Diagnostic Genicular Nerve Block Prior to Radiofrequency Ablation for Knee Osteoarthritis Pain
Condition: Osteoarthritis, Knee; Pain; Nerve; Lesion
MeSH terms: Osteoarthritis; Osteoarthritis, Knee
Study type: Interventional

Summary: 
      Chronic painful knee OA is a major cause of disability in older adults. In patients whose
      symptoms are refractory to conservative management but who do not wish to undergo TKA or,
      alternatively, are not operative candidates, genicular nerve RFA represents a promising
      treatment option.

      Investigators will determine if patients with chronic painful knee osteoarthritis experience
      meaningful and long-term improvement in pain, function, and analgesic use, as well as
      prevention of TKA after RFA of the genicular nerves. Investigators will also determine
      whether zero versus one set of diagnostic genicular nerve blocks

      Answering these questions will help determine if genicular nerve RFA is indeed a worthwhile
      treatment for chronic painful knee OA. Additionally, this will help determine the optimal
      diagnostic protocol for patient selection for this procedure, which has implications for
      improving treatment success rates, preventing unnecessary procedures, and decreasing
      healthcare cost savings.
    

Detailed description: 
      Knee osteoarthritis (OA) is one of the most common conditions and causes of disability in
      older adults, with an estimated prevalence of symptoms in 20-30% of individuals over 65 years
      of age. Pain associated with knee OA may have a central nervous system component, but
      intra-articular chemical pain mediators such as Substance P and Calcitonin-gene related
      peptide, possible intra-articular ischemic pain due to vasospasm, mechanical compression or
      irritation of the richly innervated subchondral bone, periosteum, synovium, and joint
      capsule, as well as peripheral genicular nerve sensitization have largely been implicated.

      Knee OA, in general, is treated conservatively with weight loss (when indicated), physical
      therapy, oral analgesic medications, and intra-articular corticosteroid or hyaluronic acid
      injections. If this approach fails to provide adequate pain relief and functional
      restoration, patients may be offered total knee arthroplasty (TKA), if they are surgical
      candidates. While, TKA is generally a safe procedure, like any major open surgery, it is
      associated with a risk of serious complications; a large cohort study of 83,756 patients
      demonstrated the annual incidence of venous thromboembolism (0.6%), myocardial infarction
      (0.5%), stroke (0.5%), and a 90 day mortality (0.7%) to all be significantly higher than the
      general population. Furthermore, some patients are not candidates for TKA due to
      co-morbidities such as morbid obesity or cardiopulmonary disease.

      Radiofrequency ablation (RFA) for knee joint denervation represents a promising intervention
      for patients with chronic painful knee osteoarthritis who have failed conservative management
      and are either not willing or not eligible for TKA. During RFA a thermal lesion is created by
      applying radiofrequency energy through an electrode placed at a target structure. RFA has
      been used to disrupt sensory afferent nociceptive nerve fibers supplying the zygapophyseal
      (facet) joints of the spine as well as the sacroiliac joint with excellent pain reduction and
      functional improvement when performed appropriately.

      To date, there are only two published studies that have investigated knee joint denervation
      by RFA for the treatment of chronic painful OA. In a randomized prospective study (n=35),
      Choi et al. found that genicular nerve RFA resulted in clinically meaningful pain improvement
      in approximately 60% of patients at 6 month follow-up. Improvement in function was also
      observed. Bellini and Barbieri report a series of 3 patients with chronic painful knee OA,
      two of whom who experienced meaningful pain and functional improvement after genicular nerve
      RFA.

      There is no evidence-based algorithm established which provides a means of properly selecting
      which patients would benefit from genicular nerve RFA. In the study performed by Choi et al.,
      only one set of diagnostic genicular nerve blocks with a threshold of 50% pain relief to be
      considered a "positive response" was used. In contrast, a well developed literature regarding
      selection of patients for medial branch RFA for facet-mediated pain indicates that two sets
      of diagnostic medial branch nerve blocks with a threshold of >80% pain reduction to be
      considered a "positive response" increased positive predictive value for both meaningful pain
      and functional outcomes to 80-90%. While the diagnosis of facet-mediated pain can be
      challenging given the variety of potential pain generators in the spine, diagnostic
      uncertainly is far less likely when evaluating the knee as a pain generator. In fact, it is
      unclear that any diagnostic blocks of the genicular nerves are needed given that this
      increase the potential for complications and healthcare costs compared to proceeding directly
      to the ablation procedure. It is vital that evidence-based selection criteria are developed
      for genicular nerve RFA in order to optimize clinical outcomes and minimize healthcare costs.
    

Intervention name(s): genicular nerve diagnostic block with lidocaine (local anesthetic); genicular nerve radiofrequency ablation
Intervention type(s): Procedure; Procedure
Intervention description(s): sensory denervation of the knee joint; Ablation of the genicular nerves of the knee by radiofrequency energy
Intervention MeSH terms: Lidocaine; Anesthetics, Local; Anesthetics
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Diagnostic