Ultrasonic incisions produce less inflammatory mediator response during early healing than electrosurgical incisions.

As the use of laparoscopic surgery has become more widespread in recent years, the need has increased for minimally-invasive surgical devices that effectively cut and coagulate tissue with reduced tissue trauma. Although electrosurgery (ES) has been used for many generations, newly-developed ultrasonic devices (HARMONIC® Blade, HB) have been shown at a macroscopic level to offer better coagulation with less thermally-induced tissue damage. We sought to understand the differences between ES and HB at a microscopic level by comparing mRNA transcript and protein responses at the 3-day timepoint to incisions made by the devices in subcutaneous fat tissue in a porcine model. Samples were also assessed via histological examination. ES-incised tissue had more than twice as many differentially-expressed genes as HB (2,548 vs 1,264 respectively), and more differentially-expressed proteins (508 vs 432) compared to control (untreated) tissue. Evaluation of molecular functions using Gene Ontology showed that gene expression changes for the energized devices reflected the start of wound healing, including immune response and inflammation, while protein expression showed a slightly earlier stage, with some remnants of hemostasis. For both transcripts and proteins, ES exhibited a greater response than HB, especially in inflammatory mediators. These findings were in qualitative agreement with histological results. This study has shown that transcriptomics and proteomics can monitor the wound healing response following surgery and can differentiate between surgical devices. In agreement with clinical observations, electrosurgery was shown to incur a greater inflammatory immune response than an ultrasonic device during initial iatrogenic wound healing.

Perpendicular blood vessel seals are stronger than those made at an angle.

Vessel sealing devices effectively produce hemostatic seals with minimal thermal damage, but the strength of seals decreases as vessel diameter increases. Because vessels sealed at an angle to the vessel require a greater functional seal diameter than those sealed perpendicularly to the vessel, it was hypothesized that perpendicular seals would have comparably higher burst pressures. Ex vivo, porcine carotid arteries of nominal diameters of 5, 6, and 7 mm were sealed perpendicularly to and at a 45° angle to the longitudinal axis of the vessels, and burst pressures of the sealed vessels were measured. Overall burst pressures were 51% greater for perpendicular seals than for angled seals (P<.001). Mean burst pressures for the 5-mm angled and 7-mm perpendicular groups, which have similar seal lengths, were not significantly different (P=.959). Analysis using the functional diameter as a covariate indicated that the seal length is the primary variable in determining burst pressure, and not some other inherent characteristic of angled versus perpendicular sealing. These results suggest that at least for vessels ≥5 mm in diameter, surgeons should approach vessels perpendicularly and not at an angle, for the highest possible seal strength. The development of articulated sealing and cutting devices would provide greater seal strength, in addition to improved maneuverability, especially in laparoscopic surgery, where angles of approach may be limited by the fixed location of surface cannulas.

Electromagnetic energy sources in surgery.

The biophysics, mechanism of actions, applications, benefits and complications of electromagnetic (EM) energy-based surgical instruments, and their current use are reviewed. Understanding the mechanism of action, tissue effects, and appropriate applications of EM devices is critical to achieving an optimal surgical outcome. Although a more diverse range of EM devices are used in human medicine, current use in veterinary medicine is limited to conventional electrosurgery and CO(2) lasers.

Can harmonic focus curved shear effectively seal the pancreatic ducts and prevent pancreatic leak? Feasibility evaluation and testing in ex vivo and in vivo porcine models.

BACKGROUND: The purpose of this study was to evaluate the ability of Harmonic energy technology to transect and seal the pancreatic duct compared with the standard monopolar electrosurgery transection and oversew technique in a porcine distal pancreatectomy survival model. Harmonic energy technology is as effective as standard oversew technique for preventing pancreatic leak after distal pancreatectomy. METHODS: The animal protocol used for this study was approved by the Institutional Animal Care and Use Committee (IACUC) prior to the conduct of the study. Spleen-preserving distal pancreatectomy was performed in seven pigs (80-100 lb) by the same surgeon. In four animals, the pancreas was divided with the Harmonic Focus Curved Shears (test group) with no additional suturing for control of hemostasis or leak. In three animals, the pancreas was divided using monopolar electrosurgery (30 W coagulation) and the cut end of the pancreas was oversewn with a locking suture (control group). A previously worked out standard operative technique was used in all procedures. Operating end points included surgery time and blood loss. Animals were euthanized and necropsied at 7 to 8 d following surgery. Survival endpoints included clinical response to surgery, serum chemistry profiles before surgery and at necropsy, and histology of the pancreas transection site. RESULTS: Mean operative time for pancreatic resection was 15min in the control group and 10min in the test group. No significant blood loss was noted in either group. The median size of the resected pancreas was 4.3 cm. Three animals in the control group and three in the test group completed the study without complications. One animal in the test group failed to eat, appeared dehydrated, and was taken off study on POD#2. In this animal, there was a doubling of serum lipase at euthanasia and gross evidence of ileus, which was attributed to a pancreatic leak. Histologic examination of the residual pancreas in both groups at necropsy revealed a 2-5 mm band of necrotic tissue associated with neutrophilic infiltration in the control group, and less than a 1mm band of necrotic tissue in the test group. CONCLUSION: The Harmonic Focus Curved Shears, using Harmonic energy technology, appears to seal the pancreatic ducts and prevent pancreatic leak at 75% (3/4) efficiency in this survival model. However, the survival leak rate, 25% (1/4) was higher in the Harmonic Focus Curved Shears test group compared with the control oversewn group 0% (0/3). This feasibility study shows potential for Harmonic technology to be used to seal the pancreatic ducts, but additional testing and optimization of surgical techniques are needed.

Healing of reamed glenoid bone articulating with a metal humeral hemiarthroplasty: a canine model.

This study characterizes the healing response of the glenoid after spherical reaming and prosthetic humeral head replacement in a canine model of glenohumeral hemiarthroplasty. The right glenoid of twelve skeletally mature female dogs was reamed to a uniform radius of curvature, removing all cartilage down to bleeding subchondral bone. The glenoid was not resurfaced. The humeral head was replaced with a stemmed metal prosthesis. Post-surgery, the operated limbs were immobilized for seven days, with motion allowed ad libitum thereafter. Fluorescent bone labels were administered to identify bone formation. These procedures were not complicated by instability, infection or death. Six animals were euthanized at 10 week and six more at 24 week. The intact glenohumeral joints were evaluated by gross examination, assessment of glenoid concavity, and light microscopy of methylmethacrylate sections. At 10 week, vascular fibrous tissue partially covered the glenoid, maintaining a concave surface congruent with the prosthetic humeral head. New bone formed at the margin of the glenoid, and the density of the periarticular trabecular bone increased. At 24 week, the healing was more advanced; thick fibrocartilaginous tissue covered the entire glenoid surface. These results demonstrate that spherical glenoid reaming produced a consistent healing response characterized by remodelling of the reamed bony concavity to a congruent, living, smooth, securely attached interface articulating with the humeral prosthesis.

Influence of canine recombinant somatotropin hormone on biomechanical and biochemical properties of the medial meniscus in stifles with altered stability.

OBJECTIVE: To determine biomechanical and biochemical properties of the medial meniscus in a semi-stable stifle model and in clinical patients and to determine the effect of canine recombinant somatotropin hormone (STH) on those properties. ANIMALS: 22 healthy adult dogs and 12 dogs with meniscal damage secondary to cranial cruciate ligament (CCL) rupture. PROCEDURE: The CCL was transected in 15 dogs, and stifles were immediately stabilized. Implants releasing 4 mg of STH/d were placed in 7 dogs, and 8 received sham implants. Seven dogs were used as untreated controls. Force plate analysis was performed before surgery and 2, 5, and 10 weeks after surgery. After 10 weeks, dogs were euthanatized, and menisci from surgical and contralateral stifles were harvested. The torn caudal horn of the medial meniscus in dogs with CCL rupture comprised the clinical group. Creep indentation determined aggregate modulus (HA), Poisson's ratio (v), permeability (k), and percentage recovery (%R). Water content (%W), collagen content (C), sulfated glycosaminoglycan (sGAG) content, and collagen type-I (cI) and -II (cII) immunoreactivity were also determined. RESULTS: Surgical and clinical groups had lower HA, k, %R, C, sGAG, cI, and clI and higher %W than the non-surgical group. Surgical stifles with greater weight bearing had stiffer menisci than those bearing less weight. Collagen content was higher in the surgical group receiving STH than the surgical group without STH. CONCLUSIONS AND CLINICAL RELEVANCE: Acute stabilization and moderate weight bearing of the CCLdeficient stifle appear to protect stiffness of the medial meniscus. Normal appearing menisci from CCL-deficient stifles can have alterations in biomechanical and biochemical properties, which may contribute to meniscal failure.