Effect of Excess Fluoride Exposure on Radiographic and Histopathological Changes in Long Bones of Rabbit.

The present study aimed to investigate the effects of excess fluoride exposure on long bones in young rabbits (Oryctolagus cuniculus). New Zealand White rabbits (n = 30) were randomly divided into five equal groups and were provided drinking water containing 0, 50, 100, 200, and 400 µg added fluoride per ml ad lib for a period of 90 days. Blood samples were collected on days 0, 45, and 90 of the experiment, and femur samples were collected for fluoride estimation on day 90 after radiography of long bone before sacrifice. Study revealed significant increase in serum fluoride concentration following oral intake of excess fluoride. Alterations in activities of alkaline phosphatase, aspartate transaminase, alanine transaminase, and concentrations of creatinine and urea nitrogen in blood plasma were also recorded in animals receiving excess fluoride, though changes revealed inconsistent pattern. Radiographic changes in long bones in fluoride exposed rabbits included widening of metaphysis, thinning of cortical region, and a variety of osteopenic changes like osteoporosis and osteomalacia that were more prominent in animals receiving 200 ppm or more than 200 ppm fluoride in drinking water. Important changes in histomorphology of growth plate in long bones recorded in excess fluoride (> 100 ppm) exposed rabbits included irregular thickening of epiphyseal growth plate with haphazard orientation of chondrocytes forming nodular protrusion into metaphysis. Fluoride exposure induced both osteogenesis and osteoporosis to a degree varying with dose of fluoride exposure.

Biomechanical properties of a novel locking compression plate to stabilize oblique tibial osteotomies in buffaloes.

OBJECTIVE: Quantitation of mechanical properties of a novel locking compression plate (LCP) for bovine tibia. STUDY DESIGN: Prospective in vitro study. SAMPLE POPULATION: Adult Murrah buffalo (250-350 kg) tibiae. METHODS: Forty tibiae were randomly assigned to five treatment groups (n = 8/group): intact bone and bone constructs with a standard nonlocking plate, single LCP, double LCP, and novel LCP. During implant application, a mid-diaphyseal, oblique osteotomy was performed in all constructs, which were subsequently tested in axial compression (n = 4 each) or three-point craniocaudal bending (n = 4 each). Novel LCP alone (n = 4) was tested only in bending. Stiffness, yield load, ultimate failure load, and bending moment were determined from the load deformation curves and compared among different treatment groups (P < .05). RESULTS: Under compression, yield load of the novel LCP (24.07 ± 3.45 kN) was greater than that of the nonlocking plate (11.10 ± 2.46 kN) and the single LCP (18.01 ± 2.07 kN) but less than that of the double LCP (30.61 ± 1.95 kN), and ultimate failure load of the novel LCP (25.85 ± 4.32 kN) was greater than that of the nonlocking plate (13.18 ± 2.91 kN) but similar to that of the single LCP (21.17 ± 2.33 kN) and the double LCP (32.40 ± 1.46 kN). Bending moment, yield load, and ultimate failure load of the novel LCP were 565.37 ± 79.30 Nm, 7.90 ± 1.14 kN, 9.83 ± 1.38 kN, respectively, which were greater than those of the nonlocking plate and the single LCP but comparable to those of the double LCP. CONCLUSION: The novel LCP developed for bovine tibia was mechanically superior to the standard nonlocking plate or the single LCP and comparable to the double LCP. CLINICAL SIGNIFICANCE: The novel LCP may provide rigid fixation of tibial diaphyseal fractures in buffaloes and cattle weighing 250 to 350 kg.

Allogeneic mesenchymal stem cells and growth factors in gel scaffold repair osteochondral defect in rabbit.

Aim: An attempt was made to improve osteochondral healing with allogeneic mesenchymal stem cells (MSCs) along with certain growth factors. Materials & methods: Induced knee osteochondral defects were filled as: phosphate buffer saline (group A); MSCs in collagen gel (group B); group B plus insulin like growth factor-1 (group C); group C plus transforming growth factor ß-1 (group D). Results: Gross and scanning electron microscopy showed superior morphology and surface architecture of the healed tissue in groups D and C. Histologically, group D revealed hyaline cartilage characteristic features followed in order by group C and group B. In all treatment groups, chondrogenic matrix, collagen II2B (col II 2B) and aggrecan were secreted. Conclusion: Combined use of MSCs and growth factors could accelerate osteochondral healing.

Mesenchymal stem cells with IGF-1 and TGF- ß1 in laminin gel for osteochondral defects in rabbits.

OBJECTIVE: Healing of articular cartilage is still a challenge due to its limited potential to regenerate. In the present study, we evaluated allogenic bone marrow mesenchymal stem cells (BM-MSCs) alone or in combination with growth factors, insulin-like growth factor-1 (IGF-1) and transforming growth factor-ß1 (TGF-ß1) in laminin scaffolds for healing of osteochondral defects. DESIGN: Osteochondral defects of 4mm (diameter) x 5mm (depth) were induced in the rabbit knee joints and treated with phosphate-buffered saline (PBS; control), BM-MSCs, BM-MSCs in laminin, BM-MSCs in laminin with IGF-1, or BM-MSCs in laminin with IGF-1 and TGF-ß1 in 10 animals each. Gross, radiographic, scanning electron microscopic (SEM) and histologic examinations besides chondrocyte-specific genes expression by quantitative real time qPCR were carried out at 8 and 12 weeks. RESULTS: Gross and SEM examination revealed superior morphology and surface architecture of the healing site in animals that received MSCs with IGF-1 or IGF-1 and TGF-ß1. The application of laminin composites containing MSCs with IGF-1 and TGF-ß1 significantly enhanced hyaline cartilage formation with improved cellular arrangement, proteoglycan deposition, clear tidemark zone and subchondral bone formation. However, regenerated tissue in defects that received only MSCs had poor tidemark zone and proteoglycans deposition Aggrecan and Coll2 expression was significantly higher in case of MSCs with growth factors. CONCLUSION: The treatment with BM-MSCs combined with IGF-1/TGF-ß1 into laminin gel scaffold might enhance the restoration of hyaline cartilage in osteochondral defect.

Guinea pigs as an animal model for sciatic nerve injury.

The overwhelming use of rat models in nerve regeneration studies is likely to induce skewness in treatment outcomes. To address the problem, this study was conducted in 8 adult guinea pigs of either sex to investigate the suitability of guinea pig as an alternative model for nerve regeneration studies. A crush injury was inflicted to the sciatic nerve of the left limb, which led to significant decrease in the pain perception and neurorecovery up to the 4th weak. Lengthening of foot print and shortening of toe spread were observed in the paw after nerve injury. A 3.49 ± 0.35 fold increase in expression of neuropilin 1 (NRP1) gene and 2.09 ± 0.51 fold increase in neuropilin 2 (NRP2) gene were recorded 1 week after nerve injury as compared to the normal nerve. Ratios of gastrocnemius muscle weight and volume of the experimental limb to control limb showed more than 50% decrease on the 30th day. Histopathologically, vacuolated appearance of the nerve was observed with presence of degenerated myelin debris in digestion chambers. Gastrocnemius muscle also showed degenerative changes. Scanning electron microscopy revealed loose and rough arrangement of connective tissue fibrils and presence of large spherical globules in crushed sciatic nerve. The findings suggest that guinea pigs could be used as an alternative animal model for nerve regeneration studies and might be preferred over rats due to their cooperative nature while recording different parameters.

Comparative evaluation of in vitro mechanical properties of different designs of epoxy-pin external skeletal fixation systems.

OBJECTIVES: To compare in vitro biomechanical properties of different designs of epoxy-pin external skeletal fixator (ESF) constructs. STUDY DESIGN: Mechanical testing study. SAMPLE POPULATION: Four epoxy-pin ESF design constructs (uniplanar [EU], multiplanar-I [EM-I], multiplanar-II [EM-II], and circular [EC]) were mechanically tested in compression, bending, and torsion. METHODS: Four different designs of free-form epoxy-pin external fixator constructs were developed using 1.5 mm K-wires and epoxy resin mounted in an ultra-high density polyethylene rod (20 mm diameter). Three-point fixation was done in each fragment, and the distance between fixation wires, and between the rod and the side bars was kept constant in all the designs. A 5 mm gap was maintained at the center of the fixation rod to simulate an unstable fracture condition. The fixator constructs (n = 12 of each design) were subjected to mechanical testing in axial compression, bending, or torsion. Load-deformation curves were generated and mechanical properties were compared between construct types. RESULTS: EU was the weakest design. Under compression, constructs EM-I, EM-II, and EC were similar. Under bending, EM-I and EM-II had similar strength, whereas EC was strongest. Under torsion, EC was strongest, followed by EM-II, EM-I, and EU; EM-II provided double the rotational stability of EM-I. CONCLUSIONS: Overall, EC followed by EM-II epoxy-pin fixator designs had better mechanical strength.

Effect of IGF-1 and Uncultured Autologous Bone-Marrow-Derived Mononuclear Cells on Repair of Osteochondral Defect in Rabbits.

OBJECTIVE: To investigate the utility of bone-marrow-derived mononuclear cells (BMNCs) and insulin like growth factor-1 (IGF-1) in articular cartilage repair. DESIGN: An osteochondral defect of 3 mm diameter and 5 mm depth was created in patellar groove of the left knee joint in each of 36 New Zealand White rabbits. The defect was filled with RPMI-1640 medium in group A (control), autologous BMNCs in group B, and autologous BMNCs plus IGF-1 in group C (n = 12). Healing of the defect was assessed by gross, scanning electron microscopic, radiographic, and histological examinations up to 90 days. RESULTS: Gross and scanning electron microscopic examination of the healing site revealed superior gross morphology and surface architecture of the healing tissue in the animals of group C as compared to other groups. Radiographically on day 90, the defect area was not distinguishable from the surrounding area in group C, but a small circular defect area was still evident in groups A and B. The regenerated tissue was mostly hyaline in group C and fibrocartilage in groups A and B. The cells were well organized and showed better deposition of proteoglycans in groups C and B than in group A. CONCLUSIONS: It was concluded that implantation of bone-marrow-derived nucleated cells may facilitate the healing of osteochondral defects; however, the combination of BMNCs and IGF-1 induces faster and histologically better healing than the BMNCs alone.

Management of tibial fractures using a circular external fixator in two calves.

OBJECTIVES: To report the repair of tibial diaphyseal fractures in 2 calves using a circular external skeletal fixator (CEF). STUDY DESIGN: Clinical report. ANIMALS: Crossbred calves (n=2; age: 6 months; weight: 55 and 60 kg). METHODS: Mid-diaphyseal tibial fractures were repaired by the use of a 4-ring CEF (made of aluminum rings with 2 mm K-wires) alone in 1 calf and in combination with hemicerclage wiring in 1 calf. RESULTS: Both calves had good weight bearing with moderate lameness postoperatively. Fracture healing occurred by day 60 in 1 calf and by day 30 in calf 2. The CEF was well maintained and tolerated by both calves through fracture healing. Joint mobility and limb usage improved gradually after CEF removal. CONCLUSIONS: CEF provided a stable fixation of tibial fractures and healing within 60 days and functional recovery within 90 days. CLINICAL RELEVANCE: CEF can be safely and successfully used for the management of selected tibial fractures in calves.

In vitro biomechanical properties of linear, circular, and hybrid external skeletal fixation devices for use in large ruminants.

OBJECTIVE: To report the biomechanical properties of 3 external skeletal fixation (ESF) devices for use in large ruminants. STUDY DESIGN: In vitro biomechanical testing of ESF constructs. SAMPLE POPULATION: Adult buffalo (weighing, 250-350 kg) tibiae (n=27). METHODS: ESF constructs (bilateral linear fixator [BLF], 4-ring circular external fixator [CEF], and hybrid fixator [HF]) were made using mild (low carbon) steel implants plated with nickel and cadaveric buffalo tibiae. After ESF application, a 1 cm mid-diaphyseal gap was created. Constructs were loaded to failure, on a materials testing machine, in axial compression (n=5/ESF type) and craniocaudal bending (n=3/ESF type). In addition, 3 CEF constructs were tested in intact tibiae under craniocaudal bending. RESULT: In compression, HF was the strongest and most rigid construct; yield load was significantly higher for HF than for BLF or CEF. Under bending, both CEF and HF had similar strength and modulus of elasticity. Strength for BLF was higher than CEF and HF, whereas the reverse was true for modulus of elasticity. CONCLUSIONS: ESF made from mild steel for use in large ruminants could withstand

Evaluation of two dynamic axial fixators for large ruminants.

OBJECTIVES: To evaluate healing of a radial osteotomy repaired by application of dynamic axial fixation devices (DAF) in large ruminants. STUDY DESIGN: In vivo study of bone healing after application of 2 DAF types. Model I had 2 sidebars, each with a central cylindrical cuff (internally threaded) with 2 detachable connecting rods telescoping within the cuff. Model II had 2 side bars with 2 moveable clamps with multiple holes. SAMPLE POPULATION: Bull calves (n=8; aged, 1.5-2.0 years; weighing, 175-250 kg). METHODS: A mid-diaphyseal radial osteotomy was repaired by use of a model I (n=4) or model II (n=4) DAF. Calves were monitored for weight bearing, stability of fixation, and radiographically for fracture reduction, alignment and healing at intervals for 6 months. Fixators were removed when there was radiographic evidence of healing. RESULTS: Both the fixators were well tolerated with free movement of adjacent joints. Fragment fixation was maintained until healing in all but 1 model I calf where failure occurred within 7 days. Model II DAF provided more rigid fixation as indicated by early full weight bearing and fracture healing with less callus formation. Functional recovery of repaired limbs occurred within 60 days in surviving calves. CONCLUSIONS: Both bilateral DAFs were easy to apply; however, the model II DAF provided better fixation. CLINICAL RELEVANCE: The model II DAF made of low carbon steel was economical and may be useful for treating long bone fractures in large ruminants.