ALKAPTONUREA PRESENTING AS SPONTANEOUS RUPTURE OF TENDOACHILLIS

INTRODUCTION: ‘Ochronosis’ literally meaning ‘ochre or yellow appearance’ (of the cartilage) was term used by Virchow to describe the musculoskeletal manifestation of alkaptonuria. Alkaptonuria is a rare autosomal recessive metabolic disorder. These patients have deficient homogentisic acid oxidase enzyme that is necessary for metabolism of homogentisic acid which in turn is produced from phenylalanine and tyrosine.[1] The homogentisic acid when in excess gets polymerized and accumulates into connective tissues leading to dark pigmentation of tissues. The pigment is also has affinity towards hyaline cartilage of major peripheral joints and intervertebral discs.[2] Its deposition leads to early degenerative changes and arthritis. Along with discoloration of the skin, sclera and the pinnae, it may have systemic involvement of the genitourinary, cardiovascular and respiratory systems.[3] Usually the disease progresses from simple alkaptonuria to alkaptonuric arthropathy by the fourth or fifth decade of life in 30% of patients.While degenerative changes of the spine and major joints have been frequently reported,[2-4] there are very few reports[5,6] of spontaneous rupture of tendons caused by the deposition of pigmentat the osseo-tendinous junction. We hereby report one such case where the patient presented with spontaneous rupture of tendon and on further investigations he was diagnosed as a case of alkaptonuria.