Cuboid Stress Fractures

Although less common than fractures in other bones of the foot, cuboid stress fractures can lead to significant discomfort and mobility issues, especially for active individuals. These fractures result from repetitive stress on the cuboid bone, located on the foot’s outer side between the heel and the base of the fourth and fifth metatarsals. Proper diagnosis and treatment are essential to ensure optimal healing and prevent further injury.

1. Anatomy of the Cuboid Bone and the Mechanics of Stress Fractures

The cuboid bone, a key part of the midfoot, is essential in stabilising the foot and maintaining arch integrity. It connects the calcaneus (heel bone) to the fourth and fifth metatarsals and aids in transferring weight and distributing force throughout the foot when walking, running, or jumping. Unlike acute fractures, which result from a single traumatic event, stress fractures develop gradually due to repetitive, low-impact forces that lead to microscopic cracks in the bone.

2. Causes of Cuboid Stress Fractures

Cuboid stress fractures can arise from a combination of intrinsic and extrinsic factors:

• Overuse and Repetitive Strain: The most common cause of cuboid stress fractures is repetitive strain, often from activities like running, dancing, or sports that involve sudden, repetitive lateral foot movements. Over time, the constant loading of the cuboid weakens the bone, causing small cracks to develop.
• Improper Foot Biomechanics: Foot mechanics play a significant role in cuboid stress fractures. People with flat feet or overpronation (excessive inward rolling of the foot) may strain the cuboid bone more, increasing susceptibility to stress fractures. On the other hand, high arches can reduce shock absorption, putting more pressure on the cuboid.
• Footwear and Training Surface: Wearing unsupportive or worn-out shoes can exacerbate the strain on the foot, particularly the cuboid bone. Running on hard or uneven surfaces also increases impact forces and can lead to stress fractures over time.
• Sudden Increase in Activity Level: Increasing workout intensity or duration too rapidly doesn’t allow the bones to adapt to new forces, making the cuboid prone to stress injuries.
• Nutritional Deficiencies and Bone Health: Inadequate calcium, vitamin D, or other essential nutrients weaken bone density, increasing the likelihood of fractures.
• Previous Foot or Ankle Injuries: A history of foot or ankle injuries, such as ankle sprains, may lead to compensatory movements that stress the cuboid bone.

3. Diagnosis of Cuboid Stress Fractures

Diagnosing a cuboid stress fracture can be challenging due to its deep location and because the symptoms often overlap with other foot conditions. A thorough medical history, physical examination, and imaging studies are essential.

• Clinical Examination: Patients typically present with localised pain on the foot’s outer side, which may worsen with weight-bearing activities. There may also be tenderness along the cuboid bone, especially when pressing on the midfoot’s lateral (outer) aspect. Pain often intensifies with certain foot movements, like inversion (turning the foot inward) or eversion (turning the foot outward).
• Imaging Studies:
• X-rays: While X-rays are often the first imaging choice, they may not immediately detect stress fractures in the cuboid, especially in the early stages. Small cracks may only become visible weeks after symptoms begin.
• MRI (Magnetic Resonance Imaging): An MRI is more sensitive than an X-ray and is often used to confirm a stress fracture. It can detect soft tissue inflammation around the fracture, making it useful for early detection.
• CT Scan (Computed Tomography): CT scans provide detailed images of the bone structure and can help assess the extent and exact location of the fracture if necessary.

4. Treatment Options for Cuboid Stress Fractures

The treatment of cuboid stress fractures depends on the severity of the fracture, patient activity level, and overall health. Treatment typically focuses on rest, protection, and rehabilitation.

Conservative (Non-Surgical) Treatment

Most cuboid stress fractures can be effectively managed with conservative measures:

• Rest and Activity Modification: It is crucial to reduce or stop activities that place stress on the foot. High-impact exercises should be avoided to allow the bone to heal. Cross-training activities that place less strain on the foot, like swimming or cycling, may be recommended.
• Immobilisation:
• Walking Boot or Cast: A walking boot or cast may be prescribed to immobilise the foot and minimise weight-bearing on the cuboid. This immobilisation is usually maintained for 4–6 weeks, depending on the severity of the fracture.
• Crutches: Partly or non-weight-bearing with crutches may be advised to further reduce stress on the cuboid bone for more severe fractures.
• Orthotics and Supportive Footwear: Custom orthotics or insoles can provide arch support, offloading pressure from the cuboid. Supportive footwear that stabilises the foot and minimises lateral movements is also recommended to prevent future injury.
• Pain Management: Over-the-counter pain relievers, like paracetamol, can help manage pain during healing. Nonsteroidal anti-inflammatory drugs (NSAIDs) are generally avoided, as they may interfere with bone healing.
• Physical Therapy: Once the fracture has healed, physical therapy is crucial to restore strength, flexibility, and stability. Exercises may focus on the intrinsic muscles of the foot, calf, and lower leg to improve support around the cuboid bone.

Surgical Treatment

Surgery is rarely needed for cuboid stress fractures, but it may be considered in severe or non-healing cases where conservative treatments have failed. Surgical options typically involve stabilising the cuboid bone with internal fixation, such as screws or plates. After surgery, a period of immobilisation and gradual return to activity is necessary, similar to conservative treatment protocols.

5. Rehabilitation and Prevention

Rehabilitation focuses on safely returning to activity without re-injury. A gradual increase in activity levels and a focus on strengthening exercises are key. Proper training, wearing supportive footwear, and addressing any biomechanical abnormalities are also key to preventing future cuboid stress fractures.

• Strengthening Exercises: Rehabilitation includes strengthening the foot and ankle muscles, stabilising the arch, and reducing excess strain on the cuboid. Resistance band exercises, balance training, and toe curls are helpful.
• Stretching: Stretching the calf muscles, Achilles tendon, and plantar fascia can improve flexibility and reduce tension in the foot.
• Gradual Return to Activity: A slow progression in exercise intensity is recommended, allowing the bones and muscles time to adapt to increased demands. High-impact activities should be reintroduced cautiously.
• Addressing Biomechanical Issues: Custom orthotics are advised for those with flat feet or high arches to improve foot alignment and prevent excess strain on the cuboid.