Mechanical evaluation of a novel angle-stable interlocking nail in a gap fracture model.

OBJECTIVE: To describe the mechanical characteristics of a novel angle-stable interlocking nail (NAS-ILN) and compare them to those of a locking compression plate (LCP) by using a gap-fracture model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Synthetic bone models. METHODS: Synthetic bone models simulating a 50 mm diaphyseal comminuted canine tibial fracture were treated with either a novel angle-stable interlocking nail (NAS-ILN) or a locking compression plate (LCP). Maximal axial deformation and load to failure in compression and 4-point bending, as well as maximal angular deformation, slack, and torque to failure in torsion, were statistically compared (P < .05). RESULTS: In compression, the maximal axial deformation was lower for NAS-ILN (0.11 mm ± 0.03) than for LCP (1.10 mm ± 0.22) (P < .0001). The ultimate load to failure was higher for NAS-ILN (803.58 N ± 29.52) than for LCP (328.40 N ± 11.01) (P < .0001). In torsion, the maximal angular deformation did not differ between NAS-ILN (22.79° ± 1.48) and LCP (24.36° ± 1.45) (P = .09). The ultimate torque to failure was higher for NAS-ILN (22.45 Nm ± 0.24) than for LCP (19.10 Nm ± 1.36) (P = .001). No slack was observed with NAS-ILN. In 4-point bending, the maximal axial deformation was lower for NAS-ILN (3.19 mm ± 0.49) than for LCP (4.17 mm ± 0.34) (P = .003). The ultimate bending moment was higher for NAS-ILN (25.73 Nm, IQR [23.54-26.86] Nm) than for LCP (16.29 Nm, IQR [15.66-16.47] Nm) (P = .002). CONCLUSION: The NAS-ILN showed greater stiffness in compression and 4-point bending, and a greater resistance to failure in compression, torsion, and 4-point bending, than LCP. CLINICAL IMPACT: Based on these results, NAS-ILNs could be considered as alternative implants for the stabilization of comminuted fractures.

Risk factors and clinical relevance of positive urine cultures in cats with subcutaneous ureteral bypass.

BACKGROUND: The objective of the study was to report the incidence and risk factors associated with positive urine bacterial cultures as well as long-term outcome in cats with subcutaneous ureteral bypass (SUB) devices. RESULTS: Medical records of cats that underwent SUB device placement were retrospectively reviewed. Signalment of the cat, laterality of the ureteral obstruction, surgery, anesthesia and hospitalization duration, bacterial culture results and follow-up data were retrieved. Thirty-two cats met the inclusion criteria. Four cats (12.5%) had a positive intraoperative culture, with two of them being treated successfully. Ten cats out of 28 (35.7%) were documented with a positive urine culture during follow-up period, with a median time between discharge and identification of the first positive urine culture of 159 days (range 8-703 days). Bacteriuria resolved in 60% of cats (6/10). Escherichia coli was the most common organism, isolated in 4 out of 10 postoperative urine cultures. Overall, subclinical bacteriura was documented for 6 of 32 (18.8%) cats and 5 of 32 (15.6%) cats displayed clinicals signs suggestive of persistent UTI. One cat had subclinical bacteriuria. Three cats died during the follow-up period. There was a significant difference between negative and positive urine bacterial culture groups in median hospitalization duration (5 days versus 6 days, P = 0.022) and in median body condition score (5/9 versus 4/9, P = 0.03). Cats with a longer hospital stay and with a lower body condition score were more likely to have a positive urine culture during follow-up period. CONCLUSIONS: SUB device placement surgery is associated with complications such as chronic bacteriuria. Bacteriuria in our study resolved with appropriate antibiotic treatment in more than half of cats. Risk factors identified for positive urine culture were a longer hospitalization duration and a decreased body condition score.

Modified Triple Tibial Osteotomy for Combined Cranial Cruciate Ligament Rupture, Tibial Deformities, or Patellar Luxation.

Proximal tibial deformities or patellar luxation may occur concurrently with cranial cruciate ligament rupture. The objective of this study was to describe the management of those conditions with a modified triple tibial osteotomy (TTO) in nine dogs. Medical records of dogs who underwent a modified TTO were reviewed. The mean pre- and postoperative patellar tendon angles were 104.2° and 92.9°, respectively. The mean pre- and postoperative mechanical medial proximal tibial angles were 99.5° and 91.5°, respectively. Medial patellar luxation was present in five dogs (55.6%) and treated in all five dogs with a tibial crest transposition. Tibial torsion was grossly resolved in two dogs (22.2%). Perioperative distal tibial crest fracture was treated by pins and a figure-of-eight tension-band wire in five dogs (55.6%). One major (surgical site infection) and three minor postoperative complications were observed. At the last follow-up, seven dogs (77.8%) had no lameness, one dog (11.1%) had mild lameness, and one dog (11.1%) had moderate lameness. Radiographic evaluation showed good (2/9; 22.2%) to excellent (7/9; 77.8%) bone healing. The visual analog scale evaluation revealed good-to-excellent owner satisfaction. Cranial cruciate ligament rupture, tibial deformities, and medial patellar luxation are difficult to treat together. A modified TTO may be used to treat these conditions.

Thoracolumbar partial lateral corpectomy for the treatment of chronic intervertebral disc disease in 107 dogs.

BACKGROUND: The purpose of this retrospective study was to assess short-and medium-term outcomes in dogs with chronic ventral thoracolumbar intervertebral disc disease (IVDD) treated by thoracolumbar partial lateral corpectomy (TLPLC). Dogs surgically treated for chronic ventral IVDD by TLPLC were included. For each dog, neurological status evolution and complications were reported. Factors that could have influenced neurological recovery were statistically tested. RESULTS: A total of 107 dogs were included in the study. Before surgery, 67.3 % of the dogs were able to walk, 24.3 % were grade 3, and 8.4 % were grade 4. The median hospitalization time was 3 days, and 82.2 % of the dogs were able to walk at discharge. The medium-term neurological grade was reached at a median time of 2 months. At the medium-term follow-up (median 12 months), 74.3 % of the dogs were neurologically improved, 22.9 % were stable, and 2.8 % were worsened. A total of 91.4 % of dogs were ambulatory, with 58.6 % of dogs having a normal gait. Preoperative neurological grade was significantly associated with the neurological status 24 h after the surgery and at discharge. Dogs with a higher preoperative neurological grade had a better chance of improving but lower odds of walking at 24 h after the surgery and at discharge compared with dogs with a lower preoperative grade. Spinal compression recurrence at the same surgical site was confirmed in 8 cases. CONCLUSION: Even if TLPLC leads to several intra and postoperative complications, this technique is a viable surgical option to treat chronic ventral IVDD.

Ultrastructural analysis of healthy synovial fluids in three mammalian species.

A better knowledge of synovial fluid (SF) ultrastructure is required to further understand normal joint lubrication and metabolism. The aim of the present study was to elucidate SF structural features in healthy joints from three mammalian species of different size compared with features in biomimetic SF. High-resolution structural analysis was performed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and environmental SEM/wet scanning transmission electron microscopy mode complemented by TEM and SEM cryogenic methods. Laser-scanning confocal microscopy (LCM) was used to locate the main components of SF with respect to its ultrastructural organization. The present study showed that the ultrastructure of healthy SF is built from a network of vesicles with a size range from 100 to a few hundred nanometers. A multilayered organization of the vesicle membranes was observed with a thickness of about 5 nm. LCM study of biological SF compared with synthetic SF showed that the microvesicles consist of a lipid-based membrane enveloping a glycoprotein gel. Thus, healthy SF has a discontinuous ultrastructure based on a complex network of microvesicles. This finding offers novel perspectives for the diagnosis and treatment of synovial joint diseases.

Retrospective study of the early clinical experience with a precontoured angle-stable interlocking nail for fracture repair in dogs and cats.

OBJECTIVE: To report indications, outcomes, and complications with a precontoured angle-stable interlocking nail (CAS-ILN). ANIMALS: 90 client-owned animals. METHODS: Dogs and cats treated with the CAS-ILN between 2020 and 2022 were retrospectively reviewed. Collected data included body weight, fracture configuration, percentage of medullary canal filled, limb alignment, complications, and follow-up. Favorable outcomes were defined when full functional restoration was observed. RESULTS: Thirty-eight dogs and 52 cats were included. Median body weight was 4.3 kg (range, 1.5 to 6.7 kg) for cats and 25 kg (range, 6.8 to 54 kg) for dogs. A total of 54 femurs, 31 tibias, and 5 humeri were treated, including 65 comminuted fractures and 26 metaphyseal fractures. The median percentage of medullary canal occupied by the nail was 76.5% (range, 53% to 97.6%). Radiographic postoperative bone alignment was good in 85.5% (59/69) and satisfactory in 10 cases. The median duration of follow-up (57/90) was 476 days (range, 56 to 1,057 days). In the perioperative period (0 to 12 weeks), lameness had resolved or was mild in all (51/52) but 1 case. In the long-term postoperative period (> 12 months), 97.1% (34/35) of cases showed restoration of full function and 1 case had an unacceptable function. An overall complication rate of 11.5% (7/61) was reported including 1 catastrophic and 6 major complications. CLINICAL RELEVANCE: Long-term functional outcomes following the CAS-ILN were favorable in 97.1% (34/35) of cases. Complication rates were comparable to previous studies. The CAS-ILN appears to be an alternative surgical option for most long-bone fracture repairs.

Shunting between the CVC and both the azygos vein and thoracic duct in a dog with CTD.

A 5 mo old female rottweiler was referred for evaluation of a suspected congenital heart disease. Clinical signs included anorexia, exercise intolerance, and severe loss of body condition. Clinical examination revealed dyspnea, pale mucous membranes, and weak femoral pulses. Pleural and abdominal effusions and iron deficiency anemia were identified. A distended intrathoracic caudal vena cava (CVC) visible on thoracic radiographs suggested that the modified transudate abdominal effusion was the result of improper venous return to the right side of the heart. Cor triatriatum dexter (CTD) was diagnosed via echocardiography but did not explain all the anomalies detected during a contrast echocardiography. Abnormal communications between the CVC and azygos vein and the CVC and thoracic duct were subsequently identified by abdominal ultrasonography and angiography. Medical management with diuretics, iron supplements, and surgical treatment of CTD resulted in normalization of the respiratory rate, the exercise intolerance, and the anemia. To the authors' knowledge, this is the first reported case of CTD associated with shunts between the CTV and both the azygos vein and thoracic duct in dogs. This report emphasizes the importance of presurgical assessment of concurrent thoracic and abdominal congenital vascular abnormalities.

Effect of the surface geometry of uncemented acetabular cups on primary stability in a model of uncemented total hip replacement in dogs.

OBJECTIVE: To compare the in vitro stability of acetabular cups with peripherally reinforced fixation in a model of uncemented total hip replacement in dogs. SAMPLE: 63 polyurethane foam blocks and 3 acetabular implant designs: hemiellipsoidal (Model A) and 2 models with equatorial peripheral fins (Model B with 1 level and Model C with 2 levels of fins). METHODS: 2 loading patterns-edge loading and push-out tests-were performed until failure and peak forces were recorded. Implantation behavior was visually assessed and the required seating force was assessed using a force-displacement curve. RESULTS: Model B showed significantly lower peak force than Model A in edge loading tests with standardized impaction. In the push-out test, Model A had a greater maximal force than Models B and C, with mean maximal forces of 213.7 N, 139.4 N, and 138.9 N, respectively. In the seating force test, Models B and C required a higher force for 2-mm deep implantation (362.0 N and 361.6 N, respectively) than Model A (194.4 N), and were associated with dorsal tilting of the components. CLINICAL RELEVANCE: Our results suggest that cups with a peripheral design (B, C) have less primary stability than hemiellipsoidal cups (A). Furthermore, models with peripheral fins (B, C) appeared to have incomplete seating if a higher force was not used during implantation and, therefore, the risk of malpositioning was increased. These data indicate that hemiellipsoidal cups provide the same or better initial stability and require a lower impaction force.

Treatment of Medial Shoulder Joint Instability by Stabilization with an Arthroscopically Guided Prosthetic Ligament: A Cadaveric Feasibility Study in Dogs.

OBJECTIVE: The aim of this study was to assess the feasibility and efficiency of an arthroscopically guided ligamentoplasty of the medial glenohumeral ligament to treat medial shoulder joint instability. STUDY DESIGN: Six Beagle cadavers were used (12 limbs). Both arms of the medial glenohumeral ligament were severed using arthroscopic guidance. Arthroscopically guided reconstruction of the ligament was performed. Threaded sutures were fixed with a bone anchor on the medial aspect of the glenoidal cavity of the scapula, passed through a humeral tunnel and finally tensioned with a suture button on lateral aspect of the humerus. Shoulder abduction angles were measured before and after the section of the medial glenohumeral ligament, and following the surgery. Two orthogonal radiographic projections and dissections were performed after each procedure to grade the placement of the implants. RESULTS: Surgical repairs were achieved in 10 out of 12 limbs. The abduction angles after repair with ligamentoplasty were not significantly different from the abduction angles measured before the section of the medial glenohumeral ligament. CONCLUSION: Arthroscopically guided ligamentoplasty with a scapular bone anchor and a humeral drilling tunnel is feasible in cadavers, and efficient to restore acutely shoulder abduction angle in a minimally invasive manner. Further clinical studies are required to assess in vivo results.

Use of Ultrasonography in Diagnosis of Medial Compartment Disease of the Elbow in Dogs.

OBJECTIVE: The objective of this prospective study was to evaluate the use of ultrasonography in the diagnosis of medial coronoid process disease in unclear cases. STUDY DESIGN: Fifteen elbows (on thirteen dogs) for which radiography and computed tomography did not lead to a clear diagnosis of medial coronoid process disease were included. On each elbow, ultrasonography was performed with a high frequency linear transducer (12-18Hz). Then, arthroscopic examination of the joint was performed by a surgeon who was unaware of ultrasonographic findings to confirm medial coronoid process disease. RESULTS: At least one ultrasonographic lesion was detected in 13 out of 15 elbows. The main reported ultrasonographic lesions were joint effusion (10/15 elbows) and an abnormal shape of the medial coronoid process (irregular, ill-defined or fragmented) (9/15). CONCLUSION: Ultrasonography can be a helpful additional diagnostic tool to confirm medial coronoid process disease of the elbow joint before performing arthroscopy in unclear cases. Further studies will be needed to evaluate the use of higher frequency transducers and determine if it could improve the diagnostic value of ultrasonography.

Intra-articular replacement of the caudal cruciate ligament using a UHMWPE ligament under arthroscopic guidance in a dog: A case report.

Background: As isolated ruptures of the caudal cruciate ligament (CdCL) are rare in dogs, there is no consensus on the indications and the gold-standard surgical technique for treatment. Case Description: A 2-year-old Shepherd dog with an isolated rupture of the CdCL was treated with a new surgical technique for synthetic reconstruction. Three bone tunnels were drilled in the femur and the tibia under arthroscopic guidance to make sure the anatomical insertions of the physiological ligament were respected. An ultra-high molecular weight polyethylene (UHMWPE) implant was fixed with interference screws to reconstruct the CdCL. A synovial inflammation remained present on radiographs for 6 months after the surgery, together with a mild lameness. However, the dog fully recovered clinically and recovered a normal level of activity after 6 months. Liverpool osteoarthritis in dogs questionnaire results at 6 months and 1 year postoperatively were excellent. Conclusion: The use of a UHMWPE implant fixed with interference screws to reconstruct the CdCL allowed a return to full function of the knee without complications, despite a persistent synovial inflammation and mild lameness for a 6-month period after the surgery. The success of this isolated surgical technique could lead to improvements in the surgical management of CdCL rupture, if these initial results are confirmed by a prospective study with a larger number of patients.

Ex-vivo biomechanical analysis of an original repair of canine calcaneal tendon rupture using a synthetic implant as mechanical support fixed by sutures in the proximal tendinous part and by an interference screw in the bone distal part.

Background: Rupture of the common calcaneal tendon is the second most frequent tendon rupture in dogs and may lead to severe lameness and pain. Surgical repair consists of re-apposition of the damaged tendon ends using sutures, but this type of repair is not always possible especially if the tendon has retracted. Tendon augmentation with an ultra-high molecular weight polyethylene (UHMWPE) implant is a recent solution to support the sutures and allow the repair of the canine calcaneal tendon. However, its biomechanical fixation strength remains untested for this pathology. Aim: To evaluate the biomechanical fixation strength of a UHMWPE implant for the repair of the canine calcaneal tendon. Methods: Ex-vivo biomechanical study was carried out on eight cadaveric hindlimbs from four adult dogs. Hindlimbs were tested under two independent modalities: proximal tendinous fixation (PTF) and distal calcaneus fixation (DCF), using a testing machine. PTF was achieved by eight simple interrupted polypropylene sutures performed through the UHMWPE implant. The latter was sandwiched inside the gastrocnemius tendon, which had previously been incised over about 5 cm longitudinally, and through the tendon of the superficial digital flexor. DCF was performed using an interference screw, which locked the UHMWPE implant into a calcaneus tunnel drilled perpendicularly. Results: Yield, failure load, and linear stiffness (mean ± SD) for the DCF modality were 920 ± 139 N, 1,007 ± 146 N, and 92 ± 15.21, respectively, which were greater than for the PTF modality (663 ± 92 N, 685 ± 84 N and 25.71 ± 5.74, respectively, p < 0.05). Failure modes were different between fixation modalities: for PTF it was suture breakage (n = 7/8), while for DCF it was implant damage and slippage (n = 8/8). Conclusion: The biomechanical fixation strength of the UHMWPE implant was greater for DCF than that of PTF, and should be suitable for calcaneal tendon repair in dogs. The clinical prediction of rupture of this calcaneal tendon repair will occur at the level of the PTF.

Validation of a biomechanical testing protocol of craniodorsal hip luxation in feline cadavers and comparison of two ultra-high molecular weight polyethylene materials used for extra-articular hip stabilisation.

OBJECTIVES: The aim of our study was to describe a biomechanical testing protocol to reproduce ex vivo craniodorsal hip luxation specific to the feline model, and evaluate the biomechanical properties of an intact hip joint compared with the fixation strength of two different techniques of extra-articular hip stabilisation. METHODS: Eighteen hip joints (femur and hemipelvis) were harvested from nine mature feline cadavers. CT was performed for each hip joint so that a biomechanical base specific to each joint morphotype could be created using computer-aided design. The biomechanical bases were then produced using a three-dimensional printer to secure the hip joints during testing. A total of 34 biomechanical compression tests were performed. Eighteen compression tests were performed in the control group, of which two fractured. The remaining 16 hip joints were then randomly assigned either to group A (hip joints stabilised with an extra-articular ultra-high molecular weight polyethylene (UHMWPE) implant secured by an interference screw [n = 8]) or to group B (hip joints stabilised with a UHMWPE iliofemoral suture [n = 8]). RESULTS: Mean ± SD yield, failure load and linear stiffness in the control group were 616 ± 168 N, 666 ± 158 N and 231 ± 50 N/mm, respectively. The relative fixation strength (% of intact joint) before hip luxation in groups A and B was 43.8% and 34.7%, respectively. No statistical difference was found between groups A and B for yield and failure load. However, the reoccurrence of craniodorsal hip luxation was higher in group B than in group A, in 5/8 and 0/8 tests, respectively. Moreover, in group A, the extra-articular UHMWPE implant induced caudodorsal hip luxation, reported as failure mode in 7/8 cases. CONCLUSIONS AND RELEVANCE: This modified biomechanical protocol for testing craniodorsal hip luxation in a feline model was validated as repeatable and with acceptable variance. The extra-articular UHMWPE implant stabilisation technique proved to be more efficient in avoiding reoccurrence of craniodorsal hip luxation than UHMWPE iliofemoral suture.

Transoral ventral tympanic bulla osteotomy in cats: 13 cases (2016-2019).

OBJECTIVE: To analyze the results of transoral ventral bulla osteotomy (TOVBO) in cats. ANIMALS: 13 client-owned cats treated by TOVBO between February 2016 and February 2019. PROCEDURES: Medical records of cats with a diagnosis of middle ear disease (MED) that underwent TOVBO were reviewed. The procedure was similar to the one described for dogs. Short-term follow-up was obtained via clinical examination before discharge and at day 15 postoperatively. Long-term follow-up was performed via telephone interview. RESULTS: 13 cats (age range, 8 months to 12 years) underwent unilateral (n = 10) or bilateral (3) TOVBO (16) for the treatment of tympanic bulla (TB) infection (10), nasopharyngeal inflammatory polyps (5), or bullet retrieval from the TB (1). There were no intraoperative complications. One cat with a poor preoperative status died at postoperative day 3 from pneumonia. Eight cats experienced postoperative complications including head tilt (n = 2), Horner syndrome (3), loss of appetite (2), and temporary blindness (1). Collected samples confirmed the presence of nasopharyngeal inflammatory polyps (5), or otitis media (8). Six months after surgical intervention, 9 cats were free of MED signs. CLINICAL RELEVANCE: This oral approach provided a good access to the TB in all cases. The complications observed after TOVBO were similar to those for VBO. In cats, TOVBO seems to be an acceptable and safe minimally invasive alternative to the other approaches of the TB to address MED.

Micromechanical properties of the healthy canine medial meniscus.

AIMS: Knowledge of the micromechanical characteristics of the menisci is required to better understand their role within the stifle joint, improve early diagnosis of meniscal lesions, and develop new treatment and/or replacement strategies. The aim of the study was to determine the mechanical properties of the healthy medial canine meniscus and to evaluate the effect of regional (caudal, central, and cranial) and circumference (axial and abaxial) locations on these properties. METHODS: To study the micromechanical properties of the medial menisci in healthy (Beagle) dogs, the influence of regional (caudal, central, and cranial) and circumference (axial and abaxial) locations were evaluated. Nanoindentation-relaxation tests were performed to characterize the local stiffness and the viscoelastic properties at each region and specific circumference. Linear interpolation onto the indentation points was performed to establish a map of the micromechanical property heterogeneities. RESULTS: The results indicate that the cranial region was significantly stiffer and less viscous than the central and caudal regions. Within the central region the inner part (axial) was significantly stiffer than the periphery (abaxial). Within the caudal region the inner part was significantly less viscous than the periphery. CONCLUSION: Significant regional and radial variations were observed for both the stiffness and the viscoelastic properties. Moreover, a viscous behavior of the entire medial meniscus was observed (elastic fraction <0.5). These results deter the use of average elastic modulus to study the regional mechanical properties of healthy meniscus.

A morphometric analysis of thoracolumbar vertebrae in goat by computed tomography.

The goat spine is widely used as an animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Therefore, precise morphometric data are needed. This study aims to provide morphometric data of the goat thoracolumbar vertebrae and to define the parameters/characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine in goat. Eleven 36-month-old adult alpine goats were included in this study, and a sample of 198 vertebrae was measured. Subsequently, transverse and sagittal images were obtained using a multi-detector-row helical computed tomography (CT) scanner. Measurements of the vertebral bodies (ventral body width VBW, ventral body depth VBD, ventral body height ventral VBHv, ventral body high dorsal VBHd, spinal canal depth SCD, spinal canal width SCW), pedicles (pedicle length PDL, pedicle width PDW, pedicle angle PA and pedicle axis length PAL), intervertebral disc (DT) and transverse process length (TPL) were performed with dedicated software. The vertebral bodies and the spinal canal were wider than deep, mostly evident in the lumbar region. The intervertebral discs were as much as 65.7% thicker in the lumbar spine than in the thoracic spine. The pedicles were longer than wide over the thoracic and lumbar spines. The insertion angles in pedicle were approximately 30° for the T2-T4 segment, 25° for the T5-T6 segment, 23° for the T6 to T11 segment, 20° for T11 to L3, 25° for L4 and 30° for L5 and L6. In conclusion, the generated data can serve as a CT reference for the caprine thoracolumbar spine and may be helpful in using the goat spine as an animal model for human spinal research.

Long-term outcome following synthetical reconstruction of the medial collateral tarsal ligament in a dog.

Background: Tibiotarsal instabilities caused by partial or complete rupture of the medial collateral tarsal ligament (MCTL) are commonly treated by arthrodesis techniques with poor functional results and significant complication rates. Case Description: This study describes a new surgical technique for synthetic reconstruction of the MCTL in an overweight dog (estimated body condition score 8/9) with an avulsion of the long head of the MCTL. Three bone tunnels were drilled in the distal tibia, the talus, and the central tarsal bone, thus respecting the anatomical insertions of the physiological ligament. An Ultra-High Molecular Weight Polyethylene (UHMWPE) implant was fixed with interference screws to reconstruct the long and short heads of the MCTL. Premature weight-bearing was reported at 2 weeks postoperatively following early removal of the flexible restraint (bivalve resin boot), which had initially been prescribed for 6 weeks. At 11 weeks postoperatively, the tibiotarsal joint showed good valgus stability and the dog's gait was subnormal. At 12 and 16 months postoperatively, the dog regained full function of the operated limb although no weight loss was initiated as recommended. Conclusion: The use of a UHMWPE implant fixed with interference screws to reconstruct the MCTL allowed a return to full function of the tibiotarsal joint, without complications despite an early return to weight-bearing without external restraint. The success of this isolated surgical technique could lead to improvements in the surgical management of MCTL rupture if these initial results are confirmed by a prospective study with a larger number of patients.

Biomechanical cyclic loading test of a synthetic ligament fixation system used for intra-articular stabilization of deficient canine stifles.

Background: Cranial cruciate ligament rupture (CCLr) is the most common cause of hind limb lameness in dogs. Currently, surgical management of CCLr is mostly performed using tibial osteotomy techniques to modify the biomechanical conformation of the affected stifle. These surgical techniques have a significant complication rate, associated with persistent instability of the stifle which may lead to chronic postoperative pain. Over the last decade, studies have been published on various techniques of anatomical caudal cruciate ligament reconstruction in veterinary practice, using physiological autografts or woven synthetic implants. Aim: The aim of this ex vivo biomechanical study is to investigate the ex vivo dynamic biomechanical behavior of a synthetic implant [ultrahigh molecular weight polyethylene (UHMWPE) implant] fixed with interference screws for the treatment of CCLr in dogs, according to a fatigue protocol (48 hours per test). Methods: Seven stifles from four skeletally mature canine cadavers were implanted with the synthetic implant. It was fixed with four interference screws inserted in transversal and oblique tunnels in both the distal femur and the proximal tibia. For each case, 100,000 cycles were performed at 0.58 Hz, with traction loads ranging from 100 to 210 N. Results: Neither screw-bone assembly rupture nor a pull-out issue was observed during the dynamic tests. Linear stiffness of the implants associated with a fixation system with four interference screws increased over time. The final displacement did not exceed 3 mm for five of the seven specimens. Five of the seven synthetic implants yielded to a lengthening in functional range (0-3 mm). Linear stiffness was homogeneous among samples, showing a strong dynamic strength of the interference screw-based fixations of the UHMWPE implant in the femoral and tibial bones. Conclusion: This study completes the existing literature on the biomechanical evaluation of passive stifle stabilization techniques with a testing protocol focused on cyclic loading at a given force level instead of driven by displacement. These biomechanical results should revive interest in intra-articular reconstruction after rupture of the CCLr in dogs.

Ex vivo postimplantation biomechanical properties of a press-fit cementless femoral stem with transfixation pin for canine total hip replacement.

OBJECTIVE: To compare ex vivo postimplantation biomechanical characteristics of 3 implants for canine total hip replacement: a cementless press-fit femoral stem with a pin in the femoral neck (p-pfFS), a press-fit cementless femoral stem without this pin (pfFS), and a cemented femoral stem (cFS). SAMPLE: 18 cadaveric femurs from 9 dogs. PROCEDURES: Femurs were assigned randomly to 3 groups, and biomechanical testing was performed by measuring vertical displacement during cyclic loading and resistance to failure with compression parallel to the longitudinal axis of the femur. Force-displacement curves were assessed for failure tests, and work necessary for failure was calculated. RESULTS: No significant differences were observed in vertical displacement during cyclic loading (P = .263) or work necessary for failure (P = .079). Loads to failure for cFS and p-pfFS implants were significantly greater than that for the pfFS, but no significant difference in load to failure was observed between cFS and p-pfFS implants (P = .48). CLINICAL RELEVANCE: Cementless femoral stems with a transfixation pin offer significantly greater immediate resistance to failure to compressive loads parallel to the longitudinal axis of the femur than standard cementless stems, and a level of stability comparable to that of cemented stems. p-pfFS implants may be valuable in total hip replacement, potentially reducing the risk of fracture during the early postoperative period prior to osteointegration.

Endoscope-assisted thoracolumbar lateral corpectomy.

OBJECTIVE: To report an endoscope-assisted lateral approach to expose the intervertebral foramen and disk and perform lateral corpectomy of thoracolumbar disks in dogs. STUDY DESIGN: Cadaver study. ANIMALS: Fresh canine cadavers (n=6). METHODS: A thoracic (T10-T11) and a lumbar (L3-L4) lateral approach were made on 6 fresh canine mixed breed cadavers. Through a limited skin incision, musculature was dissected and retracted using a neurosurgical self-retaining retractor and lateral corpectomy performed. The approach and bone removal, both performed under endoscopic control, were assessed. RESULTS: The foramen and intervertebral disk were clearly observed in all specimens without any iatrogenic injury of the ventral and dorsal nerve branches. Access to the foramen was possible in all specimens; in the thoracic area the head of the rib was always partially excised to observe the intervertebral disk medially. Lateral corpectomy was easily performed in all cadavers and spinal cord observation was good. Extension to foraminotomy or mini hemilaminectomy could easily be performed through the same limited approach. CONCLUSION: Endoscopic exploration provided a good viewing of the intervertebral disk and/or foramen. An endoscope-assisted thoracolumbar lateral corpectomy could effectively be performed through a limited approach to the thoracolumbar disks and allowed good ventral spinal cord assessment.