Relation of Primary Knee Osteoarthritis with Bone Mineral Density in Postmenopausal Women
Abstract
Osteoarthritis and osteoporosis are two common age related musculoskeletal diseases, which are highly prevalent health problems in postmenopausal women associated with considerable morbidity. This study was conducted with the aim to find out the relation between knee osteoarthritis (OA) and bone mineral density (BMD) in the left femur of postmenopausal women. A total of 100 postmenopausal women were assessed and KL grading was done according to Kellgren–Lawrence criteria. The BMD of the subjects was measured using Dual-Energy X-ray Absorptiometry (DEXA) and classified using WHO criteria on basis of T score. It was found that out of 100 postmenopausal women 68% were in KL-2 grade in which 53% were osteopenic and 37% were osteoporotic. The significant negative correlation was observed between KL grading left knee and T score. So it can be concluded that primary OA knee in postmenopausal women is associated with decreased BMD. So, it is recommended that OA knee in postmenopausal women should be evaluated for BMD for further management of pain & prevention of complication of low bone mass.
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Introduction
Osteoarthritis and osteoporosis are two common musculoskeletal diseases affecting millions of eldely people with high morbidity.1
Osteoarthritis has generally been considered as a cartilage disease characterized by slow progressive degeneration of articular cartilage due to “wear and tear” mechanisms. This disease impacts on all anatomical joint structures.2 It is characterized by joint pain and stiffness, cartilage degeneration, thickening of subchondral bone, loss of joint function and reduction in mobility.2
The etiology of osteoarthritis is multifactorial and it can affect both weight bearing and non weight bearing joints. It is initiated as a result of mechanical, structural, genetic and environmental factors.
Osteoporosis consist of heterogeneous group of syndromes in which bone mass per unit volume is reduced in healthy bone, resulting in fragile bone, this increment of bone porosity results in instability of bone and increase likelihood of fracture. Fractures, chronic pain, disability and decreased bone mineral density are major symptoms of Osteoporosis.3 Postmenopausal women are susceptible to primary osteoporosis since osteoporosis is closely related to estrogen deficiency.4
WHO operationally defines osteoporosis as bone density that falls 2.5 SD below the mean for young healthy adults of same gender (T score less than or equal 2.5). 5 The life time risk of an osteoporotic fracture to be 40-50% in women and 13-22% in men are associated with substantial morbidity and a significantly increased mortality risk.6
Conclusion
In the present study, the bone mineral density of proximal femur of left hip was negatively correlated (r=-0.262 poor correlation p value=0.009) with left knee osteoarthritis and T score of BMD was also found negatively correlated (r=-0.243 p=0.015). It is recommended that OA knee in postmenopausal women should be evaluated for BMD for further management of pain & prevention of complication of low bone mass.