Голеностопный сустав
Нормальная рентгеноанатомия, укладки
The ankle consists of a fork formed by the tibia, the fibula and the talus. Together they form the superior tarsal joint. The primary movement taking place here is dorsiflexion (“toes towards you”) and plantar flexion (“toes away from you”).
The primary movement of the subtalar joint is inversion and eversion.
The ankle x-ray is used primarily to demonstrate/exclude a fracture.
The primary movement of the subtalar joint is inversion and eversion.
The ankle x-ray is used primarily to demonstrate/exclude a fracture.
Figure 2. Technique and example of an AP image.
Depending on the request, various images can be made. A standard series includes an anteroposterior (AP) image, a Mortise image and a lateral image.
When calcaneal pathology is suspected, an additional image can be made in axial direction.
Pure AP image (fig. 2).
When calcaneal pathology is suspected, an additional image can be made in axial direction.
Pure AP image (fig. 2).
Figure 3. Technique and example of a Mortise image.
Mortise image
This is an AP image where the ankle is turned 15°- 20° inward (= endorotation). This will prevent the fibula from overlapping the talus. This image allows for better free projection of the superior tarsal joint as compared to a pure AP image (fig. 3).
This is an AP image where the ankle is turned 15°- 20° inward (= endorotation). This will prevent the fibula from overlapping the talus. This image allows for better free projection of the superior tarsal joint as compared to a pure AP image (fig. 3).
Figure 4. Technique and image of a lateral ankle.
Lateral image
Includes the full calcaneus. Ideally, the base of metatarsal I is also imaged (fig. 4).
Includes the full calcaneus. Ideally, the base of metatarsal I is also imaged (fig. 4).
Figure 5. Technique and image of an axial calcaneus in standing position.
Axial calcaneal image
The x-ray can be made in both standing and supine position, the foot is in dorsiflexion (fig. 5).
The x-ray beam passes the calcaneus.
The x-ray can be made in both standing and supine position, the foot is in dorsiflexion (fig. 5).
The x-ray beam passes the calcaneus.
Figure 6. Pure AP image of a normal left ankle. MM = medial malleolus, LM = lateral malleolus.
Normal anatomy
The ankle consists of a fork formed by the tibia, the fibula and the talus. Together they form the superior tarsal joint (fig. 6). The primary movement taking place here is dorsiflexion (“toes towards you”) and plantar flexion (“toes away from you”).
The medial and lateral sides of the superior tarsal joint are formed by the talus/medial malleolus and the talus/lateral malleolus respectively.
The ankle consists of a fork formed by the tibia, the fibula and the talus. Together they form the superior tarsal joint (fig. 6). The primary movement taking place here is dorsiflexion (“toes towards you”) and plantar flexion (“toes away from you”).
The medial and lateral sides of the superior tarsal joint are formed by the talus/medial malleolus and the talus/lateral malleolus respectively.
Figure 7. Mortise image of a normal left ankle. MM = medial malleolus, LM = lateral malleolus.
As indicated previously, a Mortise image (= AP image in 15°- 20° endorotation) is made in particular to project the superior tarsal joint free of superimposition. Ankle endorotation reduces overlap of the lateral malleolus and the talus, bringing the lateral side of the superior tarsal joint better in view (fig. 7).
Figure 8. Ligaments of the lateral malleolus (a/b), including the syndesmosis (= yellow ligaments).
The syndesmosis is a key stabilizer of the ankle and consists of (fig. 8):
In a normal ankle, the joint space of the superior tarsal joint should be the same everywhere, a so-called congruent/symmetrical ankle fork.
- the anterior tibiofibular ligament.
- the posterior tibiofibular ligament.
- the interosseous ligament.
In a normal ankle, the joint space of the superior tarsal joint should be the same everywhere, a so-called congruent/symmetrical ankle fork.
Figure 9. The various clear spaces in the ankle.
The distance between the distal tibia and fibula is important, also known as the tibiofibular clear space (fig. 9).
It is measured at 10 mm cranial from the tibial plafond. When the distance between the distal tibia and fibula > 6 mm, be alert for a tear or rupture of the interosseous ligament.
Suspect medial ligament damage if the medial clear space is larger than the superior clear space. Important: damage to the medial collateral ligaments is frequently associated with syndesmosis damage.
It is measured at 10 mm cranial from the tibial plafond. When the distance between the distal tibia and fibula > 6 mm, be alert for a tear or rupture of the interosseous ligament.
Suspect medial ligament damage if the medial clear space is larger than the superior clear space. Important: damage to the medial collateral ligaments is frequently associated with syndesmosis damage.
Figure 10. Normal anatomy in lateral image of a left ankle. MT5 = metatarsal 5, mal. tertius = malleolus tertius (= posterior malleolus).
Lateral ankle image
The malleoli are superimposed on the lateral image. The lateral malleolus (= fibula) continues on downward.
The posterior malleolus is the posterior side of the distal tibia, also known as the malleolus tertius (fig. 10).
The malleoli are superimposed on the lateral image. The lateral malleolus (= fibula) continues on downward.
The posterior malleolus is the posterior side of the distal tibia, also known as the malleolus tertius (fig. 10).
Figure 11. Normal anatomy in a lateral image of the calcaneus (a) and the outlines of the trabeculae (b).
The calcaneus comprises four joint surfaces: one with the cuboid and 3 articulations (anterior, medial and posterior) with the talus (fig. 11).
The trabeculae protect the calcaneus against axial and shear forces (fig. 11b). The neutral zone contains the fewest trabeculae and is therefore the most vulnerable part of the calcaneus.
The trabeculae protect the calcaneus against axial and shear forces (fig. 11b). The neutral zone contains the fewest trabeculae and is therefore the most vulnerable part of the calcaneus.
Figure 12. Normal anatomy in axial image of the calcaneus.
Axial calcaneal image
In particular, the posterior 2/3rd segment of the calcaneus can be seen clearly (fig. 12).
The sustentaculum tali is a bony outcropping on the medial side of the calcaneus and supports articulation of the medial talus facet. Under the sustentaculum tali is the flexor hallucis longus tendon (= flexor tendon dig I).
In particular, the posterior 2/3rd segment of the calcaneus can be seen clearly (fig. 12).
The sustentaculum tali is a bony outcropping on the medial side of the calcaneus and supports articulation of the medial talus facet. Under the sustentaculum tali is the flexor hallucis longus tendon (= flexor tendon dig I).
Figure 13. Common accessory ossicles of the ankle.
Accessory ossicles
The ankle/foot contains many different accessory ossicles.
These small ossal structures may be mistaken for an (avulsion) fracture. An accessory ossification center is smooth and rounded, as opposed to a fracture where the fragment is vague and irregular.
The ankle/foot contains many different accessory ossicles.
These small ossal structures may be mistaken for an (avulsion) fracture. An accessory ossification center is smooth and rounded, as opposed to a fracture where the fragment is vague and irregular.
Figure 14. Accessory os subfibulare. MM = medial malleolus, LM = lateral malleolus.
In addition, the exact pain location must be ascertained; accessory ossicles generally do not induce pain symptoms.
Below is an outline of a number of common accessory ossicles of the ankle (fig. 13). Figure 14 shows an example of an accessory ossicle.
Below is an outline of a number of common accessory ossicles of the ankle (fig. 13). Figure 14 shows an example of an accessory ossicle.
Checklist
The following points may be used as a guide to assess an ankle x-ray (some terms are explained in more detail in the Pathology section).
General:
Specific to a distal fibular fracture:
The following points may be used as a guide to assess an ankle x-ray (some terms are explained in more detail in the Pathology section).
General:
- Technique: has everything been imaged correctly; is it suitable for evaluation?
- Soft tissues: swelling? skin intact? Other: includes foreign body or atherosclerosis?
- Bone mineral density?
- Position of ankle fork? Cortical interruptions?
- Joint articulation: osteoarthritis? luxation?
- If a calcaneal fracture is suspected: interruptions of the trabeculae? Böhler's angle?
- Accessory ossicles? Normal epiphyseal plates?
- Abnormalities outside the ankle joint?
Specific to a distal fibular fracture:
- Determine the level versus the syndesmosis.
- Is there a fracture of the medial malleolus and/or posterior malleolus (= tertiary)?
- Abnormal clear spaces?
Sources
- B.J. Manaster et al. The Requisites – Musculoskeletal Imaging (2007).
- N. Raby et al. Accident & Emergency Radiology – A Survival Guide. (2005).
- K.L. Bontrager, J.P. Lampignano. Textbook of Radiographic Positioning and Related Anatomy. 2014 (8th edition)
- http://www.startradiology.com/