Quantitative gait analysis, why would you use it?

Quantitative (or objective) gait analysis technology, such as the Sleip app, is not such a recent development as you might think. There is a long history of interest in horse locomotion, with early papers originating from the 17^th and 18^th centuries, via reports on the first use of computer technology in equine gait research to multiple companies offering systems for clinical use nowadays. But why did this technology actually arise? And why do more and more clinicians use quantitative gait analysis on a daily basis anno 2023? In this blog, I’ll discuss the ‘why’ behind equine quantitative gait analysis to give you more insight into the added value of using gait analysis in your daily practice. 

The current situation

First of all, lameness is the most expensive health issue in the equine field. In the US, economic costs are estimated between 680 million and 1 billion dollars a year [1]. Also, equine veterinarians spend most of their time doing lameness assessments [2]. Furthermore, research shows that a large proportion of sports horses (72,5%!), deemed sound by their owners, show a significant asymmetry in their locomotion pattern when measured with quantitative gait analysis [3]. As you are likely aware of, intensive societal discussions around the welfare aspects of equestrian sports are held [4,5]. Quantitative gait analysis can help to objectify these discussions, thereby giving us the opportunity to be more transparent about the clinical examination of (sports) horses.

Agreement between veterinarians

A lot of research has been done to investigate the agreement between veterinarians during the clinical orthopaedic examination. This agreement, on the primary lame limb as well on lameness grade, came frequently out as poor [6,7,8,9,10]. Also, the agreement on whether horses were fit-to-compete (or not) was not convincing with 58% during live assessment and 71-73% during video assessment [11].

Physical limitations

Looking at the physical abilities of human beings, there are also some arguments on why quantitative gait analysis is of added value. First of all, the time resolution of the human eye is limited with 10-15 samples per second [12]. This makes the stride frequency at trot quite challenging for our biological image processing system. Secondly, humans are poor in identifying subtle asymmetries with high precision [13], which is exactly the task to be performed during the visual exam of subtle lamenesses. It was also shown that the reliability of evaluating hindlimb lameness is generally lower compared to forelimb lameness [14,15].

Psychological limitations

Not only the physical abilities can limit our performance as veterinarians, psychological limitations may also play a role. One of the psychological effects is the so-called ‘expectation bias’ [16,17]. In other words; you are biased by the expectations you have on forehand. This can be caused by the anamnesis, medical records, diagnostic imaging that’s already performed, conversations with your client or just the fact that it is a Friday afternoon and you want this diagnostic analgesia to be positive. Don’t blame yourself, all humans are prone to this effect. You can eliminate this effect though, by using quantitative gait analysis during your orthopaedic examinations.

Scaling of lameness

Another issue with our visual orthopaedic exam, is the fact that different lameness scales are used globally, which makes the comparison of documentation of different veterinarians complicated. Some lameness scales also have clear imperfections when it comes to accurately documenting the lameness. 

Or, as dr. Sue Dyson said ‘The problem lies in the absence of a universally accepted method of lameness grading that is easy to define, readily repeatable by an observer, reproducible among observers, and that takes into account the vast spectrum of the clinical presentations of lameness ‘[18].

How we perceive and assess lameness

The perception of lameness, especially on the lunge, varies a lot between veterinarians [19,20]. Different visual lameness indicators such as head movement, stride length or hock flexion are mentioned when veterinarians were asked to describe the factors they take into consideration for determining the presence of forelimb and/or hindlimb lameness [21].

The opinion of the equine veterinarian using quantitative gait analysis

But what about the opinion of the current veterinarians themselves? A questionnaire was sent to collect information on why veterinarians choose to use quantitative gait analysis in their clinic or practice. Several arguments were given as a response: transparency in the clinical examination, documentation of the clinical examination, educational purposes, service for their clients, being part of innovation within the equine veterinary sector, the added value during sports horse monitoring and the possibility for doing tele-medicine [22].

In this blog, I tried to give you an overview of all evidence-based argumentation on why to use quantitative gait analysis in your daily practice or clinic. The added value hopefully becomes clear while reading. Feel free to reach out if you want to know more about Sleip or in case of questions around the use of the Sleip application in your daily routine!, Aagje Hardeman.

— Dr. Aagje Hardeman, DVM, PhD, Customer Success Manager at Sleip.

-------------------------------------------------------------------------------------------------------------------

References

[1] United States; National Animal Health Monitoring System (U.S.). National Economic Cost of Equine Lameness, Colic, and Equine Protozoal Myeloencephalitis (EPM) in the United States; Number 3 p. in APHIS Veterinary Services Info Sheet; U.S. Department of Agriculture, APHIS: Fort Collins, CO, USA, 2001.

[2] Loomans J. et al. (2007) A survey of the workload and clinical skills in current equine practices in The Netherlands.

[3] Rhodin M. et al. (2017) Head and pelvic movement asymmetries at trot in riding horses in training and perceived as free from lameness by the owner. PLoSONE 12(4):e0176253. https://doi.org/10.1371/journal.pone.0176253 

[4] Bouter, S. (2019) Strengere regels voor dansen met paard moeten sport redden NRC Handelsbl. https://www.nrc.nl/nieuws/2019/08/21/strengere-regels.voor.dansen-met-paard-a3970685     

[5] Pinedo, D. (2019) Dressuurtoppers Van Grunsven en Werth vreyen voor einde paardensport. NRC Handelsbl. https://nieuws/2019/08/19/dressuurtoppers-van-grunsven-en-werth-vrezen-voor-einde-paardensport-a3970494 

[6] Fuller, C. et al. (2006) The intra- and inter-assessor reliability of measurement of functional outcome by lameness scoring in horses. Vet. J.171, 281-286

[7] Hammarberg M. et al. (2016) Rater agreement of visual lameness assessment in horses during lungeing. EVJ 48, 78-82

[8] Hewetson, M. et al. (2006) Investigation of the reliability of observational gait analysis for the assessment of lameness in horses. Vet. Rec.158, 852-858

[9] Keegan, K. et al. (1998) Evaluation of mild lameness in horses trotting on a treadmill by clinicians, interns or residents and correlation of their assessments with kinematic gait analysis. Am. J. vet. Res.59, 1370-1377.

[10] Keegan, K. et al. (2010) Repeatability of subjective evaluation of lameness. EVJ (42), 92-97.

[11] Serra Braganca et al. (2020). Subjective and objective evaluations of horses for fit-to-compete or unfit-to-compete judgement. Vet. J. 257

[12] Holcombe et al. (2009) Seeing slow and seeing fast: two limits on perception. Trends in cognitive sciences (13) 5, 216-221

[13] Parkes et al. (2009) Evidence of the development of ‘domain-restricted’ expertise in the recognition of asymmetric motion characteristics of hindlimb lameness in the horse. EVJ 41 (2) 112-117.

[14] Peham, C. et al. (2001) Hindlimb lameness: Clinical judgement versus computerised symmetry measurement. Vet. Rec.(148) 750-752.

[15] Peham, C. et al. (1999) Supporting forelimb lameness: Clinical judgement vs. computerised symmetry measurement. EVJ (31) 417-421.

[16] Arkell et al. (2006) Evidence of bias affecting the interpretation of the results of local anaesthetic nerve blocks when assessing lameness in horses. Vet. Rec.(159) 346–349.

[17] Hardeman et al. (2022) Visual lameness assessment in comparison to quantitative gait analysis in horses. EVJ (54) 1076-1085.

[18] Dyson, S. (2011) Can lameness be graded reliably? EVJ (43) 379-382.

[19] Ross MW. Chapter 7. Movement. In: Ross MW, Dyson SJ, editors. Diagnosis and management of lameness in horses. Elsevier Saunders; 2011.

[20] Stashak TS. Chapter 3. Examination for lameness. In: Stashak TS, editor. Adams’ lameness in horses. Baltimore: Lippincott Williams & Wilkins; 2002.

[21] Starke et al. (2022) Expert visual assessment strategies for equine lameness examinations in a straight line and a circle: A mixed methods study using eye tracking. Vet.Rec. e1684.

[22] Hardeman et al. (2021) A first exploration of perceived pros and cons of quantitative gait analysis in equine clinical practice. EVE 2021 doi:10.1111/eve.13505.