Dysplastic hips in young dogs were significantly improved by JPS.

Hip joint laxity was evaluated in four breeds (i.e., greyhound, Labrador retriever, Irish setter, hound mixed-breed) of puppies (n=32) by Ortolani's and Bardens' maneuvers, by subjective assessment of radiographs (Orthopedic Foundation for Animals [OFA] method), and by four radiographic measurement indices. Puppies were studied at four, six-to-10, 16-to-18, and 52 weeks of age. The purpose of this study was to compare palpation and radiographic methods of hip laxity detection in puppies for predicting the development of degenerative joint disease (DJD) by one year of age. Twenty-seven (42%) hips developed DJD. Ortolani's method was not a reliable predictor of hip dysplasia at six-to-10 weeks; it was significantly predictive at 16-to-18 weeks but had a high incidence of false negatives. Bardens' and subjective (OFA) assessment methods were not reliable at six-to-10 or 16-to-18 weeks. Radiographic measurements taken with femurs in a neutral position and hips distracted (distraction index [DI] and Norberg angle) and measurements taken with femurs extended in OFA position (Norberg angle) of six- to 10-week-old puppies accurately predicted DJD occurrence by one year of age (p less than 0.01). Distraction index measurement (PennHIP method) was the most accurate in predicting the development of DJD (p less than 0.001). Distraction index radiography in puppies six-to-10 and 16-to-18 weeks of age was the most reliable predictor of hip dysplasia. Norberg angle measurement was more reliable during hip distraction than when hips were measured in the OFA position in 16- to 18-week-old puppies, but had similar reliability in six- to 10-week-old puppies.

Using standard material testing techniques (bending stiffness, torsional stiffness, and maximum torque to failure or yield torque), the structural properties of interlocking nails (IN), canine femora, and IN/femur constructs were determined. Specimens that were tested included: 6 and 8 mm diameter IN with 5 to 10 screw holes (n = 18), and intact canine femora (n = 10), which also, with an IN inserted, formed the intact construct (IC) group, (n = 10). Specimens in the IC group were first tested with an 8 mm diameter IN with zero screws, followed by one and two screws (4.5 mm diameter) in the proximal and distal femur. A fracture model construct (FMC), (n = 14), consisting of a transverse femoral osteotomy with a 3 mm gap, was used with either 6 mm or 8 mm IN. In the 6 mm FMC, one and two 3.5 mm screws were used sequentially in the proximal and distal femoral segment. In the 8 mm FMC, one and two 3.5 mm screws and one and two 4.5 diameter screws were used similarly. When bending forces were applied parallel to IN screw holes, mean IN stiffness was 20% less than with forces perpendicular to the holes (n = 18), (P < .05). Eight-millimeter IN were 220% stiffer in torsion and 270% stiffer in bending than 6 mm IN (P < .05). Six-millimeter IN had approximately 32% of the bending stiffness and torsional stiffness of intact femurs (P < .05). Eight-millimeter IN had 93% and 79% of the bending stiffness and torsional stiffness, respectively, of intact femurs. Intact femur constructs (8 mm IN with four, 4.5 mm screws) had 147% of the bending stiffness (P < .05), and similar torsional stiffness and maximum torque, as intact femora (P > .05). The mean values of 6 mm FMC with four screws (3.5 mm) were 21% and 33% in torsional stiffness and bending stiffness, respectively, of intact femora values. When tested in torsion, 8 mm FMC failed by bone fracture; 6 mm FMC, in contrast, underwent plastic deformation. In comparing FMC stabilized with an 8 mm IN with two screws (4.5 mm diameter) in each bone segment, to intact femurs, the maximum torque was similar, FMC torsional stiffness was 40% (P < .05), and FMC bending stiffness was 65% (P < .05). These 8 mm FMC percentages are comparable to human IN fracture model construct values, indicating that the 8 mm IN/four screw construct should provide adequate stabilization for many canine diaphyseal femoral fractures.