Accuracy of asymmetry indices of ground reaction forces for diagnosis of hind limb lameness in dogs

OBJECTIVE: To determine the accuracy of asymmetry indices of ground reaction forces (GRF) for diagnosis of hind limb lameness in dogs. ANIMALS: 36 healthy dogs and 13 dogs with naturally acquired cranial cruciate ligament rupture or hip dysplasia. PROCEDURES: Lameness for affected dogs ranged from not detectable to minor and constant. While dogs trotted on an instrumented treadmill, GRF variables were recorded and analyzed with asymmetry indices. Each index was tested for its ability to discriminate between healthy and affected dogs. Combinations of several indices were also assessed. RESULTS: Vertical force variables had better accuracy than craniocaudal force variables. Peak vertical force was the most accurate variable. Partial asymmetry during trotting was detected in healthy dogs. A multivariate approach that used peak vertical force and maximal rising slope yielded the optimum combination to distinguish between healthy and affected dogs. In addition, sensitivity of 92% or specificity of 95% may be achieved with 2 cutoff values while simultaneously maintaining specificity or sensitivity, respectively, at > 85%. CONCLUSIONS AND CLINICAL RELEVANCE: Asymmetry indices of GRFs were accurate for detection of hind limb lameness in dogs. This is particularly relevant for study designs in which only a single gait evaluation is possible.     

Force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness.

OBJECTIVE: To evaluate the accuracy of force plate gait analysis at the walk and trot in dogs with low-grade hindlimb lameness. MATERIAL AND METHODS: Nineteen healthy dogs and 41 dogs with low-grade unilateral hindlimb lameness due to stifle or hip joint problems were walked and trotted over a force plate. Peak vertical forces (PVF) were recorded, and a symmetry index (SI) was calculated from the PVF of the hindlimbs. 'Cut-off' values were determined from the SI of the normal dogs. These cut-off values were used to discriminate lame dogs from normal ones. Sensitivity and specificity were evaluated for measurements at walk and trot, and the Cohen's Kappa coefficient (k) was used to determine the agreement between clinical lameness and force plate measurements, and between force plate results at walk and trot. Receiver Operating Characteristics (ROC) curve were plotted for both gaits to evaluate accuracy. RESULTS: The sensitivity of the measurements at walk was 0.63, and specifity was 0.95. The sensitivity of the measurements at trot was 0.90, and specificity was 1.0. Moderate agreement was found between force plate measurements at walk and trot, and between clinical gait assessment and force plate measurements at walk. Good agreement was found between clinical gait assessment and measurements at trot. ROC analyses revealed the trot (94.7% [91.7%; 97.7%]) to be the more accurate test than the walk (85.0% [80.1%; 89.9%]). CONCLUSION: The trotting gait was more sensitive and accurate than the walking gait for the differentiation of dogs with a low-grade hindlimb lameness from normal ones using force plate gait analysis.     

Accuracy and optimization of force platform gait analysis in Labradors with cranial cruciate disease evaluated at a walking gait

OBJECTIVE: To determine the combination of ground reaction forces (GRFs) that best discriminates between lame and non-lame dogs. To compare the sensitivity of force platform gait analysis and visual observation at detecting gait abnormalities in Labradors after surgery for rupture of the cranial cruciate ligament (CCL). ANIMALS: All dogs were adult Labrador Retrievers: 17 free of orthopedic and neurologic abnormalities, 100 with unilateral CCL rupture, and 131 studied 6 months after surgery for unilateral CCL injury, 15 with observable lameness. PROCEDURE: Dogs were walked over a force platform with GRF recorded during the stance phase. Analytic properties of force platform gait analysis were calculated for several combinations of forces. The probability of visual observation detecting a gait abnormality was compared with that of force platform gait analysis. RESULTS: We determined that a combination of peak vertical force (PVF) and falling slope were optimal for discriminating sound and lame Labradors. After surgery, many dogs (75%) with no observable lameness failed to achieve GRFs consistent with sound Labradors. CONCLUSION: A force platform is an accurate method of assessing lameness in Labradors with CCL rupture and is more sensitive than visual observation. Assessing lameness with a combination of GRFs is better than using univariate GRFs. CLINICAL RELEVANCE: Therapies for stifle lameness can be accurately and objectively evaluated using 2 vertical ground reaction forces obtained from a force platform.     

Kinetic gait and subjective analysis of the effects of a tachykinin receptor antagonist in dogs with sodium urate-induced synovitis

OBJECTIVE: To examine the ability of preemptive administration of a proprietary neurokinin-1 (NK(1)) receptor antagonist to attenuate limb dysfunction associated with monosodium urate-induced synovitis in the stifle joints of dogs. ANIMALS: 16 clinically normal adult mixed-breed dogs (8 males and 8 females). PROCEDURES: A crossover study was conducted in 2 phases. Dogs were assigned to 2 groups (8 dogs/group) and orally administered an NK(1) receptor antagonist (3 mg/kg) or a control substance once daily for 4 days. Synovitis was then induced in the left stifle joint by intra-articular injection of monosodium urate. Investigators were not aware of treatment group assignments. Dogs were evaluated by use of subjective lameness scores during standing, walking, and trotting and by use of ground reaction force data 3, 6, 9, 12, and 24 hours after urate injection. After a 21-day washout period, the experiment was repeated with each dog administered the other treatment and injected with monosodium urate in the contralateral stifle joint. RESULTS: No significant differences were detected between the NK(1) receptor antagonist and control treatments with regard to peak vertical force, vertical impulse area, or subjective evaluations of lameness during standing, walking, or trotting, except during walking 24 hours after monosodium urate injection. CONCLUSIONS AND CLINICAL RELEVANCE: Preemptive administration of an NK(1) receptor antagonist failed to significantly improve subjective or objective outcome measures in dogs with monosodium urate-induced synovitis.     

Evaluation of a pressure walkway system for measurement of vertical limb forces in clinically normal dogs

OBJECTIVE: To compare ground reaction forces (GRFs) measured by use of a pressure-sensitive walk-way (PSW) and a force plate (FP) and evaluate weekly variation in the GRFs and static vertical forces in dogs. ANIMALS: 34 clinically normal dogs and 5 research dogs with lameness. PROCEDURE: GRF data were collected from 5 lame and 14 clinically normal dogs by use of an FP and a PSW. Peak vertical force (PVF), vertical impulse (VI), and velocity measurements (determined by use of photocells and PSW data) were compared between groups. Peak vertical force, VI, stride length, ground phase time (ie, contact time), and static body weight distribution data were collected on 2 occasions, 1 week apart, in 20 different clinically normal dogs by use of a PSW; week-to-week variation in values was evaluated. RESULTS: Measurements of velocity derived by use of the photocells were not different from those derived by use of the PSW. For any 1 limb, values derived by use of the PSW were significantly lower than values derived with the FP. For values obtained by use of either technique, there were no differences between left and right limbs except for values of PVF measured via PSW in forelimbs. Values of PVF, VI, contact time, stride length, and static weight distribution generated by the PSW did not vary from week to week. CONCLUSIONS AND CLINICAL RELEVANCE: Values for GRFs varied between the FP and PSW. However, data derived by use of PSW were consistent and could be used to evaluate kinetic variables over time in the same dog.     

Relationships of Body Weight,Body Size,Subject Velocity,and Vertical Ground Reaction Forces in Trotting Dogs

Objective: To evaluate the relationship of body weight (BW) and size, dog velocity, and vertical ground reaction forces (GRF) from a large number of dogs of various sizes. Study Design: Clinical research. Animals: Orthopedically healthy dogs (n=129) Methods: BW and dog size, represented as height at the withers (WH), were obtained. Stance times (ST), vertical impulses (VI), and peak vertical forces (PVF) of thoracic and pelvic limbs were measured on a force plate at controlled trotting speed. They were evaluated against BW and WH using linear regression analysis in absolute (nonnormalized) values, and when normalized to BW and/or body size according to the theory of dynamic similarity. Relative velocities were calculated for each dog. Results: Absolute ST, VI, and PVF showed strong positive correlations with BW and/or body size. When GRFs were normalized to BW, correlations with body size were markedly reduced, but remained positive for VI, and turned negative for PVF. Normalizing the time‐dependent variables (ST and VI) also to WH eliminated most size influence. A small dependency of fully normalized GRF on body size remained that was because of differences in relative velocity between dogs of different sizes. Reference values for the fully normalized data are given. Conclusions: The inherent relationship between BW, body size, dog velocity, and vertical GRF was demonstrated. Clinical Relevance: BW, body size, and relative dog velocity must be accounted for when wanting to obtain GRF variables that are comparable between different dogs.     

Evaluation of pentosan polysulfate sodium in the postoperative recovery from cranial cruciate injury in dogs: a randomized, placebo-controlled clinical trial

OBJECTIVE: To evaluate the efficacy of pentosan polysulfate (PPS) for improving the recovery period and mitigate the progression of osteoarthritis (OA) of the canine stifle after extracapsular stabilization of cranial cruciate ligament (CCL) injuries. STUDY DESIGN: Randomized, blinded, placebo-controlled clinical trial. ANIMALS: Dogs (n=40) with unilateral CCL instability. METHODS: Each dog had an extracapsular stabilization of the stifle with or without partial meniscectomy. Dogs were divided into 4 groups based on preoperative radiographic assessment and whether a partial meniscectomy was performed. Dogs were randomly assigned to either (3 mg/kg) PPS or placebo treatment in each group, and then injected subcutaneously weekly for 4 weeks. Lameness, radiographic changes, biological marker concentration in blood and urine, and ground reaction forces (GRFs) were collected preoperatively, and at 6, 12, 24, and 48 weeks. Data were analyzed within and between groups using repeated measures ANOVA; P<.05 was considered significant. RESULTS: No adverse reactions to PPS were reported. Thirty-nine dogs completed a minimum of 24-weeks follow-up and 33 dogs completed 48 weeks. All dogs clinically improved after surgery without differences in lameness score, vertical GRFs, or radiographic progression. Grouped and evaluated only by initial radiographic score, PPS-treated dogs improved significantly faster in braking GRFs than placebo-treated dogs. In dogs with partial meniscectomies, urine deoxypyridinoline, and serum carboxy-propeptide of type II collagen were significantly increased at 6 weeks in placebo-treated dogs compared with PPS-treated dogs. CONCLUSIONS: PPS administered after stabilization of the cruciate deficient stifle may prove to be a useful adjunctive treatment option, although further studies are necessary to substantiate this claim.     

Compensatory load redistribution in naturally occurring osteoarthritis of the elbow joint and induced weight-bearing lameness of the forelimbs compared with clinically sound dogs

The current study investigated the compensatory load redistribution due to osteoarthritis of the elbow joint using ground reaction forces of all four legs, simultaneously measured on a treadmill with integrated force plates. Three groups of dogs were used: the first group was clinically sound; the second group suffered from a naturally occurring osteoarthritis of the elbow joint, and a reversible lameness was induced in the third group. The naturally occurring osteoarthritis resulted in a compensatory gait pattern to reduce the stress on the affected limb. The load was reduced on the lame limb and increased on the contralateral hindlimb. The symmetry index indicated a weight-shift to the contralateral forelimb and diagonal hindlimb, which resulted in a more balanced weight distribution than in normal dogs. Dogs with induced lameness showed comparable but less pronounced alterations. These results suggested that forelimb lameness could lead to overload on non-affected extremities and the vertebral spine.     

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.     

Vertical Frontlimb Ground Reaction Forces of Sound and Lame Warmbloods Differ From Those in Quarter Horses

Lameness is a highly prevalent condition in horses and is the principal cause of removal from athletic activity in this species. In evidence-based veterinary medicine studies to evaluate non-setoidal anti-inflammatory drug (NSAID) therapies, force plates are commonly used to objectively assess improvement of lameness. The objective of this study was to determine whether breed differences would influence force plate measurements in sound and lame riding horses. Force plate measurements of lame (n = 20) and sound (n = 18) Warmblood and lame (n = 15) and sound (n = 8) Quarter Horses were compared. Lameness was visually scored using the grade 0–5 American Association of Equine Practitioners (AAEP) lameness scale. Trotting sound Warmbloods loaded their frontlimbs with 118% body weight (BW) and their hindlimbs with 96% BW, whereas Quarter Horses only used 101% BW in the front and 92% BW in the hindlimbs (P < .05). Furthermore, it appeared and was estimated that, at trot, front-limb-lame Warmblood horses showed higher peak vertical force (PVF) values (grade 2: 89% BW; grade 3: 69% BW), than front-limb-lame Quarter Horses with similar lameness scores (grade 2: 78% BW; grade 3: 66% BW). In conclusion, peak vertical forces (PVF expressed in % BW) of either lame or sound horses seem to be influenced by breed differences between Warmblood and Quarter Horse riding horses. Possible conformation and gait differences enabled trotting Quarter Horses to demonstrate lower absolute PVF values than Warmbloods, whereas trotting lame Warmbloods showed a relatively larger decrease in frontlimb loading and thus in PVF than lame Quarter Horses at a trot. Thus, in studies in which objective lameness observations are recorded, breed differences should be taken into account when specific grades of lameness of a group of horses are to be objectively compared with another group.     

Measurement of vertical forces and temporal components of the strides of horses using instrumented shoes

Instrumented shoes were used to measure the vertical forces exerted by horses moving at a variety of gaits. Two types of shoes were used; one contained a single transducer positioned over the center of the frog and the second contained transducers located at the toe and both sides of the heel. Horses were shod with these instrumented shoes and walked and trotted over a force plate. Forces were simultaneously recorded from the transducers in the shoes and from the force plate. Comparisons were made between the amount and duration of the forces exerted on the transducers and the vertical and horizontal forces recorded from the force plate. Forces recorded from the single transducer shoes showed strong correlations with the forces recorded from the force plate for horses moving at the walk; however, at the trot only moderate correlations occurred between these forces. At both the walk and trot, forces recorded from each side of the heel and the total forces occurring on all three transducers from the front hooves of horses shod with three transducer shoes showed strong correlations to the vertical forces recorded from the force plate.Vertical forces were also recorded from the instrumented shoes as horses walked, trotted and galloped on a track straightaway. Forces recorded from normal horses shod with single transducer shoes on all four feet were greater on the forelimbs than the rear limbs at the walk and trot. At the gallop, forces were highest on the lead front followed by the nonlead front, lead rear and nonlead rearlimb, respectively. Forces recorded from a three transducer shoe on the right front hoof of a horse walking, trotting and galloping in a right lead were highest on the medial side of the heel and occurred during the middle of the support period. Peak forces on the toe occurred at or near the time of heel lift.The results of these studies indicate that these instrumented shoes have advantages over the methods previously used to measure locomotor forces. These instrumented shoes can be used to simultaneously record the temporal components and the amount and distribution of vertical forces exerted during consecutive strides of horses moving at a variety of gaits.     

A comparison of uniaxial and triaxial accelerometers for the assessment of physical activity in dogs

The present study compares the outputs of uniaxial accelerometer (UA) and triaxial accelerometer (TA) to determine whether UAs can be used instead of TAs in estimating physical activity (PA) in domestic dogs (N = 79). The PA of the dogs was measured simultaneously by a UA and a TA attached to regular collars under 3 different conditions: unstructured activity in the kennels (kennel activity); and 2 structured on-lead activities of different intensities on a designated pathway (walking and trotting). The study finds that UA consistently detected significantly more steps. Kennel activity showed the largest differences between the accelerometers, and trotting showed the least. Dogs in the heaviest body weight category showed the best correlation between the devices and the least differences between the accelerometers across the 3 activities. The limits of agreement were wide in all activities. Significantly higher agreements were associated with lower step counts in kennel activity and higher step counts in walking and trotting. The results show that these 2 types of accelerometers cannot be used interchangeably. Confounding factors, such as body weight, must be considered in future analysis of accelerometer outputs and selection of devices for different contexts. Optimal interpretation of objectively measured PA is paramount in supporting future dog fitness, health, and welfare studies.     

Influence of rider on lameness in trotting horses

REASONS FOR PERFORMING STUDY: Equine lameness is commonly evaluated when the horse is being ridden, but the influence of the rider on the lameness has not been documented. OBJECTIVE: To document the effect of 2 riders of different training levels on the vertical movement of the head and croup. METHODS: Twenty mature horses were ridden at trot by an experienced dressage rider and a novice rider, as well as trotted in hand. Kinematic measurements of markers placed on the horse's head and sacral bone were carried out. The asymmetries of the vertical head and sacral bone motion were calculated as lameness parameters and compared with paired t tests. RESULTS: Trotting in hand, 17 horses showed forelimb lameness (1-4/10) and 13 hindlimb lameness (1-2/10). Intra-individually, 11 horses showed significant differences in forelimb lameness and 4 horses showed significant differences in hindlimb lameness when ridden. Over all horses, hindlimb lameness increased significantly under the dressage rider compared to unridden horses. CONCLUSIONS: The presence of a rider can alter the degree of lameness; however, its influence cannot be predicted for an individual horse. POTENTIAL RELEVANCE: In order to evaluate mild lameness, horses should be evaluated at trot both under saddle and in hand. If lameness is exacerbated, a second rider may be helpful; the level of training of the rider should be taken into consideration.     

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 5. Kinematic effects

AIM: To examine the effect of race training on kinematic parameters of the trot in a sample of 2-year-old Thoroughbred fillies. METHODS: Two-year-old Thoroughbred fillies that had been either trained for racing (n=7) or left untrained in small paddocks (n=7) were examined for lameness, and linear and temporal kinematic data were collected from video recordings of each horse trotted in-hand, 5, 9 and 13 weeks after the beginning of training. Horses were graded as: sound (Grade 0), suspected but not obviously lame (Grade 1), or definitely lame at the trot (Grade 2). RESULTS: Mean velocity at the trot did not vary with lameness grade. Compared with horses classified as sound (Grade 0), horses classified as suspected or definitely lame (Grades 1 and 2) had shorter (2.55 (SE 0.02) vs 2.41 (SE 0.02) and 2.44 (SE 0.03) m; p<0.001) and faster (671 (SE 3) vs 645 (SE 1) and 647 (SE 4) msec; p<0.001) strides. None of the linear or temporal parameters measured varied significantly between the successive observation periods. When data from sound horses were pooled, the training group trotted at a higher mean velocity (4.22 (SE 0.08) vs 3.22 (SE 0.06) m/sec; p<0.001) and with a longer stride length (2.79 (SE 0.05) vs 2.18 (SE 0.06) m; p<0.001) than the untrained group. The stride duration was longer (669 (SE 7) vs 662 (SE 9) msec; p=0.01), stance period was shorter (34.1 (SE 0.6) vs 39.3 (SE 0.7) %; p<0.001) and mid-stance was achieved earlier in the stride (12.1 (SE 0.6) vs 13.1 (SE 0.2) %; p=0.001) in the trained than the untrained group. A longer swing phase in the trained group was associated with an increase in retraction time (9.2 (SE 0.2) vs 7.6 (SE 0.3) %; p=0.001). CONCLUSIONS: These data indicate that early race training in young Thoroughbreds was associated with quantifiable changes in linear and temporal kinematic parameters of the trot, which were related to the race-training objective of improving the horse's ability to work at higher velocities. CLINICAL RELEVANCE: Race training resulted in changes in the gait of non-lame horses at the trot, which should be considered during veterinary lameness examinations.     

What can we learn from visual and objective assessment of non-lame and lame horses in straight lines,on the lunge and ridden?

Traditionally and when using objective gait analysis, horses with and without lameness are most frequently assessed trotting in straight lines in hand. Valuable information can be gained from assessment on the lunge and ridden in walk, trot and canter. No studies have quantified lameness during all aforementioned conditions and gaits at once, despite the rapid recent development in equine gait analysis methods. Objective methodologies, previously confined to gait laboratories, are currently being expanded to field technologies using accelerometers and inertial measurement units (IMUs). This publication aims to describe normal gait and the spectrum of pain-related gait abnormalities and other musculoskeletal adaptations to pain that can be observed in walk, trot and canter during in hand and ridden assessment in straight lines and on a circle on hard and soft surfaces. In addition, it aims to describe briefly how IMUs have been used and areas for further research in the light of what we know from subjective lameness examinations and what is possible with IMUs.     

Body centre of mass movement in the sound horse

The body centre of mass (BCM) is a key factor in the analysis of equine locomotion, as its position and movement determines the distribution and magnitude of loads on the limbs. In this study, the three-dimensional (3D) movement of the BCM in walking and trotting horses was assessed using a kinematic, segmental method. Thirty markers representing 20 body segments were recorded in 12 sound horses while standing, walking and trotting on a treadmill using a high-speed video system. Based on segmental inertial data, 3D positions of the segmental centres of mass as well as the total BCM were calculated. The position within the trunk during square standing and the movements of the BCM were determined for the three planes.The position of the BCM in the standing horse is presented relative to external reference points. At the trot, vertical displacement amplitude of the BCM amounted to 53 (6) mm as mean (sd), which was 27% smaller than external trunk movement. Medio-lateral displacement amplitude of the BCM was 19 (4) mm, 34% less than trunk amplitude. Sagittal forward-backward oscillations of the BCM independent from general forward movement were 13 (3) mm, being 24% less than trunk movements. At the walk, vertical, medio-lateral and sagittal BCM movements were smaller than trunk movements by 43, 65 and 65% respectively.The results show reduced and efficient BCM movements compared to the trunk and form a basis for the assessment of various clinical conditions such as lameness, the influence of a rider and various dressage performances.     

Effect of weight reduction on clinical signs of lameness in dogs with hip osteoarthritis

OBJECTIVE: To determine the effect of weight reduction on clinical signs of lameness among overweight dogs with clinical and radiographic signs of hip osteoarthritis. DESIGN: Nonblinded prospective clinical trial. ANIMALS: 9 client-owned dogs with radiographic signs of hip osteoarthritis that weighed 11 to 12% greater than their ideal body weight and were examined because of hind limb lameness. PROCEDURE: Dogs were weighed, and baseline body condition, hind limb lameness, and hip function scores were assigned. Severity of lameness was scored using a numerical rating scale and a visual analogue scale. Dogs were fed a restricted-calorie diet, with amount of diet fed calculated to provide 60% of the calories needed to maintain the dogs' current weights. Evaluations were repeated midway through and at the end of the weight-loss period. RESULTS: Dogs lost between 11 and 18% of initial body weight. Body weight, body condition score, and severity of hind limb lameness were all significantly decreased at the end of the weight-loss period. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in overweight dogs with hind limb lameness secondary to hip osteoarthritis, weight reduction alone may result in a substantial improvement in clinical lameness.     

The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion

REASONS FOR PERFORMING STUDY: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. OBJECTIVES: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. RESULTS: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2 degrees at walk and increased by 3.3 degrees at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9 degrees at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7degrees at T13, 0.8 degres at T17, 0.5 degres at L1, 0.4 degrees at L3 and 0.3 degrees at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3 degrees at T10 and 0.9 degrees at T13) (P<0.05) during stance of the lame diagonal. CONCLUSIONS: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. POTENTIAL RELEVANCE: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness.     

Kinematic analysis in healthy and hip-dysplastic German Shepherd dogs

This study investigated kinematic patterns in clinically normal German Shepherd dogs (GSDs) compared to those with hip dysplasia and with no clinical signs of lameness. Two groups of GSDs, including 10 clinically healthy dogs (G1) and 10 with hip dysplasia (G2), were trotted on a treadmill at a constant speed. Kinematic data were collected by a 3-camera system and analysed by a motion-analysis program. Flexion and extension joint angles and angular velocities were determined for the shoulder, elbow, carpal, hip, stifle, and tarsal joints.Within each group, the differences between the right and left limbs in all kinematic variables were not significant. Minimum angle, angular displacement and minimum angular velocity did not differ between groups. Significant differences were observed in the maximum angular velocity and maximum angle of the hip joint (dysplastic > healthy), and in the maximum angular velocity of the carpal joint (healthy > dysplastic). It was concluded that, when trotting on a treadmill, dysplastic dogs with no signs of lameness may present joint kinematic alterations in the hind as well as the forelimbs.     

The effect of induced hindlimb lameness on thoracolumbar kinematics during treadmill locomotion

REASON FOR PERFORMING STUDY: There are no detailed studies describing a relationship between hindlimb lameness and altered motion of the back. OBJECTIVES: To quantify the effect of induced subtle hindlimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses were measured during walk and trot on a treadmill before and during application of pressure on the sole of the left hindlimb using a well-established sole pressure model. Reflective markers were located at anatomical landmarks on the limbs, back, head and neck for kinematic recordings. Ground reaction forces (GRF) in individual limbs were calculated from kinematics to detect changes in loading of the limbs. RESULTS: When pressure on the sole of the hindlimb was present, horses were judged as lame (grade 2 on the AAEP scale 1-5) by an experienced clinician. No significant unloading of this limb was found in the group of horses (unloading was observed in 4 animals, but was not detectable in the other 2), but statistically significant effects on back kinematics were detected. The overall flexion-extension (FE) range of motion (ROM) of the vertebral column was increased at walk, especially in the thoracic segments. Axial rotation (AR) ROM of the pelvis was also increased. At trot, the FE ROM was decreased only in the segment L3-L5-S3. During the stance phase of the lame limb, the segment T6-T10-T13 was more flexed and the neck was lowered at both gaits; the thoracolumbar segments were more extended at walk and trot. There were no significant changes in the stride length or protraction-retraction angles in any of the limbs. CONCLUSIONS: Subtle hindlimb lameness provoked slight but detectable changes in thoracolumbar kinematics. The subtle lameness induced in this study resulted in hyperextension and increased ROM of the thoracolumbar back, but also in decreased ROM of the lumbosacral segment and rotational motion changes of the pelvis. POTENTIAL RELEVANCE: Even subtle lameness can result in changes in back kinematics, which emphasises the intricate link between limb function and thoracolumbar motion. It may be surmised that, when chronically present, subtle lameness induces back dysfunction.