Spontaneous Achilles tendon rupture as the initial presentation of ochronosis: a case report.

INTRODUCTION

Alkaptonuria (AKU) is a rare autosomal recessive metabolic disorder characterized by homogentisic acid accumulation leading to ochronosis, which weakens connective tissues and may rarely affect tendons.

PRESENTATION OF CASE: A 43-year-old man presented with sudden right ankle pain and functional loss without preceding trauma. Examination revealed a palpable gap and pigmentation of the sclera and ear. Intraoperatively, the Achilles tendon was friable and black. Histopathology confirmed ochronotic degeneration. Surgical repair using a modified Krackow suture with intraosseous anchoring achieved stable fixation and uneventful recovery.

DISCUSSION: This case illustrates spontaneous Achilles tendon rupture as an initial manifestation of AKU. Oxidative stress-induced collagen degeneration leads to tendon fragility. Recognition of characteristic pigmentation and histological features is essential for diagnosis.

CONCLUSION

Ochronosis should be considered in unexplained tendon ruptures. Surgical repair and metabolic management, including nitisinone, can optimize outcomes.