FRI0596 Feasibility of joint structural analysis in hemochromatosis hand arthropathy using high-resolution peripheral quantitative computed tomography – first results and clinical correlations. (12th June 2018)

• Record Type: Journal Article
• Authors: Heilmeier, U.R.; Burghard, A.J.; Kapoor, P.; Voll, R.E.; Finzel, S.
• Is Part Of: Annals of the rheumatic diseases. Volume 77(2018)Supplement 2
• Page Start: 821
• Page End: 822
• Publication Date: 2018-06-12
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2018-eular.4903
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Hereditary Hemochromatosis (HH) is a common inherited disorder and characterised by an excess iron accumulation in several organs with consecutive organ dysfunction. 1 Apart from the liver, the joints are a major site of excess iron deposition. Joint pain counts among the most frequent (>50%), earliest, and most debilitating symptoms of HH. 2 To date, joint health status in HH patients is routinely assessed on hand radiographs. 3 However, plain radiography is a low-resolution, 2D-technique with limited sensitivity to detect early joint changes or to monitor subtle progression of joint damage. 4 With the advent of high-resolution peripheral quantitative computed tomography (HR-pQCT), a promising imaging tool has emerged allowing for in vivo 3D characterisation of human joint microstructure at a spatial resolution of 130 µm. 5 Due to its high sensitivity to detect and monitor subtle, short-term joint changes, HR-pQCT has been successfully applied to patients with RA. 6 However, to date, HR-pQCT has not been used to characterise joint and bone changes seen in HH arthropathy. Objectives: Here, we aimed to investigate in a cohort of HH patients 1) if the usage of HR-pQCT is feasible on HH patients; 2) to quantify joint microstructure of metacarpophalangeal joints (MCP2–4) in this specific patient group; and 3) investigate the relationship between HR-pQCT-derived joint microstructural parameters and clinical outcomes. Methods: 25 HH patients were enrolled and their HH history and treatment were recorded. MCP joints of all patients were imaged at a clinical HR-pQCT system (XtremeCT, Scanco Medical AG). 330 images were acquired covering MCP 2, 3 and 4. The joint space (JS) morphology of each MCP was quantified from the HR-pQCT images semi-automatically 4 and volume (JSV), joint space width mean (JSW), JSW variance (JSW.SD), and JSW asymmetry (JSW.AS) were calculated. Results: Out of the 75 MCP joints available for analysis, 79% were successfully segmentable, and 19% required semi-manual intervention to separate the individual bones. 3 joints were excluded due to motion artefacts, and 1 joint was unsegmentable. HH patients were 32–72 years old, in 64% male, and had been diagnosed with HH 2 months to 40 years ago. 15% were pain free at the study date. HH patients with pain showed significantly lower JSV at MCP 2 and 4 (p=0.009) and exhibited a significantly higher joint asymmetry in MCP 3 (p=0.012) compared to their pain free colleagues. When looking at clinical correlations we found that time since HH diagnosis was positively correlated with the MCP4 JSW asymmetry (R 2 =0.451, p=0.040) and MCP 4 JSW.SD (R 2 =0.475, p=0.030). The number of phlebotomies since diagnosis was strongly correlated with the JSW.SD (MCP2–4: 0.4552<0.581, p<0.050) at all MCP sites. Conclusions: Our study provides the first evidence that joint space assessment of MCPs via HR-pQCT in patients with hereditary hemochromatosis is feasible and can provide a thorough structural joint characterisation and thus support the physician in his initial HH arthropathy assessment. Our findings suggest, that regular phlebotomies since diagnosis may preserve joint space morphology leading to a more evenly maintained joint space. However, larger studies are needed to validate our results. Disclosure of Interest: None declared