In vivo measurements of patellar tracking and finite helical axis using a static magnetic resonance based methodology

Characterization of patellar maltracking using dynamic kinematic CT imaging in patients with patellar instability

“…Using this system, 79 % of those with a grade-2 J sign and 93 % of those with a grade-3 J sign had symptoms of patellar instability, indicating that more than two quadrants of lateral patellar translation during active extension may be a positive indicator for symptomatic patellar instability. A recent study by Yao et al [17] attempted to quantify patellar tracking by correlating patellar position with knee flexion angles. The authors studied MRI at 0°, 45°, 60°, 90°, and 120° of knee flexion on a single control patient.…”

Research Methods and Progress of Patellofemoral Joint Kinematics: A Review

“…Imaging methods, including ultrasound [16–18], X-ray [19], computed tomography (CT) [20–24], single- and biplane fluoroscopy [25–27], and magnetic resonance (MR) imaging [28–35], have been used for in vivo measurements. With the advantages of noninvasive, radiation-free acquisition, and soft tissue contrast, MR imaging has been widely applied to the research on patellofemoral kinematics [28, 31, 32, 34, 35]. After the MR scannings of the joint, femur and patella were segmented and reconstructed to 3D models.…”

“…Patellar maltracking may appear at diverse ranges of knee flexion, yet the knee flexion angles of the previous studies were often less than 60° due to the limitation of the field of view in CT and MR machines. With the imaging devices being optimized, the knee flexion range captured in the recent studies has been increased to greater than 90° [31, 32], which could contribute to a more comprehensive understanding of patellofemoral joint biomechanics.…”

“…Loading conditions (e.g., weight-bearing loading and quadriceps force) could influence the results of patellar tracking measurements. Researches have explored the patellar tracking with different weight-bearing loadings [16, 22, 29–32, 37, 38, 46]. Non- and full-weight-bearing loadings could be achieved by sitting and standing.…”

“…Moreover, the femoral groove axis has been used occasionally, despite the difficulty in fitting the curving trochlear groove into a straight line [47]. Because of less variation in the medial and lateral epicondyles, as well as the posterior condyles among different individuals, the TEA [17, 23, 30–32, 35, 37, 38, 40, 44] and posterior condylar line [32, 33, 36, 47] were often regarded as ML axis. The femoral AP axis can be established by the cross product of the longitudinal and ML axes [17, 19, 30].…”