Limb Alignment, Subluxation, and Bone Density Relationship in the Osteoarthritic Varus Knee

Abstract

Lower limb alignment, tibiofemoral (TF) subluxation, and bone density changes around the knee are significant factors related to the development of knee osteoarthritis (OA) and have great impact on its severity. The relation of each factor to knee OA was evaluated separately in previous studies; however, few studies have attempted to integrate their respective effects. The purpose of this study was to determine if an identifiable interaction exists between coronal limb alignment, TF subluxation, and bone density in the development of knee OA. A total of 120 patients with symptomatic, varus knee OA, with preoperative standing anteroposterior (AP) hip-to-ankle radiographs and a computed tomographic scan of the knee, were included in this study. Overall mechanical lower extremity alignment, and TF subluxation were measured on the AP radiographs, while trabecular bone density (TBD) was measured in four regions of interest for both the tibial plateau and distal femur in all patients. The patients were stratified into the following four cohorts: (A) high subluxation, high angulation; (B) high subluxation, low angulation; (C) low subluxation, high angulation; and (D) low subluxation, low angulation. The mean TBD in group B was significantly higher than in groups C and D (p = 0.003 and 0.03, respectively). In addition, the mean TBD in group A was significantly higher than in group C. This study highlights the relationship between limb alignment, knee subluxation, and bone density in the osteoarthritic knee. These preliminary results present a proof-of-principle, that bone mineral density affects the degree of coronal alignment and TF subluxation in OA.

Tibiofemoral subluxation in the coronal plane does not affect WOMAC and KOOS after total knee arthroplasty

“…Correctability of CTFS after opening wedge high tibial osteotomy and unicompartmental knee arthroplasty suggests that the development of tibiofemoral subluxation is associated with factors that cause ligamentous stability [2, 16]. In addition, higher bone mineral density around the knee was associated with a greater degree of severity of CTFS [8]. In our study, no significant correlation was observed between the degree of varus deformity and the amount of tibiofemoral subluxation.…”

“…Subluxation of the tibia relative to the femur in the coronal plane has been reported a common radiological finding in knee osteoarthritis (OA) [10]. Although CTFS is not an essential sign of knee OA, it is developed in the early stages of knee OA and is not considerably progressed in stiff and contracted knees [8]. There are conflicting results regarding the effect of CTFS on OA progression.…”

Cartilage survival of the knee strongly depends on malalignment: a survival analysis from the Osteoarthritis Initiative (OAI)

“…Not surprisingly, external subregions on the medial tibia and femur are affected early too and the shortest survival rate of the contralateral compartment was determined in the internal lateral tibia. This might be related to beginning medial subluxation [21, 22].…”

Osteoporosis is associated with varus deformity in postmenopausal women with knee osteoarthritis: a cross-sectional study

“…Therefore, the prevention of varus deformity can greatly delay the speed of joint degeneration, which is the key to prevent and treat severe KOA. It is well known that varus deformity may result from congenital anatomical abnormalities, or it may be secondary to medial articular space narrowing after cartilage wear and subluxation of the tibiofemoral joint [ 14 ]. However, this cannot fully account for all clinical varus deformity.…”