Comparison of bone healing,as assessed by computed tomography,following tibial tuberosity advancement in dogs with and without autogenous cancellous bone grafts

Abstract

AIMS: To objectively compare measures of bone healing, using computed tomography (CT) in dogs following bilateral tibial tuberosity advancement (TTA), between tibiae treated with and without autogenous cancellous bone grafts.

METHODS: Ten dogs with bilateral cranial cruciate ligament disease requiring surgical stabilisation were prospectively recruited to undergo single-session bilateral TTA, with only one, randomly assigned, tibia receiving bone graft in the osteotomy deficit. Bone healing at the osteotomy site was assessed using CT performed 38–70 days post-operatively. CT images were evaluated using both objective measurements of osseous bridging and subjective evaluation by six radiologists. Repeated measures ANOVA was used to compare the objective outcomes between the grafted and non-grafted tibiae.

RESULTS: The mean percentage of the osteotomy deficit bridged at the lateral cortex was greater in grafted (77.6, SD 35.2%) compared to non-grafted (63.0, SD 36.5%) tibiae (p=0.001), but did not differ at the medial cortex (p=0.1). The mean minimum callus width was greater in grafted (7.2, SD 3.3 mm) compared to non-grafted (3.6, SD 2.9 mm) tibiae (p<0.001). There was no difference in mean attenuation (measured in Hounsfield units) of the callus between grafted and non-grafted tibiae (p=0.5). The grafted tibia was deemed to have superior bone healing in 50/60 subjective assessments made by radiologists.

CONCLUSIONS: Superior osseous bridging was detected by CT analysis following TTA using autogenous cancellous bone grafts compared with no graft. This was shown by greater bridging percentage at the lateral cortex and formation of a broader callus. Qualitative assessments made by six radiologists also supported the conclusion that bone healing was improved by use of autogenous cancellous bone graft. CT was a useful method for assessing evidence of bone healing following TTA.

CLINICAL RELEVANCE: These findings justify the application of autogenous cancellous bone graft to augment healing following TTA in dogs.     

Congenital malformations of the external and middle ear accompanied by temporal bone anomaly in a calf

A 7-month-old female Holstein calf presented with bilateral microtia and absent external acoustic meatus. The real-time polymerase chain reaction test was negative for bovine viral diarrhea virus and bovine leukemia virus. The calf’s dam had a normal reproductive history. Computed tomography confirmed bilateral atresia of external auditory canals, aplasia of tympanic cavities and the ossicular chain, and temporomandibular joint abnormality. Necropsy revealed a severe malformation of the temporal bone. In the tympanic region, the external acoustic pore, tympanic bulla, and muscular process were absent bilaterally. The bilateral inner ear structure was normal. Based on these findings, we diagnosed the present case as congenital malformations of the external and middle ear accompanied by temporal bone anomaly.     

Guided bone regeneration with beta-tricalcium phosphate and poly L-lactide-co-glycolide-co-epsilon-caprolactone membrane in partial defects of canine humerus

This study was performed to evaluate the effect of beta-tricalcium phosphate and poly L-lactide-co-glycolide-co-epsilon-caprolactone (TCP/PLGC) membrane in the repair of partial bone defects in canine proximal humerus. Three adult mixed-breed dogs were used during the experimental period. The length of the defect was quarter of the full length of humerus, and width of the defect was quarter of middle diameter of the lateral aspect of humerus. The humeri of each dog were divided into treatment (TCP/PLGC) and control groups. The defect was covered with TCP/PLGC membrane in treatment group. To evaluate regeneration of the bone, computerized tomography (CT) and histopathologic examination were performed. The radiopaque lines were appeared at the original defect sites in TCP/PLGC group but below the original site in control at 4th week. Radiopacity and thickness of the defect sites, and radiopaque lines were more increased at 8th week than those of 4th week. Histopathologic findings revealed fibrous connective tissue migration into the defect and the migration inhibited the structure of new cortex to be placed in the original level in control whereas new cortex growth was found in the level of original line in TCP/PLGC group. However, the new cortical bone in the TCP/PLGC group was thinner and less organized than the adjacent intact cortex, and the amount of new cancellous bones were also scanty. The result suggested that TCP/PLGC membrane is a good guided bone regeneration material to restore the original morphology of humerus in partial defect.     

Biomechanical comparison of orthofix pins and cortical bone screws in a canine humeral condylar fracture model

OBJECTIVE: To compare shear stability of simulated humeral lateral condylar fractures reduced with either a self-compressing pin or cortical bone screw. STUDY DESIGN: In vitro biomechanical tests. SAMPLE POPULATION: Bilateral cadaveric canine humeri (n=18) without evidence of elbow disease. METHODS: Lateral condylar fracture was simulated by standardized osteotomy. Bone fragments were stabilized with a self-compressing pin or a cortical bone screw (2.7 or 3.5 mm) inserted in lag fashion. Specimens were mounted in a materials testing system and the condylar fragment displaced in a proximal direction until failure. Mechanical testing variables derived from load-deformation curves were compared between stabilization methods using a Student's paired t-test. RESULTS: There were no statistically significant differences for mechanical testing variables between pin and screw stabilized specimens at expected walk and trot loads. Three yield points subjectively coincided with yield of the interfragmentary interface (Y1), bone at the implant interface (Y2), and implant deformation (Y3). Displacements at Y1 were 48-156% greater for pin than screw stabilized specimens. Y2 and Y3 loads were higher for screw than pin stabilized specimens, but likely supraphysiologic for dogs convalescing after surgical repair. CONCLUSIONS: A self-compressing pin or a cortical bone screw inserted in lag fashion both provided adequate strength in applied shear to sustain expected physiologic loads through the repaired canine elbow during postoperative convalescence. CLINICAL RELEVANCE: Because self-compressing pins were easy to implant and mechanical properties were not significantly different than cortical screws at expected physiologic loads, pins should be considered for the repair of traumatic humeral condylar fractures.     

Effect of supplementation of calf starter with fennel powder on performance,weaning age and fermentation characteristics in Holstein dairy calves

The objective of this experiment was to investigate the effects on performance, weaning age and rumen fermentation characteristics in Holstein calves when fennel powder was added to their starter diets. Thirty Holstein calves with a mean birth weight 40 kg (SD = 0.5) were allocated randomly to one of the following experimental diets: (i) control (starter diet without fennel powder), (ii) starter diet containing 0.4% of fennel powder and (iii) starter diet containing 0.8% of fennel powder (DM basis). The effect of treatments on mean dry matter intake was significant (p < 0.05) in the post‐weaning and total experimental periods. Average daily weight gain before (0.38, 0.49 and 0.47 kg/day) and after (0.6, 1.01 and 0.83 kg/day) weaning and during the entire study (0.45, 0.7 and 0.58 kg/day) was influenced by diets of 1, 2 and 3, respectively (p < 0.05). Maximum daily weight gain and the best feed conversion ratio were achieved with 0.4% fennel powder. Mean weaning age of the calves supplemented with fennel powder was lower (p < 0.05) than that of the control group. Ruminal fluid pH in calves offered starter containing 0.8% fennel powder was lower (p < 0.05) compared to calves fed the other diets. Ammonia nitrogen content increased (p < 0.05) in the third week of feeding fennel powder. The mean concentration of total short‐chain fatty acids (SCFA) and propionate molar percentage in the ruminal fluid of the calves fed with the fennel powder were higher (p < 0.05) at 6 weeks and 2 weeks after weaning than control group; however, acetate‐to‐propionate molar ratio was lower (p < 0.05). The results showed that adding 0.4% fennel powder to the starter increased the propionate molar percentage in the rumen and improved the calf performance, allowing the calves to be weaned at an earlier age.     

Repair of radial fractures in toy breed dogs with self-reinforced biodegradable bone plates, metal screws, and light-weight external coaptation

OBJECTIVE: To describe a surgical technique for, and outcome after, treatment of radial fractures with biodegradable self-reinforced polylactide plates and metal screws, and external coaptation. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Eleven Toy breed dogs. METHODS: Radial fractures were repaired by application of a single or 2 stacked biodegradable self-reinforced polylactide plates (poly-L/D, L-lactide, stereocopolymer [LL-and DL-lactide ratio 70/30]; SR-PLA (70/30) implants) secured with metal screws, and light-weight external coaptation. Healing was evaluated clinically and by radiography at 2, 4, 6, 8, 9, 12, 24-26 weeks, and at 1 and 2 years. Owners were interviewed 3 years after surgery. RESULTS: Radial fracture lines disappeared within 4-14 weeks in 10 dogs; an implant failed in 1 dog. Ambulation was excellent for healed fractures. Excessive skin tension led to removal of implants in 1 dog and suture repair in another dog. No foreign body reaction from implant degradation was observed and the plate was usually no longer palpable at 2 years. One dog had a fracture through a screw hole at 1 year. CONCLUSION: Healing and complication rates after repair of radial fractures with SR-PLA (70/30) plates were considered similar or better than reported after repair with metallic plates or external fixation in Toy breed dogs. No radiographic signs of osteopenia were identified under the plate during follow-up. CLINICAL RELEVANCE: Biodegradable polylactide plates could be considered as an alternative to metal plates for radial fracture repair in Toy breed dogs, however available plates are likely not strong enough when used as a single plate. Implant removal is usually not needed.     

Quantities of ash,Ca, and P in metacarpals,metatarsals, and tibia are better correlated with total body bone ash in growing pigs than ash,Ca, and P in other bones

The objective was to determine correlations between individual bones and total body bone ash to identify the bone that is most representative of total body bone ash in growing pigs. Twenty growing pigs were allotted to 1 of 2 diets that were formulated to contain 60% or 100% of the requirement for standardized total tract digestible (STTD) P. Both diets had an STTD Ca to STTD P ratio of 1.90:1. Growth performance and carcass weights were determined. Metacarpals, metatarsals, femur, tibia, fibula, 3rd and 4th ribs, and 10th and 11th ribs, and all other bones from the left half of the carcass were collected separately. Each bone was defatted and ashed. Pigs fed the diet containing 100% of required Ca and P had greater (P < 0.05) average daily gain, gain to feed, and ash concentration (%) in total and all individual bones except femur and fibula compared with pigs fed the diet containing 60% of required Ca and P. Calcium and P concentrations in bone ash were not affected by dietary treatments. Weights (g) of bone ash, bone Ca, and bone P were greater (P < 0.05) or tended to be greater (P < 0.10) for pigs fed the diet containing 100% of required Ca and P. Correlation coefficients between the weight of ashed metacarpals, metatarsals, and tibia and the weight of total bone ash were >0.95. In conclusion, metacarpals, metatarsals, and tibia were more representative of total body bone ash compared with other bones.     

Evaluation of platelet count and its association with plateletcrit, mean platelet volume, and platelet size distribution width in a canine model of endotoxemia

BACKGROUND: Platelets are of great importance in the pathogenesis of endotoxemia. Although thrombocytopenia is used as a diagnostic sign of endotoxemia, changes in values for platelet indices (plateletcrit [PCT], mean platelet volume [MPV], and platelet size distribution width [PDW]) in response to endotoxin are still unknown. OBJECTIVE: The aim of this study was to evaluate platelet count and its relations with platelet indices in a canine model of endotoxemia. Methods: Twenty dogs were divided into 2 groups of 10 each, and treated intravenously with Escherichia coli endotoxin (1 mg/kg) or vehicle. Venous blood samples were collected before treatment (0 hour) and 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after treatment. Platelet counts and indices were determined on a CELL-DYN hematology analyzer. RESULTS: The platelet count and PCT decreased by a mean of 73% and 93%, respectively (P<.001), at 0.5 hour, and remained 70% and 85% lower than baseline values (P<.001) for 24 hours after endotoxin injection. MPV and PDW increased by a mean of 28% and 45%, respectively (P<.01), at 0.5 hour, and remained increased by 7% and 16% over baseline values for 24 hours (P<.01-.001). Platelet count correlated positively with PCT (P<.001), but correlated negatively with MPV (P<.001) and PDW (P<.01). CONCLUSIONS: Changes in platelet count and its association with platelet indices may reflect changes in platelet production and reactivity. Platelet indices have potential value in the diagnosis and monitoring of dogs and humans with endotoxemia.