Flashcards in Orthopaedics - Spine Deck (44)
How many vertebrae make up the cervical, thoracic, lumbar and sacral segments?
7 cervical vertebrae
12 thoracic vertebrae
5 lumbar vertebrae
5 sacral vertebrae
The sacral vertebrae are fused to form a solid mass.
Describe the main characteristics of a vertebra? What processes are given off by the vertebral arch?
The vertebra in each section of the spine have different characteristics, but they all share some common features.
Anteriorly is the vertebral body. Posteriorly, the vertebral arch encloses the spinal canal in which lies the spinal cord. The vertebral arch consists of 2 pedicles which arise from the vertebral body and two flattened laminae that come together to form the posterior wall of the arch.
The vertebral arch gives off a spinous process posteriorly, two transverse processes laterally and four articular processes - two superior and two inferior. The articular processes articulate with the corresponding processes of the vertebra above and below to form facet joints.
What are the anatomical features of cervical vertebrae?
Cervical vertebrae are:
- transverse foramina (for passage of vertebral artery)
- rudimentary transverse processes
- flat facet joints
Anatomical features of thoracic vertebrae?
Thoracic vertebrae are:
- large in size
- larger transverse processes that articulate with the ribs
- heart shaped spinal canal
- oblique facets (causing a natural lordosis)
Anatomical features of lumbar vertebrae?
Lumbar vertebrae are:
- the largest vertebrae
- stout transverse processes
- almost vertical facet joints
Describe the structure of the intervertebral disc?
The IVDs are located between adjacent vertebral bodies. They allow movement between vertebral bodies and act as shock absorbers.
They have a tough, outer fibrocartilagenous annulus fibrosus surrounding a central nucleus pulposus made of water and cartilage.
As an individual gets older, the fibres of the annulus degenerate and weaken. Excessive loading of the disc may result in rupture of the annulus and herniation of the nucleus pulposus. This may press on the nerve root or the spinal cord.
What are the 3 main groups of ligaments that connect vertebrae to one another?
1) Anterior longitudinal ligament - runs as a continuous band along the anterior aspect of the vertebral bodies from skull to sacrum
2) Posterior longitudinal ligament - a band connecting the posterior aspects of the vertebral bodies. It is not as strong as the anterior longitudinal ligament but is important because it forms the anterior boundary of the spinal canal
3) Interspinous ligaments - run between adjacent spinous processes and prevent excessive forward flexion of the spine
How should the neck be examined?
The posture of the neck and any bone tenderness (midline and over the spinous processes) are noted.
Most neck examination is performed in the context of suspect cervical spine injury, so the patient is likely to be immobilised with collar and blocks. If these are safe to remove, check the range of movements: flexion and extension (mainly atlanto-occipital joint), rotation (mainly atlanto-axial joint) and lateral flexion (whole of the cervical spine). Rotation is the movement most commonly affected.
Examine the arms and test for root lesions and reflexes (biceps C5, brachioradialis C6, triceps C7). If cord compression is suspected, examine the lower limbs for signs of this - e.g. hyperreflexia and upgoing plantars.
The main sites of injury are C6 and 7, followed by C2. Roughly 10% of C spine fractures will have another spine fracture eleswhere, so always examine the whole spine!
What is cervical spondylosis?
This refers to degenerative changes of the cervical spine - e.g. degeneration of the annulus fibrosis and bony spurs narrow the spinal canal and intervertebral foramina.
It is extremely common, 90% of men >60 years and women over 50 years exhibit some degree of degeneration. However, it is usually asymptomatic, but can cause neck and arm pain with parasthesia - sometimes with myelopathy (spastic weakness and later, incontinence).
What is mechanical back pain?
Soft tissue injury leads to dysfunction of the whole spine causing muscle spasm and pain.
It may have a precipitating event, e.g. lifting.
Typically happens in younger patients with no sinister features (e.g. weight loss, night sweats etc)
How is mechanical back pain managed?
- Max 2d bed rest
- Education: keep active, how to lift/ stoop
- Warmth - e.g. swimming in a warm pool
- analgesia: paracetamol +/- NSAIDS +/- codeine
- muscle relaxant: low dose diazepam (short term)
What back pain diagnoses should not be missed?
Infection - discitis or epidural abscess
Malignancy - primary or metastatic
Inflammatory conditions - ankylosing spondylitis
Nerve root impingement or cauda equina syndrome
What are the red flag signs for back pain?
Unexpected weight loss
History of cancer
Age of onset <20 or >55 years
Pain worse at night
Neurological deficit - e.g foot drop
Saddle anaesthesia and loss of bladder control
What causes disc herniation?
The vertebrae are separated by intervertebral discs, composed of two parts. The outer fibrous annulus fibrosus and the inner nucleus pulposus.
As part of the natural ageing process, the nucleus pulposus becomes dehydrated and brittle. This is a common cause of mechanical back pain. The annulus fibrosus may also be affected and may split, allowing the nucleus pulposus to leak out.
How do patients present with disc herniation?
If a disc herniation compresses a nerve root, the result is shooting pain, numbness and weakness in the distribution of the affected nerve. This is known as a radiculopathy. The commonest nerve roots to be affected are those supplying the sciatic nerve (L4-S3) causing sciatica. Typically, sciatica pain radiates from the buttock as far as the sole of the foot. The exact presentation depends on the nerve root affected.
How does an L3 nerve root compression present?
Sensory loss over the anterior thigh
Reduced knee reflex ("L3, L4 kick the door")
Positive femoral stretch test
What are the features of an L4 nerve root compression?
Sensory loss over the anterior aspect of the knee
Reduced knee reflex
Positive femoral stretch test
How does an L5 nerve root compression present?
Sensory loss over the dorsum of the foot
Weakness in foot and big toe dorsiflexion
Positive sciatic nerve stretch test
How does an S1 nerve compression present?
Sensory loss posterolateral aspect of the leg and lateral aspect of the foot
Weakness in plantar flexion
Reduced ankle reflex
Positive sciatic nerve stretch test
How should disc prolapse be managed?
The patient should be carefully examined for evidence of cauda equina syndrome. If neurology is progressive, or symptoms have been present for more than 6 weeks, an MRI should be organised. Most cases will settle with conservative treatment as the herniated nucleus pulposus is resorbed and inflammation settles. Symptoms lasting more than 3 months are unlikely to resolve spontaneously and surgery to remove the herniated disc, discectomy, may be considered.
What is cauda equina syndrome?
The spinal cord terminates in an adult at L1. Below this level, the spinal canal is occupied by lower motor nerves, collectively known as the cauda equina (horses tail). The nerve roots are L2-S4 and supply most of the lower limb muscles and sensation of the perineum, including the bladder and rectal sphincters.
A large disc herniation (or mass) can compress the nerves of the cauda equina. This is cauda equina syndrome and is a surgical emergency.
What are the signs and symptoms of cauda equina syndrome?
Symptoms and signs include back pain, lower limb flaccid paralysis, loss of reflexes, paraesthesia of the perineum, loss of anal tone, faecal incontinence, painless retention of urine, overflow or stress incontinence of urine. Not all of these may be present.
Perform a full neurological exam as well as a rectal exam. If the patient is in retention, catheterise and note the residual volume in the bladder and whether the patient felt the catheter being inserted.
What are the MRI features of disc herniation?
A T2 weighted image shows the CSF as bright. The nucleus pulposus of the discs can be dark which indicates dehydration. Disc herniation shows as a narrowing of of the spinal canal.
How is cauda equina syndrome managed?
Treatment should be performed urgently and consists of surgical decompression of the spinal canal and evacuation of the herniated disc. Delaying surgery more than 24 hours significantly increases the risk of developing permanent nerve damage.
What is spinal stenosis?
In the elderly, a combination of disc degeneration and arthritis of the facet joints at the back of the spine can result in narrowing of the spinal canal, putting pressure on the spinal cord. The result is chronic leg pain, worse when walking and standing and relieved by leaning or sitting forwards. It resembles vascular claudication and may be differentiated by a normal vascular exam and a careful history. Patients often notice that there exercise tolerance improves when walking around a supermarket - they are in fact opening up the spinal canal by leaning forward on the shopping trolley!
How is spinal stenosis treated?
Treatment includes steroid epidural injections to reduce swelling, or surgical decompression of the canal (laminectomy).
What is discitis?
A serious cause of back pain, discitis is infection within the intervertebral disc. The slow rate of blood flow within the disc allows bacteria from remote sources to become lodged and multiply. The result is severe back pain, fever and raised inflammatory markers. The elderly and immunosuppressed are most at risk. If left untreated it can lead to an epidural abscess. This forms within and can compress the spinal canal.
How should discitis be investigated? How is it treated?
Investigations include inflammatory markers, blood cultures, MRI of the spine and search for the source of bacteraemia, including cardiac echo to look for vegetations. Treatment is a protracted course of antibiotics, often for several months. Presence of neurological symptoms may require surgical decompression.
What tumours commonly metastasise to the spine?
Multiple myeloma is neoplasm of plasma (antibody producing) cells and has a preference for the spine. Other common metastases are breast, prostate, lung, thyroid and kidney.
Patients may present with weight loss, general malaise and pain worse at night as well as symptoms of the primary tumour. A high index of suspicion is needed. Investigations include MRI, CT of the chest, abdo pelvis, urinary Bence Jones proteins and tumour markers.