The Black Bone Disease: Is There A Gender Difference In Prevalence Of Ochronotic Arthropathy? An Epidemiological Overview.

Alkaptonuria (AKU) is a rare inherited metabolic disease associated with various clinical and radiological abnormalities due to homogentisic acid deposition. Ochronotic arthropathy is the musculoskeletal manifestation that occurs in patients with AKU, and it is often an occasional finding during joint replacement surgery. Since AKU is known to have an autosomal recessive transmission, its prevalence should not show any gender discrepancy. Despite this, the authors’ clinical experience suggested a marked prevalence in the male sex, with patients undergoing hip and knee joint replacements: we investigated the current literature to observe whether our case series was an exception. A systematic review was performed on PubMed, Scopus, and Embase with different combinations of the keywords “ochronosis”, “alkaptonuria”, “prosthesis”, “total joint replacement”. Search yielded 157 studies, on which we performed a primary evaluation. As there are no specific orthopaedic registries for this condition, we collected the sex prevalence of ochronosis from case reports and case series in the literature. Overall, from the studies suitable for inquiry, we collected a total of 195 patients with ochronotic arthropathy who underwent joint replacement surgery. Of these, 124 were males and 67 females. We speculate that due to environmental factors, such as work or sports activity, chondral cloth damage causes elevated formation of chondral debris, triggering the apoptotic process, known to be ochronotic arthropathy damaging process: Environmental factors should, in our opinion, explain the gender difference observed.