Effects of Hindlimb Lameness on Thoracolumbar Displacement

Background: 

Hindlimb lameness is thought to impact thoracolumbar biomechanics in horses and cause secondary (or exacerbate primary) back pathology. Further investigation of the relationship is needed. 

Objectives:

It was hypothesised that resolution of hindlimb lameness using diagnostic anaesthesia would lead to increased displacement of the thoracolumbar spine. 

Study design: 

Retrospective analysis of clinical data. 

Methods: 

Objective data collected using an eight-sensor inertial measurement system during clinical examinations of horses with lameness localised to the tarsal region were inspected. Dorso-ventral (DV) and latero-medial (LM) displacement of the sensors attached to the mid-thoracic and mid-lumbar spine were determined whilst the horses were trotted in hand in a straight line on a firm, flat surface. Data from before and after the resolution of hindlimb lameness using diagnostic anaesthesia were normally distributed and subsequently compared using a paired t-test. Results are presented as mean±SD. Significance was set as p < 0.05. 

Results: 

Seven horses met the inclusion criteria for this study. Prior to diagnostic anaesthesia the mean DV displacement of the lumbar spine was 76.1 ± 13.1 mm which significantly increased by 4.9 ± 2.3 mm following successful resolution of hindlimb lameness (p = 0.001). No significant differences were noted in LM displacement of the lumbar spine, or in DV or LM displacement of the thoracic spine. Main limitations: Small sample size, speed not a controlled variable, primary back pathology not investigated. Conclusions: These data support the assumption that hindlimb lameness has a direct effect on kinematics of the back. Further work is warranted to evaluate the long-term adaptations of thoracolumbar biomechanics following improvement in hindlimb lameness. Ethical animal research: Ethical approval granted by the ethics committee of the School of Veterinary Medicine and Science, University of Nottingham. Informed consent: Not stated. 

Competing interests: 

None declared. 

Sources of funding:

None.