Reliability of surface electromyographic (sEMG) measures of equine axial and appendicular muscles during overground trot.

The reliability of surface electromyography (sEMG) has not been adequately demonstrated in the equine literature and is an essential consideration as a methodology for application in clinical gait analysis. This observational study investigated within-session, intra-subject (stride-to-stride) and inter-subject reliability, and between-session reliability of normalised sEMG activity profiles, from triceps brachii (triceps), latissimus dorsi (latissimus), longissimus dorsi (longissimus), biceps femoris (biceps), superficial gluteal (gluteal) and semitendinosus muscles in n = 8 clinically non-lame horses during in-hand trot. sEMG sensors were bilaterally located on muscles to collect data during two test sessions (session 1 and 2) with a minimum 24-hour interval. Raw sEMG signals from ten trot strides per horse and session were DC-offset removed, high-pass filtered (40 Hz), full-wave rectified, and low-pass filtered (25 Hz). Signals were normalised to peak amplitude and percent stride before calculating intra- and inter-subject ensemble average sEMG profiles across strides for each muscle and session. sEMG profiles were assessed using waveform similarity statistics: the coefficient of variation (CV) to assess intra- and inter-subject reliability and the adjusted coefficient of multiple correlation (CMC) to evaluate between-session reliability. Across muscles, CV data revealed that intra-horse sEMG profiles within- and between-sessions were comparatively more reliable than inter-horse profiles. Bilateral gluteal, semitendinosus, triceps and longissimus (at T14 and L1) and right biceps showed excellent between-session reliability with group-averaged CMCs > 0.90 (range 0.90-0.97). Bilateral latissimus and left biceps showed good between-session reliability with group-averaged CMCs > 0.75 (range 0.78-0.88). sEMG profiles can reliably describe fundamental muscle activity patterns for selected equine muscles within a test session for individual horses (intra-subject). However, these profiles are more variable across horses (inter-subject) and between sessions (between-session reliability), suggesting that it is reasonable to use sEMG to objectively monitor the intra-individual activity of these muscles across multiple gait evaluation sessions at in-hand trot.

The effect of cut-off frequency when high-pass filtering equine sEMG signals during locomotion.

High-pass filtering (HPF) is a fundamental signal processing method for the attenuation of low-frequency noise contamination, namely baseline noise and movement artefact noise, in human surface electromyography (sEMG) research. Despite this, HPF is largely overlooked in equine sEMG research, with many studies not applying, or failing to describe, the application of HPF. An optimal HPF cut-off frequency maximally attenuates noise while minimally affecting sEMG signal power, but this has not been investigated for equine sEMG signals. The aim of this study was to determine the optimal cut-off frequency for attenuation of low-frequency noise in sEMG signals from the Triceps Brachii and Biceps Femoris of 20 horses during trot and canter. sEMG signals were HPF with cut-off frequencies ranging from 0 to 80 Hz and were subjected to power spectral analysis and enveloped using RMS to calculate spectral peaks, indicative of motion artefact, and signal loss, respectively. Processed signals consistently revealed a low-frequency peak between 0 and 20 Hz, which was associated with motion artefact. Across all muscles and gaits, a 30-40 Hz cut-off fully attenuated the low-frequency peak with the least amount of signal loss and was therefore considered optimal for attenuating low-frequency noise from the sEMG signals explored in this study.

Comparing subjective and objective evaluation of show jumping competition and warm-up arena surfaces.

The development of safety and quality standards for equestrian surfaces needs to be based on objective, repeatable measurements which allow comparisons between surfaces. These measurements should incorporate the assessment of surface performance by riders. This study provides data from objective and subjective assessment of functional properties of high-level show jumping competition and warm-up arenas. Twenty-five arenas in nine international show jumping events were evaluated by mechanical in-situ testing with a surface tester, rider assessments using visual analogue scales (198 riders provided 749 arena evaluations), descriptions of arena constructions and by laboratory tests of surface material. Mixed models were used to present subjective evaluation of rider perception of the functional properties for each arena while controlling for rider and event. The association between objective and subjective assessments were also explored creating mixed models, controlling for rider and event. Mechanical measurements of impact firmness, and to a lesser extent cushioning and grip, had a significant positive association with the riders' perception. Responsiveness as assessed by the Orono biomechanical surface tester (OBST) was negatively associated with the riders' perceptions, which suggests riders and the OBST had different concepts of this functional property and that further developments of the OBST might be necessary. Objectively measured uniformity showed no useful association with riders' perception. Even though arena assessments were made by top level riders, a substantial inter-rider variation was demonstrated.

Ground reaction forces of elite dressage horses in collected trot and passage.

In this study, sagittal plane ground reaction forces (GRFs) in ridden elite dressage horses performing 'collected trot' and in 'passage' over ground were determined. In-ground force plates captured GRF data from four Dutch Warmblood and four Lusitano horses ridden by their trainers. At least three stance phases were analysed for forelimbs and hind limbs per horse. The variables extracted were vertical and longitudinal (braking, propulsive) force maxima, their times of occurrence and the respective impulses for forelimbs and hind limbs. Lusitanos had lower vertical impulses than Dutch Warmbloods in collected trot. Across all horses, passage had larger vertical impulses than collected trot in the forelimbs and hind limbs. Propulsive impulse increased in the hind limbs in passage. Prolonged stance durations in passage contributed to higher vertical impulses that are needed to increase the vertical excursions of the centre of mass.

A simple method for equine kinematic gait event detection.

BACKGROUND: Previous studies have validated methods for determining kinematic gait events using threshold-based techniques. However, a simple method that can be successfully applied to walk, trot and canter is yet to be identified. OBJECTIVES: To develop a simple kinematic method to identify the timing of hoof contact (hoof-on), peak vertical force and lift off (hoof-off), which can be applied in walk, trot and canter. STUDY DESIGN: In vivo method authentication study. METHODS: Horses (n = 3) were ridden in walk, trot and canter down a runway on which four force plates were arranged linearly. Three-dimensional forces were recorded at a sampling rate of 960 Hz and were synchronised with a 10-camera motion analysis system sampling at 120 Hz. Events identified from vertical ground reaction force (GRFz) data were hoof-on (GRFz>50N), peak vertical force (GRFzpeak ) and hoof-off (GRFz<50N). Kinematic identification of hoof-on and hoof-off events was based on sagittal planar angles of the fore- and hindlimbs. Peak metacarpophalangeal (MCP)/metatarsophalangeal (MTP) joint extension was used to assess the time of GRFzpeak . The accuracy (mean) and precision (s.d.) of time differences between kinetic and kinematic events were calculated for fore- and hindlimbs at each gait. RESULTS: Hoof-off was determined with better accuracy (range: -3.94 to 8.33 ms) and precision (range: 5.43-11.39 ms) than hoof-on across all gaits. Peak MCP angle (range: 5.83-19.65 ms) was a more precise representation of GRFzpeak than peak MTP angle (range: 11.49-67.75 ms). MAIN LIMITATIONS: The sample size was small and therefore further validation is required. The proposed method was tested on a single surface. CONCLUSIONS: This study proposes a simple kinematic method of detecting hoof-on, hoof-off and GRFzpeak at walk, trot and canter. Further work should focus on validating the methodology in a larger number of horses and should extend the method for use on surfaces with varying levels of compliance.

Plate failure by bending following tibial fracture stabilisation in 10 cats.

OBJECTIVE: To describe the clinical findings and management of tibial fractures in cats in which osteosynthesis failed due to plate bending. METHODS: Case records and radiographs of cat tibial fracture repairs from five referral centres were reviewed for signalment and to assess incidence of plate failure by bending. Cats that sustained plate bending following plate or plate-rod fixation were reviewed for fracture configuration, repair method, initial postoperative and postfailure tibial alignment, revision treatment and outcome. RESULTS: The incidence of plate bending in cat fractures managed with plate and plate-rod fixation in the four referral centres where the overall number could be established was 13% (8/60). In the 10 cats in which plates bent, initial fractures were generally oblique or spiral with mild comminution and located in the middle or distal third of the tibia. Mean time to implant failure was 24 days (range 2 to 56 days). Mean tibial valgus angle increased from 12·9° to 30·9° following bending of the plate. Short-term outcome following revision surgery using orthogonal plating or stacked medial plates was favourable with improvement in tibial valgus in all five fractures with follow-up data. CLINICAL SIGNIFICANCE: Plate bending following tibial fracture stabilisation in these 10 cats resulted in tibial valgus deformation. Consideration of plate and/or intramedullary rod selection and application should be given to avoid a plate strain environment that exceeds the yield point of the plate.

Treatment of cranial cruciate ligament rupture in the feline stifle. Biomechanical comparison of a standard fabella-tibial suture and lateral sutures placed between quasi-isometric points.

OBJECTIVE: To determine whether a lateral suture placed with bone anchors between quasi-isometric points in a cat is superior to a standard fabella-tibial suture for the stabilization of cranial cruciate ligament (CrCL) rupture compared to an intact stifle joint. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Six stifle joints with intact cruciate ligaments from three skeletally mature cats were placed in a loading mounting set and tested with axial loads of 20N and 60N at three different joint angles (75°,130° and 160°). The procedure was repeated with a transected CrCL; a stabilized stifle joint after a combination of three lateral suture techniques (fabella-tibial suture technique [SFT]; femoro-tibial suture technique 1 [FTS-1] and femoro-tibial suture technique 2 [FTS-2]). Radiographic examination of the relative position of the tibia to the fixed femur was compared. RESULTS: Stabilization of the stifle joint with lateral sutures had comparable stability to the intact specimens in the cranio-caudal direction (p = 0.2) but not in the proximo-distal direction for the SFT (p = 0.04) and FTS-2 technique (p = 0.03). There was no significant difference between the three stabilization techniques (p >0.05). CLINICAL SIGNIFICANCE: Lateral sutures placed with bone anchors at quasi-isometric points performed better than SFT and FTS-2 in stabilizing the feline stifle after CrCL rupture in the proximo-distal plane. Biomechanical stability in the cranio-caudal plane after placement of a lateral suture across the feline stifle was similar to the intact CrCL.

The Influence of Minimalist Footwear on Knee and Ankle Load during Depth Jumping.

Plyometric training is used by athletes to promote strength and explosive power. However plyometric activities such as depth jumping are associated with a high incidence of injuries. This study examined the influence of minimalist and conventional footwear on the loads experienced by the patellofemoral joint and Achilles tendon. Patellofemoral and Achilles tendon forces were obtained from ten male participants using an eight-camera 3D motion capture system and force platform data as they completed depth jumps in both footwear conditions. Differences between footwear were calculated using paired t-tests. The results show that the minimalist footwear were associated with significantly lower patellofemoral contact force/pressure and also knee abduction moment. It is therefore recommended, based on these observations, that those who are susceptible to knee pain should consider minimalist footwear when performing plyometric training.

Inter- and intraobserver agreement in interpretation of CT features of medial coronoid process disease.

OBJECTIVES: To evaluate inter- and intraobserver reliability of the assessment of computed tomography features commonly used in the identification and classification of medial coronoid process disease and to assess inter- and intraobserver variability in the identification of the percentage ulna sclerosis from single transverse computed tomography images. METHODS: Eight observers, on two occasions, reviewed 84 standardised single transverse computed tomography images acquired at the level of the apex of the medial coronoid process. Observers assessed: medial coronoid process disease, coronoid process fragmentation, osteophytes, sclerosis grade and sclerosis delineation with normal bone defined using a sclerometer. Cohen's kappa and intraclass correlation coefficient were calculated. RESULTS: Inter-observer agreement was fair to moderate for identification of computed tomography changes consistent with medial coronoid process disease, moderate to almost perfect for fragmentation, and moderate for osteophyte detection. Agreement was poor for sclerosis grading. Percentage sclerosis measured with a sclerometer had moderate to almost perfect inter- and intraobserver agreement. CLINICAL SIGNIFICANCE: These findings suggest that subjective assessment of computed tomography images is less repeatable than more quantitative methods.

Three-dimensional kinematic differences between the preferred and non-preferred limbs during maximal instep soccer kicking.

Abstract The current investigation aimed to determine whether there are differences in ball velocity and 3D kinematics when performing maximal kicks with the dominant and non-dominant limbs. Seventeen male academy soccer players performed maximal speed place kicks with their dominant and the non-dominant limbs. The 3D kinematics of the lower extremities were obtained using a 10-camera motion capture system operating at 500 Hz. Hip, knee and ankle joint kinematics were quantified in the sagittal, coronal and transverse planes and then contrasted using paired t-tests. Significantly higher ball velocities were obtained with the dominant limb. Foot linear velocity and knee extension velocity at ball contact were also found to be significantly greater in the dominant limb. That reduced ball velocities were observed between kicking limbs highlights the potential performance detriments that may occur when kicking with the non-dominant limb; thus, it is recommended that additional bilateral training be undertaken in order to attenuate this and improve overall kicking performance.

Patellar ligament rupture in the dog: repair methods and patient outcomes in 43 cases.

The medical records of dogs receiving surgery for unilateral patellar ligament rupture between 1999 and 2012 at 12 multidisciplinary referral centres were reviewed. Forty-three cases were identified; 26 were traumatic in origin; almost one-third were iatrogenic, of which over three-quarters occurred as a complication following surgical stabilisation of patellar luxation. Treatment involved primary reapposition of the ligament (36 cases). The repair was protected by circumpatellar and/or transpatellar loop(s) of orthopaedic wire, nylon, polypropylene or polydioxanone suture (34 cases). Wire loops were more likely to require surgical removal compared with loops of other materials (P=0.0014). The stifle joint was immobilised postoperatively by the applications of a transarticular external skeletal fixator (taESF) in 17 cases and by external coaptation (EC) in 8 cases; in 18 cases, no postoperative joint immobilisation was provided. Complications specific to the method of immobilisation occurred in seven of the cases with taESF and six of the cases with EC. Revision surgery to address failure of repair was required in five cases. Outcome was classified as acceptable or good in over three-quarters of the cases (31/40) and poor in less than a quarter (9/40). These data highlight patellar ligament rupture as a complication of surgical stabilisation of patellar luxation.

Complications of lateral plate fixation compared with tension band wiring and pin or lag screw fixation for calcaneoquartal arthrodesis. Treatment of proximal intertarsal subluxation occurring secondary to non-traumatic plantar tarsal ligament disruption in dogs.

OBJECTIVE: To compare complication rates and the outcomes of these complications after lateral plate fixation with figure-of-eight tension-band-wire and pin or lag screw fixation for arthrodesis of the calcaneoquartal joint, following non-traumatic disruption of the plantar tarsal ligament in dogs. METHODS: Data were collected retrospectively from five UK referral centres. Diplomate specialists and their residents performed all procedures. Referring veterinarians were contacted for long-term follow-up. RESULTS: Seventy-four procedures were undertaken in 61 dogs. There were 58 arthrodeses in the lateral plate group (Plate), nine in the pin and tension-band-wire group (Pin), and seven in the lag screw and tension-band wire-group (Screw). Compared to Plate (17%), further surgical intervention was required more frequently following Pin (56%, OR = 3.2) or Screw (43%, OR = 2.5) fixation. Clinical failure of arthrodesis occurred less frequently with Plate (5%) compared with Screw (43%, OR = 8.6) and Pin fixation (22%, OR = 4.4). Cases managed with external coaptation postoperatively were more likely to suffer from postoperative complications (OR = 2.2). CLINICAL SIGNIFICANCE: Lateral plating was associated with fewer postoperative complications than pin and tension-band-wire fixation for arthrodesis of the calcaneoquartal joint in dogs with non-traumatic disruption of the plantar tarsal ligament.

Long bone fracture as a complication following external skeletal fixation: 11 cases.

OBJECTIVES: To report on a series of dogs and cats with long bone fractures that occurred as a direct consequence of linear external skeletal fixation (ESF) application. METHODS: Retrospective study. Data from the medical records and radiographs of canine (n = 4) and feline (n = 7) cases were collected from three referral and three first opinion practices in the UK (1999 to 2011). RESULTS: Long bone fractures occurred following the application of linear ESF either while the ESF was in situ or after removal. All fractures occurred through either a pin tract or an empty drill hole. Pins associated with ESF-related fracture tended to be in the higher end of the recommended size range. The majority of cases had additional complicating factors such as multiple injuries, revision surgery, poor owner compliance with postoperative exercise restriction and the presence of empty drill holes. CLINICAL SIGNIFICANCE: In cases with features that could complicate outcome, careful attention should be paid to recommendations for ESF application. Leaving empty drill holes is suboptimal. The retrospective nature of the study, low numbers of, and diversity amongst, cases should be taken into consideration when interpreting the results from this study.

Influence of the helical and six available Cardan sequences on 3D ankle joint kinematic parameters.

Cardan/Euler and helical angles are the popular methods of quantifying angular kinematics. Cardan angles are sequence dependent and crosstalk can influence the kinematic calculations. The International Society of Biomechanics (ISB) recommends a sagittal, coronal, and then transverse (XYZ) sequence of rotations, although it has been proposed that when calculating rotations outside of the sagittal plane, this may not be the most appropriate method. This study investigated the influence of the helical and six available Cardan sequences on three-dimensional (3D) ankle joint kinematics. Kinematic data were obtained using an eight-camera motion analysis system as participants ran at 4.0 m/s +/- 5%. Repeated measures ANOVAs were used to compare kinematic parameters, and intraclass correlations were employed to identify evidence of crosstalk across planes. The results indicate that in the transverse and coronal planes, peak angle and range of motion values using the YXZ and ZXY sequences were significantly greater than the other sequences. Furthermore, utilization of YXZ and ZXY sequences was associated with the strongest correlations from the sagittal plane, and the XYZ sequence was found to be associated with the lowest correlations. It appears that for the representation of 3D ankle joint kinematics, the XYZ sequence is associated with minimal planar crosstalk and as such its use is encouraged.

Healing of patellar fractures in two kittens.

Two kittens aged between four and five months were presented having sustained patellar fractures. In both cases, healing was subsequently documented radiographically; this has not been reported previously in the literature. One kitten had bilateral patellar fractures - the symptomatic right stifle was treated with a pin and tension-band-wire which later failed, at which point partial patellectomy was performed. The fracture of the left patella was minimally displaced and was treated conservatively. A radiograph of the left patella taken eleven months after initial presentation showed complete healing of the fracture. The second case was treated surgically with a circumferential wire; healing of the fracture was demonstrated radiographically at twelve weeks postoperatively. Radiographic images taken five weeks postoperatively had shown some narrowing of the fracture gap. These two cases demonstrate that bony union of patellar fractures can be documented, given a long enough duration of radiographic follow-up; circumferential wire was an effective treatment in a displaced fracture, and conservative treatment resulted in complete healing of a minimally displaced fracture.

Modification of the cranial closing wedge ostectomy technique for the treatment of canine cruciate disease. Description and comparison with standard technique.

OBJECTIVE: To describe a modification of the cranial closing wedge ostectomy (CCWO) technique and to compare its efficacy to the standard technique on cadaveric specimens. METHODS: The standard and modified CCWO technique were applied to eight pairs of cadaveric tibiae. The following parameters were compared following the ostectomy: degrees of plateau levelling achieved (degrees), tibial long axis shift (degrees), reduction in tibial length (mm), area of bone wedge removed (cm²), and the area of proximal fragment (cm²). RESULTS: The size of the removed wedge of bone and the reduction in tibial length were significantly less with the modified CCWO technique. CLINICAL SIGNIFICANCE: The modified CCWO has two main advantages. Firstly a smaller wedge is removed, allowing a greater preservation of bone stock in the proximal tibia, which is advantageous for implant placement. Secondly, the tibia is shortened to a lesser degree, which might reduce the risk of recurvatum, fibular fracture and patella desmitis. These factors are particularly propitious for the application of this technique to Terrier breeds with excessive tibial plateau angle, where large angular corrections are required. The modified CCWO is equally effective for plateau levelling and results in an equivalent tibial long-axis shift. A disadvantage with the modified technique is that not all of the cross sectional area of the distal fragment contributes to load sharing at the osteotomy.

Salter-Harris type III fractures of the distal humerus in two dogs.

Salter-Harris type III fractures of the distal humerus in a four-month-old male Labrador Retriever and a male crossbreed dog (estimated to be 3.5-months-old) are reported. Both fractures were treated with open reduction and interfragmentary compression by lag screw fixation. Both fractures healed and full limb use was regained at four weeks postoperatively. The occurrence of this unusual fracture type may be related to the physeal closure pattern of the distal humeral physis, and a different mechanism of injury compared to the more common Salter-Harris type IV fracture seen in this region.

Regulation of NKB pathways and their roles in the control of Kiss1 neurons in the arcuate nucleus of the male mouse.

Kisspeptin (Kiss1) and neurokinin B (NKB) (encoded by the Kiss1 and Tac2 genes, respectively) are indispensable for reproduction. In the female of many species, Kiss1 neurons in the arcuate nucleus (ARC) coexpress dynorphin A and NKB. Such cells have been termed Kiss1/NKB/Dynorphin (KNDy) neurons, which are thought to mediate the negative feedback regulation of GnRH/LH secretion by 17ß-estradiol. However, we have less knowledge about the molecular physiology and regulation of Kiss1/Kiss1-expressing neurons in the ARC of the male. Our work focused on the adult male mouse, where we sought evidence for coexpression of these neuropeptides in cells in the ARC, assessed the role of Kiss1 neurons in negative feedback regulation of GnRH/LH secretion by testosterone (T), and investigated the action of NKB on KNDy and GnRH neurons. Results showed that 1) the mRNA encoding Kiss1, NKB, and dynorphin are coexpressed in neurons located in the ARC; 2) Kiss1 and dynorphin A mRNA are regulated by T through estrogen and androgen receptor-dependent pathways; 3) senktide, an agonist for the NKB receptor (neurokinin 3 receptor, encoded by Tacr3), stimulates gonadotropin secretion; 4) KNDy neurons express Tacr3, whereas GnRH neurons do not; and 5) senktide activates KNDy neurons but has no discernable effect on GnRH neurons. These observations corroborate the putative role for KNDy neurons in mediating the negative feedback effects of T on GnRH/LH secretion and provide evidence that NKB released from KNDy neurons is part of an auto-feedback loop that generates the pulsatile secretion of Kiss1 and GnRH in the male.

The difference in kinematics of horses walking, trotting and cantering on a flat and banked 10 m circle.

REASONS FOR PERFORMING STUDY: Locomotion adaptation mechanisms have been observed in horses, but little information is available in relation to banked and nonbanked curve locomotion, which might be important to optimise training environments. OBJECTIVES: To determine if adaptation mechanisms in horses existed when moving on a banked compared to a flat curve and whether adaptation was similar in different gaits. METHODS: Eight infrared cameras were positioned on the outside of a 10 m lungeing circle and calibrated. Retroreflective markers were used to define left and right metacarpus (McIII) and proximal phalanges (P1), metatarsus (MtIII), head and sacrum. Data were recorded at 308 Hz from 6 horses lunged at walk, trot and canter on a flat and 10° banked circle in a crossover design. Measurements extracted were speed, stride length, McIII inclination, MtIII inclination, relative body inclination and duty factor. Data were smoothed with a fourth order Butterworth filter with 30 Hz cut-off. ANOVA was used to determine differences between conditions and limbs. RESULTS: Adaptation mechanisms were influenced by gait. At canter inside forelimb duty factor was significantly longer (P<0.05) on a flat curve compared to a banked curve; at walk this was reversed. McIII inclination, MtIII inclination and relative body inclination were significantly greater (P<0.05) at trot and canter on a flat curve, so more inward tilt was found relative to the bearing surface. CONCLUSION: Adaptation to curved motion is gait specific. At faster gaits it appears that horses negotiate a banked curve with limb posture closer to body posture and probably with demands on the musculoskeletal system more similar to straight canter.