9 - Arthrography and Tenography Flashcards
Arthrography
Uses contrast injected into a joint to demonstrate abnormalities not evident on radiographs
First you inject it into the joint, then you take an x-ray
Contrast types
Positive contrast
- Iodinated radiopaque material
- The concern with this is an iodine allergy (ask about shellfish allergy***)
- If they are allergic to shellfish/iodine, you can do a negative contrast
Negative contrast
- Inject air into the joint instead
- It isn’t going to kill them (contrary to popular belief)
THIS IS IMPORTANT
Know the reason why you use one or the other (shellfish allergy)
Most common joint for arthrography
Ankle
Indications for ankle arthrography
- Soft tissue trauma (ligamentous tear, injury to joint capsule)
- Osteochondaral defects
- Loose bodies
Technique for ankle arthrography
- Inject lidocaine over site
- Sterile betadine prep and sterile technique
- Enter ankle with a 23 gauge needle just medial to the tibialis anterior tendon
- Inject 8-10 cc of contrast material
- Passive ROM of ankle
- Examine under fluroscopy
Don’t want them to get a septic joint or an infected joint, so you need to use sterile betadine prep to avoid introducing bacteria
The easiest place to enter the ankle joint is just medial to the tibialis anterior tendon
You inject until you feel back pressure… Bigger people will take more contrast, smaller people will take less contrast (based on size) - this is the “maximum content” of the joint = “INSUFLATE” the joint = buzz word ***
After injecting contrast, do some passive ROM of the ankle to distribute the contrast before doing to fluroscopy or x-ray
Study on quantifying normal ankle joint volume on cadavers
- Level 5 cadaveric study
- Examined 9 cadavers and injected 2 mL of contrast in ankle
- Mean maximum joint volume was 20.9 mL with a range of 16-19 mL
- Don’t want to put too much in though (stick to 8-10 mL) because you can burst the joint capsule
Normal arthrography findings
- Anterior and posterior recesses of the joint fill with contrast and will be smooth
- Contrast can extend 1 cm above joint surface and distally to talar head and neck
- Contrast may extend between tibia and fibula 2.5 cm above ankle
- Communication to posterior STJ: 10%
- Contrast along needle tract
You are looking for SMOOTH delineation
When there is a rupture in the capsule and there is leak out, you will see the contrast running everywhere
Abnormal arthrography findings
- Extravasation of contrast beyond the confines of the joint
- CFL tear with contrast in the peroneal tendon sheath
What is the “buzz word” when looking at an abnormal arthrography?
EXTRAVASAION
- Contrast found outside of the joint capsule
CFL tear
- Can see contrast in the peroneal tendon sheath
- You shouldn’t be able to inject contrast in the joint on the medial ankle and have it flow up the tendon sheath on the lateral side of the ankle
ABNORMAL = contrast found in the peroneal tendon sheath (slide 15)
Most common joint for arthrography and other joints that can be used
Ankle is the MOST common
- Very easy and convenient due to size
Second most common is the second MPJ or even the first MPJ
Other joints are harder to enter and do NOT have a well defined capsule
How common with arthrography be used?
15 or 20 of us will be questioned about arthrography on board exams or during residency
Only 2 of us will actually do this
Tenography
Uses contrast injected into tendon sheaths to diagnose inflammatory or posttraumatic conditions
Does every tendon have a tendon sheath?
Every tendon does NOT have a tendon sheath
If a tendon changes direction or angle, it DOES have a sheath
If a tendon has a straight trajectory, it does NOT have a tendon sheath (Achilles)
What is harder to do, a tenogram or a arthrogram?
Tenogram
