Musculoskeletal disease burden of hereditary hemochromatosis

Metabolic and endocrine diseases, cartilage calcification and arthritis

PURPOSE OF REVIEW

Osteoarthritis is the most common form of rheumatologic disease, with numerous factors increasing the risk of developing the condition; calcification of cartilage is common place in osteoarthritis. Regardless of these risk factors, certain disorders predispose individuals to developing arthritis. Pathologic mechanisms in cartilage calcification and advances in their understanding are reviewed alongside metabolic and endocrine arthritis.

RECENT FINDINGS

There is growing evidence suggesting that changes in chondrocytes and the extracellular environment both contribute to the calcification. Further evidence suggests that signaling cascades that are involved in physiological mineralisation are involved in the pathological process(es); data in mouse models continue to add weight to these hypotheses and correlate with human osteoarthritis data. Recent study of rare forms of arthritis is adding useful information that may help understand joint diseases in the general population and how therapies may be targeted.

SUMMARY

There is little doubt that calcium-containing crystals are involved in the osteoarthritis process contributing both biomechanically and biochemically. Understanding the processes involved provides important therapeutic opportunities. Furthermore, important information is often discovered in studying rare conditions in which these pathologies are inevitable.

Arthritis mimicking sports-related injuries

Arthritis, including inflammatory, crystal deposition, and synovial proliferative disorders, may mimic sports injury. The purpose of this article is to review the clinical and radiologic findings of arthropathies that can present in athletes and be confused with internal derangement.

Increased risk of arthropathies and joint replacement surgery in patients with genetic hemochromatosis: a study of 3,531 patients and their 11,794 first-degree relatives

OBJECTIVE

Genetic hemochromatosis (GH) is an autosomal recessive disease in individuals of Northern and Western European descent. Heterozygosity for the C282Y mutation is common (6-20%). Arthropathy is one of the few complications of GH suggested not to be associated with iron body stores; synovial iron deposition remains in iron-depleted patients. Previous studies suggest an elevated prevalence of clinical and radiographic signs of arthropathy in patients with GH, and 2 smaller studies suggest a possibly elevated risk of joint replacement surgery, but more mixed results are shown regarding risks with HFE genotype. We therefore assessed the risks of arthropathy and joint replacement surgery in patients with GH and in their first-degree relatives (FDRs).

METHODS

We performed a population-based cohort study of 3,531 patients with GH and of their 11,794 FDRs (assumed to be heterozygous for the C282Y mutation) using nationwide Swedish population-based health and census registers. Hazard ratios (HRs) of arthropathies and joint replacement surgeries among patients and their FDRs (versus the general population) were assessed using Cox regression.

RESULTS

Between 1997 and 2005, 406 of 3,531 patients were reported/hospitalized with any noninfectious arthropathies, including osteoarthritis, corresponding to an HR of 2.38 (95% confidence interval [95% CI] 2.14-2.64). Patients were also at increased risk of hip replacement (HR 2.77, 95% CI 2.27-3.38) and knee replacement (HR 2.14, 95% CI 1.58-2.88) surgery. Among the 11,794 FDRs (patients excluded), we found no increased risk of any of the joint morbidities.

CONCLUSION

Patients with GH, but not their FDRs, are at increased risk of arthropathies, including the need for joint replacement surgery.

[Inflammatory diseases with liver and joint involvement. A differential diagnostic challenge]

Elevated levels of liver enzymes in patients with rheumatic symptoms require a comprehensive differential diagnostic thought process. On the one hand there can be hepatic involvement of primarily rheumatological diseases but this is quite rare. Drug-induced liver injury by antirheumatic medication is more frequent. On the other hand arthralgia can be a sign of primary hepatopathy whereby hemochromatosis and autoimmune hepatitis (AIH) are typical examples. Furthermore, some liver diseases are associated with rheumatological diseases, such as primary biliary cirrhosis (PBC) and chronic hepatitis C infection (HCV). Only an exact diagnosis will lead to specific treatment which will improve the symptoms and course of disease.

Erosive and inflammatory joint changes in hereditary hemochromatosis arthropathy detected by low-field magnetic resonance imaging

The aim of the article is to describe and characterize the hemochromatosis arthropathy of the hand by low-field MRI in symptomatic and asymptomatic patients. Forty-nine patients with hereditary hemochromatosis (37 with and twelve without arthropathy) were examined clinically and by low-field MRI of the hands. The examination showed heterogeneous degenerative and inflammatory joint changes such as erosions (in 84% of all symptomatic patients), synovitis (77%), bone marrow edema (38%), subchondral cysts (30%), tenosynovitis (30%), joint space narrowing (73%) and osteophytes (59%) including hook-shaped osteophytes at MCP joints (32%). Mild joint changes were also seen in a lower percentage of asymptomatic patients. This is the first larger study addressing the joint changes of the hand in hereditary hemochromatosis using low-field MRI. Our study emphasizes the inflammatory and destructive character of the arthropathy besides the well-known degenerative joint changes described in conventional X-ray. The impact of joint changes in asymptomatic patients deserves further investigation.

Arthritis Pathology

The pathologic examination of failed joints, whether natural or artificial, is an indispensable part of the understanding of arthritis, as it is the last, and still best opportunity to determine or verify the correct diagnosis. Accuracy in pathologic diagnosis, based on a firm understanding of the various disease processes, provides reliable data for use in clinical registries, provides an opportunity to explain the "unusual" clinical presentation, and ultimately gives the "best evidence" for basing further treatments and prognosis for the individual patient.

Rheumatologic manifestations of benign and malignant haematological disorders

Diseases of blood and lymphoreticular system can have multisystem manifestations. Rheumatologic involvement has been reported in association with many benign and malignant haematological disorders; these patients are equally likely to present to both clinical rheumatologists and haematologists. This review focuses on the well-described rheumatologic features, other occasionally reported rheumatologic manifestations and unusual musculoskeletal complications related to the treatment in patients with underlying haematological conditions. The aim of this review is to help increase the awareness of rheumatologic manifestations seen in the blood disorders and to highlight the potential diagnostic pitfalls.

Pathophysiology of articular chondrocalcinosis--role of ANKH

Calcium pyrophosphate (CPP) crystal deposition (CPPD) is associated with ageing and osteoarthritis, and with uncommon disorders such as hyperparathyroidism, hypomagnesemia, hemochromatosis and hypophosphatasia. Elevated levels of synovial fluid pyrophosphate promote CPP crystal formation. This extracellular pyrophosphate originates either from the breakdown of nucleotide triphosphates by plasma-cell membrane glycoprotein 1 (PC-1) or from pyrophosphate transport by the transmembrane protein progressive ankylosis protein homolog (ANK). Although the etiology of apparent sporadic CPPD is not well-established, mutations in the ANK human gene (ANKH) have been shown to cause familial CPPD. In this Review, the key regulators of pyrophosphate metabolism and factors that lead to high extracellular pyrophosphate levels are described. Particular emphasis is placed on the mechanisms by which mutations in ANKH cause CPPD and the clinical phenotype of these mutations is discussed. Cartilage factors predisposing to CPPD and CPP-crystal-induced inflammation and current treatment options for the management of CPPD are also described.