Denis classification of sacral fractures

⚪️ There are several classification systems for sacral fractures, but the most commonly employed are the Denis classification and subclassification systems, and the Isler classification system.

⚪️ Denis classification: 

• zone 1: fracture involves the sacral ala lateral to the neural foramina

• zone 2: fracture involves the neural foramina, but does not involve the spinal canal.

• zone 3: fracture is medial to the neural foramen, involving the spinal canal; these may be transverse or longitudinal, and can be sub-classified into 4 types:

• type 1: only kyphotic angulation at the fracture site (no translation).

• type 2: kyphotic angulation with anterior translation of the distal sacrum.

• type 3: kyphotic angulation with complete offset of the fracture fragments.

• type 4: comminuted S1 segment, usually due to axial compression.

⚪️ Morphologic injury patterns of zone 3 fractures:

🔶️ “H” shaped fracture

🔶️ “U” shaped fracture

🔶️ “ʎ” (lambda) shaped fracture

🔶️ “T” shaped fracture

Ureterocele

⚪️ Contrast enhanced pelvic CT showing a well-defined intravesical cystic outpouching at the left ureteric orifice with the characteristic cobra-head appearance.

⚪️ These findings are consistent with left ureterocele.

Ulnar variance radiology

⚪️ Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna and is primarily a plain radiographic determination. 

⚪️ Ulnar variance may be:

🔲 Neutral (both the ulnar and radial articular surfaces at the same level)

➕️ Positive (ulna projects more distally)

➖️ Negative (ulna projects more proximally)

⚪️ Variance is independent of the length of the ulnar styloid process.

Toxic megacolon

Brief video : Toxic megacolon

Toxic megacolon radiology:

Toxic megacolon is a life-threatening widening of the colon paired with severe systemic illness. 

Radiology shows segmental or total colonic distension—typically greater than 6 cm at the transverse colon—along with loss of haustral folds, mucosal islands, and a thin, damaged bowel wall. 

🚫 Barium enemas and colonoscopy 🚫 are strictly avoided due to perforation risks.

🩻 Key Radiographic Findings 🩻:

Abdominal X-ray:

🔶️ Marked colonic dilation (>6 cm, especially in the transverse colon).

🔶️ Loss of normal haustral markings (ahustral pattern).

🔶️ Mucosal "thumbprinting" or pseudopolyps from severe wall edema and ulceration.

🔶️ Free air under the diaphragm if bowel perforation occurs.

CT Scan:

🔷️ Confirms total or segmental colonic distension.

🔷️ Shows marked pericolic fat stranding and wall abnormalities.

🔷️ Identifies free fluid (ascites) or early micro-perforations.

Haller’s Index in Pectus Excavatum 🫁

The Haller Index is a key measurement used on chest CT to assess the severity of pectus excavatum.

📏 Formula:

Haller Index = Transverse Diameter ÷ AP Distance

• Transverse diameter → widest internal chest width

• AP distance → shortest distance between sternum and vertebra

📊 Interpretation:

✔ Normal: < 2.0

⚠ Mild–Moderate: 2.0 – 3.2

❗ Severe: > 3.5

🔎 Surgical consideration:

👉 Haller Index ≥ 3.25

Clean measurement. Clear decision-making. Better outcomes.

Fabella and cyamella

● The fabella is a small sesamoid bone found embedded in the tendon of the lateral head of the gastrocnemius muscle behind the lateral condyle of the femur. 

● The fabella can also be fibrocartilaginous in nature and is occasionally found in the medial head of the gastrocnemius. The fabella articulates with its respective (medial or lateral) femoral condyle.

● It is an accessory bone, an anatomical variation present in 39% of humans.

● Rarely, there are two or three of these bones (fabella bi- or tripartita). 

● It can be mistaken for a loose body or osteophyte. 

● The word fabella is a Latin diminutive of faba 'bean'.

● It is more common in men than women, older individuals compared to younger, and there is high regional variation, with fabellae being most common in people living in Asia and Oceania and least common in people living in North America and Africa.

● Bilateral cases (one per knee) are more common than unilateral ones (one per individual), and within individual cases, fabellae are equally likely to be present in right or left knees. 

● The fabella can lead to posterolateral knee pain either due to cartilage softening (chondromalacia fabellae) or other osteoarthritic changes on its articular surface.

● The most relevant differential diagnosis is the cyamella which is a rare sesamoid bone that exists as a normal variant within the popliteus tendon, characteristically located at the posterolateral aspect of the distal femur in the popliteal groove.

■ A cyamella (sometimes called popliteal fabella, fabella distalis, sesamoideum genu inferius laterale).

■ Cyamella is best seen on the AP view of plain radiograph as opposed to the fabella, which is located in the lateral head of the gastrocnemius and best appreciated on the lateral view.

■ It is round/ovoid, sometimes flattened and generally smaller than fabella.

■ Three locations have been described :

▪︎ Lateral to lateral femoral condyle, near popliteal sulcus (origin of popliteus tendon).

▪︎ Lateral to tibial condyle, near tibial plateau and fibular head (close to popliteofibular ligament).

▪︎ Between tibia and fibular head, posteromedial to tibiofibular joint (distal popliteus).