For patients with osteoarthritis of the knee, a
minimally invasive procedure called cooled radiofrequency ablation
(CRFA) provides better pain reduction and functional improvement
compared to steroid injection of the knee, concludes a study in Regional Anesthesia & Pain Medicine, published by Wolters Kluwer.
"This study demonstrates that CRFA is an effective long-term
therapeutic option for managing pain, and improving physical function
and quality of life, for patients suffering from painful knee
osteoarthritis when compared with intra-articular steroid injection,"
according to the clinical trial report by Leonardo Kapural, MD, PhD, of
the Center for Clinical Research, Winston-Salem, N.C., and colleagues.
Most Patients Get Lasting Relief of Knee Osteoarthritis Pain with CRFA
Knee osteoarthritis is a common and painful condition in older
adults. Knee replacement surgery is an established option for patients
with advanced osteoarthritis, but is not appropriate for all patients
because of age or health status. Even patients who have knee replacement
may have ongoing pain, despite a mechanically satisfactory prosthesis.
Intra-articular (within the joint) steroid injection is commonly
performed, but provides only short-term pain relief. In addition,
steroids may have adverse effects on cartilage over time
Dr. Kapural and colleagues evaluated CRFA as an alternative to
steroid injection in 151 patients with chronic pain from knee
osteoarthritis. The patients had had knee pain for an average of about
ten years, with many previous treatments. They were randomly assigned to
undergo CRFA or steroid injection.
The noninvasive CRFA procedure uses radiofrequency energy to
interrupt pain transmission by a specific nerve (genicular nerve) of the
knee. Before the procedure, a local anesthetic nerve block is performed
to confirm that numbing the genicular nerve reduces the patient's knee
pain. Cooled radiofrequency ablation is performed on an outpatient
basis, with local anesthesia and minimal sedation.
Patients undergoing CRFA had significant and lasting reduction in
pain scores. From an initial pain score of about 7 on a 10-point scale,
pain ratings at one month were about 3 in the CRFA group versus 4 in the
steroid group.
With further follow-up, pain scores remained lower in the CRFA group
while increasing toward the pre-treatment level in the steroid group.
At six months, 74 percent of patients assigned to CRFA had at least a
one-half reduction in pain scores, compared to 16 percent of those
undergoing steroid injection.
Forty percent of patients in the CRFA group rated their knee
function "satisfactory" at six months' follow-up, compared to just three
percent of the steroid group. Ninety-one percent of the CRFA group felt
their overall health had improved, compared to 24 percent in the
steroid group.
Patients undergoing CRFA had greater reduction in the use of
conventional, non-opioid pain medications. There was no significant
difference in opioids, which were used by a minority of patients in both
groups. There were no serious treatment-related adverse events in
either group.
The results suggest that CRFA provides "clinically meaningful" pain
reduction and functional improvement in patients with knee OA, with
better and longer-lasting improvement than steroid injection. Dr.
Kapural and colleagues plan longer follow-up to assess outcomes at one
year and beyond. They note that pain may return as the treated nerve
regenerates; if so, repeating the CRFA procedure is a "reasonable and
sensible" option.
The authors note some limitations of their study, including the fact
that the results weren't assessed in "blinded" fashion. They also
suggest more focused studies to see if CRFA can reduce the need for
opioid pain medications. Dr. Kapural and coauthors conclude,
"Nonetheless, the findings of this study indicate that CRFA for
genicular nerve ablation is superior to a single corticosteroid
injection in osteoarthritic subjects for management of knee pain."
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