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Radiofrequency techniques to treat chronic knee pain: A comprehensive review of anatomy, effectiveness, treatment parameters, and patient selection


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Background The use of radiofrequency ablation (RFA) procedures to treat chronic knee pain has surged in the past decade, though many questions remain regarding anatomical targets, selection criteria, and evidence for effectiveness. Methods A comprehensive literature review was performed on anatomy, selection criteria, technical parameters, results of clinical studies, and complications. Databases searched included MEDLINE and Google Scholar, with all types of clinical and preclinical studies considered. Results We identified nine relevant clinical trials, which included 592 patients, evaluating knee RFA for osteoarthritis and persistent postsurgical pain. These included one randomized, placebo-controlled trial, one randomized controlled trial evaluating RFA as add-on therapy, four comparative-effectiveness studies, two randomized trials comparing different techniques and treatment paradigms, and one non-randomized, controlled trial. The results of these studies demonstrate significant benefit for both reduction and functional improvement lasting between 3 and 12 months, with questionable utility for prognostic blocks. There was considerable variation in the described neuroanatomy, neural targets, radiofrequency technique, and selection criteria. Conclusion RFA of the knee appears to be a viable and effective treatment option, providing significant benefit to well-selected patients lasting at least 3 months. More research is needed to better identify neural targets, refine selection criteria to include the use of prognostic blocks, optimize treatment parameters, and better elucidate relative effectiveness compared to other treatments.
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Radiofrequency techniques to treat chronic
knee pain: a comprehensive review of anatomy,
effectiveness, treatment parameters, and patient
David E Jamison1,2
Steven P Cohen1–6
1Department of Anesthesiology,
Walter Reed National Military
Medical Center (WRNMMC),
Bethesda, MD, USA; 2Department of
Anesthesiology, Uniformed Services
University of Health Sciences
(USUHS), Bethesda, MD, USA;
3Department of Anesthesiology and
Critical Care Medicine, Johns Hopkins
School of Medicine, Baltimore, MD,
USA; 4Department of Neurology,
Johns Hopkins School of Medicine,
Baltimore, MD, USA; 5Department of
Physical Medicine and Rehabilitation,
Johns Hopkins School of Medicine,
Baltimore, MD, USA; 6Department of
Physical Medicine and Rehabilitation,
USUHS, Bethesda, MD, USA
Background: The use of radiofrequency ablation (RFA) procedures to treat chronic knee pain
has surged in the past decade, though many questions remain regarding anatomical targets,
selection criteria, and evidence for effectiveness.
Methods: A comprehensive literature review was performed on anatomy, selection criteria,
technical parameters, results of clinical studies, and complications. Databases searched included
MEDLINE and Google Scholar, with all types of clinical and preclinical studies considered.
Results: We identified nine relevant clinical trials, which included 592 patients, evaluating
knee RFA for osteoarthritis and persistent postsurgical pain. These included one randomized,
placebo-controlled trial, one randomized controlled trial evaluating RFA as add-on therapy,
four comparative-effectiveness studies, two randomized trials comparing different techniques
and treatment paradigms, and one non-randomized, controlled trial. The results of these studies
demonstrate significant benefit for both reduction and functional improvement lasting between 3
and 12 months, with questionable utility for prognostic blocks. There was considerable variation
in the described neuroanatomy, neural targets, radiofrequency technique, and selection criteria.
Conclusion: RFA of the knee appears to be a viable and effective treatment option, providing
significant benefit to well-selected patients lasting at least 3 months. More research is needed
to better identify neural targets, refine selection criteria to include the use of prognostic blocks,
optimize treatment parameters, and better elucidate relative effectiveness compared to other
Keywords: Knee pain, osteoarthritis, radiofrequency, ablation, denervation, genicular nerve
Knee pain has a lifetime prevalence rate of ~45%,1 and represents a source of signifi-
cant disability and reduced quality of life.2,3 Risk factors for the development of knee
pain include a history of prior injury or surgery, obesity, and advancing age.4 The most
common cause of chronic knee pain is osteoarthritis (OA), which is characterized by
the progressive loss of articular cartilage, with other etiologies including rheumatoid
arthritis, trauma, crystal arthropathies, and persistent postsurgical pain.5,6
Available treatments for knee pain vary depending on the etiology and diagno-
sis, but broadly include physical therapy, oral medications, injections, and surgery.7
Injections for knee pain consist of several types, and may be directed to the soft
tissues of the knee joint or the intra-articular joint space. Intra-articular injections
encompass a wide range of medications to include anti-inflammatory corticosteroids,
Correspondence: Steven P Cohen
Department of Anesthesiology and
Critical Care Medicine, Johns Hopkins
School of Medicine, 550 North
Broadway, Suite 301, Baltimore, MD
21029, USA
Tel +1 410 955 1818
Fax +1 410 502 6730
Journal name: Journal of Pain Research
Article Designation: Review
Year: 2018
Volume: 11
Running head verso: Jamison and Cohen
Running head recto: Radiofrequency techniques to treat chronic knee pain
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Jamison and Cohen
pro-inflammatory prolotherapy and platelet-rich plasma
(PRP) solutions, viscosupplements, and stem cell prepara-
tions.8–11 All intra-articular injections require the presence
of an intact joint, and are therefore not applicable following
total arthroplasty. Knee surgery is similarly heterogeneous
and ranges from minimally invasive arthroscopic procedures
to open partial or total arthroplasties.12,13 Pain due to severe
OA is not reliably responsive to conservative therapies, and
chronic pain may persist in over 40% of patients who undergo
joint replacement, being characterized as severe in 15% of
cases.14–16 Delivery of radiofrequency (RF) energy to the
knee’s nerve supply is a relatively new intervention that can
be safely done in the presence of an artificial joint, and may
offer an alternative to surgery or surgical revision.
Radiofrequency ablation (RFA) entails the discrete
delivery of thermal energy produced by an alternating cur-
rent to neural tissue, thereby degrading its ability to conduct
pain signals.17 First described as a treatment for pain in the
1960’s,18 RFA evolved from a therapy primarily employed to
alleviate neuropathic pain to one used today predominantly
for mechanical joint pain amidst reports of increased pain
stemming from deafferentation and neuroma formation.
Since the neurosurgeon Norman Shealy adapted its use for
the treatment of pain arising from the spinal facet joints in
the mid-1970’s,19 the accepted indications for RFA have
expanded steadily over the ensuing decades. The advent
of cooled radiofrequency ablation (CRFA)20 and the non-
ablative pulsed radiofrequency (PRF)21 therapy have further
broadened the clinical utility of RF for chronic pain states.
Accepted targets for RF treatment now include most neural
structures to include major nerves and ganglia.22–24 The use
of RF as a treatment for knee pain was first described in a
small case series involving the treatment of different types of
joint pain by Sluijter et al, who noted complete eradication
of pain with intra-articular PRF in a patient with refractory
post-traumatic knee pain.25 This area of pain medicine has
evolved in the past decade, and though knee RFA has been
the subject of numerous publications, high-quality random-
ized controlled trials (RCTs) remain sparse. The objectives
of this publication are to review the relevant neuroanatomy
of the knee and the available literature on RFA.
Search strategy
We systematically searched and screened all titles and
abstracts from MEDLINE and Google Scholar from incep-
tion to February 1, 2018 using the following key words:
“knee,” “pain,” “arthritis,” “persistent postsurgical pain,
“chronic postsurgical pain,” “radiofrequency,” “ablation,
“denervation,” and “pulsed radiofrequency.” This initial
search yielded 92 trials of varying design, which were then
separately reviewed by the authors. For the purposes of this
review only randomized and comparative trials were selected,
with all other study types being excluded. A total of nine ran-
domized or comparative trials were ultimately identified by
independent searches conducted by each author. The literature
search was complemented by reviewing the reference lists
of the selected publications to search for additional articles
missed by our initial electronic search.
Neuroanatomy of the knee
The innervation of the knee joint is complex given that
genicular nerves arise from branches of three major nerves:
the sciatic, femoral, and obturator, all of which are them-
selves derived from the lumbar plexus.26,27 The sciatic nerve
bifurcates into the tibial and common peroneal nerves in
the popliteal fossa. The tibial nerve remains in the posterior
compartment of the lower leg and gives off the superomedial
(SM) and inferomedial (IM) genicular nerves to the posterior
aspect of the knee joint. The common peroneal nerve passes
into the anterior compartment of the lower leg, and contrib-
utes the superior lateral (SL) genicular nerve to the anterior
portion of the knee. These genicular branches of the sciatic
nerve reliably course in approximation to the periosteum at
the medial and lateral junctions of the distal femoral shaft and
epicondyles, and at the medial junction of the proximal tibia
and epicondyle. The saphenous nerve is a cutaneous sensory
branch of the femoral nerve and gives off suprapatellar and
infrapatellar (IP) genicular nerves to the anterior portion of
the knee. The contribution of the obturator nerve is more
variable, but its posterior branch can provide an articular
branch to the posterior knee.
The complexity of the knee joint’s innervation has
resulted in a disparity in procedural technique among the
available controlled and observational studies. Studies report
on a range of procedural targets to include the SM, IM,
and SL genicular nerves in combination,28–33 the saphenous
nerve,34 the sciatic nerve,35 the IP genicular nerve,36 the IP
and SM genicular nerves in combination,37 the femoral, tibial,
saphenous nerves, and peripatellar plexus in combination,38
and the intra-articular joint space6,25,39–41 (Figures 1 and 2).
The earliest published RCT is the 2011 study by Choi et al28
This trial was designed to compare genicular nerve RFA to
sham RFA. Nerves targeted in this trial were the SM, IM, and
SL genicular branches. Inclusion criteria were age between
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Figure 1 Anterior-posterior radiograph of the knee depicting locations for
genicular nerve targeting.
Abbreviations: IM, inferomedial; IP, infrapatellar; MR, medial retinacular; SL,
superolateral; SM, superomedial.
Figure 2 Lateral radiograph of the knee depicting locations for genicular nerve
Abbreviations: IM, inferomedial; IP, infrapatellar; MR, medial retinacular; SL,
superolateral; SM, superomedial.
50 and 80 years, presence of refractory knee pain of at least
3 months duration, and at least grade 2 radiographic evidence
of OA on the 5-point Kellgren–Lawrence scale.42 Thirty-eight
patients who met the criteria and had a positive response to
genicular nerve blocks were randomized to receive either
continuous, fluoroscopically guided RFA at 70°C, or sham
RFA that consisted of superficial and deep local anesthesia
with lidocaine. Primary outcomes were pain level as assessed
by visual analog scale (VAS) and the proportion of patients
reporting at least 50% pain relief at 12-week follow-up.
Overall follow-up was obtained at 1, 4, and 12 weeks post-
procedure. The results showed that RFA significantly lowered
the VAS at all time periods compared to sham, but both
groups showed similar improvement at 1 week, suggesting
a temporary improvement with local anesthetic nerve block.
Ten of the 19 RFA patients achieved at least 50% pain reduc-
tion at 12 weeks, compared to no patients in the control group.
Secondary outcomes to include Oxford knee score (OKS)
and patient satisfaction were also significantly improved in
the RFA group. The limitations of this study are primarily
its small size, the large discrepancy between the volume of
prognostic blocks and the small electrodes used, the high
proportion of positive prognostic blocks (82.5%), and lack
of long-term follow-up.
RFA was first compared to intra-articular injections in
the 2016 Sarı et al trial.29 Seventy-three patients with at least
grade 2 Kellgren–Lawrence OA were randomized to receive
either RFA of the SL, SM, and IM genicular nerves at 80°C
for 90 seconds or intra-articular injection of bupivacaine,
morphine, and betamethasone. Patients were assessed at
baseline, 1 and 3 months for pain level via VAS and function
via the Western Ontario and McMaster Universities Osteoar-
thritis (WOMAC) index. Results showed statistically superior
pain relief with RFA at 1 and 3 months, but superiority in
the total WOMAC score with RFA only at 1 month. Limita-
tions of the study include the lack of prognostic blocks, the
unrestricted and undocumented use of oral analgesics, and
the lack of a true control group.
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The SM, IM, and SL genicular nerves were also targeted
in the 2017 Qudsi-Sinclair et al trial, but in this trial the effect
of RFA was examined only in patients with a history of total
knee arthroplasty (TKA).30 Thirty patients with refractory
knee pain that persisted at least 6 months following TKA
were enrolled in the study, with 28 completing follow-up
to 12 months. Patients were randomized to receive either
continuous RFA at 80°C or sham RFA that consisted of
genicular nerve blocks with local anesthetic and corticoste-
roid. Both procedures were performed under fluoroscopic
guidance. Outcome measures were pain level assessed via a
numeric rating scale (NRS), and function assessed via both
the OKS and Knee Society Score. Outcomes with respect
to function were modest and similar between groups, with
most improvements occurring between months 1 and 6, and
declining toward baseline by 12 months. Pain also decreased
in both groups, but the reduction following RFA peaked at 3
months and persisted at 12 months, while the control group
experienced their lowest NRS on day 1 and then steadily
increased toward baseline at 12 months. This trial is limited
by a small size and the lack of prognostic blocks pre-RFA,
which may have led to the inclusion of nonresponders in the
RFA group.
The Shen et al trial compared RFA with PRP and sodium
hyaluronate (HA) to PRP and HA alone.43 Inclusion criteria
were refractory pain of at least 3 months duration due to
OA and pain level of at least 6 on a 0–10 VAS. Both groups
received intra-articular injections of PRP and HA weekly
for 5 weeks, but the treatment group also received RFA at
70°C, although the timing of the RFA was not described. The
precise nerves were also neither named, nor was it specified
whether image guidance was used. Twenty-seven patients
were randomized to each group and follow-up was obtained
at the completion of intra-articular injections and 3 months.
Outcome measures included pain intensity as measured on
a VAS, life quality as measured on the 36-item Short-Form
Health Survey, and function via the American Knee Society
Score. Both groups showed improvement in pain and func-
tion, although the gains in the RFA group were statistically
superior at all time periods. The RFA group also demonstrated
significant improvement in quality of life at 3 months, while
the control group did not.
The 2018 trial by Davis et al is the largest study and was
also the first to employ CRFA.31 Similar to the Qudsi-Sinclair
and Choi trials, the SM, SL, and IM genicular nerves were
targeted. Inclusion criteria were the presence of at least grade
2 Kellgren–Lawrence radiographic OA, refractory knee pain
of at least 6 month duration, pain of at least 6 of 10 on a NRS,
OKS score of at least 35, and at least 50% improvement with
genicular nerve blocks. One hundred and fifty-one patients
met the inclusion criteria and were randomized to receive
either CRFA or intra-articular steroid (IAS) injection. CRFA
was performed under fluoroscopic guidance with 17-gage
introducers at 60°C for 150 seconds. The primary outcome
was the percentage of patients achieving at least 50% pain
reduction at 6 month follow-up as measured by a NRS.
Secondary outcome measures included function measured
on OKS, patient’s overall perception of the treatment, and
analgesic usage. Pain relief with CRFA was superior to that
obtained with IAS at all time periods, and at 6 month follow-
up 74% of the CRFA group had at least 50% relief compared
to just 16% of the IAS group. Function and global perception
were also superior in the CRFA cohort, although there was
no statistical difference between the groups in terms of oral
opioid use. The longer duration of relief noted in this study
provides evidence for the theoretical benefit of CRFA, namely
the creation of larger lesions to reduce the technical failure
rate (ie, missed nerves).
The most recent RCT by El-Hakeim et al compared RFA
to non-interventional therapy.32 Sixty patients with at least
grade 3 Kellgren–Lawrence OA were randomized to receive
either RFA of the SM, SL, and IM branches or conventional
treatment with oral acetaminophen and diclofenac. RFA
was accomplished with three 90 seconds cycles at 90°C per
site, which is a substantially longer duration of RFA than
that employed by any other RCT. Patients were evaluated at
baseline, 2 weeks, 3 months, and 6 months. Results showed
statistically superior pain relief with RFA at all follow-up
intervals. Function as assessed by the WOMAC index was
improved in both groups at 6 months, but was superior with
RFA. Lastly, patient satisfaction as measured on a Likert
scale was significantly higher at 3 and 6 month follow-up in
the RFA group. However, the study is limited by the lack of
pre-RFA prognostic blocks and the lack of patient blinding.
Randomized, non-comparative studies
The 2017 randomized trial by McCormick et al also employed
CRFA, but the study was designed to determine the predic-
tive value of pre-RFA nerve blocks, not to compare RFA to
other modalities.33 Fifty-four patients with chronic knee pain
due to OA all received CRFA, but 29 did so after prognostic
blocks and 25 did not. Notably, only three of 32 (9.3%)
patients had a negative block, defined as <50% pain relief.
Some patients had the procedure done bilaterally; so a total
of 36 knees had CRFA following prognostic blocks and 35
knees proceeded directly to CRFA. Inclusion criteria were
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age between 30 and 80 years, >6 months of refractory knee
pain, NRS pain score of at least four and at least grade 2
radiographic OA. Follow-up was conducted at 1, 3, and 6
months, but the primary outcome measure was attainment of
at least 50% pain relief at the 6-month mark. Results showed
significant improvements in both groups at 6 months, with
58.6% of the nerve block group and 64% of the non-nerve
block group achieving at least 50% relief at 6 months. There
were no significant differences between groups in terms of
pain and function at any of the time periods. These findings
raise questions regarding the utility of single, uncontrolled
blocks before knee RF ablation, and suggest the need for
more research to better refine selection criteria.
The intra-articular delivery of RF energy is advocated
by some as an alternative to ablating the genicular nerves,
though studies evaluating intra-articular RFA for other con-
ditions have yielded equivocal results.44,45 A 2017 trial by
Gulec et al randomized 100 patients with chronic knee pain
for at least 3 months to receive either intra-articular bipolar
or monopolar PRF, without a control group.39 Two RF can-
nulae were placed into the anterior knee joint from either
side of the patellar ligament under fluoroscopic guidance.
PRF in all cases was delivered at 42°C for 10 minutes, but
patients and the provider were blinded as to whether it con-
sisted of bipolar energy coursing between the cannulae, or a
monopolar system set up between one of the cannulae and a
dispersive (grounding) pad. The primary outcome measure
was the percent of patients with at least 50% pain reduction
at 3-month follow-up as measured by VAS while walking
on a flat ground. The results showed superior improvements
in the bipolar group, with 84% achieving a positive primary
outcome, compared to only 50% in the monopolar group.
Limitations of this trial include the lack of a control group
and no long-term follow-up.
Comparative, non-randomized trials
The 2010 Ikeuchi et al trial compared RFA to nerve blocks,
but was not randomized.37 Nineteen patients who met the
selection criteria during one time frame received RFA, while
another nineteen patients treated within a later time frame
received sham RFA; one RFA and two control patients did not
complete the study. Inclusion criteria included radiographic
evidence of moderate to severe OA, age >65 years, and knee
pain for longer than 3 months. Patients in the RFA group
received two non-image guided, continuous RFA treatments
at 70°C at a 2-week interval. Two lesion sites were targeted,
the SM and IP genicular nerves. Patients in the control
group also received two procedures 2 weeks apart, but they
consisted only of topical and deep anesthesia with lidocaine;
RFA was not performed. Other complementary treatments
were withheld for 12 weeks, and assessment was obtained at
4 weeks, 8 weeks, 12 weeks, and 6 months. Outcome mea-
sures included the WOMAC functional assessment, VAS pain
scores, and a 4-point patient global assessment. Outcomes
were overall mixed. The total WOMAC score remained lower
in the RFA group throughout the 6 month follow-up, but the
difference was not statistically significant. VAS scores were
significantly lower in the RFA group at 4-, 8-, and 12-week
follow-ups, but the effect tapered off by 6 months. Limitations
of the this study include the lack of randomization, lack of
prognostic nerve blocks, and the targeting of only two nerve
branches (Table 1).
RFA predictors of outcome
Predictors of success or failure with RFA relate to both patient
characteristics and procedural technique. This subject has been
reported extensively as it relates to other pain interventions,
notably lumbar facet and sacroiliac joint (SIJ) RFA. Patient
factors predictive of failure with SIJ RFA include age >65 years,
higher baseline pain level, and opioid use.46 Patient factors
predictive of poor success with lumbar or cervical RFA include
advanced age, certain pain referral patterns and physical exam
signs, opioid use, prior history of depression, previous back
surgery, longer duration of pain, and ongoing legal action.47–49
In individuals with chronic neck pain due to whiplash, low
levels of pain catastrophizing and functional disability were
found to be predictive of success with cervical RFA.50 In a
study evaluating prognostic factors before PRF of the occipital
nerves, treatment failure was associated with extension of pain
beyond the confines of the targeted nerve distribution, while a
lower diagnostic block volume, multiple treatment cycles, and
a traumatic precipitating event predicted success.51
Procedural factors that contribute to success with RFA
include the type of RF energy applied, the duration and tem-
perature of treatment, and the gage of the RF probe itself. An
ex vivo trial compared several types of RF and found that
CRFA created larger lesions than either continuous or PRF.52
Within RFA and PRFA groups, larger probes and longer dura-
tion of treatment were associated with larger lesions. Results
from studies on SIJ RFA have been mixed, with one reporting
superior relief with CRFA when compared to RFA,53 one
showing a trend toward superiority with CRFA,54 and another
demonstrating no difference.55 Orientation of the RF probe
parallel to the targeted nerve has also been demonstrated in
preclinical studies to create larger lesions,56 but results from
uncontrolled trials are mixed.55,57
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Table 1 Randomized and comparative studies
Trial Study
Trial size,
RF method Anatomic
Results Comment
Choi et al28 RCT 38, OA RFA (70°C, 90 seconds) + LA
vs sham
SM, SL, IM Yes 12 weeks RFA > sham for pain and function
at 4 and 12 weeks
High volume (2 mL) used for prognostic
Sarı et al29 RCT 73, OA RFA (80°C, 90 seconds) vs IA
steroid, LA, and morphine
SM, SL, IM No 3 months RFA superior for pain and function No prognostic blocks
Shen et al43 RCT 54, OA RFA (70°C, 120 seconds) +
PRP + HA vs PRP + HA
No 3 months RFA superior for pain and function Nerves targeted not described, unclear if
imaging guidance was used
et al30
RCT 28, post-
RFA (80°C, 90 seconds) vs LA
+ steroid
SM, SL, IM No 12 months RFA > nerve block for pain at 12
months; functional relief modest
and not different between groups
Signicant short-term relief with nerve
blocks. Functional improvement modest
and not statistically different between
Davis et al31 RCT 151, OA Cooled RFA (60°C, 150
seconds) vs IA steroid
SM, SL, IM Yes 6 months RFA > IA injections for pain and
No difference in opioid usage between
et al32
RCT 60, OA RFA (90°C, 270 seconds) vs PO
acetaminophen and NSAIDs
SM, SL, IM No 6 months RFA superior for pain and function Patients not blinded
et al33
RCT 53, OA Cooled RFA (60°C, 150
seconds) either after or
without prognostic nerve block
SM, SL, IM Yes/no 6 months Both groups improved in pain and
function, no difference between
29 of 32 patients in the nerve block group
received RFA
Gulec et al39 RCT 100, OA Bipolar vs monopolar IA PRF
(42°C, 10 minutes)
IA No 12 weeks Bipolar > monopolar RFA for pain
relief at 12 weeks
No control group
Ikeuchi et al37 CS-P 35, OA RFA (70°C, 90 seconds) + LA
vs LA
SM, IP No 6 months RFA > LA for pain at 12 weeks Not image guided, non-randomized
Abbreviations: CS-P, case series, prospective; HA, hyaluronic acid; IA, intra-articular; IM, inferomedial; IP, infrapatellar; LA, local anesthetic; NSAID, nonsteroidal anti-inammatory drug; OA, osteoarthritis; PO, per os; PRF, pulsed
radiofrequency; PRP, platelet-rich plasma; RCT, randomized controlled trial; RF, radiofrequency; RFA, radiofrequency ablation; SL, superolateral; SM, superomedial; TKA, total knee arthroplasty.
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The predictive value of prognostic genicular nerve blocks
prior to RFA is similarly questionable. Among the eight RCTs
discussed, only three employed positive response to nerve
block as a criterion for the performance of RFA. The Choi
et al trial, which is the only RCT to compare RFA to sham,
required a positive response to prognostic nerve blocks for
patients to proceed to the RF portion of the study.28 However,
2 mL lidocaine per site was used to perform the nerve blocks,
and a positive response was defined as at least 50% pain
relief lasting for 24 hours. Higher volume local anesthetic
nerve blocks have been shown to decrease the specificity of
prognostic blocks as local anesthetics may spread farther than
a subsequent RF lesion,51 and pain relief lasting 24 hours is
inconsistent with the pharmacodynamics of lidocaine.
The McCormick et al trial specifically addressed the prog-
nostic value of nerve blocks by comparing RFA outcomes per-
formed after positive genicular nerve blocks to results obtained
without the use of prior injections.33 Blocks were performed with
1 mL of lidocaine, with a positive response defined as 50%
pain reduction persisting for at least 1 hour following injection.
Given the lack of statistical difference between the groups, the
authors concluded that their method of genicular nerve block
has little prognostic value. Methods postulated by the authors to
increase the prognostic utility of genicular nerve blocks include
the use of a higher threshold for defining a positive response to
nerve blocks (90% relief), or using double comparative nerve
blocks. However, studies evaluating the effect of using higher
cutoffs to select patients for SIJ and lumbar and cervical RFA
have mostly found no improvement in outcomes.46,58,59 The use
of comparative medial branch blocks with local anesthetics of
differing durations of action is also of unclear benefit, having
been shown to have marginal sensitivity60 and little impact on
lumbar facet RFA outcomes61,62 (Table 2).
No major adverse events were reported in any randomized or
observational trial. All patients in the RF limb of the Ikeuchi
trial noted 2–6 weeks of hypoesthesia in the IP region, but
these symptoms self-resolved.37 A review in 2016 discussed
the potential adverse effects of knee RFA given the proximity
of genicular arteries to the genicular nerves.63 Multiple
genicular arteries arise from the popliteal artery, and they
course along the epicondyles of the distal femur and proximal
tibia in the region where the SL, SM, and IM genicular nerves
are normally targeted64 (Figure 3). Injuries to the genicular
arterial system are described in the surgical literature, from
both open and arthroscopic procedures, and sequelae include
pseudoaneurysm formation, hemarthrosis, arteriovenous
fistula formation, and patellar osteonecrosis.65–68 The authors
are also aware of several unpublished reports of skin burns,
which may arise because of the close proximity of the target
nerves to the skin. Other potential complications include
those generic to other interventional procedures, namely
infection, bleeding, or bruising. Intra-articular approaches
also confer the risk of joint sepsis or chondrolysis, but these
have not been described following RFA.
Chronic knee pain is a recent addition to the growing list
of indications for RF, having first been described only a
Table 2 Factors associated with radiofrequency ablation treatment outcomes for knee pain and other conditions
Predictors of success Predictors of failure
Medial compartment osteoarthritis and concordant pain Greater disease burden (eg, longer duration of symptoms, greater disability)
Large and/or multiple lesions Previous surgery
Controlled prognostic blocks Opioid use
Diffuse pain symptomatology (bromyalgianess)
Figure 3 Anterior-posterior radiograph of the knee with overlay of the genicular
Abbreviations: LI, lateral inferior; LS, lateral superior; MI, medial inferior; MS,
medial superior.
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decade ago. Among the eight RCTs found in the literature,
six compared knee RFA to sham28,30 or other accepted
treatments,29,31,32,43 but all demonstrated superior pain relief
and function with RFA.28–33,37,39,43 Fundamental differences
between studies make the aggregate body of literature dif-
ficult to interpret, as the type of RFA and the anatomic targets
vary considerably. However, the preponderance of evidence
suggests that RF denervation can be a safe and effective
treatment for chronic knee pain, with the duration of benefit
similar to that targeting other joints, ranging between 3 and
12 months.
The use of PRF for knee pain is not well supported, and
was featured in only one RCT that compared two types of
PRF, without a control group.39 PRF is generally acknowl-
edged as an effective treatment for neuropathic pain based on
dozens of preclinical studies and numerous clinical trials.69–72
Considering that knee arthritis is a non-neuropathic pain
condition, the conceptual basis for the use of PRF in this
condition (ie, neuromodulation without significant injury to
the neural architecture) is lacking. RCTs comparing PRF to
RFA for lumbar facet joint pain have shown greater and more
sustained pain relief with continuous RFA, raising further
questions regarding its utility for knee pain.73,74 Although
pain was improved compared to baseline in the PRF groups
of both studies, these differences were small and may be
attributable to a placebo response. In any case, these results
are not easily extrapolated to PRF of the knee given that the
targets were neural structures (ie, the medial branch nerves),
and not the intra-articular space.
The utility of prognostic blocks prior to RFA is also
unclear. Employment of a higher pain relief threshold and the
use of comparative local anesthetic blocks may increase the
specificity of prognostic blocks, but at the inevitable cost of
decreased sensitivity (ie, increased false-negative results).60,62
The primary downside for a prognostic procedure associated
with a high false-negative rate is the denial to patients of a
safe and effective RFA procedure.
It should be acknowledged that comparisons to and from
the spine pain literature regarding RFA are based primarily on
the similarity of the intervention, not on similarities in pathol-
ogy or anatomy. Therefore, in addition to neuroanatomical
studies and large multicenter studies that further elucidate
the benefit of knee RFA in comparison to sham ablation
(ie, placebo-controlled studies), different types of ablation
(eg, cooled vs conventional, techniques targeting different
genicular nerves and anatomical locations), and alternative
treatments (ie, comparative-effectiveness studies), other areas
ripe for future research include modification of facet and SIJ
RFA trials that have shed light on patient selection criteria,
and the effects of prognostic nerve blocks on RFA outcomes.
The assistance offered by the Center for Rehabilitation
Sciences Research, Bethesda, MD, USA is gratefully
SPC has served as a consultant to Halyard, Boston Scientific,
and Abbott within the past 3 years. The opinions or assertions
contained herein are the private views of the authors and are
not to be construed as official or as reflecting the views of the
Department of the Army or the US Department of Defense.
The authors report no other conflicts of interest in this work.
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... Nerve ablation is a nonpharmaceutical treatment option for OA of multiple joints, including the hip, shoulder, and knee [63][64][65]. Different delivery methods such as radiofrequency ablation (RFA), cryoablation, and the administration of caustic chemicals are used to denature sensory nerves that transmit pain signals. Because the treatment does not eliminate the ability for nerve regrowth and regeneration, pain may return after treatment [66]. ...
... The femoral and obturator nerves are typically targeted in the treatment of hip OA [63] (Fig. 6), whereas the suprascapular, axillary, and lateral pectoral nerves are typical targets for the treatment of glenohumeral OA [64]. The superomedial, inferomedial, and superolateral genicular nerve branches are the primary targets of nerve ablation for knee OA [65]. An additional nerve branch, the medial retinacular branch, has also been found to provide consistent sensory innervation of the anterosuperior knee joint, and a nerve ablation technique in which the medial retinacular nerve is target- ed in addition to the three genicular branches has been proposed for the treatment of knee OA (Fig. 7). ...
Background: CT guidance may be used for biopsy of indeterminate bone lesions detected by MRI or PET that are not visible (i.e., occult) by CT due to equipment-, patient-, and operator-related factors. Objective: To assess diagnostic yield (DY) and diagnostic performance of CT-guided core needle biopsy (CNB) of occult non-spinal bone lesions and to identify the most common benign and malignant diagnoses for occult lesions undergoing CNB. Methods: This retrospective study included 1033 adult patients who underwent CT-guided non-spinal bone CNB between January 2004 and December 2020. Lesions were classified as occult or visible on CT; biopsies of occult lesions relied on targeting anatomic landmarks using prebiopsy MRI or PET/CT. Pathologic results of CNB were classified as diagnostic or nondiagnostic to calculate DY of CNB. For nondiagnosti CNBs, final diagnoses were established by subsequent pathologic, clinical, and imaging follow-up. Results: The sample included 70 occult lesions (mean age, 56.8 years; 38 women, 32 men) and 963 visible lesions (59.6 years; 475 women, 488 men). Malignancy rate was lower for occult than visible lesions (42.9% vs 60.8%; p=.004). DY was lower for occult than visible lesions (37.1% vs 76.9%; p<.001). Diagnostic performance for detecting malignancy based on final diagnoses was lower for occult than visible lesions in terms of sensitivity (76.7% vs 93.7%; p=.003), specificity (7.9% vs 54.5%; p<.001), and accuracy (38.2% vs 80.0%; p<.001). Final diagnoses among malignant occult and visible lesions included metastasis (frequencies of 63.3% vs 65.4%), lymphoma/leukemia (33.3% vs 11.6%), and myeloma (3.3% vs 10.4%); final diagnoses among benign occult and visible lesions included red marrow (34.2% vs 8.2%), reactive marrow (26.3% vs 11.8%), and fracture (18.4% vs 3.8%). Occult lesions detected by MRI versus by PET/CT had lower malignancy rate (39.3% vs 68.0%; p=.03) and lower DY (30.4% vs 60.0%; p=.01). Conclusion: At CT-guided CNB, malignancy rate and DY are lower for occult than visible lesions. Leukemia/lymphoma and red marrow are more common among occult than visible lesions. Clinical Impact: Understanding these characteristics can help guide radiologists', referring providers', and patients' expectations when requesting and performing CNB of occult bone lesions.
... Original research with improved outcomes, suggesting more aggressive lesioning strategies may be necessary to optimize treatment outcomes. This finding is supported by anatomical studies demonstrating significant variability in the course and ideal RF targeting points of the genicular nerves, [10][11][12] and a cadaveric study showing better nerve capture rates when cooled RFA is used than when conventional RFA is employed, which was attributed to the larger lesions created amidst anatomical variations. 13 Bipolar RFA uses symmetrically placed active electrodes that serve as a conduit for electrical current, resulting in larger lesions than conventional monopolar RFA. ...
Full-text available
Background Variability in anatomy in the knees supports the use of aggressive lesioning techniques such as bipolar-radiofrequency ablation (RFA) to treat knee osteoarthritis (KOA). There are no randomized controlled trials evaluating the efficacy of bipolar-RFA. Methods Sixty-four patients with KOA who experienced >50% pain relief from prognostic superomedial, superolateral and inferomedial genicular nerve blocks were randomly assigned to receive either genicular nerve local anesthetic and steroid injections with sham-RFA or local anesthetic and steroid plus bipolar-RFA. Participants and outcome adjudicators were blinded to allocation. The primary outcome was Visual Analog Scale pain score 12 months postprocedure. Secondary outcome measures included Western Ontario and McMaster Universities Arthritis (WOMAC) and Patient Global Improvement-Indexes (PGI-I). Results Both groups experienced significant reductions in pain, with no significant differences observed at 12 months (reduction from 5.7±1.9 to 3.2±2.6 in the RFA-group vs from 5.0±1.4 to 2.6±2.4 in the control-group (p=0.40)) or any other time point. No significant changes were observed between groups for WOMAC and PGI-I at the primary endpoint, with only the control group experiencing a significant improvement in function at 12-month follow-up (mean reduction from 91.2±38.2 to 67.1±51.9 in the RFA-group (p=0.06) vs from 95.8±41.1 to 60.6±42.8 in the control group (p=0.001); p=0.85 between groups). Conclusion Our failure to find efficacy for genicular nerve RFA, coupled with evidence showing that a plenitude of nerves supply the knee joint and preliminary studies indicating superiority of lesioning strategies targeting more than three nerves, suggest controlled trials using more aggressive lesioning strategies are warranted. Trial registration number TCTR20170130003.
... At the time of this manuscript, eight RCTs on GNA have been completed, all of which demonstrated efficacy in reducing pain and safety by ablating the SM, SL and IM genicular nerves. [173][174][175] The first of these was published by Alcidi et al in 2007 on 40 patients treated with GNA and then followed for 1 month. The authors demonstrated significant improvements in pain and function as compared to control (TENS). ...
Full-text available
Knee pain is second only to the back as the most commonly reported area of pain in the human body. With an overall prevalence of 46.2%, its impact on disability, lost productivity, and cost on healthcare cannot be overlooked. Due to the pervasiveness of knee pain in the general population, there are no shortages of treatment options available for addressing the symptoms. Ranging from physical therapy and pharmacologic agents to interventional pain procedures to surgical options, practitioners have a wide array of options to choose from - unfortunately, there is no consensus on which treatments are "better" and when they should be offered in comparison to others. While it is generally accepted that less invasive treatments should be offered before more invasive ones, there is a lack of agreement on the order in which the less invasive are to be presented. In an effort to standardize the treatment of this extremely prevalent pathology, the authors present an all-encompassing set of guidelines on the treatment of knee pain based on an extensive literature search and data grading for each of the available alternative that will allow practitioners the ability to compare and contrast each option.
... A high-quality, double-blind, sham-controlled study showed that cryoneurolysis targeting the infrapatellar branch of the saphenous nerve resulted in reduced pain and improved osteoarthritis symptoms. 7 Other studies have demonstrated RFA to be an effective modality to decrease pain and increase functionality in patients with OA. [8][9][10][11] In addition, two RCTs comparing intra-articular (IA) corticosteroids with GNRFA have shown favorable pain and function scores for ablation within the first three months and persisting to at least 6 months. 12,13 The evidence for RFA is well summarized in a recent systematic review, which concluded that RFA has superior results to NSAIDs and IA corticosteroids with no serious adverse events reported. ...
Full-text available
Introduction: Genicular nerve radiofrequency ablation (GNRFA) is an increasingly used nonsurgical treatment modality for patients with advanced knee osteoarthritis. Previous studies have demonstrated this to be an effective and safe method to decrease pain and increase functionality in this patient population. The purpose of this study was to compare 2-year postoperative complication rates and rates of prolonged postoperative opioid usage between patients undergoing total knee arthroplasty (TKA) after previous GNRFA and those undergoing TKA alone. Methods: Patients who underwent primary TKA after prior GNRFA (GNRFA-TKA) of the ipsilateral knee were identified in a national all-payer claims database from 2010 to 2019. Univariate and multivariable analyses were conducted comparing those with prior GNRFA and those without. Outcomes of interest included prolonged postoperative opioid usage, 2-year revision rates, and 90-day medical complications. Statistical analysis was conducted using R software provided by the PearlDiver Database. Results: In total, 675 patients in the GNRFA-TKA cohort were compared with a control cohort of 255,351 patients. Genicular nerve radiofrequency ablation-total knee arthroplasty patientshad lower odds of prolonged opioid use postoperatively (OR: 0.478; 95%: 0.409 to 0.559; P < 0.001). No notable difference was observed in the 2-year surgical outcomes between cohorts. Patients in the GNRFA-TKA cohort had lower odds of requiring a blood transfusion and having postoperative anemia, all arrhythmias, and urinary infections compared with primary TKA control patients. Conclusion: Preoperative GNRFA leads to a lower rate of prolonged postoperative opioid use in patients undergoing TKA, without an increased risk of complications. Future prospective studies are needed to validate the findings of this database study.
... [12][13][14] Studies have demonstrated that both t-RFA and c-RFA are effective in treating patients with CKP. [15][16][17][18][19][20][21][22] When compared with conservative treatments for CKP, either t-RFA or c-RFA is associated with superior outcomes in areas including pain score reduction, opioid medication de-escalation, and improvement of function. 17 22-26 However, to the best of our knowledge, there has been no prospective or retrospective outcomes or adverse event study comparing c-RFA and t-RFA of the genicular nerves. ...
Introduction Genicular nerve radiofrequency ablation (GNRFA) is a minimally invasive intervention for patients with chronic knee pain (CKP) not responding to conservative treatments. Few investigations have compared treatment outcomes of cooled-RFA (c-RFA) and thermal-RFA (t-RFA), two common approaches of GNRFA. This study aims to investigate and compare outcomes, including probability of treatment success, between c-RFA and t-RFA in patients with CKP. Methods This retrospective cohort study analyzed a total of 208 propensity score matched patients, including 104 patients who received c-RFA and 104 patients who received t-RFA. The primary outcome was probability of pain relief after the procedure, defined as reduction in Numeric Rating Scale (NRS) pain score of 2 or greater. The secondary outcomes were degree of NRS pain score reductions, duration of relief, and the probability of patients receiving TKA within 1 year of treatment. Results T-RFA was associated with a higher probability of pain relief within 1, 3, and 6 months after procedure when compared with c-RFA. Probabilities of pain relief from t-RFA and c-RFA were 62% (95% CI 51% to 71%) and 43% (95% CI 34% to 53%; p=0.01) within 1 month, 78% (95% CI 68% to 85%) and 55% (95% CI 45% to 64%; p<0.001) within 3 months, and 79% (95% CI 70% to 86%) and 59% (95% CI 49% to 68%; p<0.01) within 6 months, respectively. t-RFA was also associated with greater mean NRS pain score reduction at 1 month after procedure: −4.71 (95% CI −5.3 to −4.1) when compared with −3.59 (95% CI −4.3 to −2.9; p=0.02) from c-RFA. T-RFA and c-RFA were comparable in pain score reduction at 3, 6, 9 and 12 months after procedure. Both groups demonstrated comparable duration of relief and probability of patients receiving TKA within 1 year. Discussion Both t-RFA and c-RFA effectively reduced NRS pain scores in most patients with CKP within the 1 year follow-up period. Genicular nerve t-RFA was associated with a higher probability of treatment success and a greater degree of pain relief at 1 month after the procedure when compared with c-RFA in propensity score matched patients with CKP.
... This lability makes it difficult to reliably determine disease severity, particularly when imaging studies are clinically not indicated to make an OA diagnosis and thus not routinely ordered [23]. Although significant strides have been made in evidence-based clinical algorithms and care guidelines have been established, the data to guide clinical treatment decision making is still limited [8,[24][25][26][27]. Understanding the burden of OA is key to determining the most beneficial preventative strategies and the potential therapeutic interventions that would have the most beneficial impact [28,29]. ...
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Introduction: Osteoarthritis (OA) is a complex disease, and prior studies have documented the health and economic burdens of patients with OA compared to those without OA. Our goal was to use two strategies to further stratify OA patients based on both pain and treatment intensity to examine healthcare utilization and costs using electronic records from 2001 to 2018 at a large integrated health system. Methods: Adult patients with ≥1 pain numerical rating scale (NRS) and diagnosis of OA were included. Pain episodes of ≥90 days were defined as mild (0-3), moderate (4-6), or severe (7-10) based on initial NRS. Patients were initially classified as mild and moved to moderate-severe OA if any of eight treatment-based criteria were met. Outpatient visits (OP), emergency department visits (ED), inpatient days, and healthcare costs (both all-cause and OA-specific) were compared among pain levels and OA severity levels as frequencies and per-member-per-year rates, using generalized linear regression models adjusting for age, sex, and body mass index, with contrasts of p < 0.05 considered significant. Results: We identified 127,656 patients, 92,576 with pain scores. Moderate and severe pain were associated with significantly higher rates of OA-related utilization and costs, and all-cause ED visits and pharmacy costs. Moderate-severe OA patients had significantly higher OA-related utilization and costs, and all-cause OP, ED and pharmacy costs. Conclusions: Pain and treatment intensity were both strongly associated with OA-related utilization but not consistently with all-cause utilization. Our results provide promising evidence of better criteria and approaches for predicting disease burden and costs in the future.
Intraarticular knee injections have become increasingly popular over the last few decades for management of knee pain, with a variety of approaches and indications. Their use is particularly utilized for non-operative management of knee osteoarthritis. The knee joint may be approached by superior, inferior and lateral fashions. The material injected varies by indication. Overall, this intervention provides effective short-term analgesia. The procedure is technically simple, well-tolerated, and may be repeated as necessary.KeywordsIntraarticular knee injectionKnee painKnee osteoarthritisRegional anesthesiaSteroidsKnee replacementChronic knee painUltrasonography
Background There has been a surge in interest in radiofrequency ablation (RFA) of the genicular nerves over the past decade, with wide variability in selection, technique and outcomes. The aim of this study is to determine factors associated with treatment outcome. Methods We retrospectively evaluated the effect of 23 demographic, clinical and technical variables on outcomes in 265 patients who underwent genicular nerve RFA for knee pain at 2 civilian and 1 military hospital. A primary outcome was designated as a > 30% decrease in average knee pain score lasting at least 3 months without cointerventions. Results The overall rate of a positive response was 61.1% (95% CI 55.2% to 67.0%). In univariable analysis, larger electrode size (p=0.01), repeated lesions (p=0.02), having > 80% pain relief during the prognostic block (p=0.02), not being on opioids (p=0.04), having no coexisting psychiatric condition (p=0.02), having a lower baseline pain score (p=0.01) and having >3 nerves targeted (p=0.02) were associated with a positive outcome. In multivariate logistic analysis, being obese (OR 3.68, 95% CI 1.66 to 8.19, p=0.001), not using opioids (OR 0.35, 95% CI 0.16 to 0.77, p=0.009), not being depressed (OR 0.29, 95% CI 0.10 to 0.82, p=0.02), use of cooled RFA (OR 3.88, 95% CI 1.63 to 9.23, p=0.002) and performing multiple lesions at each neural target (OR 15.88, 95% CI 4.24 to 59.50, p<0.001) were associated with positive outcome. Conclusions We identified multiple clinical and technical factors associated with treatment outcome, which should be considered when selecting patients for RFA treatment and in the design of clinical trials.
Osteoarthritis is one of the most common diseases worldwide and is expected to increase in incidence as the general population age rises. Both oral medications, such as NSAIDs, and surgical treatments used for osteoarthritis management have limitations. Demand is rising for minimally invasive techniques such as intra-articular injections and percutaneous interventions for use in place of or in conjunction with oral medications and surgical therapies, and the past two decades have seen a rapid expanse in both pharmacologic and non-pharmacologic minimally invasive osteoarthritis treatments. Image guidance with fluoroscopy, CT, or ultrasound is often used in conjunction with these procedures to achieve precise treatment localization to achieve maximal therapeutic effect. The choice of modality used for image guidance is often influenced by clinician experience, patient characteristics, and equipment availability. This article reviews mechanisms of action, contraindications, complications, and efficacy of conventional and developing minimally invasive osteoarthritis treatments. Minimally invasive treatment options described in this review include therapeutic injections such as anti-inflammatory agents, viscosupplements, and biologics, as well as non-pharmacologic treatments of subchondroplasty, nerve ablation, genicular artery embolization, intra-articular pulsed radiofrequency therapy, and MR-guided focused ultrasound therapy.
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Background: Nowadays, pain and disability due to chronic knee arthritis is a very common problem in middle aged people. A lot of modalities for management are available, including conservative analgesics and up to surgical interventions. Radiofrequency ablation of genicular nerves is assumed to be an effective less invasive and safe pain alleviation modality. Objectives: To evaluate the efficacy of fluoroscopic guided radiofrequency neurotomy of the genicular nerves for alleviation of chronic pain and improvement of function in patients with knee osteoarthritis. Study design: A single-blind randomized controlled trial. Setting: Pain management unit, and Rheumatology and Rehabilitation clinics of Assiut University hospitals, Assiut, Egypt. Methods: This study involved 60 patients with chronic knee osteoarthritis. Radiofrequency neurotomy of the genicular nerves was done for 30 patients (Group A) while the other 30 patients (Group C) received conventional analgesics only. The outcome measures included visual analog scale (VAS), Western Ontario and McMaster Universities Index (WOMAC), and Likert scale for patient satisfaction in the 2nd week,3rd, and 6th months. Results: There were significant differences regarding the VAS in the 2nd week, 3rd, and 6th months between the 2 groups, and a significant difference in total WOMAC index in the 6th month only. There were significant changes when comparing pretreatment values with the values during the whole follow-up period with regard to the VAS and total WOMAC index in both groups. Limitations: No diagnostic block was done prior to radiofrequency. We recommend the use of such a technique on a larger number of OA patients, with a longer follow-up period. Conclusion: RF can ameliorate pain and disability in chronic knee osteoarthritis in a safe and effective manner. Key words: Chronic pain, radiofrequency (RF), knee osteoarthritis.
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Objectives: To evaluate the main symptoms of knee osteoarthritis (OA) and tissue structure changes after a single dose bone marrow-derived mononuclear cell (BM MNC) intra articular injection. Case series study. Patients with knee OA Kellgren Lawrence (K-L) grade II and III received 1 injection of BM MNC. The clinical results were analyzed with the Knee injury and Osteoarthritis Outcome Score (KOOS) and Knee Society Score (KSS) before, 3, 6, and 12 months after injection. Radiological evaluation was performed with a calibrated x-ray and the magnetic resonance (MR) imaging before and 6 to 7 months postinjection. Results: A total of 34 knees were treated with BM MNC injections. Mean (±SD) age of patient group was 53.96 ± 14.15 years; there were 16 males, 16 females, KL grade II, 16; KL grade III, 18. The average injected count of BM MNCs was 45.56 ± 34.94 × 106 cells. At the endpoint of 12 months 65% of patients still had minimal perceptible clinical improvement of the KOOS total score. The mean improvement of KOOS total score was +15.3 and of the KSS knee score was +21.45 and the function subscale +27.08 ( P < 0.05) points. The Whole Organ Magnetic Resonance Imaging Score (WORMS) improved from 44.31 to 42.93 points ( P < 0.05). No adverse effects after the BM-MNC injection were observed. Conclusions: The single dose BM MNC partially reduces clinical signs of the knee osteoarthritis stage II/III and in some cases, decreases degenerative changes in the joint building tissue over 12-month period.
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Background: Sphenopalatine ganglion is the largest collection of neurons in the calvarium outside of the brain. Over the past century, it has been a target for interventional treatment of head and facial pain due to its ease of access. Block, radiofrequency ablation, and neurostimulation have all been applied to treat a myriad of painful syndromes. Despite the routine use of these interventions, the literature supporting their use has not been systematically summarized. This systematic review aims to collect and summarize the level of evidence supporting the use of sphenopalatine ganglion block, radiofrequency ablation and neurostimulation. Methods: Medline, Google Scholar, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases were reviewed for studies on sphenopalatine ganglion block, radiofrequency ablation and neurostimulation. Studies included in this review were compiled and analyzed for their treated medical conditions, study design, outcomes and procedural details. Studies were graded using Oxford Center for Evidence-Based Medicine for level of evidence. Based on the level of evidence, grades of recommendations are provided for each intervention and its associated medical conditions. Results: Eighty-three publications were included in this review, of which 60 were studies on sphenopalatine ganglion block, 15 were on radiofrequency ablation, and 8 were on neurostimulation. Of all the studies, 23 have evidence level above case series. Of the 23 studies, 19 were on sphenopalatine ganglion block, 1 study on radiofrequency ablation, and 3 studies on neurostimulation. The rest of the available literature was case reports and case series. The strongest evidence lies in using sphenopalatine ganglion block, radiofrequency ablation and neurostimulation for cluster headache. Sphenopalatine ganglion block also has evidence in treating trigeminal neuralgia, migraines, reducing the needs of analgesics after endoscopic sinus surgery and reducing pain associated with nasal packing removal after nasal operations. Conclusions: Overall, sphenopalatine ganglion is a promising target for treating cluster headache using blocks, radiofrequency ablation and neurostimulation. Sphenopalatine ganglion block also has some evidence supporting its use in a few other conditions. However, most of the controlled studies were small and without replications. Further controlled studies are warranted to replicate and expand on these previous findings.
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Background and objectives: Osteoarthritis (OA) of the knee affects the aging population and has an associated influence on the health care system. Rigorous studies evaluating radiofrequency ablation for OA-related knee pain are lacking. This study compared long-term clinical safety and effectiveness of cooled radiofrequency ablation (CRFA) with intra-articular steroid (IAS) injection in managing OA-related knee pain. Methods: This is a prospective, multicenter, randomized trial with 151 subjects with chronic (≥6 months) knee pain that was unresponsive to conservative modalities. Knee pain (Numeric Rating Scale [NRS]), Oxford Knee Score, overall treatment effect (Global Perceived Effect), analgesic drug use, and adverse events were compared between CRFA and IAS cohorts at 1, 3, and 6 months after intervention. Results: There were no differences in demographics between study groups. At 6 months, the CRFA group had more favorable outcomes in NRS: pain reduction 50% or greater: 74.1% versus 16.2%, P < 0.0001 (25.9% and 83.8% of these study cohorts, respectively, were nonresponders). Mean NRS score reduction was 4.9 ± 2.4 versus 1.3 ± 2.2, P < 0.0001; mean Oxford Knee Score was 35.7 ± 8.8 vs 22.4 ± 8.5, P < 0.0001; mean improved Global Perceived Effect was 91.4% vs 23.9%, P < 0.0001; and mean change in nonopioid medication use was CRFA > IAS (P = 0.02). There were no procedure-related serious adverse events. Conclusions: 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 with painful knee OA when compared with IAS injection. Clinical trial registration: (NCT02343003).
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Background: Disorders of the facet joints are some of the most common sources of chronic spinal pain. Facet joint pain is responsible for approximately 50% of patients with chronic neck pain. Pulsed radiofrequency (PRF) stimulation, after placing needle electrodes into the joint space, has been recently reported for the management of joint pain. Objective: The aim of this study was to evaluate the effect of intraarticular (IA) PRF for the management of cervical facet joint (CFJ) pain. In addition, we compared the effect of IA PRF to IA corticosteroid injection. Study design: Prospective observational study. Setting: University hospital. Methods: Forty patients with CFJ pain were included in the study and randomly assigned to one of 2 groups: the IA PRF group and the IA corticosteroid (ICI) group. There were 20 patients in each group. Pain intensity was evaluated using a numeric rating scale (NRS) at pre-treatment, and one, 3, and 6 months after treatment. Results: When compared to the pretreatment NRS scores, patients in both groups showed a significant decrease in NRS scores at one, 3, and 6 months after treatment (P = 0.000). Changes in the NRS scores over time were not significantly different between the groups (P = 0.227). Six months after treatment, 10 patients (50.0%) in the PRF group and 12 patients (60.0%) in the ICI group reported successful pain relief (pain relief of = 50%). Limitations: A small number of participants. Conclusion: IA PRF stimulation is as effective as IA corticosteroid injection in attenuating CFJ pain. The use of PRF could decrease CFJ pain, while avoiding the adverse effects of steroids.Key words: Cervical facet joint pain, pulsed radiofrequency, intraarticular stimulation, chronic pain, corticosteroid injection, numeric rating scale.
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Background: Radiofrequency (RF) ablation for denervation has been utilized for decades in chronic pain management. This relies on the proper targeting of the affected nerve which may be obtained by creating an ablation lesion with a shape and volume that optimizes targeting. Various systems designed to improve lesion size are available. These include cooling the active tip (cooled-RF) and protruding the RF electrode outside the active tip (PERF). Objectives: This study compares lesion volumes of 3 commercially available RF systems: cooled-RF, "V" shaped active cannula and protruding electrode (18 g and 20 g), and monopolar RF (MRF; 16 g, 18 g, and 20 g). Study design: Ex vivo study using clinically relevant conditions. Setting: Biophysical laboratory in an academic institution. Methods: RF ablation lesions were generated in additive-free chicken breast specimens (n = 10) with the RF probes fully inserted in them. For cooled RF, a 17 g probe (4 mm active tip) was used. RF was applied for 150 seconds at 60°C. PERF was applied using 18 g or 20 g introducers (10 mm active tip) for either 90 or 150 seconds at 80°C. For MRF ablation, introducers diameter were 16 g, 18 g, or 20 g (10 mm active tip), while RF was applied for 90 seconds at 80°C. Tissues were dissected through the midpoint of the lesion, and measurements of the longitudinal, transversal, and depth lengths were taken and used to calculate the lesion volume. Measurements from the distal edge in the transverse and longitudinal directions were also recorded. One-way ANOVA was used to determine statistical significance between volume means (P < 0.05). Results: Mean lesion volume with cooled RF (595 mm3) is significantly larger than any other mean volume measured. The second largest volume is produced with MRF using a 16 g introducer (360 mm3), which is significantly larger than those obtained with 18 g or 20 g. This is also significantly larger than the one obtained with PERF using an 18 g introducer. Mean lesion volume produced with PERF (80°C for 90 seconds) and an 18 g diameter tip (215 mm3) is significantly larger than the respective one produced with MRF (169 mm3). Increasing lesioning time to 150 seconds significantly increases the volume (283 mm3). Using a 20 g tip produces the smallest lesions at 80°C for 90 seconds with either PERF or MRF, although a lesioning time of 150 seconds makes it significantly larger (207 mm3). Limitations: The study is ex vivo and therefore does not account for the dynamic effects of the anatomy and physiology of a living organism. Conclusions: The results indicate that the lesion produced with a cooled-RF system (17 g, 4 mm tip) is significantly larger than that produced with either of the other systems trialed (18 g or 20 g, 10 mm active tip protruding electrode or 16 g, 18 g, or 20 g monopolar electrode). Interestingly, a 16 g, 10 mm active tip monopolar electrode produced a larger lesion than the one produced with the 18 g protruding electrode. Key words: Radiofrequency, ablation, lesion shape, lesion size, cooled-RF, protruding electrode RF, monopolar RF.
Purpose: To assess the noninferiority of a single platelet-rich plasma (PRP) injection compared with hyaluronic acid (HA), to alleviate pain and enhance functional capacity in knee osteoarthritis, and identify biological characteristics of PRP that may affect their efficacy. Methods: Fifty-four patients with symptomatic knee osteoarthritis received a single injection of either PRP (26 patients) or HA (28 patients). They were assessed at baseline and at 1, 3, and 6 months. The primary endpoint was the change in Western Ontario and McMaster Universities Arthritis Index (WOMAC) score at 3 months, and secondary endpoints were responders' rate (improvement of at least 5 points or 40% of WOMAC total score at 3 months) of pain evaluation and patient's subjective satisfaction. Cell counts and the contents of vascular endothelial growth factor (VEGF), platelet-derived growth factor-AB (PDGF-AB), transforming growth factor beta 1 (TGF-β1) content of injected PRP were assessed to analyze their relationship with clinical outcome. Results: Both treatments proved their improvement in knee functional status and symptom relief, with a significant decrease observed at 1 month on all scores except for pain VAS in PRP group and WOMAC function score in the HA group. No difference between groups regarding WOMAC and VAS scores was observed. A higher percentage of responders was observed in the PRP group (72.7%) than in the HA group (45.8%) without significance (P = .064). The quantity of injected PDGF-AB and TGF-β1 correlated with the change in WOMAC scores at 3 months and was lower in responders than in nonresponders (P = .009 and P = .003, respectively). Conclusions: Current results indicated that a single injection of very pure PRP offers a significant clinical improvement in the management of knee osteoarthritis, equivalent to a single HA injection in this patient population. Moreover, a significant correlation between the doses of TGF-β1 and PDGF-AB and the worsening of WOMAC score 3 months after the procedure was found. Level of evidence: Level II, randomized double blind controlled trial.
Background: This study is a secondary analysis of 12-month follow-ups from two parallel, randomised controlled trials (RCT) in painful knee osteoarthritis patients. RCT1: Total knee replacement (TKR) followed by non-surgical treatment compared with non-surgical treatment. RCT2: Non-surgical treatment compared with usual care. The aims were to investigate 1) possible predictors of treatment outcome after TKR and non-surgical interventions at 12 months, 2) associations between pain intensity and pressure pain thresholds (PPTs) (pain sensitisation) at baseline and after 12 months, and 3) possible gender differences. Method: Each RCT included 100 patients. Pain intensities, PPTs, and number of painful sites were assessed at baseline and after 12 months. Results: In all groups pain improved and pain sensitisation decreased. In RCT1, the TKR group had the greatest improvements in pain. In RCT2 the non-surgical group had the greatest improvement, with no between-group differences in PPTs. Lower PPTs at baseline predicted higher pain after TKR. Baseline pain intensity and PPT levels were associated with the number of painful sites. Subjects with the highest pain and lowest PPTs at baseline showed the largest relative improvement in pain and sensitisation but were still experiencing highest absolute pain and lowest PPTs after 12 months (combined cohorts). Conclusion: Low PPTs at baseline predicted worse pain outcome after TKR, but did not predict outcome after non-surgical interventions. The number of painful sites was weakly associated with pain and PPTs, and the higher pain/lower PPTs, the higher pain/lower PPTs at 12 months with females showing the lowest PPT values. This article is protected by copyright. All rights reserved.
Aims: Meniscal allograft transplantation is undertaken to improve pain and function in patients with a symptomatic meniscal deficient knee compartment. While case series have shown improvements in patient reported outcome measures (PROMs), its efficacy has not been rigorously evaluated. This study aimed to compare PROMs in patients having meniscal transplantation with those having personalized physiotherapy at 12 months. Patients and methods: A single-centre assessor-blinded, comprehensive cohort study, incorporating a pilot randomized controlled trial (RCT) was performed on patients with a symptomatic compartment of the knee in which a (sub)total meniscectomy had previously been performed. They were randomized to be treated either with a meniscal allograft transplantation or personalized physiotherapy, and stratified for malalignment of the limb. They entered the preference groups if they were not willing to be randomized. The Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score and Lysholm score and complications were collected at baseline and at four, eight and 12 months following the interventions. Results: A total of 36 patients entered the study; 21 were randomized and 15 chose their treatments. Their mean age was 28 years (range 17 to 46). The outcomes were similar in the randomized and preference groups, allowing pooling of data. At 12 months, the KOOS4 composite score (mean difference 12, p = 0.03) and KOOS subscales of pain (mean difference 15, p = 0.02) and activities of daily living (mean difference 18, p = 0.005) were significantly superior in the meniscal transplantation group. Other PROMs also favoured this group without reaching statistical significance. There were five complications in the meniscal transplantation and one in the physiotherapy groups. Conclusion: This is the first study to compare meniscal allograft transplantation to non-operative treatment. The results provide the best quality evidence to date of the symptomatic benefits of meniscal allograft transplantation in the short term, but a multicentre RCT is required to investigate this question further. Cite this article: Bone Joint J 2018;100-B:56-63.
Background and Objectives. Genicular nerve radiofrequency ablation is an effective treatment for patients with chronic pain due to knee osteoarthritis; however, little is known about factors that predict procedure success. The current study evaluated the utility of genicular nerve blocks to predict the outcome of genicular nerve cooled radiofrequency ablation (cRFA) in patients with osteoarthritis. Methods. This randomized comparative trial included patients with chronic knee pain due to osteoarthritis. Participants were randomized to receive a genicular nerve block or no block prior to cRFA. Patients receiving a prognostic block that demonstrated �50% pain relief for six hours received cRFA. The primary outcome was the proportion of participants with �50% reduction in knee pain at sixmonths. Results. Twenty-nine participants (36 knees) had cRFA following a prognostic block, and 25 patients (35 knees) had cRFA without a block. Seventeen participants (58.6%) in the prognostic block group and 16 (64.0%) in the no block group had �50% pain relief at six months (P=0.34). A 15-point decrease in the Western Ontario and McMaster Universities Osteoarthritis Index at six months was present in 17 of 29 (55.2%) in the prognostic block group and 15 of 25 (60%) in the no block group (P=0.36). Conclusions. This study demonstrated clinically meaningful improvements in pain and physicalfunction up to six months following cRFA. A prognostic genicular nerve block using a local anesthetic volume of 1mL at each injection site and a threshold of�50% pain relief for subsequent cRFA eligibility did not improve the rate of treatment success.