Relationship of lower limb geometrics with femorotibial osteoarthritis in the toei cohort

Osteoarthritis (OA) is a common disease of joints that is more common in females than in males. It is characterized by severe knee degeneration, damaged cartilage and appearance of osteophytes. Hip geometry and morphometric parameters in the knee joint vary between the sexes and depend on the severity of OA and the presence of osteophytes. Very few studies have assessed this phenomenon; therefore in this study, we assessed the difference in hip geometry and morphometric parameters in the lower limbs of males and females and evaluated the association of the differences with the presence or absence of osteophytes. Three hundred and six knees volunteers (104 male knees and 202 female knees) from the Toei region were included in the study between 2012 and 2018. The parameters measured were from the anteroposterior and lateral views of the hip and anteroposterior view of the knee. The participants were divided into 4 groups based on the assessment for osteophytes: Group 1 had no osteophytes, Group 2 had lateral compartment osteophytes, Group 3 had medial compartment osteophytes, and Group 4 had osteophytes in both compartments. Males had an increased femoral neck-shaft angle, femoral-tibial angle, and plateau angle, and a decreased femoral offset, femoral neck length, fibular-tibial angle, and knee rotation index than females. Group 2 had a greater height of the hip center, the angle between the femoral mechanical axis and the femoral shaft axis, condylar-hip angle, and plateau angle than Group 1. Group 3 showed an increased abductor angle, the angle between the femoral mechanical axis and the femoral shaft axis. Group 4 showed an increased angle between the femoral mechanical axis and the femoral shaft axis, femoral-tibial angle, and a decreased patellar shift index and knee rotation index. The angle between the femoral mechanical axis and the femoral shaft axis, condylar-hip angle, femoral-tibial angle, plateau angle, patellar shift index, and knee rotation index were different in both sexes and may be dependent on the presence or absence of osteophytes.