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Odontoid fracture in a nine-month-old infant
Surg Neurol 1985;24:529-32
529
O d o n t o i d Fracture in a N i n e - m o n t h - o l d I n f a n t S c o t t J. S a v a d e r , M . D . , C a r l o s M a r t i n e z , M . D . , a n d F. R e e d M u r t a g h , M . D . Department of Radiology, University of South Florida College of Medicine, Tampa, Florida
Savader SJ, Martinez C, Murtagh FR. Odontoid fracture in a ninemonth-old infant. Surg Neurol 1985;24:529-32.
A type 2 odontoid fracture in a nine-month-old infant is presented. To the best of our knowledge, this case has the youngest reported patient with this type of injury having occurred by a mechanism other than direct trauma at birth. The purpose of this communication is to review odontoid fractures in the pediatric age group. KEYWORDS: Odontoid fracture; Axis fracture; Dens fracture; Cervical injury; Os odontoideum; Infancy
Although odontoid fractures have been reported in all age groups, most reports focus on the adult patient. The pediatric age group, especially those under 7 years of age, should probably be considered as a separate entity. In the adult population, odontoid fractures occur in about 7 - 1 4 % of cases of cervical spine injury, based on reports from multiple series [1,3,4,9,10]. In children up to 7 years of age, odontoid fractures are much more common, accounting for up to 75% of cervical spine injuries [12]. This difference probably reflects the greater vulnerability of the odontoid process in the pediatric age group secondary to incompleteness of the ossification process at the base of the odontoid. The most common mechanism of odontoid fracture in the pediatric age group, based on a search of the literature, appears to be either a fall of some type, often from a low household object, or a blow to the occiput. Although this did not apply to our case, automobile accidents seem to be a relatively uncommon mechanism of injury in this young age group, whereas in the adult population it is common. Case Report
A nine-month-old infant girl was strapped into a portable seat facing forward in the back seat of an automobile. The car was involved in an accident, the details of which were unknown. Upon initial presentation to
Address reprint requests to: Scott Savader, M.D., USF College of Medicine, 12901 N. 30th Street, Box 17, Tampa, Florida 33612. Co) 1985 by Elsevier Science Publishing Co., lnc,
the emergency room, the infant exhibited no external signs of trauma. She was irritable, and had a mild fever and positive Brudzinski sign on the right, but her neck was supple. N o radiographs were taken and the child was discharged. The mother returned with the child 3 days later and complained that she had been very irritable since the accident. Examination revealed stiffness of her neck but no other neurologic signs or symptoms. X-ray films of the cervical spine revealed an anteriorly angulated type 2 odontoid fracture (Figure 11 which was confirmed by computed tomography scanning (Figure 2A and B) and tomography (Figure 3). The patient was admitted and placed in cervical hyperextension using a neck brace. Repositioning of the neck brace was required and achieved nearly complete anatomic alignment as shown by the subsequent tomogram (Figure 4). At no time during her admission were any neurological signs or deficits noted. The patient was discharged 8 days after admission with the cervical brace in place and was scheduled for subsequent observation. The patient was closely observed and 3 months after her discharge, still exhibited no neurological deficits. She was given a custom soft collar after plain films of the cervical spine showed progressive healing with satisfactory alignment of the odontoid process. Six months after the accident, the patient continued to exhibit normal neurological function and plain cervical extension and flexion x-ray films showed adequate alignment and healing of the fracture. The soft collar was discontinued and the patient was scheduled for examination in 1 year. Discussion Odontoid fractures have been categorized by Anderson and D'Alonzo [2] into three types: type 1 fractures consist o f an oblique avulsion fracture o f the most distal aspect of the dens; type 2 fractures are through the base of the odontoid process at its union with the base of the axis; type 3 fractures are through the cancellous bone of the body of the axis, resulting in a free fragment that consists of part of the body of C-2 with the odontoid process attached. Until the age of 4 - 7 years, and in some cases during adolescence, a rudimentary cartilaginous disk (exhibit009(I-~(119/85/$~, ~,(1
530
Surg Neurol 1985;24:529-32
Savader et al
A
Figure 1. Lateral C spine shows the anteriorly displaced and angulated odontoid process. Note the prominent prevertebral soft tissue swelling.
ing no nucleus pulposus) separates the dens from the body of the axis. At this time, bony growth from the dens proceeds inferiorly and from the body of C-2 superiorly until the two are united into a single unit [ 5,11]. It is through this relatively fragile cartilaginous plate that almost all pediatric odontoid fractures occur. Sherk et al [13] reported on 12 pediatric patients under the age o f 6 years. All o f the fractures were o f type 2 and situated at the uncalcified plate lying between the dens and the body o f C-2. They cite an additional 24 cases from 12 reports on pediatric odontoid fractures and again in this group, whose average age was 4 years, all the fractures were through the cartilaginous plate. Types 1 and 3 fractures are very rare in this age group. Although the adult population tends to follow this trend, types 1 and 3 fractures do occur more often. Anderson and D'Alonzo's study [2] o f 49 adults noted two (4.1%) type 1 fractures and 15 (30.6%) type 3 fractures, with the remaining 32 (65.3%) fractures consisting o f the type 2 variety. Maimen and Larson's study [8] o f 51 adult patients noted no type 1 fractures, two (4%) type 3 fractures, and 49 (96%) type 2 fractures. Type 1 fractures are considered the least severe o f the odontoid fractures. The apical and alar ligaments, which normally secure the tip of the dens to the occiput, act to hold any avulsed fragments o f bone in proper orientation to allow for efficient healing. These fractures are stable, without risk o f atlantoaxial subluxation, and
i~~ ~i
B
Figure 2. (A) A computed tomography scan with sagittal reconstruction confirms the fractured odontoidprocess is anteriorly angulated. (B) A computed tomography scan shows the rounded baseof the dens with thefractured distal portion lying just anterior.
heal well in about 6 weeks with simple immobilization [10]. Type 3 fractures are more extensive than type 1 fractures, but because of the large cancellous surface o f bone exposed by the injury, they too are relatively stable and without risk of atlantoaxial subluxation. Nonunion is seen in about 8 % of those patients treated with traction (to allow for realignment) followed by immobilization. Wiring and fusion are performed only if union of the fracture does not occur. Seven weeks was the average healing time noted by Ryan and Taylor [ 10].
Odontoid Fracture
Surg Neurol 1985;24:529-32
531
Figure 3. A lateral midline tomogram through the cervical spine shows the fractured odontoid process angulated about 40 °.
T y p e 2 fractures are considered to be the most severe o f the odontoid fractures. Fractures o f this type are unstable and carry a high risk o f atlantoaxial subluxation with subsequent injury to the spinal cord or even death. Despite the severity of this injury, pediatric patients who present without neurologic deficit tend to do very well after reduction and immobilization with either a halo cast or minerva jacket. Sherk et al [13] experienced a 100% rate o f healing without growth disturbances or subsequent neurologic symptoms in 12 pediatric patients under the age of 6 years treated in this fashion. This is possibly due to the fact that this injury is similar to a separation o f the epiphyseal plate (Salter type 1 fracture) which tends to heal well in other locations. The adult population does not fare as well with this type of injury. Anderson and D'Alonzo [2] noted a 3 6 % rate of nonunion in conservatively treated adults with type 2 fractures. Ryan and Taylor's group of nine conservatively treated adult patients had a nonunion rate of 2 2 % after an average of 8 weeks of immobilization using either a halo cast or minerva jacket [10]. Wiring and fusion are considered the treatment of choice in both the adult and pediatric age groups should nonunion of the fracture occur after a trial o f conservative therapy.
Figure 4. Tomogram after placement of a brace shows near-complete anatomh alignment of the odontoid process.
Os o d o n t o i d e u m is an anomaly of the axis in which the dens is separated transversely from the base of C2. T h e distal portion appears as a small rounded ossicle separate from the base of C-2 and attached to the atlas by the transverse ligament [7]. This condition, originally thought to be congenital in origin, results in an anatomical arrangement similar to the type 2 odontoid fracture. T h e ossicle, which has no connection to the axis, results in a joint with inherent atlantoaxial instability. This joint is capable of subluxation with even minor trauma to the neck or occiput. "Acquired" os o d o n t o i d e u m following cervical trauma has also been recorded [6,7,14]. In these cases, a normal odontoid process was documented after initial injury to the cervical spine. Years later, after the spontaneous d e v e l o p m e n t of neurological symptoms, these patients demonstrated a free, rounded ossicle posterior to the anterior arch of C- 1 indistinguishable from
532
Surg N e u r o l 1985;24:529-32
a "congenital" os odontoideum. In these cases, it is thought that the initial injury resulted in an unrecognized fracture through the cartilaginous plate between the distal portion of the dens and the body of C-2. Subsequent resorption of this plate, possibly secondary to a compromised blood supply, and remodeling of the dens resulted in an os odontoideum indistinguishable on followup radiographs from the "congenital" variety. Undisplaced fractures of the odontoid process may be difficult to detect on a plain x-ray film of the cervical spine. Frequently, a true lateral view is difficult to obtain, and subtle angulation of the odontoid may be missed. In cases where the patient presents with persistent neck pain and neurological symptoms, or both, a lateral midline tomogram of the upper cervical spine should be considered, inasmuch as this offers the greatest reliability in demonstrating fractures of the odontoid process.
The authors wish to express their special thanks to Ms. Rhonda Kaye Tuttle for her time and effort in the preparation of this manuscript.
References 1. Amyes EW, Anderson FM. Fractures of the odontoid process: report of sixty-three cases. Arch Surg 1956;72:377-93.
Savader et al
2. Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg 1974;56-A: 1663-74. 3. Bohler J. Fractures of the odontoid process. J Trauma 1965; 5:386-91. 4. Crooks F, Birkett AN. Fractures and dislocations of the cervical spine. Br J Surg 1944;31:252-65. 5. Dyck P. Os odontoideum in children: neurological manifestations and surgical management. J Neurosurg 1978;2:93-9. 6. Fielding WJ, Griffin PP. Os odontoideum: an acquired lesion. J Bone Joint Surg 1974;56-A:187-90. 7. Hawkins RJ, FieldingJW, Thompson WJ. Os odontoideum: congenital or acquired. J Bone Joint Surg 1976;58-A:4 l 3-4. 8. Maimen DJ, Larson SJ. Management of odontoid fractures. J Neurosurg 1982; 11:471-6. 9. Nachemson A. Fracture of the odontoid process of the axis: a clinical study based on 26 cases. Acta Orthop Scand 1959;29:185-217. 10. Ryan MD, Taylor TFK. Odontoid fractures: a rational approach to treatment. J Bone Joint Surg 1982;64-B:416-21. l 1. Seimon LP. Fractures of the odontoid process in young children. J Bone Joint Surg 1977;59-A:943-7. 12. Sherk HH. Fractures of the atlas and odontoid process. Orthop Clin N Am 1978;9:973-9. 13. Sherk HH, NicholsonJT, Chung YMK. Fractures of the odontoid process in young children. J Bone Joint Surg 1978;60-A:921-4. 14. Stillwell WT, Fielding WJ. Acquired os odontoideum; a case report. Clin Orthop Relat Res 1978;135:71-3.
529
O d o n t o i d Fracture in a N i n e - m o n t h - o l d I n f a n t S c o t t J. S a v a d e r , M . D . , C a r l o s M a r t i n e z , M . D . , a n d F. R e e d M u r t a g h , M . D . Department of Radiology, University of South Florida College of Medicine, Tampa, Florida
Savader SJ, Martinez C, Murtagh FR. Odontoid fracture in a ninemonth-old infant. Surg Neurol 1985;24:529-32.
A type 2 odontoid fracture in a nine-month-old infant is presented. To the best of our knowledge, this case has the youngest reported patient with this type of injury having occurred by a mechanism other than direct trauma at birth. The purpose of this communication is to review odontoid fractures in the pediatric age group. KEYWORDS: Odontoid fracture; Axis fracture; Dens fracture; Cervical injury; Os odontoideum; Infancy
Although odontoid fractures have been reported in all age groups, most reports focus on the adult patient. The pediatric age group, especially those under 7 years of age, should probably be considered as a separate entity. In the adult population, odontoid fractures occur in about 7 - 1 4 % of cases of cervical spine injury, based on reports from multiple series [1,3,4,9,10]. In children up to 7 years of age, odontoid fractures are much more common, accounting for up to 75% of cervical spine injuries [12]. This difference probably reflects the greater vulnerability of the odontoid process in the pediatric age group secondary to incompleteness of the ossification process at the base of the odontoid. The most common mechanism of odontoid fracture in the pediatric age group, based on a search of the literature, appears to be either a fall of some type, often from a low household object, or a blow to the occiput. Although this did not apply to our case, automobile accidents seem to be a relatively uncommon mechanism of injury in this young age group, whereas in the adult population it is common. Case Report
A nine-month-old infant girl was strapped into a portable seat facing forward in the back seat of an automobile. The car was involved in an accident, the details of which were unknown. Upon initial presentation to
Address reprint requests to: Scott Savader, M.D., USF College of Medicine, 12901 N. 30th Street, Box 17, Tampa, Florida 33612. Co) 1985 by Elsevier Science Publishing Co., lnc,
the emergency room, the infant exhibited no external signs of trauma. She was irritable, and had a mild fever and positive Brudzinski sign on the right, but her neck was supple. N o radiographs were taken and the child was discharged. The mother returned with the child 3 days later and complained that she had been very irritable since the accident. Examination revealed stiffness of her neck but no other neurologic signs or symptoms. X-ray films of the cervical spine revealed an anteriorly angulated type 2 odontoid fracture (Figure 11 which was confirmed by computed tomography scanning (Figure 2A and B) and tomography (Figure 3). The patient was admitted and placed in cervical hyperextension using a neck brace. Repositioning of the neck brace was required and achieved nearly complete anatomic alignment as shown by the subsequent tomogram (Figure 4). At no time during her admission were any neurological signs or deficits noted. The patient was discharged 8 days after admission with the cervical brace in place and was scheduled for subsequent observation. The patient was closely observed and 3 months after her discharge, still exhibited no neurological deficits. She was given a custom soft collar after plain films of the cervical spine showed progressive healing with satisfactory alignment of the odontoid process. Six months after the accident, the patient continued to exhibit normal neurological function and plain cervical extension and flexion x-ray films showed adequate alignment and healing of the fracture. The soft collar was discontinued and the patient was scheduled for examination in 1 year. Discussion Odontoid fractures have been categorized by Anderson and D'Alonzo [2] into three types: type 1 fractures consist o f an oblique avulsion fracture o f the most distal aspect of the dens; type 2 fractures are through the base of the odontoid process at its union with the base of the axis; type 3 fractures are through the cancellous bone of the body of the axis, resulting in a free fragment that consists of part of the body of C-2 with the odontoid process attached. Until the age of 4 - 7 years, and in some cases during adolescence, a rudimentary cartilaginous disk (exhibit009(I-~(119/85/$~, ~,(1
530
Surg Neurol 1985;24:529-32
Savader et al
A
Figure 1. Lateral C spine shows the anteriorly displaced and angulated odontoid process. Note the prominent prevertebral soft tissue swelling.
ing no nucleus pulposus) separates the dens from the body of the axis. At this time, bony growth from the dens proceeds inferiorly and from the body of C-2 superiorly until the two are united into a single unit [ 5,11]. It is through this relatively fragile cartilaginous plate that almost all pediatric odontoid fractures occur. Sherk et al [13] reported on 12 pediatric patients under the age o f 6 years. All o f the fractures were o f type 2 and situated at the uncalcified plate lying between the dens and the body o f C-2. They cite an additional 24 cases from 12 reports on pediatric odontoid fractures and again in this group, whose average age was 4 years, all the fractures were through the cartilaginous plate. Types 1 and 3 fractures are very rare in this age group. Although the adult population tends to follow this trend, types 1 and 3 fractures do occur more often. Anderson and D'Alonzo's study [2] o f 49 adults noted two (4.1%) type 1 fractures and 15 (30.6%) type 3 fractures, with the remaining 32 (65.3%) fractures consisting o f the type 2 variety. Maimen and Larson's study [8] o f 51 adult patients noted no type 1 fractures, two (4%) type 3 fractures, and 49 (96%) type 2 fractures. Type 1 fractures are considered the least severe o f the odontoid fractures. The apical and alar ligaments, which normally secure the tip of the dens to the occiput, act to hold any avulsed fragments o f bone in proper orientation to allow for efficient healing. These fractures are stable, without risk o f atlantoaxial subluxation, and
i~~ ~i
B
Figure 2. (A) A computed tomography scan with sagittal reconstruction confirms the fractured odontoidprocess is anteriorly angulated. (B) A computed tomography scan shows the rounded baseof the dens with thefractured distal portion lying just anterior.
heal well in about 6 weeks with simple immobilization [10]. Type 3 fractures are more extensive than type 1 fractures, but because of the large cancellous surface o f bone exposed by the injury, they too are relatively stable and without risk of atlantoaxial subluxation. Nonunion is seen in about 8 % of those patients treated with traction (to allow for realignment) followed by immobilization. Wiring and fusion are performed only if union of the fracture does not occur. Seven weeks was the average healing time noted by Ryan and Taylor [ 10].
Odontoid Fracture
Surg Neurol 1985;24:529-32
531
Figure 3. A lateral midline tomogram through the cervical spine shows the fractured odontoid process angulated about 40 °.
T y p e 2 fractures are considered to be the most severe o f the odontoid fractures. Fractures o f this type are unstable and carry a high risk o f atlantoaxial subluxation with subsequent injury to the spinal cord or even death. Despite the severity of this injury, pediatric patients who present without neurologic deficit tend to do very well after reduction and immobilization with either a halo cast or minerva jacket. Sherk et al [13] experienced a 100% rate o f healing without growth disturbances or subsequent neurologic symptoms in 12 pediatric patients under the age of 6 years treated in this fashion. This is possibly due to the fact that this injury is similar to a separation o f the epiphyseal plate (Salter type 1 fracture) which tends to heal well in other locations. The adult population does not fare as well with this type of injury. Anderson and D'Alonzo [2] noted a 3 6 % rate of nonunion in conservatively treated adults with type 2 fractures. Ryan and Taylor's group of nine conservatively treated adult patients had a nonunion rate of 2 2 % after an average of 8 weeks of immobilization using either a halo cast or minerva jacket [10]. Wiring and fusion are considered the treatment of choice in both the adult and pediatric age groups should nonunion of the fracture occur after a trial o f conservative therapy.
Figure 4. Tomogram after placement of a brace shows near-complete anatomh alignment of the odontoid process.
Os o d o n t o i d e u m is an anomaly of the axis in which the dens is separated transversely from the base of C2. T h e distal portion appears as a small rounded ossicle separate from the base of C-2 and attached to the atlas by the transverse ligament [7]. This condition, originally thought to be congenital in origin, results in an anatomical arrangement similar to the type 2 odontoid fracture. T h e ossicle, which has no connection to the axis, results in a joint with inherent atlantoaxial instability. This joint is capable of subluxation with even minor trauma to the neck or occiput. "Acquired" os o d o n t o i d e u m following cervical trauma has also been recorded [6,7,14]. In these cases, a normal odontoid process was documented after initial injury to the cervical spine. Years later, after the spontaneous d e v e l o p m e n t of neurological symptoms, these patients demonstrated a free, rounded ossicle posterior to the anterior arch of C- 1 indistinguishable from
532
Surg N e u r o l 1985;24:529-32
a "congenital" os odontoideum. In these cases, it is thought that the initial injury resulted in an unrecognized fracture through the cartilaginous plate between the distal portion of the dens and the body of C-2. Subsequent resorption of this plate, possibly secondary to a compromised blood supply, and remodeling of the dens resulted in an os odontoideum indistinguishable on followup radiographs from the "congenital" variety. Undisplaced fractures of the odontoid process may be difficult to detect on a plain x-ray film of the cervical spine. Frequently, a true lateral view is difficult to obtain, and subtle angulation of the odontoid may be missed. In cases where the patient presents with persistent neck pain and neurological symptoms, or both, a lateral midline tomogram of the upper cervical spine should be considered, inasmuch as this offers the greatest reliability in demonstrating fractures of the odontoid process.
The authors wish to express their special thanks to Ms. Rhonda Kaye Tuttle for her time and effort in the preparation of this manuscript.
References 1. Amyes EW, Anderson FM. Fractures of the odontoid process: report of sixty-three cases. Arch Surg 1956;72:377-93.
Savader et al
2. Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg 1974;56-A: 1663-74. 3. Bohler J. Fractures of the odontoid process. J Trauma 1965; 5:386-91. 4. Crooks F, Birkett AN. Fractures and dislocations of the cervical spine. Br J Surg 1944;31:252-65. 5. Dyck P. Os odontoideum in children: neurological manifestations and surgical management. J Neurosurg 1978;2:93-9. 6. Fielding WJ, Griffin PP. Os odontoideum: an acquired lesion. J Bone Joint Surg 1974;56-A:187-90. 7. Hawkins RJ, FieldingJW, Thompson WJ. Os odontoideum: congenital or acquired. J Bone Joint Surg 1976;58-A:4 l 3-4. 8. Maimen DJ, Larson SJ. Management of odontoid fractures. J Neurosurg 1982; 11:471-6. 9. Nachemson A. Fracture of the odontoid process of the axis: a clinical study based on 26 cases. Acta Orthop Scand 1959;29:185-217. 10. Ryan MD, Taylor TFK. Odontoid fractures: a rational approach to treatment. J Bone Joint Surg 1982;64-B:416-21. l 1. Seimon LP. Fractures of the odontoid process in young children. J Bone Joint Surg 1977;59-A:943-7. 12. Sherk HH. Fractures of the atlas and odontoid process. Orthop Clin N Am 1978;9:973-9. 13. Sherk HH, NicholsonJT, Chung YMK. Fractures of the odontoid process in young children. J Bone Joint Surg 1978;60-A:921-4. 14. Stillwell WT, Fielding WJ. Acquired os odontoideum; a case report. Clin Orthop Relat Res 1978;135:71-3.