Ryland B. Edwards

Thermal Chondroplasty with Radiofrequency Energy An In Vitro Comparison of Bipolar and Monopolar Radiofrequency Devices

The purpose of this study was to examine the in vitro effects of three radiofrequency energy devices (two bipolar devices and one monopolar device) for the performance of thermal chondroplasty. Thirty-two fresh bovine femoral osteochondral sections (approximately 3 4 5 cm) from eight cows were divided into four groups (three treatment patterns and one sham-operated group with eight specimens per group). The three treatment patterns consisted of 1) radiofrequency energy delivered by a mechanical jig at 1 mm/sec in a contact mode (50 g of pressure), 2) radiofrequency energy delivered by a mechanical jig at 1 mm/sec in a noncontact mode (1 mm between probe tip and articular cartilage surface), and 3) radiofrequency energy smoothing of abraded cartilage during arthroscopic visualization. Thermal smoothing of the abraded cartilage surface was accomplished with all three devices. Significant chondrocyte death, as determined by confocal laser microscopy and cell viability staining, was observed with each device. The bipolar radiofrequency systems penetrated 78% to 92% deeperthan the monopolar system. The bipolar systems penetrated to the level of the subchondral bone in all osteochondral sections during arthroscopically guided paintbrush pattern treatment. Radiofrequency energy should not be used for thermal chondroplasty until further work can establish consistent methods for limiting the depth of chondrocyte death while still achieving a smooth articular surface.

Thermal chondroplasty of chondromalacic human cartilage. An ex vivo comparison of bipolar and monopolar radiofrequency devices.

We compared the effects of treatment with bipolar and monopolar radiofrequency energy on 30 osteochondral sections harvested from 22 patients with spontaneously occurring chondromalacia who were undergoing knee arthroplasty. Specimens with chondromalacia grades 2 or 3 were randomly assigned to one of two bipolar or one monopolar treatment groups. All samples were marked and mounted on a jig to allow simulation of an arthroscopic surgical procedure with a flow rate of 100 ml/min of a balanced electrolyte solution at 22°C. Under arthroscopic visualization, the designated area was treated until smooth, and the total treatment time was recorded. There was no difference in patients’ ages, chondromalacia grade, or cartilage thickness among groups. Significant chondrocyte death, as determined by cell viability staining with confocal laser microscopy, was observed with each group. The bipolar devices produced significantly greater depths of chondrocyte death (2228 ± 1003 μm and 2810 ± 517 μm) than did the monopolar device (737 ± 391 μm). The bipolar devices caused cell death to subchondral bone significantly more often (13 of 20 specimens) than did the monopolar device (0 of 10 specimens). Caution should be used in treating fibrillated cartilage with radiofrequency energy, particularly with the bipolar devices tested.

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.

Percutaneous Injection of Recombinant Human Bone Morphogenetic Protein-2 in a Calcium Phosphate Paste Accelerates Healing of a Canine Tibial Osteotomy

BACKGROUND In this study, we evaluated the capacity of a single percutaneous injection of recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered in a rapidly resorbable calcium phosphate paste (alpha-BSM) to accelerate bone-healing in a canine tibial osteotomy model. We hypothesized that the osteotomy sites would heal faster after percutaneous delivery of rhBMP-2/alpha-BSM than they would after injection of alpha-BSM alone or after no treatment. METHODS Bilateral tibial osteotomy was performed and the sites were stabilized with external fixators in sixteen dogs. Four hours after the surgery, one limb of each dog was treated with a single percutaneous injection of rhBMP-2/alpha-BSM paste or an equal volume of alpha-BSM alone. There were eight limbs in each group, and the osteotomy site in the contralateral limb served as an untreated control. The results were evaluated with serial radiography and force-plate analysis at four and eight weeks after surgery and with mechanical testing and histologic examination at eight weeks after the surgery. RESULTS At four and eight weeks after the osteotomy and treatment, the scores for radiographic union were significantly greater for the rhBMP-2/alpha-BSM-treated limbs than they were for the alpha-BSM-treated or untreated, control limbs (p < 0.05). The callus area in the rhBMP-2/alpha-BSM-treated limbs was significantly greater than that in the alpha-BSM-treated and untreated, control limbs at four and eight weeks postinjection (p < 0.05). The time-integrated vertical force for the rhBMP-2-treated limbs was significantly greater than that for their contralateral controls at four weeks and significantly greater than that for the treated and control limbs of the alpha-BSM-treated dogs at four and eight weeks after the surgery (p </= 0.05). The rhBMP-2-treated limbs were significantly stiffer in bending and in torsion (p < 0.05) compared with the alpha-BSM-treated and control limbs. Histologic analysis demonstrated increased bone formation and more mature bone at the osteotomy site in the rhBMP-2-treated limbs compared with that in the alpha-BSM-treated and control limbs. CONCLUSIONS This study demonstrates the capacity of a single percutaneous injection of rhBMP-2 delivered in a resorbable calcium phosphate paste (alpha-BSM) four hours after surgery to accelerate the healing of tibial osteotomy sites in a canine model.

Lavage Solution Temperature Influences Depth of Chondrocyte Death and Surface Contouring During Thermal Chondroplasty with Temperature-Controlled Monopolar Radiofrequency Energy

Background: Although radiofrequency energy can smooth and contour cartilage surface, it has deleterious effects on chondrocyte viability. Hypothesis: Monopolar thermal chondroplasty in a 37°C lavage solution, as compared with a 22° lavage solution, will reduce chondrocyte death and result in greater smoothing of the articular cartilage surface. Study Design: Controlled laboratory study. Methods: Sixteen chondromalacic samples from patients undergoing total knee arthroplasty were divided into two groups: 22°C and 37°C lavage solution. Each sample was divided into two equal parts and half of each group was treated for 10 seconds and the other half for 15 seconds. Results: Confocal laser microscopy demonstrated that the depth of chondrocyte death in the 37°C lavage solution group was significantly less (range, 200 to 340 μm) than that in the 22°C solution group for both 10- and 15-second treatment times. Scanning electron microscopy demonstrated that the cartilage surface in the 37°C lavage solution group was smoother than that in the 22°C solution group for the 10-second treatment time. Energy delivery power in the 37°C lavage solution group was significantly lower than in the 22°C solution group for both treatment times. Conclusions: Thermal chondroplasty with 37°C lavage solution resulted in less depth of chondrocyte death and produced smoother surfaces than with 22°C solution for 10 seconds of treatment. Clinical Relevance: Less chondrocyte death would permit increased use of thermal chondroplasty.

Histomorphometric description of allograft bone remodeling and union in a canine segmental femoral defect model: A comparison of rhBMP-2, cancellous bone graft, and absorbable collagen sponge

The purpose of this study was to determine the effect of recombinant human bone morphogenetic protein type 2 (rhBMP‐2) on the histomorphometry of femoral allograft‐host bone union and allograft remodeling. A 6 cm mid‐diaphyseal femoral defect was created and filled with an allograft stabilized with an interlocking nail in 21 dogs. Dogs were randomly divided into three equal groups and the allograft‐host bone junctions and the mid‐diaphyses of the allografts were treated with either an absorbable collagen sponge (ACS) loaded with rhBMP‐2 (BMP group), an autogenous cancellous bone graft (CBG group), or ACS loaded with buffer solution (ACS group). All dogs received daily tetracycline until sacrifice at 24 weeks to label new bone formation. Histomorphometric analyses on sections of proximal and distal allograft‐host bone junctions and the mid‐diaphyseal portion of allografts were performed using fluorescent and regular light microscopy. Analyses of the host bone and junctions between allograft and host bone revealed significantly greater new bone formation and larger osteon radii in the BMP group compared to CBG and ACS groups and contralateral intact bone. Porosity in CBG and ACS groups was significantly higher than in the BMP group, which had similar values to intact bone. In transverse sections of allografts, the largest pore diameters were present in the CBG group. Based on all parameters measured, significantly higher bone turnover occurred in the outer cortical area of the allograft in all groups as compared to the inner cortical and mid‐cortical areas. New bone formation and osteon radius/osteon width in allografts were similar for all three groups. Higher porosity and larger pore diameters in the CBG and ACS groups suggested higher bone resorption versus formation in these groups compared to the BMP group. The results of this study reveal more balanced allograft bone resorption and bone formation in the BMP group, with greater resorptive activity in the CBG and ACS groups. However, neither rhBMP‐2 nor autogenous bone graft increased allograft incorporation when compared to the negative control (ACS group).

Comparison of radiofrequency treatment and mechanical debridement of fibrillated cartilage in an equine model

OBJECTIVE To compare a radiofrequency energy (RFE) prototype probe to mechanical debridement (MD) and a commercially available RFE system used for chondroplasty in the treatment of an experimentally created partial thickness cartilage lesion in horses. The study design was experimental, randomized complete block, n=8, using fifteen mature ponies. METHODS Grade 2 to 3 cartilage lesions were prepared in both patellae. After 10 months duration, the injuries were used to study the effects of MD, a commercially available bipolar RFE device (CoVac 50; ArthroCare Corporation) and a prototype monopolar RFE device (Smith & Nephew Endoscopy). Six months after treatment the patellae were examined for chondrocyte viability and cartilage structure. RESULTS Mean depth of cell death was significantly different among groups (controls, MD <prototype<CoVac 50) (P<0.05). Total histologic scores did not demonstrate any significant differences among the controls, MD and prototype RFE groups, which were all better than the CoVac 50 scores (P<0.05). There was a trend for the prototype RFE probe treated regions to have better surface structural characteristics than MD (P=0.11). Cartilage thickness was greater for the prototype RFE group than all other groups, and was the thinnest for the CoVac 50 group (P<0.05). CONCLUSION When thermal chondroplasty is performed with a power-controlled prototype RFE probe, there is a better surface smoothing effect compared to MD, which causes less chondrocyte death and has the potential to maintain thicker cartilage compared to the commercially available RFE system.

The basic science of thermally assisted chondroplasty

Thermal chondroplasty provides a visually enticing effect on articular cartilage, but the long-term effects of thermal modification and injury to articular cartilage must be understood before the technology is applied to cartilage and chondrocytes in a clinical setting.

Radiofrequency energy treatment effects on articular cartilage

Partial-thickness cartilage erosion and fibrillation is commonly encountered during arthroscopic examination. These changes may occur secondary to acute injury or as a result of slow degenerative changes associated with aging. Unfortunately, no one technique has the versatility to allow the orthopaedic surgeon to debride partial-thickness lesions, prevent their recurrence, and halt their progression. Historically, radiofrequency energy (RFE) has been used in the fields of neurosurgery, oncology, cardiology, and, more recently, in musculoskeletal surgery for arthroscopic capsulorrhaphy procedures. RFE has the advantages of being safe, relatively inexpensive, and easy to use via arthroscopy. In addition, at least 5 major manufacturers now provide an array of probes designed for arthroscopic application. Although the effects of RFE on the joint capsule are well documented through controlled research, there are few reports on its effects on articular cartilage and those reports that are present in the peer-reviewed literature provide conflicting information. RFE can rapidly contour and smooth fine fibrillations associated with chondromalacic cartilage, but it does not appear to be a tool that can be used safely for ablating larger fronds (>1.0 mm) and stabilizing delaminated areas. Bipolar probes, at recommended settings, operate at temperatures in excess of 100°C, often result in rapid chondrocyte death to depths greater than 2.0 mm from the articular surface, and should not be used for thermal chondroplasty. RFE with temperature control, though far safer than bipolar RFE, kills cells to a depth of approximately 0.75 mm and further evaluation of its safety and long-term efficacy should be performed before it can be recommended for clinical use. Although anecdotal reports indicate that RFE may have application for performing thermal chondroplasty, further in vitro and in vivo studies are required to determine the optimal settings and guidelines for its use.

Surgical findings and outcome for dairy cattle with jejunal hemorrhage syndrome: 31 cases (2000-2007).

OBJECTIVE To describe signalment; surgical findings; short-, medium-, and long-term outcome; and recurrence rate for cattle undergoing celiotomy because of jejunal hemorrhage syndrome (JHS) and to analyze risk factors associated with outcome and recurrence. DESIGN Retrospective case series. ANIMALS 31 dairy cattle with JHS. PROCEDURES Medical records were analyzed. Follow-up information was obtained from owners of cattle surviving until discharge. RESULTS 18 of 31 (58%) cattle undergoing celiotomy survived to initial discharge. Fifteen (48%) and 13 (42%) were alive 6 and 12 months after discharge, respectively. All 5 deaths within 12 months after discharge were attributed to JHS recurrence. Survival time was 12 to 85 months for the 13 long-term survivors. Six of 7 that died > 12 months after celiotomy did so for reasons unrelated to JHS. Recurrence rate among short-term survivors was 7 of 18; 1 of these survived long-term. A significant proportion of affected cattle were Brown Swiss, compared with proportions for other breeds. Manual massage of the bowel to break down clots was associated with a significantly higher short-term survival rate than was enterectomy or enterotomy. Medium- and long-term survival rate was higher in cattle referred 24 to 48 hours after onset of signs. Length of obstructing blood clots was not associated with outcome. Other factors were not significantly associated with recurrence. CONCLUSIONS AND CLINICAL RELEVANCE Survival rates were higher than those in other reports. Prompt celiotomy and resolution by use of manual massage were associated with higher survival rates. In this population, JHS recurred in 7 of 18 short-term survivors.