Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model.

Background: Advances in immunomagnetic cell sorting have enabled isolation and purification of pleuripotent stem cells from marrow aspirates and have expanded stem cell therapies to include allogeneic sources.

Purpose: This study aimed to determine the safety and efficacy of allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold in lumbar interbody spinal fusion using an ovine model.

Study Design: Thirty-two skeletally mature ewes underwent a single-level interbody fusion procedure using a Polyetheretherketone fusion cage supplemented with either iliac crest autograft (AG) or an osteconductive scaffold (Mastergraft Matrix, Medtronic, Memphis, TN, USA) with 2.

Allogeneic mesenchymal progenitor cells for posterolateral lumbar spine fusion in sheep.

Background Context: Osteoconductive porous ceramic bone graft materials supplemented with mesenchymal precursor cells (MPC) derived from autologous bone marrow aspirates have been shown to stimulate successful interbody and posterolateral spine fusion in preclinical models. Recent advances in immunomagnetic cell sorting have enabled purification and isolation of pluripotent stem cells from marrow aspirates and have expanded stem cell technology to allogeneic cell sources. Allogeneic MPC technology combined with appropriate synthetic biomaterial carriers could provide both the osteogenic and osteoconductive components needed for successful posterolateral spine fusion without the need for autologous bone harvest or expensive recombinant protein technology.

Regeneration of periodontal tissues using allogeneic periodontal ligament stem cells in an ovine model.

Aim: To investigate the capacity of allogeneic periodontal ligament stem cells (PDLSCs) to regenerate periodontal tissues using an ovine periodontal defect model.

Materials & Methods: Surgically created zero-wall dehiscence periodontal defects created in Merino sheep were filled with 1 × 10(7) allogeneic PDLSCs attached to Gelfoam(®), Gelfoam alone or left untreated. After 4 weeks, histological analysis was performed to assess periodontal regeneration.

Effects of (60)Co gamma radiation dose on initial structural biomechanical properties of ovine bone--patellar tendon--bone allografts.

Gamma radiation is established as a procedure for inactivating bacteria, fungal spores and viruses. Sterilization of soft tissue allografts with high dose (60)Co gamma radiation has been shown to have adverse effects on allograft biomechanical properties. In the current study, bone-patellar tendon-bone (BPTB) allografts from 32 mature sheep were divided into two treatment groups: low-dose radiation at 15 kGy (n = 16) and high-dose radiation at 25 kGy (n = 16) with the contralateral limb serving as a 0 kGy (n = 32) non-irradiated control.

Gene therapy to enhance allograft incorporation after host tissue irradiation.

Structural bone allografts are used to reconstruct large skeletal defects after tumor surgery. Although allograft-related complications are declining, the use of perioperative radiation therapy is associated with a poorer outcome. Recently, BMP-2 levels in the host bed were reportedly diminished after exposure to radiation doses consistent with those used perioperatively to treat musculoskeletal sarcoma.

Effects of low intensity pulsed ultrasound with and without increased cortical porosity on structural bone allograft incorporation.

Background: Though used for over a century, structural bone allografts suffer from a high rate of mechanical failure due to limited graft revitalization even after extended periods in vivo. Novel strategies that aim to improve graft incorporation are lacking but necessary to improve the long-term clinical outcome of patients receiving bone allografts. The current study evaluated the effect of low-intensity pulsed ultrasound (LIPUS), a potent exogenous biophysical stimulus used clinically to accelerate the course of fresh fracture healing, and longitudinal allograft perforations (LAP) as non-invasive therapies to improve revitalization of intercalary allografts in a sheep model.

Hollow calcium phosphate microcarriers for bone regeneration: in vitro osteoproduction and ex vivo mechanical assessment.

Synthetic grafting materials, such as calcium phosphates (hydroxyapatite, HA; tricalcium phosphate, TCP), polymers, or composites thereof, can be used as osteoconductive scaffolds and delivery vehicles for osteoinductive growth factors. Carrier materials must be engineered to deliver these factors in a controlled fashion at a rate and dose consistent with the biological need and responsiveness of the system to optimize bone formation and ingrowth. They should also simultaneously provide mechanical support and slowly resorb as new bone is formed.

A mechanical and computational investigation on the effects of conduit orientation on the strength of massive bone allografts.

Structural bone allografts are used to reconstruct large skeletal defects resulting from trauma, tumor resection, or revision arthroplasty. Though used for over a century, bone allografts suffer from a high rate of mechanical failure due to limited graft revitalization even after extended periods in vivo. The current study evaluated the mechanical properties of longitudinally perforated cortical bone allografts (LAP) that have been shown to promote accelerated graft incorporation in a large animal model.

Efficacy of silicated calcium phosphate graft in posterolateral lumbar fusion in sheep.

Background Context: Conditions requiring posterior lumbar spinal fusion remain a clinical challenge. Achieving arthrodesis using autogenous bone graft is inconsistent when rigid internal fixation such as transpedicular instrumentation is applied. Synthetic materials, particularly calcium phosphate-based ceramics, have shown promise for spine fusion applications, especially when combined with autograft.

In vivo BMP-7 (OP-1) enhancement of osteoporotic vertebral bodies in an ovine model.

Background Context: Prevention of osteoporotic vertebral fractures could help at-risk individuals avoid the pain and morbidity associated with these fractures. Currently, patients with osteoporosis are treated with systemic medications to reduce fracture risk. Although effective, these therapies do not eliminate fractures and also tend to have a gradual time-dependent effect on fracture risk.

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.

Cortical bone graft and endoprosthesis in the distal radius of dogs: a biomechanical comparison of two different limb-sparing techniques.

Objective: To compare the biomechanical properties of cortical bone and surgical steel endoprosthesis for limb-sparing surgery of the distal radius in dogs and evaluate the role of the ulna in providing stability to the reconstructed limb.

Study Design: Cadaveric biomechanical study.

Animals: Twelve pairs of normal canine thoracic limbs.

Evaluation of subchondral bone mineral density associated with articular cartilage structure and integrity in healthy equine joints with different functional demands.

Objective: To determine and correlate subchondral bone mineral density and overlying cartilage structure and tensile integrity in mature healthy equine stifle (low magnitude loading) and metacarpophalangeal (high magnitude loading) joints.

Animals: 8 healthy horses, 2 to 3 years of age.

Procedure: Osteochondral samples were acquired from the medial femoral condyle (FC) and medial trochlear ridge (TR) of the stifle joint and from the dorsal (MC3D) and palmar (MC3P) aspects of the distal medial third metacarpal condyles of the metacarpophalangeal joint.

Radial nerve excursion and strain at the elbow and wrist associated with upper-extremity motion.

Purpose: This study evaluated the excursion necessary to accommodate common motions of daily living and associated strain on the radial nerve. The radial nerve was evaluated at the wrist and proximal to the elbow before it bifurcated.

Methods: Five fresh-frozen transthoracic cadaver specimens (10 arms) were dissected; the radial nerve was exposed at the elbow and wrist only enough to be marked with a microsuture.

Allograft bone decreases in strength in vivo over time.

Allograft bone is the primary source of graft material for structural oncological limb salvage procedures. Failure rates after massive allograft reconstructions have been reported as high as 60% at 10 years, which are associated with a multitude of biologic processes influencing the graft incorporation and functional capacity. It is unknown if mechanical failure is associated with a gradual loss of bulk material properties of the bone (strength and modulus), loss of bone mineral density, osteoclastic resorption of the allograft, unrepaired allograft microfractures or microcracks, and/or local stress concentration within the tissue.

Grafting of massive tibial subchondral bone defects in a caprine model using beta-tricalcium phosphate versus autograft.

Objective: This study evaluated the ability of beta-tricalcium phosphate particles (beta-TCP) and autograft (AUTO) to maintain joint surface morphology when used to supplement massive subchondral bone defects in a caprine model.

Design: This was a prospective, parallel arm study with 2 experimental arms and a control group.

Methods: Unilateral, 11 mm diameter, 25 mm deep cylindrical defects were created in tibial subchondral bone of anesthetized goats (n = 16) and filled with autograft or beta-tricalcium phosphate particles.

An assessment of equine cartilage degeneration.

Millions of Americans suffer from osteoarthritis, a joint disease characterized by cartilage degradation and subchondral bone sclerosis. However, little is known about its pathology. It remains to be discovered which comes first in the progression of osteoarthritis: subchondral bone remodeling or cartilage degeneration.

Efficacy of osteogenic protein-1 in a challenging multilevel fusion model.

Study Design: A therapeutic study compared the influence of osteogenic protein-1 to autograft and collagen carrier in multilevel sheep spine fusions.

Objective: To evaluate the efficacy of osteogenic protein-1 compared to autograft and collagen carrier in achieving fusion in a challenging multilevel lumbar spine ovine model.

Summary Of Background Data: Bone morphogenetic proteins can successfully augment spinal fusion.

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

Object: Iliac crest bone graft harvesting can result in major complications, the rates of which range from approximately 6 to 8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft.

Methods: In skeletally mature sheep, a tricortical iliac crest graft was harvested.

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

Iliac crest bone graft harvesting can result in major complications that occur at rates of approximately 6%-8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft. In skeletally mature sheep, a tricortical iliac crest graft was harvested.

Radiographic and histologic analysis of the tibial tunnel after allograft anterior cruciate ligament reconstruction in goats.

Background: Several problems have been reported with use of allogenic grafts in anterior cruciate ligament reconstruction, including local immune response to allograft tendon within the synovial fluid, delayed maturation and ligamentization, and progressive tibial tunnel enlargement.

Hypothesis: There is a correlation between the use of allograft and tibial tunnel enlargement.

Study Design: Controlled laboratory study.