Magnusson L-E, Ekman S: Osteoarthrosis of the antebrachiocarpal joint of 7 riding horses. Acta vet. scand. 2001, 42, 429-434.-Osteoarthrosis (OA) of the antebra-chiocarpal joint from 7 riding horses is described. The horses were old mares and developed severe OA, with ankylosis in some of the joints. The lesions were bilateral, and the owners noticed the lameness in a late event. The cause of severe OA in these mares is not clear. The fact that OA was bilateral indicates that a single traumatic injury is unlikely as an etiologic factor. Considering the severe joint lesions it took long time before the horse-owners noticed the lameness. It is discussed if the threshold of pain is higher in the antebrachiocarpal joint compared with the middle carpal joint.

Extending the carpus results in internal rotation, and proximal translation of the radius relative to the ulna. Loading the carpus in extension decreases the internal and external rotation of the radius relative to the ulna. A better understanding of the interaction between the carpus and the elbow may improve our understanding of the pathogenesis of elbow dysplasia.

Objective The aim of this study was to evaluate the contribution of the palmar radiocarpal ligament and the palmar ulnocarpal ligament to canine antebrachiocarpal joint stability. Materials and Methods The right carpus of four dog cadavers, free of musculoskeletal pathology, was stripped of muscle. Each specimen was placed into a custom-made joint testing machine and tested at 15° extension, and 0° and 15° flexion. A single motion tracking sensor was fixed to the metacarpal bones. All specimens were tested with all ligaments intact and after transection of the palmar radiocarpal and ulnocarpal ligaments. A range of weights between 0.2 and 2.0 kg was used to test the carpi in three directions (axial, medial/lateral and cranial/caudal) and two moments (pronation/supination and valgus/varus). Results No differences were found between the translations and rotations of the manus relative to the radius and ulna with the ligaments intact and the ligaments transected at any of the carpal angles tested, except at 15° of flexion. Increasing the angle of flexion resulted in a significant increase in cranial and caudal translation of the manus relative to the radius and ulna both in the intact and transected specimens. Clinical relevance Antebrachiocarpal joint position plays a more important role in craniocaudal antebrachiocarpal joint stability than the palmar radiocarpal and ulnocarpal ligaments.

Objective: To evaluate the effect of tibial plateau leveling osteotomy (TPLO) and tibial tuberosity transposition (TTA) on craniocaudal stability of the cranial cruciate ligament (CCL) deficient stifle at 3 joint angles. Study design: Ex vivo biomechanical study. Sample population: Eight stifles from 4 dogs. Methods: One of the hind limbs was randomly assigned to undergo TPLO or TTA, with the contralateral limb assigned to the alternate procedure. Each specimen was tested with the stifle at 150 , 135 , and 120 of flexion. Cranial translation of the tibia relative to the femur was measured under cranial loads ranging from 0.2 to 2.0 kg with a single motion tracking sensor (Nest of Birds) fixed to the tibia. Each stifle was tested before and after transection of the CCL and after performing the assigned procedure. Results: Tibial plateau leveling osteotomy and TTA caused a decrease in the cranial translation of the tibia relative to the femur, especially at greater angles of flexion. Tibial plateau leveling osteotomy caused a greater decrease in tibial cranial translation and was associated with a degree of translation that did not differ from joints with intact CCL, regardless of the degree of stifle flexion. Conclusion: Tibial plateau leveling osteotomy and TTA caused an angle dependent decrease in craniocaudal translation of the tibia in the CCL deficient stifle. Only TPLO restored translations similar to those of the intact joint at all angles tested. Clinical impact: Tibial plateau leveling osteotomy and TTA provide passive stability to the stifle. Tibial plateau leveling osteotomy seems more effective than TTA at restoring craniocaudal stability of the stifle.

Objective The aim of this study was to develop a three-dimensional (3D) model to identify the isometric component of the cranial cruciate ligament (CCL) in dogs. Methods A static 3D model of the specimen was generated from a computed tomography scan of the stifle of a dog and a kinematic model was generated from data collected, every 5 degrees from full extension (131 degrees) through 80 degrees of stifle flexion, from four sensors attached to the tibia. Kinematic data were superimposed on the static model by aligning the points of interest, which were defined for both models. This allowed the tibia to rotate and translate relative to the femur based on the kinematic data. The contours of the distal femur and proximal tibia were converted into point clouds and the distance between each point in the femoral point cloud and all the points in the tibial point cloud were measured at each of the 15 positions. The difference between the maximum and minimum distances for each pair of points was calculated, and when it was less than 0.2 mm, points were illustrated as two red dots connected by a line at their locations on the femur and tibia. Results A total of 3,681 pairs of isometric points were identified and were located at the origin and insertion of the CCL and on the lateral aspect of the stifle. Conclusion Isometric areas are present at the origin and insertion of the CCL and lateral aspect of the stifle. Better understanding of these locations may lead to refinements in techniques to replace the ruptured CCL.