Where is the subtle physeal injury located in the ankle?

Locating Subtle Physeal Injury in the Ankle

The subtle physeal injury is most commonly located in the distal tibia, particularly at the medial malleolus, where physeal fractures can be difficult to detect on standard radiographs. 1

Anatomy and Common Locations of Physeal Injuries

• The distal tibial physis initially appears as a relatively transverse structure but develops undulations as the epiphysis matures, with a significant anterior undulation above the medial malleolus within the first two years of life 2
• Physeal injuries account for approximately 15% of all childhood fractures, with 10% of these being sports-related 3
• The most common location for subtle physeal injuries is the medial malleolus of the distal tibia, where Salter-Harris type I and II fractures can be easily missed on standard radiographic views 1
• The distal fibular physis becomes a convoluted structure with extensive peripheral lappet formation, which can make subtle injuries difficult to detect without stress views 2

Diagnostic Challenges

• Subtle physeal injuries may present with less intense pain compared to other fractures, but will typically show swelling, hyperemia, and possible deformity in the physeal area 3
• Fractures extending into the metaphysis (particularly in Salter-Harris type IV injuries involving the medial malleolus) may only be appreciated on oblique radiographic views 4
• In the presence of a suspected physeal injury with negative standard radiographs, MRI is the most sensitive imaging modality for detection 5
• Subtle physeal injuries at the lateral portion of the distal tibial epiphysis (Tillaux fracture) and triplane fractures are predisposed by the pattern of physiologic epiphyseodesis that begins over the medial malleolus and extends laterally 2

Imaging Approach for Subtle Physeal Injuries

• Standard radiographic protocols should include anteroposterior, lateral, and mortise views 5
• Special views that may help identify subtle physeal injuries include:
  • Oblique views - critical for identifying extension of fractures into the metaphysis, especially in medial malleolar injuries 4
  • Stress views - may be necessary to demonstrate undisplaced physeal fractures, particularly in the distal fibula 2
• MRI without IV contrast is the most sensitive imaging modality for detecting occult physeal fractures with associated bone marrow edema patterns 5
• MRI can help exclude Salter-Harris type I fractures in the pediatric population that may be radiographically occult 5
• CT may be useful for evaluating complex fracture patterns and determining the extent of injury in displaced physeal fractures 5

Clinical Significance and Outcomes

• Missed or inadequately treated physeal injuries can lead to premature partial closure of the physis, resulting in angular deformity or limb-length discrepancy 4
• Salter-Harris type III and IV fractures, particularly those involving the medial malleolus, have a higher risk of growth disturbance and require precise anatomic reduction 1
• Long-term follow-up studies show that the type of Salter-Harris lesion, amount of initial displacement, and quality of reduction are the main parameters determining outcomes 6
• Radiographic signs of osteoarthritis were present in 11.8% of patients with physeal injuries in long-term follow-up, predominantly in those with Salter-Harris type III or IV lesions 6

Management Considerations

• Nondisplaced physeal fractures of the distal tibia and fibula can be safely treated nonoperatively with immobilization 1
• Displaced fractures should undergo gentle reduction with appropriate anesthesia, avoiding multiple reduction attempts 1
• Gapping of the physis >3 mm after reduction should raise suspicion of entrapped periosteum, which increases the risk of premature physeal closure 1
• Open reduction is critical for displaced Salter-Harris type III and IV fractures to maintain joint congruity and minimize the risk of physeal arrest 1