Scapholunate Advanced Collapse (SLAC-wrist)

Figure: Frontal radiograph of the wrist shows marked degenerative change (joint space narrowing and subchondral sclerosis) of the radioscaphoid joint (yellow arrowheads), widening of the scapholunate space, and proximal migration of the capitate (C) filling in this widened space. The radiolunate joint (red arrowheads) is spared by degeneration.

Scapholunate Degeneration

• Insufficiency of scapholunate and radioscapholunate ligaments, causing increased mobility of the scaphoid on the radius
• Abnormal load to the capitate upon lunate, then capitate enters the widened scapholunate joint space and approximates distal radius
• Three stages: the third stage is called "SLAC wrist", in which the capitates enters the scapholunate gap and approaches the distal radius. The radiocarpal joint at lunate is spared by degeneration.

Etiology

CPPD deposition disease, rheumatoid arthritis, trauma, neuropathy, amyloid deposition

Reference:

1. Stabler A, Heuck A, Reiser M. Imaging of the hand: degeneration, impingement and overuse. Eur J Radiol 1997;25:118-128.

Submandibular Sialadenitis with Abscess

Coronal and sagittal CT images show an enlarged left submandibular gland with two well-defined rim enhancing fluid collections in the anterior aspect of the gland, representing abscesses. There is adjacent subcutaneous fat stranding.

Sialadenitis

• Most common salivary gland abnormality is infection, either bacterial or viral
• Bacterial infection ascends from oral cavity. Most common pathogens are S. aureus, S. viridans, H. influenza
• Most common viral infection is mump
• Most common site = parotid > submandibular gland
• Predisposing factors are dehydration, radiation, immunosuppression
• Other causes of sialadenitis include inflammation (sialolithiasis, radiation), autoimmune (Sjogren, lupus), granulomatous (TB), drug, etc.

Sialadenitis vs Abscess

• Sialadenitis is treated with antibiotics, while abscess usually needs surgery
• Abscess may spread to deep neck spaces and progress to Ludwig angina
• CT can differentiate the two entities. Abscess is seen as localized low attenuation, walled-off region in contrast to dense, enhanced gland
• CT can show calcified sialolithiasis, and in some cases noncalcified sialolithiasis as a cause of duct obstruction

References:

1. Yoskovitch A. Submandibular sialadenitis/sialadenosis. emedicine Jul 23, 2008.

2. Silvers AR, Som PM. Salivary glands. Radiol Clin North Am 1998;36:941-966.

Ankle Mortise Radiographic View

Figure 1: "Inadequate mortise view of the right ankle" in a patient with lateral malleolar fracture and torn deltoid ligament. Note that the radiograph was taken without adequate internal rotation of the ankle joint. The entire tibiotalar joint space is not clearly shown, particularly the lateral clear space. On this image, the medial clear space (arrowheads) appears normal.

Figure 2: "Adequate" mortise view of the same patient shows disruption of the deltoid ligament, which is shown as widening of the medial clear space (arrowheads).

Ankle Mortise View

• Anteroposterior view with ankle internally rotated 15 to 20 degrees
• Considered adequate if - tibiotalar joint well demonstrated entirely and medial/lateral clear spaces are open
• Used to assess - tibiotalar articular surface, integrity of ankle mortise, and medial/lateral clear spaces

Normal

• Entire tibiotalar joint space is uniform in width
• Normal overlap between distal tibia and fibula about 1 mm, or a little wider than tibiotalar joint space

Our case emphasizes the importance of determining the adequacy of radiographic techniques before interpreting radiographs as normal. In our case, findings are consistent with a supination-external rotation (SER) type of ankle fracture.

Reference:

Schwartz DT, Reisdorff EJ. Emergency Radiology. McGraw-Hill Professional, 1999.

Capitellar Osteochondritis

A 10 yr old gymnast presented with right elbow pain

Timing of ossification center at elbow

CRITOE
Capitellum appears by 8 months

Radial head 3-4 yrs

Internal (medial) epicondyle 5 yrs

Trochlea 7 yrs

Olecranon 9 yrs

External (lateral) epicondyle 11 yrs

Capitellar osteochondritis

• Results from overuse of elbow causing subchondral reactive process and loosening of cartilage and bone
• Usually occurs at anterior surface of capitellum
• Imaging findings show flattening of capitellar surface, or visible lucent zone of defect and sometimes can demonstrate intrarticular fragment of loose bodies.
• Unstable lesions include large size (typically > 1 cm), cystic lesion beneath the osteochondrotic site, containing loose granulation tissue or loose fragement, fluid insinuating beneath the fragment

Reference Elbow In: Stoller DW, Tirman PFJ, Bredella MA . in Diagnostic Imaging: Orthopaedics. Amirsys.2003.

Inferior Vena Cava (IVC) Filter Fracture

Figure 1: Abdominal radiograph shows that one of the legs (arrows) of the IVC filter is pointed away from the expected IVC lumen.

Figure 2: Axial CT image confirms that one of the legs (arrow) of the IVC filter has migrated out of the IVC wall into an adjacent tissue.

Fracture of IVC Filter Element

If the fragment migrates to adjacent tissues

- Asymptomatic patient: no treatment necessary

- Symptomatic patient: confirm location with CT scan and consider surgical removal if feasible

If fracture results in compromise of filter function: place a second filter

Reference:

Kaufman JA. Vena Caval Filters. In: Kandarpa K and Aruny JE, eds. Handbook of interventional radiologic procedures. 3rd ed. 2002