Withers vertical movement symmetry is useful for locating the primary lame limb

Withers vertical movement symmetry is useful for locating the primary lame limb in naturally occurring lameness

Equine Vet J. 2023 May 24. doi: 10.1111/evj.13947. Online ahead of print.
Authors
Emma Persson-Sjodin 1 , Elin Hernlund 1 , Thilo Pfau 2 3 , Pia Haubro Andersen 1 , Karin Holm Forsström 4 , Anna Byström 1 , Filipe M Serra Bragança 5 , Aagje Hardeman 5 6 , Line Greve 7 , Agneta Egenvall 8 , Marie Rhodin 1
Affiliations

1 Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
2 Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
3 Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
4 Equine Clinic, University Animal Hospital, Swedish University of Agricultural Sciences, Uppsala, Sweden.
5 Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
6 DataHorse, Wierden, The Netherlands.
7 Evidensia Specialist Equine Hospital Helsingborg, Helsingborg, Sweden.
8 Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.

PMID: 37226583
DOI: 10.1111/evj.13947

Abstract
in English, German

Background: During orthopaedic assessment of lame horses, a head nod is commonly present in both primary forelimb and hindlimb lame horses. Additional motion metrics that could assist clinicians in correctly differentiating between these two scenarios would be of great clinical value.

Objectives: The primary objective of this study was to examine whether withers movement asymmetry can be used in a clinical setting to distinguish primary forelimb lameness from compensatory head movement asymmetry due to primary hindlimb lameness.

Study design: Retrospective, multicentre study.

Methods: Movement asymmetry of head, withers and pelvis was measured using multi-camera optical motion capture, as part of routine lameness investigations at four European equine hospitals. Vertical movement asymmetry parameters from 317 horses trotting in a straight line were compared before and after successful diagnostic analgesia of a single limb. Descriptive statistics, t-tests and linear models were used to analyse the data.

Results: In forelimb lame horses, 80%-81% showed head and withers asymmetry both indicating lameness in the same forelimb. In hindlimb lame horses, 69%-72% showed head asymmetry ipsilateral to the lame hindlimb and withers asymmetry diagonal to the lame hindlimb, thus, head and withers asymmetry indicated lameness in different forelimbs. A large (>15 mm) compensatory head nod was seen in 28%-31% of the hindlimb lame horses. In 89%-92% of these, head and withers asymmetry indicated lameness in different forelimbs. Withers asymmetry decreased linearly with reduced head or pelvic asymmetry for both forelimb and hindlimb lame horses.

Main limitations: Compensatory strategies were evaluated on group level to identify common patterns, potentially ignoring uncommon individual strategies.

Conclusions: Withers vertical movement asymmetry metrics can be useful in helping to locate the primary lame limb during quantitative lameness assessment. Head and withers movement asymmetry parameters generally indicate the same forelimb in forelimb lame horses, but different forelimbs in hindlimb lame horses.