Evidence-Based Analysis of Odontoid Fracture Management
Evidence-Based Analysis of Odontoid Fracture Management
Object. The management of odontoid fractures remains controversial. Evidence-based methodology was used to review the published data on odontoid fracture management to determine the state of the current practices reported in the literature.
Methods. The Medline literature (1966-1999) was searched using the keywords "odontoid," "odontoid fracture," and "cervical fracture" and graded using a four-tiered system. Those articles meeting selection criteria were divided in an attempt to formulate practice guidelines and standards or options for each fracture type. Evidentiary tables were constructed by treatment type. Ninety-five articles were reviewed. Five articles for Type I, 16 for Type II, and 14 for Type III odontoid fractures met selection criteria. All studies reviewed contained Class III data (American Medical Association data classification).
Conclusions. There is insufficient evidence to establish a standard or guideline for odontoid fracture management. Given the extent of Class III evidence and outcomes reported on Type I and Type III fractures, a well-designed case-controlled study would appear to provide sufficient evidence to establish a practice guideline, suggesting that cervical immobilization for 6 to 8 weeks is appropriate management. In cases of Type II fracture, analysis of the Class III evidence suggests that both operative and nonoperative management remain treatment options. A randomized trial or serial case-controlled studies will be required to establish either a guideline or treatment standard for this fracture type.
The incidence of traumatic spinal cord injury in the United States is greater than 11,000 cases annually. More than 60% of spinal injuries affect the cervical spine, and approximately one out of five cases of all cervical spine injuries involve the axis. The most common axis injury is odontoid fracture, of which the majority are Type II or dens fractures. They occur at the junction between the odontoid process and the body of C-2, resulting in potentially disastrous instability. The biomechanical design of the C1-2 complex allows for more motion than any other single level in the cervical spine. This motion is primarily rotational, accounting for half of the axial rotation of the neck. Translational motion is restricted by the strong transverse ligament containing the odontoid process in the anterior portion of the ring of C-1. All other supporting ligaments are substantially weaker than those in the subaxial spine, facilitating the motion that occurs at this joint.
When the odontoid is fractured, there is no longer significant restriction of translational movements. Anterolisthesis or posterolisthesis, of the C-1 odontoid complex may occur relative to the body of C-2. If a significant degree of movement occurs, the function and integrity of the spinal cord may be jeopardized, possibly resulting in significant neurological deficit. As such, this is one of the most common sites of disruption in fatal cervical spine injuries.
The nonoperative treatment modalities for cases in which this type of fracture occurs are either no treatment or immobilization with a cervical fixation device, which includes a cervical collar or halo vest or Minerva jacket immobilization. Patients may also undergo a posterior fusion or anterior fixation procedure in which screws are placed.
A number of practice guidelines have been developed, using a scientific model, that have resulted in not only improved patient care but also a reduction in medical cost and time. The American Medical Association has suggested that a number of attributes are required for the development of scientifically sound, clinically relevant guidelines. The most important of these attributes focuses on the methods by which the literature is reviewed and the evidence graded. Data may be classified into four categories: 1) Class I evidence includes data collected in prospective trials, and these trials may or may not be randomized. 2) Class II evidence consists of data that are collected prospectively or retrospectively by using reliable data; Class II studies include cohort studies, prevalence studies, and case-controlled studies. 3) Class III evidence is based on retrospectively collected data; articles that fall into this category would include clinical series, database reviews, and case reviews. 4) Class IV evidence consists of case reports, anecdotal reports, testimony, theory, and common sense.
Treatment recommendations for any given disease entity may be weighted according to the available evidence. Treatment recommendations are generally divided into three groups. Standards reflect a high degree of clinical certainty, and these are based on Class I data or very strong Class II data. Guidelines reflect a moderate degree of clinical certainty in terms of therapeutic efficacy, and they are usually based on Class II evidence or a preponderance of Class III evidence. Treatment options reflect mild or unclear clinical certainty, and these are usually based on Class III data.
Outcome measures used to determine the success of treatment of odontoid fractures include bone fusion, morbidity, mortality, length and degree of disability cost, and length of hospitalization. For the purpose of this review bone fusion was the only criterion chosen. As such, it is widely recognized that radiographic determination of fusion is difficult to determine and may not coincide with other long-term outcomes such as pain, disability, neurological deficit, and function.
Object. The management of odontoid fractures remains controversial. Evidence-based methodology was used to review the published data on odontoid fracture management to determine the state of the current practices reported in the literature.
Methods. The Medline literature (1966-1999) was searched using the keywords "odontoid," "odontoid fracture," and "cervical fracture" and graded using a four-tiered system. Those articles meeting selection criteria were divided in an attempt to formulate practice guidelines and standards or options for each fracture type. Evidentiary tables were constructed by treatment type. Ninety-five articles were reviewed. Five articles for Type I, 16 for Type II, and 14 for Type III odontoid fractures met selection criteria. All studies reviewed contained Class III data (American Medical Association data classification).
Conclusions. There is insufficient evidence to establish a standard or guideline for odontoid fracture management. Given the extent of Class III evidence and outcomes reported on Type I and Type III fractures, a well-designed case-controlled study would appear to provide sufficient evidence to establish a practice guideline, suggesting that cervical immobilization for 6 to 8 weeks is appropriate management. In cases of Type II fracture, analysis of the Class III evidence suggests that both operative and nonoperative management remain treatment options. A randomized trial or serial case-controlled studies will be required to establish either a guideline or treatment standard for this fracture type.
The incidence of traumatic spinal cord injury in the United States is greater than 11,000 cases annually. More than 60% of spinal injuries affect the cervical spine, and approximately one out of five cases of all cervical spine injuries involve the axis. The most common axis injury is odontoid fracture, of which the majority are Type II or dens fractures. They occur at the junction between the odontoid process and the body of C-2, resulting in potentially disastrous instability. The biomechanical design of the C1-2 complex allows for more motion than any other single level in the cervical spine. This motion is primarily rotational, accounting for half of the axial rotation of the neck. Translational motion is restricted by the strong transverse ligament containing the odontoid process in the anterior portion of the ring of C-1. All other supporting ligaments are substantially weaker than those in the subaxial spine, facilitating the motion that occurs at this joint.
When the odontoid is fractured, there is no longer significant restriction of translational movements. Anterolisthesis or posterolisthesis, of the C-1 odontoid complex may occur relative to the body of C-2. If a significant degree of movement occurs, the function and integrity of the spinal cord may be jeopardized, possibly resulting in significant neurological deficit. As such, this is one of the most common sites of disruption in fatal cervical spine injuries.
The nonoperative treatment modalities for cases in which this type of fracture occurs are either no treatment or immobilization with a cervical fixation device, which includes a cervical collar or halo vest or Minerva jacket immobilization. Patients may also undergo a posterior fusion or anterior fixation procedure in which screws are placed.
A number of practice guidelines have been developed, using a scientific model, that have resulted in not only improved patient care but also a reduction in medical cost and time. The American Medical Association has suggested that a number of attributes are required for the development of scientifically sound, clinically relevant guidelines. The most important of these attributes focuses on the methods by which the literature is reviewed and the evidence graded. Data may be classified into four categories: 1) Class I evidence includes data collected in prospective trials, and these trials may or may not be randomized. 2) Class II evidence consists of data that are collected prospectively or retrospectively by using reliable data; Class II studies include cohort studies, prevalence studies, and case-controlled studies. 3) Class III evidence is based on retrospectively collected data; articles that fall into this category would include clinical series, database reviews, and case reviews. 4) Class IV evidence consists of case reports, anecdotal reports, testimony, theory, and common sense.
Treatment recommendations for any given disease entity may be weighted according to the available evidence. Treatment recommendations are generally divided into three groups. Standards reflect a high degree of clinical certainty, and these are based on Class I data or very strong Class II data. Guidelines reflect a moderate degree of clinical certainty in terms of therapeutic efficacy, and they are usually based on Class II evidence or a preponderance of Class III evidence. Treatment options reflect mild or unclear clinical certainty, and these are usually based on Class III data.
Outcome measures used to determine the success of treatment of odontoid fractures include bone fusion, morbidity, mortality, length and degree of disability cost, and length of hospitalization. For the purpose of this review bone fusion was the only criterion chosen. As such, it is widely recognized that radiographic determination of fusion is difficult to determine and may not coincide with other long-term outcomes such as pain, disability, neurological deficit, and function.
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