Long-Term Assessment of Bone Regeneration in Nonunion Fractures Treated with Compression-Resistant Matrix and Recombinant Human Bone Morphogenetic Protein-2 in Dogs.

OBJECTIVE: The aim of this study was to assess bone density, bone architecture and clinical function of canine nonunion distal appendicular long bone fractures with a defect treated with fixation, compression-resistant matrix and recombinant human bone morphogenetic protein-2 (rhBMP-2). STUDY DESIGN: Prospective cohort study with dogs at least 1-year post treatment. Computed tomography was performed and quantitative measurements from previous fracture sites were compared with measurements from contralateral limbs. Subjective evaluation included gait assessment and palpation. RESULTS: Six patients met the inclusion criteria. The rhBMP-2 treated bone exhibited higher density at the periphery and lower density in the centre, similar to the contralateral limb. All patients were weight bearing on the treated limb and all fractures were healed. CONCLUSION: The rhBMP-2-treated bone underwent restoration of normal architecture and density. Acceptable limb function was present in all patients. The results of this study can serve as a basis for long-term response in treating nonunion fractures in veterinary patients.

Results of using multiplanar reconstructed CT images for assessing elbow joint osteoarthritis in dogs are consistent with results of radiographic assessment.

OBJECTIVE: To compare osteoarthritis scores assigned through radiographic evaluation of 18 anatomic regions in the elbow joint with scores assigned through evaluation of 3-D maximum intensity projection (MIP), 3-D surface rendering (TSR), and multiplanar reconstructed (MPR) CT images, and to evaluate intraobserver and interobserver agreement of radiographic and CT scoring. SAMPLE: Radiographic and CT images of 39 elbow joints in 20 dogs. PROCEDURES: Images were anonymized and graded independently by 5 observers. One observer graded 12 elbow joints 3 times. Intraobserver consistency and repeatability, interobserver agreement, consistency among methods, and bias between methods were calculated. RESULTS: The most severe changes were observed at the proximal aspect of the anconeal process, and the medial and cranial aspects of the medial coronoid process. Intraobserver consistency was moderate or better for 11/16 regions with MIP images, 11/16 regions with TSR images, 17/18 regions with MPR images, and 14/18 regions with radiographic images. Interobserver agreement was moderate or better for 5/16 regions with MIP images, 9/16 regions with TSR images, 12/18 regions with MPR images, and 6/18 regions with radiographic images. Mean scores from CT-based methods were higher than mean radiographic scores. CLINICAL RELEVANCE: Assessments of osteoarthritis severity in the elbow joints of dogs obtained by examining radiographic images were generally consistent with assessments obtained by examining CT scans. MPR scores were more consistent and more comparable to radiographic scores than were MIP or TSR scores.

Evaluation of computer-aided design software methods for assessment of the three-dimensional geometry of the canine radius.

OBJECTIVE: To describe methods to measure the 3-D orientation of the proximal, diaphyseal, and distal segments of the canine radius by use of computer-aided design software (CADS) and to compare the repeatability and reliability of measurements derived by those methods. SAMPLE: 31 canine radii with biapical deformities and 24 clinically normal (control) canine radii. PROCEDURES: Select CT scans of radii were imported into a CADS program. Cartesian coordinate systems for the humerus and proximal, diaphyseal, and distal radial segments were developed. The orientation of each radial segment in the frontal, sagittal, and transverse planes was measured in triplicate by 3 methods. The repeatability and reliability of those measurements were calculated and compared among the 3 measurement methods. RESULTS: The mean ± SD within-subject repeatability of radial angular measurements for all 3 methods was 1.40 ± 0.67° in the frontal plane, 3.17 ± 2.21° in the sagittal plane, and 3.01 ± 1.11° in the transverse plane for control radii and 2.56 ± 1.95° in the frontal plane, 3.59 ± 2.39° in the sagittal plane, and 3.47 ± 1.19° in the transverse plane for abnormal radii. Mean ± SD bias between radial measurement methods was 1.88 ± 2.07° in the frontal plane, 6.44 ± 6.80° in the sagittal plane, and 2.27 ± 2.81° in the transverse plane. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that use of CADS to assess the 3-D orientation of the proximal, diaphyseal, and distal segments of normal and abnormal canine radii yielded highly repeatable and reliable measurements.

In vitro assessment of the motion of equine proximal sesamoid bones relative to the third metacarpal bone under physiologic midstance loads.

OBJECTIVE: To assess the motion of the proximal sesamoid bones (PSBs) relative to the third metacarpal bone (MC3) of equine forelimbs during physiologic midstance loads. SAMPLE: 8 musculoskeletally normal forelimbs (7 right and 1 left) from 8 adult equine cadavers. PROCEDURES: Each forelimb was harvested at the mid-radius level and mounted in a material testing system so the hoof could be moved in a dorsal direction while the radius and MC3 remained vertical. The PSBs were instrumented with 2 linear variable differential transformers to record movement between the 2 bones. The limb was sequentially loaded at a displacement rate of 5 mm/s from 500 N to each of 4 loads (1.8 [standing], 3.6 [walking], 4.5 [trotting], and 10.5 [galloping] kN), held at the designated load for 30 seconds while lateromedial radiographs were obtained, and then unloaded back to 500 N. The position of the PSBs relative to the transverse ridge of the MC3 condyle and angle of the metacarpophalangeal (fetlock) joint were measured on each radiograph. RESULTS: The distal edge of the PSBs moved distal to the transverse ridge of the MC3 condyle at 10.5 kN (gallop) but not at lower loads. The palmar surfaces of the PSBs rotated away from each other during fetlock joint extension, and the amount of rotation increased with load. CONCLUSIONS AND CLINICAL RELEVANCE: At loads consistent with a high-speed gallop, PSB translations may create an articular incongruity and abnormal bone stress distribution that contribute to focal subchondral bone lesions and PSB fracture in racehorses.