Study on Bone Mineral Density Around the Knee in Postmenopausal Women with Osteoarthritis and Osteoporosis

Osteoporosis (OP) and knee osteoarthritis (KOA) are common comorbidities in postmenopausal women, yet the relationship between OP and localized bone mineral density (BMD) around the knee remains unclear. This study investigated the effect of concomitant OP on periarticular BMD and its associations with the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), radiographic severity, and hip-knee-ankle (HKA) angle in postmenopausal women with KOA.

In this cross-sectional study, 117 postmenopausal women were classified into a KOA combined with OP group (n=59) and a KOA-only group (n=58) based on dual-energy X-ray absorptiometry (DXA) T-scores. All participants underwent dual-energy computed tomography (DECT) to quantify BMD around the distal femur, proximal tibia, and patella; weight-bearing radiographs to assess Kellgren-Lawrence (K&L) grade and HKA angle; and the WOMAC questionnaire to evaluate pain and joint function.

Patients with KOA combined with OP demonstrated significantly lower knee BMD than those with KOA alone (P < 0.001). This reduction in BMD was more pronounced with increasing OP severity. Notably, even after adjusting for pain levels, BMD remained significantly lower in the KOA combined with OP group (P < 0.05). Furthermore, medial knee BMD in the KOA combined with OP group exhibited an inverted U-shaped relationship with K&L grade, peaking at grade III before declining. In contrast, BMD increased progressively with K&L grade in the KOA group. A significant inverse correlation was also observed between the HKA angle and medial knee BMD in the KOA combined with OP group, suggesting greater bone loss with increasing valgus deformity.

Postmenopausal women with KOA combined with OP have markedly lower periarticular BMD, associated with more severe pain, distinctive radiographic changes, and poorer alignment. These findings highlight the need for active bone preservation and OP management in KOA patients to alleviate symptoms and potentially slow disease progression.