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The capacity of bone to organize and reorganize its structure in response to changing mechanical demands is well recognized. However, the mechanism by which the changing mechanical environment is detected, and the means by which this information is translated into a stimulus for structural modification, are not understood. A group of substances suggested to be involved in the initial transduction of strain information are the prostaglandins. In this experiment we used a single period of dynamic loading to stimulate an adaptive osteogenic response in vivo. Loading was performed in the presence and absence of indomethacin. Measurements of the periosteum 5 days after loading showed that the presence of indomethacin at the time of loading reduced the osteogenic response. Though consistent with the hypothesis that prostaglandins are involved in the initial transduction of tissue strain into a biochemical response, this result is not sufficient to demonstrate this conclusively because reduced prostaglandin levels during the 24 hours immediately after the period of loading may affect many other points in the cascade of events between strain transduction and adaptive new bone formation. Furthermore, indomethacin at the relatively high levels we used (40 mg/kg) may have effects other than those on prostaglandin synthesis. [ABSTRACT FROM AUTHOR]

Both ulnas of skeletally mature roosters ( Gallus domesticus) were deprived of functional load bearing by proximal and distal submetaphyseal osteotomies. Twenty-four hours later the animals were injected with 1.5 mCi ofH-uridine and the ulna on one side was subjected to a single period of a cyclical load engendering physiological strain levels at 1 Hz for 6 min. Twenty-fours after loading the animals were killed. Autoradiographic examination of comparable regions of cortex in sections from the bones' midshafts showed that in the loaded bones, 72±2.7% of osteocytes were labeled compared with 12±3.5% in the corresponding areas of their contralateral nonloaded pair ( P<0.001). The number of grains per labeled osteocyte was also higher in the loaded side (6±0.5 compared with 4±0.5, P<0.01). There was no obvious correlation between the longitudinal strain distribution during artificial loading and the distribution of labeled osteocytes throughout the bone cross-section. However, previous long-term experiments using a similar loading preparation had consistently shown the site of most periosteal new bone formation to also not be directly related to the local strain magnitude. Perhaps it is significant that the greatest percentage of labeled cells were found in the cortex where the long-term experiments had shown most new bone formation to subsequently occur. [ABSTRACT FROM AUTHOR]

Both ulnas of skeletally mature roosters (Gallus domesticus) were deprived of functional load bearing by proximal and distal submetaphyseal osteotomies. Twenty-four hours later the animals were injected with 1.5 mCi of 3H-uridine and the ulna on one side was subjected to a single period of a cyclical load engendering physiological strain levels at 1 Hz for 6 min. Twenty-four hours after loading the animals were killed. Autoradiographic examination of comparable regions of cortex in sections from the bone's midshafts showed that in the loaded bones, 72 +/- 2.7% of osteocytes were labeled compared with 12 +/- 3.5% in the corresponding areas of their contralateral nonloaded pair (P less than 0.001). The number of grains per labeled osteocyte was also higher in the loaded side (6 +/- 0.5 compared with 4 +/- 0.5, P less than 0.01). There was no obvious correlation between the longitudinal strain distribution during artificial loading and the distribution of labeled osteocytes throughout the bone cross-section. However, previous long-term experiments using a similar loading preparation had consistently shown the site of most periosteal new bone formation to also not be directly related to the local strain magnitude. Perhaps it is significant that the greatest percentage of labeled cells were found in the cortex where the long-term experiments had shown most new bone formation to subsequently occur. [ABSTRACT FROM AUTHOR]

Construct failure is a rare complication of tibial cranial closing wedge ostectomy for the management of cranial cruciate ligament disease. Construct failure can present significant challenges for reconstruction. This case report describes three dogs with construct failure which were successfully revised by the repurposing of an inverted femoral supracondylar femoral plate as part of the revision. Data were obtained from the medical records and telephone update. The use of an inverted supracondylar plate in the proximal tibia generally had good outcomes for the management of bone implant failure following cranial closing wedge ostectomy and offers a hitherto undescribed technique using a low-cost and accessible implant for repair., (© 2024 The Author(s). Journal of Small Animal Practice published by John Wiley & Sons Ltd on behalf of British Small Animal Veterinary Association.)

Objective: To establish reference intervals for radial joint orientation angles in the frontal and sagittal planes in small-breed dogs and to compare them to those previously reported for medium- and large-breed dogs., Animals: Antebrachii of 30 skeletally mature, nonchondrodystrophic small-breed dogs were evaluated radiographically., Procedures: Orthogonal radiographs were retrospectively assessed to determine the anatomic medial proximal radial angle, anatomic lateral distal radial angle, anatomic cranial proximal radial angle (aCrPRA), and anatomic caudal distal radial angle (aCdDRA). The frontal plane angle, θ angle, and procurvatum were also calculated. The radial joint orientation angles determined were compared to those previously reported for medium- and large-breed dogs via a 1-sample t test., Results: Mean and SD values for anatomic medial proximal radial angle, anatomic lateral distal radial angle, aCrPRA, and aCdDRA were 80.86 ± 2.86°, 85.60 ± 1.74°, 87.99 ± 2.79°, and 83.08 ± 3.14°, respectively. The mean and SDs for frontal plane angle, θ angle, and procurvatum were 4.75 ± 2.46°, 11.88 ± 1.76°, and 16.79 ± 4.13°, respectively. aCrPRA and aCdDRA were significantly different when compared to previously reported radial joint angles for medium- and large-breed dogs., Clinical Relevance: Reference intervals for small-breed dog radial joint orientation angles were reported. Significant differences were identified for some joint orientation angles when compared to medium- and large-breed dogs. This small-breed reference interval reported can be utilized in planning of radial angular limb deformity corrective surgery, particularly when dogs are bilaterally affected.

Backfround: Treatment options for metacarpal/metatarsal fractures include conservative and surgical management. The aim of this study is to determine whether there is any significant difference in healing and complication rates, between open and closed treatment. Medical records of dogs and cats with metacarpal/metatarsal fractures with complete follow-up were retrospectively reviewed. Patients were allocated in two groups: open or closed stabilization. Minor and major complications were recorded and compared. Fracture healing was classified as good, delayed and non-union, and it was statistically compared., Results: Sixty-three patients (35 dogs and 28 cats) were included. Thirty-one were treated with an open approach and 32 by a closed stabilization. Regarding fracture healing a significantly higher proportion of delayed healing/non-union was found in the closed group (12/32 vs 2/31). Regarding postoperative complications, a significantly higher number of animals in the open group did not develop any complications (12/31 vs 3/32). A significantly higher proportion of minor complications were reported in the closed group (27/32 vs 12/31). However, a higher number of major complications was reported in the open group (7/31 vs 2/32) although this was not statistically significant. Fracture malalignment was significantly more prevalent in patients undergoing closed stabilization (11/32 vs 2/31)., Conclusion: According to the results, better healing, fracture alignment and a lower complication rate are found when fractures are stabilised with an open technique. However, other factors such as configuration of the fracture, soft tissue involvement, patient´s character and client´s situation would also need to be taken into account in the decision of stabilization technique., (© 2022. The Author(s).)

Objective:  The aim of this study was to establish breed-standard mechanical tibial joint reference angles in the frontal plane in Dachshunds., Study Design:  Craniocaudal ( n  = 38) and mediolateral ( n  = 32) radiographs of normal tibiae from Dachshunds were retrospectively reviewed. The mechanical medial proximal, mechanical medial distal, mechanical caudal proximal and mechanical cranial distal tibial angles were measured on three occasions by two separate observers using previously established methodology. Interclass correlation coefficient was used to assess the reliability of radiographic measurements., Results:  The mean and standard deviation for mechanical medial proximal, mechanical medial distal, mechanical caudal proximal and mechanical cranial distal were 93.1 degrees ± 4.2, 97.5 degrees ± 3.9, 75.3 degrees ± 3.7 and 85.0 degrees ± 5.3 respectively. Intra-observer reliability was good to excellent for all measures, while inter-observer reliability was moderate to excellent in the frontal plane and poor to good in the sagittal plane. Dachshund-specific joint reference angles were similar to a range of previously reported non-chondrodystrophic breeds in the frontal plane but differed to most in the sagittal plane., Conclusion:  Dachshund tibial joint reference angles are reported which can be used in surgical planning for correction of bilateral pes varus., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective: To identify whether a theoretical predictable safe corridor is available in cats for placement of trans-iliac pins without the use of fluoroscopy., Methods: Twenty-one cats with straight orthogonal normal pelvic radiographs were included. Two start points were evaluated: a midpoint and a dorsal point. The midpoint was defined as midway between the dorsal lamina of the sacral vertebral canal and the cranial dorsal iliac spine. The dorsal start point was 2 mm ventral to the cranial dorsal iliac spine. The pin was assumed to be driven at 90 degrees to the lateral face of the ilium, and considered surgeon accuracy was ±4 degrees from the perpendicular. The angular range and the distance between the iliac wings from the ventrodorsal radiograph were used to calculate the possible cross-sectional area and pin exit location if driven from one iliac wing to the other. The corridor was then evaluated for repeatability in six randomly selected cats., Results: Vertebral foramina penetration risk was identified in some cats when using a 1.6 and 2 mm-diameter pin using the mid-iliac wing start point. The dorsal start point decreased the available pin placement area but reduced the risk of entering the hazardous zone for all pin sizes up to 2 mm., Conclusion and Relevance: A theoretical defined safe corridor is available for trans-iliac pin placement in cats between 2.0 and 5.5 kg. A 1.2-mm pin is the safest if using the mid-iliac wing start point. A more dorsal start point can accommodate up to a 2.0-mm pin if correctly aligned to the sacrum., (© 2021 The Authors. Australian Veterinary Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Veterinary Association.)

The objective of this study was to determine whether a novel reverse-transverse cross pin insertion technique could increase the stability of type II external skeletal fixators (ESF) in dogs compared with an alternate, same side cross pin ESF. Reverse-transverse cross pin technique and type II ESFs same side cross pin technique were applied and compared among subjects. Two of 42 ESFs (4.8%) applied with the reverse-transverse cross pin technique and 39 of 47 ESFs (83%) applied with the same side cross pin technique were subjectively unstable at the time of fixator removal (P < 0.001). The same side cross pin ESFs had significantly more pin tract new bone formation than the reverse-transverse ESFs (P = 0.038). In summary, this approach may provide a method of treating a variety of musculoskeletal conditions and soft tissue cases, which reverse-transverse cross pin ESFs are tolerated in dogs for a variety of conditions.