Mark Little (Royal Berkshire NHS Foundation Trust, Reading, UK) described the emergence of, and advancement within, musculoskeletal (MSK) embolotherapy as “fast-paced” during his presentation on the trends and developments in the field, delivered at this year’s European Conference on Embolotherapy (22–25 June, Nice, France). Featuring in the meeting’s Joints session, the presentation’s take-home message was that the “signs are encouraging” when it comes to MSK embolotherapy’s integration into more mainstream practice.
Among the opening statements from Little was the “[importance of discussing] agents”—“different territories need different embolic agents,” he informed delegates. For osteoarthritis of the hand or tendinopathy in the foot, “you would not want a permanent embolic”, which is where the “antiquated” antibiotic imipenem, in combination with cilastatin, comes in. It acts as a temporary embolic agent, Little explained, and it has “rapidly emerging potential.”
For example, for plantar fasciitis, which is “really difficult to treat” and “extremely painful”, imipenem/cilastatin (I/C) can be injected into the posterior tibial artery, resulting in reduced pain and plantar fascia thickness. Sports medicine, Little went on, is “a real growth area” for MSK embolotherapy, as hyperaemia that cannot be treated conservatively may be resolved with agents such as I/C. However, a current limitation, Little acknowledged is the fact that I/C is not approved for embolotherapy in many countries, and the UK and USA are not among those where approval is granted.
Nevertheless, Little conveyed the significance of the fact that MSK embolotherapy has the potential to treat “a breadth of conditions,” listing tennis elbow, for which surgical options are limited, and adhesive capsulitis, which is increasingly prevalent as a result of the increasing prevalence of diabetes.
Little then turned to his area of specialism—genicular artery embolization (GAE)—which has the “largest evidence base to date” of all MSK embolotherapies. “We have done a lot of work looking at GAE and how we can refine the treatment,” he supplemented.
By way of example, Little referred to imaging from one of his own cases—medial compartment knee osteoarthritis, which “[showed] a large area of abnormal synovitis.” The approach for this patient was to cannulate the superior medial genicular artery, Little detailed, but, crucially, “to maintain the normal in-flow vessel.”
This is “very different” to the endpoint for prostate arterial embolization—”we are not wanting to completely block the in-flow vessel”, the result of which could be necrosis. Instead, Little “[prunes] the area of abnormality while maintaining normal osseus blood flow.”
To further illustrate the potential of MSK embolotherapy, Little referenced a small study of I/C to treat chronic lower back pain that had not been responsive to conservative therapy. However, given the size of the cohort, “we still have a lot more work to do”, he admitted.
Moving on the address the scientific rationale for MSK embolotherapy, Little described how the conditions are “underpinned by [an] area of hyperaemia.” New abnormal blood vessel formation “results in the release of cytokines” followed by “[hypersensitisation] of the nerves” and “pain”.
Next on the agenda for Little was to outline how “new” pain as a symptom to treat actually is within interventional radiology (IR)—typically, the means of assessing pain-related outcomes of treatment has been limited to the visual analogue scale. But, “what if your pain goes from a 10 to a 5?” Little asked rhetorically, “what does that mean in patients’ daily lives?” This is where minimally clinical important difference as a measure of pain outcome has a role to play—except that what that looks like for GAE is, “right now, anybody’s best guess.” Hence, this should be an area of focus in the field, Little advised. An “interesting area of future research” will be “the interplay between the brain and the knee”, as “how patients view pain impacts their progress,” Little then asserted.
The presenter summarised the scope for MSK embolotherapy’s more widespread use as “encouraging”. Recent National Institute for Health and Care Excellence (NICE) guidelines want evidence for its effectiveness, Little shared, in the form of “randomised controlled trials [RCTs] against sham procedure or best current practice,” with more patient-reported outcomes. GENESIS 2—an RCT against sham procedure—is, therefore, a study to watch. Little sees longer-term data and multicentre studies following on from this.
Fielding questions from the audience following the presentation, Little responded to an enquiry into whether use of antibiotics as temporary embolic agents could lead to patients developing resistance. “A good question—I have no idea”, Little admitted, going on to say “one would intuitively think, yes.” He then acknowledged that the main issue with antibiotics for this indication is the “East/West divide”—“we [in the UK] are very much limited”, as a result of the temporary agent I/C’s lack of availability.
A follow-up question on his preferred embolic material saw Little state that the MSK community is “crying out for imipenem” and all of its “mystical, magical properties” when it comes to treating hands and feet. For knees, he continued, “there is good data for permanent embolics”.