The poster is structured into intuitive, visually guided sections to facilitate easy navigation and rapid learning:  

Anatomy and Functional Overview

[fig]1 Describes anatomical overview of the anterior knee structures and the various layers of anterior knee. A figure depicting the three knee fat pads in lateral radiograph, CT and MRI is also depicted with brief mention of other adjacent fat pads.

[fig]2 shows detailed anatomical description of Hoffa’s fat pad, including boundaries, vascular supply, innervation, fibrous condensation and synovial clefts.

Knee fat pads act as dynamic, deformable shock absorbers that adapt to joint contours to maintain homeostasis. They cushion the patellar tendon, distribute synovial fluid, and stabilize patellar tracking during movement. Rich innervation suggests a proprioceptive role in sensing joint pressure. Pathological stiffening from fibrosis or inflammation disrupts these mechanics, resulting in impingement and pain.

MRI Signal Correlation Key

A simplified visually appealing key is used to differentiates normal from pathological signals across T1, T2, PDFS and gradient sequences. [fig]3 summarizes these characteristics in normal knee MRI and pathological conditions to aid in rapid identification of pathology. The same key is used in all the slides to depict that particular pathology. This section will act as a rapid reference tool.

Examples include:

• T1 hypointense + PD FS hyperintense → inflammatory edema / impingement
• Blooming on GRE → hemosiderin/calcification-related pathology (e.g. PVNS)
• Fat-signal lesion with septations → lipoma / lipoma arborescens
• Low signal bands and volume loss → fibrosis / postoperative scarring

Optimized Classification System [fig]4

An optimized, imaging-oriented classification system is proposed in order to group lesions based on their etiology and imaging behavior rather than isolated histopathological entities. This will allow radiologists to trace pathology from imaging to diagnosis via clinical correlation along with the radiological findings.  

Broad categories include: Primary Intrinsic Fat Pad Pathology and Extrinsic Pathology including Articular, Synovial and Extracapsular disorders. 

To facilitate navigation, each pathological entity features a classification header that specifies its diagnostic category at a glance.

Fat Pad Pathologies

Each figure is comprehensive and is designated to include:

• Clinical vignette
• Key imaging findings across: X-ray, CT, USG (if needed), MRI and key morphological appearance (Diagnostic pearl)—a concise takeaway point that aids in reporting accuracy and differentiating often misdiagnosed pathology.
• A classification header that specifies its diagnostic category at a glance.
• The pathological images have been annotated to point the pathology and is described in the caption associated with the figure.

Intrinsic pathologies have been described first followed by extrinsic pathologies.

INTRINSIC

[fig]5 is a comprehensive glance at Hoffa’s disease. Pathogenesis and clinical features have been described and a table is provided listing the most common morphologic parameters leading to SHFP edema. [fig]6 and [fig]7 show acute and chronic impingement.

[fig]8 and [fig]9 show two cases of focal form of pigmented villonodular synovitis/ focal nodular synovitis. Diffuse form of PVNS is described in [fig]17. 

[fig]10 and [fig]11 describe fibrosis and trauma respectively.

EXTRINSIC

The extrinsic pathologies have been divided based on their origin from articular, synovial or extracapsular structures. The synovial pathologies have been further classified based on internal hemosiderin deposition, calcification, fatty proliferation and inflammatory/infectious etiology.

The predominant cystic pathologies involving the fat pads are shown in [fig]12 – Meniscal cyst, [fig]13 – Ganglion cyst and [fig]14 – Diffuse ganglionosis that is also involving the Hoffa’s fat pad.

[fig]15 – Cyclops lesion, commonly seen in cases post ACL reconstruction.

Loose bodies in the knee joint space can have varied origin and such a case is described in [fig]16.

[fig]18 and [fig] 19 depict two cases of synovial hemangioma.

[fig]20 illustrates the classic imaging features of Synovial Chondromatosis, characterized by multiple intra-articular osteochondral bodies. A comparative analysis is provided in [fig]21, differentiating this primary synovial pathology from its key mimics: para-articular chondroma (articular involvement) and synovial chondrosarcoma (malignant transformation).

[fig]22 depicts lipoma arboroscens,  a finding seen mostly secondary to a preexisting condition in the knee.

Various non-specific proliferative and inflammatory pathologies that are described include:

• Maduramycosis [fig]24
• Rheumatoid Arthritis [fig]25
• Juvenile Inflammatory Arthritis [fig]26
• Osteomyelitis [fig]27

A summary of these pathologies is included in [fig]23

[fig]28 delineates the imaging spectrum of Osgood-Schlatter disease, with a detailed focus on its pathogenesis as a traction apophysitis of the tibial tubercle. The illustration correlates repetitive microtrauma with the resulting characteristic fragmentation and soft-tissue edema.

Diagnostic Workflow A key highlight of this poster is the step-by-step diagnostic workflow [fig]29 designed for quick application in routine knee MRI reporting. The following parameters have been taken into consideration –

• Origin of Lesion: Classification as either Intrinsic or Extrinsic.
• MRI Signal Characteristics: Assessment of T2 signal intensity (High vs. Low) and GRE blooming (presence of hemosiderin).
• Clinical and Surgical History: Presence of repetitive trauma, prior surgery (e.g., arthroscopy or ACL reconstruction), or known bleeding disorders.
• Nature of the Process: Differentiation between Cystic/Fluid collections and Synovial Proliferation.
• Anatomical Site/Morphology: Identification of specific patterns such as linear sites, extensive involvement, fat-signal fronds, or multiple osteochondral bodies.
• Associated Pathology: Presence of secondary findings like a meniscal tear, joint effusion, or phleboliths.

The provided table [fig]30 serves as a diagnostic reference to categorize various knee fat pad pathologies into specific clinical groups such as edematous, post-traumatic, cystic, synovial, neoplastic, and infective conditions. It facilitates rapid identification by mapping these categories to their characteristic MRI features, key differentiators, and recommended clinical next steps.