Hip chronic pain: ultrasound guided ablation of anterior articular branches plus posterior neurolysis of the nerve to the quadratus femoris versus the alone anterior approach—a retrospective observational study

Abstract

Introduction

Chronic hip pain is a common painful condition in the elderly population. A mini invasive technique that is increasingly being considered for management of CHP is the percutaneous denervation of hip articular branches via radiofrequency ablation. We described a new ultrasound-guided technique based on the combination of 90° ultrasound-guided anterior radiofrequency ablation of the articular branches of femoral nerve, accessory obturator nerve and obturator nerve for anterior hip, combined with 90° ultrasound-guided ablation of the articular branches of the nerve of the quadratus femoris for posterior pericapsular neurolysis of the hip.

Material e methods

We retrospectively analyzed the medical records of patients from September 2022 to September 2023 treated for chronic hip pain in the ambulatory of Pain Management, identifying 22 patients who underwent ultrasound guided radiofrequency denervation of anterior hip articular branches alone (Group B); and 22 patients in which was also applied a radiofrequency denervation of the posterior articular branches, in addition to the anterior denervation (Group A). We analysed the pain intensity of both groups measured with numeric rating scale.

Result

The combined anterior plus posterior approach ensured that the results obtained were maintained 6 months after the procedure (T3) with excellent pain control and an average NRS of 1455 for group A. While for the group B, with the anterior approach alone, the NRS at six months showed an upward trend with an average NRS of 3818. The dual approach is more effective in pain relief at 6 months with a statistically significant difference in NRS values (p < 0.001).

Conclusion

This retrospective observational study highlighted the greater impact of the double approach (anterior plus posterior) in the denervation of the hip joint, compared to anterior neurolysis alone.

Introduction

Chronic hip pain (CHP) is a common painful condition in the elderly population; it is associated with pain, stiffness, muscles atrophy, mobility limitation and instability. Osteoarthritis (OA) represents the main cause of CHP [1, 2]. The treatment is based on the use of analgesic drugs, minimally invasive procedures such as intra-articular injection of hyaluronic acid, corticosteroids, PRP or steam cells. The invasive treatment is total hip arthroplasty (THA) [3, 4]. THA is one of the most common and successful types of orthopedic surgery, and future demands for THA is estimated to grow rapidly [5, 6]. In nationwide survey Nikolajsen e al found that, up to 28% had chronic ipsilateral hip pain at more than 1 year following the procedure and 12.1% of these patients had moderate to significant limitations of their daily activities secondary to the chronic hip pain [7]. A mini invasive technique that is increasingly being considered for management of CHP is the percutaneous denervation of hip articular branches via radiofrequency ablation (RFA) [4]. Currently the technique in most cases involves the use of fluoroscopy to identify the landmarks on which to perform denervation of the joint [8, 9]. A recent studies encouraged the use of ultrasound-guidance in order to improve safety and efficacy of the technique [10–12]. Furthermore, the most used approach is the anterior one with ablation of the articular branches of the femoral nerve (ABFN) and the articular branches of accessory obturator nerve (AON). [9] To improve analgesia and safety, we described a new ultrasound-guided technique based on the combination of 90° ultrasound-guided anterior radiofrequency ablation of the ABFN, AON and obturator nerve (ON) for anterior hip, combined with 90° ultrasound-guided ablation of the articular branches of the nerve of the quadratus femoris (NQF) for posterior pericapsular neurolysis of the hip. [13, 14]

This is a retrospective observational study aimed at comparing the effects of the combined ultrasound-guided hip denervation technique, comparing it with the classic ultrasound-guided anterior approach, analyzing the medical records of our patients. This research complies with the guidelines for human studies and was conducted ethically in accordance with the World Medical Studies involving human subjects. Written consent patients was obtained.

Clinically relevant anatomy

The anterior hip capsule received innervation from the Femoral nerve (FN), ON and the AON [15, 16]. Articular branches from the NQF supply the posterior hip. This is the anatomical basis of posterior hip pericapsular neurolysis. [13–18]

Methods

We retrospectively analyzed the medical records of patients from September 2022 to September 2023 treated for CHP in the ambulatory of Pain Management, identifying 22 patients who underwent ultrasound guided radiofrequency denervation of anterior hip articular branches alone (Group B); and 22 patients in which was also applied a radiofrequency denervation of the posterior articular branches, in addition to the anterior denervation (Group A). We analysed the pain intensity of both groups measured with numeric rating scale (NRS). [19] The pain intensity was measured before the procedure (baseline T0) and at 1 month (T1), 3 months (T2) and 6 months (T3) after the intervention.

For posterior approach the patient was placed in a prone position. A curved low-frequency ultrasound probe (2–5 MHz) was initially placed over the ilium and slide caudally until the greater sciatic foramen was visualized. From there, the probe was moved laterally along the piriformis until the greater trochanter was visualized. A 22 G, 100 mm needle radiofrequency cannula with thermocouple temperature sensor was then inserted with an in-plane approach, towards the plane between piriformis and the ischiofemoral ligament in a medial to lateral direction over the superolateral part of posterior capsule. This is also the location where the articular branch of NQF enters the posterior hip capsule. We started with a sensory stimulation during which the patient reported a tingling feeling, pain, or discomfort in the posterior region of the thigh. A motor stimulation was applied too, but without muscle contraction. Then we started the thermal radiofrequency ablation at 90° for one minute previously putting 1 ml of lidocaine avoiding pain feeling. Figure 1 Fig. 2

Fig. 1.

Ultrasound-guided ablation of the articular branches of the nerve of the quadratus femoris (NQF) for posterior pericapsular neurolysis of the hip. GT, great trochanter; N, needle

Fig. 2.

Needle position in Ultrasound-guided ablation of the articular branches of the nerve of the quadratus femoris (NQF) for posterior pericapsular neurolysis of the hip

In the anterior approach the first target were the ABFN. Initially using a curved low-frequency ultrasound probe (2–5 MHz), placed in a transverse plane, the anterior-inferior iliac spina was identified. Then turning the probe 45°, the ischiopubic eminence and the femoral artery were visualized. The needle was inserted, with an in-plane approach from lateral to medial direction in order to place the tip of the needle towards the inferior part of the femoral artery at six o’clock position, where the neural sensory articular branches of the femoral nerve are clustered much tighter than areas closer to the joint. We proceeded with a sensory stimulation during which the patient reported a tingling feeling, pain or discomfort in the antero-superior region of the thigh. A motor stimulation was applied too, but without quadriceps muscle contraction. Then we proceeded to thermal radiofrequency ablation at 90° for one minute previously putting 1 ml of lidocaine avoiding pain feeling. Figure 3 Fig. 4

Fig. 3.

Ultrasound-guided anterior radiofrequency ablation of the articular branches of Femoral nerve (ABFN). Star, ABFN; PT, Psoas tendon; FA, Femoral artery; AIIS, anterior inferior ischiatic spine; IPE, ileo-pubic eminence

Fig. 4.

Needle position in ultrasound-guided anterior radiofrequency ablation of the articular branches of Femoral nerve (ABFN), Accessory Obturator nerve AON and Obturator nerve (ON) for anterior hip

For sensory articular branches of Obturator Nerve, we put a curved low-frequency ultrasound probe (2–5 MHz), placed in a transverse plane, to identify the femoral head, neck and superomedial acetabulum. Then, moving the US probe medially we visualized the inferomedial acetabulum that was the target. Subsequently, the needle was inserted with an in-plane approach, to the lateral edge of the inferomedial acetabulum. We proceeded with a sensory stimulation during which the patient reported a tingling feeling (visible in the screen as a contraction around the nerve), pain or discomfort in the anteromedial region of the thigh. A motor stimulation was applied too, but without adductor muscles contraction. Then we proceeded to thermal radiofrequency ablation at 90° for one minute previously putting 1 ml of lidocaine avoiding pain feeling Figures 25.

Fig. 5.

Ultrasound-guided anterior radiofrequency ablation of the articular branches Obturatory nerve. Star, Position of the articular branches of Obturatory nerve near the infero-medial acetabulum that was the target

For sensory articular branches of AON, we put a curved low-frequency ultrasound probe (2–5 MHz), placed in a transverse plane, aligning the anterior-inferior iliac spina and Ileopubic Eminence (IPE). The tendon of ileopsoas muscle is shown as hyperechoic structure at the end of the muscle. Femoral artery is on the medial side of the muscle. The needle was then inserted with an in-plane approach, towards the IPE until to touch the bone. We proceeded with a sensory stimulation during which the patient reported a tingling feeling, pain or discomfort in the medial region of the thigh. A motor stimulation was applied too, but without adductor muscles contraction. Then we proceeded to thermal radiofrequency ablation at 90° for one minute previously putting 1 ml of lidocaine avoiding pain feeling. Figure 6 The entire procedure was completed in 35 min for Group A and in 50’ for group B.

Fig. 6.

Ultrasound-guided anterior radiofrequency ablation of the articular branches of the Accessory Obturatory nerve. FA, Femoral artery; IPE, ileo-pubic eminence; AON, position of the articular branches of the Accessory Obturatory nerve

No patient reported complications related to the procedure or during the follow-up period. No one reported muscle weakness or paresthesia. All patients were able to flex the limb and extend the leg, demonstrating the absence of muscle weakness or paresthesia in those areas innervated by nerve to quadratus femoris, femoral nerve, obturator nerve and accessory obturator nerve. Pain was measured using NRS. [19]

Statistical analysis

All variables were analysed, and it were reported as frequencies or means with standard deviation (SD) as they were categorial or numerical variables. Comparison between the two investigated groups (group A vs group B), were performed using Two-sample Wilcoxon rank-sum (Mann–Whitney) test or Chi Square test.

Repeated measures ANOVA (RM-ANOVA) was performed, with groups as between-subject factors and time series data as within-subject factors. Greenhouse-Gesseir correction was applied when sphericity was violated. Bonferroni method was used for multiple comparisons. All analysis were performed using STATA software, setting the significance level at alpha = 0.05.

Results

Forty-four patients treated for CHP was analyzed: 22 patients who underwent ultrasound guided radiofrequency denervation of anterior hip articular branches alone (Group B); and 22 patients in which was also applied a radiofrequency denervation of the posterior articular branches, in addition to the anterior denervation ( Group A). There were not differences between groups with respect age and sex, as reported in Table 1.

Table 1.

Demographics characteristics of patients

	GROUPS
Variables	A (N=22)	B (N=22)	p-value*
Age (years)	73.2 (8.7)	71.6 (8.8)	0.589
Sex
Female	14 (63.6%)	12 (54.5%)	0.540
Male	8 (36.4%)	10 (45.5%)

*Two-sample Wilcoxon rank-sum (Mann–Whitney) test or chi square

RM-ANOVA analysis indicated the significant effect of the time (F = 1001;p < 0.001), the scores were reduced in both groups. There was the significant effect of the type of the treatment, in fact the difference between groups was statistically significant (F = 22.8; p < 0.001). The interaction group*time was also significant (F = 35.9; p < 0.001).

As reported in Fig. 7 and Table 2, pain perceived at baseline (NRS T0) was on average 7 in both groups. Both approaches proved to be valid in significantly reducing pain in the first three months without differences. The combined anterior plus posterior approach ensured that the results obtained were maintained 6 months after the procedure (T3) with excellent pain control and an average NRS of 1455 for group A. While for the group B, with the anterior approach alone, the NRS at 6 months showed an upward trend with an average NRS of 3818. The dual approach is more effective in pain relief at six months with a statistically significant difference in NRS values (p < 0.001).

Fig. 7.

Graphic evaluation of the variation of the NRS over time

Table 2.

Numerical Rating Scores (mean) between groups over time

	Groups
	A Mean (SD)	B Mean (SD)	pBonferroni
NRS T0	7.136 (0.99)	7.136 (0.64)	1.000
NRS T1	0.273 (0.55)	0.409 (0.59)	1.000
NRS T2	0.864 (0.77)	1.318 (0.48)	0.668
NRS T3	1.455 (0.96)	3.818 (0.73)	< 0.001

Discussion

To confirm the safety and effectiveness of the use of ultrasound in pain therapy procedures in a recent randomized controlled trial Nisolle et al. demonstrated that the medial lumbar branch block under ultrasound-guidance is not inferior to the fluoroscopy guidance procedure in effectively alleviating pain arising from the facet joints. [20] Furthermore the use of ultrasound guidance allows us to reduce operating times and costs. The use of ultrasound guidance allows the operation to be performed not in the operating room with greater comfort for the patient and without exposure to ionizing radiation. The possibility of using colour Doppler during the procedure allows us to avoid injury to the arterial and venous vessels present in that district and last but not least, the ultrasound allows a better identification of myofascial bundles, nerves and arteries when compared to fluoroscopy. The only real limit to the use of ultrasound guidance is severe obesity in patients with BMI > 36 kg/m.². In these cases fluoroscopic guidance is recommended. [21]

Radiofrequency denervation today represents a effective and safe alternative in the treatment of chronic pain, such as in low back pain or in osteoarthritis of the knee with the denervation of the geniculate nerves. In these two cases there are many randomized controlled trial and meta-analyses that confirm their effectiveness. [22, 23] To date, and as highlighted in 2017 by Anuj Bhatia et al., no randomized controlled trial have been carried out on radiofrequency denervation of the hip joint. However they performed a review of the existing literature which highlighted the effectiveness of this procedure in the treatment of chronic hip joint pain [23]. In the study by Fishchenko et al., 46 patients underwent radiofrequency ablation of the articular branches of the femoral obturator nerves under fluoroscopic guidance. In our study, group B undergoing ultrasound-guided radiofrequency ablation achieved the same results in terms of pain reduction 6 months after the procedure. Based on these results there are no differences between the use of fluoroscopy or ultrasound guidance. the use of ultrasound guarantees greater safety for the patient, thanks to the possibility of directly visualizing the nervous and vascular structures [24]. There is currently no data in the literature to compare our new approach. In our experience the addition of denervation of the posterior portion of the hip joint capsule has an important role in reducing chronic pain.

The limitation of this study is the retrospective nature and the limited number of patients enrolled.

Conclusion

This retrospective observational study highlighted the greater impact of the double approach (anterior plus posterior) in the denervation of the hip joint, compared to anterior neurolysis alone. In group A, the double approach reduced the NRS by approximately 6 points six months after the intervention in patients with CHP.

Further and more structured study are necessary to assess these results.

Author contributions

All authors contributed to the study conception and design, material preparation, data collection and analysis.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Data availability

Not applicable.

Declarations

Conflict of interest

The authors have no relevant financial or non-financial interests to disclose.

Ethical approval

Not applicable.

Consent to participate

Not applicable.

Consent to publish

Not applicable.