To explore the rule and influencing factors of knee joint line remodeling as well as non-uniform settlement through measuring basic parameters of X-ray in patients with knee osteoarthritis (KOA).

A retrospective study was done in148 patients (total 192 knees) treated in China–Japan Union Hospital of Jilin University from January 2015 to December 2016, including 50 males (59 knees) and 98 females (133 knees). Aged from 41 to 81 years with a mean age of 64±9 years. Patients were divided into <60 years Group and ≥60 years Group. All knee joints were classified by K-L grade. The distance between the knee anatomical landmarks and the knee joint, the altitude of femoral condyle and tibial platform were first measured and then analyzed on a standard knee anteroposterior radiograph.

The distances from femoral adductor tubercle and the apex of fibular head to knee line were (50±5) mm (ATJL) and (17±5) mm (FHJL), respectively. The altitudes of medial and lateral femoral condyle, medial and lateral tibial plateau were (49±5) mm (MFCA), (47±6) mm (LFCA), (4±5) mm (MTPA) and (9±4) mm (LTPA), respectively. The femoral width (FW) was (93±7) mm which was positively correlated with ATJL (r=0.651, P<0.001). The differences of FW, ATJL, MFCA, LFCA in gender were statistically significant (P<0.05). There was statistically different in MTPA between two different age groups (t=2.195, P=0.003). According to the K-L grade, there existed statistically significant difference between two groups (F=4.082, P=0.003), and MTPA was negatively correlated with the K-L grade (r=-0.241, P=0.001).

The MTPA is negatively correlated with the severity of KOA, which can be used to evaluate the severity of KOA. There was a correlation between ATJL and FW in KOA patients. The height of the lateral femoral condyle and lateral tibial plateau did not change significantly with increased age, and the height of medial tibial plateau decreased significantly, suggesting non-uniform settlement of tibial plateau with age.