A small study conducted in Japan, published in CardioVascular and Interventional Radiology in July 2014, demonstrates that transcatheter arterial embolization is feasible and that it rapidly relieves pain associated with knee osteoarthritis and restores knee function.
The researchers reported in the paper that mild to moderate knee osteoarthritis that is resistant to treatment by nonsurgical options and that is not severe enough to warrant joint replacement “represents a challenge in its management”. They hypothesized that abnormal neovessels and accompanying nerves are possible sources of pain and that transcatheter arterial embolization can relieve pain associated with knee osteoarthritis by selectively occluding these abnormal neovessels, thus reducing pain and restoring knee function.
Yuji Okuno, Department of Orthopedic Surgery, Edogawa Hospital, and colleagues, carried out the prospective study between June 2012 and December 2013 in Edogawa Hospital, Tokyo, Japan. The 14 patients (eight female; mean age, 65.2±8.3 years; range 49–76 years) who were enrolled received explanations about various management modalities and the potential risks, benefits, and outcomes of transcatheter arterial embolization as an alternative treatment for osteoarthritis-related knee pain. The patients then provided written informed consent to the procedure.
The investigators included patients who had moderate to severe medial knee pain (visual analog scale [VAS] >50mm) resistant to at least three months of conservative therapies (anti-inflammatory drugs, physical therapy, muscle strengthening, and intra-articular injection of hyaluronic acid). All patients were assessed by routine radiographs, and those with severe osteoarthritis changes (Kellgren–Lawrence grade three or higher) were excluded because they were candidates for total knee arthroplasty. They excluded patients on the basis of local infection, malignancy, advanced atherosclerosis, rheumatoid arthritis, and prior knee surgery.
Amine Korchi, Department of Diagnostic and Interventional Radiology, Geneva University Hospitals, Switzerland, a member of the research team, told Interventional News: “Endovascular embolization of the musculoskeletal system is somehow limited compared to other fields of interventional radiology, and is mainly performed for bleeding in the context of trauma or after joint arthroplasty, for soft tissue vascular malformations and for pre-operative devascularisation of tumours.
This study unveils a new and unconventional endovascular approach to treat resistant pain from knee osteoarthritis in a minimally invasive fashion.
The results of this study at one year are encouraging, and this novel interventional radiology procedure seems promising. However, further larger and high quality trials are warranted to validate our findings and to depict the efficacy, safety and complication profiles of this procedure on a larger scale.
Moreover, many interesting areas of research could arise from our study, such as the potential role of angio-MRI in the detection of abnormal neovessels and thus in the selection of candidates for embolization, and also its role in the evaluation of outcomes. It could be also interesting to study the effect of embolic agent’s size and type on clinical outcomes and occurrence of complications such as non-target embolization.
Osteoarthritis is a common and major cause of pain and disability, and it is very exciting to see interventional radiologists stepping into this field, thinking outside the box and advancing research and knowledge.”
The researchers used imipenem/cilastatin sodium (in 11 patients) or 75µm calibrated Embozene microspheres (in three patients) as embolic agents. Imipenem/cilastatin sodium is approved as an antibiotic, is slightly soluble in water, and, when suspended in contrast agent, forms 10–70µm particles that exert an embolic effect, the researchers wrote. The embolic effect of Imipenem/cilastatin sodium is temporary and the inflammatory reaction is unknown. The mean volumes used in the study was a 2.5 mL/5mL suspension. The particle size of Embozene was calibrated at 75µm, its embolic effect is longer-term and inflammatory reaction low. The mean volume used in the study was 0.068 mL/2 mL particle volume. The investigators then assessed adverse events and changes in Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores.
Okuno and colleagues identified abnormal neovessels within soft tissue surrounding knee joint using arteriography. There were no major adverse events related to the procedures and transcatheter arterial embolization rapidly improved WOMAC pain scores from 12.2±1.9 to 3.3±2.1 at one month after the procedure, with further improvement seen at four months (1.7±2.2). WOMAC total scores changed from 47.3±5.8 to 11.6±5.4 at one month, and dropped further to 6.3±6 at four months. These improvements were maintained in most cases at the final follow-up examination at a mean of 12±5 months (range 4–19 months).