Past, Present, and Future Trends of Nickel Titanium Rotary Instrumentation.

This article reviews the historical development, properties, and trends of nickel titanium rotary instrumentation use for the veterinary endodontist.

An easy to produce and economical three-dimensional brain phantom for stereotactic computed tomographic-guided brain biopsy training in the dog.

OBJECTIVE: To develop and validate a three-dimensional (3D) brain phantom that can be incorporated into existing stereotactic headframes to simulate stereotactic brain biopsy (SBB) and train veterinary surgeons. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Canine brain phantoms were fabricated from osteological skull specimens, agarose brain parenchyma, and cheddar and mozzarella cheese molds (simulating meningiomas and gliomas). METHODS: The neuroradiologic and viscoelastic properties of phantoms were quantified with computed tomography (CT) and oscillatory compression tests, respectively. Phantoms were validated by experienced and novice operators performing SBB on phantoms containing randomly placed, focal targets. Target yield and needle placement error (NPE) were compared between operators. RESULTS: Phantoms were produced in <4 hours, at an average cost of $92. The CT appearances of the phantom skull, agarose, and cheese components approximated the in vivo features of skull, brain parenchyma, and contrast-enhancing tumors of meningeal and glial origin, respectively. The complex moduli of the agarose and cheeses were comparable to the viscoelastic properties of in vivo brain tissues and brain tumors. The overall diagnostic yield of SBB was 88%. Although NPE did not differ between novice (median 3.68 mm; range, 1.46-14.54 mm) and experienced surgeons (median 1.17 mm, range, 0.78-1.58 mm), our results support the relevance of the learning curve associated with the SBB procedure. CONCLUSION: This 3D phantom replicates anatomical, CT, and tactile features of brain tissues and tumors and can be used to develop the technical skills required to perform SBB.

Revision of a BFX total hip replacement stem using a Kyon stem and a head adaptor in two dogs.

OBJECTIVE: To report revision of BFX cementless press-fit stem loosening with a Kyon cementless stem and a head adaptor in two dogs. METHODS: Total hip arthroplasty stem revision was performed in two dogs with loosening of a previously implanted Biomedtrix press-fit BFX stem. Both dogs had a well-integrated BFX cup and single stage revision was performed using a standard Kyon stem and a head adaptor in order to couple with a 17 mm head and maintain the BFX cup. RESULTS: Revisions resulted in a stable functional prosthesis with successful bone integration at the one-year postoperative re-evaluation. CONCLUSIONS: Use of a Kyon stem with a head adaptor may be a successful option to provide immediate stem stability for revision of a loosened BFX stem with a properly osseointegrated cup.

Advances in Laparoscopic Surgery.

Recently, a new platform of abdominal access, called single-port surgery, has emerged in human and veterinary laparoscopy. The single-port platform enables all laparoscopic instruments, including the telescope, to pass individually through the same abdominal incision. Recently, there have been several published reports documenting the efficacy and safety of single-port procedures in veterinary patients. This article discusses the common single-port devices and instrumentation, as well as procedures now routinely offered in veterinary minimally invasive surgery.

Advances in Flexible Endoscopy.

Flexible endoscopy, a minimally invasive diagnostic and potentially therapeutic tool, has become more available over the past decades. A fiberscope is used to visualize the lumen of the area of interest and collect tissue or fluid samples for evaluation. Samples can be submitted for histopathology, cytologic analysis, and bacterial culture. Flexible endoscopy is being investigated. This article provides a brief review of equipment and basic flexible endoscopy followed by an overview of advanced flexible endoscopic procedures that focuses on the gastrointestinal tract. The procedures included here may become more readily available and improve diagnosis and treatment.

Validation of an effective, easy-to-make hemostasis simulator.

The purpose of this study is to describe the construction method of a cost-effective, easy-to-make hemostasis simulator and to compare its effectiveness as a training tool to cadaver training. The simulator is made of materials commonly found in hospitals and clinics. These include a column manometer, a 500-ml saline bag, two intravenous fluid lines, a three-way stopcock, and a 6-mm-diameter Penrose drain. The device was tested on 10 final-year veterinary students. All participants tied 40 knots on the simulator and 40 knots on equine jejunal arteries sourced from a local abattoir. They were then asked to fill out a questionnaire comparing both methods. Participants assigned an overall assessment median score of 8.5/10 to the simulator and of 6.2/10 to cadaver practice. The simulator provided reliable haptic feedback, giving trainees a lifelike feel very close to that experienced when actually closing a blood vessel. In addition, it was effective in objectively evaluating students' ability to place ligatures on vessels. After adequate training, students' skills had significantly improved, alongside their confidence in placing hemostatic sutures. This proves our model is also useful in teaching basic open-surgery skills. Finally, its low production cost makes it ideally suited for self-practice.

In vivo biomechanical evaluation of a novel angle-stable interlocking nail design in a canine tibial fracture model.

OBJECTIVE: To compare clinical outcome and callus biomechanical properties of a novel angle stable interlocking nail (AS-ILN) and a 6 mm bolted standard ILN (ILN6b) in a canine tibial fracture model. STUDY DESIGN: Experimental in vivo study. ANIMALS: Purpose-bred hounds (n = 11). METHODS: A 5 mm mid-diaphyseal tibial ostectomy was stabilized with an AS-ILN (n = 6) or an ILN6b (n = 5). Orthopedic examinations and radiographs were performed every other week until clinical union (18 weeks). Paired tibiae were tested in torsion until failure. Callus torsional strength and toughness were statistically compared and failure mode described. Total and cortical callus volumes were computed and statistically compared from CT slices of the original ostectomy gap. Statistical significance was set at P < .05 RESULTS: From 4 to 8 weeks, lameness was less pronounced in AS-ILN than ILN6b dogs (P < .05). Clinical union was reached in all AS-ILN dogs by 10 weeks and in 3/5 ILN6b dogs at 18 weeks. Callus mechanical properties were significantly greater in AS-ILN than ILN6b specimens by 77% (failure torque) and 166% (toughness). Failure occurred by acute spiral (control and AS-ILN) or progressive transverse fractures (ILN6b). Cortical callus volume was 111% greater in AS-ILN than ILN6b specimens (P < .05). CONCLUSIONS: Earlier functional recovery, callus strength and remodeling suggest that the AS-ILN provides a postoperative biomechanical environment more conducive to bone healing than a comparable standard ILN.

Rapid prototyping to design a customized locking plate for pancarpal arthrodesis in a giant breed dog.

This report describes the treatment of traumatic carpal hyperextension in a giant breed dog by pancarpal arthrodesis using a custom-made Fixin locking plate, created with the aid of a three-dimensional plastic model of the bones of the antebrachium produced by rapid prototyping technology. A three-year-old 104 kg male Mastiff dog was admitted for treatment of carpal hyperextension injury. After diagnosis of carpal instability, surgery was recommended. Computed tomography images were used to create a life-size three-dimensional plastic model of the forelimb. The model was used as the basis for constructing a customized 12-hole Fixin locking plate. The plate was used to attain successful pancarpal arthrodesis in the animal. Radiographic examination after 74 and 140 days revealed signs of osseous union of the arthrodesis. Further clinical and radiographic follow-up examination three years later did not reveal any changes in implant position or complications.

Readability and histological biocompatibility of microchip transponders in horses.

Identification of horses by microchip transponder is mandatory within the European Union with only a few exceptions. In this study, the readability of such microchips in 428 horses with three different scanners (A, B and C) and the histological changes at the implantation site in 16 animals were assessed. Identification of microchips differed between scanners (P<0.001), and with 'side of neck' (P<0.001). Scanners A, B and C identified 93.5%, 89.7% and 100% of microchips, respectively, on the 'chip-bearing' side of the neck. From the contralateral side, scanners A, B and C identified 21.5%, 26.9% and 89.5% of transponders, respectively. Microchip readability was affected by age (P<0.001), but not by breed of horse. At necropsy, transponders were found in the subcutaneous fat (n=3), inter- or peri-muscular connective tissue (n=8), or musculature (n=5), where they were surrounded by a fibrous capsule ranging in thickness from 12.7 to 289.5 µm in 15 animals. In two animals, immature granulation tissue with attendant granulomatous inflammation, and a granulomatous myositis, surrounding the microchip were identified, respectively. Severe (n=1), moderate (n=1), and mild (n=3) lymphohistiocytic inflammation was noted within the fibrous capsule. Microchip transponders were found to be a highly reliable and biocompatible method of horse identification.

Ligation of the ovarian pedicles in dogs with a resorbable self-locking device--a long-term follow-up study.

A prospective clinical trial was performed to evaluate applicability, hemostatic efficiency, and long-term tissue reactions of a novel medical device. The device was made of polydioxanone and designed in principle as a cable-tie with a flexible band running through a locking case. It was tested for ligation of the ovarian pedicles during ovariohysterectomy in nine intact female dogs. The dogs were followed-up monthly by physical examination and ultrasonography of the abdomen for 5-12 months after surgery. Macroscopic and histological post mortem examinations were performed in two dogs 7 and 18 months after surgery. Hemostasis was achieved with the devices although 1 of the 18 devices needed further tightening during a reoperation. Ultrasonography revealed a hyperechoic device that caused acoustic shadowing, which decreased over time indicating gradual resorption. Post mortem examinations demonstrated adhesions and a local transient tissue reaction at site of the device. The results show that the device may be a future alternative for ligation of ovarian pedicles in dogs.

A novel intubation technique for minimally invasive longitudinal studies of rat lungs using hyperpolarized 3He magnetic resonance imaging.

Hyperpolarized noble gas (HNG) magnetic resonance imaging (MRI) has been shown to be useful for studying rodent models of lung disease. Image quality can be substantially degraded by signal loss from molecular oxygen entering the airway, requiring invasive surgery to ensure a good seal between the endotracheal (ET) tube and trachea. A modified Foley catheter having an inflatable cuff near the tip provides a novel approach for ensuring image quality for HNG MRI, thereby enabling longitudinal studies and reducing animal numbers. A Foley catheter was modified for rodent intubation and to minimize dead space. Three pairs of age-matched male Sprague Dawley rats 400 (30) g were used. Two pairs were intubated using the Foley and the third with an intravenous catheter. Leak rates were measured from pressure versus time curves within each animal. The pairs were euthanized immediately or six days postrecovery to assess the effects of the procedure on animal health, as reflected by histological examination. The Foley catheter resulted in minimal leak rates (-0.20 (0.03) versus -0.16 (0.05) cmH(2)O/s), and were shown to be well below upper-limit leak rates of -0.5 and -0.7 cmH(2)O/s. Tracheal samples from rats in a separate Foley group (not mechanically ventilated) showed superficial damage six days postextubation (grade = 0). (3)He imaging performed using the Foley showed good image quality. Though some technical issues remain to be solved, a modified Foley catheter used as an ET tube offers the potential to enable longitudinal studies in rodents and reduce animal numbers.

Vascular access port implantation and serial blood sampling in a Gottingen minipig (Sus scrofa domestica) model of acute radiation injury.

Threats of nuclear and other radiologic exposures have been increasing, but no countermeasure for acute radiation syndrome has been approved by regulatory authorities. Because of their similarity to humans in regard to physiology and anatomy, we are characterizing Gottingen minipigs as a model to aid the development of radiation countermeasures. Irradiated minipigs exhibit immunosuppression, severe thrombocytopenia, vascular leakage, and acute inflammation. These complications render serial acquisition of blood samples problematic. Vascular access ports (VAP) facilitate serial sampling, but their use often is complicated by infections and fibrin deposition. We demonstrate here the successful use of VAP for multiple blood samplings in irradiated minipigs. Device design and limited postoperative prophylactic antimicrobial therapy before irradiation were key to obtaining serial sampling, reducing swelling, and eliminating infection and skin necrosis at the implantation site. Modifications of previous protocols included the use of polydioxanone sutures instead of silk; eliminating chronic port access; single-use, sterile, antireflux prefilled syringes for flushing; strict aseptic weekly maintenance of the device, and acclimating animals to reduce stress. VAP remained functional in 19 of 20 irradiated animals for as long as 3 mo. The remaining VAP failed due to a small leak in the catheter, leading to clot formation. VAP-related sepsis occurred in 2 minipigs. Blood sampling did not cause detectable stress in nonanesthetized sham-irradiated animals, according to leukograms and clinical signs.

Design and evaluation of a low-cost respiratory monitoring device for use with anaesthetized animals.

This report describes a simple, non-invasive electronic device that employs a compact accelerometer integrated circuit to transduce movements in the chest wall of an anaesthetized animal into an analogue signal that can be used to calculate the rate and relative depth of respiration. The device requires amplification by signal processing hardware/software which are common to most experimental laboratories. We assessed the sensitivity of the device by its ability to detect changes in respiratory patterns produced by modulating the depth of anaesthesia in isoflurane-anaesthetized Wistar rats. It is widely accepted that many anaesthetic agents affect respiratory patterns, especially respiratory rate (RR), which is often used as an important index of anaesthetic depth. Respiratory parameters obtained with the device were compared with concurrently recorded electroencephalographic and cardiac measures. Different concentrations of anaesthetic agent produced four depths of anaesthesia, identified using established electroencephalographic criteria. The accelerometer was attached easily and securely to the location of maximal chest wall movement and produced a strong respiratory signal that was detectable in all four anaesthetic stages. Deepening the anaesthesia produced a gradual decrease in RR, a decrease in dominant spectral frequency of the electroencephalogram (EEG) but no change in the heart rate. There was a significant correlation between RR and the dominant spectral frequency of the EEG, indicating that one useful application of the monitor could be to identify anaesthetic stages. The results demonstrate that respiratory parameters can be recorded using a simply constructed, low-cost device and suggest an application in the monitoring of anaesthetic depth.

External fixator clamp reuse degrades clamp mechanical performance.

OBJECTIVE: To determine the effects of clamp reuse for the Kirschner-Ehmer (KE); Securos; and the IMEX-SK clamp. STUDY DESIGN: Experimental bench test of mechanical properties. METHODS: Specially designed fixtures were used to mechanically test 18 clamps of each type with respect to 6 mechanical variables: fixator pin slippage, connecting bar slippage, fixator pin rotation, connecting bar rotation, and clockwise and counterclockwise clamp-bolt axis pivot. Each clamp was tested 6 times for each variable at 7.68 Nm of clamp-bolt tightening torque. RESULTS: were compared using repeated measures ANOVA. Results- For the IMEX-SK clamp, a significant degradation in the force required to cause slippage was found for connecting bar slippage and fixator pin rotation; however, this clamp also had a significant increase in the force to initiate slippage for clockwise clamp-bolt axis pivot with reuse. The Securos clamp had significant degradation in connecting bar slippage, connecting bar rotation, and fixator pin rotation whereas the KE clamp had significant degradation in connecting bar slippage only. CONCLUSIONS: All 3 external fixator clamp types degraded in 1 or more movement variables in their ability to resist motion with reuse. The IMEX and Securos clamps were more subject to degradation than the KE clamp and this may have clinical importance for fixator composite rigidity. CLINICAL RELEVANCE: Fracture-reduction stability is related to the ability to resist motion within a clamp. The unpredictable nature of degradation we found cautions against repeated use. Clinicians should consider reuse of external fixator clamps with the knowledge that repeated use degrades clamp mechanical performance.

Comparison of alternate and simultaneous tensioning of wires in a single-ring fixator construct.

OBJECTIVE: To measure and compare the strain of wires tensioned with alternate (ALT) and simultaneous (SIM) tensioning in a single-ring fixator construct and compare the stiffness of these constructs under axial loading. STUDY DESIGN: Experimental mechanical study. SAMPLE POPULATION: Twenty-four, 84 mm diameter, single-ring constructs. METHODS: Twenty-four, 84 mm diameter, single-ring constructs were assembled using 2 1.6 mm wires placed at a 60 degrees angle tensioned with either ALT or SIM technique to 90 kg tension. Voltage data from a strain gauge were recorded during the wire-tensioning process, cyclic axial loading, and load-to-failure testing. Wire strains were calculated for each wire and compared within constructs and between ALT and SIM groups. Construct stiffness was compared between groups. RESULTS: There was no difference between the tensioning methods in final wire strains after initial tensioning for both the wire below the ring (W1; P=.698) and the wire above the ring (W2; P=.233). There was also no difference in final wire strains within each tensioning method group (ALT, P=.289; SIM, P=.583). Loss of wire strain (3.5-5%) occurred after cyclic loading for both wires in both groups. There was no difference in construct stiffness between the ALT and SIM groups (P=.126). Mode of failure was by wire breakage in all constructs and occurred most frequently in W1. CONCLUSION: ALT tensioning of wires produced similar wire strains within a single-ring construct after initial tensioning to SIM tensioned wires. There was no difference in construct stiffness under axial loading between AIM and SIM tensioned constructs. CLINICAL RELEVANCE: ALT tensioning of wires in a single-ring fixator construct can be used as an alternative to SIM tensioning, as similar initial wire tensions are achieved.

Nonlinear stiffness profiles of external fixators constructed with composite rods.

OBJECTIVE: To determine if composite connecting rods confer nonlinear stiffness characteristics on unilateral and bilateral external skeletal fixators (ESF) in cranial-caudal bending and axial loading. STUDY DESIGN: Mechanical testing performed on models. SAMPLE POPULATION: Six models of 6-pin ESF constructs composed of birch dowels, a commercial ESF system, and composite connecting rods. METHODS: Unilateral and bilateral ESF configurations were assembled using either specially designed composite titanium and silicone (composite group) or solid titanium (solid group) connecting rods. Mechanical testing was performed in axial loading and 4-point cranial-caudal bending. Stiffness was determined at a low and high-load range, and was considered increasing and nonlinear if the stiffness at high loads was greater than at low loads. RESULTS: The stiffness of the solid group was linear in all testing modes and configurations. Bilateral composite fixators had a nonlinear increasing stiffness in axial loading and cranial-caudal bending. Unilateral composite fixators had a nonlinear increasing stiffness in axial loading, but not cranial-caudal bending. Solid connecting rods conferred a higher stiffness in all testing modes and configurations. CONCLUSIONS: Composite connecting rods resulted in nonlinear increasing axial and bending stiffness in bilateral fixators, and in axial load in unilateral fixators. CLINICAL RELEVANCE: Conventional ESF can be constructed so that the stiffness increases as load increases. This provides the surgeon with additional options to control the local mechanical environment of a healing fracture, which may be used to enhance fracture healing.

Ex vivo comparison of one versus two distal screws in 8 mm model 11 interlocking nails used to stabilize canine distal femoral fractures.

OBJECTIVE: To compare the structural properties of an 8 mm model 11 interlocking nail (IN) with 2 proximal and 2 distal screws (2/2) to 2 proximal and 1 distal screws (2/1) in an unstable canine fracture model. STUDY DESIGN: Ex vivo biomechanical investigation. SAMPLE POPULATION: Eight pairs of adult canine femurs. METHODS: A simple transverse distal metaphyseal femoral fracture with a 1 cm gap was created. The unstable fracture in 1 femur was repaired with a nail with 2 distal and 2 proximal screws and the paired femur with a nail with 1 distal and 2 proximal screws. Cyclic mechanical testing in torsion was performed to assess fatigue life, peak torque, stiffness, and mode of failure. RESULTS: All 2/1 IN-femoral constructs, but only 2 of eight 2/2 constructs, failed before completion of 50,000 loading cycles. The 2/2 constructs had significantly greater peak torque to failure (P = .002) and longer fatigue life (P = .00003) compared with 2/1 constructs. There were no significant differences in stiffness between 2/2 and 2/1 constructs when the non-failed constructs were compared (P > .5). All constructs failed by screw deformation. CONCLUSIONS: An 8 mm model 11 IN used for fixation of unstable canine distal femoral fractures has a longer fatigue life and is stronger under torsional loads when 2 rather than 1 distal screws are placed. CLINICAL RELEVANCE: When repairing unstable canine distal femoral fractures with an IN system, 2 distal screws should be inserted to avoid catastrophic implant failure before bone healing is achieved.

Biomechanical Analysis of Unilateral External Skeletal Fixators Combined with IM-Pin and Without IM-Pin Using Finite-Element Method.

OBJECTIVES: To determine if a unilateral external skeletal fixator (ESF) with a carbon fiber connecting rod (IMEX SK) without an intramedullary (IM)-pin is mechanically comparable with a unilateral ESF with a stainless-steel connecting rod (IMEX KE) with an IM-pin. STUDY DESIGN: Finite-element method (FEM)-computer simulation. METHODS: FEM models were validated by comparison against data from mechanical testing. Three-dimensional FEM models of a femur with a mid-diaphyseal fracture with a 20 mm gap were developed with 4 unilateral external skeletal fixator devices (6-pin KE, 6-pin KE IM-pin, 6-pin SK, and 6-pin SK IM-pin). A 300 N load was applied to the femur at the proximal end in a direction of theta = 10 degrees distally and phi = 10 degrees laterally cranially. Relative displacements in x-, y- and z-directions at the gap were obtained and the overall stiffness was calculated as 300 N/total displacement. Load transfer at the pin-bone interface (PBI) was assessed by determining the von Mises stress maxima at the PBI-related nodes. RESULTS: The 6-pin SK had superior mechanical performance compared with the 6-pin KE by exhibiting smaller displacements in all directions and higher stiffness. Compared with the 6-pin KE IM-pin, the 6-pin SK (without IM-pin) was superior in craniocaudal and lateromedial displacements, but inferior in axial displacements, overall stiffness and von Mises stress maxima. The 6-pin SK IM-pin was superior to the 6-pin KE IM-pin based on smaller displacements and higher stiffness. CONCLUSIONS: Although the SK device had superior mechanical performance compared with a KE device in a unilateral configuration, the addition of an IM-pin continues to be a powerful method of enhancing mechanical performance of either IMEX SK or IMEX KE unilateral constructs in clinical cases. CLINICAL RELEVANCE: Based on the results of this FEM study we recommend the use of the "tied-in" IM-pin with the ESF clinically when striving for high rigidity. In less challenging situations, a unilateral SK ESF without IM-pin might provide sufficient rigidity for a successful fracture repair.

Comparison of 23 gauge and 25 gauge anterior capsulotomy forceps.

In cataract surgery, the most commonly-used procedure for incision of the anterior capsule is continuous curvilinear capsulorrhexis (CCC), developed by Gimbel and Neuhann. As Gimbel has reported, CCC is a safe technique for phacoemulsification and aspiration (PEA) and intraocular lens (IOL) implantation. The optimum incision method for CCC is thought to be that of using anterior capsulotomy forceps. Recently, I have developed the side-port 23 gauge anterior capsulotomy forceps (23G forceps), manufactured by Asico, which can be manipulated via a small incision, as well as the side-port 25 gauge anterior capsulotomy forceps (25G forceps) and 25/23 gauge tapered anterior capsulotomy forceps (tapered forceps), manufactured by Inami, which are thought to provide even better ease of handling. In view of the fact that the visibility, ease of handling, bending, adverse effect on the wound, and effect on the cornea of these various forceps are important, the present comparison study among these forceps was conducted on pig lenses by means of 0.1 % trypan blue staining of the anterior capsule. It was found that capsulorrhexis was difficult with the 25G forceps because of the strong bend of the shaft. However, the tapered forceps has little bend, and like the 23G forceps, it showed outstanding handling and visibility and had little adverse effect on the wound.

Mechanical comparison of 3 different clamp and 2 different rod types of a new veterinary internal fixation system, 4.5/5.5-mm VetFix.

OBJECTIVE: To compare the gripping force of a standard clamp with click-on and T clamps of the 4.5/5.5-mm VetFix (AO Research Institute, Davos, Switzerland), mounted on smooth and roughened rods. STUDY DESIGN: In vitro mechanical study. METHODS: Rods were mounted on a clamp-holding device. Each clamp type was tested on a materials-testing machine in groups of 6 specimens for torsional and axial load stability on smooth and roughened rods (total, 72 specimens). The variable evaluated was the discontinuity point (DP) as a measure for gliding resistance of the clamp on the rod. Means (+/-SD) were calculated for all groups separately. For statistical comparison, a multiple regression model was fitted with level of significance set at P =.05. RESULTS: The direction of torsion had a significant effect on DP for both asymmetric clamps (standard, click-on). In torsion and axial load, the roughened rod had significantly higher DP levels than the smooth rod for the standard clamp. Rods differed only in axial load for the T clamp, again favoring the roughened rod. The click-on clamp did not reach 10% of the values achieved by the other clamps, independent from the rods and loading conditions. Compared with the T clamp, standard clamp DP values were significantly higher in torsion on the roughened rod as well as in axial load on both rod types. CONCLUSIONS: The roughened rod with a standard clamp was mechanically superior. For the T clamp, the small loss of gripping force may be compensated for by the possibility of inserting 2 more screws. CLINICAL RELEVANCE: The roughened rod may enhance the bending, compressive, and torsional properties of the 4.5/5.5-mm VetFix system by reducing the risk of clamp gliding on the rod. The standard clamp is the clamp of choice, except for the metaphyseal or epiphyseal region, at which use of a T clamp may be indicated to increase the number of screws inserted at the end of the rod.