Fifth Metatarsal Fracture

What Is Fifth Metatarsal Fracture?

Fifth Metatarsal Fracture is one of the most common metatarsal fractures. Metatarsals carries a major role in the body for it is a weight bearing structure that is located in the forefoot. There is complex relationship between metatarsals and they should work well together so that they can give an ideal biomechanical foot function.

The fifth metatarsal has a unique blood supply and good biomechanical function that make it more complex for fracture considerations than other lesser metatarsals.

Anatomy of the Fifth Metatarsal

The fifth metatarsal is a fracture that has less soft tissue coverage and very intrinsic muscle attachments than the other lesser metatarsals. The fifth metatarsal plays a major important role in the body by maintaining the tripod effect of the foot with calcaneus and first metatarsal. It is the very most mobile of the metatarsals.

The fifth metatarsal has extrinsic muscle attachments that include the peroneus brevis, tertius and the lateral band of plantar fascia. The blood flow and supply of the fifth metatarsal plays an important role in determining the treatment algorithms.

The fifth metatarsal is supplied blood by the arterial branches from the dorsalispedis, posterior tibial and the peroneal arteries. The nutrient artery originates from the fourth plantar metatarsal artery and then it inserts into the plantar medial diaphysis of the metatarsal in approximately 80% of individuals.

The metadiaphyseal region of the fifth metatarsal is very vulnerable to non-union rates due to anatomic location of the blood supply which results in this watershed zone.

Mechanism

The fifth metatarsal has the most motion through the TMT articulation when compared to the other four metatarsals. The fifth TMT articulation is very important as it plays a major role in accommodative functionof the lateral column.

Increased motion throughout the Fifth Metatarsal Fracture TMT articulation allows accommodative nature of the foot position during the gate cycle so that the foot can function optimally.

Causes

Fifth metatarsal fractures can occur due to a variety of low and high energy mechanisms. Low energy mechanisms include;

Stress response
Twisting injuries on the foot.

High energy mechanisms include:

Lawn mowing injuries
Industrial accidents.

There are two names that are commonly used to describe fifth metatarsal fractures. They include Dancer’s and Jones fractures.

Dancer’s fractures occur due to inversion injuries therefore involving the shaft of the metatarsal. These fractures can heal well when minimally displaced by treating them non-operatively.
Jones fractures occur at the meta-diaphyseal region which is a relative avascular zone which increases the non-union rates. Stress fractures also occur in the meta-diaphyseal region.

Metatarsal base fractures occur when there is an inversion strain in the lateral plantar aponeurosis. The metatarsal base fractures can also occur in the cancellous region of the MT.

Clinical Presentation

Patients with stress related injuries usually describe a prodrome of pain that is present for weeks to months leading to complete fractures that require medical attention.

Other common injuries include a forced abduction of force of the forefoot with ankle planarflexion.

Many acute Jone’s fractures mostly occurs in athletes giving important implications in treatment and the length of immobilization.

How To Examine?

The fifth metatarsal fracture can occur to persons of any age. Most injuries are usually closed but high energy injuries such as lawn mowing injuries can open fractures.

Metatarsal fractures appears to have dorsal soft tissue swelling and ecchymosis and pain due to weight bearing.
If the fracture is caused by high energy mechanisms, the examiner should pay attention to the neurovascular exam and both the TMT and MTP articulations.
In case of any disorders with the foot or the ankle, a thorough examination should be performed that includes full inspection, palpation, ROM, sensory and vascular exams.
If the patient is able to, a gait analysis and testing the positions of the lower extremities should also be performed with the patient weight bearing.

Stages

There are three classification for metatarsal; the head, neck and the shaft fractures. These fracture locations can heal well with conservative treatments.

There are three zones classified for proximal metatarsal fractures:

Zone 1- It involves the fifth metatarsal tuberosity.
Zone 2- Involves the proximal metaphyseal-diaphyseal junction without distal extension beyond the fourth and fifth inter-metatarsal articulation or the acute Jones fractures.
Zone 3- It describes the diaphyseal fractures or the classic “dancer’s fractures.”

Imaging Studies

Studies that have been made show that the plain radiographs are the mainstay of the imaging modalities for the fifth metatarsal fractures.

Close attention to the anatomic location of the proximal fractures guides the physician to better and good treatment algorithms. Examiners should evaluate the lateral metatarsal for thickening that could indicate there is a healing stress response of fracture.

Treatment

For most metatarsal head, neck and shaft fractures, conservative treatment is the treatment of choice. It involves non-operative treatment in a cast for six weeks. They may take longer to heal but as long as there is progression of healing there is minimum pain and the patient can wear regular shoes on the sixth week after the injury.

Surgery is indicated for non-unions and any significant fracture displacement which is common in the anatomic location. Also surgery is done for fractures with any prodrome pain.

Elite athletes who wish to avoid prolonged immobilization with many conservative treatments and operative intervention can be considered for treatment of choice.

If there is any persistent pain even after three months of conservative treatment, an operative treatment for the fracture should be considered.

Conclusion

All the fifth metatarsal fractures require to be evaluated and treated carefully so as to prevent any further damage. The fifth ray is very important to the function of the forefoot and the biomechanics of the tripod foot.

The inherent blood supply and the structure of the fifth metatarsal guide all treatment algorithms.

It is very essential for the physician treating the fracture to understand the complications that are involved when treating any fifth metatarsal fracture so as to give the best treatment for the fracture.

Reference List

Fractures of the fifth metatarsal. https://www.foothealthfacts.org/conditions/fractures-of-the-fifth-metatarsal
Fifth metatarsal bone: https://en.wikipedia.org/wiki/Fifth_metatarsal_bone
How To Treat Proximal Fifth Metatarsal Fractures. http://www.healio.com/
Fifth Metatarsal Fractures. http://www.aofas.org/PRC/conditions/Pages/Conditions/Fifth-Metatarsal-Fractures.aspx
Fifth metatarsal fractures and current treatment. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155254/
Diagnosis and Management of Metatarsal Fractures. http://www.aafp.org/afp/2007/0915/p817.html
Metatarsal Fractures. https://patient.info/health/metatarsal-fractures