Horizontal moment around the hoof centre of pressure during walking on right and left circles.

REASONS FOR PERFORMING STUDY: Recent research indicates that the digital joints experience some degree of extrasagittal motion during stance and that the moments under the hoof are asymmetric in horses walking in a straight line. On a circle, these have not been defined. OBJECTIVES: To quantify the amplitude and symmetry of horizontal twisting moments around the vertical axis through the hoof's centre of pressure on left and right circles at walk. METHODS: Six Thoroughbred horses were led at walk across a Kistler force platform on a left and a right circle of 5 m radius. The resultant moment around the hoof was calculated from the 4 horizontal forces and their moment arms. RESULTS: Five of the 6 horses exerted an internal moment around their left forehoof, and 4 exerted an internal moment around their right forehoof on the left circle. On the right circle, 5 of the 6 exerted an internal moment around the left forehoof and a weak external moment around the right forehoof. The moments under the hind hooves were bilaterally similar for right and left circles. CONCLUSION: Intrahorse variability in the applied moments is low, but there is some interhorse variability, especially in the forelimb moments, that indicates future studies of movements of the distal limb joints should be bilateral to account for mechanical asymmetry. POTENTIAL RELEVANCE: The finding that horizontal moments vary between forelimbs in some horses will apply to how exercise on a circle is approached, especially in rehabilitation programmes for horses with orthopaedic injury of the distal limb.

Use of a Collar-Mounted Triaxial Accelerometer to Predict Speed and Gait in Dogs.

Accelerometry has been used to measure treatment efficacy in dogs with osteoarthritis, although interpretation is difficult. Simplification of the output into speed or gait categories could simplify interpretation. We aimed to determine whether collar-mounted accelerometry could estimate the speed and categorise dogs' gait on a treadmill. Eight Huntaway dogs were fitted with a triaxial accelerometer and then recorded using high-speed video on a treadmill at a slow and fast walk, trot, and canter. The accelerometer data (delta-G) was aligned with the video data and records of the treadmill speed and gait. Mixed linear and logistic regression models that included delta-G and a term accounting for the dogs' skeletal sizes were used to predict speed and gait, respectively, from the accelerometer signal. Gait could be categorised (pseudo-R2 = 0.87) into binary categories of walking and faster (trot or canter), but not into the separate faster gaits. The estimation of speed above 3 m/s was inaccurate, though it is not clear whether that inaccuracy was due to the sampling frequency of the particular device, or whether that is an inherent limitation of collar-mounted accelerometers in dogs. Thus, collar-mounted accelerometry can reliably categorise dogs' gaits into two categories, but finer gait descriptions or speed estimates require individual dog modelling and validation. Nonetheless, this accelerometry method could improve the use of accelerometry to detect treatment effects in osteoarthritis by allowing the selection of periods of activity that are most affected by treatment.

Horizontal moment around the hoof's centre of pressure during walking in a straight line.

REASONS FOR PERFORMING STUDY: Joint congruity and ligaments restrain the distal limb joints from excessive motion in the transverse and frontal planes, but the magnitudes and direction of the horizontal twisting moments around the hoof's centre of pressure (CoP) that induce these motions are unknown. OBJECTIVES: To quantify the horizontal moment around the vertical axis through the hoof's CoP at walk, and to determine whether these are symmetric. METHODS: Nine sound Thoroughbred horses (mean age 53 years; mean mass 502 kg) were led at walk in a straight line across a Kistler force platform. Five trials were collected for each fore and hindlimb. The resultant moment around the hoof's CoP was calculated from the horizontal moment arms between the calculated CoP and the 4 horizontal forces in the transverse (X) and cranio-caudal (Y) directions. RESULTS: The calculated moments were consistent within limbs and horses, but variable between horses. Hindlimbs demonstrated a biphasic moment pattern and the largest moments were typically in the first half of stance. Mean +/- s.d. peak moments were internal under both hindlimbs (L: Int 14.1 +/- 4.6 Nm; R: Int 133 +/- 5.5 Nm). In the forelimbs, 7/9 horses demonstrated an asymmetric moment pattern, with the left forelimb exerting an internal moment (L: Int 6.9 +/- 2.9 Nm) and the right forelimb an external moment (R: Ext 8.4 +/- 4.4 Nm), while the remaining 2 horses exerted internal moments in both forelimbs (L: Int 11.7 +/- 1.4 Nm; R:Int 6.6 +/- 1.9 Nm). CONCLUSION: In 7/9 horses, the forelimbs exerted asymmetric horizontal moments around the hoof CoP. The hindlimbs appear to behave with mechanical symmetry during stance, exerting an internal moment during retraction. POTENTIAL RELEVANCE: Extrasagittal joint motions in the forelimb are unlikely to be symmetric and future studies should account for possible bilateral variations.

Can owners and clinicians assess outcome in dogs with fragmented medial coronoid process?

OBJECTIVES: To investigate the long term reliability of clinician and owner visual analogue score (VAS) for dogs with unilateral forelimb lameness attributable to fragmented medial coronoid process (FMCP) when compared to objective gait analysis. METHODS: Nine dogs with unilateral thoracic limb lameness due to FMCP underwent inverse dynamics gait analysis at initial presentation, and at one, two, six and 12 months following diagnosis. Total support moments were calculated and a total support moment ratio (TSMR) derived as an objective assessment of thoracic limb asymmetry. A VAS questionnaire for lameness was completed by the owner of each dog for each visit. Video footage of each dog walking and trotting at each visit was compiled, assigned to random order and subjected to VAS for lameness by a specialist in small animal surgery. Data from owner and clinician VAS lameness questionnaires were compared to the thoracic limb TSMR. RESULTS: Statistical analysis demonstrated a significant negative correlation between TSMR and owner VAS at four weeks post treatment but at no other period of evaluation. There was no significant correlation between TSMR and clinician VAS score at any evaluation period. CLINICAL SIGNIFICANCE: Assessments by owner and clinicians using VAS appear to be of limited use as a long term outcome measure for dogs with unilateral lameness due to FMCP when compared to objective gait analysis. There is a tendency for owners to underestimate forelimb lameness with increasing time which is not supported by quantitative measures of gait.

Are sound dogs mechanically symmetric at trot? No, actually.

A two-year-old, sound Labrador Retriever was determined to be 'right hind limb dominant' by comparison of total hind limb moments of support using inverse dynamics. Net joint moments at the hip, tarsal and meta-tarsophalangeal joints were larger on the right side. Vertical joint reaction forces at the stifle were larger on the right, and horizontal stifle joint reaction forces were smaller on the right. The crus segment was more cranially inclined on the right side through most of stance, but the angle of the resultant stifle joint reaction force vector against the long axis of the crus segment was identical between the right and left sides. The cranially inclined crus segment orientation on one side, coupled with the larger vertical joint reaction force, may result in an internal asymmetry in stifle joint mechanics, although the effects of this on cruciate ligament stresses remain to be determined.

Joint angle, moment and power compensations in dogs with fragmented medial coronoid process.

Fragmented medial coronoid process (FMCP) is the most common cause of forelimb lameness in juvenile medium and large breed dogs; however methods of assessing the disruption to their gait remain subjective. The purpose of this study was to objectively quantify the mechanical disruptions to gait in dogs with arthroscopically confirmed unilateral FMCP. Seven dogs underwent full inverse dynamic analysis at the time of diagnosis. Kinematic and force data were collected from both forelimbs at trot. Stance phase joint angles, net joint moments and net joint powers were calculated using custom software. There were gross differences in kinetic and kinematic patterns between FMCP affected and compensating forelimbs. Stance time was 0.24 sec on the lame side and 0.26 sec on the compensating side. The shoulder and the elbow were more flexed at ground contact, and elbow, carpal and MCP joints had smaller ranges of motion on the lame side. Net joint moments were significantly reduced (P < 0.05) in the elbow, carpal and MCP joints of the FMCP affected limb. Net joint powers were likewise significantly smaller (P < 0.05). However, the overall moment and power patterns persisted. Total limb support moment was significantly smaller on the affected side (P < 0.05). Total limb power was significantly reduced on the affected side (P < 0.05) being most affected in its propulsive phase in the second half of stance. Inverse dynamic analysis of this clinical condition is an objective means by which to assess the mechanical disruption to gait.

Associations between hoof shape and the position of the frontal plane ground reaction force vector in walking horses.

AIMS: To determine the frontal plane position of the ground reaction force vector at its centre of pressure under the hoof of walking horses, and its projection through the distal limb joints, and to relate this to hoof geometric measurements. METHODS: Reflective markers were glued to the forelimb hooves and skin of 26 horses, over palpable landmarks representing centres of the coffin, fetlock and carpal joints, and the dorsal toe at its most distal point. A 4-camera kinematic system recorded the position of these markers as the horse walked in hand across a force platform, to generate a frontal plane representation of the ground reaction force vector passing between the markers at the joints. The position of the vector was calculated as the relative distance between the lateral (0%) and medial (100%) markers at each joint. Digital photos were taken of the hoof in frontal and sagittal views to determine hoof geometric measurements. Associations between these and the position of the force vector at each joint were examined using Pearson correlation coefficients. RESULTS: Mean vector position for both forelimbs at the toe, coffin, fetlock and carpal joint was 50.1 (SD 8.9), 53.0 (SD 9.2), 54.6 (SD 11.4) and 50.5 (SD17.3)%, respectively, of the distance between the lateral and medial sides of the joint in the frontal plane. Across all four joints, the vector position was slightly more medial (2-4%) for the right than left limb (p>0.05). Medial hoof wall angle was correlated (p<0.05) with force vector position at the fetlock (r=-0.402) and carpal (r=-0.317) joints; lateral hoof wall angle with vector position at the toe (r=0.288) and carpal (r=-0.34) joint, and medial hoof wall height with vector position at the fetlock (r=-0.306) and carpal (r=-0.303) joints. CONCLUSION: The position of the two-dimensional frontal plane ground reaction force vector at the toe, and at the fetlock and carpal joints was associated with hoof shape. Mediolateral hoof balance has been shown in vitro to affect articular forces, which may be a factor in development of joint disease. The effect of hoof shape needs to be evaluated at faster gaits to determine the potential for joint injury in the presence of larger forces.

Joint angle feedback and biomechanical gait analysis in stroke patients: a case report.

The purpose of this case report is to demonstrate the use of gait analysis and computer-assisted visual and auditory feedback (CAF) in the treatment of a patient with stroke secondary to hemiplegia. Two-dimensional kinematic and kinetic gait analyses were performed to determine the objectives of treatment and to evaluate the results. The CAF hardware and software permitted immediate visual feedback of performance relative to the desired target with auditory reinforcement if the target was reached in the desired phase of the gait cycle. The objective of the treatment was to increase knee flexion during push-off and pull-off. After four weekly treatments, the patient's gait velocity and stride length, in addition to transfers between kinetic energy and potential energy, were significantly improved. The patient demonstrated a downward trend in total mechanical energy costs and an upward trend in the amount of energy conservation, as well as increased knee flexion. These promising results indicate a need for further research into the use of CAF as a tool in motor learning for rehabilitation.

The hindlimb in walking horses: 2. Net joint moments and joint powers.

The objective of the study was to describe net joint moments and joint powers in the equine hindlimb during walking. The subjects were 5 sound horses. Kinematic and force data were collected synchronously and combined with morphometric information to determine net joint moments at each hindlimb joint throughout stance and swing. The results showed that the net joint moment was on the caudal/plantar side of all hindlimb joints at the start of stance when the limb was being actively retracted. It moved to the cranial/dorsal side around 24% stride at the hip and stifle and in terminal stance at the more distal joints. It remained on the cranial/dorsal side of all joints during the first half of swing to provide active limb protraction, then moved to the caudal/plantar aspect to reverse the direction of limb motion prior to ground contact. The hip joint was the main source of energy generation throughout the stride. It was assisted by the tarsal joint in both stance and swing phases and by the fetlock joint during the stance phase. The coffin joint acted as an energy damper during stance, whereas the stifle joint absorbed almost equal amounts of energy in the stance and swing phases. The coffin and fetlock joints absorbed energy as the limb was protracted and retracted during the swing phase, suggesting that their movements were driven by inertial forces. Future studies will apply these findings to detect changes in the energy profiles due to specific soft tissue injuries.

Net joint moments and powers in the equine forelimb during the stance phase of the trot.

The objective of this study was to provide normative data describing the net joint moments and joint powers for the stance phase of the forelimb in trotting horses. Kinematic and force plate data, synchronised in time and space, were collected for the right forelimb of 6 Warmblood horses moving at a trot. The 3-D kinematic data were collapsed onto a sagittal plane, and were combined with the vertical and longitudinal ground reaction forces and with segment morphometric data to calculate net joint moments in the sagittal plane across the distal interphalangeal (coffin), metacarpophalangeal (fetlock), carpal, elbow and shoulder joints. The joint mechanical power was calculated as the product of the joint moment and the joint's angular velocity. Major peaks on the moment and power curves were identified. Each joint showed consistent and repeatable patterns in the net joint moments and joint powers. During most of stance the net joint moment was on the caudal/palmar side of all joints except the shoulder. At the coffin joint the power profile indicated an energy absorbing function that peaked at 74% stance, which coincided with the maximal longitudinal propulsive force. The fetlock joint behaved as an elastic spring; energy was absorbed in the first half of stance as the flexor tendons and SL stored elastic energy, which was released in the second half of stance as a result of elastic recoil. The carpus did not appear to play an important role in energy absorption or propulsion. Both the elbow and shoulder joints showed what appeared to be phases of elastic energy storage and release in the middle part of the stance phase, followed by a propulsive function at the shoulder in the later part of stance. The fetlock, carpus and elbow showed virtually no net generation or absorption of energy. The net energy generation at the shoulder joint was approximately equal to the energy absorption at the coffin joint. In human subjects specific gait pathologies produce characteristic alterations in the shape of the power profile as well as changes in the amount of energy absorbed and generated at the joints. In horses evaluation of net joint moments and joint powers will further our understanding of the mechanics and energetics of lameness, and may prove to be a useful diagnostic tool. An understanding of the function and dysfunction of different anatomical structures will facilitate the interpretation of clinical findings in terms of mechanical deficits.

Kinematics and ground reaction forces in horses with superficial digital flexor tendinitis.

OBJECTIVE: To measure and correlate kinematic and ground reaction force (GRF) data in horses with superficial digital flexor tendinitis. ANIMALS: 6 sound horses. PROCEDURE: Horses were evaluated before (sound evaluation) and after (lame evaluation) induction of superficial digital flexor tendinitis in 1 forelimb (randomized) by injection of collagenase. As each horse trotted, kinematic data were collected by use of an optoelectronic system, and GRF data were measured by use of a force plate. Three-dimensional kinematic and GRF data were projected onto a 2-dimensional sagittal plane. RESULTS: Lame limbs had significantly lower peak vertical GRF, less flexion of the distal interphalangeal joint, and less extension of the metacarpophalangeal joint, compared with compensating limbs. Carpal joint kinematics did not change. Compensating limbs had a more protracted orientation throughout the stance phase and higher braking longitudinal force and impulse; however, total range of rotation from ground contact to lift off did not change. Transfer of body weight from lame to compensating limbs was smooth, without elevation of the body mass into a suspension phase. Propulsive components of longitudinal GRF did not differ between limbs. CONCLUSIONS AND CLINICAL RELEVANCE: In horses with experimentally induced superficial digital flexor tendinitis, changes in vertical GRF were reflected in angular excursions of the distal interphalangeal and metacarpophalangeal joints, whereas changes in longitudinal GRF were associated with alterations in the protraction-retraction angle of the entire limb.

Net joint moments and joint powers in horses with superficial digital flexor tendinitis.

OBJECTIVE: To determine whether analysis of net joint moments and joint powers is a suitable technique for evaluation of mechanics and energetics of lameness in horses and to measure effects of superficial digital flexor tendinitis. ANIMALS: 6 sound horses. PROCEDURE: Horses were evaluated before (sound evaluation) and after (lame evaluation) induction of superficial digital flexor tendinitis in 1 forelimb by injection of collagenase. Recordings were made with an optoelectronic system and a force plate as horses trotted. Net joint moments and joint powers in the sagittal plane at each joint in the forelimbs during the stance phase were determined. Peak values were determined, and mechanical energy absorbed and generated at each joint was calculated. Comparisons were made between contralateral limbs during sound and lame evaluations. RESULTS: Lame limbs had significant reductions in peak values for net joint moments on the palmar aspect of metacarpophalangeal (fetlock), carpal, and humeroulnar joints. Total energy absorbed was significantly lower at every joint in lame limbs, compared with compensating limbs. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with superficial digital flexor tendinitis had significant differences between lame and compensating limbs for net joint moments and joint powers at all joints, indicating that the gait of horses with superficial digital flexor tendinitis is energetically inefficient. Assessment of net joint moments and joint powers is a useful tool in evaluating equine lameness.

Forelimb joint moments and power during the walking stance phase of horses.

OBJECTIVE: To calculate normative joint moments of force and power for the forelimb of walking horses as a benchmark against which to compare these mechanical variables in horses with specific lameness. ANIMALS: 4 Dutch Warmblood horses with no recent history of lameness. PROCEDURE: Horses were walked by hand through the test area, and data from 5 walking trials were collected for each horse. Two camera views were combined with vertical and craniocaudal ground reaction forces to calculate net moments of force in the sagittal plane across the carpal, metacarpophalangeal (fetlock), and distal interphalangeal (coffin) joints during the stance phase of the forelimb. Mechanical power was calculated as the product of net joint moment and the joint's angular velocity. RESULTS: During the early part of the stance phase, the carpal joint had oscillating periods of energy generation and absorption against a predominant flexor moment, then an absorption phase at the end of the stance phase, as the carpus flexed into swing against an extensor moment. The fetlock absorbed energy in the early part of the stance phase, then the terminal part was marked by a large generation of energy across the joint. A flexor moment was measured at the coffin joint throughout the stance phase, and this coincided with a long phase of energy absorption followed by a short phase of generation for push-off. CONCLUSION: Consistency of the power data indicates that typical profiles of work exist for each of the joints (carpus, fetlock, and coffin). CLINICAL RELEVANCE: Detection of changes to these profiles of work may contribute to diagnosis of specific lameness conditions.

Total knee replacement in a dog with a non-union type B3 tibial plateau fracture.

A six-year-old German Shorthaired Pointer was presented with a 12 month history of left pelvic limb lameness following trauma. Clinical examination revealed marked thickening and reduced range-of-motion of the left stifle and radiographs were suggestive of a non-union type B3 tibial plateau fracture with severe secondary osteoarthritis. Total knee replacement was performed with adjunctive stabilization of the proximal tibial fracture fragment. Clinical follow-up at six and 12 months with quantitative gait analysis revealed significant improvement in limb function.

A novel method for defining the Greyhound talocrural joint axis of rotation for hinged transarticular external skeletal fixation.

In order to apply hinged transarticular external skeletal fixation for stabilization of the injured canine tarsal joint, knowledge of the three-dimensional (3D) location and orientation of the transverse axis is necessary. This method of immobilization may be used as a primary or adjunctive method of stabilisation for a large number of traumatic conditions. Using pin-mounted markers in the cadaveric Greyhound crus and talus, a closed-form solution of absolute orientation was used to identify, on radiographs, the lateral and medial locations of the transverse axis by tracking the 3D excursions of the markers during flexion and extension. A line was drawn across the dorsal aspect of the calcaneus from the most dorsal point on the distal articular surface(proximal intertarsal joint: PIJ) to the most dorsal point on its proximal articulation with the body of the talus, and the location of the centre of rotation was expressed in terms of the length of that line. In seven Greyhound tarsal joints, the medial end of the axis was located 73 ± 10% proximal to the PIJ and 11 ± 7% dorsal to the line. The lateral end was 73 ± 9% proximal tothe PIJ and -2 ± 3% plantar to the line.

Lame broiler chickens respond to non-steroidal anti-inflammatory drugs with objective changes in gait function: a controlled clinical trial.

Leg health of intensively reared broiler chickens is a significant problem, yet little is known regarding the nature of lameness-associated pain. Kinematic changes in gait have been reported in naturally lame broilers following subcutaneous non-steroidal anti-inflammatory drug (NSAID) administration, compared to a placebo group. In the current study, an extensive range of gait parameters were defined using a commercial motion-capturing system to record three-dimensional temporospatial information from walking broilers pre- and post-treatment. Data analysis, performed using multi-level models, revealed gait modifications in broilers receiving NSAID, but not in those receiving saline. The effect of walking velocity was accounted for retrospectively. An increase in velocity following NSAID treatment (carprofen: P<0.001; meloxicam: P=0.044) indicated improved walking ability. For several measures, the polarity of the treatment effect depended upon walking speed. At slow speeds certain parameters become more like those of non-lame broilers, which may have been indicative of improved stability: stride length and duration (both NSAIDs), transverse back displacement (meloxicam), and vertical leg displacement (carprofen). However, these same parameters also revealed that NSAID treatment caused imbalance at faster speeds, which may have signified an excessive dosage. Although doses employed were not conclusively effective, evidence was provided that factors besides body conformation influenced mobility in the test cohort. The study showed that the model would be useful in future studies to increase our understanding of pain associated with specific lameness types in broiler chickens.

An ex vivo investigation of the effect of the TATE canine elbow arthroplasty system on kinematics of the elbow.

OBJECTIVE: To devise a kinematic technique to objectively ascertain the location and orientation of the centre of rotation of the canine elbow and to compare this axis following arthroplasty with the first generation TATE™ prosthesis in an ex vivo model. METHODS: Five pairs of cadaveric forelimbs were obtained and proximal limb soft tissues removed. Pin-mounted reflective markers were applied to the humerus and ulna. Limbs were mounted on a frame and six trials of the elbow manually cycled through its sagittal range of motion captured using 4 Qualisys cameras at 120 Hz. Radiography was performed to identify marker position. TATE™ cartridges were implanted and kinematic analysis repeated. Kinematic data were imported into custom software and the three-dimensional joint centre of rotation defined using a closed-form solution for absolute orientation. Paired t tests were performed to determine if the centre of rotation of the elbow differed significantly (P<0·05) pre- and postoperatively and between left and right limbs. RESULTS: There was no significant difference in three-dimensional orientation of the elbow axis between pre and postoperative measurements or between left and right limbs. CLINICAL SIGNIFICANCE: A critical factor in obtaining a successful functional outcome following elbow arthroplasty in humans is accurate reconstruction of the anatomic centre of rotation. The first generation TATE canine elbow arthroplasty cartridge and its instrumentation accurately reconstructed the anatomic centre of rotation in 8 of the 10 elbows assessed in this ex vivo model.

Rehabilitation of an electrical burn patient through thermal biofeedback.

A 22-year-old male subject, with high-voltage electrical burns to one wrist, utilized differential relaxation and visual biofeedback to increase skin temperature in the damaged hand. Through 14 thermal biofeedback and passive relaxation sessions, the subject was able to produce temperature increases in his damaged hand of up to 21 degrees F, which considerably diminished the pain. Healing, feeling, and movement control seemed to progress with extreme rapidity, suggesting that axoplasmic transport was greatly enhanced.