Keywords
chronic pain - hip - osteoarthritis - hip - pulsed radiofrequency treatment
Palavras-chave
dor crônica - osteoartrite do quadril - quadril - tratamento por radiofrequência pulsada
Introduction
Populational aging and the increased physical demand in sports and work activities
result in a considerable increase in hip osteoarthritis (OA) prevalence. This prevalence
increases with age and, after 85 years old, one in four subjects has symptomatic hip
OA. Populational studies report a range of hip OA incidence probably due to clinical
and radiological dissociation. As such, chronic pain, stiffness, limited range of
motion, and instability are significant issues.[1]
The estimated prevalence of chronic hip pain in subjects aged over 45 is 7% in men
and 10% in women.[2] The quality of life (QoL) of these patients has a direct association with pain duration
and the need for prolonged searches for conservative strategies for pain relief, such
as physical therapy, nonsteroidal antiinflammatory drugs, opioids, and intraarticular
corticosteroid injections. These methods often provide partial and scarce symptomatic
relief.[3]
Several intra- and extraarticular pain sources are primary focus for hip pain, hindering
their differentiation. As such, radiofrequency (RF) and intraarticular injections
help to elucidate the pain source. Although the literature remains controversial,
RF use has been increasing as an alternate treatment for joint pain when it is refractory
to other available conservative methods, and in cases with surgical contraindication.[4]
[5]
Anatomical models showed that the sensory anatomy innervating the hip joint consists
of capsular branches of the femoral and obturator nerves, which are the major target
points for RF neuromodulation guided by fluoroscopic imaging in the anteroposterior
(AP) pelvis.[1]
The Tönnis classification is among the best-known and most widely used worldwide for
hip OA assessment. The study of a simple AP radiograph of the pelvis is enough for
this classification, which initially described three progressive degrees of joint
degeneration. In 1999, grade 0 was added, corresponding to subjects without the disease.
Type I describes patients with mild OA, minimal joint space narrowing, increased sclerosis,
and absent or minimal loss of sphericity of the femoral head. Type II demonstrates
moderate OA with small cysts, moderate joint space narrowing, and moderate loss of
head sphericity. Type III describes patients with advanced disease, which includes
severe OA with large cysts, severe joint space narrowing, severe loss of head sphericity,
and avascular necrosis.[6]
The main objective of this study was to evaluate the improvement in the QoL of patients
with hip OA who underwent PRF immediately, 2, 4, and 6 months after the procedure
using the short form-36 (SF-36) questionnaire. The second objective was to establish
a protocol for performing RF in the hospital for pain relief in patients on the waiting
list for surgery.
Materials and Methods
This observational, noncontrolled study occurred in our hospital from May to September
2022. We selected two senior hip surgeons from the same hip surgery group to conduct
the study. One nurse performed the initial assessment of the QoL of all patients before
the procedure, using the SF-36 questionnaire. All patients signed an informed consent
form (ICF) and the Ethics Committee, affiliated with Plataforma Brasil, approved the
study under opinion number 6.145.444 and CAAE number 69626023.1.0000.5273.
Patients
We initially selected 30 patients, from both genders, with hip OA in the total hip
arthroplasty (THA) waiting list. The inclusion criteria were patients over 50-years-old,
presenting the primary disease in the hip, and on the waiting list from 1 to 3 years.
We excluded patients under 50-years-old, with secondary hip OA, previous surgeries
on the affected hip, who underwent anesthetic infiltration less than 6-months, and
on the waiting list for less than 1 and more than 3 years.
Classification
A resident physician in Orthopedics and Traumatology at the same hospital studied
all hips to determine their Tönnis classification ([Table 1]) using the MDICON imaging software.
Table 1
Tönnis classification
|
Classification
|
Description
|
|
0
|
No hip OA signs.
|
|
I
|
- Mild OA.
- Minimal joint space narrowing and mild sclerosis.
- Absent or minimal loss of head sphericity.
|
|
II
|
- Moderate OA.
- Moderate joint space narrowing with small cysts.
- Moderate loss of head sphericity.
|
|
III
|
- Severe OA.
- Severe joint space narrowing with big cysts.
- Severe head deformity.
|
Abbreviation: OA, osteoarthritis.
Note: Adapted from Tönnis and Heinecke 1999.[5]
Pulsed Radiofrequency
Each surgeon would perform 15 RF procedures randomly. However, we only performed 13
procedures, due to the unsatisfactory partial outcomes, as some patients developed
worsening pain. Pulsed radiofrequency (PRF) uses a generator with 45 V amplitude and
a duration of 2 times per second. The generator modifies parameters in real-time to
reach the desired local temperature. In this method, the maximum temperature was 42°
Celsius without causing irreversible tissue damage or motor fiber involvement.
Procedure
All patients were taken to the surgical center and underwent light sedation throughout
the procedure and local anesthesia with 2% lidocaine in the affected hip. We used
two PRF tips from SOLIEVO (Sollievo Medicina Especializada, São Caetano do Sul, SP,
Brazil) for each subject. We inserted one tip into the sensory branches of the obturator
nerve, immediately inferior to the teardrop, and one tip into the sensory branches
of the femoral nerve, inferomedial to the anterior inferior iliac spine (AIIS). These
anatomical parameters were obtained through an AP fluoroscopic image of the hip ([Fig. 1]). After tip I al of methylprednisolone at 20 mg and ropivacaine 1% into each cannula
and applied a compressive dressing.
Fig. 1 (1) Femoral nerve (2) Obturator nerve. Source: Fluoroscopic imaging from the hospital.
Short Form-36
The SF-36 is a widely used QoL measure developed in the 1980s in the USA. The questionnaire
has 11 questions and 36 items, including 8 components (domains or dimensions) representing
functional capacity (10 items), physical aspects (4 items), pain (2 items), general
health status (5 items), vitality (4 items), social aspects (2 items), emotional aspects
(3 items), mental health (5 items), and one question comparing patients' perception
of their current health now and 1-year prior.[7]
[8]
Statistical Analysis
The values of each SF-36 domain were discrete and ranged from 0 to 100. Additionally,
the data presented a nonnormal distribution according to the Shapiro-Wilk test. Thus,
values were reported as median (interquartile range [IQR]), and the comparison between
pre- and post-PRF values used the Wilcoxon signed-rank test, and the Spearman rank
correlation coefficient determined associations between changes in each domain.
Results
Our results include only 13 of the 30 previously selected patients. Per the Tönnis
classification, eight subjects were type III, four were II, and one patient was type
I. All SF-36 assessments pre-PRF occurred the day of or before the procedure, while
for post-PRF the assessments occurred within 49 days, with the shortest and longest
intervals being 25 and 96 days, respectively.
[Table 2] shows the pain, general health status, social aspects, and mental health domain
values. We observed pain improvement in only 6 patients (46%), maintenance of the
pre-PRF state in 5 (38%), and worsening in 2 (15%). The general health status improved
in nine patients (69%), remained the same in 1 (8%), and worsened in 3 patients (23%).
Social aspects improved in 8 patients (62%), remained the same in 2 (15%), and worsened
in three (23%). Mental health improved in only 3 patients (23%), remained stable in
1 (8%), and worsened in 9 (69%). [Fig. 2] shows the individual variation in these domains.
Fig. 2 Variation in the domains assessed before and after pulsed radiofrequency. The group
values are presented by boxplots and the individual values by lines. The green lines
indicate improvement in the domain, orange indicate worsening, and gray indicate value
maintenance. Abbreviation: PRF, pulsed radiofrequency.
Table 2
Quality of life domains
|
Pre-PRF
|
Post-PRF
|
p-value
|
|
Pain
|
20 (21)
|
20 (31)
|
0.057
|
|
General health status
|
37 (28)
|
52 (18)
|
0.168
|
|
Social aspects
|
25 (25)
|
50 (62)
|
0.053
|
|
Mental health
|
48 (40)
|
44 (44)
|
0.169
|
Abbreviations: PRF, pulsed radiofrequency; p, p-value of the Wilcoxon signed-rank test.
We did not observe any correlation between variations in the pain, general health
status, and mental health domains ([Fig. 3]). We detected a borderline value in the statistical correlation test between variations
in pain and social aspects domains (p = 0.056).
Fig. 3 Scatter diagram of variations in the domains evaluated. Each point indicates a subject
and the dotted reference lines indicate the maintenance of values before and after
pulsed radiofrequency. Points located in the upper right quadrant indicate subjects
with simultaneous improvement in both domains, while points located in the lower left
quadrant indicate simultaneous worsening.
We interrupted the study due to the lack of partial beneficial results for patients
after performing 43.3% of PRF procedures.
Discussion
According to Giaccari et al.,[10] OA is the most prevalent joint disorder in the world and one of the main causes
of morbidity and functional disability. Hip OA is its second most common form. In
2019, OA prevalence in the last 10 years increased by 113.25%, going from 247.51 million
affected people in 1990 to 527.81 million in 2019. Thus, the literature reported that
health service costs for this condition represent 1 to 2.5% of the gross national
product of developed countries. This value must increase 4-fold by 2030.[11]
In the last 10 years, the waiting time for THA in our hospital from entering the list
until surgery is 3.1 years. These patients with chronic pain often overuse analgesic
and antiinflammatory medications and receive successive intraarticular steroid injections
with limited action. Considering the current reality in our hospital, we envisioned
PRF as a potential alternative and effective method for improving pain in these patients
and, as a result, their QoL.
Although RF is commonly used for chronic musculoskeletal pain,[10] the literature regarding PRF in patients with hip OA is scarce. In 2017, Short et
al.[1] and Bhatia et al.[3] reviewed 14 articles and demonstrated the great potential for reducing secondary
pain in up to 3 years, in addition to improving walking, using RF on the sensory innervation
of the hip (obturator, accessory obturator, and femoral nerves). Complications of
the procedure are rare and involve vascular injury, neuritis, hematoma formation,
and inadvertent ablation of motor branches of the obturator and femoral nerves.
The great advantage of PRF is the neuromodulation effects of the local electric field
by altering synaptic transmission and, consequently, less damage to local tissues
and less pain due to deafferentation.[12] Cooled RF (CFR) is similar to PRF but cooled with water through a probe, reaching
60°C. It can generate a neuronal lesion of a larger area, but its cost can be almost
two-fold higher than PRF.[13]
In another study published in 2015, 15 patients with mild-to-moderate hip OA, Tönnis
types I and II, underwent PRF and were compared with 14 patients who did not undergo
the procedure and received conservative treatment with paracetamol, nonsteroidal antiinflammatory
drugs (NSAIDs), and opioids. Patient assessment for pain and hip function used the
visual analog scale (VAS) and the Oxford hip score (OHS), and the subjects received
pain medications before the procedure and at 1, 4, and 12 weeks after. The VAS and
OHS scores showed a significant improvement in pain and hip function among PRF patients
in all weeks evaluated. These patients also used fewer analgesics after the procedure.[14]
This study had some limitations. It is known that cooled RF tips can achieve neuromodulation
diameters greater than PRF tips. However, due to their high cost, they could not be
used. Since 61.5% of the hips were Tönnis type III, presenting severe degeneration,
we strongly believe that PRF has no function in them. Further studies with less degenerated
hips would be of great value for its validation as an alternative treatment for hip
OA.
Conclusion
This study had to be interrupted with only 43.3% of the patients scheduled to undergo
PRF, due to the discouraging partial outcomes. Therefore, we must question whether
the investment in this technique, considered very expensive, is worthwhile and effective
in improving QoL of patients with hip OA.
Bibliographical Record
Rafaela Reis Torrealba, Phercyles Veiga-Santos, Maria Isabella Cruz de Castro, Lourenço
Peixoto, Marcelo Felipe Almeida, Conrado Torres Laett. Pain Evaluation after Pulsed
Radiofrequency in Patients with Osteoarthritis of the Hip. Rev Bras Ortop (Sao Paulo)
2025; 60: s00441800937.
DOI: 10.1055/s-0044-1800937
