Precision and accuracy of ground reaction force normalization in a heterogeneous population of dogs.
OBJECTIVE
To determine if currently used ground reaction force (GRF) normalization methods are accurate and precise enough to be used on a single-limb basis.


METHODS
Prospective clinical trial.


METHODS
Clinically normal (n = 69) dogs and 40 dogs with unilateral ruptured cranial cruciate ligaments (CCL).


METHODS
Pelvic limb GRFs of orthopedically normal dogs and those with unilateral ruptured CCL were collected. Normalization methods included none, body weight (BW), withers height (WH), WH and relative velocity (WH*F) and principal component 1 (PC1). Normalization methods were evaluated both by individual GRFs and additively. Binary logistic regression was performed for all normalization methods; sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) calculated. Stepwise backward logistic regression was used; significant values were retained in the final model. P < .05 was significant.


RESULTS
Normalization of contact time (CT) by BW uniformly increased sensitivity, specificity, PPV, NPV, and accuracy. SI was the most accurate at both the walk and trot (accuracy 80-96%). Normalization by BW, WH, and WH*F all achieved similar results. When normalized GRFs were added, the accuracy increased only at the walk.


CONCLUSIONS
CT should be normalized to BW. SIs remain the gold standard, if SIs cannot be used, combining GRFs normalized to BW will result in high precision (80%) and high accuracy (89.5%) at the walk. At the trot, normalization by BW, WH and WH*F results in consistent results for the individual GRFs, though not all accuracies are >80%.
Department of Clinical Sciences, Cornell University, Ithaca, New York.
Ursula
U
Krotscheck
Rory J
RJ
Todhunter
Samantha A
SA
Nelson
Nathaniel B
NB
Sutter
Hussni O
HO
Mohammed
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D004283:Dog Diseases / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D005260:Female; D005684:Gait / Q000502:physiology*; D008297:Male; D010027:Osteotomy / Q000662:veterinary; D012421:Rupture / Q000601:surgery / Q000662:veterinary*