Don't Underestimate Pain on Palpation in the Clinical Exam for Achilles Tendinopathy

Midportion Achilles tendinopathy is a common injury affecting individuals across various activity levels, characterized by pain, impaired performance, and pathological changes in tendon structure. Although the clinical examination is crucial for diagnosis and management, the relationship between pain measures and tendon pathology remains unclear, prompting further investigation into their diagnostic and prognostic value.

This study aimed to (1) investigate the relationship between diverse clinical pain measures - pain on palpation, recall pain, pain pressure threshold (PPT), and pain during hopping - and pathological tendon structure in individuals with midportion Achilles tendinopathy, and (2) determine whether these pain measures represent overlapping or distinct features of the pain experience.

Cross-Sectional Study.

One hundred and eighty-two participants with midportion Achilles tendinopathy completed clinical assessments for Achilles tendon pain (pain on palpation, recall pain, PPT, pain with hopping), and ultrasound imaging for Achilles tendon structure (thickness, degree of thickening, and cross-sectional area [CSA]) at a single visit. Spearman correlations were used to analyze the relationships between pain measures and Achilles tendon structure. Linear regression controlling for PPT was used to assess the relationship between pain on palpation and Achilles tendon structure.

All pain measures were significantly related (|r| = .19 - .51, all p<0.018). Pain on palpation was the only pain measure significantly related to Achilles tendon structure (thickness: r =.20, p=0.007; CSA: r =.21, p=0.005). Pain on palpation remained a significant predictor of tendon thickness (b=0.03, p=0.002), CSA (b=0.04, p=0.003), and degree of thickening (b=0.02, p=0.028) in linear regression models.

Pain on palpation is a simple and important clinical measure that captures a unique aspect of the pain experience and relates to pathological Achilles tendon structural changes. This makes pain on palpation an important measure for the diagnosis and prognosis in those with midportion Achilles tendinopathy.

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