What is the appropriate initial management for a partial Achilles tendon tear?

Initial Management of Partial Achilles Tendon Tear

For partial Achilles tendon tears, initial conservative management with immobilization and functional rehabilitation is appropriate for most patients, but surgical excision of degenerated tissue should be strongly considered for significant partial ruptures (approaching or exceeding 50% of tendon width) due to poor response to conservative measures and risk of progression to complete rupture. 1, 2

Immediate Assessment and Diagnosis

• Confirm the diagnosis using at least two clinical tests: Thompson/Simonds squeeze test, decreased ankle plantar flexion strength, palpable gap in the tendon, and increased passive ankle dorsiflexion (Matles test) 3
• Obtain MRI or ultrasound imaging to determine the extent of the tear (percentage of tendon width involved), as this is critical for treatment decisions 4, 5
• Document the exact location of the tear within the tendon, as anatomic structure influences rupture patterns 5

Treatment Algorithm Based on Tear Severity

For Tears <50% of Tendon Width

Initial conservative management is reasonable but requires close monitoring:

• Immobilize in a protective boot or cast that limits dorsiflexion to 0 degrees for 2-4 weeks 3
• Begin early protected weight bearing within 2 weeks 3
• Progress to full weight bearing in a protective boot with controlled ankle mobilization by 2-4 weeks 3
• Implement progressive rehabilitation including exercise, tendon loading, electrical stimulation, and photobiomodulation 4

Critical caveat: Recent finite element modeling demonstrates that partial ruptures can progress to complete ruptures during functional rehabilitation even when affecting less than 50% of tendon width, regardless of material properties or subtendon twisting 1. This challenges the traditional "50% rule" and necessitates vigilant monitoring during conservative treatment.

For Tears ≥50% of Tendon Width or Significant Partial Ruptures

Surgical treatment should be strongly considered as the primary option:

• Significant partial ruptures respond poorly to conservative measures and do not improve with time 2
• Surgical excision of degenerated tissue leads to complete pain relief and full restoration of function with long-standing effects in most cases 2
• Limited open repair demonstrates significantly fewer wound infections compared to standard open repair 3

Conservative Management Protocol (When Selected)

If conservative treatment is chosen, implement the following structured approach:

• Weeks 0-2: Immobilization in protective device limiting dorsiflexion, early protected weight bearing 3
• Weeks 2-4: Full weight bearing in protective boot, controlled ankle mobilization with free plantar flexion 3
• Weeks 4-12: Progressive rehabilitation with tendon loading exercises, strength training, and modalities 4
• Serial imaging: Repeat ultrasound or MRI at 4-6 weeks to assess for progression to complete rupture 1

When to Abandon Conservative Treatment

Surgical intervention becomes necessary if:

• Persistent pain beyond 6-8 weeks of conservative treatment 2
• Evidence of tear progression on follow-up imaging 1
• Failure to achieve functional milestones (normal gait by 6-8 weeks) 6
• Palpable gap increases or new symptoms develop 5

Patient Selection Considerations

Favor surgical treatment for:

• Young, active patients desiring return to sports 3
• Patients with high functional demands 3
• Competitive athletes requiring swift return to activity 7
• Tears approaching or exceeding 50% width 2

Conservative treatment is preferred for:

• Elderly or low-demand patients 3
• Patients with significant comorbidities 3
• Those unable to comply with surgical rehabilitation 3
• Very small tears (<30% width) in non-athletes 5

Return to Activity Timeline

• Conservative treatment: Return to pre-injury activity levels typically requires 6 months 4
• Surgical treatment: Return to sports between 3-6 months, with low-impact activities beginning around 10-12 weeks 3
• Full sports participation generally safe at 4-6 months depending on sport demands and functional testing 3

Common Pitfalls to Avoid

• Do not rely solely on the "50% rule" for treatment decisions, as smaller tears can progress to complete ruptures during rehabilitation 1
• Avoid corticosteroid injections in or near the Achilles tendon, as these are not recommended and may increase rupture risk 8
• Do not delay surgical referral for persistent pain beyond 6-8 weeks, as chronic partial ruptures lead to hypoxic tissue states and immature, painful scars 2
• Ensure patient compliance with protective devices and weight-bearing restrictions, as rerupture risk remains significant 3, 6