Many people with osteoarthritis and other degenerative diseases, including posttraumatic pain and rheumatoid arthritis, suffer from chronic hip pain.
Although total hip arthroplasty (THA) is often performed in patients with advanced disease, the procedure is associated with:
- 5% to 15% failure rate,
- high cost, and
- increased morbidity, mortality, and
- persistent postoperative pain
In addition, the life expectancy of hip implants ranges from 10 to 25 years.
There has recently been renewed interest in radiofrequency (RF) procedures for joint pain resulting from degenerative conditions.
“Clinical studies have shown that RF treatment is more effective than conservative methods in reducing hip pain,” said Edward Heres, MD, a pain medicine expert and clinical assistant professor of anesthesiology at the University of Pittsburgh Medical Center in Pennsylvania.
“It works by interrupting the sensory input from the femoral and obturator nerves that innervate the hip joint,” he told Clinical Pain Advisor
So, if a nerve is signaling pain, they just disable the nerve. I suppose this would work, but such a procedure disables ALL signaling from that nerve, including useful sensations trying to warn about physical damage to the hip.
A review published in Regional Anesthesia and Pain Medicine examined the evidence pertaining to RF for hip pain.
The most common indication for RF was osteoarthritis, and other diagnoses included vascular necrosis and persistent pain after THA.
Participants had moderate to severe hip pain and limited ambulation, and previously demonstrated a lack of response to oral analgesics and other conservative approaches.
All studies used ablative RF, except for 2 that used pulsed RF. Most RF procedures targeted articular branches of the obturator nerve and femoral nerve.
To guide placement of the RF cannulas, all but 1 of the studies used fluoroscopy, which “is considered mandatory for improving the accuracy of ablation of articular branches of this nerve innervating the hip joint,” the authors wrote.
In all studies that involved procedures on the articular branches of the obturator nerve, the imaging landmark for needle placement was
“the point immediately inferior to the ‘teardrop’ silhouette, formed by the junction of pubic and ischial bones (often referred to as the incisura of the acetabulum),” they noted.
For procedures involving the articular branches of the femoral nerve, the imaging landmark was a
“point immediately inferior and medial to the anterior inferior iliac spine [that] corresponds to the anterolateral aspect of the extra-articular portion of the hip joint.”
All studies demonstrated reductions in pain scores after RF treatment, ranging from 30% to more than 90%.
Although most of the articles reported reductions in analgesic requirements after RF, these changes were not quantified.
If not all these articles reported reductions in analgesic requirements, that would mean they didn’t work to ease pain at all.
The few adverse effects that occurred “were usually due to vascular penetration or inadvertent ablation of extra-articular sensory and motor branches of the [obturator nerve and femoral nerve],” noted the review authors.
This is a fancy way of saying “Oops, we missed.”
The review also describes the innervation pattern of each nerve suggested as a target for RF ablation in specific types of hip-related pain, as well as recommended approaches for ablation at these sites:
- the articular branches of the obturator nerve for groin and thigh pain,
- the articular branches of nerves innervating the posterior hip joint for gluteal pain, and
- the articular branches of the femoral nerve for thigh and trochanteric pain.
“Hip pain is a common condition that is often seen in elderly patients with multiple comorbidities,” Dr Heres noted. “Often, pain medications are ineffective or have too many side effects, and injections only provide little or temporary pain relief.”
In addition, surgery may not be an option because of unwillingness of the patient or an especially high risk for complications related to comorbidities.
RF treatment may be a reasonable alternative in these circumstances, as well as in situations involving long wait times for THA or persistent pain after THA.
However, I looked up RFA in Wikipedia:
RFA, or rhizotomy, is sometimes used to treat severe chronic pain in the lower (lumbar) back, where radio frequency waves are used to produce heat on specifically identified nerves surrounding the facet joints on either side of the lumbar spine.
By generating heat around the nerve, the nerve gets ablated thus destroying its ability to transmit signals to the brain.
The nerves to be ablated are identified through injections of local anesthesia (such as lidocaine) prior to the RFA procedure. If the local anesthesia injections provide temporary pain relief, then RFA is performed on the nerve(s) that responded well to the injections.
RFA is a minimally invasive procedure which can usually be done in day-surgery clinics, going home shortly after completion of the procedure. The patient is awake during the procedure, so risks associated with general anesthesia are avoided. An intravenous line may be inserted so that mild sedatives can be administered.
Only by checking this external source did I find the serious limitation of this procedure:
a drawback for this procedure is that nerves recover function over time, so the pain relief achieved lasts for only a short duration (3-15 months) in most patients.
Nowhere in the original article did it mention that these procedures are not permanent, but need to be redone annually.