1. Primer on
Partial Talotarsal Joint Dislocation

2. Dislocation –
“the displacement of any part, more especially
of a bone”
Dorlands Medical Dictionary

3. Types of dislocation:
closed, open, complete, incomplete,
traumatic, congenital, compound, simple,
complicated, fracture, habitual/recurrent,
partial, pathologic, subluxation, luxation.

4. Dislocation
• is a disease process
• is not normal
• needs to be treated/fixed
• failure to fix leads to other
pathologic conditions

5. Clinical Signs of Talotarsal Joint
Dislocation
Aligned TTJ
Balanced/Aligned hindfoot
Articular facets are in constant
congruent contact.
Minimal strain on the supporting
soft tissues- ligaments/tendons.
Mal-aligned TTJ
Imbalanced/Malaligned hindfoot
Articular facets are NOT
in constant congruent contact.
Excessive strain on the supporting
soft tissues- ligaments/tendons.

6. Radiographic Evidence of TaloTarsal
Joint Dislocation

7. Radiographic Evidence of TaloTarsal
Joint Dislocation
Normal TaloTarsal Joint TaloTarsal Joint Dislocation/Displacement
“Open” sinus tarsi Partial to full obliteration
of the sinus tarsi
Clinical significance: This immediately indicates that the talus is, at minimum, partially dislocated on
the tarsal mechanism. The joints/articular facets are no longer in constant congruent contact.

8. Radiographic Evidence of TaloTarsal
Joint Dislocation
Normal TaloTarsal Joint TaloTarsal Joint Dislocation/Displacement
Normal Talar Declination Angle
Normal = < 21 degrees
Abnormal Talar Declination Angle
Abnormal = > 21 degrees
Clinical significance: an increased talar declination angle indicates a sagittal plane deformity. Directly
responsible for increased strain on the medial column of the foot.

9. Radiographic Evidence of TaloTarsal
Joint Dislocation
Normal TaloTarsal Joint TaloTarsal Joint Dislocation/Displacement
Normal navicular height Navicular drop due to the dislocation
Clinical significance: navicular drop directly leads to excessive strain to the supporting structures of the
medial column of the foot such as the spring ligament, medial band of the plantar fascia and especially
the posterior tibial tendon and also disorders of the first ray/hallux.

10. Radiographic Evidence of TaloTarsal
Joint Dislocation
Normal TaloTarsal Joint TaloTarsal Joint Dislocation/Displacement
Normal cyma line Anterior plantar angulated cyma.
Clinical significance: the anterior displacement of the talus forces the navicular forward. This pushes
the medial cuneiform forward then the first metatarsal head into the base of the proximal phalanx
(hallux) leading to limited joint motion. This also unlocks the midtarsal joint leading to an excessively
long period of pronation.

11. Radiographic Evidence of TaloTarsal
Joint Dislocation
Normal TaloTarsal Joint TaloTarsal Joint Dislocation/Displacement
Notice that the calcaneal inclination angle (CIA) is the same.
Clinical significance: a lower than normal CIA indicates a “flat foot” (pes planovalgus). It is
possible to have a talotarsal dislocation without a “flat foot”.

12. Several Examples of Radiographic
Evidence of TaloTarsal Joint Dislocation

13. Normal Talar Second Metatarsal Angle
• Ideal 3-6 degrees
• Acceptable is < 16 degrees
• Indicator of transverse plane
talotarsal dislocation.

14. Talar Second Metatarsal Angle
• The bisection of the talus
compared to the forefoot
or the bisection of the 2nd
metatarsal.
• The outer/upper angular
range of normal is < 16
degrees.
• > 16 degrees is
considered pathologic
indicating a medially
displaced talus on the
tarsal mechanism.

15. Pathologic Talar Second Metatarsal Angle
Normal Abnormal

16. Partially Dislocated Talotarsal Joint
Posterior
Facets
Anterior/Middle
Facets.

17. • Talar Second Metatarsal
Angle (T2MA) > 16
• Significant transverse
plane deformity.
• This shows an
anteriomedial talotarsal
joint displacement.
Radiographic Evidence of TaloTarsal
Joint Dislocation

18. Radiographic Evidence of TaloTarsal
Joint Dislocation
Weightbearing image
with talotarsal joint in alignment/
neutral stance position
Weightbearing image
exhibiting talotarsal joint displacement/
relaxed stance position.
Clinical significance: The comparison of normal to abnormal flexible dislocation of the talus on the
tarsal mechanism. This is a recurrent dislocation.

19. • Relaxed stance
weightbearing
radiograph.
• T2MA > 16
• Talotarsal joint
displacement
Radiographic Evidence of TaloTarsal
Joint Dislocation

20. Radiographic Evidence of TaloTarsal
Joint Dislocation
• Relaxed stance weightbearing
radiograph.
• T2MA > 16
• Talotarsal joint displacement
• Note that there is minimal
anterior displacement.

21. Radiographic Evidence of TaloTarsal
Joint Dislocation
• Relaxed stance weightbearing
radiograph.
• T2MA > 16
• Talotarsal joint displacement
• Note anterior and medial
displacement.

22. Extra-osseous Talotarsal Stabilization
with internal fixation
Clinical significance: Talotarsal joint is realigned, articular facets remain in constant
congruent contact. Internal fixation device allows normal/natural talotarsal motion without
blocking/limiting motion. Restoration of the pathologic pre-existing deformities both
sagittal and frontal plane correction exhibited.

23. Extra-osseous Talotarsal Stabilization
with internal fixation.
Clinical significance: Talotarsal joint is realigned, articular facets remain in constant congruent contact.
Internal fixation device allows normal/natural talotarsal motion without blocking/limiting motion.
Restoration of the pathologic pre-existing deformity showing transverse plane correction with
normalization of the talar second metatarsal angle.

24. Thank you for your time.
We hope this has helped to shed
some light on this subject.