Undiagnosed Ochronosis Presented as Severe Osteoarthritis With Concomitant Osteoporotic Fracture

Introduction: Ochronosis is a rare autosomal recessive disorder of tyrosine metabolism, leading to deposition of elevated levels of homogentisic acid in different parts of the body, especially in fibrous and cartilaginous tissues. The current study presents a case with delayed diagnosis and osteoporotic fracture in addition to severe osteoarthritis and calcification. Case Presentation: A 56-year-old female with low back pain and painful knees and hips referred to the center. Right hip arthroplasty was performed to manage her severe osteoarthritis. Although characteristic features of ochronosis such as urine darkening, subcutaneous pigmentation and degenerative ochronotic arthropathy resembling osteoarthritis were observed in this patient, surprisingly it remained unrecognized until the 5 decade. Bone mineral density showed that osteoporosis and zoledronic acid had