Baseline functional status impacts patient-perceived resolution following rehabilitation for Achilles tendinopathy

Exercise-based physical therapy is effective for managing Achilles tendinopathy. Despite these successes, up to 45% of patients do not respond to therapy. The mechanisms differentiating patients who improve and those who do not remain unclear, although differences in pre-rehabilitation pain, tendon structure and function might explain this individual variability. The aim was to explore differences in pain, structure, and functional changes between patients with and without meaningful self-perceived resolution following a 12-week eccentric rehabilitation protocol for Achilles tendinopathy. Thirty-seven patients with chronic midportion Achilles tendinopathy (28 M/9F; 46 ± 12 years) followed a 12-week eccentric rehabilitation protocol. Functional and structural measurements and questionnaires were assessed pre- and post-intervention to evaluate pain, tendon structure, and function. A blinded medical doctor classified treatment response based on patient-perceived resolution, grouping participants into those with meaningful improvement (N = 28) and those without (N = 9). Patients without meaningful improvement had significantly higher VISA-A scores, greater free Achilles tendon stiffness, and higher pain-onset hopping repetitions (all p < 0.05) pre-intervention compared to those who reported meaningful improvement. After 12 weeks of rehabilitation, VISA-A and pain-onset hopping repetitions showed significant effects for time (p = 0.010; p = 0.024), group (p = 0.022; p = 0.003), and interaction (p = 0.032; p = 0.002). Tendon stiffness, maximal voluntary contraction, and palpation pain changed significantly over time (p = 0.009; p = 0.016; p = 0.044, respectively). Achilles tendon loading during dynamic exercises showed no between-group differences (all p > 0.05). Higher baseline functioning was linked to reduced improvement following rehabilitation, indicating that baseline functional status may influence treatment outcomes. Recognizing such baseline differences could help predict patient-perceived resolution and guide individualized interventions.