Radiographic measures of settlement phenomenon in patients with medial compartment knee osteoarthritis

In this study, we proposed for the first time the theory of "settlement phenomenon" in tibial plateau and carefully explored the role of settlement of tibial plateau in the occurrence and progression of medial compartment knee osteoarthritis (OA) through investigating the relationship between the degree of settlement and the radiographic severity of OA. One hundred twenty-seven patients with knee medial compartment OA were recruited and examined with weight-bearing radiographs of the entire lower limb. The radiographic severity of OA was evaluated using the Kellgren and Lawrence (KL) grading methods. The settlement value, hip-knee-ankle angle, minimum medial joint space width, and condylar plateau angle were measured at the same time. The settlement value increases with the upgrading of KL grades (r = 0.352, P < 0.001) and is significantly correlated with the changes of hip-knee-ankle angle, minimum medial joint space width, and condylar plateau angle (r = -0.527, -0.271, and 0.415, P < 0.001, respectively). These results suggest that the settlement of tibial plateau could be an evaluable indicator of medial compartment knee OA and be used in the early diagnosis and progression of OA.