Jones Fracture- Fracture of the 5th Metatarsal Bone

A British surgeon named Sir Robert Jones sustained an acute fracture at the base of the fifth metatarsal bone while dancing. This then prompted the Jones fracture to be named after him.

Jones fractures occur at the metaphyseal/diaphyseal junction. The fracture extends into the intermetatarsal joint proximal to the metatarsocuboid joint. The intermetatarsal joint articulates with the fourth metatarsal and the metatarsocuboid joint articulates with the cuboid bone. In order for the Jones fracture to be called so, the fracture must enter the intermetatarsal joint, which means the fracture must also be distal to the metatarsaocuboid joint.

Jones fractures occur about 1.5 cm distal to the tuberosity of the fifth metatarsal bone. This metatarsal bone is divided into the head, the neck, the shaft, and the tuberosity. Jones fractures of the proximal fifth metatarsal occurs in the watershed area within 1.5 cm of the tuberosity. This means that the fracture occurs in an area of limited blood supply. There are multiple metaphyseal arteries in the tuberosity. There is also a nutrient artery with intramedullary branches that provides retrograde blood flow to the proximal fifth metatarsal. Therefore, a fracture distal to the tuberosity will disrupt the nutrient artery supply, resulting in relative avascularity.

The peroneus tertius tendon is inserted into the dorsal metaphysis of the fifth metatarsal bone. Then, the peroneus brevis tendon is inserted into the tuberosity of the fifth metatarsal bone. The plantar fascia is also connected to the fifth metatarsal bone. Therefore, when a Jones fracture occurs, the tendons will pull the fracture apart, which will prevent healing.

There are three types of fractures at the proximal fifth metatarsal. A fracture in zone I is called a tuberosity avulsion fracture. A fracture in zone II is called a Jones fracture. Finally, a fracture in zone III is usually a stress fracture. A fracture in zone I is also called a pseudo Jones fracture. It is located at the peroneus brevis insertion site, and is usually treated with conservative treatment. Zone II Jones fractures occur at the metaphyseal-diaphyseal junction, and involve the fourth and fifth metatarsal articulation. Zone III stress fractures are chronic fractures that occur distal to the fourth and fifth metatarsal articulation, and may be associated with cavovarus foot deformity. It is important to not make the wrong diagnosis of the proximal fifth metatarsal base in children while looking at a normal growth plate. This is usually present between the ages of 9–14 years of age and is parallel and lateral to the metatarsal.

X-rays will show the fracture and its location. An acute Jones Fracture will have sharp margins with no intramedullary sclerosis. On the other hand, a stress fracture will have a wide fracture line with medullary sclerosis.

The treatment of Jones fractures is different depending on the severity of the fracture. A nondisplaced fracture is treated with a boot or cast and non-weightbearing status for 6–8 weeks. 75% of patients will heal using this method. However, if the fracture is displaced or in athletes, screw fixation of the fracture should be performed.

For surgery purposes, the lateral view appears to be straight and narrow. In the AP view, the fifth metatarsal appears to be curved, which is called a lateral bow. Lateral bow of the fifth metatarsal may cause complications during surgery. Also, there is vulnerability at the midshaft for perforation of the medial cortex. The canal is narrower in the dorsal plantar dimensions, which will appear narrow in the lateral view. The point of entry of the wire or the screw is not centered. This is due to the fifth metatarsocuboid joint that blocks the proximal canal projection, which can also cause complications. Each patient’s metatarsal should be evaluated on an individual basis for proper screw selection.

To perform screw placement, drill parallel with the shaft in the lateral plane and avoid the plantar direction. Caution should also be taken to avoid the sural nerve during surgery. A 4.5 mm cancellous screw is probably needed, and the probable appropriate length of the screw is around 40–50 mm. The diameter of the screw depends on the width of the canal. However, with a smaller screw, the fixation is unstable, but a larger screw may displace the fracture. The screw thread must cross the fracture site. Failure of the procedure is attributed to poor blood supply or return of an athlete to activity before complete radiographic union.