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.