We present three cases outlining the normal variants and trauma to the base of the 5th metatarsal.
We present a case of a fracture through the base and apophysis of the 5th metastarsal in a 13-year-old boy following an ankle trauma. Further examples of the normal anatomy and fractures are given, to draw attention to the possibility of confusion of the normal findings with pathology in this region.
The mechanism for fracture in this region is usually a forced inversion causing an avulsion of the base of the 5th metatarsal. A clinical assessment is often made using the Ottawa rules (Steill et al.), which were more recently discussed in a systematic review (Bachmann et al.). Midfoot views are only generally requested when there is a specific concern, like tenderness of the base of the 5th metatarsal. Nevertheless, the 5th metatarsal is generally included on the lateral ankle view, so that an obvious fracture can be identified even when it is clinically not suspected. Our case is one of an unusual fracture through the apophysis and base of the 5th metatarsal. The subsequent film shows a simple base fracture as a clear transverse break in the cortex and an accompanying soft tissue swelling. The final film demonstrates a normal apophysis with the longitudinal lucent line at the base. The important radiological feature is that fractures tend to run transversely across the base while the physeal line is longitudinal. The fractures are generally related to the peroneus brevis tendon coming under stress. It is important to note that these fractures are not "Jones" fractures. Jones fractures involve the proximal shaft of the metatarsal and not the base, and do not relate to avulsion by the peroneus brevis tendon (Rodgers). Jones fractures should be properly distinguished, as they can often require surgical intervention. Avoiding misdiagnoses in this region is extremely important to avoid unnecessary treatment and to provide follow-up as guided, in the case of a Jones fracture.
Fracture through the apophysis of the 5th metatarsal base.
Based on the provided foot X-ray, an abnormal bony structure is observed at the base of the 5th metatarsal of the right foot. Specific findings are as follows:
1. On the lateral side of the foot (the base of the 5th metatarsal), cortical disruption appears as a near-transverse or slightly oblique radiolucent line, accompanied by local soft tissue swelling.
2. In contrast with normal anatomical variations: in children and adolescents, a longitudinal radiolucent line parallel to the shaft (the apophyseal plate, also referred to as the apophysis) can appear at the base of the 5th metatarsal, which differs in orientation from a true fracture line.
3. No significant involvement of the proximal 5th metatarsal shaft or clear signs suggesting a Jones fracture (which usually appears at the junction between the proximal shaft and the metaphysis of the 5th metatarsal).
4. No obvious bony abnormalities seen in other metatarsals or tarsal bones; some localized soft tissue swelling is visible, mainly confined to the lateral plantar area.
Considering the patient's age (13 years old, with open growth plates), mechanism of injury (eversion or twisting can overload the base of the 5th metatarsal), and imaging characteristics, the potential diagnoses or differential diagnoses include:
1. Avulsion Fracture of the 5th Metatarsal Base: This is most commonly seen with foot eversion or ankle sprains, where the fibularis (peroneal) tendons pull on the metatarsal base, leading to a transverse or oblique fracture line with associated soft tissue swelling.
2. Normal Apophysis or Growth Plate: In children and adolescents, a growth plate can be seen in this region, depicted as a radiolucent line parallel to the longitudinal axis of the bone; this should not be mistaken for a true fracture line.
3. Jones Fracture: Typically involves the junction of the proximal 5th metatarsal shaft and metaphysis; the fracture line may be transverse or slightly oblique but is located farther from the joint surface. Due to limited blood supply, it has a higher risk of nonunion, requiring differentiation from an avulsion fracture.
Combining the patient’s age, clinical symptoms (history of trauma, lateral foot pain and tenderness), and imaging findings (transverse cortical disruption at the base of the 5th metatarsal along with soft tissue swelling), the most likely diagnosis is: Avulsion Fracture at the Base of the 5th Metatarsal (an atypical avulsion involving the apophyseal region), rather than a Jones fracture.
1. Treatment Strategies
- Conservative Treatment: Most simple avulsion fractures may be managed with casting or bracing to limit weight-bearing for 4–6 weeks, facilitating bony healing. If there is no or minimal displacement, conservative treatment is suitable; monitor healing progress during this period.
- Surgical Treatment: If there is significant displacement of the fracture fragment, instability, or involvement of the articular surface, referral to orthopedics for potential surgical fixation should be considered.
- Observation & Follow-up: Conduct regular X-ray evaluations to monitor fracture healing and apophyseal development, ensuring no malunion or delayed union occurs.
2. Rehabilitation and Exercise Prescription (FITT-VP Principle)
• F (Frequency): After cast or brace removal and confirmation of stable healing, it is recommended to perform rehabilitation exercises 3–4 times per week.
• I (Intensity): Begin with mild weight-bearing and low-intensity proprioceptive training, avoiding high-impact activities. Increase load and intensity gradually as pain subsides and the fracture becomes stable.
• T (Time): Each session can last 20–30 minutes, adjusted according to fatigue and pain levels. Allow rest days or engage in low-intensity activities in between sessions.
• T (Type): Exercises may include:
(1) Simple active ankle movements and toe flexion/extension;
(2) Gentle balance and proprioception training (e.g., single-leg standing, balance pad exercises);
(3) Gradual strengthening exercises for the fibularis (peroneal) muscles (e.g., resistance band eversion training);
(4) Light jogging and jumping drills in the final phase, under professional supervision.
• V (Volume): Start with low to moderate volume, gradually increasing based on pain and fatigue levels for each session.
• P (Progression): Closely monitor local pain and swelling, and progress gradually in difficulty and intensity. Since adolescent growth plates are still open, avoid excessive loading to prevent reinjury.
During the rehabilitation process, take note of the following:
- If you experience severe foot pain, significant swelling, or persistent worsening of symptoms after exercise, seek re-evaluation promptly.
- Adjust the plan according to fracture healing and individual fitness, maintaining adequate foot stability with supportive devices or footwear as needed.
- In adolescents, special attention should be paid to possible malunion or growth plate injuries due to ongoing skeletal development.
Disclaimer: This report is for reference only and cannot replace an in-person consultation or professional medical advice. If you have any questions or changes in condition, please seek medical attention or consult a healthcare professional promptly.
Fracture through the apophysis of the 5th metatarsal base.
