In vivo study on the short-term effect of radiofrequency energy on chondromalacic patellar cartilage and its correlation with calcified cartilage pathology in an equine model

Radiofrequency-Based Chondroplasty Creates a Precise Area of Targeted Chondrocyte Death With Minimal Necrosis Outside the Target Zone: A Systematic Review

Purpose

To systematically examine the effects of radiofrequency (RF) ablation or coblation (controlled ablation) on chondrocyte viability following knee chondroplasty in preclinical literature to determine the effectiveness and safety of RF-based techniques.

Methods

A literature search was performed in September 2022 using PubMed and Scopus using the following search terms combined with Boolean operators: "chondroplasty," "radiofrequency," "thermal," "knee," "chondral defect," "articular cartilage," and "cartilage." The inclusion criteria consisted of preclinical studies examining the effect of RF ablation or coblation on chondrocytes during knee chondroplasty. Exclusion criteria consisted of studies reporting chondroplasty in joints other than the knee, clinical studies, in vitro studies using animal models, case reports, non-full-text articles, letters to editors, surveys, review articles, and abstracts. The following data were extracted from the included articles: author, year of publication, chondral defect location within the knee and chondral characteristics, RF probe characteristics, cartilage macroscopic description, microscopic chondrocyte description, and extracellular matrix characteristics.

Results

A total of 17 articles, consisting of 811 cartilage specimens, were identified. The mean specimen age was 63.4 ± 6.0 (range, 37-89) years. Five studies used monopolar RF devices, 7 studies used bipolar RF devices, whereas 4 studies used both monopolar and bipolar RF devices. Time until cell death during ablation at any power was reported in 5 studies (n = 351 specimens), with a mean time to cell death of 54.4 seconds (mean range, 23.1-64) for bipolar RF and 56.3 seconds (mean range, 12.5-64) for monopolar RF devices. Chondrocyte cell death increased with increased wattage, while treatment time was positively correlated with deeper cell death.

Conclusions

In this systematic review, histologic analysis demonstrated that RF-based chondroplasty creates a precise area of targeted chondrocyte death, with minimal evidence of necrosis outside the target zone. Caution must be exercised when performing RF-based chondroplasty due to the risk of cell death with increased application time and wattage.

Clinical Relevance

Although RF ablation has demonstrated favorable results in preliminary trials, including smoother cartilage and less damage to the surrounding healthy tissue, the risks versus benefits of the procedure are largely unknown. Caution must be exercised when performing RF-based chondroplasty in the clinical setting due to the risk of cell death with increased application time and wattage.

The Arthroscopic Application of Radiofrequency in Treatment of Articular Cartilage Lesions

Articular cartilage lesion is a common disease to be treated by arthroscopic surgery. It will eventually progress to osteoarthritis without proper management, which can affect patients’ work and daily life seriously. Although mechanical debridement and laser have been used clinically for its treatment, due to their respective drawbacks, radiofrequency has drawn increasing attention from clinicians as a new technique with more advantages. However, the safety and efficacy of radiofrequency have also been questioned. In this article, the scope of application of radiofrequency was reviewed following an introduction of its development history and mechanism, and the methods to ensure the safety and effectiveness of radiofrequency through power and temperature control were summarized.

Use of a Novel Variable Power Radiofrequency Ablation System Specific for Knee Chondroplasty: Surgical Experience and Two-Year Patient Results

Introduction Although stabilisation of knee cartilage lesions (chondroplasty) may be performed with an arthroscopic shaver, more recently, radiofrequency (RF) ablation has gained in popularity. However, their remain some concerns about the avoidance of thermal injury, chondrolysis, and osteonecrosis with the use of RF devices. Methods We reviewed the outcomes of 85 knee chondroplasties performed with a new RF ablation wand designed for knee chondroplasty. Lesion details and Chondropaenia Severity Score (CSS) were recorded for each patient. We evaluated the occurrence of adverse outcomes, post-operative complications, and the need for further surgery. Post-operative outcomes scores (Oxford Knee Score [OKS], Knee injury and Osteoarthritis Outcome Score [KOOS], and International Knee Documentation Committee [IKDC] subjective knee outcome) were recorded at a minimum of one-year follow-up. Results At the final mean follow-up of 27.5 months (range: 12-46.6 months), 12 (14%) knees had undergone or were listed for further surgery. Four patients had corticosteroid injections for ongoing pain at a median 7.5 months (range: 5-20 months) post-operatively. There were no observed re-operations considered to be caused by complications related to thermal injury. Of the six patients listed for or undergoing knee arthroplasty, five (83%) had grade 4 lesions found at the arthroscopic chondroplasty. A negative correlation was noted between CCS, and post-operative IKDC subjective score (R=-0.35), KOOS Sports (R=-0.39), and KOOS QoL (R=-0.36). Conclusions We found that RF chondroplasty appeared safe, and there were no concerns with regard to thermal injury. Functional outcome appeared to be related to the quality of chondral and meniscal tissue throughout all knee compartments, with better results for isolated grade 2 and 3 cartilage lesions.

Adjunct use of radiofrequency coblation for osteochondritis dissecans in children: A case report

RATIONALE

Osteochondritis dissecans (OCD) lesions involve disruption of the osteochondral unit along articular surfaces, with significant potential for joint deterioration if not managed appropriately.

PATIENT CONCERNS

A 15-year-old male presented with persistent and insidious right knee pain, which had worsened following a collision with another player during a basketball game, resulting in episodes of locking.

DIAGNOSES

Magnetic resonance imaging revealed a lateral trochlear OCD extending into the anterior lateral femoral condyle.

INTERVENTIONS

Chondral fraying was observed along the margins of the OCD. Retrograde drilling ensued with use of a 0.045-inch Kirschner wire throughout the lesion to a depth that would allow for penetration of healthy underlying subchondral bone to create an influx of healing factors. Three resorbable pegs were arthroscopically placed through an accessory portal overlying the lesion to stabilize the fracture and compress the gapped cartilage mantle to reduce flow of synovial fluid behind the lesion. Bipolar radiofrequency coblation was used to stabilize the chondral fraying and seal the gap along the periphery of the lesion.

OUTCOMES

The patient was put on a nonweight bearing protocol for 6 weeks, after which crutches and brace were discontinued, but therapy persisted. Repeat imaging at 3 months demonstrated excellent interval healing. The patient was released to slowly engage impact activities. Although he returned at approximately 8 months postoperatively with a contralateral anterior cruciate ligament tear, he reported the operative knee with the OCD was doing extremely well.

LESSONS

Radiofrequency coblation appears to be a viable strategy as an adjunct to management for OCD in children.

Radiofrequency Chondroplasty May Not Have A Long-Lasting Effect in the Treatment of Concomitant Grade II Patellar Cartilage Defects in Humans

The effect of radiofrequency chondroplasty on cartilage tissue is not well studied. This prospective pilot study investigates the effect of radiofrequency chondroplasty on International Cartilage Repair Society (ICRS) grade II patellar cartilage defects using high-resolution magnetic resonance imaging (MRI) with T2 mapping. Six consecutive patients were treated for ICRS grade II patellar cartilage defects using radiofrequency chondroplasty. Before surgery and at defined follow-ups (2 weeks, 4 and 12 months) a high-resolution morphological 3 Tesla MRI with quantitative T2 mapping was performed. At baseline MRI, global T2 values of cartilage defects were increased (46.8 ms ± 9.7) compared to healthy cartilage (35.2 ms ± 4.5) in the same knee which served as reference. Two weeks after treatment, global T2 values (39.2 ms ± 7.7) of the defect areas decreased. However, global T2 values of the defect areas increased beyond the preoperative levels at 4 months (47.4 ms ± 3.1) and 12 months (51.5 ms ± 5.9), respectively. Zonal T2 mapping revealed that the predominant changes in T2 values occurred at the superficial cartilage layer. T2 mapping appears to be an ideal method to monitor cartilage degeneration after chondroplasty. Based on the small sample size of this pilot study, radiofrequency chondroplasty may cause cartilage damage and may not have a long-lasting effect in the treatment of grade II patellar cartilage defects. In five out of six patients, postoperative cartilage damage was observed on quantitative MRI. This study was therefore terminated before completion. We recommend only addressing the pathology which indicated arthroscopy and leaving concomitant cartilage lesions untreated.

The history of radiofrequency energy and Coblation in arthroscopy: a current concepts review of its application in chondroplasty of the knee

Radiofrequency energy has had widespread use for a variety of surgical procedures. Its application in orthopedic surgery initiated with shoulder instability. Over the last couple decades it has been applied as surgical tool for cartilage treatment as well. There have been significant gains in its technology and our understanding of its potential benefits. We address its history and advancements in becoming a surgical tool for cartilage lesions along with a review of recent long-term follow up studies.

What are the current indications for use of radiofrequency devices in hip arthroscopy? A systematic review

The role of radiofrequency energy (RFE) devices has been minimally studied in hip arthroscopy. The purpose of this study was to determine the role of RFE devices in hip arthroscopy through a systematic review of the literature. We searched the PubMed database using the following Medical Subject Heading terms: hip arthroscopy, hip radiofrequency, thermal capsulorrhaphy, thermal chondroplasty and radiofrequency debridement. Two authors independently reviewed the literature and included articles based on predetermined inclusion criteria. We excluded review, technique and experimental articles. After title and abstract review, we selected 293 articles for full-text review. Ten articles met the inclusion and exclusion criteria. For the included articles, a total of 305 hips underwent arthroscopy with concomitant RFE treatment at a mean age of 25.7 years. Eight articles presented patient-reported outcome (PRO) instruments, one study did not report an outcome instrument but utilized an evaluation of postoperative range of motion (ROM) and 1 year magnetic resonance image (MRI) and computed tomography (CT) imaging. The remaining article measured only the ROM pre- and postoperatively. Only one of the articles reviewed reported complications. Current evidence on the safety and indications for use of RFE devices in hip arthroscopy is insufficient. The literature shows mixed results regarding its use in hip arthroscopy. Although the use of thermal energy is not without risk, if used judiciously and appropriate precautions are taken to avoid damage to adjacent tissues, those devices can be useful for the treatment of certain intra-articular hip pathologies arthroscopically.

RFE based chondroplasty in wrist arthroscopy indicates high risk for chrondocytes especially for the bipolar application

Background

The application of radiofrequency energy (RFE) has become widespread for surgical performed chondroplasty especially due to the anticipated sealing effect, however the safety of this procedure in the wrist remains unclear. The purpose of this study was to investigate the subchondral temperature during radiofrequency energy (RFE) application simulating chondroplasty in an arthroscopic setting of the wrist.

Methods

A chondroplasty of the lunate fossa was performed during an arthroscopy setting on 14 cadaver arms using monopolar or biopolar RFE. The temperature was recorded simultaneously from 7 predefined anatomical landmarks.

Results

The mean temperature for both application modes did not exceed more than 30°C at all measured points, except for the lunate fossa. The highest subchondral measured peak temperature was 49.35°C (monopolar) and 69.21°C (bipolar) in the lunate fossa. In addition, the temperature decreased for both radiofrequency (RF) devices depending on the distance of the sensors to the RF-probe.

Conclusion

It remains to be questionable how safe RFE can be used for chondroplasty in wrist arthroscopy under continuous irrigation and constant movement to obtain the desired sealing effect. However, the bipolar device should be applied with more caution since peak temperature in the lunate fossa almost reached 70°C even under continuous irrigation.

A review of current concepts in radiofrequency chondroplasty

Radiofrequency (RF) chondroplasty is a promising treatment of chondral defects. The purpose of this study is to summarize current literature reporting the use of radiofrequency energy as an alternative treatment to mechanical shaving in chondroplasty. This review depicts the basic understanding of RF energy in ablating cartilage while exploring the basic science, laboratory evidence and clinical effectiveness of this form of chondroplasty. Laboratory studies have indicated that RF energy decreases inflammatory markers in the cartilage as well as providing optimal results with smoothing of chondral clefts. There have been concerns of chondrolysis due to heat damage of chondrocytes; however, this is unsubstantiated in clinical studies. These clinical trials have highlighted that RF energy is a safe and efficacious method of chondroplasty when compared to the mechanical shaving technique.

The acute effect of bipolar radiofrequency energy thermal chondroplasty on intrinsic biomechanical properties and thickness of chondromalacic human articular cartilage

Radio frequency energy (RFE) thermal chondroplasty has been a widely-utilized method of cartilage debridement in the past. Little is known regarding its effect on tissue mechanics. This study investigated the acute biomechanical effects of bipolar RFE treatment on human chondromalacic cartilage. Articular cartilage specimens were extracted (n = 50) from femoral condyle samples of patients undergoing total knee arthroplasty. Chondromalacia was graded with the Outerbridge classification system. Tissue thicknesses were measured using a needle punch test. Specimens underwent pretreatment load-relaxation testing using a spherical indenter. Bipolar RFE treatment was applied for 45 s and the indentation protocol was repeated. Structural properties were derived from the force-time data. Mechanical properties were derived using a fibril-reinforced biphasic cartilage model. Statistics were performed using repeated measures ANOVA. Cartilage thickness decreased after RFE treatment from a mean of 2.61 mm to 2.20 mm in Grade II, II-III, and III specimens (P < 0.001 each). Peak force increased after RFE treatment from a mean of 3.91 N to 4.91 N in Grade II and III specimens (P = 0.002 and P = 0.003, respectively). Equilibrium force increased after RFE treatment from a mean of 0.236 N to 0.457 N (P < 0.001 each grade). Time constant decreased after RFE treatment from a mean of 0.392 to 0.234 (P < 0.001 for each grade). Matrix modulus increased in all specimens following RFE treatment from a mean 259.12 kPa to 523.36 kPa (P < 0.001 each grade). Collagen fibril modulus decreased in Grade II and II-III specimens from 60.50 MPa to 42.04 MPa (P < 0.001 and P = 0.005, respectively). Tissue permeability decreased in Grade II and III specimens from 2.04 ∗10(-15) m(4)/Ns to 0.91 ∗10(-15) m(4)/Ns (P < 0.001 and P = 0.009, respectively). RFE treatment decreased thickness, time constant, fibril modulus, permeability, but increased peak force, equilibrium force, and matrix modulus. While resistance to shear and tension could be compromised due to removal of the superficial layer and decreased fibril modulus, RFE treatment increases matrix modulus and decreases tissue permeability which may restore the load- bearing capacity of the cartilage.

Targeted In Situ Biosynthetic Transcriptional Activation in Native Surface-Level Human Articular Chondrocytes during Lesion Stabilization

OBJECTIVE

Safe articular cartilage lesion stabilization is an important early surgical intervention advance toward mitigating articular cartilage disease burden. While short-term chondrocyte viability and chondrosupportive matrix modification have been demonstrated within tissue contiguous to targeted removal of damaged articular cartilage, longer term tissue responses require evaluation to further clarify treatment efficacy. The purpose of this study was to examine surface chondrocyte responses within contiguous tissue after lesion stabilization.

METHODS

Nonablation radiofrequency lesion stabilization of human cartilage explants obtained during knee replacement was performed for surface fibrillation. Time-dependent chondrocyte viability, nuclear morphology and cell distribution, and temporal response kinetics of matrix and chaperone gene transcription indicative of differentiated chondrocyte function were evaluated in samples at intervals to 96 hours after treatment.

RESULTS

Subadjacent surface articular cartilage chondrocytes demonstrated continued viability for 96 hours after treatment, a lack of increased nuclear fragmentation or condensation, persistent nucleic acid production during incubation reflecting cellular assembly behavior, and transcriptional up-regulation of matrix and chaperone genes indicative of retained biosynthetic differentiated cell function.

CONCLUSIONS

The results of this study provide further evidence of treatment efficacy and suggest the possibility to manipulate or induce cellular function, thereby recruiting local chondrocytes to aid lesion recovery. Early surgical intervention may be viewed as a tissue rescue, allowing articular cartilage to continue displaying biological responses appropriate to its function rather than converting to a tissue ultimately governed by the degenerative material property responses of matrix failure. Early intervention may positively impact the late changes and reduce disease burden of damaged articular cartilage.

The use of radiofrequency energy for arthroscopic chondroplasty in the knee

We present a review of the current literature surrounding the use of radiofrequency energy for arthroscopic chondroplasty in the knee. This review article summarizes basic science, clinical efficacy, and recent advances in the understanding of radiofrequency energy use for the treatment of chondral lesions. Laboratory evidence of increased mechanical stability and decreased release of inflammatory mediators associated with the use of radiofrequency energy chondroplasty is described with clinical evidence of decreased pain and increased functional scores when compared with mechanical chondroplasty. We re-examine concerns about the immediate side effects of radiofrequency energy use, including damage to local structures, in light of new potentially contradictory results, as well as the progression of techniques and probe design. However, although reported complications are few, because the quality of clinical evidence about safety and efficacy remains low, we suggest cautious and judicious use of this technology until future research has clearly defined the long-term clinical outcomes and risks.

Native Chondrocyte Viability during Cartilage Lesion Progression: Normal to Surface Fibrillation

OBJECTIVE

Early surgical intervention for articular cartilage disease is desirable before full-thickness lesions develop. As early intervention treatments are designed, native chondrocyte viability at the treatment site before intervention becomes an important parameter to consider. The purpose of this study is to evaluate native chondrocyte viability in a series of specimens demonstrating the progression of articular cartilage lesions to determine if the chondrocyte viability profile changes during the evolution of articular cartilage disease to the level of surface fibrillation.

DESIGN

Osteochondral specimens demonstrating various degrees of articular cartilage damage were obtained from patients undergoing knee total joint replacement. Three groups were created within a patient harvest based on visual and tactile cues commonly encountered during surgical intervention: group 1, visually and tactilely intact surfaces; group 2, visually intact, tactilely soft surfaces; and group 3, surface fibrillation. Confocal laser microscopy was performed following live/dead cell viability staining.

RESULTS

Groups 1 to 3 demonstrated viable chondrocytes in all specimens, even within the fibrillated portions of articular cartilage, with little to no evidence of dead chondrocytes. Chondrocyte viability profile in articular cartilage does not appear to change as disease lesion progresses from normal to surface fibrillation.

CONCLUSIONS

Fibrillated partial-thickness articular cartilage lesions are a good therapeutic target for early intervention. These lesions retain a high profile of viable chondrocytes and are readily diagnosed by visual and tactile cues during surgery. Early intervention should be based on matrix failure rather than on more aggressive procedures that further corrupt the matrix and contribute to chondrocyte necrosis of contiguous untargeted cartilage.

Histopomorphic evaluation of radiofrequency mediated débridement chondroplasty

The use of radiofrequency devices has become widespread for surgical ablation procedures. When ablation devices have been deployed in treatment settings requiring tissue preservation like débridement chondroplasty, adoption has been limited due to the collateral damage caused by these devices in healthy tissue surrounding the treatment site. Ex vivo radiofrequency mediated débridement chondroplasty was performed on osteochondral specimens demonstrating surface fibrillation obtained from patients undergoing knee total joint replacement. Three radiofrequency systems designed to perform débridement chondroplasty were tested each demonstrating different energy delivery methods: monopolar ablation, bipolar ablation, and non-ablation energy. Treatment outcomes were compared with control specimens as to clinical endpoint and histopomorphic characteristics. Fibrillated cartilage was removed in all specimens; however, the residual tissue remaining at the treatment site displayed significantly different characteristics attributable to radiofrequency energy delivery method. Systems that delivered ablation-based energies caused tissue necrosis and collateral damage at the treatment site including corruption of cartilage Superficial and Transitional Zones; whereas, the non-ablation system created a smooth articular surface with Superficial Zone maintenance and without chondrocyte death or tissue necrosis. The mechanism of radiofrequency energy deposition upon tissues is particularly important in treatment settings requiring tissue preservation. Ablation-based device systems can cause a worsened state of articular cartilage from that of pre-treatment. Non-ablation energy can be successful in modifying/preconditioning tissue during débridement chondroplasty without causing collateral damage. Utilizing a non-ablation radiofrequency system provides the ability to perform successful débridement chondroplasty without causing additional articular cartilage tissue damage and may allow for other cartilage intervention success.

Impact of monopolar radiofrequency energy on subchondral bone viability

The purpose of this study was to analyze the impact of monopolar radiofrequency energy treatment on subchondral bone viability. The femoral grooves of six chinchilla bastard rabbits were exposed bilaterally to monopolar radiofrequency energy for 2, 4 and 8 s, creating a total of 36 defects. An intravital fluorescence bone-labeling technique characterized the process of subchondral bone mineralization within the 3 months following exposure to radiofrequency energy and was analyzed by widefield epifluorescence optical sectioning microscopy using an ApoTome. After 2 s of radiofrequency energy exposure, regular fluorescence staining of the subchondral bone was evident in all samples when compared to untreated areas. The depth of osteonecrosis after 4 and 8 s of radiofrequency energy treatment averaged 126 and 942 microm at 22 days (P < .05; P < .01). The 4 s treatment group showed no osteonecrosis after 44 days whereas the depth of osteonecrosis extended from 519 microm at 44 days (P < .01), to 281 microm at 66 days (P < .01) and to 133 microm at 88 days (P < .05) after 8 s of radiofrequency energy application. Though radiofrequency energy may induce transient osteonecrosis in the superficial zone of the subchondral bone, the results of this study suggest that post-arthroscopic osteonecrosis appears to be of only modest risk given the current clinical application in humans.

Comparison of mechanical debridement and radiofrequency energy for chondroplasty in an in vivo equine model of partial thickness cartilage injury

OBJECTIVE

The purpose of this study was to develop a long-term model of cartilage injury that could be used to compare the effects of radiofrequency energy (RFE) and mechanical debridement as a treatment.

METHODS

Partial thickness fibrillation of patellar cartilage was created in 16 mature ponies. Three months after the initial surgery all injured patellae were randomly selected to receive one of the four treatments (n = 8/treatment): (1) control, (2) mechanical debridement with a motorized shaver, (3) TAC-CII RFE probe, and (4) CoVac 50 RFE probe. The ponies were euthanized 22 months after treatment. Macroscopic appearance of the cartilage surface was scored, vital cell staining was used to determine chondrocyte viability and light microscopy was used to grade the morphometric changes within the cartilage. Mechanical properties (aggregate modulus, Poisson's ratio and permeability) also were determined and compared to normal uninjured cartilage.

RESULTS

There were no differences in the cartilage surface scores among the treatment groups and control samples (P > 0.05). The maximum depth of cell death and the percentage of dead area in control and mechanical debridement groups were significantly less than those in both RFE groups. There were no significant differences in maximum depth and the percentage of dead area between the two RFE treatment groups. Histologic scores demonstrated better cartilage morphology for the control and mechanical debridement groups than those of RFE groups. However, even with full thickness chondrocyte death, the matrix in the RFE treated sections was still retained and the mechanical properties of the treated cartilage did not differ from the mechanical debridement group.

CONCLUSION

RFE caused greater chondrocyte death and more severe morphological changes compared to untreated degenerative cartilage and mechanical debridement in this model.