Is a cam (controlled ankle movement) boot a suitable treatment option for a non-displaced distal fibula fracture?

CAM Boot for Non-Displaced Distal Fibula Fractures

A CAM (controlled ankle movement) boot is an appropriate and effective treatment option for non-displaced distal fibula fractures, offering adequate immobilization while allowing for earlier mobilization compared to traditional casting. This approach aligns with modern fracture management principles that balance stability with functional recovery.

Treatment Rationale

Non-displaced distal fibula fractures can be successfully managed non-operatively with immobilization devices that provide adequate ankle stability. 1 The key principle is achieving sufficient immobilization to allow fracture healing while minimizing complications from prolonged immobility.

Why a CAM Boot Works

• Knee-high immobilization devices effectively offload and immobilize the ankle joint, redistributing ground reactive forces proximally and minimizing deforming effects of lower limb muscles on the ankle. 1
• The boot provides comparable fracture stability to casting while offering practical advantages including removability for skin inspection and hygiene. 1
• Immobilization prevents progressive deformity and promotes optimal fracture healing, particularly important in preventing malalignment and non-union. 1

Critical Implementation Details

Application Requirements

• The boot must be in close contact with the entire foot and lower limb to provide adequate immobilization. 1
• Insoles should accommodate any foot deformity safely and provide pressure redistribution to prevent skin breakdown. 1
• Consider rendering the boot temporarily non-removable (using cast wrap or tie wrap) if patient adherence is questionable, as non-adherence can lead to delayed healing and progressive deformity. 1

Immediate Concurrent Management

Begin active toe motion exercises immediately to prevent digital stiffness, which is functionally disabling and difficult to treat after fracture healing. 2, 3 This does not adversely affect adequately stabilized ankle fractures. 3

Common Pitfalls to Avoid

• Do not restrict toe/finger motion - failure to encourage immediate digital range of motion leads to significant stiffness requiring extensive therapy. 2, 3
• Monitor for skin breakdown carefully - in patients with sensory neuropathy or diabetes, improperly fitted boots can cause ulceration in up to 14% of cases. 1
• Ensure patient understanding of adherence importance - removable devices have a median 3-month longer time to healing when patients don't wear them consistently. 1
• Watch for non-adherence red flags - patients may remove the boot prematurely due to minimal pain, leading to delayed healing or displacement. 1

Follow-Up Protocol

• Obtain repeat radiographs at 10-14 days to ensure fracture position is maintained. 2
• Assess for persistent or worsening pain during the first few weeks, which should prompt immediate reevaluation. 2
• Typical immobilization duration is 3-6 weeks depending on fracture healing progression and patient factors. 1

When to Consider Alternatives

Operative fixation should be considered if:

• The fracture displaces despite adequate immobilization 1
• There is associated deltoid ligament disruption with talar shift that doesn't reduce with fibular alignment 4
• The patient has multiple comorbidities making prolonged immobilization particularly risky 5, 6