From the Guidelines
A 5th metatarsal avulsion fracture should be initially treated with conservative management, including RICE protocol, weight-bearing limitation, and pain management with NSAIDs, as surgery is rarely needed unless the fracture is significantly displaced or conservative treatment fails. The diagnosis of a 5th metatarsal avulsion fracture is based on a history of trauma and focal pain on palpation, and is confirmed with radiographic studies 1. According to the American College of Foot and Ankle Surgeons, simple immobilization is appropriate when fracture fragments are small, nonarticular, or minimally displaced 1.
The initial imaging study for patients with suspected 5th metatarsal avulsion fracture should include radiographs of the foot, with a focus on the base of the fifth metatarsal bone distal to the tuberosity 1. The Ottawa rules for the foot can be used to determine the need for imaging, with a series of foot radiographs required only if there is pain in the midfoot and any one of the following: point bone tenderness of the navicular, point bone tenderness of the base of the fifth metatarsal, or inability to bear weight or to walk 4 steps 1.
Weight-bearing radiographs can provide important information, particularly with fractures of uncertain stability, and a medial clear space of <4 mm should confirm stability 1. The use of ultrasound or other advanced imaging modalities may not be necessary for the initial evaluation of a 5th metatarsal avulsion fracture, unless there are concerns about fracture stability or displacement 1.
In terms of treatment, most avulsion fractures heal well with conservative treatment, and surgery is rarely needed unless the fracture is significantly displaced (>2mm) or if conservative treatment fails. A hard-soled shoe or walking boot is recommended for protection during healing, and physical therapy may be beneficial after 4-6 weeks to restore strength and range of motion. Patients should follow up with imaging at 6-8 weeks to confirm healing.
Key points to consider in the management of a 5th metatarsal avulsion fracture include:
- Initial treatment with RICE protocol and weight-bearing limitation
- Pain management with NSAIDs
- Use of radiographs to confirm diagnosis and evaluate fracture stability
- Conservative management, with surgery rarely needed unless fracture is significantly displaced or conservative treatment fails
- Follow-up imaging at 6-8 weeks to confirm healing
- Consideration of physical therapy to restore strength and range of motion after 4-6 weeks.
From the Research
Definition and Classification of 5th Metatarsal Avulsion Fracture
- A 5th metatarsal avulsion fracture is a type of fracture that occurs at the base of the 5th metatarsal bone, which is the long bone on the outside of the foot that connects to the little toe 2.
- These fractures are commonly classified into three zones: zone A, zone B, and zone C, based on the location and mechanism of the fracture 2.
Treatment Options for 5th Metatarsal Avulsion Fracture
- Treatment options for 5th metatarsal avulsion fractures include conservative management with immobilization and weightbearing, as well as surgical management with open reduction and internal fixation 3.
- Conservative management may involve the use of a hard-soled shoe, controlled ankle motion (CAM) walker boot, or a below-knee walking cast 4, 5.
- Surgical management may be recommended for fractures that are displaced more than 2 mm, or for patients who have a high risk of nonunion 3.
Comparison of Treatment Outcomes
- Studies have compared the outcomes of different treatment options for 5th metatarsal avulsion fractures, including conservative management with a CAM walker boot versus a hard-soled shoe 4, and surgical management versus conservative management 3.
- One study found that patients treated with a CAM walker boot had faster bone healing and similar clinical and functional outcomes compared to those treated with a hard-soled shoe 4.
- Another study found that surgical management eliminated the risk of nonunion and allowed for a timely return to preinjury activity, but that conservative management was also effective for some patients 3.
Patient Outcomes and Recovery
- Patient outcomes and recovery times can vary depending on the treatment option chosen and the individual patient's characteristics 5, 6.
- One study found that patients treated with a walking boot had less pain and better function at 3,6, and 9 weeks after injury compared to those treated with a short-leg cast 5.
- Another study found that symptomatic treatment was non-inferior to cast immobilization in terms of patient-reported outcome measures, but that there was significant loss to follow-up at 6 months 6.