Christoph Lischer

An in vitro biomechanical comparison of a locking compression plate fixation and kerf cut cylinder fixation for ventral arthrodesis of the fourth and the fifth equine cervical vertebrae

OBJECTIVESnTo (1) define mechanical properties in flexion, extension, and left lateral bending of cadaveric equine 4th and 5th cervical (C4-C5) articulations, (2) compare biomechanical properties of C4-C5 when stabilized with a kerf cut cylinder (KCC) compared with a ventrally placed 4.5 mm locking compression plate (LCP).nnnSTUDY DESIGNnIn vitro biomechanical investigation.nnnSAMPLE POPULATIONnCadaveric adult equine cervical vertebral columns (n=54).nnnMETHODSnCervical vertebrae aged by horse dentition and size measured from radiographs were divided into 3 age groups then randomly allocated to 3 groups. The C4-C5 articulation was treated differently in each of the groups: KCC group; KCC-implanted LCP group; 8-hole 4.5 mm LCP implanted and intact group; no implant. Specimens were randomly subdivided into 1 of 3 loading conditions, before testing to failure under 4-point bending. Stiffness, yield bending moment, failure bending moment, and failure mode were recorded. General linear models were performed to analyze associations between biomechanical properties and test variables.nnnRESULTSnAll specimens failed at the C4-C5 intervertebral articulation. The cervical vertebrae with the LCP construct had significantly higher stiffness, yield bending moment, and failure bending moment than the KCC-implanted cervical vertebrae. Failure modes differed between groups and varied with loading direction: KCC group, fractures of C5 associated with the KCC were common; LCP group, screw pull out or fractures (of C4 and C5 bodies, during extension and the caudal aspect of C4 during left lateral bending) were common; and intact group, subluxations were most common.nnnCONCLUSIONSnIn this model, LCP constructs had superior biomechanical properties compared with KCC constructs. Further research investigating the effect of repetitive loading is indicated.

Effect of sedation on fore- and hindlimb lameness evaluation using body-mounted inertial sensors

REASONS FOR PERFORMING STUDYnDiagnostic analgesia is an integral part of equine lameness examinations, but is challenging to perform in uncooperative horses. Using sedation to facilitate this might, because of analgesic and ataxia-inducing effects, interfere with lameness evaluation.nnnOBJECTIVESnTo evaluate whether sedation with low-dose xylazine would alter lameness amplitude as measured by body-mounted inertial sensors.nnnSTUDY DESIGNnControlled experiment.nnnMETHODSnForty-four horses were randomly split into 2 groups. Lameness was measured using body-mounted inertial sensors before and after injection of xylazine (0.3xa0mg/kg bwt) or saline. Sedation was measured at 5, 20 and 60xa0min following treatment, and lameness evaluations were performed before (Time 0) and at 20 and 60xa0min after treatment. Forelimb lameness was determined by measuring the vector sum of mean head height maximum and minimum differences between all right and left forelimb strides (n>25) collected with the horse trotting in a straight line. Hindlimb lameness amplitude was determined by measuring mean pelvic height maximum and minimum differences between right and left hindlimb strides. Numbers of horses staying the same, improving or worsening were compared between groups at each time interval.nnnRESULTSnThere were no significant differences in head or pelvic movement asymmetry between xylazine and saline treatment groups. However, a few horses with forelimb lameness in the xylazine treatment group showed a large decrease in head movement asymmetry (decrease in forelimb lameness) at 60xa0min following sedation.nnnCONCLUSIONSnLow-dose sedation with xylazine may be used without the concern of potential lameness-masking effects for hindlimb lameness evaluation, but caution should be used in some horses with forelimb lameness of mild severity. The Summary is available in German - see Supporting information.

Comparison of healing in forelimb and hindlimb surgically induced core lesions of the equine superficial digital flexor tendon

OBJECTIVEnEven though equine multi-limb tendinopathy models have been reported, it is unknown if fore- and hindlimb tendon healing behave similarly. The aim of this study was to compare the healing process of surgically induced superficial digital flexor tendon (SDFT) core lesions of fore- and hindlimbs in horses.nnnMETHODSnTendon core lesions were surgically induced in the SDFT of both fore- and hindlimbs in eight horses. One randomly assigned forelimb and one randomly assigned hindlimb were injected with saline one and two weeks post-surgery. The healing process was monitored clinically and ultrasonographically. After 24 weeks, the tendons were harvested and biochemical, biomechanical and histological parameters were evaluated.nnnRESULTSnTwenty-four weeks post-surgery, the forelimb SDFT lesions had a significantly higher colour Doppler ultrasound vascularization score (p = 0.02) and glycosaminoglycan concentration (p = 0.04) and a significantly lower hydroxylysylpyridinoline content (p = 0.03).nnnCLINICAL RELEVANCEnOur results indicate that fore- and hindlimb SDFT surgically induced lesions exhibit significant differences in several important parameters of tendon healing 24 weeks post-surgery. These differences create significant challenges in using all four limbs and accurately interpreting the results that one might generate. Therefore these findings do not support the use of four-limb models for study of tendon injury until the reasons for these differences are much better understood.

Mandibular corrective osteotomy using novel locking compression plate 3.5/4.5/5.0 mm metaphyseal plates

OBJECTIVEnTo describe a technique and the outcome of using 3.5/4.5/5.0 Metaphyseal Locking Compression Plate for corrective osteotomy of mandibular brachygnathia.nnnSTUDY DESIGNnClinical report.nnnANIMALnEight-month Thoroughbred horse.nnnMETHODSnSevere mandibular brachygnathia was surgically treated by corrective osteotomy and fixation with 2 LCP 3.5/4.5/5.0 Metaphyseal plates inserted using minimally invasive technique.nnnRESULTSnSevere mandibular brachygnathia was treated successfully with minor complications and stable fixation after 3 months. Cosmetic outcome and owner satisfaction was excellent.nnnCONCLUSIONSnCorrective osteotomy and fixation with LCP 3.5/4.5/5.0 Metaphyseal plates can be considered as a surgical technique for correction of severe mandibular brachygnathia in weanlings.

Evaluation of Two Protocols Using Autologous Conditioned Serum for Intra-articular Therapy of Equine Osteoarthritis—A Pilot Study Monitoring Cytokines and Cartilage-Specific Biomarkers

Abstract We hypothesised that shorter treatment intervals of intraarticular autologous conditioned serum (ACS) injections would more beneficially affect the synovial fluid (SF) concentrations of IL‐1ra, IL‐1&bgr; and cartilage biomarkers, compared with the traditional weekly treatment intervals in joints suffering from natural OA. In a randomised comparative study, 12 horses with OA were allocated to two groups (n = 6). The horses in group 1 received three intraarticular ACS injections at weekly intervals, whereas the horses in group 2 received three intraarticular ACS injections at two‐day intervals. The levels of IL‐1ra, IL‐1&bgr;, CPII, C12C and CS 846 were determined in SF before and after ACS treatment using commercially available ELISA kits. The SF IL‐1ra concentration 1 hour and 4 hours after ACS injection was significantly increased compared to baseline levels and decreased back to it within 48 hours. Comparing the SF IL‐1ra, IL‐1&bgr;, C12C, CS 846 and CP II levels before and 42 days after ACS treatment, group 2 showed a significant decrease in all parameters and an approximation on the levels in normal joints. These results indicate that the long‐time effect of an ACS treatment given at two‐day intervals is characterized by decreased SF IL1ra, IL‐1&bgr;, C12C, CP II and CS 846 concentrations, which might indicate an improvement in joint inflammation and cartilage degrading processes. Further investigations with greater sample sizes have to prove if the two‐day treatment interval is preferable to the widely used treatment protocol of weekly intraarticular ACS injections. HighlightsSF IL‐1ra increased 1 hour and 4 hours after ACS injection.SF IL‐1ra decreased back to baseline levels within 48 hours after ACS injection.SF IL‐1ra after ACS injection was positively correlated with IL‐1ra in the ACS.All SF parameters approximated on levels in normal joints after a two‐day ACS treatment interval.

Radiographic measurements of the hooves of normal ponies

Knowledge of the normal radiographic anatomy of the equine foot and the relationship between the distal phalanx and the hoof capsule is imperative for objective assessment of hoof health. Little information is available for the hooves of ponies. The aim of this study was to establish a database of reference values for normal ponies and to investigate the relationship between the height at the withers and radiographic measurements of the hooves. Radiographic examinations were performed on 81 ponies, ranging from 81.5 to 148.0 cm height at the withers, immediately after foot trimming. Eighteen parameters were measured in the lateromedial view (front and hind feet) and 13 parameters were measured in the dorsopalmar view (front feet). Most linear measurements had a strong positive correlation with the height at the withers. The influence of height on angular measurements was weak. A linear regression model was adopted to enable calculation of reference values for a defined height at the withers. Left feet were longer in 72% of front feet and 67% of hind feet. The medial part of the hoof was more upright generally, but the medial hoof wall was shorter only in the right front feet. The front feet tended to be more upright than the hind feet. Compared to height at the withers, the hooves of ponies were relatively larger than the hooves of adult Warmblood horses investigated in a comparable study. The present study provides a database for farriers and veterinarians for hoof conformation, on the basis of which hoof preparation and an accurate diagnosis of lameness can be made.

Long term outcome after surgical correction of mandibular brachygnathia with unilateral type 1 external skeletal fixation

OBJECTIVEnTo describe complications and long-term outcome after surgical correction of severe overbite in 7 horses using corrective osteotomy and a Type I external fixator.nnnSTUDY DESIGNnCase series.nnnANIMALSnHorses (nu2009=u20097).nnnMETHODSnSeven horses with severe mandibular brachygnathia were treated by corrective osteotomy and a Type I external fixator. Data on surgical technique, complications, long-term outcome and owner satisfaction were recorded.nnnRESULTSnSevere mandibular brachygnathia was corrected successfully in all horses. Short term follow-up revealed a relatively high morbidity due to several complications such as surgical site infection, sequestrum formation and instability due to early pin loosening. Long-term over all owner satisfaction was very high.nnnCONCLUSIONSnCorrective osteotomy and fixation with an external fixator is an effective surgical technique for correction of severe mandibular brachygnathia and offers good results in a long-term perspective.Objective n nTo describe complications and long-term outcome after surgical correction of severe overbite in 7 horses using corrective osteotomy and a Type I external fixator. n n n nStudy Design n nCase series. n n n nAnimals n nHorses (nu2009=u20097). n n n nMethods n nSeven horses with severe mandibular brachygnathia were treated by corrective osteotomy and a Type I external fixator. Data on surgical technique, complications, long-term outcome and owner satisfaction were recorded. n n n nResults n nSevere mandibular brachygnathia was corrected successfully in all horses. Short term follow-up revealed a relatively high morbidity due to several complications such as surgical site infection, sequestrum formation and instability due to early pin loosening. Long-term over all owner satisfaction was very high. n n n nConclusions n nCorrective osteotomy and fixation with an external fixator is an effective surgical technique for correction of severe mandibular brachygnathia and offers good results in a long-term perspective.

Semi‐quantitative methods yield greater inter‐ and intraobserver agreement than subjective methods for interpreting 99mtechnetium‐hydroxymethylene‐diphosphonate uptake in equine thoracic processi spinosi

Scintigraphy is a standard diagnostic method for evaluating horses with back pain due to suspected thoracic processus spinosus pathology. Lesion detection is based on subjective or semi-quantitative assessments of increased uptake. This retrospective, analytical study is aimed to compare semi-quantitative and subjective methods in the evaluation of scintigraphic images of the processi spinosi in the equine thoracic spine. Scintigraphic images of 20 Warmblood horses, presented for assessment of orthopedic conditions between 2014 and 2016, were included in the study. Randomized, blinded image evaluation was performed by 11 veterinarians using subjective and semi-quantitative methods. Subjective grading was performed for the analysis of red-green-blue and grayscale scintigraphic images, which were presented in full-size or as masked images. For the semi-quantitative assessment, observers placed regions of interest over each processus spinosus. The uptake ratio of each processus spinosus in comparison to a reference region of interest was determined. Subsequently, a modified semi-quantitative calculation was developed whereby only the highest counts-per-pixel for a specified number of pixels was processed. Inter- and intraobserver agreement was calculated using intraclass correlation coefficients. Inter- and intraobserver intraclass correlation coefficients were 41.65% and 71.39%, respectively, for the subjective image assessment. Additionally, a correlation between intraobserver agreement, experience, and grayscale images was identified. The inter- and intraobserver agreement was significantly increased when using semi-quantitative analysis (97.35% and 98.36%, respectively) or the modified semi-quantitative calculation (98.61% and 98.82%, respectively). The proposed modified semi-quantitative technique showed a higher inter- and intraobserver agreement when compared to other methods, which makes it a useful tool for the analysis of scintigraphic images. The association of the findings from this study with clinical and radiological examinations requires further investigation.

Objective Evaluation of the Response to Perineural Analgesia of the Deep Branch of the Lateral Plantar Nerve and Intraarticular Analgesia of the Tarsometatarsal Joint in Horses With Suspected Proximal Metatarsal Pain Using Body-Mounted Inertial Sensors

Abstract Perineural analgesia of the deep branch of the lateral plantar nerve (DBLPN block) and intraarticular analgesia of the tarsometatarsal joint (TMT block) are commonly used to differentiate pain originating from the distal tarsal and the proximal metatarsal areas in horses. However, both analgesic techniques have recently been subjected to close scrutiny, with questions raised as to their efficacy. The purpose of this study is to undertake an objective assessment of the effect of both diagnostic analgesia techniques on hindlimb lameness using a body‐mounted inertial sensor system (Lameness Locator; Equinosis LLC, Columbia, MO). Horses with chronic hindlimb lameness were instrumented with inertial sensors measuring vertical pelvic asymmetry in millimeters and underwent a routine lameness examination including diagnostic analgesia. Twenty‐seven horses showing an improvement in lameness after the DBLPN block were selected for the study. These horses underwent the TMT block on the following day. The change in vertical pelvic asymmetry after the DBLPN block was compared to the change following the TMT block. Of 27 horses, 17 showed improvement after the DBLPN block but not after the TMT block (group 1). The other 10 horses showed improvement in lameness after both analgesic techniques (group 2). The DBLPN block and the TMT block desensitized different structures in more than half of the horses. However, the possibility that both analgesic techniques can desensitize the same structures due to either the diffusion of the anesthetic agent or of an inadvertent injection still remains. HighlightsHorses could be divided into two groups according to response after the tarsometatarsal joint (TMT) block.Seventeen of 27 horses (63%) were considered having a negative TMT block.The rest (10/27, 37%) were considered having a positive TMT block.Improvement of lameness could already be detected at 5 minutes after TMT block.

Radiological prevalence of equine odontoclastic tooth resorption and hypercementosis

BACKGROUNDnEquine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful and progressive dental disease that mainly affects the incisors and canine teeth of aged horses. Diagnosis is based on radiographs to detect early stages of the disease. EOTRH is probably underdiagnosed and its prevalence in Germany unknown.nnnOBJECTIVEnThis study was performed to determine the radiological prevalence of EOTRH in a large horse population in Berlin-Brandenburg, Germany.nnnSTUDY DESIGNnPrevalence study.nnnMETHODSnThe study population (142 horses) consisted of all horses 10xa0years and older that were presented at the Equine Hospital for a routine dental examination. The horses were either presented as clinical cases (CC population) or belonged to a riding school (RS population). Digital radiographs of the incisor dentition were taken and evaluated for changes related to EOTRH, leading to an overall classification for each horse.nnnRESULTSnThe mean age of the study population was 21xa0years and ranged from 10 to 37xa0years. Overall, 94% of all horses had at least minor and 62% had moderate to severe radiological changes of the incisor teeth associated to EOTRH. No horse older than 14xa0years was without radiological signs of EOTRH and all horses over 28xa0years of age had at least moderate radiological changes of the incisor teeth.nnnMAIN LIMITATIONSnThe clinical cases group might have a bias towards horses with existing dental problems such as EOTRH, because they were presented explicitly for dental care to a clinic.nnnCONCLUSIONnFocusing on radiological changes, this study shows that EOTRH is a common condition of horses in Berlin-Brandenburg. With older age, disease is more frequent and radiological changes become more severe. Since no horse older than 14xa0years was without radiological findings, it is likely that mild changes may be associated with the normal tooth ageing process.