Spontaneous tendon ruptures in alkaptonuria

Abstract

chronosis, the musculoskeletal manifestation of alkaptonuria, is known to lead to degenerative changes of the spine and weight-bearing joints. Symptoms related to degeneration of tendons or ligaments with spontaneous ruptures have not previously been reported. Three patients are described with four spontaneous ruptures of either the patellar tendon or tendo Achillis as the first symptom of alkaptonuria. Alkaptonuria is a rare autosomal recessive metabolic disorder due to deficiency of the enzyme homogentisic acid oxidase which is involved in the metabolism of homogentisic acid, a metabolic product of the aromatic amino acids phenylalanine and tyrosine.1 The homogentisic acid which accumulates is polymerised to form a dark pigment which is deposited in connective tissues. The pigment is also selectively deposited in the hyaline cartilage of major peripheral joints and intervertebral discs leading to early degeneration and arthritis. Apart from pigmentation of the skin, sclera and the pinnae, systemic symptoms related to the genitourinary, cardiovascular and respiratory systems have also been described. 2 The musculoskeletal manifestation of alkaptonuria is called 'ochronosis', a term which was coined by Virchow because of the ochre or yellow appearance of the cartilage under the microscope. By the fourth or fifth decade the disease usually progresses from simple alkaptonuria to alkaptonuric arthropathy in approximately 30% of subjects. While degenerative changes of the spine and major joints have been frequently reported, [2][3][4] there is no report of spon-

Musculoskeletal manifestations of alkaptonuria: A case report and literature review

“…Tendons are also sites of ochronotic pigment deposition due to their high collagen content, leading to tendinopathy. Among those patients with ochronotic tendinopathy, the prevalence of spontaneous tendon or ligament ruptures is estimated to be approximately 20%–30% (16). The patellar and Achilles tendons are the most commonly affected, often involving the insertion sites of traction tendons, leading to enthesopathy.…”

“…The patellar and Achilles tendons are the most commonly affected, often involving the insertion sites of traction tendons, leading to enthesopathy. The deposition of pigmented HGA in collagenous tissues affects the structural integrity of collagen, increasing the risk of tendon rupture due to their high collagen content (16). An ultrasound examination of the Achilles tendon shows loss of fibrillary pattern, increased thickness, small focus of calcification, and increase in size of the retrocalcaneal bursa (5).…”

Alkaptonuria – a review of surgical and autopsy pathology

“…Histological examination of ligamentous tissue and tendons from around the knee joint showed finely granular, perinuclear pigmentation in fibroblasts. Spontaneous rupture of tendons is a rare complication of alkaptonuria 23 and appears to be the result of localized degeneration associated with intense pigment deposition. The factors governing this highly localized pigmentation are not known.…”

Neurological assessment and nerve conduction study findings in 22 patients with alkaptonuria from Jordan

“…10 Spontaneous tendon rupture has been also reported in AKU patients in two previous occasions and can be a presenting symptom of AKU. 11,12 Clinicians should therefore consider AKU diagnosis in young patients who have early degenerative changes in weight bearing areas.…”