Orthopaedic IV: degenerative/paediatric disorders
Low back pain, sciatica, (see Wraighte, CROSS REFERENCES). When symptoms occur,
they are usually the result of disc herniation and osteophyte for-
cervical and lumbar mation at these levels, causing central canal and neural foramenal
stenosis. With time, the osteophytes limit motion, producing
spondylosis relatively stiff motion segments at these levels. Compensatory
hypermobility then occurs at the more rostral levels, often evi-
dent on plain lateral radiograph as antero- and posterolisthesis.
Nicholas W M Thomas In older patients who are symptomatic, motion is at the C3/4
and C4/5 levels and results in segmental instability. This may
occur ± significant disc herniation and osteophytic changes.
There is a reduction in the diameter of the spinal canal (spinal
canal stenosis) and the dimensions of the neural foramina (lateral
Abstract recess stenosis) that causes impingement or compression of the
This contribution discusses the features and management of back pain, neural structures, which may have a non-dynamic and dynamic
cervical spondylotic myelopathy, sciatica and neurogenic claudication. component, causing symptoms (Figure 1).
Keywords back pain; cervical spondylotic myelopathy; sciatica; Lumbar spine
neurogenic claudication Similar degenerative changes occur to those in the cervical spine.
These are most prominent at the L4/5 and L5/S1 levels; >90%
of significant herniations of the disc with neural compression
Spondylosis is a progressive, age-related degenerative change of occur at these levels. The range of motion of the lumbar seg-
the spine. The mid-cervical and lower lumbar regions are partic- ments is less than in the cervical spine and hypermobility is less
ularly affected because of the distribution of mechanical stresses common, unless there is a slip of one vertebral body on another
due to spinal motion and loading of the spinal segments when (spondylolisthesis).
in the erect posture. These changes are usually asymptomatic
apart from increasing stiffness and reduced mobility of the spine.
Pathophysiology
When symptomatic, clinical features include axial spinal pain
(neckache, backache) or neural compression (radiculopathy, Intervertebral discs
myelopathy, see below). Anatomy: the intervertebral disc comprises the nucleus pul
posus surrounded by the annulus fibrosus. These structures are
attached rostrally and caudally to the adjacent vertebral bodies
Natural history
by cartilaginous end plates. The annulus consists of multiple
The normal curvature of the adult spine comprises a cervical lamellae that are high in collagen content; the lamellae resist ten-
and lumbar lordosis and a thoracic kyphosis. During motion, sile stresses. The hydrophilic proteoglycan content of the nucleus
oscillation of the axial components of the spine allows for the pulposus generates a high osmotic pressure (see Denman, CROSS
absorption of imparted stresses. The discs, vertebral bodies, facet REFERENCES), which exerts a radial stress against the annulus
joints, muscles and ligaments contribute to the maintenance of and endplates. This in turn generates a circumferential stress in
the spine in the ideal biomechanical posture. the annular lamellae. A high intradiscal pressure is required to
There are dynamic changes between segments with age, lead- develop the radial stress, and subsequent circumferential stress
ing to altered spinal alignment, with a loss of lordosis in the cervi- prevents disc bulging (Figure 2).
cal and lumbar regions and a progressive kyphosis in the thoracic
region. There may be neural impingement on the spinal cord or Disc degeneration: radial and circumferential annular fissures
nerve roots from degenerate disc, bone or ligament, which may develop with ageing, and the endplates fracture (Schmorl’s
result in the development of symptoms. nodes) and calcify, the latter resulting in compromise of the
blood supply. There is increased anaerobic metabolism, cellular
Cervical spine necrosis and loss of intradiscal water content. If there is dis-
There is a wide range of motion in all planes because of the ruption of the annulus or nucleus, there is a reduction in the
obliquity of the facet and uncovertebral joints. Stability is largely intradiscal pressure, a reduced circumferential annular stress
conferred by the supporting ligaments and muscles. Motion is and consequent disc bulging. The posterolateral annulus is the
predominant at the C5/6 and C6/7 levels between the ages of weakest region and predisposes to disc herniation (Figure 3).
20 years and 40 years. Disc dehydration, loss of disc height and The posterior longitudinal ligament usually prevents a direct
herniation are most pronounced at these levels. The movement posterior herniation.
also results in stripping of the periosteum from the vertebral
body, with new bone being laid down to form an osteophyte Facet joints
In addition to disc degeneration, there are changes within the
facet joints (and also the uncovertebral joints in the cervical
Nicholas W M Thomas FRCS(Glas) FRCS(Eng)SN is a Consultant spine) that cause hypertrophy of the joints and surrounding
Neurosurgeon at King’s College Hospital, London. Conflicts of interest: capsules and ligaments. Nociceptive fibres are present in the
none declared. supra- and interspinous ligaments, ligamenta flava, facet joints
SURGERY 25:4 155 © 2007 Elsevier Ltd. All rights reserved.
Orthopaedic IV: degenerative/paediatric disorders
a MRI of the spine showing generalized narrowing of the spinal canal with ligamentous buckling (arrow). b Radiograph of the neck showing
slip at the C4/5 level (arrow).
Figure 1
and capsules, and the peripheral annular fibres. Any of these a specific pathoanatomical diagnosis because of variable symp-
structures may be the source of back pain. The term ‘discogenic’ toms and signs, difficulty in localizing the pain, and imaging that
pain is used if the pain arises from the disc. reveals only degenerative changes. These cases are described as
‘musculoligamentous injuries’ (arising from the many structures
in the back described above) and 90% settle within one month.
Clinical syndromes
The conditions discussed below must be excluded when assess-
Back pain ing back pain.
Back pain is one of the leading symptoms prompting a visit to
a physician in the western world and contributes significantly Underlying systemic or local disease
to the economy because of absence from work and registered Malignant disease (primary and metastatic) accounts for
disability. 0.7% of patients seen in primary care with back pain, and 80%
Assessment should be analysed in the context of symptoms of patients are >50 years of age. Other factors to consider are
and signs; 20–30% of asymptomatic people have evidence of a systemic symptoms and worsening back pain on recumbency.
herniated disc, often with neural impingement, and 5% have Spinal infections are usually haematogenous in origin and a
significant canal stenosis. Seventy percent of adults have low history of intravenous drug abuse is identified in about 40% of
back pain at some time in their life, with 14% having an episode patients. Tuberculosis should be considered in patients of Asian
lasting >2 weeks. About 85% of these cases cannot be given or African origin, although it is not exclusive to these groups.
SURGERY 25:4 156 © 2007 Elsevier Ltd. All rights reserved.
Orthopaedic IV: degenerative/paediatric disorders
Osteoporosis (see Crosbie, CROSS REFERENCES) commonly
Intervertebral disc causes compression fractures and most patients do not have a
history of trauma. Age (particularly in post-menopausal women)
Nucleus generates a radial and long-term use of corticosteroids are factors.
stress against the annulus and Spinal fracture – a history of trauma is usually elicited.
endplates
Evidence of neural compression
Radiculopathy – in 1.5% of cases of low back pain, there
is an associated radiculopathy due to a herniated disc, and this
presents as sciatica. Radiculopathy describes pain in the distribu-
tion of the nerve root (typically a sharp pain down the lateral or
posterior aspect of the leg to the foot or ankle), dermatomal sen-
sory loss, and possible muscle weakness relating to the particular
root involved. The peak incidence of sciatica is in the 30–55 age
group.
Cauda equina syndrome causes sphincter disturbance (urin
ary retention, incontinence, saddle anaesthesia), often bilat-
eral sciatica, significant motor weakness (often involving more
than one motor root), low-back pain, and sexual dysfunction.
Lamellae of annulus This usually results from a large, centrally placed ruptured
generates a circumferential stress disc (usually at the L4/5 level) and constitutes 1–2% of all
operated discs. Urgent removal of the disc and decompression
of the neural structures is indicated to preserve neurological
Figure 2
function.
Neurogenic claudication is caused by spinal stenosis and
presents as aching in the legs when walking or standing. Double
compression of the nerve root, within the thecal sac or the root
canal, is an important factor in nerve physiology, impaired
blood flow and subsequent generation of pain. Flexion relieves
symptoms by increasing the canal diameter and patients may
experience fewer problems when sitting. Neurological deficit is
uncommon and the differential diagnosis includes peripheral
vascular disease.
Social and/or psychological reasons may prolong or embellish
symptoms and signs (particularly in cases involving litigation).
The chance of returning to work is virtually zero if a patient has
been off work for more than one year with back pain.
Imaging
MRI should be requested if symptoms have persisted for
>6 weeks and if there are no suspicious clinical indicators. MRI
has high resolution and avoids the irradiation associated with
CT. CT occasionally must be used if there are contraindications
to MRI (e.g. cardiac pacemaker, ferrous metal implants, foreign
bodies).
CT myelography is invasive, involves irradiation, and iden-
tifies intradural structures less satisfactorily. Radiographs show
unexpected findings in only 1 in 2500 adults aged <50 years.
Lytic lesions may be evident on radiograph only after 60% bone
loss, and should not be routinely used for back pain.
MRI and discography have been used to investigate patients
with ‘discogenic’ pain. A discogram involves the percutaneous
injection of contrast dye into the disc under radiographic guid-
ance in an attempt to reproduce the pain. The proponents of
discography suggest that this gives useful information about the
Figure 3 MRI of the lumbar spine showing disc herniation through a potential internal disruption of the disc, but studies have shown
ruptured annulus (arrow). significant false-negative and false-positive results.
SURGERY 25:4 157 © 2007 Elsevier Ltd. All rights reserved.
Orthopaedic IV: degenerative/paediatric disorders
Cervical spondylotic myelopathy The surgical options for treatment of a posterolateral disc
A myelopathy results from compression of the spinal cord. herniation are described below.
Pronounced symptoms include:
• numbness, clumsiness and weakness of the hands Transcanalicular approaches
• difficulty with walking because of stiffness, weakness and Microdiscectomy is the ‘gold standard’. Using an operating
sensory impairment in the legs microscope, a small posterior lumbar incision is made, the liga-
• difficulty with bladder control. mentum flavum removed (± additional foramenotomy) and
In 75% of cases, there is progression of symptoms gradually the herniated disc fragment removed after identification of the
(75%) or stepwise (25%). In others, the presentation is with an nerve root and theca. Usually, the disc space is entered and
initial phase of deterioration which may remain stable for many additional disc fragments are removed. Success rates of 90–95%
years. at 10–15 years have been reported, with a reoperation rate of
5–15%. Complications include infection, haematoma, leak of
Imaging: the first-line investigation is MRI. Plain radiographs in cerebrospinal fluid and nerve damage.
flexion and extension determine if there is abnormal movement. Laminectomy – a full laminectomy, with removal of the
spinous process and the medial half of each facet, is required
only if the disc is large. It is occasionally needed if cauda equina
Treatment
syndrome is present.
Back pain
Most patients with acute musculoligamentous pain require short- The extracanalicular intradiscal approaches are automated
term treatment with NSAIDs, muscle relaxants, along with activ- percutaneous lumbar discectomy (APLD), percutaneous endo-
ity modification. Symptoms are short-lasting in most cases and scopic discectomy, laser discectomy and chemonucleolysis.
are treated non-surgically. Intradiscal electrothermal therapy The intradiscal procedures were developed to achieve minimal
involves the insertion of a wire to denervate the annulus, but intervention and to avoid scarring around the nerve root. The
long-term results are not promising. approach is lateral to the canal and direct into the disc space.
The diagnosis and subsequent surgical treatment of patients These techniques are more contentious, are generally used
with little or no radicular symptoms is more complex and con- less regularly, and rely upon decompressing the nucleus and
troversial. This contrasts with patients who have sciatica and thereby improving disc compliance. The disadvantage is that
neurogenic claudication. the true disease (often posterolateral disc herniation) cannot be
addressed easily.
Fusion surgery: anterior or posterior (or both) interbody fusion APLD uses a reciprocating suction cutter which is introduced
techniques are considerable surgical undertakings. These tech- percutaneously into the disc. Success rates vary from 55% to
niques are widely used and long-term ‘good’ or ‘satisfactory’ 85% for small-disc herniations. There are also more recent disc
outcomes of up to 75% have been reported. There are no good- decompression devices. The nucleus can be removed by endo-
quality randomized prospective data to clearly establish the scopic discectomy (allowing direct visualization) or laser disc
superior benefit of surgery over non-surgical treatment. There is ectomy and, as with all the intradiscal techniques, works best in
a more recent development of a minimally-invasive sacral screw a small-disc herniation that has not breached the outer annulus
to fixate and fuse L5/S1 and L4/5 disc spaces. (contained disc).
Chemonucleolysis involves the injection of chymopapain, a
Disc replacement: the concept of preserving segmental motion proteolytic enzyme. The technique is used very rarely because
is not new and this technique is gaining wider acceptance due of associated complications and morbidity (i.e. back pain,
to the development of newer prostheses to replace the nucleus anaphylaxis, discitis and neurological problems including
(‘partial-disc replacement’) or the whole disc. The full-disc transverse myelitis).
arthroplasty technique appears to most effectively maintain
spinal intersegmental motion while addressing the presumed Neurogenic claudication
source of pain (nociceptive fibres to the annulus). The results of Surgery is the only treatment that alters the anatomical cause
studies over ten years suggest that this technique is at least as of the symptoms. A lumbar laminectomy with undercutting of
good as fusion surgery and avoids compensatory hypermobility the facets or multiple laminotomies to decompress the roots in
and degeneration at a level adjacent to a fused segment. Good- the lateral recesses results in a good outcome for 55–87% of
quality randomized data comparing this with non-surgical treat- patients.
ment are not available.
Cervical spondylotic myelopathy
Sciatica Once the symptoms of cervical spondylotic myelopathy have
Eighty-five percent of patients with sciatica settle with non-sur- developed, complete remission occurs very rarely and surgical
gical treatment within six weeks. There are no data to strongly results may be disappointing. The main aim of surgery is to
support bed rest for >48 hours, local joint injections, epidurals, prevent further neurological deterioration, although about 60%
transcutaneous nerve stimulation, radiofrequency facet denerva- of patients will appreciate some improvement of symptoms.
tion, lumbar supports, traction or acupuncture. Surgical approaches may be posterior (laminectomy) or
Surgery is considered if conservative measures fail. Between anterior (anterior cervical discectomy, anterior foramenotomy).
5% and 10% of patients with sciatica eventually require surgery. There are few studies comparing the anterior versus the posterior
SURGERY 25:4 158 © 2007 Elsevier Ltd. All rights reserved.
Orthopaedic IV: degenerative/paediatric disorders
approach and neither is clearly superior. Fixation may also be A posterior approach is indicated if there is posterior ligamental
required if there is a dynamic element to the disease. buckling, and is often desirable if there are multiple levels of com-
pression. The main disadvantage of a laminectomy is that it is poten-
An anterior approach is indicated if there is anterior disease tially destabilizing (hence preoperative flexion/extension radiographs
(herniated disc or osteophyte). The Cloward anterior cervical dis- should be taken to ensure that abnormal motion is absent). Lateral
cectomy describes partial removal of the disc and insertion of a mass screw fixation may also be needed if instability is present. ◆
dowel of bone from the iliac crest; this procedure is now rarely
done. The Smith–Robinson technique involves removal of the
whole disc with decompression of the lateral recesses with no
graft.
More recent developments include the avoidance of taking an Cross references
iliac crest graft (painful and has significant associated morbid- Crosbie D, Reid DM. Osteoporosis. Surgery 2006; 24(11): 386–7.
ity) by using bone allograft (see Marsh, CROSS REFERENCES) Denman ES. Osmolarity and partitioning of fluids. Surgery 2005;
or a synthetic spacer (‘cage’) filled with coral, hydroxyapatite 23(6): 190–4.
or endplate bone harvested at the time of surgery. Insertion of Marsh JL. Principles of bone grafting: non-union, delayed union.
a reinforced carbon fibre or titanium spacer has the theoretical Surgery 2006; 24(6): 207–10.
advantage of maintaining cervical lordosis and the height of the Wraighte PJ, Scammell BE. Principles of fracture healing.
neural foramen. Surgery 2006; 24(6): 198–206.
SURGERY 25:4 159 © 2007 Elsevier Ltd. All rights reserved.
