A Retrospective Single-center Cohort Study on Patients With Chronic Knee Pain Treated With Conventional Radiofrequency of the Genicular Nerves
Conditions: Chronic Knee Pain
Sponsor: Ziekenhuis Oost-Limburg

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RECORGEN trial - version 1 - 19/6/2020 
 
 
 
 
 
 
PROTOCOL 
 
A retrospective single-center cohort study on patients with 
chronic knee pain treated with conventional radiofrequency of 
the genicular nerves.  
(Recorgen trial) 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Site Investigator: 
This study is organized by the Department of Chronic pain of the Hospital of Oost-
Limburg (Ziekenhuis Oost-Limburg ), Campus Sint-Barbara.  
It will be coordinated by Prof. Dr. Van Zundert and Dr. Vanneste. 
TITLE:  A retrospective single-center cohort study on patients with chronic knee pain treated 
with conventional radiofrequency of the genicular nerves. 
Protocol ID  
NCT04234984 
Version 
1 
Date  
19-6-2020 
Acronym 
RECORGEN 
Coordinating 
investigator 
/ 
project 
leader  
Prof. dr. Jan van Zundert, 
Anesthesiologist  
Department of Anesthesiology / Pain 
Medicine,  
Hospital Oost - Limburg, Genk, 
Belgium.  
+32(0)89325254  
Department of Pain Medicine,  
Maastricht University Medical Centre 
(MUMC+),  
Maastricht, the Netherlands.  
Principal investigator(s)  
- Drs. Thibaut Vanneste, 
Anesthesiologist  
Department of Anesthesiology / Pain 
Medicine,  
Hospital Oost - Limburg, Genk, 
Belgium.  
+32(0)89325316  
- Dr. Amy Belba 
Assistant in Anesthesiology   
Department of Anesthesiology / Pain 
Medicine,  
Hospital Oost - Limburg, Genk, 
Belgium.  
+32(0)487482763 
Sponsor  
ZOL Genk 
 
 
 
 
 
 

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TABLE OF CONTENTS 
Abbreviations and Definitions of Terms .......................................................................... 4 
Abstract.............................................................................................................................. 5 
Protocol Synopsis ............................................................................................................. 6 
1 BACKGROUND INFORMATION AND RATIONALE………………………………………7 
2 STUDY DESIGN………………………………………………………………………………...8 
     2.1 Study design      
     2.2 Questionaire 
3   STUDY SETTING AND POPULATION .......................................................................... 9 
  
     3.1 Study setting 
  
     3.2 Population 
  
             3.2.1 Inclusion criteria 
  
             3.2.2 Exclusion criteria 
4 STUDY OBJECTIVES ................................................................................................... 9 
 
4.1 Primary objective 
 
4.2 Secondary objectives  
5    STUDY ENDPOINDS………………………………………………………………………….10 
6    TIME SCHEDULE...........................................................................................................10 
7    STATISTICAL CONSIDERATIONS............................................................................. 11 
8  INFORMED CONSENT……………………………………………………………………….11 
9   REFERENCES ............................................................................................................. 11 
Appendix .......................................................................................................................... 13 
 

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LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
 
AE 
 
Adverse Event 
 
 
GPE 
 
Global Perceived Effect 
 
IC 
 
Informed Consent 
 
IL 
    
Inferior Lateral 
IM                    Inferior Medial  
NRS 
 
Numeric Rating Scale 
 
OKS   
Oxford Knee Score  
PPSP              Persistent Post-Surgical Pain  
RFA    
Radiofrequency Ablation 
SL 
 
Superior Lateral  
SM 
 
Superior Medial 
ZOL   
Ziekenhuis Oost-Limburg 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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ABSTRACT 
Context: Management of chronic knee pain remains a challenge to the treating physician. 
Chronic knee pain can be the consequence of osteoarthritis but also of persistent post-
surgical knee pain (PPSP). Conservative and surgical treatments may not always be the 
optimal solution in this diverse population, leading to a need for alternative treatment 
methods. A radiofrequency treatment of the genicular nerves is a not yet established but 
promising technique. It employs heat and an electrical field to target sensory knee nerve 
fibers in order to block them and alleviate chronic knee pain. This procedure is minimal 
invasive and has few adverse events. For these reasons it can be advantageous and fulfilling 
the unmet needs of these chronic knee pain patients warranting further research of its 
efficacy.  
Objectives: This project has as primary objective the evaluation of treatment success of a 
conventional radiofrequency treatment of the genicular nerves in patients diagnosed with 
chronic knee pain due to osteoarthritis of the knee or PPSP at six weeks post treatment. 
Secondary objectives are evaluation of treatment effect at a third time point at the end of the 
inclusion period, subgroup analysis of treatment success based on indication to treatment, 
evaluation of subjective functional improvement and change in analgesics, estimation of the 
duration of effect of the treatment and adverse events. 
Study Design: This study is a retrospective single-center cohort. 
Setting/Participants: This study includes all patients treated with radiofrequency ablation in 
the multidisciplinary chronic pain center in Ziekenhuis Oost-Limburg, Campus Sint-Barbara 
between 1 September 2017 and 30 June 2020 with exclusion of patients with chronic 
widespread pain. 
Main study endpoints: The main study outcome is the proportion of patients with a global 
perceived effect of at least 50% at 6 weeks post intervention. Secondary outcomes include 
reduction in pain intensity, measured by Numeric Rating Scale (NRS) at six weeks and at a 
third time point, global perceived effect at a third time point, subjective change in physical 
functioning, duration effect of the treatment, use of strong opioids, and adverse events.  
 
 
 
 
 
 
 
 

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PROTOCOL SYNOPSIS 
Study Title 
A retrospective single-center cohort study on patients with chronic 
knee pain treated with conventional radiofrequency of the genicular 
nerves. 
Funder 
ZOL Genk 
Study Objectives 
Primary objective 
• 
To 
evaluate 
treatment 
success 
of 
the 
conventional 
radiofrequency ablation at week 6 
Secondary objective 
• 
Evaluation of treatment effect at a third time point at the end of 
the inclusion period 
• 
Subgroup analysis of treatment success based on indication to 
treatment 
• 
Evaluation of subjective functional improvement 
• 
Evaluation of change in analgesics 
• 
Estimation of the duration of effect of the treatment 
• 
Adverse events  
Study Design 
Retrospective single-center cohort study 
Subject Population 
Key criteria for 
Inclusion and 
Exclusion: 
Inclusion Criteria 
1. All patients with chronic knee pain who qualify for a 
conventional RF treatment of the genicular nerves  
Exclusion Criteria 
1. Refusal to participate  
2. A negative diagnostic block with lidocaine 2% 1 ml of the 
three genicular nerves defined as less than 50% pain 
reduction 
3. Chronic widespread pain 
Time  
Patients treated with conventional RF treatment between 1 
September 2017 and 30 June 2020. 
Study endpoints  
1. Primary endpoint:   
- 
Proportion of patients with treatment success at 6 weeks 
defined as GPE of ≥ 50% compared to baseline. 
2. Secondary endpoints: 
- 
Proportion of patients with treatment success at third time 
point defined as GPE of ≥ 50% compared to baseline. 
- 
NRS reduction at week 6 and at the third time point 
- 
Subjective physical functioning at week 6 and at the third 
time point 
- 
Duration effect of the treatment defined as period with a 
GPE of ≥ 50% 
- 
Change in strong opioid use at week 6 and at the third time 
point 
- 
Safety: number/type of adverse events 
 

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1. BACKGROUND INFORMATION AND RATIONALE 
Chronic knee pain is one of the most common disabling joint disorders in the global 
population.(1) Chronic knee pain can be the consequence of osteoarthritis but also of 
persistent post-surgical knee pain (PPSP). Osteoarthritis is an active degenerative disease 
that involves cartilage, subchondral bone and new bone formation leading to a considerable 
number of patients suffering from disabling symptoms such as chronic pain, stiffness and 
loss of function. The lifetime risk of developing symptomatic knee osteoarthritis is estimated 
to be ~45% based upon Johnston County Osteoarthritis Project data.(2) 
Treatment strategies for chronic knee pain condition can be divided into surgical and non-
surgical. When a conservative treatment fails to treat the symptoms, surgical techniques 
come to rescue. Total knee arthroplasty or an artificial replacement of the knee is the 
treatment of choice in multiple clinical situations of osteoarthritis. Despite being a successful 
treatment, comorbidities frequently hinder its application. Secondly, artificial joint 
replacement has unfortunately a limited longevity, and pain or discomfort after total knee 
replacement is frequent. (3-5) The percentage of patients that continues to report clinically 
significant pain and/or dissatisfaction after total knee arthroplasty mounts up to 19%-20%. (6-
8) Residual pain has most commonly been associated with patellofemoral disorders, locating 
this pain largely in the anterior knee. (9) Due to this number of pitfalls a growing number of 
patients remain optionless facing disability, decrease in quality of life, extensive opioid 
consumption and/or polypharmacy. The groups of patients suffering from chronic knee pain 
including patients with comorbidities, non-geriatric patients and surgically treated patients 
with remaining knee pain have since the last decade been considered as potential 
candidates for treatment with radiofrequency ablation.  
Radiofrequency treatment is a novel technique implemented on knee pain. This method 
targets the sensory innervation of the knee, leading to a decrease in the transmission of pain 
signals. The knee nerves presently targeted are the genicular nerves which are branches of 
the femoral, saphenous, obturator, common peroneal, tibial and sciatic nerve. This technique 
has little contraindications and few reported adverse events. As such it is a potential 
promising solution to persistent knee pain.  
The first described conventional radiofrequency ablation of the genicular nerves is presented 
by Choi and colleagues in 2011. (10) In this double blind randomized trial patients showed 
significant improvement in pain and functionality scores in comparison with placebo. Since 
this first positive report, multiple investigations have explored and expanded the use of 
radiofrequency ablation towards pulsed radiofrequency and cooled radiofrequency treatment 
as alternatives to the conventional ablation. (11-13)   
In the present retrospective cohort study we will analyze patients treated with this novel 
technique in our chronic pain center. The main aim of this study is to determine treatment 
success of radiofrequency ablation on patients with chronic knee pain. Furthermore, we aim 
to gain a better insight in demographics, indications, referring physicians, complications and 
adverse events that might be beneficial for organizing care for chronic knee pain patients. 
 
 

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2. STUDY DESIGN 
2.1 Study design  
 
This study is designed as a retrospective longitudinal cohort study of patients treated with a 
radiofrequency treatment of the genicular nerves in a single-center (ZOL, Genk) between 1 
September 2017 and 30 June 2020. Each knee will be considered as a unique observation, 
and bilateral procedures were assessed specific to each knee treated. Data retrieved from 
the patient files will be collected at baseline, 6 weeks post-intervention and telephonically at a 
third time point which ranges from 6 weeks to 3 years after the procedure. The following 
demographic and clinical data will be collected at baseline: patient age, sex, NRS score, 
length of symptom duration, indication for the procedure, use of strong opioids, history of 
previous knee surgery and the referring physician. Strong opioid analgesics are defined as 
all opioids excluding tramadol and codeine.  
Data collected at 6 weeks post-intervention will include: NRS, GPE, adverse events, and 
concomitant use of strong opioids.  
Patient’s data will be collected at a third time point. Written informed consent will be obtained 
by mail prior to contact by phone. After receiving informed consent, patients will be contacted 
by telephone and data will be gathered on the same variables as at 6 weeks post-
intervention and on subjective functional outcome. 
 
2.2 Questionnaire 
At the third time point patients will be contacted by phone, after receiving written informed 
consent by mail. The study and its rationality will be introduced together with the main 
objectives. The input needed from the patients will be communicated and an oral informed 
consent will be requested. In case of a positive input the following questions will be asked: 
 
- How much pain do you experience at the moment in the knee where the procedure was 
performed in a scale of zero to ten where zero is ‘no pain’ and ten is ‘unbearable pain’? 
- Is the pain in the knee tolerable or not? 
- How much effect do you still perceive at the moment expressed in percent between 0 and 
100%? 
- How long do you think the treatment worked or is there still effect? 
- Do you experience at the moment functional improvement in comparison with before the 
treatment? 
- Which pain medication are you using at the moment? 
- Did you experience any adverse events? 
 
The conversation will be executed in the Dutch language. 
 
 
 
 

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3. STUDY SETTING AND POPULATION  
3.1 Study setting 
The enrollment period will be between 1 September 2017 and 30 June 2020. The patients 
recruited were treated in an outpatient setting in the multidisciplinary chronic pain center in 
Lanaken, Campus St. Barbara, ZOL. Patients with chronic knee pain who qualify for an 
conventional radiofrequency treatment of the genicular nerves were recruited. Prior a 
diagnostic block was performed and in case of positive results patients were treated with 
conventional radiofrequency ablation. Follow up in the pain clinic consisted of a minimum of 
one consultation after treatment at six weeks post procedure. Further follow up was planned 
according to the needs of the patient at the pain clinic, orthopedist or general practitioner. 
3.2 Population 
3.2.1 Inclusion criteria 
1. All patients with chronic knee pain who qualify for a conventional RF treatment of the 
genicular nerves  
 
3.2.2 Exclusion Criteria 
Patients will be excluded from participating in the study if the meet any of the following 
exclusion criteria: 
1. Refusal to participate  
2. A negative diagnostic block with lidocaine 2% 1 ml of the three genicular nerves 
defined as less than 50% pain reduction  
3. Chronic widespread pain 
 
4. STUDY OBJECTIVES 
4.1 The primary objective of this study is to evaluate the treatment success of the 
conventional radiofrequency treatment of the genicular nerves in patients on patients 
diagnosed with chronic knee pain due to osteoarthritis of the knee or PPSP at six weeks post 
treatment. Treatment success is defined as a global perceived effect of at least 50% at 
measurement time point compared to baseline.  
4.2 The secondary objectives are: 
• 
Evaluation of treatment effect at a third time point at the end of the inclusion period 
• 
Subgroup analysis of treatment success based on indication to treatment 
• 
Evaluation of subjective functional improvement 
• 
Evaluation of change in analgesics 
• 
Estimation of the duration of effect of the treatment 
• 
Adverse event 
 
 
 

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5. STUDY ENDPOINTS 
5.1 Primary endpoint:  
Proportion of patient with treatment success at week 6 defined as a global perceived effect of 
≥ 50% compared to baseline. 
 
5.2 Secondary endpoints: 
- 
Proportion of patients with treatment success at third time point defined as a global 
perceived effect of ≥ 50% compared to baseline. 
- 
NRS reduction at week 6 and at the third time point. 
- 
Subjective physical functioning at week 6 and at the third time point. 
- 
Duration effect of the treatment defined as the period with a GPE of ≥ 50%. 
- 
Change in use of strong opioids at week 6 and at the third time point. 
- 
Safety: number/type of adverse events. 
 
    6. TIME SCHEDULE 
Outcome / Time point 
Baseline 
Consultation 
prior to 
inclusion 
Diagnostic 
RF 
treatment 
RF 
treatment 
Consultation 
6 weeks 
post 
treatment 
Telephonic 
contact 
Age 
X 
 
 
 
 
Sex  
X 
 
 
 
 
Duration of symptoms 
X 
 
 
 
 
Previous knee surgery 
X 
 
 
 
 
Referring physician 
X 
 
 
 
 
Indication for treatment 
X 
 
 
 
 
NRS  
X 
 
 
X 
X 
Strong opioid use 
X 
 
 
X 
X 
Chronic widespread pain 
X 
 
 
 
 
NRS reduction ≥  50% 
 
X 
 
X 
X 
Treating physician 
 
 
X 
 
 
Subjective 
physical functioning score  
 
 
 
 
X 
GPE ≥  50% 
 
 
 
X 
X 
Adverse events 
 
 
 
X 
X 
Informed consent 
 
 
 
 
X 
 
    7.  STATISTICAL CONSIDERATIONS 
Data will be presented as mean values and standard deviations or as median values and 
interquartile range (IQR) depending on the distribution of the data. The average post-
treatment pain score will be estimated using linear mixed effects regression analysis using 
time since treatment as independent variable. We will use this multilevel approach as (most) 
patients contribute more than one post-treatment pain score to the dataset. This way, we will 
be able to estimate the 3 and 6 months effect of RF treatment. The statistical analysis will be 
performed using SPSS. 

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    8.  INFORMED CONSENT 
Patients in accordance with eligibility criteria will be contacted by mail to obtain written 
informed consent and afterwards by phone by the investigator. At the beginning of the 
contact oral informed consent will also be obtained. 
    9.  REFERENCES 
1. Grotle M, Hagen KB, Natvig B, et al. Prevalence and burden of osteoarthritis: results from 
a population survey in Norway. J Rheumatol. 2008; 35(4): 677–84. 
2. Murphy L, Schwartz TA, Helmick CG, et al. Lifetime risk of symptomatic knee osteo-
arthritis. Arthritis Rheum. 2008; 59: 1207–13. 
3.Lui SS, Buvanendran A, Rathmell JP, et al. A cross sectional survey on prevalence and 
risk factors for persistent post-surgical pain 1 year after total hip and knee replacement. 
Regional Anesthesia and Pain Medicine. 2012; 37(4): 415-22. 
4.Wylde V, HewlettS, LearmonthID, et al. Persistent pain after joint replacement: prevalence, 
sensory qualities, and post-operative determinants. PAIN. 2011; 152(3): 566-72. 
5.Scranton PE. Management of knee pain and stiffness after total knee arthroplasty. The 
Journal of Arthroplasty. 2001; 16(4): 428-35. 
6. Bistolfi A, Bettoni E, Aprato A, et al. The presence and influence of mild depressive 
symptoms on post-operative pain perception following primary total knee arthroplasty. Knee 
Surg Sports Traumatol Arthrosc 2015; 25: 2792-2800. 
7. Scott CE, Howie CR, MacDonald D, et al. Predicting dissatisfaction following total knee 
replacement: a prospective study of 1217 patients. J Bone Joint Surg Br. 2010; 92:1253-
1258. 
8. Park CN, White PB, Meftah M, et al. Diagnostic Algorithm for Residual Pain After Total 
Knee Arthroplasty. Orthopedics. 2016; 39: e246-252. 
9. Bistolfi A1, Zorzolo I, Rold I, et al. Radiofrequencies for painful total knee Arthroplasty: 
rationale and applications: A review. Physical Medicine and Rehabilitation Research. 2017; 
2(6): 1-4. 
10. Choi WJ, Hwang SJ, Song JG, et al. Radiofrequency treatment relieves chronic knee 
osteoarthritis pain: a double-blind randomized controlled trial. PAIN. 2011; 152(3): 481-487. 
11. Bhatia A, Peng P, Cohen SP. Radiofrequency procedures to relieve chronic knee pain: 
an evidence- based narrative review. Regional Anesthesia and Pain Medicine. 2016;  41(4): 
501-10.  
12. Qudsi-Sinclair S, Borrás-Rubio E, Abellan-Guillén JF, et al. A comparison of genicular 
nerve treatment using either radiofrequency or analgesic block with corticosteroid for pain 
after total knee arthroplasty: a double blind, randomized clinical study. Pain Practice. 2017; 
17(5): 578-88. 
13. Gupta A, Huettner DP, Dukewich M. Comparative effectiveness review of cooled versus 
pulsed radiofrequency ablation for the treatment of knee osteoarthritis: a systematic review. 
Pain Physician. 2017; 20(3): 155-71. 

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APPENDIX 
Description of the procedures: 
Conventional radiofrequency treatment of the genicular nerves is performed in an outpatient 
setting. Patients are not required to stop anticoagulation prior to procedure. During the 
procedure the patient is monitored using pulse oximetry. No sedation is administered so the 
patient is able to communicate and report the stimulation adequate. The patient is placed in a 
supine position on a fluoroscopy table with the index knee flexed 10-15° by placing a cushion 
in the popliteal fossa. 
Description of the procedure of the diagnostic nerve block 
The eligible patients underwent diagnostic genicular nerve blocks with local anesthetic, which 
were performed under ultrasound guidance. The targets included the SL, SM and IM 
genicular nerves which pass periosteal areas connecting the shaft of the femur to bilateral 
epicondyles and the shaft of the tibia to the medial epicondyle. Lidocaine (1 mL of 2%) was 
injected at each target site. Responses were recorded as positive if the participant 
experienced a decrease in numeric pain scores of at least 50%. Patients with a positive 
response were included in the RF procedures. 
Description of the procedure of conventional radiofrequency ablation 
The procedure is performed under sterile conditions. A 100 mm long, 22 G straight RF 
cannula/introducer with a probe/electrode with a 5 mm active tip is used for the procedure. 
No corticosteroids are injected to decrease the risk of complications such as systemic effects 
and infection. The superomedial, the superolateral and the inferomedial genicular nerve are 
targeted using a high frequency linear ultrasound. The inferolateral genicular nerve is not 
targeted because of its proximity to the common peroneal nerve with its motor branches. 
Superomedial genicular nerve 
 
The transducer is placed in a coronal orientation on the medial side of the proximal knee. 
After identifying the femoral medial epicondyle, the transducer is displaced proximally to 
image the junction between the epiphysis and diaphysis of the femur and the vastus medialis 
superficial to it, just anterior to the adductor tubercle. The skin and soft tissue are 
anesthetized with 1 ml lidocaine2% at the estimated entry point. The superomedial genicular 
artery may or may not be seen between the deep fascia of the muscle and the femur at this 
level. If the superomedial genicular artery is visualised just above the bony cortex, the 
cannula tip is placed next to it using an cephalad to caudad ‘in plane’ approach. If the artery 
is not visualised, the cannula is advanced until contact is made with the bony cortex at the 
junction also using an cephalad to caudad ‘in plane’ approach. A RF electrode is introduced 
in the cannula. Sensory stimulation (50Hz) is applied and produced paresthesia at a 
threshold of less than 0,5 V. The absence of fasciculations below 1 V is observed after motor 
stimulation at 2 Hz, confirming sufficient distance to relevant motor branches. If no sensory 
stimulation threshold is obtained at this position, the transducer is rotated in a transverse 
view and the needle tip is redirect towards the middle of the femur until sensory threshold is 
reached. 
 
 

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Inferomedial genicular nerve  
The transducer is placed in a coronal orientation on the medial side of the distal knee to 
visualize the junction of the tibial medial epiphysis and diaphysis, the inferomedial genicular 
artery and the medial collateral ligament. The skin and soft tissue are anesthetized with 1 ml 
lidocaine 2% at the estimated entry point. The inferomedial genicular artery may or may not 
be seen beneath the medial collateral ligament at the midpoint between the tibial medial 
epicondyle and the tibial insertion of the medial collateral ligament. If the inferomedial 
genicular artery is visualized just above the bony cortex, the cannula tip is placed next to it 
using an caudad to cephalad ‘in plane’ approach. If the artery is not visualized, the cannula is 
advanced until contact is made with the bony cortex at the junction also using an caudad tot 
cephalad ‘in plane’ approach. A RF electrode is introduced in the cannula. Sensory 
stimulation (50 Hz) is applied and produced paresthesia at a threshold of less than 0,5 V. 
The absence of fasciculations below 1 V is observed after motor stimulation at 2 Hz, 
confirming sufficient distance to relevant motor branches. If no sensory stimulation threshold 
is obtained at this position, the transducer is rotated in a transverse view and the needle tip is 
redirect towards the middle of the tibia until sensory threshold is reached.  
Superolateral genicular nerve 
The transducer is placed in a coronal orientation on the lateral side of the proximal knee. 
After identifying the femoral lateral epicondyle, the transducer is displaced proximally to 
image the junction between the epiphysis and diaphysis of the femur and the vastus lateralis 
superficial to it. The skin and soft tissue are anesthetized with 1 ml lidocaine 2% at the 
estimated entry point. The superolateral genicular artery may or may not be seen between 
the deep fascia of the muscle and the femur at this level. If the superolateral genicular artery 
is visualized just above the bony cortex, the cannula tip is placed next to it using an ‘in plane’ 
approach. If the artery is not visualized, the cannula is advanced until contact is made with 
the bony cortex at the junction also using an ‘in plane’ approach. A RF electrode is 
introduced in the cannula. Sensory stimulation (50 Hz) is applied and produced paresthesia 
at a threshold of less than 0,5 V. The absence of fasciculations below 1 V is observed after 
motor stimulation at 2 Hz, confirming sufficient distance to relevant motor branches. If no 
sensory stimulation threshold is obtained at this position, the transducer is rotated in a 
transverse view and the needle tip is redirect towards the middle of the femur until sensory 
threshold is reached. 
If all three target nerves were identified 1 ml of lidocaine 2% is injected before the start of a 
RF treatment without a fluoroscopic control. A treatment of 70°C at the tip is applied during 
90 seconds at each nerve. After the procedure, the patient is transferred to the recovery. 
After 30 minutes without any events, the patient is discharged at home. Home medication is 
continued postoperative. Patient is informed about potential transient increase in pain due to 
neuritis and alarm symptoms (fever, swelling, bleeding and motor weakness).