Long-Term Outcomes of the Knee and Hip Arthroplasties in Patients with Alkaptonuria

Arthroscopic ankle arthrodesis in two alkaptonuria patients

Alkaptonuria is a very rare disorder in which homogentisic acid accumulates due to a deficiency in the activity of homogentisic acid 1,2 dioxygenase. This deficiency results in deposition of a yellowish-brown pigment in connective tissue. Such deposition is termed 'ochronosis' and leads to deterioration in the formation and structure of proteoglycans in hyaline cartilage. These actions lead to fragmentation and rapid destructive arthritis. Often, ochronotic arthritis appears at 40-60 years of age, and many patients are treated symptomatically. Here, we report two patients (three ankles) with ochronotic arthritis who were treated with ankle arthrodesis. In all cases, the postoperative clinical score improved, but the time needed for fusion was prolonged and symptomatic subtalar arthropathy developed in the early postoperative period.

Bilateral Patellar Tendon Rupture Following Total Knee Arthroplasty in a Patient With Alkaptonuria: A Case Report

Alkaptonuria (AKU) is a rare hereditary disorder of tyrosine degradation. The disorder is characterized by the accumulation of a pigment called homogentisic acid. Its accumulation can lead to the breakdown of connective tissue, including tendons. This report presents a 46-year-old male with a history of bilateral total knee arthroplasty (TKA) who sustained bilateral patellar tendon rupture after an acute injury. A single-stage bilateral knee revision with direct repair of the extensor mechanism augmented with Achilles allograft was performed. The procedure was successful, and the patient had an excellent post-operative outcome at one year post-operatively. This case attempts to highlight the possible complications from AKU in order to better counsel patients with this condition who are undergoing TKA.

Case report: Thoracolumbar spinal stenosis associated with alkaptonuria

Background

Alkaptonuria is a rare autosomal genetic disorder with an incidence of about 1 in 1 million per year. Spinal involvement often manifests in the later stages of the disease. However, this is the first report of the presentation of thoracolumbar spinal stenosis.

Case presentation

We report the case of a 61-year-old female patient with significant thoracolumbar stenosis symptoms. The patient had obvious kyphosis with preoperative lower extremity muscle strength grade 2/5. Symptoms and imaging signs initially suggested ankylosing spondylitis. This patient was classified into motor incomplete injury (ASIA C). However, the patient was found to have melanin deposits on the sclera and skin, and the urine was darkened at rest. CT and MRI both suggested no bone bridge connection between vertebrae, which was the key difference between ankylosing spondylitis and alkaptonuria in imaging. Most importantly, urine specimen testing and intraoperative pathology demonstrated alkaptonuria. The patient underwent spinal decompression and vertebral body fixation. Postoperative recovery was good: the patient had significantly relieved pain and could stand and walk.

Conclusion

This case is the first report of thoracolumbar spinal stenosis associated with alkaptonuria involving the spine.

Reverse Total Shoulder Arthroplasty in Alkaptonuric Shoulder: Case Presentation, Review of Literature, and Technical Considerations

Importance

Alkaptonuric shoulder arthropathy is a challenging clinical entity in arthroplasty. In this report, we describe an atypical presentation, technical considerations, a literature review, and some recommendations of significant benefits to shoulder surgeons.

Objective

The author's objective in this report is to illustrate the deleterious metabolic effects of ochronosis on cartilage and the development of early arthritis.

Design

This is a case report study, done in May 2021.

Setting

Middle East, Jordan.

Introduction

Alkaptonuria is a metabolic disease of amino acid metabolism that can affect multiple organ systems, including the musculoskeletal system. The musculoskeletal system manifestations usually involve the spine, knee, and, uncommonly, the shoulder. Tissue ochronosis caused by alkaptonuria can cause significant damage to the joint and surrounding soft tissue envelope. In this case, we presented a patient who has end-stage glenohumeral arthritis and rotator cuff arthropathy secondary to ochronosis.

Case Presentation

In this case report, we present a 42-year-old male patient who presented to the clinic with severe right shoulder pain and limitations of the range of motion, especially with abduction. The patient underwent radiographic assessment, which showed a rotator cuff arthropathy combined with advanced degenerative changes of the right glenohumeral joint. The patient underwent reverse total shoulder arthroplasty. After the surgery and on follow-up later on for a period of one year and after a period of physiotherapy and rehabilitation, the patient showed remarkable improvement in the pain and range of motion.

Conclusion

Alkaptonuria can have a detrimental effect on the articular cartilage and the surrounding soft tissue envelope, which might manifest clinically as early degenerative arthritis changes in a young adult patient. Shoulder involvement is extremely rare and can manifest with substantial injury to the glenohumeral joint; whenever such extensive damage is present, shoulder arthroplasty is the best treatment.

Structure-Function Relationship of Homogentisate 1,2-dioxygenase: Understanding the Genotype-Phenotype Correlations in the Rare Genetic Disease Alkaptonuria

Alkaptonuria (AKU), a rare genetic disorder, is characterized by the accumulation of homogentisic acid (HGA) in organs, which occurs because the homogentisate 1,2-dioxygenase (HGD) enzyme is not functional due to gene variants. Over time, HGA oxidation and accumulation cause the formation of the ochronotic pigment, a deposit that provokes tissue degeneration and organ malfunction. Here, we report a comprehensive review of the variants so far reported, the structural studies on the molecular consequences of protein stability and interaction, and molecular simulations for pharmacological chaperones as protein rescuers. Moreover, evidence accumulated so far in alkaptonuria research will be re-proposed as the bases for a precision medicine approach in a rare disease.

Untargeted NMR Metabolomics Reveals Alternative Biomarkers and Pathways in Alkaptonuria

Alkaptonuria (AKU) is an ultra-rare metabolic disease caused by the accumulation of homogentisic acid (HGA), an intermediate product of phenylalanine and tyrosine degradation. AKU patients carry variants within the gene coding for homogentisate-1,2-dioxygenase (HGD), which are responsible for reducing the enzyme catalytic activity and the consequent accumulation of HGA and formation of a dark pigment called the ochronotic pigment. In individuals with alkaptonuria, ochronotic pigmentation of connective tissues occurs, leading to inflammation, degeneration, and eventually osteoarthritis. The molecular mechanisms underlying the multisystemic development of the disease severity are still not fully understood and are mostly limited to the metabolic pathway segment involving HGA. In this view, untargeted metabolomics of biofluids in metabolic diseases allows the direct investigation of molecular species involved in pathways alterations and their interplay. Here, we present the untargeted metabolomics study of AKU through the nuclear magnetic resonance of urine from a cohort of Italian patients; the study aims to unravel molecular species and mechanisms underlying the AKU metabolic disorder. Dysregulation of metabolic pathways other than the HGD route and new potential biomarkers beyond homogentisate are suggested, contributing to a more comprehensive molecular signature definition for AKU and the development of future adjuvant treatment.

Ipsilateral hip and knee joints ochronotic arthropathy treated by total joint replacement, a case report

Background

Ochronotic arthropathy affecting the hip and knee joints is one of the musculoskeletal manifestations of alkaptonuria which results from a tyrosine amino acid metabolism disorder. The condition has no definitive management; however, end-stage joint arthritis is well treated by total joint replacement.

Case presentation

We present a case of a healthy male patient who presented with left hip and bilateral knee (more on the left side) progressive pain and limitation of motion how was diagnosed as having advanced arthritis and was treated by total hip and total knee replacement for the left hip and knee joints respectively. Intraoperatively, the tissues had blackish discoloration characterizing ochronosis. This patient was diagnosed as having ochronotic arthropathy based on the intraoperative findings.

Conclusions

Accurate diagnosis of ochronotic arthropathy could only be reached intraoperatively; furthermore, end-stage joint arthritis could be treated efficiently by total joint replacement surgery.