Athletic injuries to the atlantoaxial articulation J. WILLIAM FIELDING,* M.D., VINCENT G. FIETTI,† M.D., AND TAREK H. MARDAM-BEY,† M.D., New York, New York From the Department of Orthopaedic
Tauma
Surgery. St. Luke’s Hospital Medical Center, New York, New York
the upper cervical spine, inj uring the spinal cord, can be life-threatening and is, therefore, among the most potentially dangerous injuries an athlete can suffer. Many competitive and recreational activities from water-skiing to football to hang-gliding involve a risk of neck injury. Although the exact number of yearly injuries attributable to cervical spine trauma is unknown for many sports, some statistics are available for football-related injuries. Albright et aLl found that 32% of freshman football recruits at the University of Iowa during 1973 to 1974 had x-ray evidence of prior cervical spine injury, and that 16.3% of 104 high school football players gave a history of neck injury. Blyth and Mueller2 reported that 2.6% of 4,287 high school football players surveyed for over a 4-year period suffered a neck,injury, mostly sprains, fractures, and transient radicular symptoms in the upper extremities. Precise statistics on the incidence of fatalities and permanent para- or quadriplegia seem lacking but, although these severe injuries are infrequent, they are still of great concern to those who treat athletes. With the advent of stronger and more protective headgear in football, players might use their heads forcefully in many tackles and blocking.3Strike forces on the helmet are transmitted to the neck. Early recognition of neck trauma is generally important. An injury that leaves the athlete comatose or paralyzed on the field should be considto
*
105 East 65th Street, New York, New York. Attending physician, Department of Orthopaedic Surgery, Lenox Hill Hospital, New York.
t St. Luke’s Hospital, Amsterdam Avenue at 114th Street, New York, New York 10025. 226
ered serious, and it is suggested that neck movements by the examiner be avoided. Bolt cutters can be used to cut off football face masks but the helmet should be removed with caution to avoid neck motion. Bohlman’ reported the inadvertent production of neurologic deficits or the death of 11 of 300 patients with multiple injuries, with unrecognized neck fractures whose necks were moved during the course of emergency management. An obvious head or facial injury, particularly in a comatose athlete, should alert those rendering emergency care to rule out a &dquo;hidden&dquo; cervical spine injury. Less severe injuries, generally, require a degree of suspicion for recognition. The player complaining of pain in the neck area or radicular pain in arms or legs should be evaluated neurologically for sensory or motor deficits. Serious damage can be overlooked at the time of injury when initial complaints appear to be mild and initial evaluations appear to be negative. If neurologic deficit is found, the athlete’s neck should be immobilized until the results of appropriate tests are available. The comments thus far have been in reference to cervical spine injuries in general but, while injury at any level in the neck can cause irreversible spinal cord damage, it is in trauma to the upper cervical spine cord that potentially lethal injuries can be sustained. The following discussion is directed to types of injuries that can be sustained by athletes at the atlantoaxial level with suggestions for the mechanism of injury, symptoms, diagnosis, and management. ATLANTOOCCIPITAL DISLOCATION
This is a rarely reported injury most probably because it is usually a fatal lesion and does not
reach the care of the physicians. The lesion is usually due to a severe force to the head and should be treated by firm immobilization and early occiput to axis fusion, if indicated. POSTERIOR ATLANTOAXIAL DISLOCATION
This is
a
very
rare
lesion in which cervical 1
(C 1 )
&dquo;jumps&dquo; over the odontoid and the body of C1 lies posterior to the odontoid process. Treatment recommendation is longitudinal traction to achieve reduction followed by C1-C2 fusion, if instability can be demonstrated by flexion and extension views. TRANSVERSE LIGAMENT RUPTURE
stability is generally dependent on ligament systems. The first, the transverse ligament, and the second, composed of the remaining ligamentous structures or &dquo;accessory ligaments,&dquo; the most important of which appear to be the alar ligaments that join the tip of the odontoid to the occipital condyles. Experimental studies’ have demonstrated that Atlantoaxial two
the space between the odontoid and C 1, atlantal dens interval (ADI), is normally up to 3 mm in adults. The same experimental studies demonstrated that failure of the transverse ligament is
Fig.
1. Anterior
displacement of Cl
usually abrupt, by means of a rupture rather than stretch. With the transverse ligament ruptured,
a
3 to 5 mm. The accessory did not rupture but stretched so that, when the ADI became 10 to 12 mm, all ligaments were deficient and the cord could probably be the ADI
measures
ligaments
damaged. C1-C2 ligament deficiency may be more comthan recognized, since this lesion can potentially be fatal and routine autopsies do not usually include the upper neck. A proper understanding of the functional anatomy of the atlantoaxial joint aids in the appreciation of the importance of this injury. According to Steel’ss &dquo;rule of thirds,&dquo; the average Cring measures 3 cm and is equally occupied by the odontoid, the spinal cord, and free space. Consequently, displacement of the odontoid 10 mm backward (or Cl1 10 mm forward) suggests the possibilities of cord embarrassment. Transverse ligament rupture is thought to be the result of a flexion injury, secondary to head trauma, giving symptoms of neck pain, limited motion, spasm, etc. with or without cord signs. These symptoms may be persistent or may misleadingly resolve with time, leaving a normal physical examination, even a normal x-ray, with the mon
on
C2 due to
ligamentous disruption. 227
evidence of the lesion being an increased ADI seen only on a lateral roentgenogram. Often this increased ADI may only be seen in the flexed position, since in neutral or extension C1 may be in the normal position. The vertebral artery is held in the bony foramen transversarium of C1 and C2 and may be carried forward with the displaced C 1, resulting in decreased blood flow with symptoms of vertebral
only
artery insufficiency such as dizziness, vertigo, headaches, blurred vision, and nystagmus, etc. The athlete with transverse ligament rupture may be in danger since it was demonstrated5that a
equal to the one that ruptured the ligament can damage the accessory ligand possibly result in spinal cord injury;
force about
transverse aments an
atlantoaxial fusion may be the &dquo;conservative&dquo;
treatment for this lesion. Posterior C1-C2
using
wire and iliac bone
Fig. 228
graft,
2. Posterior
fusion,
is recommended
cervical fusion of the
with the expectation of about 50% loss of rotary motion in older patients and less in the younger ones due to compensatory motion in lower cervical segments (Fig. 1 and 2). FRACTURES OF THE ATLAS
The atlas, like the remainder of the neck, is deeply embedded in soft tissues and, short of a bullet wound or a similar penetrating injury, is inaccessible to direct trauma but susceptible to indirect violence, such as head trauma. Fractures of the atlas usually present with suboccipital headaches, neck stiffness, and limited cervical motion.’ Swallowing may be painful due to retropharyngeal swelling. Signs of spinal cord injury are uncommon because of the free space within the ring of the atlas, and the usual centrifugal direction of displacement of the fractured
fragments.
&dquo;Gallie&dquo; type. Fusion is
mature
and trabeculated.
In 1920, Jefferson’ described two main atlantal fracture types: 1. Posterior arch fractures, which are the most common and best seen on a lateral or oblique roentgenogram. Displacement is usually mild and treatment is simple, consisting mainly of cast or brace support generally leading to a satisfactory result even if fibrous union results. 2. Burst fractures (&dquo;Jefferson’s fracture&dquo;) result from a vertical blow on the head, which squeezes the atlas between the skull and axis. Because of the plane of the articular processes, the forces act laterally and can fracture the ring of the atlas as its apparent weakest point, where the arches join the lateral masses, and results in centrifugal displacement of the fractured fragments, which may be accentuated if the transverse ligament is rup-
tured.9 The typical roentgenographic findingl° is that of bilateral-lateral, usually symmetrical, overhang of the lateral masses of the atlas with bilateral increase in the para-odontoid space (Fig. 3). Treatmentll of burst fractures may require traction, since cervicocranial muscle tone and/or the
Fig. 3. Jefferson fracture. para-odontoid space.
upright position
may maintain and
even accen-
tuate the lateral
displacement of the fragments. This is followed by external plaster or brace support. If, after completion of treatment, flexionextension roentgenograms reveal significant instability, then fusion may be indicated. FRACTURES OF THE ARCH OF THE AXIS, TRAUMATIC SPONDYLOLISTHESIS OF C2, AND, HANGMAN’S FRACTURE
Fracture of the arch of the axis is a relatively rare injury that was described in victims of judicial hanging by Wood-Jones,l2 hence the term &dquo;hangman’s&dquo; fracture. The lesion is the result of a hyperextension or flexion injury where the cervicocranium (skull, atlas, and axis) hinges over the relatively fixed point (C3), leading to fracture of the arch of the axis where it joins the body with or without subluxation of C2 over C3,13 hence the
spondylolisthesis.&dquo;1’ The transand odontoid usually remain intact. ligament The lesion is often best seen on a lateral or oblique roentgenogram and may be associated with other cervical fractures. Since this fracture is usually term &dquo;traumatic verse
Note the bilateral lateral overhang of the
facets of Cl
on
C2, and bilateral widening of the 229
Fig. 4. Traumatic spondylolysthesis of C2. Note the pedicle fracture and associated anterior displacement of Cl C2. The compression fracture of the superior surface of C3 would suggest that it was produced by a flexion force.
associated with an extension type injury, which may fracture the facial bones, attention may be directed to facial injury and the traumatic spondy of C2 may be initially overlooked. Treatment of axis arch fractures is by brace immobilization if no C2-C3 subluxation can be demonstrated. However, if subluxation is seen either initially or later, then traction may be required to effect reduction, followed by a plaster immobilization for about 2 months after about 6 230
on
weeks of traction. If fusion is necessary, the anterior C2-C3 approach is preferred because stabilization by the posterior route should include C1 to C3, thus blocking C 1-C2 rotation (Fig. 4). FRACTURE OF THE ODONTOID
Odontoid fractures have been described in detail in several reviews,15-17 and recently classified into three types by Anderson and D’ Alonzo. 18 Type I is an avulsion of the upper part of the odontoid,
probably by
the attached alar
ligaments,
a rare
lesion, and stable fracture. Type II, the most commonly encountered, is a fracture through the base of the odontoid at or just below the level of the articular facets of the axis. This is often an unstable fracture, even nondisplaced Type II lesions, treated conservatively, may go on to nonunion. Anderson found that 36% of this group treated initially with immobilization failed to unite and recommended a C 1-C2 fusion. Type III is a fracture of the body of the axis; these may not be displaced and may require tomograms for clarification. A small bone chip, separated from the antero-inferior rim of the axis at the point of the rupture of the anterior longitudinal ligament, may be a clue to the presence of a type III injury. These fractures occur through cancellous bone of the axis and are usually stable and unite readily. The mechanism of injury in odontoid fractures is controversal. It is evident that a force is applied to the head and not directly to the neck. The stress forces are then transmitted to the odontoid through the joints and ligaments of the occipitoatlantoaxial complex. Both flexion and extension injuries have been reported in the literature as causing odontoid fractures. In Blockley and Purser’s series 16 of 18 patients, one-half described flexion forces and one-half hyperextension. Boh1er19 reports that 76% of his cases were due to extension forces. In their review Roberts and Wickstrom found no reason to conclude that extension was more commonly involved than flexion. At St. Luke’s Hospital, a clinical review of 20 cases showed 16 or 80% were the result of flexion or flexion rotation injuries. Four were Type III fractures and all of these were flexion injuries. Sixteen were Type II fractures and four of these were extension injuries. A fractured odontoid will usually show on the open mouth view. If no fracture is seen initially and is suspected, tomograms or stress films may help delineate the fracture line. In evaluating neck films, nonspecific radiographic signs of cervical spine trauma should be looked for, such as retropharyngeal soft tissue swelling or a widened atlanto-dental interval. The retropharyngeal space, as seen on lateral films, has been estimated to be a maximum of 5 mm in the adult at C3, and about two-thirds the width of C2 in a child. It can be artificially widened by forced expiration or swallowing. Straightening of the lordotic curve of the cervical spine is suggestive of injury, but is highly
superior
variable. Weir&dquo; has shown that 70% of normal adults will have a straightened spine, if the chin is dropped I inch from neutral. REFERENCES 1.
Albright JP, Moses JM, Dolan KD, et al: Cervical spine injuries in football. Presented at the annual meeting of American Orthopedic Society for Sports
Medicine, San Francisco, March 6, 1975 Blyth CS, Mueller FO: When and where players get hurt. The Physician and Sports Medicine, 1974, p 45 3. The Physician and Sports Medicine, 1975, p 83 2.
4. Bohlman H: Personal communication 5. Fielding JW, Cochran GVB, Lawsing JF III and Hohl M: Tears of the transverse ligament of the atlas: a clinical and biomechanical study. J Bone Joint Surg 56A: 1683, 1974 6. Steel HH: Anatomical and mechanical considerations of the atlanto-axial articulations. J Bone Joint Surg 50A: 1481, 1968 7. Rothman RH, Simeone FA: The Spine, Vol 2. Philadelphia, WB Saunders Co, 1975 8. Jefferson G: Fractures of the atlas vertebrae: report of four cases and review of those previously recorded. Br J Surg 7: 407, 1970 9. Spence KF, Decker S, Sell KW: Bursting atlantal fracture associated with rupture of the transverse ligament. J Bone Joint Surg 52A: 543, 1970 10. Fielding JW, Hawkins RJ: Roentgen diagnosis of the injured neck. 11. Sherk HH, Nicholson JT: Fractures of the atlas. J Bone Joint Surg 52A: 1017-1024, 1968 12. Wood-Jones F: The ideal lesion produced by judicial hanging. Lancet 1: 53 13. Schneider RC, Livingston KE, Cave AJE, et al: "Hangman’s fractures" of the cervical spine. J Neurosurg 22: 141-154, 1965 14. Cornish BL: Traumatic spondylolisthesis of the axis. J Bone Joint Surg 50B: 31-43, 1968 15. Aymes EW, Anderson F: Fractures of the odontoid process. Arch Surg 72: 377, 1956 16. Blockley NJ, Purser DW: Fractures of the odontoid process of the axis. J Bone Joint Surg 38B: 4, 794, 1956 17. Schatzker J, Rorabeck CH, Waddell JP: Fractures of the odontoid process of the axis. J Bone Joint Surg 392, 1971 53B: 18. Anderson LD, D’Alonzo RT: Fractures of the odontoid process of the axis. J Bone Joint Surg 56A: 1663, 1974 19. Bohler J: Fractures of the odontoid process. J Trauma 5: 386, 1965 20. Roberts, Wickstrom J: Prognosis of odontoid fractures. Acta Orthop Scand 44: 21, 1973 21. Weir DC: Roentgenographic signs of cervical injury. Clin Orthop 109: 9, 1975 22. Mouradian, Fietti, Cochran, et al: Fractures of the odontoid, in press 23. Fielding, Hawkins, Ratzan: Spine fusion for atlantoaxial instability. J Bone Joint Surg 58A: 400, 1976 24. Davis D, Bohlman H, Walker AE, et al: The pathologic findings in fatal craniospinal injuries. J Neurosurg 34: 603-613, 1971
231
Tauma
Surgery. St. Luke’s Hospital Medical Center, New York, New York
the upper cervical spine, inj uring the spinal cord, can be life-threatening and is, therefore, among the most potentially dangerous injuries an athlete can suffer. Many competitive and recreational activities from water-skiing to football to hang-gliding involve a risk of neck injury. Although the exact number of yearly injuries attributable to cervical spine trauma is unknown for many sports, some statistics are available for football-related injuries. Albright et aLl found that 32% of freshman football recruits at the University of Iowa during 1973 to 1974 had x-ray evidence of prior cervical spine injury, and that 16.3% of 104 high school football players gave a history of neck injury. Blyth and Mueller2 reported that 2.6% of 4,287 high school football players surveyed for over a 4-year period suffered a neck,injury, mostly sprains, fractures, and transient radicular symptoms in the upper extremities. Precise statistics on the incidence of fatalities and permanent para- or quadriplegia seem lacking but, although these severe injuries are infrequent, they are still of great concern to those who treat athletes. With the advent of stronger and more protective headgear in football, players might use their heads forcefully in many tackles and blocking.3Strike forces on the helmet are transmitted to the neck. Early recognition of neck trauma is generally important. An injury that leaves the athlete comatose or paralyzed on the field should be considto
*
105 East 65th Street, New York, New York. Attending physician, Department of Orthopaedic Surgery, Lenox Hill Hospital, New York.
t St. Luke’s Hospital, Amsterdam Avenue at 114th Street, New York, New York 10025. 226
ered serious, and it is suggested that neck movements by the examiner be avoided. Bolt cutters can be used to cut off football face masks but the helmet should be removed with caution to avoid neck motion. Bohlman’ reported the inadvertent production of neurologic deficits or the death of 11 of 300 patients with multiple injuries, with unrecognized neck fractures whose necks were moved during the course of emergency management. An obvious head or facial injury, particularly in a comatose athlete, should alert those rendering emergency care to rule out a &dquo;hidden&dquo; cervical spine injury. Less severe injuries, generally, require a degree of suspicion for recognition. The player complaining of pain in the neck area or radicular pain in arms or legs should be evaluated neurologically for sensory or motor deficits. Serious damage can be overlooked at the time of injury when initial complaints appear to be mild and initial evaluations appear to be negative. If neurologic deficit is found, the athlete’s neck should be immobilized until the results of appropriate tests are available. The comments thus far have been in reference to cervical spine injuries in general but, while injury at any level in the neck can cause irreversible spinal cord damage, it is in trauma to the upper cervical spine cord that potentially lethal injuries can be sustained. The following discussion is directed to types of injuries that can be sustained by athletes at the atlantoaxial level with suggestions for the mechanism of injury, symptoms, diagnosis, and management. ATLANTOOCCIPITAL DISLOCATION
This is a rarely reported injury most probably because it is usually a fatal lesion and does not
reach the care of the physicians. The lesion is usually due to a severe force to the head and should be treated by firm immobilization and early occiput to axis fusion, if indicated. POSTERIOR ATLANTOAXIAL DISLOCATION
This is
a
very
rare
lesion in which cervical 1
(C 1 )
&dquo;jumps&dquo; over the odontoid and the body of C1 lies posterior to the odontoid process. Treatment recommendation is longitudinal traction to achieve reduction followed by C1-C2 fusion, if instability can be demonstrated by flexion and extension views. TRANSVERSE LIGAMENT RUPTURE
stability is generally dependent on ligament systems. The first, the transverse ligament, and the second, composed of the remaining ligamentous structures or &dquo;accessory ligaments,&dquo; the most important of which appear to be the alar ligaments that join the tip of the odontoid to the occipital condyles. Experimental studies’ have demonstrated that Atlantoaxial two
the space between the odontoid and C 1, atlantal dens interval (ADI), is normally up to 3 mm in adults. The same experimental studies demonstrated that failure of the transverse ligament is
Fig.
1. Anterior
displacement of Cl
usually abrupt, by means of a rupture rather than stretch. With the transverse ligament ruptured,
a
3 to 5 mm. The accessory did not rupture but stretched so that, when the ADI became 10 to 12 mm, all ligaments were deficient and the cord could probably be the ADI
measures
ligaments
damaged. C1-C2 ligament deficiency may be more comthan recognized, since this lesion can potentially be fatal and routine autopsies do not usually include the upper neck. A proper understanding of the functional anatomy of the atlantoaxial joint aids in the appreciation of the importance of this injury. According to Steel’ss &dquo;rule of thirds,&dquo; the average Cring measures 3 cm and is equally occupied by the odontoid, the spinal cord, and free space. Consequently, displacement of the odontoid 10 mm backward (or Cl1 10 mm forward) suggests the possibilities of cord embarrassment. Transverse ligament rupture is thought to be the result of a flexion injury, secondary to head trauma, giving symptoms of neck pain, limited motion, spasm, etc. with or without cord signs. These symptoms may be persistent or may misleadingly resolve with time, leaving a normal physical examination, even a normal x-ray, with the mon
on
C2 due to
ligamentous disruption. 227
evidence of the lesion being an increased ADI seen only on a lateral roentgenogram. Often this increased ADI may only be seen in the flexed position, since in neutral or extension C1 may be in the normal position. The vertebral artery is held in the bony foramen transversarium of C1 and C2 and may be carried forward with the displaced C 1, resulting in decreased blood flow with symptoms of vertebral
only
artery insufficiency such as dizziness, vertigo, headaches, blurred vision, and nystagmus, etc. The athlete with transverse ligament rupture may be in danger since it was demonstrated5that a
equal to the one that ruptured the ligament can damage the accessory ligand possibly result in spinal cord injury;
force about
transverse aments an
atlantoaxial fusion may be the &dquo;conservative&dquo;
treatment for this lesion. Posterior C1-C2
using
wire and iliac bone
Fig. 228
graft,
2. Posterior
fusion,
is recommended
cervical fusion of the
with the expectation of about 50% loss of rotary motion in older patients and less in the younger ones due to compensatory motion in lower cervical segments (Fig. 1 and 2). FRACTURES OF THE ATLAS
The atlas, like the remainder of the neck, is deeply embedded in soft tissues and, short of a bullet wound or a similar penetrating injury, is inaccessible to direct trauma but susceptible to indirect violence, such as head trauma. Fractures of the atlas usually present with suboccipital headaches, neck stiffness, and limited cervical motion.’ Swallowing may be painful due to retropharyngeal swelling. Signs of spinal cord injury are uncommon because of the free space within the ring of the atlas, and the usual centrifugal direction of displacement of the fractured
fragments.
&dquo;Gallie&dquo; type. Fusion is
mature
and trabeculated.
In 1920, Jefferson’ described two main atlantal fracture types: 1. Posterior arch fractures, which are the most common and best seen on a lateral or oblique roentgenogram. Displacement is usually mild and treatment is simple, consisting mainly of cast or brace support generally leading to a satisfactory result even if fibrous union results. 2. Burst fractures (&dquo;Jefferson’s fracture&dquo;) result from a vertical blow on the head, which squeezes the atlas between the skull and axis. Because of the plane of the articular processes, the forces act laterally and can fracture the ring of the atlas as its apparent weakest point, where the arches join the lateral masses, and results in centrifugal displacement of the fractured fragments, which may be accentuated if the transverse ligament is rup-
tured.9 The typical roentgenographic findingl° is that of bilateral-lateral, usually symmetrical, overhang of the lateral masses of the atlas with bilateral increase in the para-odontoid space (Fig. 3). Treatmentll of burst fractures may require traction, since cervicocranial muscle tone and/or the
Fig. 3. Jefferson fracture. para-odontoid space.
upright position
may maintain and
even accen-
tuate the lateral
displacement of the fragments. This is followed by external plaster or brace support. If, after completion of treatment, flexionextension roentgenograms reveal significant instability, then fusion may be indicated. FRACTURES OF THE ARCH OF THE AXIS, TRAUMATIC SPONDYLOLISTHESIS OF C2, AND, HANGMAN’S FRACTURE
Fracture of the arch of the axis is a relatively rare injury that was described in victims of judicial hanging by Wood-Jones,l2 hence the term &dquo;hangman’s&dquo; fracture. The lesion is the result of a hyperextension or flexion injury where the cervicocranium (skull, atlas, and axis) hinges over the relatively fixed point (C3), leading to fracture of the arch of the axis where it joins the body with or without subluxation of C2 over C3,13 hence the
spondylolisthesis.&dquo;1’ The transand odontoid usually remain intact. ligament The lesion is often best seen on a lateral or oblique roentgenogram and may be associated with other cervical fractures. Since this fracture is usually term &dquo;traumatic verse
Note the bilateral lateral overhang of the
facets of Cl
on
C2, and bilateral widening of the 229
Fig. 4. Traumatic spondylolysthesis of C2. Note the pedicle fracture and associated anterior displacement of Cl C2. The compression fracture of the superior surface of C3 would suggest that it was produced by a flexion force.
associated with an extension type injury, which may fracture the facial bones, attention may be directed to facial injury and the traumatic spondy of C2 may be initially overlooked. Treatment of axis arch fractures is by brace immobilization if no C2-C3 subluxation can be demonstrated. However, if subluxation is seen either initially or later, then traction may be required to effect reduction, followed by a plaster immobilization for about 2 months after about 6 230
on
weeks of traction. If fusion is necessary, the anterior C2-C3 approach is preferred because stabilization by the posterior route should include C1 to C3, thus blocking C 1-C2 rotation (Fig. 4). FRACTURE OF THE ODONTOID
Odontoid fractures have been described in detail in several reviews,15-17 and recently classified into three types by Anderson and D’ Alonzo. 18 Type I is an avulsion of the upper part of the odontoid,
probably by
the attached alar
ligaments,
a rare
lesion, and stable fracture. Type II, the most commonly encountered, is a fracture through the base of the odontoid at or just below the level of the articular facets of the axis. This is often an unstable fracture, even nondisplaced Type II lesions, treated conservatively, may go on to nonunion. Anderson found that 36% of this group treated initially with immobilization failed to unite and recommended a C 1-C2 fusion. Type III is a fracture of the body of the axis; these may not be displaced and may require tomograms for clarification. A small bone chip, separated from the antero-inferior rim of the axis at the point of the rupture of the anterior longitudinal ligament, may be a clue to the presence of a type III injury. These fractures occur through cancellous bone of the axis and are usually stable and unite readily. The mechanism of injury in odontoid fractures is controversal. It is evident that a force is applied to the head and not directly to the neck. The stress forces are then transmitted to the odontoid through the joints and ligaments of the occipitoatlantoaxial complex. Both flexion and extension injuries have been reported in the literature as causing odontoid fractures. In Blockley and Purser’s series 16 of 18 patients, one-half described flexion forces and one-half hyperextension. Boh1er19 reports that 76% of his cases were due to extension forces. In their review Roberts and Wickstrom found no reason to conclude that extension was more commonly involved than flexion. At St. Luke’s Hospital, a clinical review of 20 cases showed 16 or 80% were the result of flexion or flexion rotation injuries. Four were Type III fractures and all of these were flexion injuries. Sixteen were Type II fractures and four of these were extension injuries. A fractured odontoid will usually show on the open mouth view. If no fracture is seen initially and is suspected, tomograms or stress films may help delineate the fracture line. In evaluating neck films, nonspecific radiographic signs of cervical spine trauma should be looked for, such as retropharyngeal soft tissue swelling or a widened atlanto-dental interval. The retropharyngeal space, as seen on lateral films, has been estimated to be a maximum of 5 mm in the adult at C3, and about two-thirds the width of C2 in a child. It can be artificially widened by forced expiration or swallowing. Straightening of the lordotic curve of the cervical spine is suggestive of injury, but is highly
superior
variable. Weir&dquo; has shown that 70% of normal adults will have a straightened spine, if the chin is dropped I inch from neutral. REFERENCES 1.
Albright JP, Moses JM, Dolan KD, et al: Cervical spine injuries in football. Presented at the annual meeting of American Orthopedic Society for Sports
Medicine, San Francisco, March 6, 1975 Blyth CS, Mueller FO: When and where players get hurt. The Physician and Sports Medicine, 1974, p 45 3. The Physician and Sports Medicine, 1975, p 83 2.
4. Bohlman H: Personal communication 5. Fielding JW, Cochran GVB, Lawsing JF III and Hohl M: Tears of the transverse ligament of the atlas: a clinical and biomechanical study. J Bone Joint Surg 56A: 1683, 1974 6. Steel HH: Anatomical and mechanical considerations of the atlanto-axial articulations. J Bone Joint Surg 50A: 1481, 1968 7. Rothman RH, Simeone FA: The Spine, Vol 2. Philadelphia, WB Saunders Co, 1975 8. Jefferson G: Fractures of the atlas vertebrae: report of four cases and review of those previously recorded. Br J Surg 7: 407, 1970 9. Spence KF, Decker S, Sell KW: Bursting atlantal fracture associated with rupture of the transverse ligament. J Bone Joint Surg 52A: 543, 1970 10. Fielding JW, Hawkins RJ: Roentgen diagnosis of the injured neck. 11. Sherk HH, Nicholson JT: Fractures of the atlas. J Bone Joint Surg 52A: 1017-1024, 1968 12. Wood-Jones F: The ideal lesion produced by judicial hanging. Lancet 1: 53 13. Schneider RC, Livingston KE, Cave AJE, et al: "Hangman’s fractures" of the cervical spine. J Neurosurg 22: 141-154, 1965 14. Cornish BL: Traumatic spondylolisthesis of the axis. J Bone Joint Surg 50B: 31-43, 1968 15. Aymes EW, Anderson F: Fractures of the odontoid process. Arch Surg 72: 377, 1956 16. Blockley NJ, Purser DW: Fractures of the odontoid process of the axis. J Bone Joint Surg 38B: 4, 794, 1956 17. Schatzker J, Rorabeck CH, Waddell JP: Fractures of the odontoid process of the axis. J Bone Joint Surg 392, 1971 53B: 18. Anderson LD, D’Alonzo RT: Fractures of the odontoid process of the axis. J Bone Joint Surg 56A: 1663, 1974 19. Bohler J: Fractures of the odontoid process. J Trauma 5: 386, 1965 20. Roberts, Wickstrom J: Prognosis of odontoid fractures. Acta Orthop Scand 44: 21, 1973 21. Weir DC: Roentgenographic signs of cervical injury. Clin Orthop 109: 9, 1975 22. Mouradian, Fietti, Cochran, et al: Fractures of the odontoid, in press 23. Fielding, Hawkins, Ratzan: Spine fusion for atlantoaxial instability. J Bone Joint Surg 58A: 400, 1976 24. Davis D, Bohlman H, Walker AE, et al: The pathologic findings in fatal craniospinal injuries. J Neurosurg 34: 603-613, 1971
231
