Avulsion fracture of the 5th metatarsal styloid, also known as a pseudo-Jones fracture, is one of the more common foot avulsion injuries, and accounts for over 90% of fractures of the base of the 5th metatarsal.
Despite what should be a simple entity, controversy exists, as well as confusion in the literature, with the term Jones fracture sometimes liberally (and incorrectly) applied to this fracture.
Traditionally this avulsion fracture has been ascribed to the insertion of peroneus brevis and is caused by forcible inversion of the foot in plantar flexion, as may occur while stepping on a curb or climbing steps. It is for this reason that the 5th metatarsal base must be included in the lateral ankle projection of an ankle series, especially when performed for an inversion injury.
It is also relatively common among tennis players, accounting for it sometimes being referred to as a "tennis fracture".
Some authors believe that it is due to the lateral cord of the plantar aponeurosis which also inserts at the base, rather than the peroneus brevis tendon 2.
Small fracture usually of the tip of the proximal 5th metatarsal, oriented mostly transversely (cf. apophysis which parallels the shaft). It usually does not reach the articular surface (metatarsocuboid), but occasionally does.
In some instances the fracture may be occult.
Treatment and prognosis
In general these fractures can be treated conservatively, and heal well 2. For large or very displaced fragments with intra-articular extension then operative fixation may be indicated.
A number of fractures occur at the base of the 5th metatarsal (see fractures of the proximal fifth metatarsal) as well as entities that mimic fractures:
- 1. Stevens MA, El-khoury GY, Kathol MH et-al. Imaging features of avulsion injuries. Radiographics. 19 (3): 655-72. Radiographics (full text) - Pubmed citation
- 2. Richli WR, Rosenthal DI. Avulsion fracture of the fifth metatarsal: experimental study of pathomechanics. AJR Am J Roentgenol. 1984;143 (4): 889-91. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. “Avulsion Frx of Base of 5th Metatarsal - Wheeless' Textbook of Orthopaedics.” [Link].
- 4. Theodorou DJ, Theodorou SJ, Kakitsubata Y et-al. Fractures of proximal portion of fifth metatarsal bone: anatomic and imaging evidence of a pathogenesis of avulsion of the plantar aponeurosis and the short peroneal muscle tendon. Radiology. 2003;226 (3): 857-65. doi:10.1148/radiol.2263020284 - Pubmed citation