Magnetic resonance signal, rather than tendon volume, correlates to pain and functional impairment in chronic Achilles tendinopathy

PURPOSE: To depict abnormal tendon matrix composition using magnetic resonance imaging (MRI) in chronic Achilles tendinopathy, and correlate intratendinous signal alterations to pain and functional impairment. MATERIAL AND METHODS: MRI of the Achilles tendon was performed on 25 patients with chronic Achilles tendinopathy (median age 50, range 37-71 years). All patients suffered from pain in the mid-portion of the Achilles tendon. Intratendinous signal was calculated from five different sagittal sequences, using a computerized 3D seed-growing technique. Pain and functional impairment were evaluated using a questionnaire completed by patients. RESULTS: Severity of pain and functional impairment correlated to increased mean intratendinous signal in the painful tendon in all MR sequences (P < 0.05, median r = 0.38, range 0.28-0.43 for pain; P < 0.05, median r = 0.48, range 0.29-0.49 for functional impairment). However, tendon volume did not correlate to pain or functional impairment (P > 0.05). Difference in mean intratendinous signal between symptomatic and contralateral asymptomatic tendons was highly significant in all sequences (P < 0.05) except on T2-weighted images (P = 0.6). CONCLUSION: Severity of pain and disability correlated to increased MR signal rather than to tendon volume in patients with unilateral mid-portion chronic Achilles tendinopathy.