Subacromial temperature profile during bipolar radiofrequency use in shoulder arthroscopy. Comparison of Coblation® vs. VAPR®.

BACKGROUND: The use of bipolar electrodes for arthroscopic procedures carries a theoretical ex vivo risk of inducing burn injuries. Few studies have measured the in vivo temperatures produced by bipolar electrodes during arthroscopy, and their results are conflicting. The objective of this study was to evaluate the temperature profile within the subacromial space during shoulder arthroscopy with two different electrode systems. HYPOTHESIS: The primary hypothesis was that the two electrode systems produced similar temperature variations and peak temperatures. The secondary hypothesis was that neither electrode system produced irrigation-fluid temperatures above the tissue-damage threshold. MATERIAL AND METHODS: A comparative, prospective, single-centre, single-surgeon, single-blind study was conducted to compare the Coblation® system (Smith&Nephew, Andover, MA, USA) and the VAPR® system (DePuy Synthes Mitek Sports Medicine, Raynham, MA, USA) in 13 patients undergoing shoulder arthroscopy. A temperature probe inserted into the subacromial space was used to record temperatures at 10-second intervals for 60seconds during continuous radiofrequency application. RESULTS: Mean baseline temperature was 21.4±0.7°C with VAPR® and 23.0±2.2°C with Coblation®. No significant between-group differences were found during the first 40seconds. The mean peak temperature reached after 60seconds was 25.0±1.9°C with VAPR® and 27.9±2.8°C with Coblation® (P<0.05). DISCUSSION: Few studies have compared the in vivo temperatures produced during arthroscopy by different electrode systems. In vivo studies have established that temperature increases can cause tissue damage, particularly to chondrocytes, and that the irrigation flow rate plays a key role in lowering the in vivo temperatures. Our study showed a significant difference between the two electrode systems after 50seconds of use, with lower temperatures with the VAPR®. Nevertheless, neither system increased the irrigation-fluid temperatures above the tissue-damage threshold. Both systems can be used safely, provided the manufacturer instructions are followed and the irrigation system is effective. LEVEL OF EVIDENCE: II (prospective randomized trial).

Radiofrequency energy on cortical bone and soft tissue: a pilot study.

BACKGROUND: Radiofrequency-generating energy devices have been used clinically in musculoskeletal procedures to provide hemostasis and capsular shrinkage (thermal capsulorrhaphy). However, the dose-effects are not well known. QUESTIONS/PURPOSES: We therefore determined dosage effects of radiofrequency energy on bone, skin incisions, and joint capsule in sheep. METHODS: Five mature sheep had six 2.5-cm(2) tibial periosteal defects and six 1.0-cm skin incisions assigned to six treatments varying by watts and fluence (f = watts . seconds/cm(2)): (1) untreated control, (2) 50 W for 9.5 seconds (190f; n = 5), (3) 110 W for 4.3 seconds (190f; n = 5), (4) 170 W for 2.8 seconds (190f; n = 5), (5) 170 W for 5.6 seconds (380f; n = 5), or (6) 170 W for 8.4 seconds (570f; n = 5). Outcomes included hemostasis, contraction, healing, and histomorphometry for inflammation and necrosis at 2 weeks. RESULTS: Radiofrequency energy application on skin at 190f or greater had more than 80% hemostasis and dose-dependent contraction, inflammation, and necrosis. Radiofrequency energy application on bone had good (70%) hemostasis at 190f and complete (> 95%) hemostasis at 380f and 570f, without histologic or clinically detectable necrosis. CONCLUSIONS: Hemostasis can be achieved with radiofrequency energy at 190f in skin and bone. Bone necrosis was not detected at up to 570f. Using fluence greater than 190f in skin achieved dose-dependent necrosis and incisional contraction. CLINICAL RELEVANCE: Radiofrequency energy can be used on bone and skin for hemostasis, but potential incisional complications, such as necrosis and an atypical firm and desiccated surface, should be expected.

Effect of radiofrequency energy on glenohumeral fluid temperature during shoulder arthroscopy.

BACKGROUND: Reports of glenohumeral chondrolysis following arthroscopy have raised concern about the deleterious effects that thermal devices may have on articular cartilage. The purpose of this study was to investigate the effects of flow and duration of treatment with a thermal device on temperatures within cadaveric glenohumeral joint specimens. It was hypothesized that the use of a thermal device during surgery increases the temperature of fluid within the joint to >45 degrees C, which has been shown to cause chondrocyte death. METHODS: Temperature was measured at four locations within ten cadaver shoulder joints. Eight heating trials were performed on each cadaver shoulder to test three variables: the method of heating (continuous or intermittent), the fluid-pump flow rate (no flow, 50% flow, or 100% flow), and the location of the radiofrequency probe (the radiofrequency energy was either applied directly to anterior capsular tissue in a paintbrush pattern or held adjacent to the glenoid without tissue contact). RESULTS: Temperatures of >45 degrees C occurred in every trial. The average maximum temperatures in all no-flow conditions were significantly higher than those in the trials with flow. Higher temperatures were measured by the anterior probe in all trials. When the heating had been applied adjacent to the glenoid, without tissue contact, the time needed to cool to a safe temperature was significantly longer in the no-flow states (average, 140.5 seconds) than it was in the 50% flow states (average, 12.5 seconds) or the 100% flow states (average, 8.5 seconds). CONCLUSIONS: Use of a thermal probe during arthroscopy may cause joint fluid temperatures to reach levels high enough to cause chondrocyte death. Maintaining adequate fluid-pump flow rates may help to lower joint fluid temperatures and protect articular cartilage.

The use of radiofrequency energy during arthroscopic surgery and its effects on intraarticular tissues.

The use of radiofrequency (RF) energy has become very popular in human and veterinary arthroscopic surgery since the late 1990s. Both monopolar and bipolar RF units are available. Application of RF energy to joint capsular tissue leads to immediate tissue shrinkage that is both power and temperature dependent. Changes in joint capsular tissue have been noted at temperatures greater than 65 degrees C. Treatment of articular cartilage with RF energy leads to immediate chondrocyte damage. This damage is also power and temperature dependent and is observed at temperatures as low as 45 degrees C. Caution should be used when applying RF energy within a joint to prevent or minimize articular cartilage injury.

Safety and efficacy of ultraviolet-a light-activated gene transduction for gene therapy of articular cartilage defects.

BACKGROUND: Gene therapies for articular cartilage defects are limited by the absence of an in vivo delivery system that can mediate site-specific transduction restricted to within the margins of the defect during routine arthroscopy. We have proposed the use of ultraviolet light to stimulate gene expression following infection by recombinant adeno-associated virus (rAAV). However, research has demonstrated that short-wavelength ultraviolet light (ultraviolet C), while effective, is neither safe nor practical for this purpose. We evaluated the safety and efficacy of long-wavelength ultraviolet light (ultraviolet A) from a laser to induce light-activated gene transduction in articular chondrocytes in vitro and in vivo. METHODS: The effects of ultraviolet A from a 325-nm helium-cadmium laser, delivered through a fiberoptic cable, on cytotoxicity, mutagenesis, intracellular reactive oxygen species, and light-activated gene transduction of human articular chondrocytes were evaluated in dose-response experiments of primary cultures. Cytotoxicity was determined by trypan blue exclusion. The presence of pyrimidine dimers in purified genomic DNA was determined by enzyme-linked immunosorbent assays. Intracellular reactive oxygen species levels were determined by flow cytometry at one hour and twenty-four hours. In vitro light-activated gene transduction with rAAV vectors expressing the green fluorescent protein (eGFP) or beta-galactosidase (LacZ) was determined by fluorescence microscopy and bioluminescence assays, respectively. In vivo light-activated gene transduction was quantified by stereotactic immunohistochemistry for beta-galactosidase in rabbit articular cartilage defects in the patellar groove that had been irradiated with +/-6000 J/m2 of ultraviolet A one week after direct injection of 10(7) transducing units of rAAV-eGFP. RESULTS: Ultraviolet A failed to induce significant cytotoxicity at all fluencies below 6000 J/m2. Dose-dependent cytotoxicity was observed at greater fluencies. In contrast to ultraviolet C, which induced significant (p < 0.05) pyrimidine dimer formation at all fluencies in a dose-dependent manner, ultraviolet A failed to induce DNA modifications. Conversely, ultraviolet C proved to be a poor inducer of intracellular reactive oxygen species, while ultraviolet A immediately induced high levels of intracellular reactive oxygen species, which were completely resolved twenty-four hours later. Ultraviolet A demonstrated significant light-activated gene transduction effects in vitro, which were dose-dependent (p < 0.05). In vivo, ultraviolet A mediated a tenfold increase in transduction in which 40.8% of the superficial chondrocytes adjacent to the defect stained positive for green fluorescent protein compared with 5.2% in the knees treated with no ultraviolet A (p < 0.006). CONCLUSIONS: These results provide what we believe is the first formal demonstration of an agent that can induce rAAV transduction in the complete absence of cytotoxicity and DNA modification. They also suggest that the mechanism by which long-wavelength ultraviolet light mediates site-specific gene expression is by means of the induction of intracellular reactive oxygen species. Finally, laser-derived ultraviolet A can be readily transferred through a fiberoptic cable to mediate light-activated gene transduction in vivo.

Radiofrequency energy effects on the mechanical properties of tendon and capsule.

PURPOSE: To compare the mechanical properties of tendon and capsule after radiofrequency (RF) energy treatment. TYPE OF STUDY: An in vitro study. METHODS: RF energy was applied to ovine extensor tendon and human cadaveric glenohumeral capsule varying in the treatment wattage and time (5, 10, or 20 W for 10 or 30 seconds). The associated tissue length changes and dynamic and failure properties of the tissues were investigated using a materials testing machine. RESULTS: Length changes in the 2 tissues were comparable across the range of treatment settings used with both increases in the treatment wattage and time increasing the amount of tissue shrinkage observed. However, tendon showed greater changes in its mechanical properties after RF treatment, with significant decreases in the failure properties of the tissue as well as the dynamic and static stiffness. CONCLUSIONS: RF treatment shrinks collagenous tissues in a progressive manner correlated to the treatment wattage. However, it has different effects on the mechanical properties of tendon and capsule with the properties of tendinous tissues dramatically reduced. CLINICAL RELEVANCE: RF treatment has been shown to effect the mechanical properties of different collagenous tissues differently; therefore, it must be used specifically and with caution around areas of mixed tissue origin.

Effect of simulated shoulder thermal capsulorrhaphy using radiofrequency energy on glenohumeral fluid temperature.

PURPOSE: To determine joint fluid temperatures at different time intervals during treatment with radiofrequency energy (RFE) applied in intermittent and continuous treatment manners under flow or no-flow conditions using a simulated shoulder joint model. TYPE OF STUDY: In vitro measurement of simulated joint fluid temperature during RFE treatment. METHODS: A custom-built jig with a chamber (volume size, 25 mL) was used to mimic the adult human shoulder. Three RFE systems: Vulcan EAS plus TAC-S probe (Smith & Nephew Endoscopy, Andover, MA); VAPR II plus End-Effect Electrode (Mitek, Westwood, MA); and ArthroCare 2000 plus TurboVac 90 degrees probe (ArthroCare, Sunnyvale, CA) were tested in the chamber with saline solution initially set at 23 degrees C. Each RFE probe was applied in a paintbrush pattern on the capsular tissue in the chamber and a fluoroptic thermometry probe was placed 1 cm above the RFE treatment probe to record the fluid temperature. Both intermittent and the continuous treatment manners were tested under flow and no-flow conditions. For each probe/manner/flow combination, 6 bovine capsular tissue specimens were tested (n = 6). All data were recorded using a HyperTerminal software program (Hilgraeve Inc, Monroe, MI) into a personal computer. RESULTS: When using intermittent and continuous treatment manners with flow, all recorded chamber fluid temperatures for all tested RFE probes at each time interval were below 40 degrees C. Under no-flow conditions, with intermittent treatment, the ArthroCare probe caused joint fluid temperatures to exceed 50 degrees C after 70 seconds of RFE treatment. With the continuous treatment, the ArthroCare caused chamber fluid temperatures to exceed 65 degrees C after 2 minutes of treatment. The highest mean recorded chamber fluid temperature was caused by ArthroCare probe, which reached 80 degrees C at 3 minutes. For all probes, continuous treatment caused significantly higher chamber fluid temperatures than intermittent treatment. CONCLUSIONS: The results of this study indicate that using flow during thermal capsulorrhaphy could lower joint fluid temperature to prevent heated joint fluid from killing chondrocytes of articular cartilage, and the intermittent treatment manner caused lower fluid temperature compared with continuous treatment within the RFE-treated shoulder joint. CLINICAL RELEVANCE: Articular cartilage of the humeral head may suffer potential thermal injury from heating of joint fluid during RFE thermal capsulorrhaphy.

A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders.

We investigated if low level laser therapy (LLLT) of the joint capsule can reduce pain in chronic joint disorders. A literature search identified 88 randomised controlled trials, of which 20 trials included patients with chronic joint disorders. Six trials were excluded for not irradiating the joint capsule. Three trials used doses lower than a dose range nominated a priori for reducing inflammation in the joint capsule. These trials found no significant difference between active and placebo treatments. The remaining 11 trials including 565 patients were of acceptable methodological quality with an average PEDro score of 6.9 (range 5-9). In these trials, LLLT within the suggested dose range was administered to the knee, temporomandibular or zygapophyseal joints. The results showed a mean weighted difference in change of pain on VAS of 29.8 mm (95% CI, 18.9 to 40.7) in favour of the active LLLT groups. Global health status improved for more patients in the active LLLT groups ( relative risk of 0.52; 95% CI 0.36 to 0.76). Low level laser therapy with the suggested dose range significantly reduces pain and improves health status in chronic joint disorders, but the heterogeneity in patient samples, treatment procedures and trial design calls for cautious interpretation of the results.

Ablation of bone, cartilage, and facet joint capsule using Ho:YAG laser.

OBJECTIVE: The objective of this study was to determine of the efficiency of holmium:YAG laser for bone ablation, compared to cartilage and soft tissue of the intervertebral foramen of the lumbosacral spine. BACKGROUND DATA: The holmium:YAG (Ho:YAG) laser has been used for ablation of bulging or prolapsed discs and also has the potential for decompression of the nerve root when there is narrowing of the foraminae (foraminoplasty). It is proposed that laser ablation of bone and ligament of the intervertebral foramen for nerve root decompression using the Ho:YAG laser is able to produce sufficient bone ablation without inducing significant thermal necrosis in surrounding tissues due to its short absorption length, which could result in significant clinical advantages. MATERIALS AND METHODS: Experiments were performed on samples of laminar bone, facet joint capsule, and cartilage for quantitative and qualitative determination of the effect of Ho:YAG ablation on tissue mass loss using a range of pulse energies from 0.5 to 1.5 J/P at 15 pulses/sec. RESULTS: The results showed a significant linear correlation between the mass loss and pulse energy, and between the mass loss and radiant exposure. Electron microscopy and histology showed that the Ho:YAG ablation resulted in a very sharp and clear border with little charring. Applying 0.01 k.J of total energy at two different settings (1.5 J/p, high power, and 0.5 J/p, low power) at 15 pulses/sec, the cross-sectional area/mm(2) of the ablated bone was measured, using light microscopy and the Scion Image analysis program. The ablated areas were 2.28 +/- 0.87 and 1.16 +/- 0.43 mm(2) at high and low power, respectively (p = 0.008).

Radiofrequency energy induced heating of bovine capsular tissue: in vitro assessment of newly developed, temperature-controlled monopolar and bipolar radiofrequency electrodes.

This in vitro investigation characterized temperature changes associated with radiofrequency (RF) energy induced heating of bovine capsular tissue using newly developed, temperature-controlled monopolar (Vulcan RF system and Vulcan, TAC-S Electrothermal Probe) and bipolar (VAPR II RF system and VAPR TC RF electrode) RF systems and electrodes. Bovine capsular tissue samples were placed in a saline bath maintained at room temperature. Both RF generators were used at settings of 75 degrees C and 40 W. The RF electrodes were placed in stationary positions on the tissue samples and activated for 1- to 10-s. A fluoroptic thermometry system was utilized to record temperatures at the RF electrode-tissue interface at 1-s intervals. The results indicated that the mean tissue temperatures for the monopolar RF electrode tended to be higher than those produced by the bipolar RF electrode, especially during the 2- to 10-s RF delivery time intervals (P<0.05). Notably, during the 2- to 10-s time intervals the monopolar RF electrode produced mean tissue temperatures that exceeded the set temperature of 75 degrees C (range of differences +1.2 to +15.7 degrees C highest mean temperature 90.7 degrees C). By comparison, the bipolar RF electrode maintained tissue temperatures relatively close to the set temperature(range of differences -3.2 to +2.7 degrees C; highest mean temperature 77.7 degrees C). These findings provide basic temperature profiles for the two new temperature-controlled RF devices.

Thermal-assisted capsular modification for functional ankle instability.

Chronic symptoms following lateral ankle sprain occasionally requires surgical intervention. Many options are available including thermal assisted capsular modification. The authors review the history of thermal modification of tissues, the indication for use in the ankle and report their experience with a consecutive case series over a one year period.

Radiofrequency energy-induced heating of bovine capsular tissue: Temperature changes produced by bipolar versus monopolar electrodes.

PURPOSE: To determine temperature changes associated with radiofrequency (RF) energy-induced heating of bovine capsular tissue using a bipolar RF electrode versus a temperature-controlled, monopolar RF electrode. TYPE OF STUDY: In vitro laboratory investigation using bovine capsular tissue. METHODS: Samples of bovine tissue were placed in a saline bath (37 degrees C) and RF energy was applied using bipolar and monopolar RF electrodes at manufacturer-recommended settings for tissue shrinkage. Fluoroptic thermometry was used to record temperatures on the tissue surface and at depths of 1 mm and 2 mm during continuous delivery of RF energy at 1, 2, 3, 4, 5, and 10 second time increments. RESULTS: The highest mean temperatures were recorded on the tissue surface, as follows (mean +/- SD; *P <.05, value compared with baseline): 1 sec 2 sec 3 sec 4 sec 5 sec 10 sec Bipolar 40.1 +/- 1.0* 48.2 +/- 4.7* 62.8 +/- 6.9* 76.0 +/- 7.6* 84.7 +/- 5.7* 94.7 +/- 1.9* Monopolar 39.0 +/- 0.7* 48.2 +/- 4.3* 67.7 +/- 7.0* 86.6 +/- 6.1* 93.8 +/- 2.7* 59.5 +/- 2.6* For the bipolar RF electrode, there was a strong linear relationship (R =.926) between mean surface temperatures versus time. The temperature-controlled, monopolar RF electrode did not appear to properly regulate the delivery of RF energy to maintain tissue temperatures at the selected level (i.e., 65 degrees C). The bipolar RF electrode produced a smaller temperature gradient (average difference, 9.2 degrees C) at the 1-mm tissue depth compared with the monopolar RF electrode (average difference, 14.6 degrees C). Temperature profiles at the 2-mm tissue depth were comparable for both types of RF electrodes. CONCLUSIONS: These data provide basic information pertaining to the temperature profiles produced by bipolar and monopolar RF electrodes applied to collagen-based tissue.

Thermally induced shrinkage of joint capsule.

Thermal shrinkage of collagen currently is being used in orthopaedic surgery to treat ligamentous laxity. Understanding the kinetics of collagen shrinkage is key to revealing the events that take place during application of thermal energy. To elucidate the thermokinetic properties of collagen, punch biopsies of bovine joint capsule were immersed in a heated saline bath at temperatures between 20 degrees and 90 degrees C for periods up to 60 minutes. The resulting tissue thermal shrinkage was measured by the change in the cross-sectional area of the specimens. Only a small amount of shrinkage occurred at temperatures below 63 degrees C, and increasing amounts and rates of shrinkage were seen at temperatures between 63 degrees and 72 degrees C. The denaturation kinetics of bovine knee collagen, which could be described by a first order reaction rate, had an activation energy of 2.3 x 10(5) kJ/mol.

Comparative effects of laser and radiofrequency energy on joint capsule.

The study compared the effects of laser and monopolar radiofrequency energy on thermal and architectural properties of joint capsular tissue in an in vitro ovine model. Sheep glenohumeral joint capsular specimens were treated with laser (5, 10, 15 W) or radiofrequency energy (55 degrees, 65 degrees, 75 degrees C) (n = six per group). Energy application caused significant tissue shrinkage and decreased surface area in all laser and radiofrequency treatment groups. Tissue thickness significantly increased in all treatment groups except for radiofrequency 55 degrees C. Tissue shrinkage, surface area, and thickness each correlated significantly with the delivered laser energy per tissue area or mean radiofrequency probe temperature. There were no significant differences among laser 10 W, laser 15 W, and radiofrequency 75 degrees C treatment groups for these three architectural parameters. Tissue temperature was elevated significantly in the laser 10 W, laser 15 W, radiofrequency 65 degrees C, and radiofrequency 75 degrees C groups when compared with the control. Tissue temperature changes between the laser 10 W and radiofrequency 75 degrees C groups were similar; however, laser treatment produced a steeper temperature increase accompanying its peak temperature. Despite different mechanisms, laser and radiofrequency energy can achieve similar and predictable tissue modification, which is temperature dependent. Additional in vivo studies must be performed to evaluate the applicability of these techniques to clinical use.

The effect of radiofrequency energy on the ultrastructure of joint capsular collagen.

This study evaluated the effect of radiofrequency energy on the histological and ultrastructural appearance of joint capsular collagen. Femoropatellar joint capsular specimens from adult sheep were treated with one of three treatment temperatures (45 degrees C, 65 degrees C, and 85 degrees C) with a radiofrequency generator or served as control in a randomized block design. Twenty-four specimens (n = 6) were processed for histological examination as well as ultrastructural analysis using transmission electron microscopy. A computer-based area determination program was used to calculate the area affected in histological samples. Histological changes consisted of thermal tissue damage characterized by collagen fiber fusion and fibroblastic nuclear pyknosis at all application temperatures with clear demarcations between treated and untreated tissue. Mean tissue affected ranged from 50.4% for 85 degrees C to 22.5% for 45 degrees C. There was a strong correlation between treatment temperature and percent area affected (P < .001, R2 = .65). Ultrastructural alterations included a general increase in cross-sectional fibril diameter and loss of fibril size variation with increasing treatment temperature. Longitudinal sections of collagen fibrils showed increased fibril diameter and the loss of cross-striations in the treated groups. Thermally induced ultrastructural collagen fibril alteration is likely the predominant mechanism of tissue shrinkage caused by application of radiofrequency energy.

The effect of nonablative laser energy on the ultrastructure of joint capsular collagen.

This study was designed to evaluate the effect of laser energy at nonablative levels on the ultrastructure of joint capsular collagen. The femoropatellar joint capsules of six mature New Zealand white rabbits were harvested immediately after death. Specimens were divided into three treatment groups (5, 10, and 15 watts) and one control group. Laser energy was applied using a holmium: YAG laser. Transmission electron microscopy showed significant ultrastructural alterations in collagenous architecture for all laser treatment groups, with increased fibril cross-sectional diameter for each of the treated groups. The fibrils began to lose their distinct edges and their periodical cross-striations at subsequently higher energy densities. A morphometric analysis showed that each subsequently higher laser energy caused a significant increase in collagen fibril diameter. Ultrastructural alteration of collagen fibril architecture caused by the thermal effect of laser energy is probably the dominant mechanism of laser-induced tissue shrinkage.

The effect of nonablative laser energy on joint capsular properties. An in vitro mechanical study using a rabbit model.

To evaluate the effect of laser energy at nonablative levels on the mechanical properties of joint capsular tissues, we tested the femoropatellar joint capsules of 12 mature New Zealand White rabbits. Specimens were divided into three treatment groups (5, 10, and 15 watts) and one control group. All specimens were first nondestructively mechanically tested to determine stiffness and viscoelastic properties and then treated with laser energy or served as a control. Shrinkage was recorded and mechanical testing was repeated. The application of laser energy resulted in 9%, 26%, and 38% reduction in capsular tissue length for the 5, 10, and 15 watt groups, respectively. Tissue shrinkage was significantly and strongly correlated with energy density. Laser energy caused a significant decrease in tensile stiffness only in the 10 and 15 watt groups. Laser energy did not change the relaxation properties at any energy density. This study demonstrates that significant capsular shrinkage can be achieved with the application of nonablative laser energy without detrimental effects to the viscoelastic properties of the tissue; although at higher energy densities, laser energy did lessen capsular stiffness properties. The results of this study should be interpreted with caution until in vivo studies are performed.