AB1135 ECHO-ANATOMY OF THE PROXIMAL TIBIOFIBULAR JOINT
Authors: M. C. Trojani, B. Le Goff
Journal: Annals of the Rheumatic Diseases (2020)

Background: The proximal tibiofibular joint (PFTJ) should be considered in the differential diagnosis of a patient presenting with complaints in the lateral aspect of the knee However, this joint is often forgotten, yet involved in many degenerative and inflammatory pathological processes. MRI remains the imaging of choice to study the PFTJ. Ultrasound could also be useful in clinical practice to study the joint and its environment. To our knowledge, there is no systematic descriptive echo-anatomical study of PFTJ that would allow to standardize the ultrasound scanning of this joint. Objectives: The objective of our study was to describe standardized ultrasonographic scans of the PTF joint and its environment starting from an anatomical study of the joint and then confirming the visibility of the different structures on a series of healthy volunteers. Methods: We first conducted an anatomical study of the PTFJ on 3 cadavers. The different part of the joint (capsule, cartilage, ligaments) and the environment (nerves, muscles, vessels) were studied allowing an exact correlation between US images and the structures. This step led us to choose 3 scans useful for the study of the different part of the joint in clinical practice (figure 1): an anterior transverse oblique, a strict coronal, and a posterior transverse oblique. Subsequently, a TFPJ ultrasound was performed on 20 healthy volunteer patients to evaluate the feasibility and the visibility of the different structures seen on the dissection part. Figure 1. Results: The different structures seen on the anterior transverse oblique scan were the anterior joint space, cartilage and anterior proximal tibiofibular ligament. The coronal approach led us to the visualization of the joint space, the collateral lateral ligament, the inferolateral genicular and posterior tibial recurrent artery, the meniscus and more posteriorly the ligaments of the posterolateral corner (popliteofibular, arcuate and fabellofibular). Finally, the posterior transverse oblique allowed us to study the posterior ligaments and joint recess under the soleus muscle. Twenty healthy volunteers with an average age of 29 years underwent an ultrasound of the right PTF joint. The joint line spacing was visualized in 100% of the cases on the 3 sections. The anterior cross-section allowed anterior proximal tibiofibular ligament analysis in 100% of the cases (median length 15,7 mm (min-max: 12.3 – 23.4), median thickness 1.4 mm (min-max: 1-2.3). The coronal section allowed identification of the inferolateral geniculate and posterior tibial recurrent arteries in 90 and 85% of cases respectively, and the distal insertion of the fibular collateral ligament in 100% of cases. Posterior sectioning was more challenging and identification of the popliteal tendon, arcuate ligament and posterior proximal tibiofibular ligament was possible in 16, 7 and 2 patients respectively. Conclusion: We performed a 2-step study: a cadaveric study followed by an ultrasound on healthy volunteer which allowed us to define 3 standardized scan of the PTF joint. These sections allow a thorough study of the PTF joint and the surrounding structures although study of the posterolateral corner ligaments remains challenging. We think that this scanning method can be integrated into daily clinical practice in rheumatology and in sports medicine. Disclosure of Interests: None declared