Can a 25-year-old female with a non-displaced posterior malleolus fracture and no significant past medical history bear weight as tolerated in a Controlled Ankle Movement (CAM) walker boot?

Weight-Bearing Protocol for Non-Displaced Posterior Malleolus Fracture

Yes, a 25-year-old female with a non-displaced posterior malleolus fracture can bear weight as tolerated immediately in a CAM walker boot. 1

Primary Recommendation

Immediate full weight-bearing as tolerated in a CAM walker boot is appropriate for this patient, based on the American Academy of Orthopaedic Surgeons guidelines for stable, non-displaced ankle fractures. 1

• The key determinant is fracture stability, which must be confirmed before allowing weight-bearing 1
• Non-displaced fractures with maintained ankle mortise alignment (medial clear space <4 mm) are considered stable and suitable for immediate weight-bearing 1

Critical Stability Assessment Required

Before implementing weight-bearing, confirm the following on imaging:

• Medial clear space must be <4 mm on standard radiographs - this is the most important criterion for ankle stability 1
• Standard three-view radiographs (anteroposterior, lateral, and mortise views) should be obtained to properly assess stability 1
• Weight-bearing radiographs are preferred as they can detect dynamic abnormalities such as joint mal-alignment or subluxation not apparent on non-weight-bearing films 2, 1

Exclusion Criteria That Would Alter Management

Do NOT allow weight-bearing as tolerated if any of the following are present:

• Medial tenderness, bruising, or swelling suggesting deltoid ligament injury 1
• Bi- or trimalleolar fractures 1
• Fracture displacement >2 mm 1
• Ankle mortise instability (medial clear space >4 mm) 1
• High-energy mechanism of injury 1

Implementation Protocol

Immediate weight-bearing progression:

• Allow full weight-bearing as tolerated immediately in a removable CAM walker boot 1
• Assistive devices (crutches) may be used initially for comfort but are not mandatory if the patient tolerates full weight-bearing 1
• The removable boot provides adequate protection while allowing early mobilization 1

Supporting Evidence and Rationale

The recommendation for immediate weight-bearing in stable ankle fractures is supported by multiple lines of evidence:

• Early weight-bearing after posterior malleolar fracture fixation facilitates recovery, promotes fracture union, and allows patients to resume normal activity by the third month 3
• Biomechanical studies demonstrate that the posterior one-fourth of the ankle joint remains relatively unloaded during normal weight-bearing, particularly in neutral and plantarflexed positions 3
• A study of immediate weight-bearing after ankle fracture fixation in selected patients showed only 1/26 patients had loss of fixation, which was attributed to a missed syndesmotic injury rather than the weight-bearing protocol 4
• Patients treated with immediate weight-bearing protocols return to activities of daily living faster and may facilitate rehabilitation 4

Follow-Up Recommendations

Clinical monitoring schedule:

• Patients should return for re-evaluation if discomfort worsens or does not improve 1
• Follow-up imaging should be obtained to ensure maintenance of reduction and progressive healing 1
• If any evidence of displacement or instability appears on follow-up imaging, the weight-bearing status must be reassessed immediately 1

Common Pitfalls to Avoid

Critical errors in management:

• Do not rely solely on initial non-weight-bearing radiographs - obtain weight-bearing views when possible to assess dynamic stability 2, 1
• Do not miss associated syndesmotic injury - this was the cause of the single fixation failure in the immediate weight-bearing study 4
• Do not overlook subtle medial-sided injuries - even with isolated lateral or posterior malleolar fractures, deltoid ligament disruption can occur and requires different management 5
• In patients with positive stress testing (≥5 mm medial clear space widening), MRI may be needed to evaluate deltoid ligament integrity before allowing weight-bearing 5

Special Considerations for This Patient Population

For a young, healthy 25-year-old female without comorbidities:

• Early weight-bearing prevents muscle atrophy and joint stiffness while maintaining functional independence 1
• The absence of diabetes, neuropathy, or osteoporosis makes this patient an ideal candidate for immediate weight-bearing 1
• By 6 weeks, most patients in this demographic can transition to normal shoes if comfortable 4