George Thabit

The Thermal Effect of Monopolar Radiofrequency Energy on the Properties of Joint Capsule An In Vivo Histologic Study Using a Sheep Model

The purpose of this in vivo study was to analyze the short-term tissue response of joint capsule to monopolar radiofrequency energy and to compare the effects of five power settings at 65°C on heat distribution in joint capsule. In 12 mature Hampshire sheep, the medial and lateral aspects of both stifles were treated with monopolar radiofrequency energy under arthroscopic control in a single uniform pass to the synovial surface. The radiofrequency generator power settings were 0, 10, 15, 20, 25, and 30 watts (N 8/group). The electrode tip temperature was 65°C. Histologic analysis at 7 days after surgery revealed thermal damage of capsule at all radiofrequency power settings. The lesions cross-sectional area, depth, vascularity, and inflammation were commensurate with radiofrequency power. Tissue damage was indicated by variable inflammatory cell infiltration, fusion of collagen, pyknosis of fibroblasts, myonecrosis, and vascular thrombosis, whereas synovial hyperplasia, fibroblast proliferation, and rowing of sarcolemmal nuclei demonstrated regenerative processes. This study revealed that radiofrequency power settings and heat loss through lavage solution play a significant role in heat distribution and morphologic alterations in joint capsule after arthroscopic application of monopolar radiofrequency energy.

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 non- destructively 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 en ergy 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 non ablative 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.

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.

Monopolar Radiofrequency Energy Effects on Joint Capsular Tissue: Potential Treatment for Joint Instability An In Vivo Mechanical, Morphological, and Biochemical Study Using an Ovine Model

The purpose of this study was to evaluate the thermal effect of monopolar radiofrequency energy, a potential treatment means for joint instability, on the mechanical, morphologic, and biochemical properties of joint capsular tissue in an in vivo ovine model. The energy was applied arthroscopically to the synovial surface of the femoropatellar joint capsule of 24 sheep. The sheep were sacrificed at 0, 2, 6, and 12 weeks after surgery (6 per group). Monopolar radiofrequency energy initially caused a significant decrease in tissue stiffness and an increase in tissue relaxation properties, followed by gradual improvement in the tissues mechanical properties by 6 weeks after surgery. Microscopic examination illustrated that radiofrequency energy initially caused collagen hyalinization and cell necrosis, followed by active tissue repair. Biochemical analysis revealed that treated collagen was significantly more trypsin-susceptibile than untreated collagen at 0 and 2 weeks after surgery, indicating early collagen denaturation. This study demonstrated that this treatment initially caused a significantly deleterious effect on the mechanical properties of the joint capsule, which was associated with partial denaturation of joint capsular tissue. This was followed by gradual improvement of the mechanical, morphologic, and biochemical properties of the tissue over time.

The Effect of Nonablative Laser Energy on Joint Capsular Properties An In Vitro Histologic and Biochemical Study Using a Rabbit Model

The purpose of this study was to evaluate the effect of laser energy at nonablative levels on joint capsular histologic and biochemical properties in an in vitro rabbit model. The medial and lateral portions of the femoropatellar joint capsule from both stifles of 12 mature New Zealand White rabbits were used. Speci mens were divided into three treatment groups (5 watts, 10 watts, and 15 watts) and one control group using a randomized block design. Specimens were placed in a 37° bath of lactated Ringers solution and laser energy was applied using a holmium:yttrium-alu minum-garnet laser in four transverse passes across the tissue at a velocity of 2 mm/sec with the handpiece set 1.5 mm from the synovial surface. Histologic anal ysis revealed thermal alteration of collagen (fusion) and fibroblasts (pyknosis) at all energy densities, with higher laser energy causing significantly greater mor phologic changes over a larger area (P < 0.05). Ap plication of laser energy did not significantly alter the biochemical parameters evaluated, including type I col lagen content and nonreducible crosslinks (P > 0.05). This study demonstrated that nonablative laser energy caused significant thermal damage to the joint capsular tissue in an energy-dependent fashion, but type I col lagen content and nonreducible crosslinks were not significantly altered.

The Effect of Monopolar Radiofrequency Treatment Pattern on Joint Capsular Healing In Vitro and In Vivo Studies Using an Ovine Model

The purpose of this study was to compare joint capsular healing after two delivery patterns of monopolar radiofrequency energy: 1) uniform treatment of the joint capsule (paintbrush pattern) and 2) multiple single linear passes (grid pattern). First, an in vitro study was performed to compare the percent shrinkage of these two treatment patterns using the femoropatellar joints (stifles) of six sheep. Monopolar radiofrequency energy (settings, 70°C/15W) was applied to the lateral joint capsule; the treated area was approximately 10 10 mm. There was no significant difference in shrinkage between the grid (27% 8.7%) and paintbrush (29% 7.9%) patterns. In the in vivo study, stifles of 24 sheep were randomly assigned to the paintbrush or the grid pattern groups and treatment was performed arthroscopically. Sheep were sacrificed immediately after surgery, or at 2, 6, or 12 weeks after surgery. At 6 weeks after surgery, confocal microscopy demonstrated that treated areas had almost completely repaired in the grid group; some nonviable areas were still present in the paintbrush group. Mechanical testing at 6 weeks indicated that joint capsule in the grid group had better mechanical properties than capsule in the paintbrush group. This study revealed that radiofrequency treatment of joint capsule in a grid pattern allowed faster healing than tissue treated in a paintbrush pattern.

Histologic evaluation of the glenohumeral joint capsule after the laser-assisted capsular shift procedure for glenohumeral instability.

Glenohumeral joint capsule obtained from 42 patients who had undergone an arthroscopic laser-assisted capsular shift procedure was evaluated histologically. A total of 53 samples from the anterior inferior glenohumeral ligament of the joint capsule were collected before and at various times after the procedure (range, 0 to 38 months). Despite glenohumeral instability, joint capsule of the patients before the procedure showed no significant histologic lesions. Laser treatment significantly altered the histologic properties of the tissue as evidenced by hyalinization of collagen and necrotic cells (time 0). Tissues sampled during the short-term period (3 to 6 months) after the procedure demonstrated fibrous connective tissue with reactive cells and vasculature. Collagen and cell morphology returned to normal in the middle- to long-term period (7 to 38 months) after the procedure, while the number of fibroblasts remained elevated. Joint capsule collected from the shoulders of six patients who experienced stiffness after the procedure showed persistent synovial, cellular, and vascular reaction even after 1 year postoperatively, the cause of which is unclear. This study re-

Effect of nonablative laser energy on the joint capsule: an in vivo rabbit study using a holmium:YAG laser.

The nonablative application of holmium:yttrium‐aluminum‐garnet (Ho:YAG) laser energy to the joint capsule of patients with glenohumeral instability has been found to shrink capsular tissue and to help stabilize the joint. The purpose of this study was to evaluate the effect of nonablative laser energy on the short‐term histological properties of joint capsular tissue in an in vivo rabbit model.

The mechanism of joint capsule thermal modification in an in-vitro sheep model.

The purpose of this study was to understand the mechanism responsible for joint capsule shrink-age after nonablative laser application in an in vitro sheep model. Femoropatellar joint capsular tissue specimens harvested from 20 adult sheep were treated with one of three power settings of a holmium:yttrium-aluminum-garnet laser or served as a control. Laser treatment significantly shortened the tissue and decreased tissue stiffness in all three laser groups, whereas failure strength was not altered significantly by laser treatment. Transmission electron microscopic examination showed swollen collagen fibrils and loss of membrane integrity of fibroblasts. A thermometric study revealed nonablative laser energy caused tissue temperature to rise in the range of 64° C to 100° C. Electrophoresis after trypsin digestion of the tissue revealed significant loss of distinct alpha bands of Type I collagen in laser treated samples, whereas alpha bands were present in laser treated tissue without trypsin digestion. The results of this study support the concept that the primary mechanism responsible for the effect of nonablative laser energy is thermal denaturation of collagen in joint capsular tissue associated with unwinding of the triple helical structure of the collagen molecule.

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°, 65°, 75°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° 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° C treatment groups for these three architectural parameters. Tissue temperature was elevated significantly in the laser 10 W, laser 15 W, radiofrequency 65° C, and radiofrequency 75° C groups when compared with the control. Tissue temperature changes between the laser 10 W and radiofrequency 75° 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.