ORIGINAL ARTICLE

Comparison of the Therapeutic Efficacy of TENS vs Ultrasound-guided Genicular Nerve Block in Patients with Knee OsteoarthritisIshita Dey1, Vasundhara Ghosal2, Ambar Konar3, Rajesh Pramanik4

Ab s t r Ac t Introduction: Osteoarthritis (OA) knee is a common disease of the aged population and one of the leading causes of disability. There are various treatment modalities to manage the pain in this condition including transcutaneous electrical nerve stimulation (TENS) and genicular nerve block (GNB).Aims and objectives: To assess and compare the effect of ultrasound-guided GNB and repeated daily TENS for 3 weeks in chronic knee pain in patients with OA knee.Materials and methods: The study is a randomized clinical trial done over duration of 18 months in the Department of Physical Medicine and Rehabilitation; IPGMER and SSKMH with a total sample size of 64 patients (32 in each group). Patients of age 40–80 years suffering from symptomatic primary OA knee with K/L score 3 and 4, poorly responding to conservative treatments and devoid of any exclusion criteria were included in the trial. After ethics committee clearance and obtaining informed consent, 64 patients were randomized into 2 treatment groups. Transcutaneous electrical nerve stimulation was applied for 3 weeks in the first group. In the second group, a US-guided GNB was done. Pain and knee function were assessed with visual acuity scale (VAS) and Western Ontario and McMaster Universities index at baseline, 1, and 3 months.Results: Statistically significant reduction in VAS and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) detected over time in both groups. WOMAC was significantly better in the GNB group than in TENS at 1-month follow-up.Conclusion: Both TENS and GNB have good clinical effects on knee OA with the superiority of GNB.Keywords: Genicular nerve, Knee pain, Osteoarthritis, Transcutaneous electrical nerve stimulation, Ultrasonography.Indian Journal of Physical Medicine & Rehabilitation (2020): 10.5005/jp-journals-10066-0073

In t r o d u c t I o n Osteoarthritis (OA) is a degenerative joint disease that initially involves the articular cartilage and later on the subchondral bone, synovial tissue, joint capsule, ligaments, and muscles that act on the joint.1 This can result in stiffness, swelling, and pain. Initial treatment of OA knee includes weight reduction, physical therapy, analgesics, and later on intra-articular steroid or visco-supplementation injections can be tried.2 When conservative treatment fails, total knee replacement (TKR) is traditionally offered but it has multiple perioperative morbidities.3 Additionally, many patients are not surgical candidates due to comorbidities and others simply do not want to undergo surgery.

In OA knee, management of pain is also very challenging. Non-steroidal anti-inflammatory drugs (NSAIDs) so commonly used have no long-term benefits and their use is limited due to well-known gastrointestinal, cardiovascular, and renal adverse effects. Intra-articular corticosteroids provide only short-term relief. The use of opioids also gives suboptimal pain reduction.4 Among physical modalities, transcutaneous electrical nerve stimulation (TENS) is most widely used for the management of OA knee pain.5,6 Recently, intervention on the genicular nerves has emerged as a promising treatment option.7,8 Aim of this procedure is to relieve pain by inhibiting the major nerve fibers that carry the pain sensation from knee joint capsule,9 one of the most important pain generators in OA knee.

re v I e w o f LI t e r At u r e Management of OA knee ranges from symptomatic relief, the arrest of the degenerative procedure, biomechanical correction as well as

lifestyle and ergonomic modification, and finally surgery. According to Altman et al., the goals of current treatment methods are to provide pain relief and to improve function and quality of life (QOL) in patients suffering from symptomatic OA knee.10 Transcutaneous electrical nerve stimulation and therapeutic exercises were described by the Philadelphia Panel as to be beneficial for pain control in knee OA.5 In 1991, Jensen et al. examined the beneficial

1Department of Physical Medicine and Rehabilitation, RG Kar Medical College and Hospital, Kolkata, West Bengal, India2,4Department of Physical Medicine and Rehabilitation, Institute of Postgraduate Medical Education and Research and Seth Sukhlal Karnani Memorial Hospital, Kolkata, West Bengal, India3Department of Physical Medicine and Rehabilitation, North 24 Pargana District Hospital, Barasat, West Bengal, IndiaCorresponding Author: Vasundhara Ghosal, Department of Physical Medicine and Rehabilitation, Institute of Postgraduate Medical Education and Research and Seth Sukhlal Karnani Memorial Hospital, Kolkata, West Bengal, India, Phone: +91 9874351897, e-mail: vasundharaghosal@gmail.comHow to cite this article: Dey I, Ghosal V, Konar A, et al. Comparison of the Therapeutic Efficacy of TENS vs Ultrasound-guided Genicular Nerve Block in Patients with Knee Osteoarthritis. Indian J Phys Med Rehab 2020;31(2):38–41.Source of support: NilConflict of interest: None

© Jaypee Brothers Medical Publishers. 2020 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Comparison of the Therapeutic Efficacy of TENS vs Ultrasound-guided Genicular Nerve Block

Indian Journal of Physical Medicine & Rehabilitation, Volume 31 Issue 2 (April–June 2020) 39

effect of conventional TENS (80 Hz, 150 seconds) in patients with OA knees.11 The accuracy of the ultrasound-guided genicular nerve block (GNB) was confirmed by Yasar et al. in their study in 2014.12 Multiple studies are recently available on the beneficial effects of genicular nerve neurotomy and symptomatic improvement in patients of OA knee.8,10,13 Superomedial (SM), inferomedial (IM), and superolateral (SL) genicular nerve branches have been targeted for intervention in previous studies as they are the main innervating articular branches and are adjacent to the periosteum connecting the bone, thus can be easily located.12,13

There is a paucity of literature comparing ultrasound-guided GNB with TENS in patients suffering from OA of the knee.

ob j e c t I v e s o f t h e st u dy • To assess the efficacy of ultrasound-guided GNB and repeated

daily TENS for 3 weeks in chronic knee pain in patients with OA knee.

• To compare their effectiveness in pain, stiffness, and function in patients with OA knee.

MAt e r I A L s A n d Me t h o d s Study DesignThis study is a randomized controlled trial where two treatment groups served as a control for each other. But, single blinding was not possible as one noninvasive procedure was compared with an invasive procedure. Computer-generated randomization was done until the two treatment groups got an equal number of patients.

Study AreaDepartment of Physical Medicine and Rehabilitation, Institute of Post Graduate Medical Education and Research, Seth Sukhlal Karnani Memorial Hospital, (IPGMER; SSKMH), Kolkata was chosen as the study area.

Study PopulationThis study recruited the patients attending the outpatient services of the Department of Physical Medicine and Rehabilitation, Institute of Post Graduate Medical Education and Research, Kolkata with symptomatic primary OA knee who also fulfilled the study inclusion criteria.

Study Period12 months (June 2016 to June 2017).

Sample SizeThe sample size for this study was calculated based on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) as the primary outcome measure at 3 months. Total 64 patients were included in this study, 32 each in the TENS group and GNB group, respectively.

Inclusion Criteria

• Primary OA knee.• Radiologic K/L (Kellgren-Lawrence Grading Scale) score: 3 and 4.• Age: 40–80 years.• Poorly responding to initial treatments.• Patients unwilling or contraindicated for surgical management.• Visual acuity scale (VAS) >5.

Exclusion Criteria

• Prior knee surgery.• Secondary OA.• Associated sciatic or other neuropathic pain.• Intra-articular corticosteroid or visco-supplementation injection

within the last 3 months.• The presence of an unstable medical condition or a known

uncontrolled systemic disease, including cancer, diabetes, coagulopathy, major depression, and schizophrenia.

• Patients with contraindications of steroid injections, i.e., overlying soft tissue sepsis, bacteremia, anatomic inaccessibility, and uncooperative patient.

Study Tools

• VAS scale.• WOMAC index (3.1).

Materials

• Sphygmomanometer and stethoscope.• Samsung Medison PT60A Diagnostic Ultrasound system.• Medison LN5-12 transducer.• TENS machine.• Disposable syringe and needles.• 22-gauge spinocaine needle.• Sterile gloves and gauze pieces.• Swab holding forceps.• Povidone-iodine, 95% alcohol and Savlon.• Injection depot methylprednisolone acetate (80 mg/2 mL).• Inj. lignocaine (2%).• Inj. bupivacaine (0.25%).• Band-aid.

MethodologyEthical approval was obtained from the institutional ethics committee and individual informed consent was taken from every recruited patient. All the subjects recruited in our study underwent some baseline routine blood investigation. The total study population (n = 64) was divided into two groups (32 in each group) randomly. Before starting treatment, basic information like age, sex, and duration of disease were noted and baseline VAS and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were calculated. A short course of acetaminophen tablet, lifestyle modification, and therapeutic exercise regimen was prescribed and followed.

The first group of patients received TENS around the knee with 100 Hz frequency and 200-ms pulse. Two pairs of rubber electrodes were placed over the acupuncture points of the knee. The duration was set to 40 minutes. This was procedure was repeated daily for 3 weeks.

In the second group, the GNB was performed in the operation theater with appropriate monitoring and aseptic precautions. Samsung Medison PT60A Diagnostic Ultrasound system and Medison LN5-12 transducer were used for identification of the sono-anatomic landmarks. Superolateral, SM, and IM genicular nerves were located. The SL genicular nerve was located at the junction of the lateral femoral shaft and the lateral femoral condyle. The SM was identified about 1 cm anterior to the adductor

Comparison of the Therapeutic Efficacy of TENS vs Ultrasound-guided Genicular Nerve Block

Indian Journal of Physical Medicine & Rehabilitation, Volume 31 Issue 2 (April–June 2020)40

tubercle, accompanied by the SM genicular vessels after keeping the transducer in a sagittal plane over medial femoral condyle and gradually translating it proximally (Fig. 1). Inferomedial genicular nerve is identified keeping the transducer horizontally near the medial tibial epicondyle at the midpoint between the medial epicondyle and the tibial insertion of the medial collateral ligament. A 22-gauge spinocaine needle was introduced in parallel to the long axis of the transducer. Each block was done with 2 mL solution from a standard mixture of Inj. lignocaine 2% 3 mL + Inj. 0.25% bupivacaine 2 mL + depot methylprednisolone 40 mg/mL 1 mL.

Assessment of VAS and WOMAC was done at baseline and 1 month and 3 months after GNB and completion of TENS therapy. At the end of the study, all the demographic and other numerical data were collected and tabulated. The data were analyzed by standard statistical tools.

re s u Lts A n d An A Lys I s Data were summarized by routine descriptive statistics. Software used were Statistica version 6 (Tulsa, Oklahoma: StatSoft Inc., 2001) and GraphPad Prism version 5 (San Diego, California: GraphPad Software Inc., 2007). Data were compared between baseline and follow-up assessments and in-between the two groups by repeated measures analysis of variants (ANOVA) and Student’s unpaired t-test,

respectively, for numerical variables and by Fisher’s exact test for categorical variables. The analysis was two-tailed and p < 0.05 was considered statistically significant.

All numerical variables were found to be normally distributed by Kolmogorov–Smirnoff goodness-of-fit. The mean age of patients in TENS group (n = 32) was around 54.16 (±7.582) years and in GNB group (n = 32) was 55.53 (±6.877) years. In both groups, female preponderance was found (59%). Fisher’s exact test showed no statistically significant difference (p value 1.000) in the proportion of males and females between the two groups.

Comparison of changes over time within respective groups was done by repeated measures ANOVA. It shows progressive improvement in both the parameters (VAS for pain and WOMAC) in both the treatment groups. Tukey’s multiple comparison test also shows significant improvement in every follow-up.

As shown in Table 1, a comparison of the numerical variable VAS for pain between both the groups by Student’s unpaired “t” test shows, after continuous 3 weeks of daily TENS therapy, knee pain improved from a mean VAS of 7.25 (±0.916) at baseline to 3.56 (±1.045) at the end of 1 month. Whereas, with a single sitting of GNB, the mean VAS improved from a baseline value of 7.31 (±0.965) to 2.97 (±0.822) at the end of 1 month. Thus, GNB shows a significantly better result (p < 0.05) in improving knee pain than TENS therapy at 1 month. Although at the end of 3 months, the VAS in both the groups again becomes comparable (p = 0.117).

Knee stiffness and function were measured through Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). According to Table 2, a comparison of the numerical variable WOMAC between both the groups by Student’s unpaired “t” test shows, in the TENS group, WOMAC improved from a mean of 47.13 (±6.009) at baseline to 27.34 (±5.773) at the end of 1 month. In the GNB group (group II), the mean WOMAC improved from a baseline value of 46.59 (±5.758) to 24.34 (±4.715) at the end of 1 month. Thus, similar to pain, GNB shows significant better result (p < 0.05) in improving knee stiffness and function than TENS therapy at 1 month. At the end of 3 months, the WOMAC in both the groups again becomes comparable (p = 0.728).

dI s c u s s I o n This randomized control study was done at the Department of Physical Medicine and Rehabilitation, Institute of Post Graduate Medical Education and Research; Seth Sukhlal Karnani Memorial Hospital (IPGMER; SSKM Hospital), Kolkata, West Bengal investigated Fig. 1: Locating the superomedial genicular nerve by ultrasound

Table 1: Comparison of VAS for pain between TENS and GNB—Student’s unpaired “t” test

Mean group I Mean group II

p

Std. dev. Std. dev.

TENS GNB TENS GNBVAS_B 7.25 7.31 0.791 0.916 0.965VAS_1m 3.56 2.97 0.014 1.045 0.822VAS_3m 2.51 1.89 0.117 0.837 0.734

Table 2: Comparison of WOMAC between TENS and GNB—Student’s unpaired “t” test

Mean group I Mean group II

p

Std. dev. Std. dev.

TENS GNB TENS GNBWOMAC_B 47.13 46.59 0.719 6.009 5.758WOMAC_1m 27.34 24.34 0.026 5.773 4.715WOMAC_3m 16.25 14.25 0.728 2.851 2.874

Comparison of the Therapeutic Efficacy of TENS vs Ultrasound-guided Genicular Nerve Block

Indian Journal of Physical Medicine & Rehabilitation, Volume 31 Issue 2 (April–June 2020) 41

and compared the effect of TENS and US-guided GNB on OA-related knee pain and knee functions. All numerical variables were found to be normally distributed by Kolmogorov–Smirnoff goodness-of-fit. The patients in both groups had significant pain relief and improvement in knee functions throughout a follow-up period of 3 months. As we found in the TENS group, Paker et al. also found in their study with daily therapy of high-frequency TENS, there was significant (p < 0.001) improvement of both VAS and WOMAC over time.14 As in the study by Kesikburun et al., we also found that there is a significant improvement of VAS and WOMAC after GNB under USG guidance over 1 and 3 months, although they used radiofrequency ablative block.15 In this study, there is a statistically significant improvement difference at 1 month in knee pain, stiffness, and function with the GNB group being superior to the TENS group.

However, like other studies, our study has some limitations. Both the study parameters were subjective. Knee joint range of motion was not taken into account. Long-term follow-up could not be done.

co n c Lu s I o n • An overall outcome with both TENS and GNB in patients with

primary OA knee was quite statistically effective with a p value < 0.001 at the improvement in the study parameters of VAS for pain and WOMAC.

• There was a statistically significant improvement difference at 1 month with GNB being superior.

• Although at 3 months the VAS and WOMAC in both the groups again become comparable.

• So, it can be concluded that GNB is a better choice than TENS in the short-term and comparable in the long-term and both add to the OA knee rehabilitation program significantly.

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