From the Guidelines
The Kager fat pad is located in the posterior aspect of the elbow, associated with the posterior fat pad sign, which is relevant in the context of supracondylar fractures of the humerus in children. This anatomical structure is significant in orthopedic assessments, particularly in the evaluation of elbow injuries. The posterior fat pad sign is a radiological finding that can indicate the presence of a fracture or other elbow pathologies 1. In clinical practice, understanding the location and significance of the Kager fat pad is crucial for accurate diagnosis and management of elbow conditions, including supracondylar fractures of the humerus in pediatric patients. Key points to consider include:
- The Kager fat pad is associated with the posterior aspect of the elbow
- It is relevant in the diagnosis of supracondylar fractures of the humerus in children, as indicated by the posterior fat pad sign 1
- Accurate identification and interpretation of this sign are critical for appropriate management and treatment of elbow injuries.
From the Research
Location of Kager's Fat Pad
- Kager's fat pad is located in Kager's triangle between the Achilles tendon, the superior cortex of the calcaneus, and flexor hallucis longus (FHL) muscle and tendon 2.
- It is a mass of adipose tissue occupying Kager's triangle, with three regions closely related to the sides of the triangle: parts related to the Achilles and flexor hallucis longus (FHL) tendons and a wedge of fat adjacent to the calcaneus 3.
- The fat pad is consistently adherent to the Achilles at its posterior aspect, with the most distal part detaching from the Achilles to give way to the retroalcaneal bursa 4.
Anatomy and Function
- Kager's fat pad has specialized functions, including an FHL part that contributes to moving the bursal wedge during plantarflexion, an Achilles part that protects blood vessels entering the tendon, and a bursal wedge that minimizes pressure changes in the bursa 3.
- The protruding wedge of the fat pad assists in the lubrication of the Achilles tendon subtendinous area, distributes stress at the Achilles enthesis, and removes debris from within the retrocalcaneal bursa 2.
- The fat pad undergoes significant deformation during plantar flexion, with the wedge being forced into the retrocalcaneal bursal space, and its pressure changes during ankle range of motion 4.
Clinical Significance
- Kager's fat pad scarring with Achilles tendon tethering may mimic or exacerbate Achilles tendinosis symptomatology and should be considered a possible diagnosis when conservative treatments for Achilles tendinosis fail 5.
- Pathological changes to the fat pad may be clinically important in the development of Achilles tendinopathy 4.
- Low-volume hydrodissection, a procedure that mechanically separates the paratenon from the underlying Kager's fat pad, may be an effective treatment option for chronic Achilles tendinopathy 6.