Hemophilic arthropathy is a debilitating condition that can develop as a consequence of frequent joint bleeding despite adequate clotting factor replacement. The mechanisms leading to repeated spontaneous bleeding are unknown. We investigated synovial, vascular, stromal and cartilage changes in response to a single induced hemarthrosis in the FVIII-deficient mouse. We found soft tissue hyperproliferation with marked induction of neoangiogenesis and evolving abnormal vascular architecture. While soft tissue changes were rapidly reversible, abnormal vascularity persisted for months and, surprisingly, was also seen in uninjured joints. Vascular changes in FVIII-deficient mice involved pronounced remodeling with expression of α-Smooth Muscle Actin (SMA), Endoglin (CD105) and vascular endothelial growth factor, as well as alterations of joint perfusion as determined by in vivo imaging. Vascular architecture changes and pronounced expression of α-SMA appeared unique to hemophilia, as these were not found in joint tissue obtained from mouse models of rheumatoid arthritis (RA) and osteoarthritis (OA) and from patients with the same conditions. Evidence that vascular changes in hemophilia were significantly associated with bleeding and joint deterioration was obtained prospectively by dynamic in vivo imaging with musculoskeletal ultrasound and power Doppler of 156 joints (elbows, knees and ankles) in a cohort of 26 patients with hemophilia at baseline and during painful episodes. These observations support the hypothesis that vascular remodeling contributes significantly to bleed propagation and development of hemophilic arthropathy. Based on these findings, the development of molecular targets for angiogenesis inhibition may be considered in this disease.

Objectives Musculoskeletal ultrasound (US) is used increasingly to examine hemophilic arthropathy. However, quantitative algorithms to document findings are lacking. We developed and sought to validate a protocol quantifying hemophilic joint abnormalities. Methods Thirty‐one patients with hemophilia were examined serially for 2 years with musculoskeletal US (≈600 joint examinations and ≈6000 images). Based on the spectrum of pathologies, a quantitative algorithm, named Joint Tissue Activity and Damage Examination (JADE), was developed for soft tissue and osteochondral measurements, including power Doppler, using nominal group techniques. To study intra‐ and inter‐rater reliability, 8 musculoskeletal US–experienced hemophilia providers performed anatomic landmark recognition and tissue measurements on 86 images with arthropathic changes, with repetition 1 month later. Twenty‐three musculoskeletal US–inexperienced providers performed similar assessments. Inter‐operator reliability was established by 6 musculoskeletal US–experienced hemophilia providers, each acquiring images and JADE assessments of 3 hemophilic arthropathic joints. A radiologist and musculoskeletal sonographer functioned as adjudicators. The statistical analysis was performed with the intraclass correlation coefficient (ICC), Fleiss κ, and Cohen κ where appropriate. Results The musculoskeletal US–experienced providers showed excellent intra‐and inter‐rater reliability for tissue measurements (ICCs, 0.94–0.96). Agreement was good to excellent for landmark recognition (Fleiss κ, 0.87‐0.94). Inter‐operator reliability was excellent for measurements and landmark recognition (ICC, 0.90; Fleiss κ, 1.0). Agreement with adjudicators was mostly good to excellent. Musculoskeletal US–inexperienced providers showed excellent inter‐rater reliability for measurements (ICC, 0.96) and moderate agreement for landmark recognition (Fleiss κ, 0.58). Conclusions The JADE protocol appears feasible for quantifying hemophilic intra‐articular abnormalities. Musculoskeletal US–trained hemophilia providers showed high intra‐rater, inter‐rater, and inter‐operator reliability, supporting JADE as a protocol for clinical management and research.

Introduction Point-of-care (POC) musculoskeletal ultrasound (MSKUS) is increasingly used by hemophilia providers to guide management, however, pathologic tissue differentiation with US is uncertain. We sought to determine the extent to which POC MSKUS can identify and discriminate pathologic soft tissue changes in hemophilic arthropathy. Materials and Methods 36 adult patients with hemophilia A/B were prospectively enrolled. POC MSKUS was performed on arthropathic joints (16 knees, 10 ankles, and 10 elbows) using standard views by a MSKUS-trained and certified hematologist, who recorded abnormal intra-articular soft tissue accumulation. Within three days, magnetic resonance imaging (MRI) was performed using conventional and multi-echo ultrashort echo time (UTE) sequences. Soft tissue identification (synovial proliferation with or without hemosiderin, fat, and/or blood products) was performed by a musculoskeletal radiologist. Findings obtained with both imaging modalities were compared and correlated in a blinded fashion. Results There was perfect agreement between the modalities on the presence of abnormal soft tissue (34/36 cases). However, MSKUS was unable to discriminate between coagulated blood, synovium, intra- or extra-synovial fat tissue, or hemosiderin deposits due to wide variation in echogenicity. Conclusion MSKUS is valuable for POC imaging to determine the presence of soft tissue accumulation in discrete areas. However, due to limitations in MSKUS in discriminating the nature of pathological soft tissues and detecting hemosiderin, MRI will be required if such discrimination is clinically important.

Point-of-care ultrasound enabled intra-articular corticosteroid injections that provided highly effective, safe, and relatively long-lasting pain relief in haemophilic arthropathy. This approach should be used to improve pain management in haemophilic arthropathy.

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