Recent studies have identified immune-component cells in biopsy specimens from patients with non-ruptured chronic Achilles tendinopathy. This study was designed to better understand the inflammatory component of this disorder.

Subjects were 17 patients with chronic Achilles tendinopathy, presenting for high-volume injections (HVI), and 19 patients with Achilles tendon rupture, presenting for surgical repair. Biopsies from each group were compared with those of hamstring tendons collected from patients undergoing anterior cruciate ligament reconstruction. The biopsies were studied for inflammatory signatures.

Immunohistochemistry of the biopsies of the Achilles groups demonstrated an increased expression of CD14＋and CD68＋ cells compared to the healthy hamstring tendons (P＝0.0015 and P＝0.0007 respectively). There was no significant difference between the two Achilles groups in the number of these cells found. Compared with the controls, the Achilles groups demonstrated a complex activation protein signature, and expressed markers of interferon and glucocorticoid receptor macrophage activation pathways. Using CD30 1 as a marker of vascularization, increased expression was found in tendinopathy (P＝0.002) and ruptured Achilles tissue (P＝0.0002).

This study of patients with Achilles tendinopathy, including those with ruptures, demonstrates evidence of chronic inflammation.