Spinal Injuries

By admin Last updated Mar 26, 2024

Ovid: OSE Sports Medicine

Editors: Schepsis, Anthony A.; Busconi, Brian D.

Title: OSE Sports Medicine, 1st Edition

> Table of Contents > Section I – Special Issues > 8 – Spinal Injuries

Spinal Injuries

Christopher M. Bono

Marc A. Agulnick

Mark G. Grossman

The spine is commonly involved in sports injuries.
Although not the usual focus of a sports medicine practitioner, its
importance should not be overlooked. Spinal conditions can have
substantial effects on an athlete’s performance, as well as important
implications of the propensity for neurological injuries. It is the
goal of this chapter to review the essentials of spinal examination,
specific injuries of the cervical and lumbar spine, and the current
recommendations for return to sport after athletic head injuries.

SPINAL EXAMINATION

On-field Examination

Among the most crucial tasks of the
on-field physician is to decide when a potential spine injury is benign
or requires immediate stabilization and further workup.
The following features are indications
for immediate stabilization and immobilization and transfer to an
emergency department for evaluation:
- The athlete is down on the field.
- No voluntary or spontaneous movement is noted.
- Loss of consciousness has occurred.
- There are objective neurological or cognitive deficits.
- A palpable step-off is appreciated.
- Localized tenderness and pain with a high index of suspicion.
In such cases, imaging studies—such as x-rays, computerized tomography (CT), or magnetic resonance imaging (MRI)—are indicated.
The athlete needs to be immobilized carefully and securely for transfer.
The on-field examination of an injured athlete starts with evaluation of the “ABCs” (Airway, Breathing, Circulation).
- The Glasgow Coma Scale is a useful method of assessing quickly the neurocognitive status (see Table 7-3 in Chapter 7).
- The pupils should be examined for reactivity and the gaze noted for signs of ocular deviation.
A detailed neurological examination should be performed.
- The athlete should not be moved from a supine position.
- Motor strength of individual muscles or
  motions can be tested and graded (in the fully contracted or shortened
  position) in the upper and lower extremities to assess function of
  individual nerve root levels (Table 8-1 and Table 8-2).
Sensation to light touch should be graded as normal, diminished, or absent in each dermatome.
Importantly, rectal tone should be
assessed, particularly in the unconscious patient, as it may be the
only possible site of motor strength assessment. In the awake patient,
perianal sensation is a reflection of the most distal sacral nerve root
function (S2-5).

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Deep tendon reflexes should also be
tested. These include the biceps (C5), brachioradialis (C6), triceps
(C7), patella tendon (L4), and Achilles tendon (S1) reflexes.
- The bulbocavernosus reflex (assessed by
  squeezing the glans of the penis or clitoris or gently tugging a Foley
  catheter) results in involuntary contraction of the anal sphincter.
- Hyperreflexia (3 +) is an indication of upper motor neuron dysfunction, such as spinal cord compression.
- Hyporeflexia (0 or 1 +) is an indication
  of lower motor neuron dysfunction (such as compression of the cauda
  equina or peripheral nerves).
- Clonus is elicited by jerking the ankle into dorsiflexion. More than four beats are considered pathologic.
- An upgoing Babinski response is also an indication of upper motor neuron disease.
The spinous processes and paraspinal muscles should be palpated.
- This can be performed by carefully logrolling the patient from side to side, although a supine examination can often suffice.
- Importantly, a helmet should be left in place. Removing a helmet can cause harmful motion of an injured cervical spine.
  - The facemask and chin strap can, and should, be removed to allow assessment of the airway and eyes.
If a spinal injury is suspected, the athlete is then immobilized.
- A transfer board is usually used.
- The athlete is logrolled from side to side to place him/her on the board.
- Taping or strapping the head and body to
  the board is the most effective method of immobilizing the spine. A
  cervical collar can also be used.
- Once again, the helmet should stay in place.

TABLE 8-1 GRADING OF MUSCLE STRENGTH^a

Grade	Description
5	Full strength
4	Can overcome gravity with some but not full resistance
3	Can overcome gravity without resistance
2	Can move extremity with gravity eliminated
1	Visible muscle contraction without limb movement
0	No muscle contraction
^a Test in the fully contracted (or shortened) position.

TABLE 8-2 MUSCLE NERVE ROOT LEVELS

Muscle/Test	Nerve Root Level
Deltoid	C5
Biceps/wrist extension	C6
Triceps/wrist flexion	C7
Finger flexors	C8
Finger abduction	T1
Hip flexion	L1-L2
Knee extension	L2-L3
Ankle dorsiflexion	L4
Toe dorsiflexion	L5
Ankle plantarflexion	S1

Ambulatory (Office) Examination

Although many components are the same,
the in-office spinal assessment includes more detailed history and
neurological and palpatory examinations.
A history of movements (e.g., extension versus flexion) that aggravate pain should be sought.
Tenderness of the spinous processes, facet joints, sacroiliac joints, ribs, and paraspinal muscles can be differentiated.
Though it should never be performed in the acute traumatic setting, neck and back range of motion should be quantified.
In addition to the motor, sensory, and
reflex examination, the ambulatory neurologic examination should
include assessment for pathologic reflexes, such as Hoffmann’s and
inverted radial reflexes and root tension signs such as the
straight-leg raise and femoral stretch test.
Imaging studies are indicated for patients with:
- Worsening symptoms
- A progressive neurological deficit
- Symptoms that continue beyond 4 to 6 weeks
Following a general imaging protocol may be helpful.

LUMBAR SPINE INJURIES

Low back pain usually affects athletes at
some point in their career. It can be from an “overuse syndrome” or
acute trauma. Complaints may range from mild pain to severe pain after
a game or practice.
Some injuries are characteristic of
certain sports: lumbar herniated disks in weight lifters, sacral stress
fractures in runners, and spondylolysis in football players and
gymnasts.
Predominantly, axial low back pain suggests internal disc disruption from degenerative disc disease.
Predominantly, leg symptoms suggest radiculopathy from a herniated disc.
Infections, tumors, or inflammatory
arthritis are more typically suggested by nonmechanical back pain.
Other red flags are night pain, pain at rest, fever, or weight loss.
The differential diagnosis of lumbar
spine injuries in athletes can be divided into two categories: serious
acute injuries and benign and chronic injuries (Box 8-1).

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Fractures

Lumbar fractures are not uncommon with sports injuries.
The most benign of these are compression
fractures, noted by mild anterior wedging of the anterior vertebral
body. By definition, they do not involve the posterior vertebral body
and are stable fractures.
Importantly, flexion-distraction
(seatbelt type) injury should be ruled out, because this is inherently
unstable and most often surgically stabilized.
Simple compression fractures
are typically treated nonoperatively with a brace for 6 to 12 weeks. An
athlete can return to play after negative flexion-extension films,
resolution of pain, and full restoration of range of motion.
Burst fractures are higher-energy injuries that can present with or without a neurological deficit and may be stable or unstable.
- The fracture involves the posterior vertebral body and typically has canal compromise from retropulsed bone fragments.
- Nonoperative treatment can include a
  custom-molded thoracolumbar orthosis or extension cast for 12 weeks.
  Our criteria for nonoperative treatment include:
  - No neurological deficit.
  - Intact posterior ligaments (suggested by
    <25 degrees kyphosis, no interspinous process widening, no facet
    joint gapping, and confirmed by MRI inspection of the ligaments).
- Patients with evidence of posterior
  ligament injury but no neurological deficit can usually be treated by
  posterior fixation alone (e.g., pedicle screw stabilization).
  - We prefer to perform an anterior
    decompression and reconstruction for those patients with a neural
    deficit associated with retropulsed bone. Supplemental posterior
    stabilization may also be considered.
- Returning to play after treatment for a
  burst fracture is controversial. There are little to no data of any
  established criteria.
  - In our practice, return to play criteria after nonoperative treatment is similar to those described for compression fractures.
  - After surgical treatment of a burst fracture, most physicians would probably not recommend return to contact sports.

Disc Herniations and Cauda Equina Syndrome

Cauda equina syndrome (CES) is most commonly associated with a large lumbar disc herniation.
The clinical signs and symptoms of CES are:
- Saddle anesthesia (inner thighs and perineum)
- Bowel/bladder incontinence
- Variable lower extremity sensory and/or motor deficit
The treatment of CES is surgical discectomy and is best performed within 48 hours from the onset of symptoms.

Sprains and Strains

The most common cause for low back pain in athletes is a lumbar strain (muscular) or sprain (ligamentous).
They are caused by a subcatastrophic
stretch of the muscle or ligament fibers and usually result in
self-limited pain. In some cases, pain can become chronic.
A strain is associated with paraspinal
muscle tenderness and sometimes a “trigger point” spasm, whereas a
sprain demonstrates tenderness localized to the interspinous process
region.
Treatment of both sprains and strains
includes a short (1 to 2 days) period of rest, ice, and then a
stretching program directed by a trainer or physical therapist.
Return to play after a strain or sprain
is allowed once the pain has subsided and range of motion and endurance
have been restored.

Degenerative Disc Disease

The link between degenerative disc
disease (DDD) and low back pain is still unclear, although it is
commonly believed that inflammatory factors within the nucleus leak out
through annular tears (Fig. 8-1) to stimulate
nociceptive nerve endings within the annulus and dorsal root ganglion.
This is because radiographic studies have detected high rates of DDD
and other degenerative abnormalities in asymptomatic patients.
Compared with nonathletes, competitive athletes have a higher rate of degenerative changes in their lumbar spines.
- Gymnasts, weight lifters, and football players are among the most at-risk athletes.
- While competing, athletes appear to have
  a higher rate of low back pain than nonathletes; however, once retired,
  past participation in sports does not seem to be a substantial risk
  factor.
DDD is irreversible. Treatment is
directed toward decreasing the intensity and frequency of symptoms,
thus improving lumbar mechanics and muscle physiology.
- In most cases, a carefully planned and executed physical therapy program is effective.

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After treatment, the authors’ return-to-play criteria are:
- Full painless range of motion
- Ability to maintain a neutral posture during sports-specific exercises
- Full muscle strength, endurance, and control
In the rare cases that nonoperative treatment fails, an interbody fusion with or without stabilization can be performed.
- Return to play after lumbar fusion is
  controversial because clear criteria have not been established. We have
  a minimum requirement of solid radiographic fusion, in addition to
  those criteria outlined previously for nonoperative treatment.

Figure 8-1 Axial T₂-weighted MRI image of an athlete with severe low back pain and no radicular symptoms. Note the annular fissuring (white arrows),
which are thought to allow inflammatory factors from the degenerated
nucleus pulposus to “leak out” and stimulate nociceptive nerve endings
in the posterior annulus.

Spondylolysis

Stress fractures are common in athletes.
The most common region of the spine to be affected is the pars
interarticularis of the L5 (and less commonly L4) vertebra.
This is termed spondylolysis and can be a frank, nonhealed fracture or a stress “reaction” that can only be noted on an MRI or bone scan.
Importantly, an adolescent athlete with
substantial back pain longer than 3 weeks should be evaluated with
plain lumbar radiographs and a bone scan, or a single-photon emission
computed tomography scan.
- A retrospective study comparing 100
  adolescent athletes and 100 adults with acute low back pain showed that
  47% of the adolescent athletes had spondylolysis, compared with only 5%
  in the adult subjects.
- The presence and grade of spondylolysis/spondylolisthesis can influence the decision to allow return to play.
The prevalence of spondylolysis varies
from sport to sport and is highest in sports that require frequent or
sustained lumbar hyperextension maneuvers, such as diving (43%),
wrestling (30%), weight lifting (23%), throwing sports (27%), and
gymnastics (17%).
Symptoms are localized to the low back, although referred pain to the buttocks or upper thighs is not uncommon.
- Pain is exacerbated by hyperextension and relieved by flexing or squatting down.
- A single-leg hyperextension test can be useful in determining whether one or both sides have symptoms.
- Eighty-five percent of defects are detectable on a lateral lumbar film.
- CT is the most sensitive modality for
  detecting an established defect. Single-photon emission computed
  tomography scan is the most sensitive method of detecting an occult
  stress reaction.
Nonsurgical treatment of spondylolysis includes rest, brace immobilization, and pain control.
Medications include nonsteroidal anti-inflammatory drugs.
An antilordotic (Boston) brace (worn for up to 6 months) leads to resolution of symptoms in about 80% of cases.
Unilateral defects heal better than bilateral defects, though healing is not necessary for return to play.
Athletes can return to sports after nonoperative treatment of a pars defect if:
- There is no pain with extension on examination.
- The athlete remains pain-free after the brace is removed.
- Functional restoration of endurance and range of motion has been achieved.
In recalcitrant cases, surgery might be
considered. Although a single-level fusion remains the current gold
standard, a pars defect repair may be considered in some cases (Fig. 8-2).

Figure 8-2
Postoperative lateral radiograph of an athlete who underwent a pars
repair instead of a lumbar fusion for recalcitrant pain from a
spondylolytic defect of the L5 vertebra.

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CERVICAL SPINE INJURIES

Fractures and Spinal Cord Injuries

Cervical spine injuries continue to make up a large percentage of spinal injuries in sports.
Injuries range from cervical sprains to catastrophic complete spinal cord injuries (SCIs).
An estimated 10% to 15% of football players experience an injury to the cervical spine.
- The overall incidence of SCI in the high
  school and college populations is around 1 in 100,000. Most are
  incomplete with preservation of varying degrees of neurologic function.
- In an analysis of football players from
  1977 to 1989, catastrophic SCIs were secondary to fracture dislocations
  or anterior compression (burst) fractures in 33% and 22% of cases,
  respectively.
Preexisting spinal stenosis predisposes
to SCI; in such cases, athletes can sustain cord injury without bony or
ligamentous disruption.
The mechanism of injury is often direct axial load.
- Particularly in football players, the
  cervical spine is flexed (which straightens it from its usual lordotic
  posture) on impact. This decreases its ability to dissipate the load.
  With increasing loads, the spine fails in flexion, thus resulting in
  vertebral body comminution (subluxation) of facet joint dislocation.
- Experimentally, Maiman et al.
  found the average axial load to failure to be less with a straightened
  versus normolordotic posture. The greatest force applied to the spine
  was found when the load was applied to the vertex of the skull. This
  decreased as the load was moved forward on the skull.
- Torg et al.
  described the “spear tackler’s spine.” It occurs in athletes who use
  improper tackling technique, using the top of their football helmet to
  hit an opposing player head-on.
  - This is associated with an increased risk for permanent neurologic damage.
  - Affected athletes demonstrate narrowing
    of the cervical spinal canal, persistent straightening or reversal of
    the normal lordotic curve, and concomitant preexisting posttraumatic
    roentgenographic abnormalities of the cervical spine.
  - Although axial loads combined with
    flexion cause the majority of fracture dislocations of the cervical
    spine, other mechanisms can cause injuries as well.
- Rotation, extension, and shear forces
  alone or in combination have been implicated in various fracture
  patterns observed in the cervical spine.
- Although the multiple fractures
  experienced by athletes participating in contact sports such as
  football are beyond the scope of this chapter, they have led to the
  National Collegiate Athletic Association (NCAA) Football Rule Committee
  outlawing the use of one’s helmet to tackle an opponent.
Contact sports such as football, rugby, and wrestling place patients at high risk for injury.
- Most cervical spine injuries in football
  players result from hyperflexion, but other mechanisms—including
  hyperextension, rotation, and lateral bending—have been reported.
- Wrestlers commonly exhibit neck
  hyperflexion but also may endure rotational and horizontal shearing
  forces that place great stresses on the intervertebral disks, facet
  joints, and spinal ligaments.
SCI has also been documented in noncontact sports, such as diving, surfing, and gymnastics.
- These events usually result from the
  individual striking his/her head at the bottom of the pool or body of
  water, thus causing neck hyperflexion.
- Gymnasts may sustain injuries after “missed” maneuvers that result in an uncontrolled fall.
A player may be permitted to return to play after treatment of a cervical fracture in the following situations:
- The fracture is fully healed, and there is normal alignment.
- A single-level fusion has been performed below the level of C2.
- There is no residual canal compromise.
- There is no pain or neural deficit.
- There is no instability or olisthesis on flexion-extension films.
A player may not be permitted to return to play in the following cases:
- The fracture is healed in a kyphotic posture.
- A multilevel (2 or more) fusion has been performed.
- C1-C2 fusion has been performed.
- Rotatory instability is present.
- There is residual canal compromise.
- A residual neural deficit exists.
- Pain persists.
- There is evidence of instability on flexion-extension films.

Sports-specific Conditions

Transient Quadriplegia

Neurapraxia of the cervical cord, otherwise known as transient quadriplegia, is fairly common in contact sports participants.
It is characterized by bilateral burning pain, tingling, and loss of sensation in the upper and/or lower extremities.
- Burning dysesthesias and paresthesias usually occur in a glove-like distribution.
- Motor deficits can vary from mild weakness to total paralysis, depending on the extent of insult to the spinal cord.
By definition, symptoms are transient, and complete recovery usually occurs within 10 to 15 minutes but may take up to 48 hours.
Axial load with hyperextension or flexion
of the cervical spine is often the inciting event. A pincer mechanism
that theoretically causes a brief compression of the cord is thought to
play a role in the transient nature of the symptoms.
Standard radiographic evaluation of the
cervical spine is usually negative for fractures or dislocations but
incidental findings—such as congenital stenosis, spondylosis,

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Klippel-Feil syndrome, or evidence of intervertebral disk disease—may be present.
- Preexisting cervical stenosis may be a predisposing factor.
Reversible MRI spinal cord signal abnormalities have been documented.
The decision to allow an athlete to return to play after an episode of transient quadriplegia is controversial.
- Torg et al. have held that an athlete may play after one or two episodes, provided there is full neurologic recovery.
- Others are more reluctant, recommending
  no play after just one episode, particularly if there is any underlying
  spinal canal stenosis.
- From this, the term functional stenosis
  has arisen, which denotes loss of the cerebrospinal fluid space
  anterior and posterior to the spinal cord on a midsagittal MRI (Fig. 8-3), has been used as a contraindication to return to play.

Stingers and Burners

Burner syndrome is one of the most common
injuries in contact sports. The “burner” or “stinger” was named after
the pain, tingling, and burning experienced in the upper extremity of
the athlete after contact.
These injuries usually occur after the athlete strikes his head against another player, a wall, or a mat.
- The athlete experiences sudden pain,
  burning, and sometimes tingling that begins in the neck, radiates into
  the shoulder, and continues down the arm and into the hand.
- Symptoms do not follow a dermatomal
  pattern. Weakness of the supraspinatus, infraspinatus, deltoid, and
  biceps muscle are often noted, which usually presents hours to days
  after the injury.
Burners are a type of brachial plexus
injury, usually resulting from traction to the brachial plexus or
compression of the cervical root at the intervertebral foramen. Direct
impact to the plexus within the supraclavicular region has also been
reported.
- Traction injuries can occur with
  tackling. This causes sudden lateral deviation of the head away from
  the affected side and simultaneous depression of the ipsilateral
  shoulder.
  - These injuries are more frequent in high school athletes, possibly because of less developed supportive neck musculature.
- Cervical root compression occurs at the
  level of the intervertebral foramen. The foramen is dynamically
  narrowed during activities that cause cervical spinal extension,
  compression, and rotation toward the symptomatic side.
  - These injuries are more commonly seen in
    collegiate or professional athletes and present with more neck pain and
    diminished range of motion than the patients with traction injuries.
- Direct trauma to the supraclavicular region at Erb’s point can produce Burner syndrome with upper trunk deficits predominating.
- Spurling’s test (lateral flexion and
  rotation of the head toward the symptomatic side) is used to evaluate
  compression-type injuries, whereas the brachial plexus stretch test
  (lateral flexion away from the symptomatic side) can be used to
  evaluate tractiontype injuries.
Central cervical canal and foraminal
stenosis are reported as risk factors for recurrent burners. Logically,
this association has been described for compression and extension-type
injuries but not traction mechanisms.
- Athletes with a history of recurrent
  burners, associated DDD, or congenital stenosis should abstain from
  participation in contact sports.
The physician must determine whether
symptoms are from cervical cord or root pathology. This important
distinction is often made on the playing field.
- By definition, burners present with unilateral arm symptoms.
- Athletes who present with bilateral upper or any lower extremity symptoms are more likely to have had a more serious SCI.
- Focal neck tenderness or severe pain with
  motion should raise suspicion of a fracture or ligamentous injury to
  the cervical spine.
  - In these cases, the spine should be
    immobilized using a collar and backboard, and the patient transported
    to a hospital for immediate imaging.
  - Burners are self-limited syndromes that
    usually do not cause permanent sequelae. Even with this favorable
    natural history, certain restrictions should be placed on athletes
    after sustaining these injuries to prevent more severe problems in the
    future.
- Patients who are experiencing significant muscle
  
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  weakness should rest the involved extremity until symptoms improve. At
  that time, physical therapy can begin and advanced as tolerated.
- Athletes should also be started on
  year-round trapezial strengthening programs. Theoretically,
  strengthening the neck musculature may increase the shock-absorbing
  capacity of the cervical spine.
- Athletes must fulfill particular criteria before they can return to play:
  - Complete resolution of paresthesias
  - Full range of motion of the neck
  - No pain
  - Negative Lhermitte’s test (axial compression of head results in electric-like sensation down to the lower back)
  - Normal strength
Athletes who are prone to burners can use special equipment to help prevent injuries.
- Commonly used devices are thicker
  shoulder pads, neck rolls, springs, and the “cowboy collar.” They must
  fit correctly and be used with properly fitting shoulder pads to be
  effective.
Educating participants about proper
athletic technique is also important. Proper tackling and blocking
techniques, with avoidance of spearing, should be taught to young
football players as they are first learning the sport.

Figure 8-3 A sagittal T₂-weighted
MRI of an athlete with functional stenosis, noted by complete
effacement (or loss) of cerebrospinal fluid anterior and posterior to
the spinal cord. This is thought to increase the risk for SCI with
athletic trauma to the neck.

Sprain and Strain

Neck pain, or the so-called “jammed neck,” is one of the most common complaints among athletes, especially football players.
Patients can sustain an injury to the
musculotendinous unit (sprain) or paraspinal muscle itself (strain).
Therefore, one sprains a tendon but strains a muscle.
Typically, the athlete will present with localized neck pain without radiation to the arms or back.
- Athletes may have decreased cervical range of motion secondary to pain.
- Sometimes the pain may be localized to one specific cervical level.
- There are no neurologic deficits.
Treatment is based on severity and etiology.
- Generally, the use of a cervical collar and analgesic medications is continued until pain and spasm subsides.
- After the collar is removed, range-of-motion exercises can begin.
- Return to athletic participation is delayed until painless full range of motion is achieved.
- Instability may necessitate surgical stabilization to prevent future neurologic injury.

Degenerative Conditions

Disc Herniations

Acute disc herniations in contact sports are rare.
Head-on collisions or other events
leading to axial loading can result in increased intradiscal pressure.
If large enough, cord compression can manifest as either transient or
permanent quadriplegia or quadriparesis. Patients may present with
acute paralysis of all four extremities, as well as loss of pain and
temperature sensation.
- Patients may also present with anterior cord syndrome. However, acute radicular symptoms can occur alone.
MRI is the study of choice to detect a herniated disc.
Patients with persistent clinical and
radiological evidence of spinal cord compression should be offered
surgery, which may include anterior cervical diskectomy and interbody
fusion.
Radiographic evaluation of the cervical spine of football players can reveal asymptomatic cervical spondylosis.
- In one study, 7% of freshman college football players demonstrated abnormally narrowed disk spaces.
- Early degenerative changes have been attributed to years of repetitive loading from tackling.
- Severe degenerative changes—including
  foraminal stenosis, central canal stenosis resulting from posterior
  osteophytes, and the loss of normal cervical lordosis—can result in the
  classic “spear tacklers spine.”
Contraindications to returning to play after a cervical disc herniation are:
- Presence of pain (axial neck or radicular)
- Neural deficit
- Limitation of range of motion
- Any evidence of myelopathy (walking imbalance, hyperreflexia, pathological reflexes) (e.g., Hoffmann’s or inverted radial reflex)

Stenosis and Myelopathy

Narrowing or stenosis of the cervical spinal canal can predispose athletes to SCI.
Two forms of cervical stenosis have been described in athletes: developmental and acquired.
- Developmental stenosis,
  otherwise known as congenital stenosis, is present at birth and is
  characterized by shortened pedicles causing an abnormally narrow canal,
  sometimes described as funnel-shaped.
- Acquired stenosis
  is the result of reactive bony thickening and ligamentous hypertrophy
  that can result from repeated collisions in sports over time. Other
  pathoanatomic features include disc bulges, spondylolysis, and
  osteophytes.
Methods for diagnosing and quantifying cervical stenosis have been suggested.
- Sagittal canal diameter is measured on a
  standard lateral cervical spine radiograph. The measurement is recorded
  as the anteroposterior distance between the posterior aspect of the
  vertebral body and the nearest point along on the spinolaminar junction.
  - Wolfe et al. established normal parameters for this dimension.
  - The average diameters at C1, C2, and
    C3-C7 were 22 mm, 20 mm, and 17 mm, respectively. Sagittal canal
    diameters of more than 15 mm were established as normal, and diameters
    of less than 13 mm were defined as stenotic.
  - Evaluation of the sagittal canal diameter on a lateral cervical spine radiograph is limited by errors
    
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    related to magnification, roentgenographic technique, and measurement variability.
- Taking different vertebral sizes into account, Torg et al.
  derived a ratio of the anteroposterior canal diameter to the
  anteroposterior vertebral body diameter. A value below 0.8 was defined
  as spinal stenosis (Fig. 8-4).
  - Herzog et al.
    have questioned the reliability of the Torg ratio, finding it to have a
    high sensitivity but a poor positive predictive value for detecting
    clinically significant cervical narrowing.
  - Studies that have evaluated the cervical
    spines of clinically asymptomatic professional football players showed
    abnormal Torg ratios in 33% to 49%.
  - The high incidence of these abnormally
    low ratios is the result of the large vertebral body size in this
    population, with absolute dimensions of the spinal canal being
    adequately capacious for the spinal cord.
  - MRI evaluation of these players revealed adequate space available for the cord in these athletes and thus no true stenosis.
  - Currently, evaluation for functional spinal stenosis, with either MRI or CT myelogram, is becoming the new standard.
- Functional spinal stenosis is defined as obliteration of the cerebrospinal fluid cushion surrounding the cervical spinal cord.
- This method of evaluation is being used
  by many team physicians for decision making regarding athletes’ return
  to play, as well as treatment and activity modifications.

Figure 8-4 The Torg ratio is calculated by dividing the sagittal diameter of the vertebral canal (X) by the diameter of the vertebral body (Y).

Congenital Anomalies and Participation in Sports

Congenital anomalies of the cervical
spine can predispose an athlete to spinal injuries by changing the
mechanics and load dissipating properties of the cervical spine.
Congenital anomalies can occur by failure of formation or segmentation.
Klippel-Feil syndrome is secondary to failure of segmentation that may involve one or more motion segments.
- Torg and Glasgow classified Klippel-Feil syndrome into two types:
  - Type I involves a long congenital fusion (more than two segments).
  - Type II has one or two fused segments.
- As the number of fused segments
  increases, the ability of the cervical spine to dissipate loads
  decreases. More force is concentrated on the unfused motion segments,
  increasing the chance for injury in these regions with contact sports.
Failure of formation can present as odontoid agenesis, hypoplasia, or os odontoideum.
- These can result in atlantoaxial instability, which places athletes participating in contact sports at great risk for SCI.
In some instances, an athlete can have failure of formation of the atlanto-occipital junction.
- These individuals are prone to experience
  compression of the posterior columns of the spinal cord at the
  posterior margin of the foramen magnum and should be restricted from
  contact sports.
Spina bifida occulta is another congenital anomaly. It is usually an incidental finding and is asymptomatic.
- It should not usually hinder participation in athletics.

HEAD INJURIES AND CONCUSSIONS

On-field examination of a suspected head
injury should include pupillary examination and an assessment of the
level of consciousness.
- The Glasgow Coma Scale is a useful measurement.

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In cases of athletic head injuries,
treatment should include immediate immobilization (as described
previously for cervical spine injuries) and removal of the facemask,
leaving the helmet in place.
- Trendelenburg (head lower than body/heart) hypotonic intravenous fluids are contraindicated because they can cause further increases in intracerebral pressure.
Among all sports, teenage football is associated with the highest risk of head injury. Between 75% and 85% are concussions.
- A concussion is caused by temporary diminished cerebral blood flow after an impact.
- In 90% of cases, there is no loss of consciousness, thus making diagnosis difficult.
- After having one concussion, an athlete is at four times the risk for another one.
- Tables 7-2 and 7-4 in Chapter 7 cover grading and management of concussions.
The concept of the second impact syndrome is important to understand. This refers to a minor second injury after an incomplete recovery from a previous head injury.
- This can lead to massive intracerebral hypertension.
- Mortality has been reported in about 50% of cases because patients can die without any prodromal loss of consciousness.
- Second impact syndrome is associated with
  a 100% rate of permanent neurological sequelae. This highlights the
  importance of understanding the criteria for return to play after
  athletic concussions.