Lateral tilt APOM and ligament damage

Disclosure:

Medical Disclaimer: The content shared in this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you’ve heard on this podcast.

Legal Disclaimer: Similarly, the legal information provided is not a substitute for legal advice. Laws and regulations can vary widely by jurisdiction, and the application of the law depends on the specific circumstances of each situation. Please consult a licensed attorney for personalized legal advice pertaining to your case.

I have spent a lot of time with the podcast discussing ligament damage. This is a common injury I see in my practice with MVCs or other traumas.  Ligament damage is so common that I believe almost everyone in a MVC has ligament damage.  The extent of the ligament damage can vary a lot.  For forensic work it becomes important to show the ligament damage.  In some cases, there is no objective evidence of ligament damage, but I am certain that it occurred.  If a patient has no prior neck symptoms and was in a MVC and then has an onset of neck pain it is more likely than not that there is ligament damage.  Sometimes mechanism of injury is enough to show ligament damage.

It is always better in a legal case to have objective evidence of ligament damage on imaging.  I talked about catastrophic ligament damage or AOMSI on the first 3 podcasts as well as 19 and 21.  When it comes to AOMSI it is possible to show objective evidence of ligament damage.  I covered ways to show causation of this ligament damage in other podcasts as well. 

On the 13^th podcast I talked about sub catastrophic ligament damage.  That podcast showed objective evidence of ligament damage in the cervical spine that is not AOMSI.  I talked about MRIs and how they can show signs of ligament damage.  The AOMSI and sub catastrophic ligament damage studies cover changes in angular motion and translation of the spine in flexion and extension. 

Determining other ways to objectively show ligament damage is the topic of today’s study which is Diagnostic Accuracy of Videofluorosocopy  for symptomatic  Cervical Spine Injury Following Whiplash Trauma.  This was published in 2020 in the Internation Journal of Environmental Research and Public Health by Michael Freeman et al. 

This study come out around 30 years after some of the original research in AOMSI.  This study looked at a lot of different imaging findings to assess ligament damage.  They took 119 injured patients and 77 volunteer uninjured patients.  This study was done with videoflurosopy or motion x-rays.  This is different than a flexion and extension motion x-rays.  This is a constant x-ray that can be seen in video.  They included people ages 16-65.   The participants had to have an absent history of cervical fractures, congenital anomaly, inflammatory arthritis, diagnosed connective tissue disorder, metastatic disease of the spine, or any other bony or neurological abnormality that would affect the examination.  The patients in the uninjured group had to have no history of chronic neck pain or episodic neck pian last for over 1 week.  The injured patients had neck pain for over 6 weeks after a whiplash injury. 

For the imaging they took an AP view which is front to back.  They then took the AP view and had them laterally flex.  They then took the AP view and had them open their mouth and then laterally flex.  The open mouth is to get the teeth out of the way of the upper cervical spine.  The next view was a lateral or side view that included flexion and extension views.  The last view was an oblique angle with flexion and extension x-rays.

This study was looking for stability of the spine.  As seen with other studies instability will have translation or movement of 1 vertebra compared to the adjacent one.  They reported that they would use the rule of 2s for translation.  This rule of 2s comes from the text book Imaging of Vertebral Trauma 3^rd edition by Daffner.  The rule of 2s is that the normal spine will not have translation of over 2mm.  As with other studies they also assessed change in angular motion between adjacent levels.  They used 10 degrees as the upper threshold of normal for changes in angular motion based on the AMA Guides showing 11 degrees as the start for AOMSI.  This number was based on the 1970’s White study. 

This study looked at 9 different findings that could suggest ligament damage. 

-The first is lateral overhang of C1-2 showing 2mm or more.   This is seen with lateral flexion.

-The second assessed the peri-odontoid space symmetry.  This is the gap between the dens and the lateral masses of C1.  This was seen in ApOM. 

-The 3^rd was translation of over 2mm seen with flexion and extension lateral views. 

-The 4^th was Changes in angular motion over 10 degrees from the lateral views. 

-The 5^th was Spinous process engagement on the lateral view.  The spinous process should increase distance with flexion.  They looked at the degree of synchronous movement between adjacent spinous processes. 

-The 6^th was spinous process coupled movement.  When the healthy spine laterally flexes to the left the spinous process should rotate to the right.  They assessed if the spinous process rotated to the opposite side of lateral flexion. 

-The 7^th was facet gapping on the AP view with lateral flexion.  The facet joints should have no gapping at maximum lateral flexion. 

-The 8^th was facet gapping on the oblique lateral flexion views.  There should be no facet joint gapping at maximum lateral flexion.

-The 9^th was facet symmetry on the oblique view.  The movement and degree of gapping should be symmetrical between sides. 

Of these 9 measurements some of them are done at every level.  This makes for more than 9 positive findings possible.  For example, translation and change in angular motion can be seen at multiple levels.  Of these 9 measurements the uninjured volunteers had an average of 1.2 positive findings.  The injured population had an average of 7.0 positive findings.    Of interest none of the volunteer uninjured population had 0 positive findings.  This study showed that the odds of having an injured spine went up by 2.6 for each additional abnormal finding.  This study showed that it is uncommon for uninjured patients to have over 1.2 positive findings.  With each additional positive finding it is more likely that the patient has cervical ligament damage. 

Can this study be applicable to a normal x-ray machine and not videofluroscopy?  These 9 measurements are done at end range or maximum movement.  This can be done with standard x-rays.  The movement seen with a video instead of end range x-rays can add a lot to the assessment, but I believe if the static x-rays are taken currently, we can get the measurements needed. 

This study goes a lot further into objective measurement of ligament injury than the AOMSI or sub catastrophic ligament damage studies.  The more positive findings seen the more likely that patients have ligament damage, but we would be unable from this study assess catastrophic complete failure of ligaments (unless they correlate with the AOMSI study).    

This study is fascinating to me.  What a great way to assess for ligament damage in the cervical spine.

To sum up this study they were able to show objective demonstrable signs of ligament damage on motion x-rays.  Instead of just the later flexion and extension views they added lateral flexion with the mouth open to assess more ligament damage.  They have 9 measurements of which some are seen at every level and bilaterally.   This allows for multiple positive findings.  The healthy population on average had 1.2 positive findings.  The odds of a patient having ligament damage went up by 2.6 times for each additional abnormal findings.  This is a tool used to increase objectifying ligament damage in the cervical spine.

Real world

For today’s real world example I would like to cover impairment rating for ligament damage.  In the AMA Guides to the Evaluation of Permanent Impairments 6^th edition.  The impairment rating guides offer a quantitative assessment of how serious an injury is.  The guides give a number of what is called whole body impairment rating.  I like to compare it to what percentage of the patient’s body was lost in their injury. 

The 6^th edition offers 2 categories for spinal ligament damage.  The first is quote “Non-specific chronic, or chronic recurrent neck pain also know as chronic sprain/strain, symptomatic degenerative disc disease, facet joint pain, chronic whiplash, etc.” end quote.  For this impairment there has to be a documented history of injury.  There also has to be symptoms with objective findings.  If this criteria is met the patient will qualify for a 1-3% whole person impairment rating. 

The second category for spinal ligament damage in the guides is for AOMSI or Alteration of Motion Segment Integrity.  For the AOMSI impairment rating we have to have x-rays showing AOMSI.  With AOMSI findings the patient can qualify for a 4-30% whole person impairment rating.  This allows for a high level of impairment. 

 If I had the opportunity to write a new edition of the AMA Guides I would use today’s study for impairment ratings for spinal ligament damage.  I don’t think they are calling me anytime, but I think this would be a more accurate way to assess ligament damage.   I would increase the impairment rating for each of the positive findings from today’s study seen on the x-rays.                          

The addition of today’s study gives a lot more opportunities to assess ligament damage in the cervical spine objectively.  This type of evaluation should be done with patients who fail to make progress to assess for hard to find objective evidence of ligament damage.  Remember ligament damage is always permanent and significant.  For a refresher on what ligament damage is like listen to podcast 1, 3, 15 and 16.

Thanks for listening to todays podcast.  Please subscribe so you don’t miss out on any medical legal research.