Biomechanical evaluation of interlocking nail and locking compression plating for stabilization of ovine critical-sized segmental tibia defects.

Background: Segmental large volume bone loss resulting from fracture or osseous neoplasia is a major challenge to orthopedic surgeons and there is an ongoing quest to identify treatments that optimize healing. To advance treatment, large animal translational models-such as the ovine critical-sized tibia defect model-are instrumental for testing of novel scaffolds for bone regeneration. However, little standardization in the implants utilized for defect stabilization has been determined and current commercially available implants may be inadequate to replicate the strength of the native tibia.

Enhanced bone formation in locally-optimised, low-stiffness additive manufactured titanium implants: An in silico and in vivo tibial advancement study.

A tibial tuberosity advancement (TTA), used to treat lameness in the canine stifle, provides a framework to investigate implant performance within an uneven loading environment due to the dominating patellar tendon. The purpose of this study was to reassess how we design orthopaedic implants in a load-bearing model to investigate potential for improved osseointegration capacity of fully-scaffolded mechanically-matched additive manufactured (AM) implants. While the mechanobiological nature of bone is well known, we have identified a lower limit in the literature where investigation into exceedingly soft scaffolds relative to trabecular bone ceases due to the trade-off in mechanical strength.

The Effect of Anterior Cruciate Ligament Reconstruction with an Electropsun Scaffold on Tibiofemoral Contact Mechanics.

Surgical reconstruction of the torn ACL is performed to restore native contact mechanics. Drawbacks to traditional ACL repair techniques motivate the development of a tissue engineered ACL scaffold. Our group has developed a hierarchical electrospun polycaprolactone (PCL) scaffold that consists of rolled nanofiber bundles attached at each end with solvent-case blocks of PCL.

Ventral femoral head and neck ostectomy: Standard versus novel K-wire guided technique using a premeasured ostectomy angle in canine cadavers.

Objective: To assess the accuracy and efficiency of performing ventral FHO (vFHO) after measuring the ideal femoral head and neck ostectomy angle (iFHOA), with and without guidance of a K-wire. To compare the iFHOA to the previously accepted 45° angle to guide vFHOs.

Study Design: Randomized, controlled, ex vivo study.

Investigation of a Prevascularized Bone Graft for Large Defects in the Ovine Tibia.

bioreactors are a promising approach for engineering vascularized autologous bone grafts to repair large bone defects. In this pilot parametric study, we first developed a three-dimensional (3D) printed scaffold uniquely designed to accommodate inclusion of a vascular bundle and facilitate growth factor delivery for accelerated vascular invasion and ectopic bone formation. Second, we established a new sheep deep circumflex iliac artery (DCIA) model as an bioreactor for engineering a vascularized bone graft and evaluated the effect of implantation duration on ectopic bone formation.

Osteoinductive 3D printed scaffold healed 5 cm segmental bone defects in the ovine metatarsus.

Autologous bone grafts are considered the gold standard grafting material for the treatment of nonunion, but in very large bone defects, traditional autograft alone is insufficient to induce repair. Recombinant human bone morphogenetic protein 2 (rhBMP-2) can stimulate bone regeneration and enhance the healing efficacy of bone grafts. The delivery of rhBMP-2 may even enable engineered synthetic scaffolds to be used in place of autologous bone grafts for the treatment of critical size defects, eliminating risks associated with autologous tissue harvest.

An assessment of mechanical properties and screw push-out for two 3.5-mm pearl-type locking plate systems.

Objective: To compare mechanical properties (stiffness, yield load, failure load, and deformation at failure) of 2 pearl-type locking plate system (PLS) constructs (PLS 1 and PLS 2) in a simulated fracture gap model and to compare screw push-out forces of the 2 PLSs with and without plate contouring.

Sample: 40 PLS constructs.

Procedures: Mechanical properties of uncontoured PLS 1 (n = 8) and PLS 2 (8) constructs were evaluated in synthetic bone-plate models under axial compression.

Gait and electromyographic alterations due to early onset of injury and eventual rupture of the cranial cruciate ligament in dogs: A pilot study.

Objective: Identify relevant electromyography (EMG), kinematic, and kinetic changes resulting from monopolar radiofrequency energy (MRFE)-induced cranial cruciate ligament (CCL) injury and eventual rupture in dogs.

Study Design: Experimental, repeated measures.

Animals: Five purpose-bred female dogs free of orthopedic and neurologic disease.

Postamputation Orthopedic Surgery in Canine Amputees: Owner Satisfaction and Outcome.

Surgical management of postamputation orthopedic disease (PAOD) in canine amputees has rarely been documented, and no reports describing outcome of stifle surgery in canine amputees are available. The objective of this multisite retrospective case series was to describe cases and evaluate satisfaction with and outcome of postamputation orthopedic surgery in canine amputees. Data was obtained through medical records and owner survey responses; data included signalment, amputation cause, diagnosis, surgical treatment, timeframes, and outcome assessment.

An investigation of shock wave therapy and low-intensity pulsed ultrasound on fracture healing under reduced loading conditions in an ovine model.

The use of shock wave therapy (SWT) and low-intensity pulsed ultrasound (LIPUS) as countermeasures to the inhibited fracture healing experienced during mechanical unloading was investigated by administering treatment to the fracture sites of mature, female, Rambouillet Columbian ewes exposed to partial mechanical unloading or full gravitational loading. The amount of fracture healing experienced by the treatment groups was compared to controls in which identical surgical and testing protocols were administered except for SWT or LIPUS treatment. All groups were euthanized after a 28-day healing period.

The effect of polydioxanone hemicerclage suture on the occurrence of fracture during tibial tuberosity advancement with an elongated bi-directional hinged osteotomy.

Objective: To investigate the effect of hemicerclage suture on the occurrence of fractures during advancement of an elongated bi-directional hinged osteotomy (EBHO) for tibial tuberosity advancement (TTA) in dogs.

Study Design: Experimental ex vivo study.

Animals: Canine cadavers (n = 14) METHODS: A uniform EBHO was performed in 28 cadaveric hind limbs (n = 28) from 14 skeletally mature, medium-sized, mixed breed dogs.

Comparison of owner satisfaction between stifle joint orthoses and tibial plateau leveling osteotomy for the management of cranial cruciate ligament disease in dogs.

OBJECTIVE To compare owner satisfaction between custom-made stifle joint orthoses and tibial plateau leveling osteotomy (TPLO) for the management of medium- and large-breed dogs with cranial cruciate ligament disease (CCLD). DESIGN Owner survey. SAMPLE 819 and 203 owners of dogs with CCLD that were managed with a custom-made stifle joint orthosis or TPLO, respectively.

Hemiepiphysiodesis for the correction of proximal tibial valgus in growing dogs.

Objectives: To describe the use of hemiepiphysiodesis for the treatment of proximal tibial deformities in immature dogs and evaluate the effect on the mechanical medial proximal tibial angle (mMPTA).

Methods: Skeletally immature dogs with proximal tibial deformities from three institutions treated with hemiepiphysiodesis between March 2006 and January 2015 were included. All dogs were required to have an mMPTA outside the previously published reference range (93.

Computational characterization of fracture healing under reduced gravity loading conditions.

The literature is deficient with regard to how the localized mechanical environment of skeletal tissue is altered during reduced gravitational loading and how these alterations affect fracture healing. Thus, a finite element model of the ovine hindlimb was created to characterize the local mechanical environment responsible for the inhibited fracture healing observed under experimental simulated hypogravity conditions. Following convergence and verification studies, hydrostatic pressure and strain within a diaphyseal fracture of the metatarsus were evaluated for models under both 1 and 0.

Microsphere-based gradient implants for osteochondral regeneration: a long-term study in sheep.

Background: The microfracture technique for cartilage repair has limited ability to regenerate hyaline cartilage.

Aim: The current study made a direct comparison between microfracture and an osteochondral approach with microsphere-based gradient plugs.

Materials & Methods: The PLGA-based scaffolds had opposing gradients of chondroitin sulfate and β-tricalcium phosphate.

Implantable microelectromechanical sensors for diagnostic monitoring and post-surgical prediction of bone fracture healing.

The relationship between modern clinical diagnostic data, such as from radiographs or computed tomography, and the temporal biomechanical integrity of bone fracture healing has not been well-established. A diagnostic tool that could quantitatively describe the biomechanical stability of the fracture site in order to predict the course of healing would represent a paradigm shift in the way fracture healing is evaluated. This paper describes the development and evaluation of a wireless, biocompatible, implantable, microelectromechanical system (bioMEMS) sensor, and its implementation in a large animal (ovine) model, that utilized both normal and delayed healing variants.

Piezoelectric surgery -a novel technique for laminectomy.

Objective: Piezoelectric surgery is a novel technology that allows for the osteotomy of mineralized tissue with less risk of damaging underlying soft tissue structures. This selective cutting increases the safety of osteotomies performed in close vicinity to delicate structures such as dura mater, blood vessels, and neural tissue. This study aimed to develop and describe the technique of piezoelectric surgery for dorsal laminectomy and to assess its clinical safety in normal sheep.

Partial gravity unloading inhibits bone healing responses in a large animal model.

The reduction in mechanical loading associated with space travel results in dramatic decreases in the bone mineral density (BMD) and mechanical strength of skeletal tissue resulting in increased fracture risk during spaceflight missions. Previous rodent studies have highlighted distinct bone healing differences in animals in gravitational environments versus those during spaceflight. While these data have demonstrated that microgravity has deleterious effects on fracture healing, the direct translation of these results to human skeletal repair remains problematic due to substantial differences between rodent and human bone.

In vitro incidence of fibular penetration with and without the use of a jig during tibial plateau leveling osteotomy.

Objective: To determine the incidence of fibular penetration during placement of the Synthes® locking TPLO plate with and without the use of a jig.

Study Design: Cadaveric, experimental study.

Sample Population: Cadaveric paired pelvic limbs (n = 8) from skeletally mature dogs.

Arthroscopic biceps ulnar release procedure (BURP): technique description and in vitro assessment of the association of visual control and surgeon experience to regional damage and tenotomy completeness.

Objectives: (1) Describe arthroscopic BURP surgical technique, (2) assess association of visual control and surgeon experience to tenotomy completeness and regional iatrogenic tissue damage.

Study Design: Cadaveric study.

Sample Population: Canine cadavers weighing >20 kg (n = 16; 32 elbows).

The effect of preoperative planning method on recommended tibial tuberosity advancement cage size.

Objective: To determine if use of various commonly practiced tibial tuberosity advancement (TTA) preoperative planning methods leads to variable TTA cage size recommendations.

Study Design: Radiographic study.

Animals: Dogs (n = 14) with naturally occurring cranial cruciate ligament disease.

An in vivo ovine model of bone tissue alterations in simulated microgravity conditions.

Microgravity and its inherent reduction in body-weight associated mechanical loading encountered during spaceflight have been shown to produce deleterious effects on important human physiological processes. Rodent hindlimb unloading is the most widely-used ground-based microgravity model. Unfortunately, results from these studies are difficult to translate to the human condition due to major anatomic and physiologic differences between the two species such as bone microarchitecture and healing rates.

The role of muscle activation in cruciate disease.

Traditional investigations into the etiopathogenesis of canine cranial cruciate ligament (CCL) disease have focused primarily on the biological and mechanical insults to the CCL as a passive stabilizing structure of the stifle. However, with recent collaboration between veterinarians and physical therapists, an increased focus on the role of muscle activity and aberrant motor control mechanisms associated with anterior cruciate ligament (ACL) injuries and rehabilitation in people has been transferred and applied to dogs with CCL disease. Motor control mechanisms in both intact and cruciate-deficient human knees may have direct translation to canine patients, because the sensory and motor components are similar, despite moderate anatomic and biomechanical differences.

Prevalence of dysphoria after fentanyl in dogs undergoing stifle surgery.

Objective: To describe the prevalence of dysphoria after intraoperative administration of fentanyl by infusion and identify other risk factors influencing this in dogs undergoing stifle surgery.

Study Design: Prospective, randomized clinical study.

Animals: Dogs (n = 92) that had tibial plateau leveling osteotomy (TPLO) or tibial tuberosity advancement (TTA).

External fixators and minimally invasive osteosynthesis in small animal veterinary medicine.

Modern external skeletal fixation (ESF) is a very versatile system that is well suited to the ideals of minimally invasive osteosynthesis (MIO). It offers variable-angle, locked fixation that can be applied with minimal to no disruption of the fracture zone. Technological advances in ESF have fostered the ability to use more simple frame applications than in previous generations.