HOW TO INJECT THE LUMBAR ARTICULAR
PROCESSES OF THE HORSE USING
ULTRASOUND GUIDANCE
Ann Carstens
BVSc, MS, MMedVet(LA Chir), DTO, MMedVet(Diag Im), Dipl ECVDI, PhD
Clinical conditions of the back of the horse are usually as result of traumatic or
degenerative conditions and often result in poor performance. Before the
advent of diagnostic ultrasonography, examination of this area of the horse
was limited to clinical evaluation, radiography and scintigraphy and the
administration of local anaesthesia in specific areas. Optimal radiographic
images are still often only obtained in areas such as spinous processes or the
backs of smaller horses and foals, due to the width and density of the tissues
present in average size adult horses.
Ultrasonography has made the evaluation of the thoracolumbar articulations
possible.
To visualize the thoracolumbar articular processes a curvilinear 2-4 MHz
transducer is required. Generally clipping, followed by a good wash with soap
and water of the area, results in superior images, but washing followed by
alcohol and / or generous acoustic coupling gel application often is quite
adequate.
The back:
Structures on the dorsum of the back can be evaluated including the epaxial
musculature, the supraspinous ligament (SL), the dorsal spinous processes
(DSPs), the dorsal aspect of the ribs, the dorsum (laminae) of the thoracic and
lumbar vertebrae, the lumbar transverse processes (LTPs) and the articulation
processes of the thoracic and lumbar vertebrae (L-AFs, Th-AFs).
As in any other ultrasonographic evaluation, the examination should be done
in a sequential complete fashion. Generally the dorsum is first examined,
viewing the supraspinous ligament and dorsum of the spinous processes with
a 5-7.5 MHz transducer, initially longitudinally followed by a transverse
evaluation.
The SL is seen as a tendinous structure with parallel fibre alignment dorsal to
the DSPs undulating ventrally between the DSPs in the interspinal spaces
where it can appear more hypoechoic. Laterally to the SL the
musculotendinous longisimus muscle may appear isoechoic to the SL and
should not be confused with it. The DSPs of the caudal thoracic and lumbar
vertebrae should have a relatively smooth hyperechoic cortex. The
interspinous area can be interrogated for irregular new bone formation due to
interspinous enthesopathy.
Moving laterally, and requiring a lower frequency transducer, the epaxial
musculture can be evaluated for asymmetry in size and /or abnormal
echogenicity due to haemorrhage or other injury. Particularly the multifidus
muscles have been reported to undergo atrophy with articular process
15-‐18
February
2016
East
London
Convention
Centre,
East
London,
South
Africa
105