Dynamic Evaluation of Patellofemoral Instability: A Clinical Reality or Just a Research Field? A Literature review

Abstract

Patellofemoral instability (PFI) is one of the most disabling conditions in the knee, often affecting young individuals. Despite its not uncommon presentation, the underlying biomechanical features leading to this entity are not entirely understood. The suitability of classic physical examination manoeuvres and imaging tests is a matter of discussion among treating surgeons, and so are the findings provided by these means. A potential cause for this lack of consensus is the fact that, classically, the diagnostic approach for PFI has relied on statically obtained data. Many authors advocate for the study of this entity in a dynamic scenario, closer to the actual situation in which the instability episodes occur. In this literature review, we have compiled the available data from the last decades regarding dynamic evaluation methods for PFI and related conditions. Several categories are presented, grouping the related techniques and devices: physical examination, imaging modalities (ultrasound (US), magnetic resonance imaging (MRI), computed tomography (CT) and combined methods), arthroscopic evaluation, and others. In conclusion, although a vast number of quality studies are presented, in which comprehensive data about the biomechanics of the patellofemoral joint (PFJ) are described, this evidence has not yet reached clinical practice universally. Most of the data still stays in the research field and is seldom employed to assist a better understanding of the PFI cases and their ideal treatment targets.

Clinical Outcomes and Prognostic Factors in Patients With Recurrent Patellar Lateral Dislocation Treated With Isolated Medial Patellofemoral Ligament Reconstruction: A Retrospective Single-Center Analysis

“…17 Nevertheless, the focus of the present study was to explore other potential factors that may influence the outcomes of isolated MPFLR rather than the technique per se. Fourth, the stability of the patella and knee function depend on static and dynamic structures 28 -for example, the quadriceps, especially the internal oblique muscle. The study did not take this factor into consideration.…”

Patellar Instability

“…Although both TT-TG and TT-PCL can be used to assess patellar alignment, an increased TT-PCL value represents true tibial tubercle lateralization 33 . In addition to dynamic CT 35 , dynamic MRI may be used to assess patellar maltracking. A recent study found that in patients with maltracking, a greater degree of mediolateral translation (12.4 ± 6.9 mm vs. −0.1 ± 2.3 mm) and a more lateral position of the patella were present compared with controls.…”

Fully automatic extraction of knee kinematics from dynamic CT imaging; normative tibiofemoral and patellofemoral kinematics of 100 healthy volunteers

“…In order to diagnose subject-specific knee kinematics and pathologies, several in-vivo dynamic imaging techniques of the knee joint have been developed using a variety of different modalities such as MRI, Fluoroscopy, CT or a combination of these techniques [1,2]. In these studies various loading conditions and dynamic tasks were investigated [3][4][5][6].…”

“…In two comprehensive review studies, the current state of dynamic imaging for the patellofemoral joint was studied [2,8]. Both review studies conclude that dynamic imaging provides valuable insight into knee kinematics and pathologies and underline the need for objective and accurate determination of subject-specific knee kinematics.…”