strong bones bad for joints?

“…17 Although the populations studied have been predominantly female, there is also evidence of a positive association between BMD and incident knee OA in male populations. 19,20 A similar association between higher BMD and incident radiographic hip OA has been reported in postmenopausal women, 21 whereas Sowers et al 16 found no evidence of a longitudinal association with hand OA in a population of pre-and peri-menopausal women.…”

“…Hart et al 18 also observed a trend towards lower hip BMD in those with progressive knee OA versus non-progressors. In contrast, Nevitt et al 19 failed to find any association between BMD at the femoral neck or whole body and knee OA progression. If an inverse association between BMD and OA progression does hold true, it may provide important insights into the role of bone in the pathogenesis of OA at different stages of the disease.…”

“…7,17,18,21 Indeed, only one longitudinal study to date has convincingly demonstrated a positive association between BMD and incident JSN at the knee. 19 Several possible explanations for this observation, both methodological and biological, can be postulated. A stronger association with osteophytes in this type of study may arise because radiographs are insensitive for the detection of JSN.…”

“…7,10 More recently, the temporal relationship between BMD and OA has been clarified in prospective studies ( Table 2). Several longitudinal studies have shown higher BMD to be associated with a greater risk of developing subsequent radiographic knee OA, [16][17][18][19][20] although findings have not always been conclusive. 17 Although the populations studied have been predominantly female, there is also evidence of a positive association between BMD and incident knee OA in male populations.…”

Patients With Knee Osteoarthritis Have a Phenotype With Higher Bone Mass, Higher Fat Mass, and Lower Lean Body Mass

“…Again, this study can only show an association between knee OA and the studied variables, does not imply causation, and should therefore be regarded as hypothesis-generating. Studies suggest that OA and osteoporosis are distinct different diseases [9] and an association between OA in the hip, knee, ankle, and feet and a high BMD has also been found [3,4,6,8,13,17,20,23]. It has been speculated that a high BMD may result in a denser and stiffer skeleton with less load absorptive ability, a phenotype that may be involved in the pathogenesis of primary OA [25].…”