A TWO-DIMENSIONAL ANALYSIS OF LIMB SYMMETRY IN THE TROT OF. Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University

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1 A TWO-DIMENSIONAL ANALYSIS OF LIMB SYMMETRY IN THE TROT OF LABRADOR RETRIEVERS by Robert L. Gillette, D.V.M., M.S.E. Carole J. Zebas, P.E.D. Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University Department of Health, Sport, and Exercise Science, University of Kansas Scott-Ritchey Research Center College of Veterinary Medicine Auburn University, AL Department of Health, Sport, and Exercise Science University of Kansas Lawrence, KS Abstract: 96 words

2 A Two-Dimensional Analysis of Limb Symmetry in the Trot of Labrador Retrievers Robert L. Gillette, DVM, MSE Carole J. Zebas, PED Sixteen sound Labrador retriever and Labrador retriever cross-breed adult dogs were evaluated for symmetry while in a trot gait using a two-dimensional motion analysis system. Reflective markers were placed at selected joint centers. Each dog had the right side and then the left side videotaped while in the trot gait. The markers on the videotape were then digitized for analysis. There was no significant difference (p>.05) between the movements of the two sides. It was concluded that the trot gait is symmetrical and that a two-dimensional system can be used to analyze gait in the dog.

3 A Two-Dimensional Analysis of Limb Symmetry in the Trot of Labrador Retrievers Robert L. Gillette, DVM, MSE Carole J. Zebas, PED Introduction Body movement can be used to evaluate the physical status of the subject in question. By understanding and defining normal movement one can then evaluate abnormal movement. Animal movement has been a subject of research for a long period of time. 1 Both qualitative and quantitative gait analyses have been used to analyze horse and dog movement. 2,3 It has been used to evaluate normal gaits (i.e., trot), and abnormal gaits in dogs with hip dysplasia and cranial cruciate ligament rupture. 4,5,6 Limb symmetry indices have been evaluated using ground reaction forces and kinematically to assess hind limb symmetry. 7,8 Motion analysis can play a very important role in helping to understand how the body is functioning. Veterinarians, breeders, owners, and trainers all can potentially benefit from the recent advances in gait analysis. Improved capabilities for data collection, storage, and analysis in combination with the advancements in personal computer technology have provided an opportunity for these analytical techniques to be utilized in the respective areas of interest. Currently these capabilities are only accessible at the institutional level, or they are so highly technical that its use is limited. A priority should be placed on researching methodologies that provide these tools to the professionals who can utilize them.

4 The objective of this study was twofold: 1) to kinematically describe the trot in the Labrador retriever/labrador cross-breed dog; and 2) to assess the limb symmetry in the trot of the Labrador retriever using a two-dimensional video analysis system. Materials and Methods The study was conducted under protocols approved by the Auburn University Institutional Animal Care and Use Committee and the University of Kansas Institutional Animal Care and Use Committee. Animals Sixteen clinically sound Labrador retriever and Labrador cross-breed dogs who were older than two years of age, and younger than eight years participated in the study. Veterinary records for each participant were examined for any historical orthopedic abnormalities. Soundness by examination was defined as a 0 degree of lameness when using the lameness quantification system described by Sumner-Smith. 9 Experimental Design Reflective markers were placed at the joints of the defined body segments. This was done by first placing masking tape over the predefined locations. An adhesive glue was applied to the back of the reflective markers and then the marker was attached to the tape at the anatomical point to be measured. The axial markers were placed behind the ear on the lateral aspect of the atlantal vertebral bone, on the dorsal aspect (point of cranial angle) of the scapula, on the dorsal point of the iliac crest, and on the lateral point of the

5 ischial tuberosity. The front leg appendicular markers were placed on the acromion/greater tubercle of the scapulohumeral joint, on the lateral epicondyle of the humerus, on the ulnar styloid process/ulnar carpal bone of the carpus, and on the distal lateral aspect of the fifth metacarpal bone. The rear leg appendicular markers were placed on the eminence of the greater trochanter of the femur, on the femorotibial joint midpoint between the lateral epicondyle of the femur and the fibular head, on the lateral prominence of the malleolus of the distal tibia, and on the distal lateral aspect of the fifth metatarsus. The test area was a level and even roughened concrete surface. The camera was placed perpendicular to the movement of the canine subject 20 feet from the test subject path. The movement was filmed by an SVHS videocamera a at a speed of 60 Hz using a shutter speed of 1/500 seconds. A handler led the dogs on the test path at a speed that induced a trot gait. The dogs were trotted on the test path first with their right side perpendicular to the camera and then with their left side perpendicular to the camera. This was repeated for three sequences. After filming, the videotape was subjected to a kinematic analysis using the Peak5 motion analysis software package. b The reflective balls were used in locating the x and y coordinates for each of the joint centers. Motion Evaluation The linear kinematic parameters measured were the stride length, stride frequency, stride time, and linear velocity. The angular kinematic parameters were the angular displacement of the shoulder, elbow, carpal, hip, knee, and tarsal joints and the angular

6 velocity of the shoulder and hip joints. A Butterworth filter, which is incorporated within the Peak Performance analysis software b, was used on the kinematic data. The results of the three sequences were then averaged for repeatability using a coefficient of variance. After defining the linear kinematic parameters, the angular parameters of the right side were compared with those of the left side to assess symmetry. Statistical Analysis Paired t-tests were used to determine if there was a significant difference between kinematic parameters. All parameters that did not have a significant difference between the paired right and left sides were considered symmetrical. Results For reliability one dog was put through the methodology three times. The coefficient of variance, significance < 0.10, was determined for the angular displacement of the shoulder, elbow, carpus, hip, knee and the tarsus for both the right side and the left side. The results are seen in Table 1. The values from the right side were then compared to the left side using a paired t- test statistical equation with a significance level of p<0.05. The means, standard deviations, maximums, and minimums of the linear kinematic parameters are shown in Table 2 and summarized in Figure 1. The means, standard deviations, maximums, and minimums of the angular kinematic parameters are shown in Table 3 and summarized in Figure 2. The results of the t-test scores are listed in Table 4. There was no significant difference between the values derived for both the right and the left side.

7 Discussion Body movement can be used to evaluate lameness and gait abnormalities in the dog. If normal movement is symmetrical between both sides of the body than any abnormal movement of a body segment would produce asymmetrical locomotion. This plays an important role in the evaluation of conformation, lameness, performance, and rehabilitation. The significance of the reliability showed that the methodology used in this study was consistent and repeatable. There was no significant difference between the kinematic measurements of the right side and those of the left side. Healthy, sound Labrador retrievers and Labrador retriever cross-breed dogs move symmetrically while in a trot gait. Previous studies have established that computer-assisted videographic gait analysis can be used to analyze canine locomotion. These studies were performed using a three-dimensional motion analysis system. The average stride length for this study was longer, the average stride frequency faster, and the linear velocities faster than that reported in other studies. 4,10 There was also an increase in the degrees of angular displacement in this study as compared to the other studies, as seen in Table 5. These somewhat higher values could be a result of the trotting pace differences in previous studies. Another reason for the higher values could be in the way the parameters were defined. The lack of a significant difference between the kinematic measurements of the two sides shows that it is possible to use the two-dimensional analysis system for determining gait symmetry. One previous study used a two-dimensional system to

8 characterize normal locomotion of the dog using nonlinear dynamic stability measurements. 11 Using the protocol described in our study, the movements filmed on the right side can be used to compare to the movements filmed on the left side. The twodimensional system can be used as an alternative to the three-dimensional system to measure body symmetry. Conclusions There are three areas of conclusions as a result of this study. The first is that there were no significant differences found between the right and left side parameters in sound dogs. This has the potential to be used diagnostically, in that, a parameter on one side of the body could be used as the control for the same parameter on the opposite side. When assessing gait and joint movement in the trot, any difference between the two sides could be used help diagnose lameness. Further tests are needed to evaluate using this methodology on unsound or lame subjects. Second, the results also show that a two-dimensional analysis system is both valid and reliable. It allows filming one side of the body to be followed by filming on the opposite side of the body with similar results. The two-dimensional analysis system is more economical than the three-dimensional system and because of this, would be more affordable to those individuals that could utilize these methodologies. The third conclusion is that filming outside of the laboratory is possible. Not everyone will have the potential to purchase a motion analysis system. These individuals could send videotapes to the laboratories that have these systems for gait analysis. Any

9 individual that would be willing to learn the protocol could then utilize the benefits of computer-assisted video gait analysis. Future studies should include more information on the different breeds. This would help in defining the conformation standards for breeding purposes. Analysis of more sound dogs in general would define the normal maximum and minimum ranges. This would help when analyzing gait diagnostically. Increasing the numbers of dogs analyzed that have pre-diagnosed musculoskeletal pathologies would set standards for the parameters that are associated with those specific etiologies. Once some of these standards are set, this methodology can be used to quantify response to treatment in a clinical setting or in the research environment. Professionals, trainers, and owners should be educated on the use of computerassisted video gait analysis. The more information that is distributed the greater the potential to benefit from the knowledge gained about animal locomotion.

10 Footnotes a. Panasonic Systems Co. Secaucus NJ b. Peak Performance Technologies Inc. Englewood, CO 80112

11 References 1. Leach DH, Dagg, AI. Evolution of equine locomotion research. Equine Vet J 1983;15: DeCamp CE. Kinetic and kinematic gait analysis and the assessment of lameness in the dog. Vet Clin North Am (Sm Anim Pract) 1997;27: Leach DH, Dagg AI. A review of research on equine locomotion and biomechanics. Equine Vet J 1983;15: DeCamp CE, Soutas-Little RW, Hauptman J, et al. Kinematic gait analysis of the trot in healthy Greyhounds. Am J Vet Res 1993;54: Bennet RL, DeCamp CE, Flo GL, et al. Kinematic gait analysis in dogs with hip dysplasia. Am J Vet Res 1996;57: DeCamp CE, Riggs CM, Olivier NB, et al. Kinematic evaluation of gait in dogs with cranial cruciate ligament rupture. Am J Vet Res 1996;57: Budsberg SC, Jevens DJ, Brown J, et al. Evaluation of limb symmetry indices, using ground reaction forces in healthy dogs. Am J Vet Res 1993;54: Schaefer SL, DeCamp CE, Hauptman JG, et al. Use of kinematic analysis to evaluate hind-limb symmetry of the trot in healthy dogs. Vet Surg 1996;25: Sumner-Smith G. Gait analysis and orthopedic examination, in D.S. Slatter (ed.), Textbook of Small Animal Surgery 1993; Allen, K., DeCamp, C. E., Braden, T. D., & Bahns, M. Kinematic gait analysis of the trot in the healthy mixed breed dogs. Veterinary and Comparative Orthopedics and Traumatology 1994;7:

12 11. Marghitu DB, Kincaid SA, Rumph PF. Nonlinear dynamics stability measurements of locomotion in healthy Greyhounds. Am J Vet Res 1996;57:

13 Table 1 Reliability of the Digitizing Technique Angular Displacement Measurements Joint Body Side Sequence 1 Sequence 2 Sequence 3 Co. Var.* Shoulder Right Shoulder Left Elbow Right Elbow Left Carpus Right Carpus Left Hip Right Hip Left Knee Right Knee Left Tarsus Right Tarsus Left Note. The values for the measured angular displacements are in degrees. *Co. Var. stands for Coefficient of Variance values

14 Table 2 The Mean, Standard Deviation, Maximum, and Minimum Values of the Linear Kinematic Parameters Kinematic Parameter* Body Side Mean S D Maximum Minimum Stride Length (m) Right Stride Length (m) Left Stride Time (s) Right Stride Time (s) Left Linear Velocity (m/s) Right Linear Velocity (m/s) Left Stride Frequency (str/s) Right Stride Frequency (str/s) Left *m = meters; s = seconds; str = strides; S D = standard deviation

15 Table 3 The Mean, Standard Deviation, Maximum, and Minimum Values of the Angular Kinematic Parameters Kinematic Parameter* Body Side Mean S D Maximum Minimum Shoulder ROM (degs) Right Shoulder ROM (degs) Left Elbow ROM (degs) Right Elbow ROM (degs) Left Carpal ROM (degs) Right Carpal ROM (degs) Left Hip ROM (degs) Right Hip ROM (degs) Left Knee ROM (degs) Right Knee ROM (degs) Left Tarsus ROM (degs) Right Tarsus ROM (degs) Left Shoulder AV CW (degs/s) Right Shoulder AV CW (degs/s) Left Shoulder AV CCW (degs/s) Right Shoulder AV CCW (degs/s) Left Hip AV CW (degs/s) Right Hip AV CW (degs/s) Left

16 Hip AV CCW (degs/s) Right Hip AV CCW (degs/s) Left *ROM = angular displacement; degs = degrees of movement; AV = angular velocity; CW = clockwise movement; s = seconds; CCW = counterclockwise movement S D = standard deviation

17 Table 4 Results of the Statistics for the Comparison of Right and Left Kinematic Parameters Kinematic Parameter* T-test Value Deg. of F. P Value Significance Stride Length NS Stride Time NS Linear Velocity NS Stride Frequency NS Shoulder ROM NS Elbow ROM NS Carpal ROM NS Hip ROM NS Knee ROM NS Tarsal ROM NS Shoulder CW AV NS Shoulder CCW AV NS Hip CW AV NS Hip CCW AV NS *ROM = angular displacement; CW = clockwise movement; AV = angular velocity; CCW = counterclockwise movement Deg. of F. = degrees of freedom NS = non significant

18 Table 5 Angular displacement values of right side joints while in the trot compared to previously reported right side values. Joint This Study's Results Allen, et al. 10 DeCamp, et al. 4 Shoulder Elbow Carpus Hip Knee Tarsus Note. The values for the measured angular displacements are in degrees.

19 Legends Figure 1. A graph comparing the means of the linear kinematic parameters of the right side to those of the left side from dogs undergoing two-dimensional gait analysis. Figure 2. A graph comparing the means of the angular kinematic parameters of the right side to those of the left side from dogs undergoing two-dimensional gait analysis. Measurements are in degrees of range of motion.

20 Linear Parameters of Labrador Retrievers in the Trot.* m/s 2.40 m/s 2.35 str/s 2.33 str/s m 1.19 m Right Left s 0.43 s 0.00 Stride Length Stride Time Linear Velocity Stride Frequency *m = meters; s = seconds; m/s = meters per second; str/s = strides per second

21 Joint Range of Motion per Stride of Normal Labrador Retrievers ROM * (degrees) Right Left Shoulder Elbow Carpus Hip Knee Tarsus * ROM = Angular Displacement