What is the recommended approach for diagnosing Achilles tendinitis?

Diagnosing Achilles Tendinitis

The recommended approach for diagnosing Achilles tendinitis requires a detailed history and physical examination with at least two specific tests, including assessment for palpable gaps, decreased ankle plantar flexion strength, and pain reproduction with tendon loading. 1

Clinical History Assessment

• Obtain history of insidious onset with chronic posterior heel pain and swelling that is typically aggravated by increased activity and pressure from shoes 1
• Document pain that worsens with tendon-loading activities, which is characteristic of Achilles tendinopathy 2
• Note morning stiffness in the tendon area, which is one of the most useful diagnostic indicators 3
• Determine if pain is relieved when walking barefoot, which is common in insertional Achilles tendinitis 1

Physical Examination

• Perform at least two of the following tests to establish an accurate diagnosis: 1

  • Clinical Thompson test (Simonds squeeze test) - squeeze the calf muscle to assess for plantar flexion response
  • Assessment of decreased ankle plantar flexion strength
  • Palpation for a gap or defect in the tendon (loss of contour)
  • Evaluation of increased passive ankle dorsiflexion with gentle manipulation

• Examine for specific physical findings:

  • For insertional tendinitis, assess for prominence medially and laterally to the Achilles tendon insertion 1
  • Check for central or global tenderness at the tendon 1
  • Look for tendon thickening and palpable nodules, which are common in Achilles tendinopathy 1
  • Evaluate for anatomic deformities such as forefoot and heel varus, excessive pes planus, or foot pronation 1

Diagnostic Imaging

• Plain radiographs may be useful to identify:

  • Spurring or erosion at the Achilles tendon insertion in insertional tendinitis 1
  • Calcific tendinosis or soft-tissue swelling 1
  • Other bony abnormalities that may cause symptoms 1

• Advanced imaging should be reserved for: 1

  • Cases where diagnosis remains unclear after thorough history and physical examination
  • Recalcitrant pain despite adequate conservative management
  • Preoperative evaluation

• When advanced imaging is needed:

  • Ultrasonography can demonstrate tendon thickening, decreased echogenicity, and calcification 1, 3
  • MRI is sensitive (95%) and specific (95%) for detecting chronic degenerative changes, partial tears, and tendon thickening 1, 4

Important Diagnostic Considerations

• Distinguish between insertional (at calcaneal attachment) and non-insertional (midportion) Achilles tendinitis, as they have distinct features and therapeutic approaches 2
• Consider differential diagnoses including retrocalcaneal bursitis, Haglund's deformity, Achilles tendon rupture, and neurologic causes of heel pain 1
• Be aware that excessive swelling and pain can limit examination in acute cases, potentially masking the diagnosis 5
• Note that inflammation may be present in early phases, but chronic cases typically show degenerative changes rather than active inflammation 3

Diagnostic Algorithm

1. Begin with patient self-reports of morning stiffness and/or pain in the tendon area 3
2. Perform physical examination with at least two specific tests (Thompson test, strength assessment, gap palpation, dorsiflexion assessment) 1
3. If diagnosis is clear based on clinical findings, no imaging is initially required 1
4. For unclear cases or treatment-resistant cases, proceed with plain radiographs first 1
5. If further clarification is needed, ultrasound or MRI may be indicated 1, 4

Remember that Achilles tendinopathy is largely a clinical diagnosis, and imaging should be used as a supplementary tool rather than the primary diagnostic method 2.