This document discusses radiological imaging of lateral hindfoot impingement. It provides illustrations and images showing normal hindfoot anatomy as well as examples of talocalcaneal impingement, subfibular impingement, and combined impingement. MRI and CT images demonstrate bone marrow edema, cystic changes, sclerosis, and soft tissue swelling associated with impingement between the talus, calcaneus, and fibula. Measurements of hindfoot valgus angle are also shown on imaging to evaluate impingement and alignment. Case studies with patients presenting lateral ankle pain further demonstrate imaging findings of extra-articular hindfoot impingement.

1. Radiological Imaging of lateral Hindfoot Impingement.
Dr/ ABD ALLAH NAZEER. MD.

2. Extra-articular lateral hindfoot impingement syndrome refers a non-
traumatic cause of ankle impingement. This can include talocalcaneal,
subfibular, and /or talocalcaneal-subfibular impingements.

5. Illustration shows lateral hindfoot impingement ( normal; talocalcaneal impingement with
hindfoot valgus and combined talocalcaneal and subfibular impingement with progressive
hindfoot valgus). α - Angle between the medial calcaneal cortex and the long axis of the tibia,
measured just posterior to the sustentaculum at the level of the posterior talus and tibia.

6. Weight bearing radiograph shows direct contact between the
talus and the calcaneus and sclerotic changes (arrows)

7. Weight bearing radiograph shows sclerotic changes between the talus
and the calcaneus at the point of the angle of Gissane (arrows).

8. Sagittal DP and DP FS show abnormal contact between calcaneus and talus with
opposing bone marrow edema in a case with lateral hindfoot impingement.

9. Sagittal fat saturated DP FS image shows marrow edema and cystic changes of opposing
lateral talar process and calcaneus (arrows) in a case with talocalcaneal impingement.

10. Coronal PD FS image shows lateral subluxation of calcaneus with increased angle between
the medial wall of the calcaneus and the long axis of the tibia. Care should be taken not to
use an image through the calcaneal sustentaculum tali as that would increase the angle.

11. Coronal proton density fat
saturated image (a) shows
edema and subchondral
cystic changes in the tip of
the fibula as well as soft-
tissue thickening between
the fibula and the
calcaneus. Sagittal fat
saturated PD images shows
marrow edema of opposing
lateral talar process and
calcaneus (b), as well as
better depicts the edema
and the cystic changes at
the tip of the fibula, in this
case of combined
talocalcaneal and subfibular
impingement (c). Note the
presence of a "neofacet"
between the lateral process
of the talus and calcaneus.

12. A,B; Sagittal fat saturated T2-wd images shows marrow edema of opposing lateral talar
process and calcaneus. C; Coronal proton density fat saturated image shows subchondral
cystic changes in posterior subtalar facet in a case with talocalcaneal impingement.

13. Coronal CT image shows calcaneal facet articulating with distal fibula (red
arrow). Lateral subluxation of calcaneus and subchondral changes in posterior
subtalar facet (yellow arrow) are compatible with combined talocalcaneal and
subfibular impingement on the left side in a case with old calcaneal fracture.

14. A; Sagittal T2-wd fat saturated image shows abnormal contact between calcaneus and
talus with opposing bone marrow edema and cystic changes in a case with lateral hindfoot
impingement. B; coronal fat saturated PD image shows thickened calcaneofibular
ligament, due to entrapment between the fibula and the calcaneus (PTF: posterior
talofibular ligament, PT: peroneal tendons, red arrow; thickened calcaneofibular ligament).

15. Due to hindfoot valgus, soft tissue edema and impingement is seen between the
fibula and the calcaneus (yellow arrows) without prominent bony changes (red
arrow; peroneal tendons). B; Malalignment results dislocation of peroneal tendons
(arrow). Peroneal tendon dislocation is not related to lateral ankle impingement.

16. Sagittal T1- and
fat-suppressed
T2-weighted
(1a,1b), and
coronal fat-
suppressed
proton density-
weighted
(1c,1d) images.
Lateral hindfoot
impingement,
with extra-
articular
talocalcaneal
impingement
and subfibular
(calcaneofibular
) impingement.

17. Lateral hindfoot
impingement, with
extra-articular
talocalcaneal
impingement and
subfibular
(calcaneofibular)
impingement.

18. Lateral hindfoot impingement involves
the anatomic structures at the junction
of the posterior subtalar joint and the
posterolateral margin of the sinus
tarsi, including the lateral malleolus.

19. T1 Sagittal – Advanced Sub-talar Osteoarthritis. Blue arrow indicates loss of normal
fat signal in sinus tarsi reflective of a sinus tarsitis. There is also subcortical sclerosis.
The distance between the lateral talar process and the calcaneus at the apex of the
angle of Gissane decreases with progressive impingement and osteoarthritis.

20. Extra-articular lateral hindfoot impingement in a 13-year-old boy with 4 years of lateral ankle pain with
no known injury. a Sagittal T1-W MR image shows an accessory anterolateral talar facet (asterisk) that
protrudes anterior to a vertical line bisecting the critical angle of Gissane. Fibrotic scar tissue is associated
with the roots of the extensor retinaculum in the sinus tarsi. b Sagittal short tau inversion recovery (STIR)
MR image shows the cervical ligament entrapped between the accessory facet and anterior calcaneus
(arrow) and mild edema-like signal in the sinus tarsi. c Coronal proton-density MR image shows normal
calcaneofibular ligament (arrow) with obliquity of the calcaneus in keeping with hindfoot valgus

21. Extraarticular lateral hindfoot impingement in a 17-
year-old boy with intermittent ankle pain for many
months but no known injury. a No accessory
anterolateral talar facet is present on this sagittal T1-
W MR image. The solid lines reflect the critical angle
of Gissane and the dashed line bisects the angle. Bone
does not protrude anterior to the dashed line
indicating absence of an accessory anterolateral talar
facet. b MRI measurement of hindfoot valgus on a
coronal proton-density MR image. Note incidental
lobular hypointense structure in the calcaneus, which
is hyperintense and might represent vascular
remnants or an intraosseous ganglion. c Coronal
proton-density MR sequence shows entrapped
calcaneofibular ligament, which is markedly thickened
with intermediate intrasubstance signal
(arrow). d Sagittal T1-W MR image shows
replacement of normal hyperintense fat by
hypointense signal tissue, which surrounds the
calcaneofibular ligament (CFL) between the fibula and
calcaneus, consistent with subfibular
impingement. e Sagittal short tau inversion recovery
(STIR) MR image corresponding to (d) shows the
thickened CFL to better advantage. f, g Sagittal T1-W
(f) and STIR (g) MR images show effacement of fat on
T1 and hyperintense signal on the fluid-sensitive
sequence within the sinus tarsi and within the talus at
the roof of the sinus tarsi, which is associated with
extraarticular lateral hindfoot impingement.

22. 60-year-old man with lateral
ankle pain. A and B, Sagittal T1-
weighted fast spin-echo (A) and
sagittal inversion recovery (B)
images show cystic changes and
marrow edema at lateral talar
process (solid arrows) and
opposing lateral calcaneus (open
arrows). C, Coronal T2-weighted
fast spin-echo fat-saturated
image shows moderate hindfoot
valgus angle of 22°. Lateral
calcaneal marrow edema (star)
and subcutaneous edema
(arrow) are noted. D, Axial T2-
weighted fast spin-echo fat-
saturated image shows type Ia
posterior tibial tendon tear with
mild morphologic irregularity
and increased tendon size
(arrow)

23. 65-year-old woman with clinical history of posterior tibial tendon dysfunction. A and B, Sagittal T1-
weighted fast spin-echo (A) and sagittal inversion recovery weighted (B) sequences show signal
alterations at opposing osseous contact surfaces of talus and calcaneus, representing sclerosis (solid
arrows) and marrow edema (open arrows, B). C and D, Sagittal T1-weighted fast spin-echo (C) and
sagittal inversion recovery weighted (D) images show subfibular soft-tissue abnormality depicted by
hypointense T1 and both hyper- and hypointense T2- weighted signal (arrowheads).

24. 83-year-old woman with history of posterior
tibial tendon dysfunction and lateral ankle
pain, depicted by marker, showing combined
talocalcaneal–subfibular impingement. A,
Coronal T1-weighted fast spin-echo image
shows cystic changes and sclerosis at
opposing talus and calcaneus (white
arrows). Intermediate-signal soft tissue is
entrapped between fibula and calcaneus
(black arrow). B, More posterior coronal T1-
weighted fast spin echo image illustrates
direct osseous contact between fibula and
calcaneus (arrow) with calcaneal “neofacet”
(star). Hindfoot valgus angle, formed by
intersection of line along medial calcaneal
wall and line parallel to long axis of tibia, is
increased (32°). C, Coronal T2-weighted fat-
suppressed image depicts fibular marrow
edema (star). D, Axial proton density–
weighted fast spin-echo image illustrates
peroneal tendon subluxation (black arrow)
and grade III posterior tibial tendon tear
(arrowhead). Direct contact between fibula
and calcaneus (white arrows) is also
identified.

25. Thank You.