The axial skeleton

Question 1

Clinical examination of the axial skeleton

Answer 1

start with neck palpation and baited stretches

Move caudally along the axial skeleton

Deep, sustained pressure onto the epaxial muscles of the thoracic and lumbar spine. Can apply pulsatile pressure to assess ability to ventral flex.

Assess – muscle mass, muscle tone, symmetry and pain on palpation

Question 2

Epaxial muscles

Answer 2

Muscles above the ribs/transverse processes

Responsible for spinal stability and lateral flexion

Longissimus, multifidus

Question 3

Sternal lift

Answer 3

sustained pressure applied to the sternum to encourage dorsiflexion of the cranial thoracic spine

Question 4

Abnormalities you might see with a sternal lift

Answer 4

Lack of response

Transient response that cannot be maintained

Overt objection to dorsiflexion – watch out!!

Question 5

Abnormal responses to palpation of the sacroiliac region - either side of the midline

Answer 5

Horses with discomfort in this region often “shrink” towards the floor and hyperextend the region

Some horses show a marked pain response and can kick out

Question 6

How do you achieve lumbosacral dorsiflexion in a horse?

Answer 6

Apply pressure to the skin either side of the tail base

Horse should dorsiflex lumbar spine and lumbosacral joint

Drop tuber ischii towards the floor

Remain relaxed

Question 7

Abnormal responses to lumbosacral dorsiflexion pressure

Answer 7

No response

Unable to maintain the flexion for more than a few seconds

Outward signs of pain or discomfort

Question 8

How many cervical vertebrae are there?

Answer 8

7

Question 9

What are the main manifestations of cervical disease?

Answer 9

Neck pain/dysfunction

Forelimb lameness

Ataxia - cervical stenotic myelopathy

Question 10

Signs of neck pain

Answer 10

Reduced range of motion during baited stretches

Changes in position or posture

Palpation findings – enlarged joints

Reduction in muscle mass

Question 11

Two mains mechanisms of forelimb lameness

Answer 11

A consequence of muscle dysfunction

Radiculopathy - neuropathic pain

Question 12

Muscle dysfunction

Answer 12

Many cervical muscles are involved in protraction of the forelimb

Brachiocephalicus – changes in strength or function can cause asymmetry

Question 13

Reticulopathy - neuropathic pain

Answer 13

Compression of a spinal nerve root in the caudal cervical region (feeding brachial plexus)

Enlarged APJs are the culprit

Question 14

Diagnostic imaging of the cervical spine

Answer 14

Radiography is the most common first line but its lacks diagnostic acuity.

CT is the only 3D imaging modality that can accommodate the equine neck!
- often combined with diagnostic accuracy

Question 15

Treatment of pain in the cervical spine

Answer 15

Intra-articular medication with corticosteroids is the mainstay

Cannot reverse bone remodeling but can alleviate pain and reduce associated soft tissue inflammation

There are no landmarks on the surface, and the target is deep beneath muscle…

Injections are performed under ultrasound guidance.

Question 16

Prognosis of cervical spine pain

Answer 16

Variable and often unpredictable

Neck pain > radiculopathy > spinal ataxia

Question 17

Clinical signs of thoracolumbar disease

Answer 17

Poor muscling

Pain on palpation

Abnormal dynamic responses

Resentment of ridden exercise

Poor quality canter (vs trot)

Question 18

Radiography of thoracolumbar spine

Answer 18

Laterolateral views are most commonly acquired and are excellent for disease affecting the dorsal spinous processes.

CARE – you can find dorsal spinous process disease in a large proportion of horses with no back pain!!

Question 19

Other imaging modalities of thoracolumbar spine

Answer 19

Gamma scintigraphy (bone scan)
- inject a bisphosphonate

Response to local anaesthesia

Response to local anti-inflammatories

Question 20

Treatment of thoracolumbar spine

Answer 20

Medical management and rehabilitation is probably the starting point for most cases:

• Local injection of corticosteroids
• Rehabilitation program to restore strength and function

This can be curative in some cases, can be repeated in cases with good responses.

Frequency of injection often reduces with time as they become stronger.

Question 21

Surgical management of thoracolumbar spine pain

Answer 21

Interspinous ligament desmotomy

Subtotal (cranial wedge)

Question 22

Interspinous ligament desmotomy

Answer 22

To help with thoracolumbar spinal pain

Cutting the interspinous ligament

Disadvantage: Doesnt change the underlying anatomy

Advantage: short rehab period

Question 23

Disadvantages of a subtotal (cranial wedge) ostectomy

Answer 23

Invasive procedure

Post-operative pain

Long rehabilitation period - up to 6mo for owners so may not be possible for everyone

Question 24

Advantages of subtotal (cranial wedge) ostectomy

Answer 24

Permanent anatomy change

Better long term outcomes

Question 25

Articular process joint disease

Answer 25

Diagnosis can be achieved using oblique radiography, U/S, and gamma scintigraphy

Manage with U/S guided steroid injections

Question 26

Lumbosacral and sacroiliac joint disease

Answer 26

There aren’t many clinical signs that differentiate LS from SI pain (or even from TL pain!)

The “typical” horse with LSI dysfunction:
* Can buck under saddle
* Becomes disunited at canter
* Has poor hind limb engagement
* Occasionally has overt lameness

Question 27

Diagnostic anaesthesia of the SI joint

Answer 27

Inject local anaesthetic into the sacroiliac joint bilaterally

Ideally observe the horse ridden before and after blocking

Not a risk-free procedure:
* The sacroiliac joint is extremely close to some important structures
* Inadvertent blockade of the cranial gluteal nerve is possible
- Horse can become recumbent for 3-4 hrs
- <5%

Question 28

Imaging of the sacro-iliac joint

Answer 28

Scintigraphy

Transrectal U/S

Question 29

Scintigraphy of the SI joint

Answer 29

Scintigraphy can be very useful but there are false positives and negatives….

Added benefits:
* Identify concurrent appendicular or axial pathology

Limitations:
* Expensive - full body bone scan about £1800

Question 30

Transrectal U/S for imaging the SI joint

Answer 30

Can be useful but interpretation can be challenging for inexperienced clinicians

Question 31

Treatment of SI joint disease

Answer 31

Better to think of SI joint medications as regional medications rather than joint specific.

We are treating a syndrome of joint and soft tissue pathologies.

Question 32

Rehabilitation for the axial skeleton

Answer 32

Techniques to improve engagement and muscle recruitment

Water treadmill exercise

Non-ridden rehabilitation

Ridden rehabilitation

Question 33

Techniques to improve engagement and muscle recruitment

Answer 33

can be started early in the rehab process
* Sternal lifts
* LSI dorsiflexion
* Tail pulls

Question 34

Water treadmill exercise

Answer 34

Adds resistance to cranial phase of stride

Increases limb retraction (stride height)

Increases ROM of the axial skeleton

Buoyancy (if deep enough…)

Question 35

What is water treadmill exercise recommended for?

Answer 35

Strength

Coordination

Stability

Postural control

Question 36

Non-ridden rehabilitation

Answer 36

Lunging alone is not extremely helpful…

Some devices can be used to encourage dorsiflexion and muscle recruitment:
* Pessoa systems
* Equiband
* Home-made equivalents!!

Question 37

Ridden rehabilitation

Answer 37

Hill work (trot up and walk down)

Pole exercises (progressing to raised)

Working on a range of surface types

“cross training”