A retrospective multicenter study on the use of locking compression plates for scapulohumeral arthrodesis in small equids.

OBJECTIVE: To report on technical aspects and outcomes after scapulohumeral arthrodesis (SHA) with a locking compression plate (LCP) in small equids. STUDY DESIGN: Retrospective multicenter case series. ANIMALS: Client-owned Shetland Ponies, Miniature Shetlands, and American Miniature Horses (n = 15). METHODS: Inclusion criteria were completed SHA with an LCP to treat scapulohumeral osteoarthritis/subluxation and availability of postoperative radiographs. Contributing surgeons completed a questionnaire to collect data. All radiographs were reviewed for this study. Follow-up information was obtained via re-admission to the hospital or telephone interview of the referring veterinarian or owner. Outcome was subjectively scored as excellent, good, moderate, or poor based on lameness and function. RESULTS: Sixteen SHAs were performed in 15 equids (body weight 65-145 kg) by nine different surgeons. A narrow 4.5/5.0 mm LCP (7-16 holes) was used in 14 of the 16 SHAs. Follow-up was collected 2.5 years after surgery (median; range: 9 weeks to 10 years). Major complications related to the SHAs were noted in 4 of the 13 horses alive long term, consisting of implant failure (n = 1), surgical site infection (n = 2), and scapular fracture (n = 1). The outcome was graded as excellent in 4, good in 5, and moderate in 4 horses. Two ponies were euthanized because scapulohumeral osteoarthritis and subluxation developed in the contralateral limb. CONCLUSION: Although major complications occurred in about one-third of ponies, SHA with LCP led to long-term survival with good function in most ponies. CLINICAL SIGNIFICANCE: SHA with an LCP offers a high chance for good long-term outcome in small equids although contralateral disease may affect outcome.

Evaluation of four biodegradable, injectable bone cements in an experimental drill hole model in sheep.

Four cement applications were tested in this investigation. Two dicalcium phosphate dihydrate (DCPD-brushite) hydraulic cements, an apatite hydraulic fiber loaded cement, and a calcium sulfate cement (Plaster of Paris) were implanted in epiphyseal and metaphyseal cylindrical bone defects in sheep. The in vivo study was performed to assess the biocompatibility and bone remodeling of four cement formulations. After time periods of 2, 4, and 6 months, the cement samples were clinically and histologically evaluated. Histomorphometrically, the amount of new bone formation, fibrous tissue, and bone marrow and the area of remaining cement were measured. In all specimens, no signs of inflammation were detectable either macroscopically or microscopically. Cements differed mainly in their resorption time. Calcium sulfate was already completely resorbed at 2 months and showed a variable amount of new bone formation and/or fibrous tissue in the original drill hole over all time periods. The two DCPD cements in contrast were degraded to a large amount at 6 months, whereas the apatite was almost unchanged over all time periods.

The dynamisation of locking plate osteosynthesis by means of dynamic locking screws (DLS)-an experimental study in sheep.

In this in vivo study a new generation of locking screws was tested. The design of the dynamic locking screw (DLS) enables the dynamisation of the cortex underneath the plate (cis-cortex) and, therefore, allows almost parallel interfragmentary closure of the fracture gap. A 45° angle osteotomy was performed unilaterally on the tibia of 37 sheep. Groups of 12 sheep were formed and in each group a different osteotomy gap (0, 1 and 3mm) was fixed using a locking compression plate (LCP) in combination with the DLS. The healing process was monitored radiographically every 3 weeks for 6, respectively 12 weeks. After this time the sheep were sacrificed, the bones harvested and the implants removed. The isolated bones were evaluated in the micro-computed tomography unit, tested biomechanically and evaluated histologically. The best results of interfragmentary movement (IFM) were shown in the 0mm configuration. The bones of this group demonstrated histomorphometrically the most distinct callus formation on the cis-cortex and the highest torsional stiffness relative to the untreated limb at 12 weeks after surgery. This animal study showed that IFM stimulated the synthesis of new bone matrix, especially underneath the plate and thus, could solve a current limitation in normal human bone healing. The DLS will be a valuable addition to the locking screw technology and improve fracture healing.

The influence of different osteosynthesis configurations with locking compression plates (LCP) on stability and fracture healing after an oblique 45° angle osteotomy.

BACKGROUND: Locking compression plates are used in various configurations with lack of detailed information on consequent bone healing. STUDY DESIGN: In this in vivo study in sheep 5 different applications of locking compression plate (LCP) were tested using a 45° oblique osteotomy simulating simple fracture pattern. 60 Swiss Alpine sheep where assigned to 5 different groups with 12 sheep each (Group 1: interfragmentary lag screw and an LCP fixed with standard cortex screws as neutralisation plate; Group 2: interfragmentary lag screw and LCP with locking head screws; Group 3: compression plate technique (hybrid construct); Group 4: internal fixator without fracture gap; Group 5: internal fixator with 3mm gap at the osteotomy site). One half of each group (6 sheep) was monitored for 6 weeks, and the other half (6 sheep) where followed for 12 weeks. METHODS: X-rays at 3, 6, 9 and 12 weeks were performed to monitor the healing process. After sacrifice operated tibiae were tested biomechanically for nondestructive torsion and compared to the tibia of the healthy opposite side. After testing specimens were processed for microradiography, histology, histomorphometry and assessment of calcium deposition by fluorescence microscopy. RESULTS: In all groups bone healing occurred without complications. Stiffness in biomechanical testing showed a tendency for higher values in G2 but results were not statistically significant. Values for G5 were significantly lower after 6 weeks, but after 12 weeks values had improved to comparable results. For all groups, except G3, stiffness values improved between 6 and 12 weeks. Histomorphometrical data demonstrate endosteal callus to be more marked in G2 at 6 weeks. DISCUSSION AND CONCLUSION: All five configurations resulted in undisturbed bone healing and are considered safe for clinical application.

The European College of Veterinary Surgeons 1991-2011: a 20-year success story.

The first meeting leading to the formation of the European College of Veterinary Surgeons (ECVS) was held August 30/31, 1990 in Lenzburg, Switzerland. Specialists in small animal and large animal surgery from practice and academicians from many European countries were invited. The constitution was developed based on that of the American College of Veterinary Surgeons (ACVS). ECVS was founded during the ACVS European Surgical Forum in Nice in 1991. The provisional Board elected at this meeting stayed active during the initial 4 years to provide stability. For the 146 Charter Members to become a Diplomate, they had to pass an examination. Therefore, the ECVS is the only Specialty College that does not have a "Grand Father Clause." In 2000 ECVS, was the first College to acquire full recognition-status by the European Board of Specialization (EBVS), which underlines the leading role the surgeons play in the development of the European veterinary specialty colleges. Like its American Sister College, ECVS maintains high standards for surgical training programs for Residents and administers rigorous certifying examinations. It is appropriate to recall the facts that lead to foundation of ECVS on its 20-year anniversary.

Locking compression plate osteosynthesis of sacral fractures in three heifers.

OBJECTIVE: To describe a technique used for reduction and internal fixation of sacral fractures in cattle. STUDY DESIGN: Case series. ANIMALS: Three heifers aged 19-32 months with deformation of the tail head and tail paralysis attributable to a closed fracture of S5 or S4 and S5. METHODS: Fractures were reduced and repaired under general anesthesia. A narrow, 6-10-hole, locking compression plate (LCP) was placed on the spinous processes of S5 and the first coccygeal (Co1) using 5.0 mm locking head screws. Follow-up inquiries were made by telephone (3/3), and cows were examined clinically and radiographically 2 (1 cow) to 9 (1 cow) months postoperatively. RESULTS: No complications were encountered. The range of movement of the tail improved so that soiling of the tail during defecation was no longer a problem. In all heifers, the normal top line was restored and there was no narrowing of the pelvic canal. Unassisted calving occurred in all heifers, and follow-up radiographs for 2 cows showed complete fracture healing. CONCLUSION: LCP-osteosynthesis of the spinous processes provided sufficient stability for internal fixation of sacral fractures. Marked improvement in tail function occurred postoperatively without decompression by laminectomy.

Isolation, establishment, and characterization of ex vivo equine melanoma cell cultures.

Gray horses spontaneously develop metastatic melanomas that resemble human disease, and this is often accompanied with metastasis to other organs. Unlike in other species, the establishment of primary equine melanoma cultures that could be used to develop new therapeutic approaches has remained a major challenge. The purpose of the study was to develop a protocol for routine isolation and cultivation of primary equine melanocytes. Melanoma tissues were excised from 13 horses under local anesthesia, mainly from the perianal area. The melanoma cells were isolated from the melanoma tissue by serial enzymatic digestion using dispase and collagenase. Out of the 13 excised melanomas, cell cultures from eight melanomas were established, which corresponded to a success rate 62%. These cells showed different degrees of melanin pigmentation. Characterization of these cells using confocal microscopy, FACs analysis and western blotting showed that they expressed melanoma-associated antigens; Melan-A, MAGE-1, and MAGE-3, and PCNA expression was higher in fast-proliferating isolates. The protocol we developed and established proved successful for routine isolation and cultivation of primary equine melanoma cells. This method provided a large number of primary equine melanoma cells that could be used to study new therapeutic approaches for treatment of equine melanomas.

Short incomplete sagittal fractures of the proximal phalanx in ten horses not used for racing.

OBJECTIVE: To describe short incomplete sagittal fractures of the proximal phalanx (type Ia P1 fractures) in horses not used for racing and report outcome. STUDY DESIGN: Retrospective study. ANIMALS: Horses (n=10) with type Ia P1 fractures. METHODS: Retrieved data of horses with type Ia P1 fractures were signalment, history and results of orthopedic examination. Radiographs were re-evaluated for position and length of the fracture line, presence of osteoarthritis or subchondral cystic lesions (SCL), periosteal new bone formation and subchondral sclerosis. Conservative treatment (n=4) included box confinement for 2 months followed by 1 month of hand walking. Surgical therapy (n=6) consisted of internal fixation by screws inserted in lag fashion in 5 horses. Concurrent SCL were debrided by curettage via a transcortical drilling approach. In 1 horse, only SCL curettage but not internal fixation was performed. Outcome was assessed on a clinical and radiographic follow-up examination in all horses. RESULTS: Mean follow-up time was 27 months (median, 13.5 months; range, 9 months to 9 years). All horses treated with internal fixation were sound at follow-up and had radiographic fracture healing. Of the 4 horses managed conservatively, 3 remained lame and only 1 horse had radiographic evidence of fracture healing. Catastrophic fracture propagation occurred in 2 horses not treated by internal fixation, 20 and 30 months after diagnosis, respectively. CONCLUSIONS: Horses with a type Ia P1 fracture treated surgically had a better outcome than those managed conservatively and lack of fracture healing seemingly increases the risk of later catastrophic fracture. CLINICAL RELEVANCE: Surgical repair of type Ia P1 fractures should be considered to optimize healing and return to athletic use.

Refining animal models in fracture research: seeking consensus in optimising both animal welfare and scientific validity for appropriate biomedical use.

BACKGROUND: In an attempt to establish some consensus on the proper use and design of experimental animal models in musculoskeletal research, AOVET (the veterinary specialty group of the AO Foundation) in concert with the AO Research Institute (ARI), and the European Academy for the Study of Scientific and Technological Advance, convened a group of musculoskeletal researchers, veterinarians, legal experts, and ethicists to discuss, in a frank and open forum, the use of animals in musculoskeletal research. METHODS: The group narrowed the field to fracture research. The consensus opinion resulting from this workshop can be summarized as follows: RESULTS & CONCLUSION: Anaesthesia and pain management protocols for research animals should follow standard protocols applied in clinical work for the species involved. This will improve morbidity and mortality outcomes. A database should be established to facilitate selection of anaesthesia and pain management protocols for specific experimental surgical procedures and adopted as an International Standard (IS) according to animal species selected. A list of 10 golden rules and requirements for conduction of animal experiments in musculoskeletal research was drawn up comprising 1) Intelligent study designs to receive appropriate answers; 2) Minimal complication rates (5 to max. 10%); 3) Defined end-points for both welfare and scientific outputs analogous to quality assessment (QA) audit of protocols in GLP studies; 4) Sufficient details for materials and methods applied; 5) Potentially confounding variables (genetic background, seasonal, hormonal, size, histological, and biomechanical differences); 6) Post-operative management with emphasis on analgesia and follow-up examinations; 7) Study protocols to satisfy criteria established for a "justified animal study"; 8) Surgical expertise to conduct surgery on animals; 9) Pilot studies as a critical part of model validation and powering of the definitive study design; 10) Criteria for funding agencies to include requirements related to animal experiments as part of the overall scientific proposal review protocols. Such agencies are also encouraged to seriously consider and adopt the recommendations described here when awarding funds for specific projects. Specific new requirements and mandates related both to improving the welfare and scientific rigour of animal-based research models are urgently needed as part of international harmonization of standards.

Compensatory load redistribution of horses with induced weight-bearing forelimb lameness trotting on a treadmill.

The study was performed to obtain a detailed insight into the load and time shifting mechanisms of horses with unilateral weight-bearing forelimb lameness. Reversible lameness was induced in 11 clinically sound horses by applying a solar pressure model. Three degrees of lameness (subtle, mild and moderate) were induced and compared with sound control measurements. Vertical ground reaction force-time histories of all four limbs were recorded simultaneously on an instrumented treadmill. Four compensatory mechanisms could be identified that served to reduce structural stress, i.e. peak vertical force on the affected limb: (1) with increasing lameness, horses reduced the total vertical impulse per stride; (2) the diagonal impulse decreased selectively in the lame diagonal; (3) the impulse was shifted within the lame diagonal to the hindlimb and in the sound diagonal to the forelimb; (4) the rate of loading and the peak forces were reduced by prolonging the stance duration. Except in the diagonal hindlimb, where peak vertical forces increased slightly in the moderate lameness condition, no equivalent compensatory overload situation was observed in the other limbs. Specific force and time information of all four limbs allow the unequivocal identification of the affected limb.

The effect of cartilage and bone density of mushroom-shaped, photooxidized, osteochondral transplants: an experimental study on graft performance in sheep using transplants originating from different species.

BACKGROUND: Differences in overall performance of osteochondral photooxidized grafts were studied in accordance of their species origin and a new, more rigorous cleansing procedure using alcohol during preparation. METHODS: Photooxidized mushroom-shaped grafts of bovine, ovine, human and equine origin were implanted in the femoral condyles of 32 sheep (condyles: n = 64). No viable chondrocytes were present at the time of implantation. Grafts were evaluated at 6 months using plastic embedded sections of non-decalcified bone and cartilage specimens. Graft incorporation, the formation of cyst-like lesions at the base of the cartilage junction as well as cartilage morphology was studied qualitatively, semi-quantitatively using a score system and quantitatively by performing histomorphometrical measurements of percentage of bone and fibrous tissue of the original defects. For statistical analysis a factorial analysis of variance (ANOVA- test) was applied. RESULTS: Differences of graft performance were found according to species origin and cleansing process during graft preparation. According to the score system cartilage surface integrity was best for equine grafts, as well as dislocation or mechanical stability. The equine grafts showed the highest percentage for bone and lowest for fibrous tissue, resp. cystic lesions. The new, more rigorous cleansing process decreased cartilage persistence and overall graft performance. CONCLUSION: Performance of grafts from equine origin was better compared to bovine, ovine and human grafts. The exact reason for this difference was not proven in the current study, but could be related to differences in density of cartilage and subchondral bone between species.

Vertical ground reaction force-time histories of sound Warmblood horses trotting on a treadmill.

The objective of this study was to establish representative treadmill ground reaction force (GRF) and interlimb co-ordination time data of clinically sound horses at the trot. It was anticipated that these normative standards would provide a reference data base against which lame horses could be compared. GRF-time histories were collected from 30 Warmblood riding horses with easy, wide natural gaits. Data were recorded of all four limbs simultaneously by the use of an instrumented treadmill. A total of 912 stride cycles per limb were analysed for force, time and spatial parameters and were averaged. The shape and amplitude of the treadmill force curves were very similar to force traces recorded with a stationary force plate. The horses showed a high degree of symmetry in all investigated parameters (95% reference interval of left-right asymmetry +/-1.8-6.8%). No significant differences were found between left and right mean values. Intra-individual coefficients of variance of the various parameters did not exceed 2.7%. Inter-individual coefficients of variance were 2.5-3.5 times larger than the respective intra-individual coefficients. An instrumented treadmill provides a number of decisive advantages, such as time-efficient data acquisition of all four feet simultaneously over successive strides, or the high regularity of the horse's gait pattern at controlled velocities, which allow the clinical assessment of locomotor performance of horses.

Localized insulin-like growth factor I delivery to enhance new bone formation.

Insulin-like growth factor I (IGF I) exerts an important role during skeletal growth and bone formation. Therefore, its localized delivery appears attractive for the treatment of bone defects. To prolong IGF I delivery, we entrapped the protein into biodegradable poly(lactide-co-glycolide) microspheres (PLGA MS) and evaluated the potential of this delivery system for new bone formation in two defect models of ovine long bones, i.e., a 8-mm methaphyseal drill hole and a 10-mm segmental tibia defect. Administration of 100 microg of IGF I in PLGA MS resulted in new bone formation within 3 weeks in the drill hole and bridging of the segmental defect within 8 weeks. The observed increase of 12% newly formed bone in the drill hole defect after 3 weeks was substantial, compared to the measured morphometric bone-to-total area ratio of 31% bone in normal cancellous bone. Bone regeneration was further explored by measuring gene expression of typical markers for local mediators and growth factors by real-time polymerase chain reaction. Inflammation was reduced in presence of IGF I and this in vivo observation was corroborated in vitro by quantifying gene expression of inflammatory proteins and by assessing the activation of the NF-kappaB pathway, playing an important role in the regulation of inflammation. Administration of the IGF I delivery system downregulated inflammatory marker gene expression at the site of bone injury, induced new bone formation and reduced bone resorption, and resulted in bridging of 10-mm segmental tibial defects within 8 weeks.

Scapulohumeral arthrodesis in miniature horses.

OBJECTIVES: To describe surgical arthrodesis of the scapulohumeral joint and to evaluate its efficacy in reducing morbidity associated with severe shoulder dysfunction in miniature horses. STUDY DESIGN: Retrospective study. ANIMALS: Four miniature horses. METHODS: Medical records and radiographs were reviewed for history, physical examination findings, lameness evaluation, radiographic evaluation, surgical techniques, postoperative complications, and outcome. A 10- or 11-hole, 4.5-mm narrow dynamic compression plate and 4.5-mm cortical screws were applied to the cranial surface of the scapula and cranial surface of the humerus after osteotomy of the intermediate tubercle. In most horses, 1 or 2 screws were inserted in lag fashion across the joint, through holes in the plate. RESULTS: Scapulohumeral osteoarthritis was diagnosed radiographically in 4 horses, and 3 horses had concurrent shoulder luxation or subluxation. All horses had grade 3 or 4 lameness before surgery, and most improved by 1 to 2 grades after surgery. Despite complications of implant failure (2 horses), infection (2 horses), scapular fracture (1 horse), and atrophy of the shoulder muscles (1 horse), functional arthrodesis reduced morbidity in all horses. CONCLUSIONS: Scapulohumeral arthrodesis facilitates early return to weight bearing in miniature horses with severe scapulohumeral joint osteoarthrosis. Despite functional gait abnormality, the horses ambulated quite well after surgery. CLINICAL RELEVANCE: Scapulohumeral arthrodesis should be considered for debilitating conditions of the shoulder joint in miniature horses, especially when the intended outcome is breeding or pasture soundness.

Comparison of double dynamic compression plating versus two configurations of an internal veterinary fixation device: Results of in vitro mechanical testing using a bone substitute.

OBJECTIVE: To compare the mechanical properties of 2 configurations of a veterinary fixation system (VFS) for large animal long bones with dynamic compression plating (DCP). SAMPLE POPULATION: Eighteen pairs of Canevasit tubes (Canevasit; Amsler und Frei, Schinznach Dorf, Switzerland) (length, 170 mm; diameter, 47.5 mm; cortex thickness, 10 mm), aligned with a 10-mm gap, and stabilized with 2 DCP or 2 VFS implants. METHODS: Three groups (n = 6) were compared. Group 1 Canevasit tubes were stabilized with two 10-hole, broad 4.5-mm stainless steel DCP applied with both plates centered over the gap, in orthogonal planes parallel to the long axis of the tubes and staggered to allow bicortical fixation with ten 4.5-mm, 52-mm-long cortex screws each. Group 2 tubes were stabilized similarly with 2 VFS implants, each composed of a stainless steel rod (length, 167 mm; diameter, 8 mm), and 10 clamps were applied in alternating fashion left and right on the rod and fixed bicortically with ten 4.5-mm, 52-mm-long, cortex screws. Group 3 tubes were stabilized similarly, but using only 6 clamps/rod. All groups were tested initially in torsion within elastic limits and subsequently in 4-point bending, with 1 implant on the tension side, until gap closure occurred. RESULTS: None of the constructs failed, but all had plastic deformation after 4-point bending. No statistically significant differences were found among the 3 groups in torsional stiffness. Double DCP fixation was significantly stiffer and stronger in 4-point bending, compared with both configurations of double VFS fixation. CONCLUSIONS: The plate design was favored in this study. The VFS system may have to be adapted before further tests are conducted. Test modalities have to be chosen closer to clinical conditions (real bone, cyclic loading, closed gap). CLINICAL RELEVANCE: The veterinary fixation system has not yet proven its advantages for large animal long bone fracture repair. From the pure mechanical point of view, double DCP is the favored method for the treatment mentioned.

Instrumented treadmill for measuring vertical ground reaction forces in horses.

OBJECTIVE: To develop and validate a novel instrumented treadmill capable of determining vertical ground reaction forces of all 4 limbs simultaneously in horses. SAMPLE POPULATION: Data obtained while a horse was walking and trotting on the treadmill. PROCEDURE: 18 piezo-electric force transducers were mounted between the treadmill frame and supporting steel platform to measure the actual forces at the corresponding bearing points. Each of the 18 sensor forces is equal to the sum of the unknown hoof forces weighted with the transfer coefficients of the corresponding force application points. The 4 force traces were calculated, solving at each time point the resulting equation system, using the Gaussian least-squares method. System validation comprised the following tests: determination of the survey accuracy of the positioning system, determination of the natural frequencies of the system, linearity test of the force transfer to the individual sensors, determination of superimposed forces with the treadmill-integrated force measuring system (TiF) in a static configuration, and comparison of vertical ground reaction forces determined simultaneously by use of TiF and force shoes mounted on the forelimbs of a horse. RESULTS: Comparison between static test loads and TiF-calculated forces revealed deviations of < 1.4%. Force traces of TiF-calculated values and those recorded by use of the force shoes were highly correlated (r > or = 0.998). CONCLUSIONS AND CLINICAL RELEVANCE: This instrumented treadmill allows a reliable assessment of load distribution and interlimb coordination in a short period and, therefore, is suitable for use in experimental and clinical investigations.