Patellar tracking patterns during active and passive knee extension: evaluation with motion-triggered cine MR imaging.

Abstract

To evaluate the critical range of the patellofemoral joint motion from 30 degrees of knee flexion to full extension, motion-triggered cine magnetic resonance (MR) imaging was performed during active extension in 13 patients with confirmed patellar maltracking and 15 healthy subjects. Cine MR images were compared with static MR images obtained during incremental extension of the knee joint. To evaluate the patellar tracking pattern, the same imaging parameters (patellar tilt angle, bisect offset, and lateral patellar displacement) and section locations were used in the static and motion-triggered studies. Statistically significant differences between the passive and active knee motions were found in all three parameters in the group of patients and in the bisect offset in the control group. The comparison between patients and healthy subjects yielded statistically significant differences for all parameters in actively extended knees but not in passively extended knees. The results demonstrate the importance of dynamic patellar motion studies for diagnosis of patello-femoral maltracking.

Quantitative analysis of dynamic patellar tracking in patients with lateral patellar instability using a simple video system

“…The patella positioned more laterally at 0° than 30° of knee flexion and the displacement in patients was significantly larger than that of controls. After the first report, patellar tracking pattern during active knee extension using various measurement systems such as MRI, ultrasound under various conditions was investigated [11][12][13][14][15][16][17][18][19][20][21]. Our result that patellar tracking in patients with patellar dislocation was significantly larger than that of controls at lower knee flexion angle, in agreement with the previous reports.…”

“…However, the radiation exposure is invasive to subjects and the measurements are acquired only under static conditions at limited knee flexion angles. On the other hand, various methods for quantitative evaluation of dynamic patellar tracking have been projected in previous studies; such as with custom-made devices for cadaveric specimens [11][12][13], dynamic CT [14], open MRI [15][16][17][18][19], ultrasound transducer [20] and optoelectronic motion capture [21]. However, open MRI and these original measurement systems require special facilities and equipments, and take much cost and time.…”

Standardisation of the description of patellofemoral motion and comparison between different techniques

“…If the increments of position are small enough, then the description of motion may be acceptable. Patellar positions measured 'statically' may be different to those found 'dynamically', due to differences in muscle activity [4], and other factors such as direction of travel [14]. The exact rôle of speed of knee joint flexion-extension is undefined.…”

“…For the past ten years kinematic CT and MRI have been used to investigate the patellar motion during dynamic knee joint movement [4,22,27]. A significant drawback of the imaging studies has been the inability to describe the patellar motion in 3-dimensional space.…”

Precise 3D skeletal kinematics using fast phase contrast magnetic resonance imaging

“…In addition, few studies have investigated the complete knee joint (patello-tibio-femoral joint), opting to study the patellofemoral or the tibiofemoral joint in isolation. Lastly, these joints have been studied under static (5-7), quasi-static (8 -10), or dynamic (11)(12)(13)(14)(15)(16)(17) conditions; in two and three dimensions; in healthy subjects, in patients with specific impairments and using cadavers. Such variety in experimental protocols leads to confusion when trying to establish baseline levels for healthy and impaired joint function.…”