Clin Orthop Surg.  2012 Jun;4(2):134-138. 10.4055/cios.2012.4.2.134.

Avulsion Fracture of the Calcaneal Tuberosity: Classification and Its Characteristics

• Lee SM
• Huh SW
• Chung JW
• Kim DW
• Kim YJ
• Rhee SK

• KMID: 1383875
• DOI: http://doi.org/10.4055/cios.2012.4.2.134

Abstract

BACKGROUND
Not much is known regarding avulsion fractures of the calcaneal tuberosity. We propose a modified classification scheme that presents the four types of calcaneal avulsion fracture as described by surgical and magnetic resonance imaging (MRI) findings, and evaluation of their specific features.
METHODS
Out of 764 cases of calcaneal fractures, we examined 20 cases (2.6%) that involved the tuberosity of the calcaneus. Each case was classified depending on the avulsed fracture patterns as follows; type I is a 'simple extra-articular avulsion' fracture, type II is the 'beak' fracture, type III is an infrabursal avulsion fracture from the middle third of the posterior tuberosity, and finally in type IV there is the 'beak', but a small triangular fragment is separated from the upper border of the tuberosity. We examined the features of each avulsed type according to several criteria including patient age, gender, anatomical variances of the Achilles tendon, the fibers involved and the mechanism of injury.
RESULTS
The type I fracture (8/20 cases) was the most common and likely to occur in elderly women. However, in other types, they were more common in relatively younger male patients. Type I were usually caused due to an accidental trip causing a fall by the patient. However, the dominant cause of type II (5/20 cases) fractures a direct blow or hit directly to the bone. Type III (4/20 cases) and IV (3/20 cases) fractures were likely to occur due to falling. All fibers within the Achilles tendon are involved in both type I and II fractures. However, only the superficial fibers are involved in type III fractures, whereas the deep fibers are involved in type IV fractures.
CONCLUSIONS
The avulsion patterns of the calcaneal tuberosity fractures are the result of several factors including the bony density level, the mechanism of injury and the fibers of the Achilles tendon that transmit the force. Accurate diagnosis of type III and IV is dependant on MRI technology to confirm the specific location of the injury and provide proper patient treatment therapeutics.

Keyword

Achilles tendon; Calcaneal tuberosity; Avulsion fracture

MeSH Terms

Adolescent
Adult
Age Factors
Aged
Calcaneus/*injuries/pathology/radiography
Child
Female
Fractures, Bone/*classification/pathology/radiography
Humans
Male
Middle Aged
Statistics, Nonparametric

Figure

• 

  Fig. 1 Classification of avulsion fracture of the calcaneal tuberosity. Type I: simple extra-articular avulsion, Type II: beak fracture, Type III: infrabursal avulsion involving superficial fibers of Achilles tendon, Type IV: beak, but a small triangular fragment involoving deep fibers of Achilles tendon.

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  Fig. 2 The involved fibers of the Achilles tendon according to the fracture type. (A) In type III fracture, only the superficial fibers are involved with the avulsed fracture fragment (*), and the deep fibers of the Achilles tendon are intact. (B) In contrast to type III fracture, only the deep fibers are involved in type IV fracture (*avulsed portion).

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  Fig. 3 Characteristics of the avulsion fracture of the calcaneal tuberosity and recommended treatment.

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