# Novel Technologies Used in the Assessment of Patellofemoral Pain: A Scoping Review
## 4 Discussion
### Imaging Studies  
Radiographic, CT, and MRI evaluations are commonly preferred for differential diagnosis of PFP [46]. Initially, anteroposterior and lateral radiographic imaging is involved for the evaluation since it is a simple and quick option to see the patellar position (patella alta, patella baja, lateromedial subluxation) for the first clinical diagnosis [7]. However, CT and MRI imaging have advantages over radiographic assessments since they provide static and dynamic cross-sectional scanning including soft tissues and information about other possible abnormalities [6; 7]. However, all of the imaging techniques offer dynamic evaluations, and all of them have advantages and disadvantages in terms of radiation exposure, acquisition quality, and time limitations [5; 47; 48; 49]. Imaging is often performed in the supine position in which the patella is simply not exposed to any muscle forces. However,PFP patients experience symptoms while the patella is exposed to muscle forces such as running and stair ascent and descent. Especially with the advancement in biomechanical analysis and improved understanding of patellar kinematics [30], acquisition techniques have become more specific and tailored by applying devices to create weight-bearing conditions. Thus, dynamic assessments have gained importance to provide a real-time interplay of soft tissue and bone structures. In the current review, there were 34 articles using imaging evaluations in weight-bearing and dynamic conditions. Thirty of these used standard MRI, CT, and other radiographic devices with custom-built loading platforms to apply forces at the patello-femoral joint. These platforms were mainly fixed under the feet and allowed the subject to push and release force in their muscles. So far, the technology was well known but the technique was different from static acquisition. However, two studies used CBCT, which is quite a breakthrough version of CT [23; 24]. CBCT is an emerging medical imaging technique forming a cone shape as opposed to the spiral slicing of conventional CT [13]. CBCT uses a rotating platform with a radiation emitter and flat panel detector to gather multiple quick exposures and produce a 3D volumetric image. By projecting a collimated beam with a large rotation around the stationary patient, a complete volumetric three-dimensional data-set is collected. This differs from traditional CT scans, which use a helical 2D fan shape, resulting in slower scanning times and higher radiation dosages. Exposure to less than half the radiation dosage compared to traditional CT has been noted for these foot and ankle scans [50]. CBCT also has less image distortion and fewer artifacts associated with patient movement [51]. This technique provides convenience by collecting the data very quickly, enables data collection in an up-right posture, and implies less radiation exposure. While up-right evaluation is particularly important for foot and ankle studies, these devices enable visualization and measures of the position of bones and muscles under physiological load, which is much better when compared to CT scans under simulated loading conditions. However, the cone-shaped beam causes scatter interference when radio-opaque materials, like metal, are in the anatomical area of interest. This interference significantly reduces the image quality [51]. Regarding the cost-effectiveness, it has been reported that the yearly mean profit can even be over EUR 53,000 in a typical hospital [52]. Also, it has been shown that using CBCT shortens the scanning time 77% per patient in the same study. One original article from this review used a novel instrument to test stress on the patella [25]. This instrument, known as the Porto Patellar testing device (PPTD), is safe and compatible for use within MRI/CT and is claimed to be reliable [26]. This polyurethane modular device provides stress on the medial facet of the patella by applying a lateral force vector, in case at different knee flexion angles.