2023, Vol. 27 ›› Issue (13): 2099-2103

Knee rotation and patellar instability

Guo Zonglei1 , Wang Yehua2, Liu Guangluan1   

Abstract: BACKGROUND: Patellar instability is associated with a series of anatomical abnormalities of tibia, femur and soft tissue. The relationship between patellar instability and knee rotation is not well established.  
OBJECTIVE: To analyze the influential factors of knee rotation on patellar instability and the correlation between them.
METHODS: A total of 96 patients with knee osteoarthritis admitted to the Affiliated Hospital of Xuzhou Medical University from September 2018 to November 2021 were included. The image data of knee joint three-dimensional CT and patella (merchant position) X-ray film were collected. The correlation between knee rotation and patellar instability was analyzed by measuring the imaging parameters such as proximal tibia rotation, distal femur rotation, knee rotation, patellar tilt angle, and lateral patellar displacement distance.  
RESULTS AND CONCLUSION: (1) Pearson’s correlation analysis showed that knee rotation was moderately correlated with patellar tilt angle (R=0.440, P < 0.001) and lateral patellar displacement distance (R=0.453, P < 0.001). With the increase of knee external rotation, both patellar tilt angle and lateral patellar displacement distance increased. Proximal tibial rotation was strongly correlated with patellar tilt angle (R=0.578, P < 0.001) and lateral patellar displacement distance (R=0.654, P < 0.001). With the increased external rotation of proximal tibia, the patellar tilt angle and lateral patellar displacement distance increased. There was no correlation of distal femoral rotation with patellar tilt angle and lateral patellar displacement distance. (2) These findings indicate that in imaging findings, the lateral patellar displacement distance is less affected by knee rotation than the patellar tilt angle. The proximal tibial rotation was strongly correlated with knee rotation. The rotation of the knee joint was mainly affected by the proximal tibial rotation, while the distal femur rotation was not correlated with the rotation of the knee joint.
Key words: knee osteoarthritis, knee rotation, proximal tibia rotation, distal femur rotation, patellar instability, patellar tilt angle