Eccentric training of the gastrocnemius-soleus complex in chronic Achilles tendinopathy results in decreased tendon volume and intratendinous signal as evaluated by MRI.

Background: Satisfactory treatment results have been reported after eccentric calf muscle strength training in patients with chronic Achilles tendinopathy.

Hypothesis: Magnetic resonance imaging may be a useful adjunct in the evaluation of the effect of 3 months of eccentric calf muscle strength training.

Study Design: Prospective cohort study.

Methods: Using magnetic resonance imaging, the Achilles tendons were investigated in 25 patients (16 men and 9 women) ranging in age from 28 to 70 years (median, 51 years) before and after training. Five different magnetic resonance imaging sequences were used. Tendon volume and mean intratendinous signal were calculated using a new seed-growing technique showing 99.3% and 96.6% intraobserver reliability, respectively. The clinical outcome was categorized according to pain level and performance using a questionnaire completed by the patient.

Results: The eccentric training resulted in a 14% (mean) decrease of tendon volume measured on T1-weighted images, from 6.6 +/- 3.1 cm3 to 5.8 +/- 2.3 cm3 (P < .05). The intratendinous signal in the symptomatic Achilles tendon measured on proton density-weighted images decreased 23% (mean), from 227 +/- 77 signal units to 170 +/- 83 signal units (P < .05). The gadolinium contrast agent-enhanced images did not add further value compared with other sequences.

Clinical Outcome: The clinical outcome was categorized as excellent in 10, good in 3, fair in 5, and poor in 8 patients. The Delta signal correlated significantly with the pain level (P < .05).

Conclusions: Eccentric training resulted in decreased tendon volume and intratendinous signal and was correlated with an improved clinical outcome. Magnetic resonance imaging techniques can be used as an adjunct to clinical evaluation by monitoring morphologic effects in clinical treatment studies of Achilles tendinopathy.