Using a modified vector coding technique to describe the calcaneus-shank coupling relationship during unanticipated changes of direction: theoretical implications for prophylactic ACL strategies.

Shank rotation is associated with increased risk in lower limb injuries of weight-bearing sport activity. Straight-line running injury prevention research proposes a 'bottom-up' approach to minimising injury risk to the knee. This prophylactic recommendation is due to the observed distal-proximal coupling relationship between rearfoot and shank rotations. However, the coupling relationship between the calcaneus and shank is unknown in sports with high intensity decelerations, frequent changes of direction, associated with increased anterior cruciate ligament (ACL) injury risk. The aim of this study was to determine whether the movement of the calcaneus has a potential effect on the internal and external rotational movement of the shank, associated with ACL injury risk. We implemented a modified vector coding technique using segmental velocities in a local, anatomical reference frame to quantify the coupling relationship between the individual tri-planar calcaneus rotations and transverse plane shank rotations. During the loading phase, a distal-proximal coupling relationship between calcaneus eversion deceleration, abduction acceleration, and shank internal rotation deceleration was observed amongst most subjects. The distal-proximal coupling found between the calcaneus and shank justifies exploring interventions geared towards manipulating calcaneus motion to affect shank rotational movements during unanticipated change of direction tasks associated with ACL injury risk.

Development of An Anybody Musculoskeletal Model of The Thoroughbred Forelimb.

Musculoskeletal injuries in horses are the main cause of retirement, rest, and death. To understand these injuries, it is necessary to study loads in muscles, tendons and ligaments. A musculoskeletal model makes it possible to consider all structures simultaneously and avoids invasive measurements. At present, most computational models of the equine limb described in the literature have been limited to the distal limb. The aim of this study was to create a preliminary musculoskeletal model of the whole equine forelimb and to run it with kinematic data collected during gait. The model was developed with the AnyBody Modelling System. It includes six limb segments, 11 muscle groups and 17 ligaments. Kinematic data were collected from the right forelimb of four Thoroughbreds at trot, right and left lead canter, and were then used in the model to compute sagittal plane joint excursions and ligament and tendon strains. The modelled joint excursions were in reasonable agreement with previous reports in the literature despite breed, gait and surface differences. Strain patterns of the tendons of the suspensory apparatus agreed with the literature, with maxima in mid-stance or at the end of stance. Strains in the distal palmar ligaments peaked in mid-stance, while strain in lacertus fibrosus peaked at the stance-swing transition. Tendon and ligament strains at canter were greatest when the measured forelimb was the trailing limb. Strain amplitudes varied against earlier models and these differences are discussed in relation to variations in methods, and especially in relation to attachment points of tendons and ligaments.

A Novel Load Cell-Supported Research Platform to Measure Vertical and Horizontal Motion of a Horse's Centre of Mass During Trailer Transport.

During transport, horses are subjected to acceleration in three dimensions, rapid braking, turning, noise, and other stressors. The animal's ability to make postural corrections may be insufficient to prevent injury or distress, and so knowledge of the compensatory motion patterns of the horse in the trailer is a necessary precondition for smart design of transport systems. A custom two-horse trailer was built for this project. It had a horse compartment 1.85 m wide by 3.95 m long, with adjustable bulkheads and a centre divider separating the horses. The floor was instrumented with 24 shearbeam load cells to measure the vertical load imposed by each horse and its horizontal motion. Two horses were driven on a 56 km trip on both rural and urban roads. Load data were collected at 100 Hz for the 58-minute trip and were filtered with a cut-off frequency of 5 Hz using a Butterworth low-pass filter and then vertical acceleration computed. A pivot table counted sign reversals in the vertical acceleration signal, and vertical displacement was calculated using the fundamental frequency of the resulting acceleration data. Total vertical motion was calculated by making the negative displacements absolute and summing these with the positive displacements, and vertical work done was calculated by multiplying the force by the displacement measures. Horizontal motion was calculated by averaging the transverse and cranio-caudal position of the centre of pressure every second and adding the resultant displacements. Absolute vertical displacement of the two horses was 69.55 m and 97.56 m. In addition to the work done by standing, vertical work done in response to vibration was 322.4 kJ and 443.2 kJ. Horizontal excursion was 227.1 m and 243.0 m. This is a first effort to quantify the additional workload imposed on animals during transport, which will aid in the design of smart transport vehicles that will minimize the stress to horses.

Foot Muscle Strengthening and Lower Limb Injury Prevention.

Background and objectives: The active and passive structures of the foot act in unison to not only be compliant enough to assist in ground reaction force attenuation but also resist deformation to provide a stable base of support. A foot that is unable to adjust to the imposed demands during high-intensity sporting activities may alter the moments and forces acting on the joints, increasing the risk of non-contact anterior cruciate ligament ruptures (ACLR) and lateral ankle sprains (LAS). Prophylactic strengthening programs are often used to reduce the risk of these injuries, but at present, very few prophylactic programs include foot-specific strengthening strategies. The aim of this theoretical review is to ascertain the prophylactic role strengthening muscles acting on the foot may have on ACLR and LAS injury risk. Methods: Literature relating to risk factors associated with ACLR and LAS injury and the anatomy and biomechanics of normal foot function was searched. In addition, ACLR and LAS injury prevention programs were also sought. A theoretical, narrative approach was followed to synthesize the information gathered from the articles. Results: The foot segments are governed by the congruity of the articulations and the activity of the foot muscles. As such, there is a coupling effect between shank, calcaneus, midfoot, and hallux movement which play a role in both ACLR and LAS injury risk. Conclusions: Strengthening the muscles acting on the foot may have a significant impact on ACLR and LAS injury risk.

The coordination patterns of the foot segments in relation to lateral ankle sprain injury mechanism during unanticipated changes of direction.

Preventing lateral ankle sprain injuries (LAS) in females competing in court sports is a high priority, as an athlete's risk for re-injury and developing long term dysfunction increases significantly after sustaining an acute LAS. Stability to the ankle joint is passively provided by the joint congruity and ligaments, and actively by the muscles acting on the foot. The ankle joint is most stable when loaded and dorsiflexed. However, during unanticipated changes of direction, typical in court sports, the foot is often in a vulnerable unloaded, plantarflexed position. Stability of the forefoot and controlling rearfoot movement to avoid excessive ankle inversion and adduction thus becomes imperative. Information regarding the coupling relationship between the forefoot (hallux and metatarsal segments) and the rearfoot (calcaneus segment) during unanticipated changes of direction is lacking. The aim of this study was to supplement current LAS prophylactic knowledge by describing and quantifying hallux-calcaneus and metatarsal-calcaneus coupling. The coupling angles between sagittal plane hallux, tri-planar metatarsal and frontal- and transverse plane calcaneus movement, respectively, were calculated with a modified vector coding technique which used segmental velocities in a local, anatomical reference frame instead of segmental angles in a global reference frame. Coupling relationships revealed anti-phase movement between sagittal- metatarsal and frontal plane calcaneus movement throughout stance. During loading, sagittal- and frontal plane metatarsal acceleration/deceleration were coupled with frontal-transverse plane calcaneus acceleration/deceleration respectively. The remainder of the braking phase was characterized by calcaneus eversion deceleration. During propulsion, the hallux and metatarsal segments increased plantar flexion velocity in response to calcaneus inversion and adduction acceleration. As the forefoot was the only point of contact during stance, the coupling between segments were most likely neuromuscular. Strengthening intrinsic and extrinsic foot muscles may thus contribute to foot and ankle stability, adding to current prophylactic LAS strategies.

Elastic properties of collateral and sesamoid ligaments in the forelimbs of equine cadavers.

OBJECTIVE: To evaluate the elastic modulus of various ligaments of the forelimbs of cadaveric horses. SAMPLE: 408 ligaments from 37 forelimbs of 10 Thoroughbred cadavers and cadavers of 9 other horse breeds. PROCEDURES: Collateral ligaments and straight and oblique sesamoid ligaments were harvested from the proximal interphalangeal, metacarpophalangeal, carpal, and elbow joints of both forelimbs of all 19 horses. Ligament dimensions were measured, and the elastic modulus was determined by tensile testing the ligaments with a strain rate of 1 mm•s-1. RESULTS: Elastic modulus of the ligaments differed significantly among joints. Highest mean ± SE elastic modulus was for the medial collateral ligament of the metacarpophalangeal joints of Thoroughbreds (68.3 ± 11.0 MPa), and the lowest was for the lateral collateral ligament of the elbow joints of other breeds (2.8 ± 0.3 MPa). Thoroughbreds had a significantly higher elastic modulus for the collateral ligaments of the proximal interphalangeal and metacarpophalangeal joints, compared with values for the other breeds. There was large variation in elastic modulus. Elastic modulus was negatively affected by age. In the ligaments in the distal aspect of the forelimbs, elastic modulus was negatively affected by height at the highest point of the shoulders (ie, withers). CONCLUSIONS AND CLINICAL RELEVANCE: Cross-sectional area and elastic modulus of collateral ligaments in the forelimbs of equine cadavers differed between breeds and among joints, which may have been reflective of their relative physiologic function under loading during exercise.

A review of the cellular and molecular effects of extracorporeal shockwave therapy.

Extracorporeal shockwave therapy (ESWT) is a novel therapeutic modality and its use in promoting connective tissue repair and analgesic effect has been advocated in the literature. It is convenient, cost-effective, and has negligible complications; it therefore bypasses many of the problems associated with surgical interventions. This paper reviews the proposed mechanisms of action in promoting tissue repair and regeneration as well as analysing its efficacy providing an analgesic effect in clinical applications. Further research will be required to not only identify the underlying mechanisms more precisely, but will also be critical for ensuring consistency across the literature so that the most beneficial treatment protocol can be developed. Extracorporeal shockwave therapy stands as a promising alternative modality in promoting tissue repair.

Patellar instability and quadriceps avoidance affect walking knee moments.

PURPOSE: To classify patients with patellofemoral (PF) instability on the basis of their mechanical gait characteristics, and to relate gait deficits to patellofemoral congruence. METHODS: Thirteen patients awaiting patellar stabilisation surgery were recruited for gait analysis and magnetic resonance imaging, MRI assessment of PF congruence. Patients were grouped into two subgroups (P1, P2) based on knee joint moment during stance, and their total support moments (TSMs) during stance were compared against eight healthy Control subjects. PF congruence was compared between groups from MRI data captured at 0, 20 and 40° of passive knee flexion and during dynamic extension. RESULTS: Five patients were classified into group P1 because they demonstrated a knee extensor moment during early stance, and eight patients into group P2 because they did not. The TSM of the more affected limb in group P1 was not significantly different from Control values in early stance but the difference was significant (P<.05) in late stance. In group P2, both the less and more affected limbs were significantly different from Control TSM values in early stance, but only the more affected limb in late stance. Patellofemoral contact areas as measured by MRI were greatest for the Control patients, and least for patient group P2 especially during the active extension trials. CONCLUSIONS: Patients with patellofemoral pain and instability walked with a slightly flexed knee, avoiding extension. The MRI measurements of joint contact agreed with the patient groupings according to gait mechanics. Cartilage contact across the PF joint can be an objective measure of instability.

Kinematic analysis quantifies gait abnormalities associated with lameness in broiler chickens and identifies evolutionary gait differences.

This is the first time that gait characteristics of broiler (meat) chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n = 10) would be intermediate to those of lame broilers (n = 12) and jungle fowl (n = 10, tested at two ages: immature and adult). Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy) and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers) presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity) presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated with instability. We envisage a key future role for this highly quantitative methodology in pain assessment (associated with broiler lameness) including experimental examination of therapeutic agent efficacy.

Inverse dynamics analysis evaluation of tibial tuberosity advancement for cranial cruciate ligament failure in dogs.

OBJECTIVE: To evaluate, using inverse dynamic analysis, the biomechanical outcome from tibial tuberosity advancement (TTA) surgery in dogs affected by unilateral cranial cruciate ligament failure (CCLF). STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 13) 11-20 months after surgery. METHODS: Kinematic and force data were collected from 13 dogs 11-20 months after TTA and inverse dynamics analysis of the dogs' pelvic limb mechanical function performed. Angle, moment, and power were calculated for each joint. Total support moment (TSM) was calculated. RESULTS: Six dogs were affected on the right side (Raff) and 7 on the left (Laff). Peak stifle flexor moment was significantly larger for the right stifle compared with the left in Laff dogs, but similar in Raff dogs. Peak stifle extensor moment was significantly larger for the left stifle compared with the right in Raff dogs, and was also larger for the left stifle compared with the right in Laff dogs. Stifle power in early stance was larger on the left in Raff dogs and significantly larger on the right in Laff dogs. TSM was larger on the right in Raff dogs and significantly larger on the right in Laff dogs. CONCLUSIONS: Affected limbs had a reduction in power of the stifle flexors. Irrespective of the side of CCLF, TSM was larger on the right side and the stifle extensor moment in late stance was larger on the left, perhaps indicating a mechanical limb dominance effect.

Conservative versus arthroscopic management for medial coronoid process disease in dogs: a prospective gait evaluation.

OBJECTIVE: To investigate, using objective gait analysis, the long-term outcome of dogs with medial coronoid process disease (MCPD) treated with conservative management (CM) versus arthroscopic treatment (AT). STUDY DESIGN: Prospective clinical trial. ANIMALS: Dogs (n = 20) with unilaterally confirmed MCPD. METHODS: Eleven dogs were treated arthroscopically with removal of coronoid fragments and burring of any associated chondromalacic cartridge and 9 dogs were managed conservatively. All dogs were administered a 6-week course of oral tepoxalin on enrollment. Inverse dynamics gait analysis was performed at initial presentation and at 4, 8, 26, and 52 weeks. The gait variables analyzed were elbow moment (EM), elbow power (EP), total support moment (TSM), and total support moment ratio (TSMR) as a measure of forelimb asymmetry. RESULTS: Affected peak EM increased from 0.58 to 0.76 Nm/kg in the AT dogs, and from 0.66 to 0.81 Nm/kg in the CM dogs and there was no significant difference between groups. Affected peak EP increased marginally in the AT dogs, but was unchanged in the CM dogs and there was no significant difference between groups. TSM increased from 1.49 to 1.92 Nm/kg in the AT dogs and from 1.52 to 2.06 Nm/kg in the CM dogs and there was no significant difference between groups. TSMR was statistically different between treatment groups at 1 (P = .003) and 2 months (P = .048) with the AT group more asymmetric and hence more lame. TSMR at 12 months was 0.83 (AT) and 0.86 (CM) implying a failure of return to soundness by either group. CONCLUSIONS: AT dogs had increased mechanical asymmetry at 4 and 8 weeks compared to the CM group revealing surgery worsened limb function. There was no significant difference in mechanical symmetry between groups at 26 and 52 weeks.

Symmetry of hind limb mechanics in orthopedically normal trotting Labrador Retrievers.

OBJECTIVE: To evaluate symmetry of the hind limbs in orthopedically normal trotting dogs. Animals-19 orthopedically normal Labrador Retrievers with no history of lameness. PROCEDURES: Retroreflective markers were applied to the hind limb joints, and a 4-camera kinematic system captured positional data at 200 Hz in tandem with force platform data collection while the dogs trotted. Morphometric data were combined with kinematic and force data in an inverse dynamics method to calculate net joint moments and powers at the joints as well as total support moment for each limb. Dogs were identified as right or left dominant when their total support moment was > 10% asymmetric between sides. RESULTS: 10 of the 19 dogs were mechanically dominant in the right hind limb as determined by their total support moments. One dog was left dominant, and the remaining 8 were symmetric. Right-dominant dogs had larger net joint moments at the right hip, tarsal, and metatarsophalangeal joints and a smaller moment at the right stifle joint, compared with values for the left hind limb. The 1 left-dominant dog had the exact opposite findings. Hip and stifle joint moments and powers varied between limbs of the right-dominant and left-dominant groups in the timing of their transition from negative to positive, and power amplitudes varied at the hip, tarsal, and metatarsophalangeal joints but not the stifle joint. CONCLUSIONS AND CLINICAL RELEVANCE: Sound trotting dogs can have asymmetries in limb and joint mechanics. These natural mechanical asymmetries should be taken into account when considering models to evaluate stresses at joints and when considering surgery for cruciate ligament rupture.

Transverse and dorso-ventral changes in thoracic dimension during equine locomotion.

Changes in shape of the equine thorax during locomotion are not well defined, although it has been shown recently that the transverse hemi-diameter changes its dimension by up to 80mm on the side of the trailing forelimb during gallop, despite minimal change in thoracic circumference. The aim of this project was to analyse transverse and dorso-ventral changes in shape of the thorax simultaneously, and to determine if leading limb, treadmill slope and speed have an effect on these shape changes. Reflective markers were placed on the horse's hemi-thorax and movement of the markers was recorded using a motion capture system while the horse trotted and cantered on a treadmill. Treadmill speed and slope, and the lead the horse cantered on were varied to determine the effects these had on transverse hemi-diameter and dorso-ventral diameter. There was a negative correlation between transverse and dorso-ventral changes in thoracic dimension, the strength of which increased with speed on the trailing limb side. On the leading side, the relationship was either weakly negative or positive. The changes in dimension of the hemi-thorax were significantly greater on the trailing side compared to the leading side. Speed had small effects on thoracic shape changes, but inclined exercise caused an increase in transverse hemi-diameter on the trailing side of the thorax. The changes in thoracic shape are unlikely to contribute substantially to ventilation and rib motion is likely to be due to protraction and retraction of the forelimbs. However, it may reflect asynchronous ventilation of lung lobes and partially explain the prevalence of exercise-induced pulmonary haemorrhage.

Effect of trotting velocity on work patterns of the hind limbs of Greyhounds.

OBJECTIVE: To quantify the effects of trotting velocity on joint angular excursions, net joint moments, and powers across the hind limb joints in Greyhounds. ANIMALS: 5 healthy Greyhounds with no history of lameness of the hind limbs. PROCEDURES: Small reflective markers were applied to the skin over the joints of the hind limbs, and a 4-camera kinematic system was used to record positional data at 200 Hz in tandem with force platform data while the dogs trotted on a runway at slow, medium, and fast velocities. Breed-specific morphometric data were combined with kinematic and force data in an inverse-dynamics solution for net joint moments and powers at the hip, stifle, tarsal, and metatarsophalangeal joints. RESULTS: Angle, moment, and power patterns at the various joints were conserved among the 3 velocities. With increasing velocity, moments and powers at the tarsal, stifle, and hip joints during the stance phase were increased in amplitude, whereas amplitudes during the swing phase were not. The main contributors to increased velocity were the hip extensors and stifle flexors during the early part of the stance phase and the tarsal extensors during the late part of the stance phase. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in trotting velocity in Greyhounds do not alter the basic patterns of work and power for various joints of the hind limbs, but local burst amplitudes during the stance phase increase incrementally.

Distribution of power across the hind limb joints in Labrador Retrievers and Greyhounds.

OBJECTIVE: To quantify angular excursions; net joint moments; and powers across the stifle, tarsal, and metatarsophalangeal (MTP) joints in Labrador Retrievers and Greyhounds and investigate differences in joint mechanics between these 2 breeds of dogs. ANIMALS: 12 clinically normal dogs (6 Greyhounds and 6 Labrador Retrievers) with no history of hind limb lameness. PROCEDURE: Small retroreflective markers were applied to the skin over the pelvic limb joints, and a 4-camera kinematic system captured data at 200 Hz in tandem with force platform data while the dogs trotted on a runway. Breed-specific morphometric data were combined with kinematic and force data in an inverse-dynamics solution for stance-phase net joint moments and powers at the stifle, tarsal, and MTP joints. RESULTS: There were gross differences in kinematic patterns between Greyhounds and Labradors. At the stifle and tarsal joints, moment and power patterns were similar in shape, but amplitudes were larger for the Greyhounds. The MTP joint was a net absorber of energy, and this was greater in the Greyhounds. Greyhounds had a positive phase across the stifle, tarsal, and MTP joints at the end of stance for an active push-off, whereas for the Labrador Retrievers, the only positive phase was across the tarsus, and this was small, compared with values for the Greyhounds. CONCLUSIONS AND CLINICAL RELEVANCE: Gross differences in pelvic limb mechanics are evident between Greyhounds and Labrador Retrievers. Joint kinetics in specific dogs should be compared against breed-specific patterns.