Retrocalcaneal Pain

Radiographic findings may include:

  • spur
  • erosion
  • ossicle
  • increased soft tissue density
  • ill-defined increased bone density
  • increased Fowler-Philip angle
  • positive parallel pitch line

Differential Diagnosis:

  • Retrocalcaneal bursitis
  • Inflammatory arthritis
  • Fracture of talus posterolateral process vs. symptomatic os trigonum
  • Haglund’s deformity
  • Calcaneal stress fracture

Here are examples of retrocalcaneal pathology with interpretations (*):

  • Case 1a
  • *Case 1a
  • *Case 1b
  • Case 2a
  • *Case 2a
  • *Case 2b
  • Case 3
  • *Case 3
  • Case 4a
  • *Case 4a
  • Case 4b
  • *Case 4b
  • Case 5a
  • *Case 5a
  • Case 5b
  • *Case 5b
bursitis lateral
bursitis marked lateral

Lateral view. An increased soft tissue density presents throughout the retrocalcaneal bursal recess and extends into Kager's fat pad. The arrow identifies a retrocalcaneal spur at the Achilles tendon enthesis; there also is an inferior calcaneal spur. Diagnoses: retrocalcaneal bursitis/enthesopathy.

Bursal recess normalbursal recess normal marked

Normal lateral views. The retrocalcaneal bursal recess (arrows) is located between the anterior margin of the Achilles tendon (white line) and the outer margin of the calcaneal bursal projection (the posterior-superior aspect of the calcaneus). It blends with Kager's fat pad.

haglund's deformity
parallel pitch lines

Lateral view. The parallel pitch line is positive, i.e., the top (arrow) of the bursal projection (BP) falls above the upper black line. Diagnosis: Haglund's deformity.

negative PPL

Lateral view. An example of a negative parallel pitch line (the bursal projection falls below the upper black line). The Fowler-Philip angle was a false positive, 77 degrees (the normal range falls between 45 and 70 degrees).

Bywater's erosion
bywater's erosion marked

Lateral view. The arrows identify well-defined erosions along the posterior aspect of the bursal projection. Diagnosis: rheumatoid arthritis (based upon DP radiographs of the forefoot and clinical history).

os trigonum
os trigonum marked

Lateral view. There is a well-defined ossicle (arrowhead) that articulates with the posterolateral process of the talus. Diagnosis: os trigonum.

saggital t1 sagittal STIR
sagittal t1 marked sagittal STIR marked

MRI sagittal T1 and STIR images. The T1 image (left) identifies anatomically that a separate ossicle (arrows) exists posterior to the posterolateral talar process. The STIR image (right) demonstrates high signal intensity (arrows) surrounding the ossicle; the ossicle itself reveals high signal intensity within it. Diagnosis: os trigonum syndrome. Images for Case 4b (without markings) courtesy of Joel Rozner.

stress fracture calcaneus
stress fracture calcaneus marked

Lateral view. Findings include an ill-defined increased density (white arrows) within the posterosuperior aspect of the calcaneus. Diagnosis: stress fracture. (The black arrow points to a well-defined, curvilinear increased density just above the medial tubercle; this is the inferior border of the lateral tubercle, a normal finding.)

mri calcaneal stress fracture MRI saggital stir
axial t2 marked saggital stir marked

MRI axial T2 (left) and sagittal STIR images. The linear low signal intensity (arrows) represents the fracture that is surrounded by high signal intensity (H) that corresponds to fluid (inflammation). Images for Case 5b (without markings) courtesy of Joel Rozner.

Should a radiographic study be ordered for retrocalcaneal pain?

Yes.

What are the best views to order?

At a minimum order the lateral view with one or more of the following:

  • calcaneal axial view and both oblique views (if suspicious of fracture posteriorly).
  • DP view (when inflammatory arthritis is suspected; order bilateral study).
  • both oblique views (for bursitis and Haglund's deformity).
  • lateral oblique view (for os trigonum syndrome or fracture of posterolateral talar process).
Are special studies valuable?

Yes; MRI can be valuable for further evaluation of all related pathology involving the retrocalcaneal region when clinically indicated.

Other information
Kager’s fat pad is bounded by the Achilles tendon posteriorly, the calcaneus inferiorly, and the flexor hallucis longus tendon anteriorly.

References:

  1. Resnick D: Bone and Joint Imaging, 2nd edition, WB Saunders, 1996.
  2. Christman RA: Foot and Ankle Radiology, 2nd edition, Lippincott Williams & Wilkins, 2015.
  3. Chauveaux D, Liet P, Le Huec JC, and Midy D: A new radiologic measurement for the diagnosis of Haglund's deformity. Surgical and Radiologic Anatomy 13(1):39-44, 1991.