Temperature requirements for altering the morphology of osteoarthritic and nonarthritic articular cartilage: in vitro thermal alteration of articular cartilage

Heat-Related Complications from Radiofrequency and Electrocautery Devices Used in Arthroscopic Surgery: A Systematic Review

Purpose

To investigate the occurrence of heat-related complications from radiofrequency and electrocautery devices in patients undergoing arthroscopic surgery.

Methods

A systematic review was performed using the PubMed/Medline, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Cochrane databases, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All studies reporting complications after arthroscopy using electrosurgery devices were included. Only English- and Dutch-language articles were included. Basic science/nonclinical studies/human cadaveric studies and animal studies were excluded. Article selection was performed by 2 separate reviewers. Interobserver agreement of the selection procedure was determined by Cohen’s kappa. All included articles were critically appraised using an adapted version of the ROBINS-I tool.

Results

Twenty-five studies were included in this systematic review. A total of 309 cases of heat-related complications were identified. Chondrolysis was present in 45 cases and dermal burns in 15 cases. Axillary nerve injuries were reported in 197 cases of arthroscopic adhesive capsulitis release. However, it was unclear whether these injuries were directly related to the overheating of the arthroscopic fluid. No one specific risk factor for thermal complications was identified, but related factors included the leakage of the arthroscopy fluid, use of a thermal device continuously for a long period of time, proximity of the thermal device to the tissue, intra-articular local anesthetic injection or the use of intra-articular pain pumps, and certain surgical procedures, such as thermal capsulorrhaphy, capsular release, and synovectomy.

Conclusions

The most common heat-related complications in arthroscopy are dermal burns and chondrolysis. Risk factors include leakage of arthroscopy fluid, use of a thermal device, intra-articular anesthetics/pain pumps, and performing specific surgical procedures.

Level of Evidence

Systematic review of level III-IV studies.

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.

Electrocautery in arthroscopic surgery: intra-articular fluid temperatures above 43 °C cause potential tissue damage

PURPOSE

The use of electrocautery during arthroscopy may heat intra-articular saline and subsequently damage intra- and extra-articular tissue. Newer electrocautery devices have the ability to measure the outflow fluid temperature and switch off before reaching a certain threshold; however, the scientific evidence establishing these temperature thresholds' potential for inadvertent damage is lacking. The aim of this study was to analyse current available literature on temperature thresholds for tissue damage after exposure to heated fluid and provide a recommendation for the maximum temperature of intra-articular fluid to prevent tissue damage.

METHODS

In February 2018, a systematic literature review was performed using the MEDLINE/PubMed and Embase databases. Inclusion was limited to studies investigating temperature thresholds for thermal damage to at least one of the tissues of interest: skin, bone, cartilage, soft tissues, and nerves. Studies not reporting specific temperature thresholds for thermal damage were excluded.

RESULTS

Twenty articles were selected for the final evaluation and data extraction. Varying temperature thresholds, based on the lowest reported temperature causing tissue damage, were found for the different tissues of interest: 44 °C for dermal tissues, between 47 and 50 °C for bony tissues, 50 °C for cartilage, between 43 and 55 °C for soft tissues, and 43 °C for nerves.

CONCLUSION

Based on the current literature, a temperature threshold for intra-articular fluid of 43 °C during an arthroscopic procedure is recommended to prevent tissue damage. Higher temperatures may cause damage to surrounding intra- and extra-articular tissues. The threshold for irreversible damage is likely to be higher. In clinical practise, one should be aware of possible heating of intra-articular fluid when using electrocautery and related risk of tissue damage.

LEVEL OF EVIDENCE

III.

Quantitative Analysis of Surface Contouring with Pulsed Bipolar Radiofrequency on Thin Chondromalacic Cartilage

The purpose of this study was to evaluate the quality of surface contouring of chondromalacic cartilage by bipolar radio frequency energy using different treatment patterns in an animal model, as well as examining the impact of the treatment onto chondrocyte viability by two different methods. Our experiments were conducted on 36 fresh osteochondral sections from the tibia plateau of slaughtered 6-month-old pigs, where the thickness of the cartilage is similar to that of human wrist cartilage. An area of 1 cm² was first treated with emery paper to simulate the chondromalacic cartilage. Then, the treatment with RFE followed in 6 different patterns. The osteochondral sections were assessed for cellular viability (live/dead assay, caspase (cell apoptosis marker) staining, and quantitative analysed images obtained by fluorescent microscopy). For a quantitative characterization of none or treated cartilage surfaces, various roughness parameters were measured using confocal laser scanning microscopy (Olympus LEXT OLS 4000 3D). To describe the roughness, the Root-Mean-Square parameter (Sq) was calculated. A smoothing effect of the cartilage surface was detectable upon each pattern of RFE treatment. The Sq for native cartilage was Sq = 3.8 ± 1.1 μm. The best smoothing pattern was seen for two RFE passes and a 2-second pulsed mode (B2p2) with an Sq = 27.3 ± 4.9 μm. However, with increased smoothing, an augmentation in chondrocyte death up to 95% was detected. Using bipolar RFE treatment in arthroscopy for small joints like the wrist or MCP joints should be used with caution. In the case of chondroplasty, there is a high chance to destroy the joint cartilage.

Comparison Between 2 Types of Radiofrequency Ablation Systems in Arthroscopic Rotator Cuff Repair: A Randomized Controlled Trial

Background:

Radiofrequency ablation is commonly used in arthroscopic rotator cuff repair (RCR). New technology devices incorporating a plasma bubble may generate lower intra-articular temperatures and be more efficient.

Purpose:

To compare a plasma ablation device with a standard ablation device in arthroscopic RCR to determine which system is superior in terms of intra-articular heat generation and diathermy efficiency.

Study Design:

Randomized controlled trial; Level of evidence, 1.

Methods:

This was a single-center randomized controlled trial. The inclusion criteria were adult patients undergoing primary RCR. Patients were randomized preoperatively to the standard ablation group (n = 20) or plasma ablation group (n = 20). A thermometer was inserted into the shoulder joint during surgery, and the temperature, surgery, and diathermy times of radiofrequency ablation were measured continually.

Results:

No significant differences were found between the standard ablation group and plasma ablation group for maximum temperature (38.20°C and 39.38°C, respectively; P = .433), mean temperature (31.66°C and 30.64°C, respectively; P = .757), minimum temperature (21.83°C and 23.45°C, respectively; P = .584), and baseline temperature (28.49°C and 29.94°C, respectively; P = .379). Similarly, no significant differences were found for surgery time (74 and 75 minutes, respectively; P = .866) and diathermy time (10 minutes for both; P = .678). Seven patients registered transient high temperatures greater than 45°C.

Conclusion:

There was no difference between plasma ablation and standard ablation in terms of intra-articular temperature in the joint and diathermy efficiency. Transient high intra-articular temperatures occurred in both groups.

Registration:

ACTRN1261300056970 (Australian New Zealand Clinical Trials Registry).

Debridement of Articular Cartilage: The Natural Course

Chondral defects of the knee are quite common, affecting an estimated 10% to 12% of the population. Symptomatic chondral defects are thought to be persistent and possibly progressive. Less is known about the natural history of asymptomatic chondral lesions. Traditional treatment of chondral lesions has involved arthroscopic debridement with a mechanical shaver. Radiofrequency chondroplasty has been explored as a possible alternative or adjuvant to mechanical chondroplasty. The role of chondroplasty in the setting of knee osteoarthritis is more controversial. Early studies demonstrated promising results of arthroscopic debridement in the context of knee arthritis. However, publications in the last 10 to 15 years have brought into question the role of arthroscopic debridement in the setting of knee osteoarthritis. The purpose of this chapter is to explore the role of arthroscopic debridement in the treatment of chondral defects.

In Vivo Arthroscopic Temperatures: A Comparison Between 2 Types of Radiofrequency Ablation Systems in Arthroscopic Anterior Cruciate Ligament Reconstruction-A Randomized Controlled Trial

PURPOSE

To compare a plasma ablation device with a standard ablation device in anterior cruciate ligament (ACL) reconstruction to determine which system is superior in terms of intra-articular heat generation and diathermy efficiency.

METHODS

This was a prospective, randomized controlled trial. The inclusion criteria were adult patients undergoing primary ACL reconstruction. Patients were randomized preoperatively to the standard ablation group or the plasma ablation group. A thermometer was inserted into the inferior suprapatellar pouch, and the temperature, time, and duration of radiofrequency ablation were measured continually.

RESULTS

No significant differences were found between the standard ablation system and the plasma ablation system for maximum temperature (29.77°C and 29.34°C, respectively; P = .95), mean temperature (26.16°C and 26.99°C, respectively; P = .44), minimum temperature (22.66°C and 23.94°C, respectively; P = .54), and baseline temperature (26.80°C and 27.93°C, respectively; P = .35). Similarly, no significant differences were found for operative time (82.90 minutes and 80.50 minutes, respectively; P = .72) and mean diathermy activation times (2.6 minutes for both systems; P = .90). The between-system coefficient of variation for the measured parameters ranged from 0.12% to 3.69%. No intra-articular readings above the temperature likely to damage chondrocytes were recorded. The mean irrigation fluid temperature had a significant correlation with the maximum temperature reached during the procedure (Spearman rank correlation, r = 0.87; P < .01).

CONCLUSIONS

No difference in temperature was observed between the standard ablation and plasma ablation probes during ACL reconstruction. Temperatures did not exceed critical temperatures associated with chondrocyte death.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Management of Patellofemoral Arthritis: From Cartilage Restoration to Arthroplasty

The management of patellofemoral cartilage lesions is controversial and should begin with a comprehensive nonsurgical treatment plan. Patients with patellofemoral cartilage lesions in whom nonsurgical treatment fails may be candidates for surgical treatment. Surgical treatment strategies for the management of patellofemoral cartilage lesions are guided by the size, quality, and location of the defect. Recent advancements in cartilage restoration and arthroplasty techniques as well as appropriate patient selection and meticulous surgical technique have resulted in promising outcomes in patients with patellofemoral cartilage lesions who undergo surgical treatment.

Thermal stress potentiates bupivacaine chondrotoxicity

PURPOSE

The primary objective of this study was to determine whether thermal stress potentiates the chondrotoxic effect of bupivacaine, resulting in decreased articular chondrocyte viability compared with exposure to bupivacaine alone.

METHODS

Bovine articular cartilage explants and cultured chondrocytes were treated with a range of thermal exposures (10 to 20 minutes at 37°C to 65°C) to create time/temperature viability curves and to determine threshold conditions for cell death. A second set of experiments was performed to determine whether subthreshold thermal stress potentiates bupivacaine toxicity. Explants were exposed to 37°C or 55°C for 10 or 20 minutes, and cultured chondrocytes were exposed to 37°C or 45°C for 10 or 20 minutes. Thirty minutes later, the explants and chondrocytes were treated with either 0.9% normal saline solution or 0.5% bupivacaine for 30 minutes. Chondrocyte viability was quantified 24 hours after treatment.

RESULTS

There was a temperature- and time-dependent decrease in chondrocyte viability above the thermo-toxicity threshold in both intact cartilage explants and cultured chondrocytes (55°C and 45°C, respectively; P < .05). Chondrocyte viability in cartilage explants was significantly lower after treatment with thermal stress for 10 or 20 minutes followed by bupivacaine for 30 minutes compared with treatment with bupivacaine at 37°C (bupivacaine and 55°C for 10 minutes, 0.09% ± 0%; bupivacaine and 55°C for 20 minutes, 0.08% ± 0%; bupivacaine and 37°C for 10 minutes, 37.4% ± 1.2% [P < .001]; and bupivacaine and 37°C for 20 minutes, 47.1% ± 0.8% [P < .001]). A similar trend was seen in cultured chondrocytes, although it was not statistically significant (P > .05).

CONCLUSIONS

Thermal stress potentiates the chondrotoxic effects of bupivacaine in intact cartilage, leading to decreased chondrocyte viability compared with exposure to bupivacaine alone.

CLINICAL RELEVANCE

Intra-articular injection of bupivacaine after arthroscopic procedures during which cartilage is exposed to elevated temperatures, such as with prolonged use of radiofrequency probes, may increase the risk of chondrocyte toxicity.

In vivo temperature measurement in the subacromial bursa during arthroscopic subacromial decompression

BACKGROUND

The purpose of the study was to evaluate whether use of a bi-polar radiofrequency (RF) ablation wand would cause excess heating, which may lead to collateral damage to the surrounding tissues during arthroscopic subacromial decompression. Cadaveric studies have shown that high temperatures can potentially be reached when using RF ablation wands in arthroscopic shoulder surgery. Only 1 other published study assesses these temperature rises in the clinical setting.

METHODS

Fifteen patients were recruited to participate in the study. A standard arthroscopic subacromial decompression was performed using continuous flow irrigation, with intermittent use of the RF ablation wand for soft tissue debridement. The temperature of the irrigation fluid within the subacromial bursa and the outflow fluid from the suction port of the wand were measured during the procedure using fiber-optic thermometers.

RESULTS

The mean peak temperature recorded in the subacromial bursa was 32.0°C (29.3-43.1°C), with a mean rise from baseline of 9.8°C. The mean peak temperature recorded from the outflow fluid from the wand was 71.6°C (65.6-77.6°C), with a mean rise from baseline of 49.4°C.

CONCLUSION

High temperatures were noted in the outflow fluid from the wand; however, this was not evident in the subacromial bursa itself. Use of room temperature inflow fluid, maintenance of flow through the bursa, and avoidance of prolonged uninterrupted use of the wand all appear to ensure that safe temperatures are maintained in the subacromial bursa not only in the laboratory but also in a clinical setting.

The effect of irrigation solution at different temperatures on articular cartilage metabolism

PURPOSE

The purpose of this study was to determine the effects of saline solution at different temperatures on the metabolism of chondrocytes.

METHODS

Porcine osteochondral explants were precultured under laboratory conditions. The cartilage explants were placed in saline solution. Twenty-four explants were randomly divided into 4 groups. Explants were immersed at 4°C group I, at room temperature (24°C) in group II, at normal knee temperature (32°C) in group III, and at near-core body temperature (37°C) in group IV. All specimens were immersed for 2 hours. Lactate and proteoglycan production and RNA yield analysis were performed to evaluate the changes in cartilage metabolism at different temperatures.

RESULTS

Explants immersed in cold (4°C) saline solution showed the significantly lowest RNA yields, lactate production, and proteoglycan content. Explants immersed in cold solutions (4°C and 24°C) showed significantly lower RNA yields, lower lactate production, and lower proteoglycan content than explants in warmer solution groups (32°C and 37°C).

CONCLUSION

The findings of this study suggest that short-term exposures to cold including room temperature may have markedly detrimental effects on chondrocyte function. Our findings also indicate that exposures to cold saline solution suppress chondrocyte metabolism and RNA synthesis.

CLINICAL RELEVANCE

Using warmer irrigation solution that is closer to body temperature is more physiologic and causes less ultrastructural damage than colder solution.

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.

Ablation of articular cartilage with an erbium:YAG laser: an ex vivo study using porcine models under real conditions-ablation measurement and histological examination

BACKGROUND AND OBJECTIVES

The use of an erbium:YAG laser in arthroscopic surgery has the advantage of a precise treatment of soft tissue. Due to the high absorption in water, the laser energy is perfectly matched to smoothing the hydrous, fibrillated articular cartilage surface. In minimal invasive surgery, the workspace is filled with aqueous liquids for enlargement. This appears contrary to the absorption characteristics of erbium:YAG laser radiation in water. The purpose of this study was to evaluate the ablated volume per pulse of cartilage lesions and the potential side effects including thermal damage and tissue necrosis.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-four osteochondral specimens of porcine knee joints were irradiated with an Er:YAG laser completely submerged in water, with distances to the cartilage surface of 1, 3 and 5 mm and pulse durations of 75 and 100 microseconds. To keep a constant peak power of approximately 6 kW, pulse energies of 450 and 580 mJ were used at a pulse repetition rate of 15 Hz. After a histological preparation, ablated volumes, depths, and widths of the cuts were investigated. Additionally, laser protocols were correlated with different markers of cartilage tissue damage and apoptosis.

RESULTS

Ablation could be observed for every measurement. The influence of the distance showed a statistical significance (P < 0.001) for the volume, depth, and width of the cuts. For the pulse duration, statistical significance (P < 0.001) was found only for the volume and the depth. We observed no loss of proteoglycan or collagen type II. The total cell number, cell morphology, and number of apoptotic cells in an area close to the cutting edge and in a corresponding unaffected area of the same specimens revealed no differences regardless of the applied protocol.

CONCLUSION

The use of an Er:YAG laser demonstrates the successful application in liquid environments for cartilage removal without any damage of the surrounding tissue.

Mechanical chondroplasty: early metabolic consequences in vitro

PURPOSE

The purpose of this study was to determine the depth of penetration from mechanical chondroplasty and metabolic consequences of this procedure on the remaining articular cartilage.

METHODS

Mechanical chondroplasty was performed in vitro on a portion of fresh grade I or II articular cartilage from 8 human knee arthroplasty specimens. Treated and control (untreated) explants (approximately 30 mg) were cut from the cartilage. The explants were divided into 2 groups, day 1 and day 4, placed separately in a 48-well plate containing media, and incubated at 37 degrees C for 24 hours. After the 24-hour incubation, the explants were weighed on day 1 and day 4, and explant media were removed and tested for total proteoglycan synthesis and aggrecan synthesis. At time 0, 2 sets (2.6 mm each) of treated and control cartilage slices were cut with a precision saw. One set was stained for confocal laser microscopy via a cytotoxicity stain to determine cell viability. The second set was stained with H&E to determine depth of penetration.

RESULTS

The mean depth of penetration was 252.8 +/- 78 microm. There was no significant difference (P > .25) between total proteoglycan synthesis for control versus treatment groups on day 1 or 4. Aggrecan synthesis was significantly reduced on day 1 when normalized for tissue weight (P = .019) and double-stranded deoxyribonucleic acid (P = .004). On day 4, no significant difference was detected. Confocal laser microscopy did not show cell death below the zone of treatment.

CONCLUSIONS

There was no significant metabolic consequence caused by chondroplasty to the remaining articular cartilage, and the zone of injury was limited to the treatment area.

CLINICAL RELEVANCE

Mechanical chondroplasty causes no significant metabolic consequences to articular cartilage under these conditions.

Effects of thermal energy on chondrocyte viability

OBJECTIVE

To determine the critical temperature that reduces chondrocyte viability and evaluate the ability of chondrocytes to recover after exposure to the critical temperature.

SAMPLE POPULATION

Cartilage explants obtained from the humeral heads of 30 sheep.

PROCEDURES

In a randomized block design, 318 full-thickness cartilage explants were collected from 30 humeral heads of sheep and cultured for up to 14 days. On the first day of culture (day 0), explants were subjected to temperatures of 37 degrees , 45 degrees , 50 degrees , 55 degrees , 60 degrees , or 65 degrees C for 5 minutes by heating culture tubes in a warming block. The ability for chondrocytes to recover after exposure to the critical temperature was determined by evaluating viability at days 0, 1, 3, 7, and 14 days after heating. Images were analyzed by use of confocal laser microscopy.

RESULTS

Analysis of images revealed a significant decrease in live cells and a significant increase in dead cells as temperature increased. Additionally, the deepest layer of cartilage had a significantly lower percentage of live cells, compared with values for the 3 most superficial layers. Chondrocytes did have some ability to recover temporarily after the initial thermal insult.

CONCLUSIONS AND CLINICAL RELEVANCE

A strong relationship exists between increasing temperature and cell death, with a sharp increase in chondrocyte death between 50 degrees and 55 degrees C. Chondrocytes in the deepest cartilage layer are most susceptible to thermal injury. The threshold of chondrocyte recovery from thermal injury is much lower than temperatures reached during chondroplasty by use of most radiofrequency energy devices.

Treatment of grade III femoral chondral lesions: mechanical chondroplasty versus monopolar radiofrequency probe

PURPOSE

Articular cartilage defects are commonly found on the femoral condyle, and their treatment with thermal energy is thought to provide a smoother surface, sealing the damaged articular cartilage and possibly decreasing the progression of these lesions. Reports of femoral avascular necrosis (AVN) developing after bipolar thermal chondroplasty are worrisome. The purpose of this study was to compare the effects on subchondral bone and the early clinical effectiveness of mechanical shaving versus mechanical shaving plus monopolar radiofrequency (MRF) on grade III femoral chondromalacia.

TYPE OF STUDY

Randomized, prospective, controlled trial.

METHODS

In this trial 60 subjects were treated by either mechanical shaving alone (n = 30) or mechanical shaving plus MRF (n = 30). Preoperative and 12-month postoperative magnetic resonance imaging (MRI) evaluations and Tegner, Lysholm, Cincinnati, International Knee Documentation Committee, and visual analog scale assessments at 12 and 24 months were obtained.

RESULTS

Of the subjects, 56 were available for the final analysis (28 treated by shaver and 28 treated by shaver plus MRF). Baseline demographics were similar between treatment groups. Postoperative MRI findings were similar between groups, including no incidents of AVN. At a mean of 19 months postoperatively, Tegner, Lysholm, Cincinnati, International Knee Documentation Committee, and visual analog scale assessments improved significantly from pretreatment levels in both groups. No difference in mean improvement was observed between groups.

CONCLUSIONS

The primary endpoint was to look for AVN. No subchondral bone effects attributable to either mechanical shaving or radiofrequency energy were noted. The secondary endpoint was a clinical evaluation. Both groups showed significant improvements in pain and function outcomes with no discernible differences between groups. The use of monopolar radiofrequency as an adjuvant to mechanical chondroplasty with a shaver for the treatment of grade III chondral lesions did not affect MRI findings or pain and function outcomes when compared with mechanical chondroplasty by use of a shaver only.

LEVEL OF EVIDENCE

Level II, randomized controlled trial with confidence intervals not reported.

Development of partial thickness articular cartilage injury in an ovine model

The purpose of this study was to create a controlled partial thickness cartilage lesion in a sheep model, and to provide a foundation to study the natural history of the progression of this lesion. Twenty-eight sheep divided into four groups (1, 12, 24, and 52 weeks, n=7/group) were used in this study. In one stifle, a mechanical tool was used to create a 200 microm partial thickness lesion (1.5x1.5 cm2) on the medial femoral condyle via arthroscopy. Joint fluid was drawn presurgery and after euthanasia for analysis of collage II 3/4 C (long) (C2C). After euthanasia, the condyle was analyzed by gross appearance, confocal laser microscopy (CLM) for cell viability, scanning electronic microscopy (SEM) for surface roughness, Artscan for cartilage stiffness, and histology for cartilage morphology. The gross appearance of the treated area appeared rough, soft, and swollen compared to untreated control over time. CLM demonstrated that the depth of cell death increased to 590 microm at 52 weeks after surgery. SEM demonstrated that the treated area became more irregular over time. Stiffness of the treated area was significantly less than control by 12 weeks after surgery. Histologic analysis demonstrated that the 12, 24, and 52 week groups had significantly poorer histologic scores than the 1 week group. Joint fluid analysis demonstrated that the treatment group at 1 week had significant higher levels of C2C than the pretreatment baseline data. The results of this study demonstrated that partial thickness injury of cartilage continued to propagate and degenerate over time in this sheep model. Options for the prevention or treatment of this lesion may be tested using this model in the future.

Fluid temperatures during radiofrequency use in shoulder arthroscopy: a cadaveric study

Cadaveric shoulders underwent thermal capsulorrhaphy and subacromial decompression with 3 different commercially available radiofrequency (RF) devices to evaluate local and regional fluid temperatures while arthroscopic procedures were being performed. Fifteen completely thawed fresh-frozen shoulders underwent both thermal capsulorrhaphy and subacromial decompression. During thermal capsulorrhaphy, Fluoroptic mini-thermometer probes (Luxtron model 3000) were placed in the inflow bag; in the glenohumeral joint, near the inferior glenohumeral ligament; and on the RF wand. During subacromial decompression, the temperature probes were placed in the anterior and posterior subacromial space, as well as in the inflow bag and on the RF wand. All data were initially analyzed by use of analysis of variance, followed by pairwise comparison, adjusted for multiple testing by use of the Scheffé method. Mean fluid temperatures (in degrees Celsius [+/- SD]) were highest at the RF wand during both capsulorrhaphy and subacromial decompression. Mean fluid temperatures were much lower at other recorded sites. In this model, we show no deleterious elevation in arthroscopic fluid temperature while performing thermal capsulorrhaphy or subacromial decompression using any of the 3 devices at their recommended settings.

Mechanical and biochemical effect of monopolar radiofrequency energy on human articular cartilage: an in vitro study

BACKGROUND

There are growing concerns about thermal chondroplasty using radiofrequency energy to treat partial-thickness cartilage defects. However, most studies emphasize effects on chondrocyte viability, and other factors such as mechanical properties are less studied.

HYPOTHESIS

Radiofrequency energy may cause significant effects on articular cartilage other than chondrocyte viability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human osteoarthritic cartilage samples were obtained from total knee arthroplasty, and monopolar radiofrequency energy was applied using commercially available equipment. Material properties (compressive stiffness, surface roughness, and thickness) just before and after thermal treatment were determined using ultrasound. A series of biochemical analyses were also performed after explant culture of the samples.

RESULTS

The cartilage surface became smoother by radiofrequency energy, whereas cartilage stiffness or thickness was not altered significantly. Collagen fibrils, especially in the superficial layers, were converted to denatured form, whereas proteoglycan contents released in the media as well as retained in the tissue remained unchanged. The concentrations of matrix metalloproteinases (MMP-1 and MMP-2) were reduced remarkably.

CONCLUSION

Radiofrequency energy is able to create a smooth cartilage surface and reduce catabolic enzymes at the cost of collagen denaturation and chondrocyte death in the superficial layers. The stiffness of the cartilage is not changed at time zero.

CLINICAL RELEVANCE

Further animal as well as clinical studies will be necessary to fully evaluate the long-term effects of radiofrequency energy.

Glutamine protects articular chondrocytes from heat stress and NO-induced apoptosis with HSP70 expression

OBJECTIVE

To investigate the effect of l-glutamine (Gln) on stress responses of chondrocytes exposed to heat stress or nitric oxide (NO).

METHODS

Cultures of articular chondrocytes were established from rabbit joints, and treated for 12h with various concentrations of Gln (0-20 mM). In some experiments, cells were also treated with quercetin (Que), a heat shock protein 70 (HSP70) inhibitor. Heat stress (43 degrees C) was applied to the cells for 0-120 min. Apoptosis was induced by 0.5mM sodium nitroprusside (SNP) dihydrate that produces NO. After stress loading, HSP70 expression was detected by Western blot analysis. Cell viability was assessed by lactate dehydrogenase (LDH) release and tetrazolium salt-based assays, while apoptosis was evaluated by Hoechst 33342 staining, TUNEL methods and active caspase-3 determination.

RESULTS

Gln demonstrated dose-dependent enhancing effect on stress-mediated induction of HSP70, while in the absence of any stress HSP70 was not induced by Gln alone. After heating or SNP loading, chondrocytes showed severe reduction in viability, while the cytotoxic outcome was almost completely abrogated by conditioning with Gln. The protective effect of Gln was significantly blocked by Que that effectively suppressed stress-induced HSP70 expression in chondrocytes. The Gln also rendered chondrocytes unsusceptible to NO-induced apoptosis that was frequently seen in SNP-treated culture.

CONCLUSION

This study demonstrated that the treatment of chondrocytes with Gln protected the cells from heat stress and NO-induced apoptosis. These chondroprotective effects of Gln may be mediated by HSP70.

Monopolar radiofrequency treatment of partial-thickness cartilage defects in the sheep knee joint leads to extended cartilage injury

BACKGROUND

The application of radiofrequency energy to smooth and stabilize the cartilage surface has become increasingly controversial. There is little knowledge on extended-term effects, such as cartilage viability.

PURPOSE

To analyze the effect of radiofrequency treatment on artificially created partial-thickness defects in the femoral cartilage of sheep knee joints 24 weeks after surgery.

STUDY DESIGN

Controlled laboratory study.

METHODS

Grade II cartilage surface defects on the medial and lateral femoral condyles were artificially created in sheep for in vivo analysis. The cartilage lesions were treated alternately on the lateral or the medial condyle using a monopolar radiofrequency probe. Radiofrequency treatment was performed in a freehand technique until surface smoothing without change of cartilage color was seen. At 24 weeks after surgery, cartilage samples were harvested and were processed for macroscopic and histological evaluation. To analyze the effect of radiofrequency at time zero, samples of sheep femoral condyle cartilage with and without artificially created clefts were treated in vitro with radiofrequency. Evaluation was performed by scanning electron and confocal microscopy.

RESULTS

At 24 weeks after surgery, grade IV cartilage defects were detected in all radiofrequency-treated samples. The histological findings showed a central ulcer and dead chondrocytes in the radiofrequency-treated regions. The radiofrequency-treated cartilage revealed partial surface irregularities with partial-defect repair. After radiofrequency treatment in vitro, samples at time zero showed smoothing of the artificially created clefts, as seen by scanning electron microscopy. Confocal microscopy showed necrosis of chondrocytes over approximately one fourth of the upper cartilage thickness.

CONCLUSION

Even if chondrocyte death is seen only in approximately one fourth of the upper cartilage layers in the sheep femur after in vitro application, radiofrequency treatment can cause damage to cartilage 24 weeks after application.

CLINICAL RELEVANCE

Caution is recommended in the application of monopolar radiofrequency energy by visual control to partial-thickness cartilage defects. Irregular fronds of chondromalacia may be unattractive but represent viable articular cartilage. Using radiofrequency to obtain a more visually pleasing smooth surface may be counterproductive.