Extensive Atraumatic Heterotopic Ossification of the Achilles Tendon in an Adolescent with Metabolic Syndrome: A Case Report

Disturbed glycolipid metabolism activates CXCL13-CXCR5 axis in senescent TSCs to promote heterotopic ossification

Heterotopic ossification (HO) occurs as a common complication after injury, while its risk factor and mechanism remain unclear, which restricts the development of pharmacological treatment. Clinical research suggests that diabetes mellitus (DM) patients are prone to developing HO in the tendon, but solid evidence and mechanical research are still needed. Here, we combined the clinical samples and the DM mice model to identify that disordered glycolipid metabolism aggravates the senescence of tendon-derived stem cells (TSCs) and promotes osteogenic differentiation. Then, combining the RNA-seq results of the aging tendon, we detected the abnormally activated autocrine CXCL13-CXCR5 axis in TSCs cultured in a high fat, high glucose (HFHG) environment and also in the aged tendon. Genetic inhibition of CXCL13 successfully alleviated HO formation in DM mice, providing a potential therapeutic target for suppressing HO formation in DM patients after trauma or surgery.

Acute fracture of an extensively ossified segment of the Achilles tendon

Extensive tendon ossification is thought to be rare and is hypothesised to occur due to cell-mediated tissue remodelling. Literature outlining risk factors for the development of an ossified segment, and then a consequent fracture is limited to case reports and case series. A woman in her fifties with a background of several autoimmune disorders presented to a sports and exercise medicine clinic with posterior ankle pain following a bout of brisk walking a month prior. CT and MRI imaging demonstrated a fractured extensively ossified segment of the corresponding Achilles tendon. Conservative treatment was trialled for six months, however, was unsuccessful. Surgical excision of the calcified fragment and flexor hallucis longus tendon transfer were suggested as a potential solution. This case is compared with and builds on current literature surrounding pathophysiology and optimal treatment of extensively ossified segments of the Achilles tendon.