Classification of Lower Cervical Spine Injuries
It is not uncommon for cervical spine injuries to occur, with up to 3% of all trauma patients experiencing such injuries. Neurologic deficits, ranging from radiculopathy to incomplete or complete spinal cord injuries, are frequently linked with these types of injuries.
Prior to the development of spinal instrumentation, cervical spine injuries were commonly managed using traction and external bracing, typically without decompressing the neural elements.
The progress made in fixation techniques and our comprehension of the pathophysiological foundation of spinal cord injury has prompted surgeons to adopt a surgical approach when managing these injuries.
The surgical goal is to decompress the neural elements and maintain spinal stability to ensure long-term functionality. The level of instability that the injury causes to the spine can help determine the prognosis and possible treatment alternatives.
The objectives of a classification system are diverse and serve multiple purposes. The system ought to have a descriptive nature that permits effective communication, allow for differentiation of injury severity levels, offer valuable information for forecasting the clinical situation, and facilitate decision-making regarding treatment.
There is no solitary classification scheme for cervical spine injuries that has received widespread acceptance. There is a belief that none of the current systems meet all the expected criteria.
With the aid of modern imaging techniques, we are increasingly capable of identifying cervical spinal injuries. Despite the progress made in identifying such injuries, there is still a lack of a widely accepted and consistent classification system for subaxial cervical injuries.
Despite a lengthy history and various attempts, no classification systems for subaxial cervical spine injuries have been universally recognized or clinically validated. In some instances, a combination of these factors is employed.
Mechanism-based classification systems strive to anticipate the primary direction of injury based on the patterns observed in radiographs or computed tomography scans. These injury directions can be reproduced in cadaveric models, which can validate the predictions and aid in injury prevention research.
Several of the mechanisms used to describe injury mechanisms have become part of the accepted terminology used to describe injuries. In certain cases, mechanistic terminology implies a particular morphological pattern, such as compression fracture or flexion-distraction injury.
Regrettably, mechanistic systems may not always precisely portray injury patterns or the actual injury mechanism. Cadaveric studies have demonstrated that the implementation of the same injury direction can lead to distinct fracture patterns.
Fractures resulting from equivalent forces and direction encompassed vertebral body bursting fractures and bilateral facet dislocations. Mechanism-based systems also have limitations, such as a lack of understanding of the head position during impact, the impact of musculature, and how disease states like age, ankylosis, and osteoporosis can affect injury patterns.
Additionally, it has been demonstrated that under acute loads, the spine can buckle, leading to varying injury vectors at distinct levels. To illustrate, at one level, there might be a flexion moment, while at a lower level, an extension moment with rotation may occur.
After the spine becomes unstable, it can assume a nearly infinite range of positions, posing a challenge to identifying the precise mechanism. Secondary vectors that act on the injured spine are not taken into consideration by mechanistic classification systems.
Injury patterns observed on radiographs, CT, and occasionally MRI are described using morphologic classification systems. However, although morphological terms may indicate the mechanism of injury, they do not always provide a characterization of instability.
Morphologic terms often describe the mechanism of injury, but they may not always accurately depict the degree of instability. Certain morphological descriptors are considered as a pathoanatomic entity despite implying a mechanism. Using purely morphologic classification systems makes it challenging to avoid the use of mechanistic terms.
An effective classification system should have clinical relevance, ease of use, applicability in different scenarios, teachability, reliability, and validity. It should also be easily applicable in various settings, especially during the initial patient evaluation, and assist in determining the appropriate treatment approach.
The system of morphologic descriptions that is being suggested is founded on patterns that are widely used and recognized, and it does not include numerous subgroups such as the Allen-Ferguson or the AO system, as the distinctive patterns that differentiate injuries with similar patterns can be provided by the quantification scale.
A medical classification system must possess both reliability and validity. Reliability is the consistency of the system across different measurements and observers, and is often measured using statistical values such as ICC or kappa. Validity refers to the accuracy of the system in assessing the condition.
The Cervical Spine Injury Severity Score has been found to have excellent reliability, with intraobserver ICC >0.97 and interobserver ICC >0.88, and the results are consistent regardless of observer experience.
Naming or describing an injury is important for communication and distinguishing it from others, but it may not provide information on prognosis, treatment, or severity. To overcome these limitations, quantifying the severity of instability can be helpful, incorporating both bony and ligamentous changes and providing numerical values for analysis and treatment decisions.
The injury severity score system has demonstrated reliability in assessing stability in subaxial cervical spinal injuries, which can help in developing treatment algorithms for clinical trials.
I am Vedant Vaksha, Fellowship trained Spine, Sports and Arthroscopic Surgeon at Complete Orthopedics. I take care of patients with ailments of the neck, back, shoulder, knee, elbow and ankle. I personally approve this content and have written most of it myself.
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