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Objectives This study aimed to describe the length, internal and external diameters, cancellous bone volume and extent, and cortical thickness at predetermined locations in the radius and ulna of a cohort of skeletally mature, disease-free feline cadavers using radiography and computed tomography (CT). Methods Five feline cadavers were used (mean weight 3.31 kg, range 2.55–4.24 kg). Antebrachii (n = 10) were radiographed to confirm skeletal maturity and normal radiographic appearance prior to CT. Reconstructed CT images were used to measure bone length, cortical thickness, internal and external diameters, and cancellous extent. Cancellous bone volume was calculated automatically using OsiriX after manual segmentation (350–850 Hounsfield units window) from axial CT slices. Results CT images were used to measure bone length, cortical thickness, internal and external diameters, and cancellous extent and volume. Mean radial length was 95.89 mm (95% confidence interval [CI] 88.52–103.26 mm) and mean ulna length was 114.67 mm (95% CI 105.53–123.81 mm). The olecranon had the largest mean cancellous bone volume (94.16 mm3; 95% CI 72.09–116.23 mm3) and it extended a mean of 13.12 mm (95% CI 11.73–14.51 mm) distally. The radius at the level of the trochlea and the ulna at the level of the coronoid processes had the largest external diameters, respectively. The medullary canal narrowed at the level of the coronoid processes and became cranially eccentric at the proximal third of the diaphysis. The cranial cortex at the level of the coronoid processes and the caudal cortex of the olecranon were markedly thicker than other cortices at those levels. Conclusions and relevance Morphometry of the feline antebrachium was described using CT, and should be a useful reference for future research investigations and clinical applications. [ABSTRACT FROM AUTHOR]

Objective:  The aim of the study was to determine the effect of a short and long working length screw configuration on construct stiffness and plate strain in a synthetic, short fragment, small gap fracture model stabilized with a 12-hole 3.5-mm locking compression plate (LCP)., Study Design:  Six replicates of short and long working length constructs on a short fragment, small gap fracture model underwent four-point bending. Construct stiffness and plate strain were compared across working length and along the plate., Results:  With the LCP on the compression surface (compression bending), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Conversely, with the LCP on the tension surface (tension bending), transcortical contact between 150 and 155 N induced load sharing at the fracture gap, which significantly increased construct stiffness and decreased plate strain in the long working length. At 100 N (precontact), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length, comparable with our compressing bending results., Conclusion:  In compression bending, and before transcortical contact occurred in tension bending, the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Load sharing due to transcortical contact observed in our model in tension bending will vary with fracture gap, working length, and loading condition. These results must be interpreted with caution when considering clinical relevance or potential in vivo biomechanical advantages., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective:  To evaluate the effect of 3.5-mm locking compression plate (LCP) length on construct stiffness and plate and bone model strain in a synthetic, short-fragment, fracture-gap model., Study Design:  Six replicates of 6-hole, 8-hole, 10-hole, and 12-hole LCP constructs on a short-fragment, tubular Delrin fracture gap model underwent four-point compression and tension bending. Construct stiffness and surface strain, calculated using three-dimensional digital image correlation, were compared across plate length and region of interest (ROI) on the construct., Results:  The 12-hole plates (80% plate-bone ratio) had significantly higher construct stiffness than 6-hole, 8-hole, and 10-hole plates and significantly lower plate strain than 6-hole plates at all ROIs. Strain on the bone model was significantly lower in constructs with 10-hole and 12-hole plates than 6-hole plates under both compression and tension bending., Conclusion:  Incremental increases in construct stiffness and incremental decreases in plate strain were only identified when comparing 6-hole, 8-hole, and 10-hole plates to 12-hole plates, and 6-hole to 12-hole plates, respectively. Strain on the bone model showed an incremental decrease when comparing 6-hole to 10-hole and 12-hole plates. A long plate offered biomechanical advantages of increased construct stiffness and reduced plate and bone model strain, over a short plate in this in vitro model., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective: To describe the diagnosis, management, and outcome of a dog with a right distal radial osteochondroma that penetrated the ulna, causing expansile lysis and fracture., Animal: A 9-month-old entire female German Shorthaired Pointer., Clinical Presentation, Progression, and Procedures: The dog had a 2-month history of weight-bearing lameness of the right forelimb and a 2-week history of a progressively enlarging, firm swelling on the distolateral antebrachium. Computed tomography was used to characterize the lesion and for surgical planning., Treatment and Outcome: A distal ulnar ostectomy removed the affected ulnar segment, and the radial osteochondroma was excised with rongeurs. The dog was sound at 2, 16, and 45 weeks postoperatively. Radiographs at 45 weeks showed a persistent ulnar ostectomy gap with irregular but smoothly marginated edges and focal cortical irregularity at the site of radial osteochondroma excision. There was no evidence of osteochondroma recurrence., Clinical Relevance: This is a newly recognized presentation of an osteochondroma penetrating the cortex of an adjacent bone in a dog resulting in expansile lysis and cortical fracture. Computed tomography was important in diagnosis and surgical planning, and surgical treatment was successful in removing the osteochondroma and ulnar lesion. This case provides long-term radiographic and clinical follow-up after osteochondroma excision and contributes to the current knowledge on prognosis following osteochondroma excision in dogs.

Objective:  The aim of this study was to compare stiffness and strain of an in vitro fracture-gap model secured with a primary 3.5-mm locking compression plate (LCP) at three primary plate working lengths without and with an orthogonal 2.7-mm LCP., Study Design:  Primary plate screw configurations modeled short working length (SWL), medium working length (MWL), and long working length (LWL) constructs. Construct stiffness with and without an orthogonal plate during nondestructive four-point bending and torsion, and plate surface strain measured during bending, was analyzed., Results:  Single plate construct stiffness was significantly, incrementally, lower in four-point bending and torsion as working length was extended. Addition of an orthogonal plate resulted in significantly higher bending stiffness for SWL, MWL, and LWL ( p  < 0.05) and torsional stiffness for MWL and LWL ( p  < 0.05). Single plate construct strain was significantly, incrementally, higher as working length was extended. Addition of an orthogonal plate significantly lowered strain for SWL, MWL, and LWL constructs ( p  < 0.01)., Conclusion:  Orthogonal plate application resulted in higher bending and torsional construct stiffness and lower strain over the primary plate in bending in this in vitro model. Working length had an inverse relationship with construct stiffness in bending and torsion and a direct relationship with strain. The inverse effect of working length on construct stiffness was completely mitigated by the application of an orthogonal plate in bending and modified in torsion., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective:  The aim of this study was to determine the effect of plate-bone distance (PBD) and working length on 2.0-mm locking compression plate (LCP) stiffness and strain in four-point bending and torsion in a diaphyseal fracture gap model., Study Design:  A total of 54 LCP with three screws per fragment were assigned to one of nine combinations of working length (WL; short, medium, and long), and PBD (1, 1.5, and 3 mm) for a sample size of six per construct configuration. Stiffness was measured under quasistatic, nondestructive four-point compression bending and torsion. Plate surface strain was recorded using three-dimensional (3D) digital image correlation during four-point compression bending., Results:  WL had a significant effect on overall construct stiffness in both compression bending and in torsion, with shorter WL constructs having higher stiffness ( p  < 0.0001). PBD had no effect on construct stiffness in compression bending; however, a significant reduction in stiffness was noted in torsion ( p  = 0.047) as PBD incrementally increased. WL had a significant effect on plate strain in compression bending, with shorter WL constructs having lower plate strain ( p  < 0.0001). PBD had no effect on plate strain in compression bending except for lower plate strain recorded in long WL constructs with 1-mm PBD, compared with 1.5- and 3-mm PBD constructs ( p  < 0.0001)., Conclusion:  Longer WL constructs, regardless of PBD, had lower stiffness in compression bending, while in torsion, some modulation of this effect was noted with incremental decreases in PBD. Longer WL resulted in high plate strain, regardless of PBD., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective:  This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a simple transverse juxta-articular fracture model., Study Design:  Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension non-destructive four point bending and torsion. Plate surface strain was measured at 12 regions of interest (ROI) using three-dimensional digital image correlation. Stiffness and strain were compared between screw configurations within and between each plate., Results:  The LCP was stiffer than the NHTP in all three planes of bending and torsion ( p  < 0.05). The NHTP had greater strain than the LCP during compression bending and torsion at all ROI ( p  < 0.0005). The short working length was stiffer in all three planes of bending and in torsion ( p  < 0.05) than the longer working length for both plates. The long working length showed greater strain than the short working length at most ROI., Conclusion:  In this experimental model, a 2.0 mm LCP with two screws in the short fragment was significantly stiffer and had lower plate strain than a 2.0 mm NHTP with three screws in the short fragment. Extending the working length significantly reduced construct stiffness and increased plate strain. These findings may guide construct selection., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective:  The main purpose of this study was to investigate the effect of a decrease in the A-frame angle of incline on the vertical and cranio-caudal ground reaction forces observed in a homogeneous cohort of agility dogs during entrance and contact with the A-frame., Materials and Methods:  A crossover study design was applied to eight large breed dogs to compare the vertical and cranio-caudal ground reaction forces entering the A-frame at three angles of incline: 40° (standard), 35° and 30°. The peak vertical force, passive impact peak, peak propulsive force, peak braking force, the time point (percentile) in the stance phase at which these events occurred and the proportion of time for limb contact spent in braking (% braking) and propulsion (% propulsion) were examined.The variables measured from three trials at each incline were evaluated for a significant effect of A-frame angle with height and velocity included as covariates., Results:  The peak propulsive force and the % propulsion were significantly higher at the 40° angle of incline compared with 30° ( p  = 0.013, p  = 0.0165 respectively) and the % braking was significantly lower at the 40° angle of incline compared with 30° ( p  = 0.0165). There was no significant effect of A-frame angle on the vertical ground reaction forces measured., Clinical Significance:  Compared with 30° incline, ascent up the A-frame at a 40° incline requires a higher propulsive force and extended time in propulsion to maintain forward movement and convert potential energy into forward kinetic energy., Competing Interests: The authors declare no conflicts of interest related to this report., (Georg Thieme Verlag KG Stuttgart · New York.)

Objective:  To evaluate the effect of tibial plateau levelling osteotomy on stifle extensor mechanism load in an ex vivo cruciate-intact canine cadaveric model., Study Design:   Ex vivo mechanical testing study., Animals:  Cadaveric canine pelvic limbs ( n  = 6)., Materials and Methods:  A 21-mm tibial radial osteotomy was performed on pelvic limbs ( n  = 6) prior to being mounted into a load-bearing limb press. The proximal tibial segment was incrementally rotated until the anatomical tibial plateau angle had been rotated to at least 1°. The proportional change in stifle extensor mechanism load between the anatomical tibial plateau angle and the neutralized (∼6.5 degrees) and over-rotated (∼1°) tibial plateau angle was analysed using a one-sample t -test against a null hypothesis of no change. A p -value ≤0.05 was considered significant., Results:  There was no significant change in the stifle extensor mechanism load from the anatomical tibial plateau angle (308 N [261-355 N]) to the neutralized tibial plateau angle (313 N [254-372 N]; p =.81), or from the anatomical tibial plateau angle to the over-rotated tibial plateau angle (303 N [254-352 N; p  = 0.67)., Conclusion:  Tibial plateau levelling osteotomy does not significantly alter stifle extensor mechanism load at either a neutralized or over-rotated tibial plateau angle in our cruciate-intact model., Competing Interests: The authors declare no conflicts of interest related to this report., (Schattauer GmbH Stuttgart.)

Objective:  This article aims to investigate the effect of a decrease in the A-frame angle of incline on the highest carpal extension angle in agility dogs., Methods:  Kinematic gait analysis (two-dimensional) measuring carpal extension was performed on 40 dogs entering the A-frame at 3 angles of incline: 40° (standard), 35° and 30°. The highest carpal extension angle from three trials at each incline was examined for a significant effect of A-frame angle with height, body weight and velocity included as covariates., Results:  There was no significant effect of A-frame angle on the highest carpal joint extension angle for the first or second limb. The adjusted mean carpal extension angle for the first limb at 40° was 64° [95% confidence interval (CI), 60-68), at 35° was 61° (95% CI, 57-65) and at 30° was 62° (95% CI, 59-65). The raw mean carpal extension angle for all dogs across all A-frame angles for the first limb was 62° (95% CI, 60-64) and the second limb was 61° (95% CI, 59-63)., Clinical Significance:  Decreasing the A-frame angle of incline from 40° to 30° did not result in reduced carpal extension angles. The failure to find a difference and the narrow CI of the carpal angles may indicate that the physiologic limits of carpal extension were reached at all A-frame angles., Competing Interests: The authors declare no conflicts of interest related to this report., (Schattauer GmbH Stuttgart.)

Objective: To investigate the effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs., Methods: A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Two screws per fragment modelled a long (8-hole) and short (4-hole) plate working length. Strain responses to axial compression were recorded at six regions of the plate via three-dimensional digital image correlation., Results: The addition of a pin of any size provided a significant decrease in plate strain. For the long working length, LCPR-30 and LCPR-40 had significantly lower strain than the LCPR-20, and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for the LCP-Mono and LCPR-20 constructs, but not for the LCPR-30 and LCPR-40 constructs., Clinical Significance: The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30-40% intramedullary diameter. Where placement of a large diameter pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.