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Jeffrey Cronk, DC JDFeb 29, 2024 4:20:33 PM5 min read

Decoding AOMSI: Insights into Spinal Health and Communication


In the context of spinal health, the concept of Alteration of Motion Segment Integrity (AOMSI) emerges as a pivotal yet frequently misconceived element. It is imperative to underscore that AOMSI does not constitute a diagnosis per se but delineates a specific pathological condition associated with the spine, as delineated in the American Medical Association (AMA) Guides to the Evaluation of Permanent Impairment. According to these guides, an impairment is characterized as a "Loss, loss of use of, or a derangement to a body part..." Specifically, AOMSI pertains to a derangement of the spinal support ligaments, a condition that precipitates excessive spinal motion and instability, thereby constituting an alteration in the integrity of the motion segment.

This condition is recognized as a grave injury within the medical community. The AMA Guides articulate that, in instances where routine radiographic evaluations yield normal results and there is an absence of severe trauma, the occurrence of motion segment alteration is considered exceptional. Furthermore, these guidelines assert that the motion of individual spinal segments cannot be ascertained through physical examination alone but requires the utilization of flexion-extension X-ray for definitive determination. This assertion underscores the necessity of precise stress radiology testing for the accurate diagnosis of AOMSI, as physical examination procedures alone are insufficient. Consequently, no medical practitioner can reliably identify this injury without recourse to radiographic studies, as it remains undetectable via other imaging modalities.

Defining AOMSI: Measurements and Clinical Implications

Specific metrics quantitatively determine AOMSI: it is defined by either an excess of 3.5 millimeters in translational movement or an angular deviation exceeding 11 degrees between adjacent spinal segments. Additionally, certain standards consider a displacement exceeding 20% of one vertebral body over another as indicative of AOMSI, with precise criteria also established for the lumbar spine. It is essential to clarify, however, that AOMSI does not represent a diagnosis in itself; rather, it denotes a degree of excessive spinal motion that leads to the assignment of a permanent impairment rating within the framework of the American Medical Association (AMA) Guides to the Evaluation of Permanent Impairment.

These guides serve a critical function in standardizing the classification of injuries, facilitating consensus among medical professionals regarding the nature of such injuries and their impact on an individual's daily living activities—termed a whole body impairment. For instance, a 10% impairment rating implies that the individual's capacity to perform daily activities, including sleeping, walking, running, self-care, and others, is somewhat compromised, either presently or prospectively.

As elucidated in the 5th Edition of the guides, the primary objective is to provide a systematic approach for rating impairments. This facilitates determinations by adjudicators and others regarding the appropriate financial compensation for individuals who have experienced a measurable physical or psychological loss due to injury or illness. This methodology represents the sole objective means to unify understanding and expedite the medico-legal process, a process that medical practitioners must navigate when treating patients with injuries.

Spinal Instability and Subluxation: The Real Concerns

The pathological state linked to Alteration of Motion Segment Integrity (AOMSI) is the impairment of the non-disc spinal support ligaments, leading to undue movement within the spinal motion unit, potentially giving rise to a condition known as spinal instability. Spinal instability is diagnosed when such persistently excessive movement adversely affects the nerves, manifesting as motor deficits, sensory disturbances, or pain.

In the realm of chiropractic medicine, practitioners have recognized and effectively addressed this condition under the nomenclature of spinal subluxation. According to chiropractic literature, AOMSI is thus integrated into the broader concept of the subluxation complex. This perspective aligns with the broader medical acknowledgment of spinal instability, highlighting the interdisciplinary recognition of the condition's significance and impact on patient health.

Ligament Laxity and Its Role

Ligament laxity, meaning the ligament is lax or loose, is a related term. However, it only describes the state of the ligament and does not necessarily imply a problematic condition. It's when this laxity leads to interference with nerve function, causing symptoms, that it becomes a concern, often termed spinal instability or spinal subluxation.

Common Misconceptions in Clinical Practice

A prevalent misconception within the domain of spinal injuries is the notion that for excessive spinal motion to be clinically significant, it must meet the criteria for Alteration of Motion Segment Integrity (AOMSI) as outlined in the AMA guides, classified as a Grade III spinal sprain. Although such a diagnosis indicates a severe level of impairment, it's critical to recognize that Grade II sprain injuries can also profoundly affect individuals, despite being associated with a lower impairment rating. The variability in individual responses to these injuries is substantial, influenced by a myriad of factors including general health status, lifestyle, the presence of dormant pre-existing conditions that may predispose one to greater vulnerability to injury, and the existence of active pre-existing conditions at the time of injury.

When addressing issues of Alteration of Motion Segment Integrity (AOMSI) and associated spinal injuries, particularly in the context of legal discussions, it is crucial to employ terminology and concepts that are accessible and clear to all parties involved. For example, current guidelines for spinal fusion surgery often cite AOMSI as a criterion for excessive spinal motion that must be met before insurers authorize coverage for the procedure. Thus, while a lawyer or insurance adjuster might not be familiar with the specific terminology of "AOMSI" as it pertains to the AMA Guides, they are likely to understand the implications of spinal fusion surgery. Therefore, it can be more effective to explain that AOMSI represents a degree of injury to the spinal support ligaments severe enough to necessitate spinal fusion surgery, as recognized and approved within numerous guidelines that govern insurance coverage for such surgical intervention.

The Key to Effective Communication: Starting with Common Ground

When engaging with legal professionals or even within the medical community, it's crucial to begin discussions on familiar ground. Utilizing well-understood concepts like surgical guidelines can be the bridge to a greater understanding of the significance of this condition.


While AOMSI and its related concepts are vital in understanding spinal health, the way they are communicated is equally important. Starting with relatable concepts and gradually building up to more complex ideas ensures effective communication, enhancing understanding and management of spinal health issues.