CUHK pioneers HR-pQCT-based study to track bone erosion in rheumatoid arthritis Helps distinguish harmless microchanges from true joint damage and promotes repair through early, effective treatment
CU Medicine has pioneered the use of HR-pQCT to track bone erosion in rheumatoid arthritis (RA). This technology distinguishes harmless small erosions from inflammatory damage, while detecting microchanges associated with RA. By enabling early and accurate diagnosis, HR-pQCT facilitates timely “treat-to-target” therapy, and can even reverse bone erosions in early-stage patients.
(From left) Dr Isaac Cheng Tsz-ho, Postdoctoral Fellow; Professor Tam Lai-shan, Chair Professor and Head of Division of Rheumatology;and Dr So Ho, Associate Professor (Clinical), all from the Division of Rheumatology in the Department of Medicine and Therapeutics at CU Medicine
The Chinese University of Hong Kong (CUHK)’s Faculty of Medicine (CU Medicine) has pioneered the use of 3D high-resolution peripheral quantitative computed tomography (HR-pQCT) to track bone erosion in rheumatoid arthritis (RA). A landmark eight-year follow-up study reveals that HR-pQCT can accurately distinguish harmless, non-inflammatory, physiological small erosions from true RA joint damage. Crucially, the study shows that early personalised “treat-to-target” (T2T) therapy can stabilise and even reverse large bone erosions in early-stage patients. The team is now exploring integrating this technology into early RA screening to achieve “early detection and early treatment”. The findings have been published in the international journal, Annals of the Rheumatic Diseases.
The first two years after RA onset represent a “golden window” for treatment
RA is a chronic autoimmune disease that affects over 70 million people worldwide, with around 30,000 patients in Hong Kong alone. In RA, the immune system mistakenly attacks the synovial membrane of the joints, causing inflammation and structural damage. The first two years after symptom onset are considered a critical window for treatment. Without timely intervention, joints may gradually become deformed and lose mobility, leading to irreversible damage and reducing quality of life.
Bone erosion is a hallmark of RA, particularly prevalent in hand metacarpophalangeal (MCP) joints, and serves as a critical marker of disease severity and a predictor of irreversible disability. However, conventional imaging modalities, including X-ray, CT scans and MRI scans, have limited sensitivity for detecting early or subtle structural damages, hindering timely and precise diagnosis.
The research team from the Division of Rheumatology at CU Medicine was the first to use 3D HR-pQCT to assess bone erosion in 247 RA patients over an eight-year follow-up period. Among the participants, 149 attended general rheumatology clinics and received usual care, while the remaining 98 were newly diagnosed patients with symptom durations of less than two years who followed a strict T2T algorithm for the first year after diagnosis before transitioning to usual care. The T2T approach involves selecting personalised treatment plans according to disease activity and treatment targets.
HR-pQCT distinguishes harmless small erosions from inflammatory damage
The team first performed baseline imaging scans in RA patients to assess peripheral bone erosion at the second metacarpal head, a standard site near the index finger’s MCP joint for evaluating hand arthritis, bone erosion and microstructural changes, and compared the results with those from 78 healthy controls. The results showed that 29% of RA patients had small erosions (less than 1 mm³), compared with 26% of healthy controls; the distribution of these small erosions did not differ significantly between the two groups. In contrast, a much larger difference was observed for larger erosions (greater than 5 mm³): 17% of RA patients had large bone erosions, compared with only 3% of healthy controls.
| Healthy Controls (78 persons) | RA patients (247 persons) | |
|---|---|---|
| Small erosion (<1mm³) | 26% | 29% |
| Large erosion (>5mm³) | 3% | 17% |
Dr Isaac Cheng Tsz-ho, co-first author of the study and Postdoctoral Fellow in the Department of Medicine and Therapeutics at CU Medicine, said: “Small erosions were equally prevalent in RA patients and healthy controls, with minimal volumetric differences, indicating a lack of disease-specific discriminatory value. During the subsequent eight years, small erosions in RA patients demonstrated remarkable stability, with no significant changes observed even under effective T2T suppression, suggesting that these small erosions may reflect physiological or biomechanical variants rather than an inflammatory process.”
Dr Cheng explains that conventional X-ray scans have limited sensitivity in detecting early or small bone erosions, making it difficult to accurately assess the joint structure of patients in early stages. In contrast, HR-pQCT can detect microchanges, allowing clinicians to rule out non-inflammatory bone erosion with greater accuracy.
Dr So states that while RA cannot be fully cured, it can be effectively managed through treat-to-target therapy to control inflammation, slow joint damage progression, and preserve joint function and quality of life. This underscores the critical importance of early diagnosis and intervention.
Early diagnosis and treatment promote large erosion regression
In the follow-up study, the team found that among RA patients with large erosions, more than half (53%) showed regression of bone erosion. Further analysis indicated that these patients typically had a shorter disease duration and received T2T therapy, which led to better disease control. This finding reinforces the importance of early referral, early treatment and tight disease control. Among RA patients with small bone erosions, 14% showed improvement, while the majority (64%) remained stable.
Dr So Ho, Associate Professor (Clinical) of the Division of Rheumatology in the Department of Medicine and Therapeutics at CU Medicine stated: “The findings of this study demonstrate that high-resolution 3D imaging enables precise measurement of the size and distribution of bone erosions. Not all bone or joint abnormalities are indicative of RA, and this approach can help avoid misdiagnosis arising from over-interpretation in clinical practice. At the same time, it allows for the early and accurate diagnosis of true RA cases, thereby achieving the goal of early detection and treatment.”
Professor Tam Lai-shan, corresponding author of the study, and Chair Professor and Head of Division of Rheumatology, Department of Medicine and Therapeutics, CU Medicine, said: “Patients with RA who receive treatment early during the two-year golden window can effectively protect their joints and reduce long-term, irreversible damage. Anyone experiencing persistent joint swelling, morning stiffness, or hand pain should seek medical evaluation as soon as possible. Looking ahead, our team plans to integrate HR-pQCT into research frameworks for early RA assessment, with the goal of developing an imaging-based risk stratification model to identify patients at high risk of progressive joint damage. We also aim to explore whether HR-pQCT can be used to detect preclinical or very early-stage RA in selected high-risk individuals.”
Professor Tam states that the team is now exploring the integration of HR-pQCT into early RA screening, and collecting more clinical data, with the aim of establishing this technology as a routine diagnostic tool for RA.
Ms Lau (left), now in her 70s, first developed joint pain, swelling in her middle and index fingers, and morning stiffness 10 years ago. After consulting a family doctor, she was referred to a rheumatologist within a few months and was diagnosed with RA, for which she began treat-to-target therapy. Within six months of treatment, her inflammation was brought under control, and her finger joint mobility is now comparable to that of anyone her age.
