Thompson Test For Achilles Tendon Rupture: Purpose, Test Details & Results

Purpose of Thompson Test For Achilles Tendon Rupture

Diagnosing an Achilles tendon rupture quickly and accurately is crucial for optimal recovery. The Thompson test, also known as the Simmonds-Thompson test, stands as the gold standard clinical tool for detecting these injuries. It's favored worldwide by orthopedic and emergency clinicians because it's fast, non-invasive, and highly reliable for identifying complete ruptures.

Below, you'll find a summary of the core reasons clinicians use the Thompson test, followed by an in-depth exploration of its clinical importance.

Why the Thompson Test Matters

The Achilles tendon is the strongest and largest tendon in the human body. Its rupture, however, can be surprisingly easy to miss—especially in the acute phase. Early and accurate detection is essential for timely surgical or conservative management, which in turn affects patient outcomes, recovery time, and risk of long-term disability 1 2 4.

The Thompson test answers a fundamental clinical question: Is the Achilles tendon still intact and functional? When performed correctly, it helps clinicians distinguish between partial tears (which may still allow some function) and complete ruptures (which typically result in significant dysfunction) 2 3 6.

The Global Standard for Achilles Rupture Diagnosis

• The Simmonds-Thompson test has served as the reference standard for decades 6.
• It's widely taught and used in trauma, orthopedic, and sports medicine settings.
• A positive test (no plantarflexion with calf squeeze) almost always means a complete rupture 2 3 6.
• Variants, like the ultrasound-enhanced RAUT test, build upon the Thompson test’s foundation to improve diagnostic confidence, especially for less experienced clinicians 1.

When the Test Is Most Useful

• Acute injuries: Early diagnosis prevents chronic problems and complications 1 4.
• Ambiguous cases: When symptoms or signs are unclear, the test can provide rapid clarity 2.
• Resource-limited settings: Requires no special equipment, making it accessible and cost-effective 2 6.

Thompson Test For Achilles Tendon Rupture Details

The Thompson test is simple to perform but powerful in its implications. Understanding its mechanics, variations, and limitations helps clinicians avoid diagnostic pitfalls and improves patient care.

How the Thompson Test Is Performed

1. Patient Positioning: The patient lies prone (face down) with feet hanging off the edge of the examination table. This relaxes the calf muscles and Achilles tendon 3 6.
2. Calf Squeeze: The examiner squeezes the mid-portion of the calf muscle (gastrocnemius and soleus complex) 3 6.
3. Observe the Foot:
   • Normal (Negative Test): The foot plantarflexes (points downward) in response to the squeeze, indicating an intact tendon connection 2 3 6.
   • Abnormal (Positive Test): The foot fails to move (no plantarflexion), strongly suggesting a complete rupture 2 3 6.

Why the Test Works

• The Achilles tendon connects the calf muscles to the heel bone. Squeezing the calf should pull on the tendon, causing the foot to point down.
• If this connection is lost (complete rupture), the force is not transmitted, so the foot remains still 3.

Variations and Adjuncts

Simmonds-Thompson Test

• Often called interchangeably with the Thompson test, it emphasizes the same maneuver and is widely recognized as the clinical gold standard 3 6.

Realtime Achilles Ultrasound Thompson (RAUT) Test

• Combines ultrasound imaging with the Thompson maneuver to visualize tendon movement in real time.
• RAUT offers improved sensitivity and specificity, especially for novice examiners and in ambiguous cases 1.
• Useful as a cost-effective adjunct, requiring minimal additional training for clinicians 1.

O’Brien Needle Test

• Involves inserting a needle into the tendon and observing movement during calf squeeze.
• Used when the Thompson test is inconclusive, especially in cases involving the distal 10 cm of the tendon 5.

Limitations and Pitfalls

• Partial Ruptures: The test is reliable for complete ruptures but may not detect partial tears, as some plantarflexion may still occur 2.
• Active Plantarflexion: The ability to actively plantarflex does not rule out a rupture, as accessory muscles and tendons can compensate 4.
• Anatomical Variability: Rare anatomical variations or previous injuries can lead to false negatives or ambiguous results 3 5.
• Intraoperative Use: The test may have limited value during surgery, as demonstrated in cadaveric studies 2.

Clinical Pearls

• Always compare with the uninjured side for reference.
• Absence of plantarflexion strongly suggests a complete rupture, but clinical context and adjunct tests (like RAUT or needle test) may be needed for ambiguous presentations 1 2 5.

Thompson Test For Achilles Tendon Rupture Results & Follow-Up

Interpreting the Thompson test result is pivotal for guiding further management, from imaging to treatment planning. Here’s how clinicians make sense of the findings and what happens next.

What a Positive Thompson Test Means

• High Specificity: A positive test (no plantarflexion) is highly specific for complete rupture. Immediate diagnosis enables early intervention, which is essential for optimal recovery 2 3 6.
• Immediate Actions: Confirm clinical findings, discuss treatment options (surgical vs. conservative), and plan for immobilization or surgery 2 3.

When the Test Is Negative

• Intact Tendon or Partial Tear: Plantarflexion with calf squeeze generally means the tendon is not fully ruptured, but partial tears can still be present 2 3.
• Further Evaluation: If suspicion remains high (due to swelling, bruising, or difficulty walking), adjunctive imaging like ultrasound or MRI may be warranted 1 5.

Handling Inconclusive or Atypical Results

• Adjunctive Tests: The RAUT test (ultrasound-guided Thompson) can clarify uncertain cases, especially for less experienced examiners 1.
• Needle Test: Especially valuable for assessing the integrity of the distal tendon in ambiguous situations 5.
• Comparative Testing: Always compare both sides for subtle differences.

Follow-Up and Patient Management

• Confirmed Rupture: Discuss treatment pathways, expected recovery timelines, and rehabilitation protocols.
• Partial Tear or Unclear Findings: Arrange for imaging, specialist referral, or close follow-up as needed.
• Patient Education: Explain the importance of early diagnosis, adherence to treatment, and the risks of delayed care.

Evidence and Reliability

• Sensitivity & Specificity: Studies consistently demonstrate high sensitivity and specificity for the Thompson test in diagnosing complete Achilles ruptures 1 2 6.
• Reliability Across Clinicians: Even novice reviewers achieve high diagnostic accuracy, especially when using the RAUT technique 1.
• Limitations: Remember, the test is less useful intraoperatively or for detecting partial tears 2.

Conclusion

The Thompson test remains an indispensable tool for the diagnosis of Achilles tendon ruptures, balancing simplicity with clinical accuracy. Here’s what clinicians and patients should remember:

• Rapid, Accurate Diagnosis: The Thompson (Simmonds-Thompson) test is the worldwide clinical standard for identifying complete Achilles tendon ruptures 2 3 6.
• Simple to Perform: Requires no special equipment and can be done quickly at the bedside 3 6.
• High Sensitivity and Specificity: Particularly effective for complete tears, with adjuncts like RAUT and the needle test available for ambiguous cases 1 2 5.
• Limitations Acknowledged: Less reliable for partial ruptures or intraoperative assessment; clinical context and imaging may be required 2 5.
• Guides Immediate Management: Results inform treatment decisions, follow-up imaging, and patient counseling.

Key Points:

• The Thompson test is the reference clinical exam for Achilles ruptures.
• A positive test (no plantarflexion) almost always means complete rupture.
• Partial tears and atypical presentations may need further investigation.
• Adjunct tools like ultrasound (RAUT) increase diagnostic confidence.
• Early diagnosis and management are essential for optimal recovery.

By mastering the Thompson test and its nuances, clinicians ensure prompt, evidence-based care for patients with suspected Achilles tendon injuries.