Calcium Pyrophosphate Dihydrate Deposition Disease in Young Patients: Two Case Reports

Joint manifestations revealing inborn metabolic diseases in adults: a narrative review

Inborn metabolic diseases (IMD) are rare conditions that can be diagnosed during adulthood. Patients with IMD may have joint symptoms and the challenge is to establish an early diagnosis in order to institute appropriate treatment and prevent irreversible damage. This review describes the joint manifestations of IMD that may be encountered in adults. The clinical settings considered were arthralgia and joint stiffness as well as arthritis. Unspecific arthralgias are often the first symptoms of hereditary hemochromatosis, chronic low back pain may reveal an intervertebral disc calcification in relation with alkaptonuria, and progressive joint stiffness may correspond to a mucopolysaccharidosis or mucolipidosis. Gaucher disease is initially revealed by painful acute attacks mimicking joint pain described as "bone crises". Some IMD may induce microcrystalline arthropathy. Beyond classical gout, there are also gouts in connection with purine metabolism disorders known as "enzymopathic gouts". Pyrophosphate arthropathy can also be part of the clinical spectrum of Gitelman syndrome or hypophosphatasia. Oxalate crystals arthritis can reveal a primary hyperoxaluria. Destructive arthritis may be indicative of Wilson's disease. Non-destructive arthritis may be seen in mevalonate kinase deficiency and familial hypercholesterolemia.

20 Years of Radiographic Imaging: Crystalline Deposits Causing Severe Arthropathy and Erosions

Urate crystal gout arthritis and calcium pyrophosphate deposition disease (CPPD) are crystalline arthropathies seen in middle age to elderly patients, but are also seen in the active duty military population. Flares of either can be identified by acute joint pain, associated swelling, tenderness, and warmth. Definitive diagnosis involves synovial analysis from arthrocentesis. Gout and CPPD are common inflammatory joint diseases. Both arthropathies presenting themselves in the same joint are rather rare. An elderly female with a history of gout presented to the hospital with severe hip pain. She was on urate-lowering therapy at the time, and uric acid levels on admission were not significantly elevated. Radiographic imaging of her hip demonstrated periarticular cartilage calcifications. A review of radiographic imaging over the last 20 years found significant erosive arthropathy in multiple joints and radiographic evidence of chondrocalcinosis, suggesting CPPD. Synovial analysis was not obtained during this admission as the patient declined procedures due to her elderly age. Her condition improved with oral steroids. Few literatures have demonstrated that gout and CPPD are common crystal arthropathies that can occur concomitantly in the same joint. A 20-year review of imaging in an elderly female with known gout arthropathy found that she had radiographic evidence of concomitant CPPD-associated damage to many of her joints. Clinicians should be aware of the different erosive arthropathies, their corresponding imaging findings, evaluation for underlying metabolic disorders if appropriate, and the possibility that they may occur in the same joint. Early prevention can reduce joint destruction later in life.

3D assessment of intervertebral disc degeneration in zebrafish identifies changes in bone density that prime disc disease

Back pain is a common condition with a high social impact and represents a global health burden. Intervertebral disc disease (IVDD) is one of the major causes of back pain; no therapeutics are currently available to reverse this disease. The impact of bone mineral density (BMD) on IVDD has been controversial, with some studies suggesting osteoporosis as causative for IVDD and others suggesting it as protective for IVDD. Functional studies to evaluate the influence of genetic components of BMD in IVDD could highlight opportunities for drug development and repurposing. By taking a holistic 3D approach, we established an aging zebrafish model for spontaneous IVDD. Increased BMD in aging, detected by automated computational analysis, is caused by bone deformities at the endplates. However, aged zebrafish spines showed changes in bone morphology, microstructure, mineral heterogeneity, and increased fragility that resembled osteoporosis. Elements of the discs recapitulated IVDD symptoms found in humans: the intervertebral ligament (equivalent to the annulus fibrosus) showed disorganized collagen fibers and herniation, while the disc center (nucleus pulposus equivalent) showed dehydration and cellular abnormalities. We manipulated BMD in young zebrafish by mutating sp7 and cathepsin K, leading to low and high BMD, respectively. Remarkably, we detected IVDD in both groups, demonstrating that low BMD does not protect against IVDD, and we found a strong correlation between high BMD and IVDD. Deep learning was applied to high-resolution synchrotron µCT image data to analyze osteocyte 3D lacunar distribution and morphology, revealing a role of sp7 in controlling the osteocyte lacunar 3D profile. Our findings suggest potential avenues through which bone quality can be targeted to identify beneficial therapeutics for IVDD.