Proximal hindlimb flexion in the horse: Effect on movement symmetry and implications for defining soundness

Abstract

Proximal hindlimb flexion may elevate the asymmetry of a slightly lame limb above the threshold for visibility, thus assisting in the clinical gait examination. Further work is needed to examine the causes for a positive response to flexion and possible differences between sound and lame horses as well as horses of different athletic disciplines.

Understanding hind limb lameness signs in horses using simple rigid body mechanics

“…Seven horses featured twice, being recorded before and after notable responses to a hind limb flexion test which induced hind limb lameness (Starke et al, 2012b). Two other horses featured twice, being recorded more than two years apart.…”

To limp, or not to limp, is that the question?

“…Well, without doubt, we can now accurately and precisely quantify upper body movement (head nod and hip hike) of horses in a variety of clinically relevant exercise conditions such as flexion tests (Starke et al, 2012) and lunging (Rhodin et al, 2013), or under the saddle (Robartes et al, 2013). When applying these techniques it becomes increasingly clear that not many horses present 100% symmetrically, similar to humans (Herzog et al, 1989).…”

Is a standalone inertial measurement unit accurate and precise enough for quantification of movement symmetry in the horse?

“…The sternum has been used previously (Barrey et al, 1994) and body orientation seems better suited than head orientation. In multi-sensor systems with synchronized sensors (Warner et al, 2010, Starke et al, 2012a,c, Pfau et al, 2012, the sacral sensor can be used to segment all sensor data (Starke et al, 2012b). If thoracic limb hoof contact is required, IMUs located on the distal limb (Olsen et al, 2012) or hoof mounted accelerometers or gyroscopes (Witte et al, 2004, Keegan et al 2005 provide precise results.…”

“…Consequently IMUs are ideally suited to support clinical decision making by providing objective evidence about changes in movement symmetry (MS) in conjunction with diagnostic tests, such as lunging the horse on hard and soft ground (Chateau et al, 2011, Rhodin et al, 2010, Walker, et al, 2010, flexion tests (Starke et al, 2012a), and diagnostic regional analgesia (Smith and Pfau, 2010). Large-scale studies are needed to establish reference intervals Geffré et al, 2009) for non-lame horses and minimal clinically important differences (Sloan, 2005, Turner et al, 2010 to support clinical decision making.…”

“…Bias and limits of agreement (Bland and Altman, 1986) were established with respect to a validated system based on multiple synchronized 6-DoF IMUs (MTx, Xsens, The Netherlands, Pfau et al, 2005, 2007, Warner et al, 2010, Starke et al, 2012a, 2012c). …”