Effects of 'navicular' shoeing on equine distal forelimb kinematics on different track surface.

Orthopaedic shoeing applied for disorders such as navicular disease is mostly evaluated on hard track surfaces, but very often horses are ridden only on soft tracks. To compare the effects of normal shoes, eggbar shoes, and shoes with heel wedges (5 degrees) on the kinematics of the distal forelimb on hard and soft track surfaces, eleven sound Dutch Warmblood horses were led across three different tracks (an asphalt, a fibre/sand mix (= Agterberg), and a pure sand track) with three different shoe types (a normal shoe, an eggbar shoe, and a shoe with heel wedges). The hoof rotation and the maximal extension of the fetlock joint at midstance period were recorded by an infrared-light based gait analysis system (ProReflex) at walk and at trot. Statistical analysis revealed significant effects of track and shoe type, and a shoe-track interaction (p<0.05). On soft track surfaces, the equilibrium of the distal forelimb dictated a 1.5-4 degrees forward rotation of the normal or eggbar shod foot, the most on a sand track. The wedge effect on hoof rotation, however, was always significantly greater, but similar to that on the hard track surface (5 degrees forward rotation). The maximal fetlock extension was less on a soft surface, in particular on the sand track (p<0.05). This decrease was most pronounced when the horses were shod with heel wedges and was least pronounced with normal shoes. In conclusion, in particular the sand track allows a forward rotation of the hoof and thus relief of pressure in the navicular area, and a decrease in maximal fetlock extension and thus unloading of the fetlock joint. The extra forward rotation of the hoof induced by heel wedges on hard tracks was almost the same on soft track surfaces. Eggbars and fibre/sand mix tracks have intermediate effects on unloading of the distal forelimb.     

Three-dimensional kinematics of the distal forelimb in horses trotting on a treadmill and effects of elevation of heel and toe

REASONS FOR PERFORMING STUDY: Comprehensive understanding of the 3-dimensional (3D) kinematics of the distal forelimb and precise knowledge of alterations induced by dorsopalmar foot imbalance remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. OBJECTIVE: To quantify the effects of 6 degree heel or toe wedges on the 3D movements of the 4 distal segments of the forelimb in horses trotting on a treadmill. METHODS: Three healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while horses were trotting on a treadmill. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with 6 degree heel or toe wedges were compared to those obtained with flat standard shoes. RESULTS: Use of heel wedges significantly increased maximal flexion and decreased maximal extension of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints. Inverse effects (except for PIPJ maximal extension) were observed with the toe wedges. In both cases, neither flexion-extension of the metacarpophalangeal joint nor extrasagittal motions of the digital joints were statistically different between conditions. CONCLUSIONS: At a slow trot on a treadmill, heel and toe wedges affect the sagittal plane kinematics of the interphalangeal joints. POTENTIAL RELEVANCE: Better understanding of the actual effects of toe and heel wedges on the 3D kinematics of the 3 digital joints may help to improve clinical use of sagittal alteration of hoof balance in the treatment of distal forelimb injuries.     

Development and evaluation of a noninvasive marker cluster technique to assess three-dimensional kinematics of the distal portion of the forelimb in horses

OBJECTIVE: To develop and evaluate a marker cluster set for measuring sagittal and extrasagittal movement of joints in the distal portion of the forelimb in ponies. ANIMALS: 4 ponies. PROCEDURES: 5 infrared cameras were positioned on a concrete walkway in a frontal-sagittal arc and calibrated. Four segments were defined: hoof, middle phalanx, proximal phalanx, and metacarpus. Rigid clusters with 4 retroreflective markers were placed on each segment. A static trial was recorded with additional anatomic markers on the medial and lateral joint lines. Those anatomic markers were removed, and kinematic data were recorded at 240 Hz during walking. An ensemble mean was computed from the 4 ponies from 5 replicates of the walks. Joint kinematic variables were calculated by use of the calibrated anatomical system technique. The design and error dispersion of each marker were evaluated. RESULTS: Marker clusters were quasiplanar, but variation in orientation error was reduced because the mean radii were > 10 times the largest error dispersion values. Measurements of sagittal rotations of the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints were similar to measurements obtained with bone-fixed triads, but larger discrepancies between the 2 methods were found for extrasagittal rotations. CONCLUSIONS AND CLINICAL RELEVANCE: Development of noninvasive methods for quantifying data pertaining to 3-dimensional motion in horses is important for advancement of clinical analysis. The technique used in the study enabled identification of flexion-extension motions with an acceptable degree of accuracy. Appropriate correction algorithms and improvements to the technique may enable future quantification of extrasagittal motions.     

Three-dimensional kinematics of the equine distal forelimb: effects of a sharp turn at the walk

REASONS FOR PERFORMING STUDY: Sharp turns are suspected to increase expression of several distal forelimb lamenesses even at the walk but the biomechanical consequences of such a movement remain unknown. OBJECTIVE: To quantify the effects of a sharp turn at the walk on the 3-dimensional movements of the distal segments of the forelimb. METHODS: Kinematics of the distal segments were measured in 4 healthy horses invasively with an ultrasonic system. Three-dimensional rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained for a turn at the walk were compared to those obtained in a straight line. RESULTS: During the stance phase in a turn, the inside forelimb underwent an adduction that induced lateromotion and medial rotation in the distal interphalangeal joint and medial rotation in the proximal interphalangeal joint. These movements were maximal at heel-off and decreased during breakover as the hoof underwent a sudden lateral rotation. CONCLUSIONS: Walking in a sharp turn affects the kinematics of the digital joints outside the sagittal plane. POTENTIAL RELEVANCE: This knowledge offers the opportunity to derive hypotheses on biomechanical factors that could contribute to the pathogenesis of digital injuries and on consequences for rational shoeing.     

Vascular distribution of contrast medium during intraosseous regional perfusion of the distal portion of the equine forelimb

OBJECTIVE: To describe the vascular distribution pattern of contrast medium during intraosseous regional perfusion (IORP) of the distal portion of the equine forelimb. SAMPLE POPULATION: 13 cadaveric forelimbs from 12 horses without forelimb diseases. PROCEDURES: Serial lateromedial radiographic views were taken of the distal portion of 10 heparinized cadaveric forelimbs at 0, 1, 2, 6, 15, and 30 minutes during IORP of the third metacarpal bone (MCIII) by use of iodinated contrast medium and a tourniquet placed over the proximal portion of MCIII. Vascular regions of interest (ROI) were created for each radiograph. Reviewers identified the presence or absence of contrast medium-induced opacified vessels in all ROI on radiographs. This information was summarized to identify vessel-filling patterns over time. Vessel identification was verified by use of computed tomography angiography and latex perfusion studies on the distal portion of separate cadaveric forelimbs. RESULTS: During IORP, contrast medium filled the medullary cavity of the MCIII; exited via transcortical vessels; and diffused distally to the remaining arteries and veins of the forelimb, distal to the tourniquet. Maximum vessel and soft tissue opacification occurred in most specimens at 6 and 30 minutes, respectively. Serial radiography vessel patterns matched those of computed tomography images and dissected specimens. CONCLUSIONS AND CLINICAL RELEVANCE: IORP provides a repeatable pattern of vascular distribution in the distal portion of the equine forelimb. To our knowledge, our study provides the first documentation of arterial perfusion by use of IORP; results of previous reports indicate that IORP delivers medications to only the venous vessels of the perfused forelimb.     

Effect of heel elevation on forelimb conformation in horses

OBJECTIVE: To determine the conformational changes in the distal forelimb of horses following heel elevation of 15 degrees and greater. An experimental study with repeated, within-horse measurements. PROCEDURE: Five clinically normal, mixed-breed horses were used to determine distal forelimb conformation following heel elevation from 0 to 45 degrees in 15 degree increments. Data were also compared to conformation of the limb in a Kimzey splint. Conformation was determined using lateral to medial radiographic projections. Conformation parameters assessed included measurement of apparent lengths of digital flexor tendons from the origin of their accessory ligaments to the points of insertion, and the joint angles of the distal limb. RESULTS: For angles of heel elevation from 15 to 45 degrees, the degree of joint angulation increased (increasing flexion) with heel elevation for the metacarpophalangeal, and proximal and distal interphalangeal joints. Conversely, the measured apparent lengths of the digital flexor tendons in the distal limb, decreased. CONCLUSION: The data supports the practice of elevating the heel (greater than 15 degrees) for conditions in which decreased fetlock extension may be desired such as with laceration or injury to the digital flexor tendons. Further study is required to determine whether heel elevation greater than 15 degrees reduces in vivo digital flexor tendon tension and also to ensure that the marked flexion of the distal interphalangeal joint with greater heel elevation is not detrimental over a prolonged period that may be required for the rehabilitation of flexor tendon injuries in the horse.     

Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb.     

Fractures of the distal phalanx of the forelimb in eight foals

Fractures of the distal phalanx of the forelimb were diagnosed in 5 colts and 3 fillies ranging in age from 2 weeks to 5 1/2 months at the time of fracture. Three fractures entered the distal interphalangeal joint and 6 fractures (one foal had bilateral fractures) were nonarticular. All foals with articular fractures became sound with conservative treatment. Four of 5 foals with nonarticular fractures became sound with conservative treatment and 1 foal developed separation of the hoof at the coronary band after application of acrylic around the hoof. On the basis of our observations in these foals, sagittal articular and nonarticular distal phalangeal fractures in foals should be treated conservatively. Foals so treated would have an excellent prognosis for return to soundness.     

Fractures of the distal phalanx in the horse

Fractures of the distal phalanx are an important cause of lameness referrable to the foot. Depending on the fracture configuration and articular involvement, conservative or surgical treatment may be required. Fractures of the distal phalanx have been divided into six categories based on fracture configuration. Discussion of clinical features, management, and prognosis for horses with distal phalangeal fractures is presented for each fracture type.     

2D versus 3D in the kinematic analysis of the horse at the trot

The handled trot of three Lusitano Purebred stallions was analyzed by using 2D and 3D kinematical analysis methods. Using the same capture and analysis system, 2D and 3D data of some linear (stride length, maximal height of the hoof trajectories) and angular (angular range of motion, inclination of bone segments) variables were obtained. A paired Student T-test was performed in order to detect statistically significant differences between data resulting from the two methodologies With respect to the angular variables, there were significant differences in scapula inclination, shoulder angle, cannon inclination and protraction-retraction angle in the forelimb variables, but none of them were statistically different in the hind limb. Differences between the two methods were found in most of the linear variables analyzed.     

Basic three-dimensional kinematics of the vertebral column of horses walking on a treadmill

OBJECTIVE: To determine kinematic movements of the vertebral column of horses during normal locomotion. ANIMALS: 5 Dutch Warmblood horses without apparent lameness or problems associated with the vertebral column. PROCEDURE: Kinematics of 8 vertebrae (T6, T10, T13, T17, L1, L3, L5, and S3) and both tuber coxae were determined, using bone-fixated markers. Horses were recorded while walking on a treadmill at a constant speed of 1.6 m/s. RESULTS: Flexion-extension was characterized by 2 periods of extension and flexion during 1 stride cycle, whereas lateral bending and axial rotation were characterized by 1 peak and 1 trough. The range of motion for flexion-extension was fairly constant for vertebrae caudal to T10 (approximately 7 degrees). For lateral bending, the cranial thoracic vertebrae and segments in the pelvic region had the maximal amount of motion, with values of up to 5.6 degrees. For vertebrae between T17 and L5, the amount of lateral bending decreased to <4 degrees The amount of axial rotation increased gradually from 4 degrees for T6 to 13 degrees for the tuber coxae. CONCLUSIONS: This direct measurement method provides 3-dimensional kinematic data for flexion-extension, lateral bending, and axial rotation of the thoracolumbar portion of the vertebral column of horses walking on a treadmill. Regional differences were observed in the magnitude and pattern of the rotations. Understanding of the normal kinematics of the vertebral column in healthy horses is a prerequisite for a better understanding of abnormal function.     

Resection of a premaxilla and rostral portion of the maxilla in a horse

A 5‐year‐old, 520 kg Standardbred mare was admitted for an osteosarcoma of the right premaxilla. Two horizontal incisions of the labial mucosa and lingual surface were made 1 cm around the ulceration from the canine tooth to the premaxillary symphysis. The premaxilla and rostral portion of the maxilla were transected 1 cm caudal to the canine tooth with an oscillating saw. The maxillary symphysis was transected using an oscillating saw and a hammer. The wound was closed by primary intention and healed without complication. The cosmetic appearance of the mare was good. The mare was able to prehend hay and grain and grazed without difficulty and the tongue did not protrude. The neoplasm had not recurred 18 months after the surgery. A premaxilla and rostral portion of the adjacent maxilla can be resected to treat horses for a unilateral lesion of the premaxilla but care must be taken to avoid the palatine and incisive arteries which lie within the interincisive canal.     

A large cyst in the distal femur of a horse

A 10-year-old Warmblood gelding presented with a left hindlimb lameness. Diagnostic analgesia located the lameness to the stifle. Radiography showed an unusually large cyst in the distal femur. Diagnostic arthroscopy of the stifle did not reveal any significant abnormalities. An extra-articular transcortical approach to the cyst was performed for drainage, curettage, and provision of an autologous, cancellous bone graft, gentamicin-impregnated collagen fleeces and injectable steroid. The horse returned to a higher level of competitive dressage than prior to surgery. This report describes a large cyst in the distal femur of a horse.     

Development of a 3D model of the equine distal forelimb and of a GRF shoe for noninvasive determination of in vivo tendon and ligament loads and strains

REASONS FOR PERFORMING STUDY: As critical locomotion events (e.g. high-speed and impacts during racing, jump landing) may contribute to tendinopathies, in vivo recording of gaits kinematic and dynamic parameters is essential for 3D reconstruction and analysis. OBJECTIVE: To propose a 3D model of the forelimb and a ground reaction force recording shoe (GRF-S) for noninvasively quantifying tendon and ligament loads and strains. METHODS: Bony segments trajectories of forelimbs placed under a power press were recorded using triads of ultrasonic kinematic markers linked to the bones. Compression cycles (from 500-6000 N) were applied for different hoof orientations. Locations of tendon and ligament insertions were recorded with regard to the triads. The GRF-S recorded GRF over the hoof wall and used four 3-axis force sensors sandwiched between a support shoe and the shoe to be tested. RESULTS: Validation of the model by comparing calculated and measured superficial digital flexor tendon strains, and evaluation of the role of proximal interphalangeal joint in straight sesamoidean ligament and oblique sesamoidean ligament strains, were successfully achieved. Objective comparisons of the 3 components of GRF over the hoof for soft and hard grounds could be recorded, where the s.d. of GRF norm was more important on hard ground at walk and trot. CONCLUSIONS: Soft grounds (sand and rubber) dissipate energy by lowering GRF amplitude and diminish bounces and vibrations at impact. At comparable speed, stance phase was longer on soft sand ground. POTENTIAL RELEVANCE: The conjugate use of the GRF-S and the numerical model would help to quantify and analyse ground/shoe combination on comfort, propulsion efficiency or lameness recovery.     

A laboratory system for production of flexion rates and forces in the forelimb of the horse

The distal portion of the forelimb of the horse is provided with a stay apparatus composed of tendons, ligaments, and fascia. This stay apparatus provides the major resistance to joint flexion during the support phase of the stride. The laboratory test system described was shown to be able to reproduce in vitro limb motions and hoof forces measured with a running horse. These results indicated the stay apparatus operates in a largely passive mode, active muscle contraction apparently serving to provide rigidity only early in the support phase of the stride. The testing system described was designed to take advantage of the passive nature of the stay apparatus in order to study in vitro the forces, accelerations, and deformations encountered by the limb of the galloping horse in vivo.