Anatomical Variation of Infrapatellar Innervation Determines Clinical Risk of Infrapatellar Neuropathy.

BACKGROUND: Infrapatellar neuropathy arises from traumatic, iatrogenic, or compression injury to the infrapatellar branch (IB) of the saphenous nerve. The risk of infrapatellar neuropathy has been shown to depend on the IB's anatomical course. The infrapatellar branch of the saphenous nerve (ISBN) has been discovered to take varying courses, and the IB can emerge directly from the femoral nerve. The variety of the IBSN's courses and the prevalence of cases involving the infrapatellar branch of the femoral nerve (IBFN) call the uniform IB course described in textbooks into question. OBJECTIVES: In this study, we aim to identify sites of IB emergence and their anatomical relations and evaluate them for their risk of neuropathy. STUDY DESIGN: The study is an anatomical prospective pilot study. SETTING: The setting is a single-center cadaveric study performed at the anatomical institute of the Medical University of Vienna. METHODS: Twenty-two anatomical specimens were evaluated for the relationship of their IBs to anatomical risk sites. The subsartorial course, distal sartorial penetration, and the crossing of the medial femoral epicondyle were assessed. The measurements and relations of the IB were determined with callipers and assessed by computational modelling. RESULTS: Nine IBs originated from the saphenous nerve, 11 originated from the femoral nerve, and 2 originated from both. The subsartorial course was most frequent in IBs of saphenous origin. Penetrating and profound distal sartorial relations correlated moderately with emergence type and were highest in the saphenous group. The crossing of the medial femoral epicondyle was the most common relation of IBs that emerged femorally. LIMITATIONS: The study's limitations were the low number of cadavers to examine and the confining of the exploration of knee extension to anatomical specimens that restricted an inferential analysis. CONCLUSION: Infrapatellar innervation can emerge from the saphenous nerve, the femoral nerve, or a combination of both, and the origin of the innervation determines the clinical risk for infrapatellar neuropathy. While innervation from the IBSN may lead to compression at the subsartorial course, distal sartorial penetration, and the crossing of the medial femoral epicondyle, innervation from the IBFN carries reduced anatomical risk for infrapatellar neuropathy.

Infrapatellar Branch of the Saphenous Nerve: Therapeutic Approaches to Chronic Knee Pain.

PURPOSE OF REVIEW: The infrapatellar branch of the saphenous nerve (IPS) is an under-investigated nerve that can be a source of chronic knee pain. This literature review aims to deliver an up-to-date review of chronic pain transmitted via the IPS along with therapeutic approaches available for pain refractory to conservative measures. RECENT FINDINGS: Knee pain transmitted via the IPS can arise from several etiologies. Damage to the IPS is often iatrogenic and develops following total knee arthroplasty, anterior cruciate ligament reconstruction, and other knee surgical procedures. Other causes of IPS-derived pain include entrapment of the nerve, neuromas, Schwannomas, and pain from knee osteoarthritis transmitted through the IPS.This article investigated therapeutic approaches to pain derived from the IPS. Common approaches included radiofrequency ablation, neuroma excisions, Schwannoma excision, nerve blocks, surgical exploration, surgical release of an entrapped nerve, cryoablation, and peripheral nerve stimulation. Pain scores, duration of pain relief, adverse events, and secondary outcomes were all included in this review. A subset of the patient population experiences chronic pain deriving from the IPS that is refractory to conservative treatment measures. This review aims to evaluate the etiologies and therapeutic approaches for chronic pain arising from the IPS refractory to conservative treatments.

Adductor canal block techniques do not lead to involvement of sciatic nerve branches: a radiological cadaveric study.

INTRODUCTION: Low and high volume mid-thigh (ie, distal femoral triangle) and distal adductor canal block approaches are frequently applied for knee surgical procedures. Although these techniques aim to contain the injectate within the adductor canal, spillage into the popliteal fossa has been reported. While in theory this could improve analgesia, it might also result in motor blockade due to coverage of motor branches of the sciatic nerve. This radiological cadaveric study, therefore, investigated the incidence of coverage of sciatic nerve divisions after various adductor canal block techniques. METHODS: Eighteen fresh, unfrozen and unembalmed human cadavers were randomized to receive ultrasound-guided distal femoral triangle or distal adductor canal injections, with 2 mL or 30 mL injectate volume, on both sides (36 blocks in total). The injectate was a 1:10 dilution of contrast medium in local anesthetic. Injectate spread was assessed using whole-body CT with reconstructions in axial, sagittal and coronal planes. RESULTS: No coverage of the sciatic nerve or its main divisions was found. The contrast mixture spread to the popliteal fossa in three of 36 nerve blocks. Contrast reached the saphenous nerve after all injections, whereas the femoral nerve was always spared. CONCLUSIONS: Adductor canal block techniques are unlikely, even when using larger volumes, to block the sciatic nerve, or its main branches. Furthermore, injectate reached the popliteal fossa in a small minority of cases, yet if a clinical analgesic effect is achieved by this mechanism is still unknown.

Bipolar radiofrequency ablation of genicular nerves in chronic knee pain: A novel technique for more complete sensory denervation.

BACKGROUND: Monopolar radiofrequency ablation (MRFA) of the genicular nerves has been considered the main interventional treatment for chronic knee pain. However, the variable locations of these nerves could suggest that traditional MRFA of genicular nerves may be insufficient to cover the area needed to provide complete sensory denervation. For these reasons, some alternatives have been proposed to achieve an increase in the lesion area that offers better outcomes such a bipolar radiofrequency ablation (BRFA). OBJECTIVE: To describe the efficacy and safety of the bipolar radiofrequency ablation (BRFA) of the genicular nerves in the patients with chronic knee pain. METHODS: A retrospective study was conducted in the Pain Medicine Department. Institutional review board approval from the Hospital Ethical Committee and informed consent were obtained. We reviewed our database for BRFA of genicular nerves from January 2018 to December 2021 for patients with chronic knee pain. The cannulas were placed using ultrasound guidance (10 cm, 22-gauge and 10 mm active curved tip), and each pair of cannulas were subjected to BRFA for 90 seconds at 80∘C. Data analysis was conducted using T-test for paired variables (Visual analogue scale and EuroQol, an instrument intended to complement other forms of quality-of-life measures). RESULTS: Twenty-five patients met inclusion criteria after excluding 7 based on the study design. The mean improvement of our patients according to the VAS was -3.98 (95%CI: -4.37 to -3.59) p< 0.0001 and EuroQol +0.416 (95%CI: 0.364 to 0.468) p< 0.0001. The mean duration of improvement was 8 (6-11) months after BRFA. There were no reported serious adverse events related to the procedure, only local pain for 24 to 48 hours in 3 patients. CONCLUSIONS: We can conclude that BRFA reduces procedural pain and increases the treatment area, providing more complete sensory denervation and improved clinical outcomes.

Temperature-Mediated Neural Interventions in Knee Osteoarthritis: a Review of Cryoneurolysis and Cooled Radiofrequency Ablation with Ultrasound Guidance.

PURPOSE OF REVIEW: Knee osteoarthritis is a debilitating chronic disease affecting nearly half of the world's population at some point in their lives. Treatment of pain and loss of function associated with this disease has been limited. In this review, we seek to explore how neural interventions with ultrasound guidance may be an emerging option for non-pharmacologic pain relief in patients with knee osteoarthritis. RECENT FINDINGS: Cryoneurolysis techniques have been demonstrated to provide pain relief out to 150 days post-treatment in knee osteoarthritis in select individuals. There have also been studies of cryoneurolysis pre-operatively to total knee replacement providing reduced pain, reduced opioid use post-operatively, and shorter hospital length of stay. Cooled radiofrequency ablation (CRFA) has been demonstrated to significantly reduce pain, improve functionality, and reduce pharmacologic needs in knee osteoarthritis out to 2 years. Both interventions appear to have increased accuracy with ultrasound, and CRFA appears to be associated with improved patient outcomes. The research demonstrates the efficacy of both cryoneurolysis and cooled radiofrequency ablation in the treatment of knee osteoarthritis. Ultrasound guidance in neurolysis provides an additional tool with real-time, high-accuracy nerve localization. These therapies should be considered for certain patients to assist in pain management in the non-operative and post-operative phase of knee osteoarthritis management. Further research is needed to further define the long-term effects and the long-term utility of the techniques in knee pain.

Diagnosis and Treatment of Post-Radiofrequency Synovial Knee Fistula: Case Report.

Recently, denervation therapies have drawn attention as a promising treatment, and cooled radiofrequency has been proposed as the best option to capture most of the genicular nerves. We present a rare case of synovial knee fistula after radiofrequency and its management. To the best of our knowledge, this is the first case reported in the literature. The treatment included immobilization and chemoprophylaxis. One week later, the fistula was closed, and 14 months later, the procedure was repeated without complications. Genicular radiofrequency ablation is an emerging technique, and providers should be aware of the reported complications to counsel patients and manage potential risks appropriately.

An alternative treatment option in older adults with knee osteoarthritis : Genicular nerve pulsed radiofrequency.

Osteoarthritis (OA), including knee OA (KOA), is an important cause of morbidity and disability in older adults. Pain management plays a major role in the treatment of KOA for pain relief and knee function improvement. Ultrasound-guided genicular nerve pulsed radiofrequency therapy is an effective, safe, nonradiative, and easily applicable treatment modality in older adults with KOA. It has a positive effect on geriatric syndromes, especially polypharmacy.

Fluoroscopic Confirmation of Needle Location in Ultrasound-guided Genicular Nerve Radiofrequency Thermocoagulation.

BACKGROUND: Radiofrequency thermocoagulation of genicular nerves is an effective treatment for chronic pain due to knee osteoarthritis. The procedure can be performed under fluoroscopic or ultrasonographic guidance. OBJECTIVES: The aim of this study was to fluoroscopically check the final location  of the needle in ultrasound-guided genicular nerve radiofrequency thermocoagulation and evaluate the treatment's success in patients with knee pain. STUDY DESIGN: A 2-center, prospective study. SETTING: A private clinic and a tertiary care health center. METHODS: Thirty-two patients who had unilateral knee pain, and grade 3-4 knee osteoarthritis according to the Kellgren-Lawrence classification were included. Following diagnostic genicular nerve blocks in patients whose knee pain was relieved by >= 50%, radiofrequency thermocoagulation was applied to these nerves. The final position of the needle was checked via fluoroscopy in anteroposterior and lateral planes. RESULTS: The needle was located in the one-third anterior portion of the bone shaft in 69 of 96 patients (71.9%), between one-third and two-thirds in 21 (21.9%), and in the one-third posterior portion in 6 (6.3%). The mean Numeric Rating Scale score for pain was 7.69 ± 0.99 before treatment, 4.03 ± 1.26 at one week, 2.53 ± 1.24 at one month, and 2.19 ± 1.71 at 3 months, indicating a statistically significant decrease (P < 0.001). LIMITATIONS: The lack of a study group in which genicular nerve radiofrequency thermocoagulation was performed under fluoroscopy guidance could be cited among the limitations of this clinical study. CONCLUSIONS: The final position of the needle tip in radiofrequency thermocoagulation of genicular nerves can exist at the one-third anterior of the bone shaft, without a need for further advancing the needle to the posterior portion. Although performed more distally compared to fluoroscopy guidance, ultrasound-guided genicular nerve radiofrequency thermocoagulation still provides effective analgesia.

Genicular nerve radiofrequency ablation for the treatment of chronic knee joint pain: a real-world cohort study with evaluation of prognostic factors.

BACKGROUND: Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment for chronic knee pain. However, there has been minimal investigation of real-world, long-term outcomes and factors that predict treatment success after GNRFA. OBJECTIVES: To evaluate the effectiveness of GNRFA for chronic knee pain in a real-world population and identify predictive factors. METHODS: Consecutive patients who underwent GNRFA at a tertiary academic center were identified. Demographic, clinical, and procedural characteristics were collected from the medical record. Outcome data were numeric rating scale (NRS) pain reduction and Patient Global Impression of Change (PGIC). Data were collected by standardized telephone survey. Predictors of success were evaluated with logistic and Poisson regression analyses. RESULTS: Of the 226 total patients identified, 134 (65.6 ± 12.7; 59.7% female) were successfully contacted and analyzed, with a mean follow-up time of 23.3 ± 11.0 months. Of those, 47.8% (n = 64; 95% CI: 39.5%-56.2%) and 61.2% (n = 82; 95% CI: 52.7%-69.0%) reported ≥50% NRS score reduction and ≥2-point NRS score reduction, respectively, and 59.0% (n = 79; 95% CI: 50.5%-66.9%) reported "much improved" on the PGIC questionnaire. Factors associated with a greater likelihood of treatment success (P < .05) were higher Kellgren-Lawrence osteoarthritis grade (2-4 vs 0-1); no baseline opioid, antidepressant, or anxiolytic medication use; and >3 nerves targeted. CONCLUSION: In this real-world cohort, approximately half of the participants experienced clinically meaningful improvements in knee pain after GNRFA at an average follow-up time of nearly 2 years. Factors associated with higher likelihood of treatment success were more advanced osteoarthritis (Kellgren-Lawrence Grade 2-4); no opioid, antidepressant, or anxiolytic medication use; and >3 nerves targeted.

Ultrasound-guided genicular nerve radiofrequency treatment: prospective randomized comparative trial of a 3-nerve protocol versus a 5-nerve protocol.

OBJECTIVES: Genicular nerve radiofrequency procedures increasingly are being performed to treat chronic pain due to knee osteoarthritis. Targeting additional sensory nerves and improving target identification by using ultrasound guidance could improve treatment success. The aim of this study was to compare the effectiveness of targeting only the traditional genicular nerves versus targeting the traditional genicular nerves plus 2 additional sensory nerves in ultrasound-guided genicular nerve radiofrequency procedures in patients with chronic knee osteoarthritis. METHODS: A total of 80 patients were randomized into 2 groups. Patients in the 3-nerve-targeted group received a genicular radiofrequency procedure in which the traditional genicular nerves were targeted: the superior lateral, superior medial, and inferior medial nerves. The 5-nerve-targeted group received a genicular radiofrequency procedure in which the recurrent fibular and infrapatellar branches of the saphenous nerve were targeted in addition to the traditional genicular nerves. The numeric rating scale, Short Form-36, Western Ontario and McMaster Universities Arthritis Index, Quantitative Analgesic Questionnaire, and patient satisfaction were evaluated before treatment, at week 1 after treatment, and at months 1, 3, and 6 after treatment. RESULTS: Both techniques provided significant pain reduction and functional improvement up to 6 months after the procedure (P < .05). The 5-nerve-targeted group showed significant improvement with regard to the numeric rating scale, Western Ontario and McMaster Universities Arthritis Index total, and Short Form-36 score compared with the 3-nerve-targeted group at each follow-up point. No differences in the Quantitative Analgesic Questionnaire or patient satisfaction scores were observed between the groups. CONCLUSIONS: The ultrasound-guided 5-nerve-targeted technique is a safe method and a more effective therapeutic procedure than the traditional 3-nerve-targeted technique for chronic knee osteoarthritis. TRIAL REGISTRATION: www.ClinicalTrials.gov ID: NCT05073887.

Chemical neurolysis of the genicular nerves for chronic refractory knee pain: an observational cohort study.

OBJECTIVE: Evaluate outcomes of genicular nerve chemical neurolysis (GChN) in a real-world population with chronic knee pain. DESIGN: Restrospective, observational cohort study. SETTING: Tertiary academic medical center. SUBJECTS: Consecutive patients who had undergone GChN ≥3 months prior. METHODS: Standardized surveys were collected by telephone and included the numerical rating scale, opioid analgesic use, and Patient Global Impression of Change. Age, sex, body mass index, duration of pain, history of arthroplasty, lack of effect from previous radiofrequency ablation, percentage relief from a prognostic block, and volume of phenol used at each injection site were extracted from charts. Descriptive statistics were calculated, and logistic regression analyses were performed to identify factors influencing treatment outcome. RESULTS: At the time of follow-up after GChN (mean ± SD: 9.9 ± 6.1 months), 43.5% (95% CI = 33.5-54.1) of participants reported ≥50% sustained pain reduction. On the Patient Global Impression of Change assessment, 45.9% (95% CI = 35.5-56.7) of participants reported themselves to be "very much improved" or "much improved." Of 40 participants taking opioids at baseline, 11 (27.5%; 95% CI = 14.6-43.9) ceased use. Of participants with a native knee treated, 46.3% reported ≥50% pain reduction, whereas of participants with an arthroplasty in the treated knee, 33.3% reported this threshold of pain reduction (P = .326). Logistic regression analyses did not reveal associations between treatment success and any of the factors that we evaluated. CONCLUSIONS: GChN could provide a robust and durable treatment effect in a subset of individuals with chronic knee pain with complicating factors traditionally associated with poor treatment outcomes, such as those with pain refractory to radiofrequency ablation or those who have undergone arthroplasty.

Radiofrequency Ablation of the Infrapatellar Branch of the Saphenous Nerve for the Treatment of Chronic Anterior Inferomedial Knee Pain.

INTRO: Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment for chronic knee pain related to osteoarthritis. It is often utilized when conservative management has failed and patients wish to avoid arthroplasty, are poor surgical candidates due to comorbid medical conditions, or in those suffering from persistent pain after arthroplasty. The classic targets for GNRFA include the superior lateral genicular nerve, superior medial genicular nerve, and inferior medial genicular nerve but multiple anatomic studies have demonstrated additional sensory innervation to the knee. OBJECTIVE: In this research article, we propose an image-guided technique that can safely target the infrapatellar branch of the saphenous nerve which also provides sensory innervation to the anterior capsule. PROPOSAL: The proposed technique includes variations for conventional bipolar radiofrequency ablation, cooled radiofrequency ablation, dual-tined bipolar radiofrequency ablation, and monopolar radiofrequency ablation using a long axis approach. The described technique is based on updated anatomic studies and takes into account safety concerns such as thermal risk to the skin and/or pes anserine tendons and breaching of the synovial cavity. CONCLUSION: Future clinical research should be performed to confirm the safety and effectiveness of this specific approach.

Painful total knee arthroplasty: Infrapatellar branch of the saphenous nerve selective denervation. A case series.

INTRODUCTION: Total knee arthroplasty (TKA) is a reliable and widespread solution for knee osteoarthritis treatment, but about 20% of the patients complains of persisting pain. Neuroma formation in the IPBSN (infrapatellar branch of the saphenous nerve) is an undervalued cause of persistent anterior pain after TKA. The aim of this study was to evaluate the effectiveness of the selective neuroma denervation on patients satisfaction and pain improvement. MATHERIAL AND METHODS: Between 2014 and 2020, we evaluated 13 patients suffering from persistent anterior knee pain and numbness after TKA who underwent a surgical neurectomy of the IPBSN. After clinical assessment and diagnosis confirmation, we carried out the surgery. Short Form 12 Health (SF12), Oxford Knee Score (OKS), and Numeric Rating Scale (NRS) have been collected before and after the procedure. After the surgical treatment, the symptom's resolution and patients' satisfaction were attested by the achievement of the Minimal ClinicallyImportantDifference(MCID) of the self-administered patient-reported outcome measures (PROMs). RESULTS: Our results showed a statistically significant improvement (p < 0.05) of patients pain perception (mean NRS improvement -4.2, SD 2.5) and overall satisfaction (with a mean increase in OKS of 14.5 points SD 9.4, and in SF12 of 6.5 points SD 4.0). CONCLUSIONS: Hence, our study suggests that selective neuroma denervation may be an effective solution to improve the quality of life of patients who develop this complication after TKA.

In vivo electrical conductivity measurement of muscle, cartilage, and peripheral nerve around knee joint using MR-electrical properties tomography.

This study aimed to investigate whether in vivo MR-electrical properties tomography (MR-EPT) is feasible in musculoskeletal tissues by evaluating the conductivity of muscle, cartilage, and peripheral nerve around the knee joint, and to explore whether these measurements change after exercise. This prospective study was approved by the institutional review board. On February 2020, ten healthy volunteers provided written informed consent and underwent MRI of the right knee using a three-dimensional balanced steady-state free precession (bSSFP) sequence. To test the effect of loading, the subjects performed 60 squatting exercises after baseline MRI, immediately followed by post-exercise MRI with the same sequences. After reconstruction of conductivity map based on the bSSFP sequence, conductivity of muscles, cartilages, and nerves were measured. Measurements between the baseline and post-exercise MRI were compared using the paired t-test. Test-retest reliability for baseline conductivity was evaluated using the intraclass correlation coefficient. The baseline and post-exercise conductivity values (mean ± standard deviation) [S/m] of muscles, cartilages, and nerves were 1.73 ± 0.40 and 1.82 ± 0.50 (p = 0.048), 2.29 ± 0.47 and 2.51 ± 0.37 (p = 0.006), and 2.35 ± 0.57 and 2.36 ± 0.57 (p = 0.927), respectively. Intraclass correlation coefficient for the baseline conductivity of muscles, cartilages, and nerves were 0.89, 0.67, and 0.89, respectively. In conclusion, in vivo conductivity measurement of musculoskeletal tissues is feasible using MR-EPT. Conductivity of muscles and cartilages significantly changed with an overall increase after exercise.

The combined treatment of entrapped Infrapatellar Branch of the Saphenous Nerve after ACL reconstruction: Ultrasound-guided perineural injection and acupotomy.

BACKGROUND: The anterior cruciate ligament (ACL) reconstruction (ACLR) under the arthroscopy is a widespread procedure for ACL rupture, which could stabilize knee and promote recovery. However, one of its complications is the injury of infrapatellar branch of saphenous nerve (IBSN). In traditional Chinese medicine, acupotomy functions via releasing and stripping adhesion tissues. Accordingly, acupotomy is suitable for the treatment of entrapped nerve injury and tissues adhesion. CASE DESCRIPTION: A 14-year-old man, who had ACLR before and returned to normal activity, presented with severe pain after a mild strain two weeks ago. The physical and imaging examinations revealed the compression injury of IBSN. METHODS: We provided the ultrasound-guided perineural injection of 0.4% lidocaine, while it only alleviates the symptoms temporally and partially. Acupotomy using a small needle knife (0.4*40 mm) was performed. RESULTS: The severe pain was immediately resolved. The visual analog pain scale (VAS) decreased from 10 to 1 and return to normal walking. The diameter of IBSN became smaller and the signal of peripheral soft tissue became hypoechoic in ultrasound. CONCLUSION: In this case, the combined treatments of ultrasound-guided perineural injection and acupotomy are thought to be innovative procedures for IBSN entrapment with relative long-lasting therapeutic effects.