Spasticity Treatment Beyond Botulinum Toxins

Botulinum toxin (BonT) is the mainstream treatment option for post-stroke spasticity. BoNT therapy may not be adequate in those with severe spasticity. There are a number of emerging treatment options for spasticity management. In this paper, we focus on innovative and revived treatment options that can be alternative or complementary to BoNT therapy, including phenol neurolysis, cryoneurolysis, and extracorporeal shock wave therapy.

Efficacy and Safety of Cryoablation Compared with Cooled Radiofrequency Ablation of Genicular Nerves in Advanced Osteoarthritis of the Knee: A Study Protocol of Single-Centric, Assessor-Blinded, Randomized, Parallel-Group, Non-inferiority Study

PURPOSE

In patients with symptomatic osteoarthritis knee (OAK), cryoneurolysis (CRYO) and cooled radiofrequency ablation (C-RFA) are reported to be effective and safe; however, they have not been compared directly. The objective of this study is to compare CRYO and C-RFA of the genicular nerve (GN) in terms of efficacy and safety profile in patients with Kellgren and Lawrence (KL) grade ≥ 3 OAK.

METHODS

This single-centric, assessor-blinded, randomized, parallel-group, non-inferiority study will include 80 patients with KL grade ≥ 3 OAK. The patients with ≥ 50% pain relief on diagnostic block of three GNs will be randomized to one of the two groups, i.e., CRYO (n = 40) or C-RFA (n = 40). The three target GNs for the interventions will include: superior medial, superior lateral, and inferior medial. The primary outcome will be efficacy of CRYO or C-RFA at 2, 12, and 24 weeks post-procedure based on the 11-point Numerical Pain Rating Scale. The secondary outcomes will be functional improvement based on 12-item Oxford Knee Score and safety of both the procedures. The study is registered in the Clinical Trials Registry-India.

CONCLUSION

CRYO and C-RFA provide pain relief and improve functional outcome by preventing transmission of pain signals, though by distinct mechanisms. While C-RFA is an established treatment modality, recent evidence supports CRYO in patients with OAK. This study intends to demonstrate non-inferiority of CRYO against C-RFA, thereby supporting the use of CRYO as an additional treatment modality in patients with KL grade ≥ 3 OAK.

Safety and Efficacy of Percutaneous Morton Neuroma Cryoneurolysis Under Ultrasound Guidance

PURPOSE

To assess the technical success, safety and early efficacy of Morton neuroma (MN) cryoneurolysis.

MATERIALS AND METHODS

Retrospective review of 54 consecutive patients with MN treated with cryoneurolysis after failure of conservative treatment, from September 2022 to June 2023. Outcomes measurements included technical success (defined a successful ultrasound-guided placement of the cryoprobe), procedural safety according to Cirse classification and change in 6 months post-procedure by pain numeric rating scale (pNRS).

RESULTS

A total of 59 MN were treated during 55 procedures. Mean procedure duration was 47 min, all patients were discharged 2 h after the intervention. Technical success was 98.1%. No Cirse grade 3, 4 or 5 complication was reported. Three grade 2 complication occurred, including two chilblain-type lesions and one bone insufficiency fracture. At 6 months post-procedure, pNRS score was significantly decreased (2.7 ± 2.2 vs 7.1 ± 1.1) (p < 0.0001), with a mean score decrease of 4.1points. Thirty-two patients (60.4%) reported a complete pain relief, 15 (28.3%) a partial pain relief and 6 (11.3%) no pain relief, or increased pain.

CONCLUSION

Cryoneurolysis seems to be safe for the treatment of Morton neuroma. Six-month pain relief is promising and needs to be confirmed at long term.

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.

Applications of Cryoneurolysis in Chronic Pain Management: a Review of the Current Literature

PURPOSE OF REVIEW

The purpose of this review is to evaluate and summarize the literature investigating cryoneurolysis in the treatment of various chronic pain pathologies.

RECENT FINDINGS

There is an increasing amount of interest in the use of cryoneurolysis in chronic pain, and various studies have investigated its use in lumbar facet joint pain, SI joint pain, post-thoracotomy syndrome, temporomandibular joint pain, chronic knee pain, phantom limb pain, neuropathic pain, and abdominal pain. Numerous retrospective studies and a more limited number of prospective, sham-controlled prospective studies suggest the efficacy of cryoneurolysis in managing these chronic pain pathologies with a low complication rate. However, more blinded, controlled, prospective studies comparing cryoneurolysis to other techniques are needed to clarify its relative risks and advantages.

Efficacy of cryoneurolysis versus intra-articular steroid in sacroiliac joint pain: A retrospective, case-control study

Background and Aims

Intra-articular steroids provide significant pain relief in sacroiliac joint pain (SIJP), but their action is short-lived. Cryoneurolysis is reported to produce prolonged pain relief in various pain conditions. However, its efficacy has not been evaluated in patients with SIJP. Thus, we compared the efficacy of cryoneurolysis with steroid injections in adult patients with SIJP.

Methods

This retrospective healthcare records review-based study involved 83 patients with SIJP. Patients were divided into two groups: cases (sacroiliac joint [SIJ] cryoneurolysis, n = 39) and controls (SIJ steroid injection, n = 44). An 11-point numeric pain rating scale (NPRS) was used to assess the pain severity at baseline and immediately, 1, 3 and 6 months post-intervention. A reduction of ≥50% in NPRS score immediately following SIJ cryoneurolysis and steroid injection was considered a successful outcome. The difference between the treatment groups was assessed with a Chi-square test, and P < 0.05 was considered statistically significant.

Results

Both cases and controls showed significantly decreased NPRS scores from baseline to immediately, 1 month, 3 months and 6 months postintervention (P < 0.001). However, compared to controls, cases had significantly lower NPRS scores at all time points (all P < 0.001). Moreover, a significantly greater proportion of cases had ≥50% decrease in NPRS score from baseline, that is, 1 month (97.44% vs. 75%, P = 0.004), 3 months (100% vs. 47.73%, P < 0.001) and 6 months (69.23% vs. 27.27%, P < 0.001).

Conclusion

Although both cryoneurolysis and intra-articular steroid injections provide significant pain relief immediately, 1, 3 and 6 months postintervention, cryoneurolysis resulted in significantly greater pain relief.

A Case Report of Cryoneurolysis for Dorsal Foot Pain and Toe Clawing in a Patient With Multiple Sclerosis

Toe clawing in patients with upper motor neuron disorders is often attributed to the flexor digitorum longus (FDL) and is a common presentation among patients with multiple sclerosis (MS). This movement may be painful because of the altered pressure distribution and may increase the risk of falls, heighten energy expenditure during gait, and lower gait speed. Cryoneurolysis is a minimally invasive treatment that may be beneficial for pain and focal muscle hypertonicity. An ambulatory patient with MS was treated bilaterally with cryoneurolysis to the superficial fibular nerves for pain on the dorsum of the foot, and to the intramuscular tibial nerve motor branch to FDL for toe clawing. The patient felt that toe clawing was immediately reduced during gait and noted the ability to voluntarily spread their toes. The patient stated that the neuropathic pain on the dorsum of the foot was fully eliminated immediately post procedure. The patient reported improved confidence in their gait, maintained independence, and reduced toe clawing during a structured interview 12 weeks after treatment. The effects lasted for 5.5 months before symptoms returned. Retreatment at 6 months reproduced the benefits. The patient reported a positive experience with cryoneurolysis for toe clawing and dorsal foot pain.

Body Habitus Impact on Success of Cryoneurolysis for Postoperative Total Knee Arthroplasty Pain Control: A Retrospective Cohort Study

Background

Cryoneurolysis utilizes temperatures below -20°C for nonpermanent analgesia to control pain in total knee arthroplasty (TKA). There is concern that body habitus could limit pain control because of accuracy of cryoneurolysis to subcutaneous nerves. This study aimed to determine the relationship between body habitus and effectiveness of cryoneurolysis on postoperative pain control.

Methods

A retrospective chart review was performed on patients undergoing cryoneurolysis before primary TKA from 2017 to 2019. Included were 114 patients (58 control group and 56 treatment group). Cryoneurolysis patients were divided into 3 groups (small, medium, and large) based on the soft tissue to femoral diaphysis ratio of 7 cm proximal to superior pole of the patella. Postoperative outcome measures were morphine equivalents, numerical rating score for pain, range of motion, and Knee Injury and Osteoarthritis Outcome Score Joint Replacement.

Results

The small cryoneurolysis group showed decreased opioid consumption at the 2, 6, and 12 weeks compared with control group, with morphine equivalents significantly decreased at 2 weeks for small compared with medium groups (54.3 vs 142.9, P = .0097). Numerical rating score for pain decreased significantly between small and medium groups (3.4 vs 4.0, P = .012) and between medium and large groups (4.0 vs 2.4, P = .012). Range of motion increased at 12 weeks for small group compared with medium group (118 vs 112, P = .042). There were no differences in any outcome measure between small and large groups.

Conclusions

Body habitus does not appear to affect efficacy of cryoneurolysis in controlling postoperative pain following TKA. Cryoneurolysis remains a useful tool for multimodal pain management.

Review of genicular artery embolization, radiofrequency ablation, and cryoneurolysis in the management of osteoarthritis-related knee pain

Osteoarthritis (OA) of the knee represents one of the most common diseases in the world, affecting an estimated 14 million people in the United States alone. Exercise therapy and oral pain medication are first-line treatments but have limited efficacy. Next-line treatments such as intra-articular injections are limited in durability. Moreover, total knee replacements, although effective, require surgical intervention, which has considerable variability in patient satisfaction. Novel minimally invasive image-guided interventions are becoming more widespread for treating OA-related knee pain. Recent studies of these interventions have revealed promising results, minor complications, and reasonable patient satisfaction. In this study, published manuscripts were reviewed in the field of minimally invasive, image-guided interventions for OA-related knee pain, with a focus on genicular artery embolization, radiofrequency ablation, and cryoneurolysis. Recent studies have demonstrated a significant decrease in pain-related symptoms following these interventions. Reported complications were mild in the reviewed studies. Image-guided interventions for OA-related knee pain exist as valuable options for patients who fail other therapies, may not be good surgical candidates, or wish to avoid surgical intervention. Further studies with randomization and an increased length of follow-up are needed to better characterize outcomes following these minimally invasive therapies.

Cooled radiofrequency ablation versus cryoneurolysis of the genicular nerves for the symptomatic pain management in knee osteoarthritis: a study protocol of a prospective, randomized, single-blinded clinical trial

BACKGROUND

Cooled radiofrequency ablation (CRFA) and cryoneurolysis (CRYO) are two novel methods of genicular neurolysis to relief pain in symptomatic knee osteoarthritis (KOA). In this study, the two methods will be compared, giving us the opportunity to investigate their efficacy, safety and complications.

METHODS

In this prospective randomized trial 70 patients with KOA will be recruited using a diagnostic block of four genicular nerves. Two groups will be created through software randomization: a CRFA group (35 patients) and a CRYO group (35 patients). The target of the interventions will be four genicular nerves; the superior medial, superior lateral, inferior medial, as well as the medial (retinacular) genicular branch from vastus intermedius. The primary outcome of this clinical trial will be the efficacy of CRFA or CRYO at 2-, 4-, 12-and 24-weeks post-intervention using the Numerical Rating Pain Scale (NRPS). The secondary outcomes are the safety of the two techniques, as well as the clinical evaluation using the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS), and the 7-point scale of Patient Global Impression of Change (PGIC).

DISCUSSION

These two novel techniques can block pain transmission through genicular nerves in different ways. In contrast to cryoneurolysis, the CRFA method has been well documented in the past. This is the first clinical trial to compare CRFA vs CRYO and draw conclusions about their safety and efficacy.

TRIAL REGISTRATION

ISRCTN87455770 [ https://doi.org/10.1186/ISRCTN87455770 ]. Registered 29/3/2022, first patient recruited 31/8/2022.

Relative Effects of Various Factors on Ice Ball Formation and Ablation Zone Size During Ultrasound-Guided Percutaneous Cryoneurolysis: A Laboratory Investigation to Inform Clinical Practice and Future Research

INTRODUCTION

Ultrasound-guided percutaneous cryoneurolysis provides analgesia using cold temperatures to reversibly ablate peripheral nerves. Cryoneurolysis probes pass a gas through a small internal annulus, rapidly lowering the pressure and temperature, forming an ice ball to envelope the target nerve. Analgesia is compromised if a nerve is inadequately frozen, and laboratory studies suggest that pain may be paradoxically induced with a magnitude and duration in proportion with the incomplete ablation. We therefore investigated the relative effects of various factors that may contribute to the size of the ice ball and the effective cryoneurolysis zone.

METHODS

A cryoprobe was inserted into a piece of meat, a gas was passed through for 2 min, and the resulting ice ball width (cross-section) and length (axis parallel to the probe) were measured using ultrasound, with the temperature evaluated in nine concentric locations concurrently.

RESULTS

The factor with the greatest influence on ice ball size was probe gauge: in all probe types, a change from 18 to 14 increased ice ball width, length, and volume by up to 70%, 113%, and 512% respectively, with minimum internal temperature decreasing as much as from -5 to -32 °C. In contrast, alternating the type of meat (chicken, beef, pork) and the shape of the probe tip (straight, coudé) affected ice ball dimensions to a negligible degree. The ice ball dimensions and the zone of adequate temperature drop were not always correlated, and, even within a visualized ice ball, the temperature was often inadequate to induce Wallerian degeneration.

CONCLUSIONS

Percutaneous probe design can significantly influence the effective cryoneurolysis zone; visualizing a nerve fully encompassed in an ice ball does not guarantee adequate treatment to induce the desired Wallerian degeneration because ice forms at temperatures between 0 and -20 °C, whereas only temperatures below -20 °C induce Wallerian degeneration. The correlation between temperatures in isolated pieces of meat and perfused human tissue remains unknown, and further research to evaluate these findings in situ appears highly warranted.

Ultrasound-guided percutaneous cryoneurolysis for management of acute sternal fracture pain

Background

Establishing adequate analgesia for rib and sternal fractures remains a challenge due to the prolonged nature of the associated pain. Historically, cryoneurolysis has demonstrated beneficial in treating chronic pain, and the recent development of hand-held devices has allowed its functionality to expand into the management of acute pain.

Case

We present a polytrauma patient with sternal and multiple rib fractures that underwent ultrasound-guided intercostal cryoneurolysis at bedside, resulting in significant analgesia lasting several weeks and improving mobilization. This is the first report of the utilization of cryoneurolysis to treat acute sternal fracture pain.

Conclusion

The most common sternal fracture pattern is transverse which only requires treatment of four intercostal nerves, making cryoneurolysis feasible in trauma centers. This portable, minimally invasive, and low risk technique has the added benefits of reducing opioid requirements, decreasing length of hospital stay, and improving mobility in polytrauma patients.

Extending Perioperative Analgesia with Ultrasound-Guided, Percutaneous Cryoneurolysis, and Peripheral Nerve Stimulation (Neuromodulation)

The use of regional anesthesia is key to a successful approach to improving postoperative analgesia, which involves local anesthetic deposition either around peripheral nerves or within a fascial plane. Unfortunately, the realistic duration even with continuous peripheral nerve blocks usually does not match the duration of surgical pain, comprising a major limitation. Here, the use of 2 interventional modalities-ultrasound-guided percutaneous cryoneurolysis and peripheral nerve stimulation-is discussed, both of which may be used to treat acute and subacute pain and may therefore have a positive impact on the incidence and severity of chronic pain development.

A Randomized Controlled Pilot Study Using Ultrasound-Guided Percutaneous Cryoneurolysis of the Infrapatellar Branch of the Saphenous Nerve for Analgesia Following Total Knee Arthroplasty

INTRODUCTION

Total knee arthroplasty (TKA) is frequently associated with severe, prolonged postsurgical pain, and therefore local anesthetic-based peripheral nerve blocks are commonly used for postoperative analgesia. Cryoneurolysis involves the use of freezing temperatures to provide a reversible sensory (and motor) block with a duration measured in weeks and months, more commensurate with the typical period of post-TKA pain. We therefore conducted a randomized controlled pilot study to evaluate the use of this modality for the treatment of pain following TKA to (1) determine the feasibility of and optimize the study protocol for a subsequent definitive clinical trial; and (2) estimate analgesia and opioid reduction within the first 3 postoperative weeks.

METHODS

A convenience sample of 16 patients undergoing primary TKA with a single-injection and/or continuous adductor canal nerve block were randomized to receive either active cryoneurolysis or a sham procedure targeting the infrapatellar branch of the saphenous nerve, in a participant-masked fashion. This was a pilot study with a relatively small number of participants, and therefore resulting data were not analyzed statistically.

RESULTS

Compared with participants receiving sham, the active treatment group reported slightly lower average and worst pain scores as well as opioid consumption and sleep disturbances due to pain at a majority of postoperative time points between postoperative days (POD) 4-21.

CONCLUSIONS

Preoperative ultrasound-guided cryoneurolysis of the infrapatellar branch of the saphenous nerve is feasible and may provide analgesic benefits for multiple weeks following TKA. A definitive randomized controlled trial appears warranted.

Reduction in opioid use with perioperative non-pharmacologic analgesia in total knee arthroplasty and ACL reconstruction: a systematic review

Introduction: The world’s opioid epidemic has gotten increasingly severe over the last several decades and projects to continue worsening. Orthopedic surgery is the largest contributor to this epidemic, accounting for 8.8% of postoperative opioid dependence cases. Total knee arthroplasty (TKA) and anterior cruciate ligament (ACL) reconstruction are commonly performed orthopedic operations heavily reliant on opioids as the primary analgesic in the peri- and immediate postoperative period. These downfalls highlight the pressing need for an alternate, non-pharmacologic analgesic to reduce postoperative opioid use in orthopedic patients. The presented systematic review aimed to analyze and compare the most promising non-pharmacologic analgesic interventions in the available literature to guide future research in such a novel field. Methods: A systematic search of PubMed, MEDLINE, Embase, Cochrane, and Web of Science was performed for studies published before July 2020 based on the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines, and the obtained manuscripts were evaluated for inclusion or exclusion against strict, pre-determined criteria. Risk-of-bias and GRADE (grades of recommendation, assessment, development, and evaluation) assessments were then performed on all included studies. Results: Six studies were deemed fit for inclusion, investigating three non-pharmacologic analgesics: percutaneous peripheral nerve stimulation, cryoneurolysis, and auricular acupressure. All three successfully reduced postoperative opioid use while simultaneously maintaining the safety and efficacy of the procedure. Discussion: The results indicate that all three presented non-pharmacologic analgesic interventions are viable and warrant future research. That said, because of its slight advantages in postoperative pain control and operational outcomes, cryoneurolysis seems to be the most promising. Further research and eventual clinical implementation of these analgesics is not only warranted but should be a priority because of their vast potential to reduce orthopedics surgeries’ contribution to the opioid epidemic.

Feasibility and efficacy of cryoneurolysis analgesia in robotic-assisted thoracoscopic surgery (CARTS): a pilot study

Opioid therapy has been the mainstay therapy of post-operative pain management in thoracic surgery patients. With the high incidence of chronic pain in thoracic surgery patients and adverse effects of opioids, we examined the safety and efficacy of cryoneurolysis as an adjunct for narcotic-free pain management in robotic-assisted thoracoscopic lobectomies. Ten consecutive patients undergoing robotic-assisted (DaVinci) pulmonary resection and cryoneurolysis were compared to ten patients managed without intraoperative cryoneurolysis. All patients received multimodal pain regimen including paravertebral blocks as per our institutional enhanced recovery pathway. Patients with chronic pain and chronic opioid use were excluded. We compared inpatient and outpatient opioid consumption measured in morphine equivalents (mme), incidence of opioid-free outpatient recovery, and adverse events. The two groups did not differ significantly in terms of baseline demographics. Both inpatient (88.13 vs 26.92 mme) and outpatient (118.5 vs 34.5 mme) use of narcotics were significantly lower in the cryoneurolysis group (p < 0.05) with seven of ten patients receiving cryoneurolysis able to recover without the use of opioids in the outpatient setting, compared to two in the control group. One patient reported post-operative neuralgia in each cryoneurolysis and control group. There were no readmissions in either group and mean length of stay was identical at 1.7 days in control group and 1.1 days in experimental group (p = 0.33). The use of intraoperative intercostal cryoneurolysis may safely reduce the utilization of outpatient opioids in patients undergoing robotic-assisted thoracoscopic surgery. A randomized controlled trial is warranted to validate these findings in a larger cohort of patients.

Cryoneurolysis' outcome on pain experience (COPE) in patients with low-back pain: study protocol for a single-blinded randomized controlled trial

Background

Low-back pain, including facet joint pain, accounts for up to 20 % of all sick leaves in DenmarkA proposed treatment option is cryoneurolysis. This study aims to investigate the effect of cryoneurolysis in lumbar facet joint pain syndrome.

Methods

A single-center randomized controlled trial (RCT) is performed including 120 participants with chronic facet joint pain syndrome, referred to the Department of Neurosurgery, Aarhus University Hospital. Eligible patients receive a diagnostic anesthetic block, where a reduction of pain intensity ≥ 50 % on a numerical rating scale (NRS) is required to be enrolled. Participants are randomized into three groups to undergo either one treatment of cryoneurolysis, radiofrequency ablation or placebo. Fluoroscopy and sensory stimulation is used to identify the intended target nerve prior to administrating the above-mentioned treatments. All groups receive physiotherapy for 6 weeks, starting 4 weeks after treatment. The primary outcome is the patients’ impression of change in pain after intervention (Patient Global Impression of Change (PGIC)) at 4 weeks follow-up, prior to physiotherapy. Secondary outcomes are a reduction in low-back pain intensity (numeric rating scale) and quality of life (EQ-5D, SF-36) and level of function (Oswestry Disability Index), psychological perception of pain (Pain Catastrophizing Scale) and depression status (Major Depression Inventory).

Data will be assessed at baseline (T0), randomization (T1), day one (T2), 4 weeks (T3), 3 (T4), 6 (T5) and 12 months (T6).

Discussion

This study will provide information on the effectiveness of cryoneurolysis vs. the effectiveness of radiofrequency ablation or placebo for patients with facet joint pain, and help to establish whether cryoneurolysis should be implemented in clinical practice for this patient population.

Trial registration

The trial is approved by the ethical committee of Central Jutland Denmark with registration number 1-10-72-27-19 and the Danish Data Protection Agency with registration number 666,852. The study is registered at Clinicaltrial.gov with the ID number NCT04786145.

Cryoneurolysis for the management of chronic pain in patients with knee osteoarthritis; a double-blinded randomized controlled sham trial

Objective

Pain is the principal symptom in knee osteoarthritis (OA). Current non-operative treatment options have only moderate effects and often patients experience persistent pain or side-effects. Novel advances in the field of cryoneurolysis applies low temperatures to disrupt nerve signaling at the painful area, providing pain relief. The primary aim of this randomized controlled trial (RCT) is to investigate if cryoneurolysis is superior to sham at decreasing pain intensity 2 weeks after the intervention in patients with knee OA. Secondary aims are to explore effects on pain, quality of life and functional performance over 24 months.

Methods

This two-arm, parallel-group RCT, approved by the Regional Ethics Committee, will randomly allocate patients (n = 94) to a cryoneurolysis intervention group + standardized education and exercise (CRYO) or a sham group + standardized education and exercise (SHAM) (1:1 ratio). Both groups will be assessed at baseline, 2 weeks post intervention, post education and exercise and at 6, 12 and 24 months after cryoneurolysis. The primary outcome is the NRS knee pain intensity score assessed 2 weeks post the intervention. Secondary outcome measures include functional performance (chair-stand test, 40 m walk, stair test and maximum voluntary contraction of the knee), patient reported outcomes (quality of life (EQ5D), Knee and osteoarthritis outcome scores (KOOS), among others), use of analgesics, and adverse events over 24 months.

Impact statement

Cryoneurolysis could potentially provide an effective, safe and non-pharmacological therapeutic option to treat pain in OA patients. The potential benefits include increased functional capacity and quality of life as a result of significant pain relief and improved benefits of physical exercise.

Trial registration

Clinicaltrials.gov, NCT03774121, registered 3 March 2018, http://www.clinicaltrials.gov

Interventional Cryoneurolysis: An Illustrative Approach

The application of advanced imaging guidance and the interventional radiology skill set has expanded the breadth of nerve and nerve plexus targets in the body for potential cryoneurolysis. Advancement of the basic science supporting cryoneurolysis has further solidified proceduralists' confidence and ability to select and manage patients clinically. As these procedures continue to evolve, a structured approach to the wide variety of indications is necessary.

Ultrasound-guided percutaneous intercostal cryoanalgesia for multiple weeks of analgesia following mastectomy: a case series

Background

Acute post-mastectomy pain is frequently challenging to adequately treat with local anesthetic-based regional anesthesia techniques due to its relatively long duration measured in multiple weeks.

Case

We report three cases in which preoperative ultrasound-guided percutaneous intercostal nerve cryoneurolysis was performed to treat pain following mastectomy. Across all postoperative days and all three patients, the mean pain score on the numeric rating scale was 0 for each day. Similarly, no patient required any supplemental opioid analgesics during the entire postoperative period; and, no patient reported insomnia or awakenings due to pain at any time point. This was a significant improvement over historic cohorts.

Conclusions

Ultrasound-guided percutaneous cryoanalgesia is a potential novel analgesic modality for acute pain management which has a duration that better-matches mastectomy than other currently-described techniques. Appropriately powered randomized, controlled clinical trials are required to demonstrate and quantify both potential benefits and risks.

Novel Methodologies in Regional Anesthesia for Knee Arthroplasty

Maximizing analgesia is critical following joint arthroplasty because postoperative pain is a major barrier to adequate physical therapy. Continuous peripheral nerve blocks have been the mainstay for acute pain management in this population; however, this and similar techniques are limited by their duration of action. Cryoneurolysis and peripheral nerve stimulation are two methodologies used for decades to treat chronic pain. With the advent of portable ultrasound devices and percutaneous administration equipment, both procedures may now be suitable for treatment of acute pain. This article reviews these two modalities and their application to joint arthroplasty.

Cryoneurolysis to treat the pain and symptoms of knee osteoarthritis: a multicenter, randomized, double-blind, sham-controlled trial

OBJECTIVE

Evaluate the efficacy and safety/tolerability of cryoneurolysis for reduction of pain and symptoms associated with knee osteoarthritis (OA).

DESIGN

Randomized, double-blind, sham-controlled, multicenter trial with a 6-month follow-up in patients with mild-to-moderate knee OA. Patients were randomized 2:1 to cryoneurolysis targeting the infrapatellar branch of the saphenous nerve (IPBSN) or sham treatment. The primary endpoint was the change from baseline to Day 30 in the Western Ontario and McMaster Osteoarthritis Index (WOMAC) pain score adjusted by the baseline score and site. Secondary endpoints, including visual analogue scale (VAS) pain score and total WOMAC score, were tested in a pre-defined order.

RESULTS

The intent-to-treat (ITT) population consisted of 180 patients (n = 121 active treatment, n = 59 sham treatment). Compared to the sham group, patients who received active treatment had a statistically significant greater change from baseline in the WOMAC pain subscale score at Day 30 (P = 0.0004), Day 60 (P = 0.0176), and Day 90 (P = 0.0061). Patients deemed WOMAC pain responders at Day 120 continued to experience a statistically significant treatment effect at Day 150. Most expected side effects were mild in severity and resolved within 30 days. The incidence of device- or procedure-related adverse events was similar in the two treatment groups with no occurrence of serious or unanticipated adverse device effects (ADE).

CONCLUSIONS

Cryoneurolysis of the IPBSN resulted in statistically significant decreased knee pain and improved symptoms compared to sham treatment for up to 150 days, and appeared safe and well tolerated.

An in vitro analysis of the size and shape of cryolesions for facet joint denervation

OBJECTIVES

Lumbar facet joint syndrome (LFJS) is the cause of lower back pain in 15-54% of the patients. Clinical studies of cryotherapy for LFJS have reported promising outcomes. However, few studies have focused on the technical aspects of cryoneurolysis for LFJS. The aim of the study was to determine the size and shape of cryolesions in vitro and to determine how they are affected by the duration of freezing, size of the cryoprobe and distance and angulation to an osseous boundary layer.

MATERIALS AND METHODS

Two different cryolesion generators were used. Cryolesions were generated in tempered physiologic NaCl solution in the vicinity of an osseous surface. The size of the cryoprobes, duration of freezing, distance to the bone surface and angulation of the probe were studied. Cryolesions were recorded with a video camera during their emergence. Images at distinct time points were analysed using digital image processing software.

RESULTS

The probe size, the system in use and the duration of the freezing cycle were the main determinants for the size of the cryolesion. The vicinity of the osseous boundary resulted in a modest increase in the size of the cryolesion. Angulation of the cryoprobe towards the osseous boundary is of minor importance for the size of the contact area to the nerve.

CONCLUSION

For cryoneurolysis of LFJS, duration of freezing, temperature and probe size are the main determinants of lesion size and thus the probability of success of the procedure. A tangential approach of the probe is not essential.

Percutaneous freezing of sensory nerves prior to total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is a common procedure resulting in significant post-operative pain. Percutaneous cryoneurolysis targeting the infrapatellar branch of the saphenous nerve and anterior femoral cutaneous nerve could relieve post-operative knee pain by temporarily blocking sensory nerve conduction.

METHODS

A retrospective chart review of 100 patients who underwent TKA was conducted to assess the value of adding perioperative cryoneurolysis to a multimodal pain management program. The treatment group consisted of the first 50 patients consecutively treated after the practice introduced perioperative (five days prior to surgery) cryoneurolysis as part of its standard pain management protocol. The control group consisted of the 50 patients treated before cryoneurolysis was introduced. Outcomes included hospital length of stay (LOS), post-operative opioid requirements, and patient-reported outcomes of pain and function.

RESULTS

A significantly lower proportion of patients in the treatment group had a LOS of ≥2days compared with the control group (6% vs. 67%, p<0.0001) and required 45% less opioids during the first 12weeks after surgery. The treatment group reported a statistically significant reduction in symptoms at the six- and 12-week follow-up compared with the control group and within-group significant reductions in pain intensity and pain interference at two- and six-week follow-up, respectively.

CONCLUSIONS

Perioperative cryoneurolysis in combination with multimodal pain management may significantly improve outcomes in patients undergoing TKA. Promising results from this preliminary retrospective study warrant further investigation of this novel treatment in prospective, randomized trials.

LEVEL OF EVIDENCE

III.

Development and validation of a new method for locating patella sensory nerves for the treatment of inferior and superior knee pain

Background

Radiofrequency ablation and percutaneous cryoneurolysis to relieve knee pain requires treating large areas to ensure coverage due to high variability in the sensory innervation of the knee and limitations of current methods for defining treatment targets. This study sought to define and validate a new treatment approach targeting the major sensory nerves of the superior patella and expand upon previous work to define a more efficient treatment approach targeting the sensory nerves of the inferior patella.

Methods

Transcutaneous electrical nerve stimulation and ultrasound were used to evaluate the location and relationship of the cutaneous nerves to the superior and inferior aspects of the knee in 25 healthy volunteers. Using information derived from these evaluations, investigators defined new linear target treatment areas, or treatment lines, using anatomical landmarks, which were validated against locations of sensory nerves through cadaveric dissection of 15 fresh specimens.

Results

The proposed treatment lines captured the vast majority of nerve branching variations during cadaveric validation.

Conclusion

This study defined treatment lines, identifiable using only anatomical landmarks, which effectively target the nerves responsible for superior and inferior knee pain and reduce the total treatment area and procedure time when administering treatments such as radiofrequency ablation and cryoneurolysis.