What are the radiographic findings for pes cavus and apophysitis of the distal tibia?

Radiographic Findings for Pes Cavus and Apophysitis of Distal Tibia

Radiography is the initial and most appropriate imaging modality for evaluating both pes cavus and apophysitis of the distal tibia, with specific findings that help establish these diagnoses. 1

Pes Cavus Radiographic Findings

Weight-bearing Radiographs

• Anteroposterior (AP) View:

  • Increased talo-first metatarsal angle (typically >0°, with studies showing mean values of 1.9° ± 7.9° in affected patients) 2
  • Less talar head coverage/decreased talonavicular angle (mean -4.2° ± 9.7° compared to -11° ± 8° in normal feet) 2
  • Adduction of the forefoot
  • Narrowing of the forefoot width

• Lateral View:

  • Increased height of the medial longitudinal arch
  • Increased calcaneal pitch angle
  • Plantarflexed first metatarsal
  • Dorsiflexed talus
  • Vertical positioning of the calcaneus

Additional Views

• Oblique Views: Helpful to assess for underlying causes such as tarsal coalition 1
• Standing Full-length Lower Extremity Views: Important to evaluate overall alignment and biomechanical impact

Apophysitis of Distal Tibia Radiographic Findings

Standard Radiographs

• AP and Lateral Views:
  • Widening of the distal tibial physis/growth plate
  • Irregular ossification of the distal tibial apophysis
  • Soft tissue swelling adjacent to the distal tibia
  • Periosteal reaction along the distal tibia
  • Normal alignment of the ankle joint (to differentiate from fractures)

Special Considerations

• Comparison with the contralateral side is essential to identify subtle asymmetries
• Weight-bearing views are preferred to assess functional alignment 1
• Fluoroscopically positioned images may provide improved visualization of subtle findings 1

Clinical Relevance and Diagnostic Pitfalls

Pes Cavus

• Pes cavus is not a diagnosis but a manifestation of multiple underlying conditions 3
• Approximately 66% of cavovarus feet result from subtle neurological diseases that may only become evident later in life 3
• Cavovarus should never be considered physiological; a neurological condition should always be excluded 3
• Tarsal coalition (both calcaneonavicular and subtalar) can present with cavovarus deformity rather than the more commonly associated flatfoot 4

Apophysitis

• Can mimic stress fractures or infection
• May be difficult to differentiate from normal growth plate variations in adolescents
• Serial radiographs may be necessary to monitor progression or resolution

When to Consider Advanced Imaging

While radiography is the initial imaging modality, consider advanced imaging in these scenarios:

• CT: When suspecting tarsal coalition as the underlying cause of pes cavus 1
• MRI: When neurological causes of pes cavus are suspected (e.g., Charcot-Marie-Tooth disease) 5
• Ultrasound: For soft tissue evaluation around the distal tibia in apophysitis 1

Diagnostic Algorithm

1. Obtain weight-bearing AP, lateral, and oblique radiographs of the foot for pes cavus
2. Obtain AP and lateral views of the ankle for distal tibial apophysitis
3. Compare with contralateral side when possible
4. If radiographs are inconclusive but clinical suspicion remains high:
   • For pes cavus: Proceed to CT for bony architecture or MRI for neurological causes
   • For apophysitis: Consider MRI to evaluate for bone marrow edema and soft tissue inflammation

Remember that pes cavus can be an early manifestation of underlying neurological disorders, so thorough evaluation beyond radiographic findings is essential for proper management and prognosis 5.