Research Methods and Progress of Patellofemoral Joint Kinematics: A Review

Abstract

Patellofemoral pain syndrome has a high morbidity, and its pathology is closely associated with patellofemoral joint kinematics. A series of in vivo and in vitro studies have been conducted to explore patellofemoral kinematics, and the findings are relevant to the diagnosis, classification, and management of patellofemoral diseases and even the whole knee joint. However, no definite conclusion on normal patellofemoral kinematics has been established. In this study, the measurement methodologies of patellofemoral kinematics (including data collection methods, loading conditions, and coordinate system) as well as their advantages and limitations were reviewed. Motion characteristics of the patella were analyzed. During knee flexion, the patellar flexion angle lagged by 30–40% compared to the tibiofemoral joint flexion. The patella tilts, rotates, and shifts medially in the initial stage of knee flexion and subsequently tilts, rotates, and shifts laterally. The finite patellar helical axis fluctuates near the femoral transepicondylar axis or posterior condylar axis. Moreover, factors affecting kinematics, such as morphology of the trochlear groove, soft tissue balance, and tibiofemoral motion, were analyzed. At the initial period of flexion, soft tissues play a vital role in adjusting patellar tracking, and during further flexion, the status of the patella is determined by the morphology of the trochlear groove and patellar facet. Our findings could increase our understanding of patellofemoral kinematics and can help to guide the operation plan for patients with patellofemoral pain syndrome.

A Word of Caution for Future Studies in Patellofemoral Pain: A Systematic Review With Meta-analysis

“…This systematic review expands our clinical and research understanding regarding the origin of PFP, by providing quantitative evidence of the specific confounding variables’ influence, or lack thereof, on our ability to distinguish patellofemoral kinematics measured in patients with PFP from the kinematics measured in asymptomatic controls. This sets it apart from past reviews that attempted to generate a normative patellofemoral kinematic profile across studies 30,79 or sought to define which factors are most associated with patellofemoral pain (eg, sulcus angle, tibiofemoral alignment, bisect offset). 13,34 Irrespective of interstudy differences, this review presents strong evidence that lateral patellar shift and tilt maltracking are significantly associated with PFP_iso and PFP_dis.…”

“…Data from all studies in the final database were extracted and tabulated. The potential sources of intra- and interstudy variability 30,79 were identified during data extraction. These sources fell into 3 main categories: demographics, study design, and outcome measurement techniques.…”

“…The divergent patellar maltracking results likely arise from methodological differences across studies, 30,79 including differences in patient characteristics (eg, age, comorbidities, sex), activities studied (eg, open vs closed chain exercise), image analysis techniques (eg, dynamic magnetic resonance imaging, static radiographs), and outcome measures selected to represent patellofemoral kinematics (eg, congruence angle vs lateral patellar displacement). Based on these methodological differences, comparisons among studies are typically confined to general qualitative discussions, leaving us unable to generate a universal quantitative definition of patellar maltracking in PFP.…”

Relationship between patellofemoral finite helical axis and femoral trans-epicondylar axis using a static magnetic resonance-based methodology

“…Patellar maltracking is a common concern in the management of patellofemoral disorders [3,4]. However, high dependence on the coordinate system of patellar tracking leads to ambiguity in the consensus of the definition of normal tracking [5,6], and therefore is not accurate enough when evaluating patellofemoral kinematics with patellar tracking.…”

Relationship Between Patellofemoral Finite Helical Axis and Femoral Trans-Epicondyle Axis Using a Static Magnetic Resonance-Based Methodology

“…If focus merely on patellar tracking, there could be some inevitable disadvantages. High dependence on the coordinate system of patellar tracking has made the comparison among research results difficult, which led to the ambiguity to consensus of normal patellar tracking [4,5]. To deal with patellofemoral disorders, it is crucial to fully understand the in vivo patellofemoral kinematics.…”