# Novel Technologies Used in the Assessment of Patellofemoral Pain: A Scoping Review
## 1 Introduction  
Patellofemoral pain (PFP) is a common clinical condition especially in the young active population. It refers to pain during activities behind or around the patella and has a gradual onset with increased frequency or duration [1]. The literature for PFP reports concerns for the high incidence, prevalence numbers, disability levels, and poor prognosis [2, 3]. Diagnosis of PFP relies mainly on clinical examination and imaging. Differential diagnosis is key to separate it from other possible causes of pain such as osteoarthritis and chondormalacia patellae. However, since it is a syndrome with unclear pathogenesis and still-debated biomechanics, understanding the causative reasons and clinical characteristics is a challenge for health professionals [4, 5].  
Associated with the large general developments of the technology, studies using state-of-the-art instruments and techniques, also during execution of daily living motor tasks,are growing rapidly by examining PFP patients through kinematic and kinetic analyses, imaging technologies, electromyography (EMG), isokinetics, etc. Unfortunately, results gathered from imaging and assessment measures can hardly be merged or compared, because of different factors, such as the reliability of instruments, real-life adaptability of the measure (i.e., somehow predictability of real-life conditions), and the large spectrum of variables [6; 7]. Due to these conflicts, manufacturers focused on developing new technologies to solve the inconsistency in the results and also tried to consider the issues such as cost-effectiveness, fewer side-effects, and practical use. Despite the heterogeneity of the technologies used, a number of studies have recently examined possible innovative technologies, also evaluating their cost-effectiveness, and pros and cons [8; 9; 10]. These studies have highlighted the relevance of technological innovations in musculoskeletal rehabilitation and their potential to improve the sustainability of healthcare systems for the assessment and management of general patients.  
Although measures from medical imaging in static conditions definitely provide valuable information, functional assessments during motor tasks can also provide observations from daily living and in real-time, thus giving access to the dynamic interactions of hard and soft tissues [5; 7]. This has been reported in a number of studies using gait analysis and biomechanical modeling [11; 12]. Now, medical imaging in dynamic and weight-bearing conditions also in 3D are accessible [13; 14; 15] for these assessments. However, technical experience must become more mature, and costs, radiation, access to these instruments, data post-processing, etc., are known concerns that limit current relevant exploitations [7]. Bi-dimensional analyses are still frequently used, such as those for the frontal plane projection angle [16] and the Q-angle, but modern instrumented gait analysis provides thorough 3D dynamic measurements of joint kinematics and kinetics [17; 18], in real-time and also synchronized with surface EMG.  
The abovementioned technological innovations have led us to wonder whether they are used and whether any other technologies are currently used in people with PFP. Therefore, this review aims to present the existing evidence from the literature of novel technologies developed in the last decade to assess PFP, with a particular focus on the patellar area to avoid indirect assessments to the joint. As the intention was to provide existing evidence, the option was to conduct a scoping review to address what we already have in the heterogeneous literature as aimed in the scoping review methodologies. Also, the context of these novel assessments and the possible further directions are discussed.