Achilles Tendinopathy: Why the Clinical Exam Still Matters in the Era of Ultrasound

What recent research reveals about palpation, tendon structure, and how clinicians should interpret imaging findings.

Introduction

Musculoskeletal ultrasound has become an essential tool in the evaluation of Achilles tendinopathy. High-resolution imaging allows clinicians to visualize tendon morphology in real time, identifying structural features such as tendon thickening, hypoechoic regions, and neovascularization.

Yet clinicians working in sports medicine frequently encounter a puzzling reality:

Two patients may demonstrate nearly identical ultrasound findings but report very different symptoms.

One tendon may appear structurally abnormal yet tolerate high levels of athletic loading. Another may appear relatively mild on imaging but remain extremely painful during activity.

This disconnect between structure and symptoms has been widely discussed in tendon research. A recent study published in the International Journal of Sports Physical Therapy offers additional insight into how clinical examination findings relate to tendon morphology in individuals with Achilles tendinopathy.

 Long-axis and Short-axis ultrasound of the Achilles tendon demonstrating normal fibrillar architecture.

What the Study Investigated

The study evaluated 182 individuals with midportion Achilles tendinopathy and compared several commonly used clinical pain measures with structural tendon characteristics observed on ultrasound.

Clinical assessments included:

• pain on palpation

• pain pressure threshold

• pain during hopping

• recalled pain levels

Ultrasound measurements included:

• tendon thickness

• tendon cross-sectional area

• degree of tendon thickening

The goal was to determine whether these clinical pain measures reflect underlying tendon morphology

The Key Finding

Among the clinical measures examined, pain on palpation was the only variable that demonstrated a relationship with tendon structure on ultrasound.

However, the strength of this relationship was modest, with correlation coefficients around r ≈ 0.20.

Statistically, this represents a weak correlation, meaning tendon structure explains only a small portion of symptom variability.

This finding reinforces a concept widely recognized in tendon research:

Structural abnormalities and symptoms are related, but they are not tightly coupled.

Pain in tendinopathy is influenced by multiple factors beyond morphology, including neural sensitivity, mechanical loading tolerance, and training history.

 Long-axis ultrasound of the Achilles tendon demonstrating normal fibrillar architecture.

Why Palpation May Reflect Tendon Behavior

Pain on palpation may capture something different from other pain measures evaluated in the study.

Unlike recalled pain or pressure threshold testing, palpation applies localized mechanical stress directly to the tendon.

In effect, the clinician is performing a targeted mechanical provocation test at the exact region where structural change may exist.

This may explain why palpation demonstrated a measurable relationship with tendon morphology while other pain measures did not.

In practical terms, palpation may provide insight into localized mechanical irritability of the tendon.

The Load Capacity Model of Tendinopathy

Modern tendon research increasingly describes tendinopathy as a problem of load tolerance rather than structure alone.

A tendon may appear abnormal on imaging yet tolerate high mechanical loads without symptoms.

Conversely, a tendon with relatively minor structural changes may become painful when mechanical load exceeds the tissue’s tolerance.

From this perspective:

• ultrasound reveals morphology

• clinical examination reveals mechanical irritability

Both dimensions contribute to understanding tendon behavior.

Ultrasound demonstrating tendon thickening and focal hypoechoic regions consistent with Achilles tendinopathy.

Understanding the Study Population

An important consideration when interpreting these findings is the age distribution of the study population.

Participants had a mean age of approximately 47 years (±13), meaning the majority fell between their mid-30s and early 60s.

In this age range, structural tendon remodeling is common. Tendon thickening and changes in collagen organization may reflect cumulative mechanical loading or age-related tissue adaptation.

This background variability in tendon structure may partially explain the modest correlations observed between symptoms and imaging findings.

Structural abnormalities observed on ultrasound may represent a mixture of:

• chronic loading adaptation

• biological remodeling

• degenerative change

rather than a single pathological process.

Implications for Sports Medicine Clinicians

For clinicians working with athletic populations, these findings should be interpreted within appropriate context.

Elite athletes frequently demonstrate structural tendon abnormalities on imaging despite having no symptoms or performance limitations.

Studies in elite runners and jumping athletes have shown that asymptomatic individuals often exhibit:

• tendon thickening

• focal hypoechoic regions

• Doppler vascularity

In these cases, imaging findings may reflect adaptation to repeated mechanical loading rather than symptomatic pathology.

Because the present study primarily examined a middle-aged population with chronic tendinopathy, its findings cannot be directly generalized to elite athletic populations.

This distinction highlights a critical principle in sports medicine imaging:

Structural abnormalities on ultrasound do not necessarily predict pain or performance capacity.

Anatomy of the Achilles tendon showing contributions from the gastrocnemius and soleus muscles.

The Role of Ultrasound in Tendon Evaluation

Despite the complex relationship between structure and symptoms, ultrasound remains an invaluable tool in the evaluation of tendon pathology.

Ultrasound allows clinicians to assess:

• tendon morphology

• focal degeneration

• partial tears

• neovascularization

• paratenon pathology

These findings can influence decisions regarding rehabilitation progression, load management, and return-to-sport planning.

However, imaging findings must always be interpreted alongside clinical examination and functional testing.

Clinical Takeaway

Advances in imaging technology have greatly improved our ability to visualize tendon structure.

Yet this study reminds us that simple clinical findings remain meaningful.

Ultrasound provides insight into the morphology of the tendon.

But clinical examination including palpation often reveals how the tendon behaves under mechanical stress.

Integrating imaging with clinical reasoning remains essential for accurate diagnosis and effective management of Achilles tendinopathy.

---

Training Offerings

References

1. O’Neill S, Watson PJ, Barry S. Don’t underestimate pain on palpation in the clinical exam for Achilles tendinopathy. Int J Sports Phys Ther. 2024.

2. Cook JL, Purdam CR. Is tendon pathology a continuum? Br J Sports Med. 2009.

3. Rio E, et al. Isometric exercise induces analgesia in patellar tendinopathy. Br J Sports Med. 2015.

4. Magnusson SP, Kjaer M. The impact of loading, unloading, ageing and injury on the human tendon. J Physiol. 2019.

5. Docking SI, Ooi CC, Connell D. Tendon structure changes after loading in athletes. Br J Sports Med. 2015.

6. Comin J, Cook JL, Malliaras P, et al. Sonographic abnormalities in asymptomatic athletes. Br J Sports Med. 2013.