Re: Pars defect from rear MVC?

December 22, 2004

Jamey,

I don't know of any cases like this, although the lap seat

belt has been implcated in lumbar fractures before. It seems highly unlikly

to me that a rear-end collision would cause such a fracture, but never say

never I suppose. Questions I would want to know are:

What type of restraint system did the vehicle have?

What types of vehicles were involved?

What kind of speed are we talking? LOSRIC (low speed rear impact

collision) or was the patient hit by a semi doing 30 MPH?

What was the occupant's position at the time of impact (looking straight

ahead, or bent over changing the CD in the CD player?)?

What is the patient's occupation?

What level is the pars at?

Any previous low back pain (why were films taken 7 years ago?) It's easy

to miss a pars on just AP and LAT films. Were obliques taken 7 years ago?

Questions like this might help you reach your conclusion. But I defer

to our expert " Crash " Freeman...

Matt Terreri, DC

Pars defect from rear MVC?

>

> Has anyone had a case where a rear-end collision caused a bilateral

> pars defect? Just wondering because I have a case where x-rays

> seven years (not taken by me) were inconclusive for pars defect and

> x-rays after MVC in April (taken by me) show a bilateral pars

> defect. The patient claims no significant injuries in the past

> seven years. I do not think the mechanism of injury is possible in

> a rear-end accident, but I would like the opinions of my fellow

> colleagues, especially Freeman.

> Thanks,

> Jamey Dyson, D.C.

> Salem

>

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December 22, 2004

Hi Jamey and Matt,

Interesting and controversial question that you pose; here's a different one for you - can a rear impact collision cause a previously asymptomatic spondy to become symptomatic? In the population with asymptomatic pars defect, does the PD act as a diathesis for initial injury as well as prolonged recovery following trauma, relative to the population without PD?

First the biomechanics; is a pars defect loaded in a rear impact collision. The answer is most likely yes for most seats. As the seat back strikes the occupant, even at 5 mph (for a 5 mph speed change or delta V crash) the pelvis is the first part of the torso to be accelerated forward. The inertia of the torso above the pelvis results in a retro shear at the lumbosacral junction and the posterior elements sustain the greatest load. So there is the potential for spondy injury in a rear impact as it is a part of the body that sustains load.

There is no known threshold for how much force is required to cause a pars defect to develop traumatically, particularly if there is a predeliction to the condition, and there is even less known about how much force is required to cause a previously asymptomatic spondy to become symptomatic. If the films definitely show that the problem was not present prior to the crash and the new films definitely show that it is present after the crash and the symptom pattern matches up with the trauma then you have a traumatic pars defect on your hands. If you can't say for certain about the prior films then you most likely have a previously asymptomatic condition that was made symptomatic by the trauma.

Does this help?

Re: Pars defect from rear MVC? Jamey, I don't know of any cases like this, although the lap seat belt has been implcated in lumbar fractures before. It seems highly unlikly to me that a rear-end collision would cause such a fracture, but never say never I suppose. Questions I would want to know are: What type of restraint system did the vehicle have? What types of vehicles were involved? What kind of speed are we talking? LOSRIC (low speed rear impact collision) or was the patient hit by a semi doing 30 MPH? What was the occupant's position at the time of impact (looking straight ahead, or bent over changing the CD in the CD player?)? What is the patient's occupation? What level is the pars at? Any previous low back pain (why were films taken 7 years ago?) It's easy to miss a pars on just AP and LAT films. Were obliques taken 7 years ago? Questions like this might help you reach your conclusion. But I defer to our expert "Crash" Freeman... Matt Terreri, DC Pars defect from rear MVC?>>> Has anyone had a case where a rear-end collision caused a bilateral> pars defect? Just wondering because I have a case where x-rays> seven years (not taken by me) were inconclusive for pars defect and> x-rays after MVC in April (taken by me) show a bilateral pars> defect. The patient claims no significant injuries in the past> seven years. I do not think the mechanism of injury is possible in> a rear-end accident, but I would like the opinions of my fellow> colleagues, especially Freeman.> Thanks,> Jamey Dyson, D.C.> Salem>>>>>>> OregonDCs rules:> 1. Keep correspondence professional; the purpose of the listserve is to > foster communication and collegiality. No personal attacks on listserve > members will be tolerated.> 2. Always sign your e-mails with your first and last name.> 3. The listserve is not secure; your e-mail could end up anywhere. > However, it is against the rules of the listserve to copy, print, forward, > or otherwise distribute correspondence written by another member without > his or her consent, unless all personal identifiers have been removed.>

December 22, 2004

Would the shear forces would be increased if the seat belt is worn higher therby acting as a fulcrum against the lumbar spine vs. wearing it down low (like it's supposed to be) anchoring the pelvis?

One way to investigate the pars (maybe) would be a bone scan. Wouldn't that show if the lesion was currently active. Or is this too small of an area? If it was a new pars I'd think you would see some activity. On the other hand, if it is old I'm not too sure. ?

Matt

Pars defect from rear MVC?>>> Has anyone had a case where a rear-end collision caused a bilateral> pars defect? Just wondering because I have a case where x-rays> seven years (not taken by me) were inconclusive for pars defect and> x-rays after MVC in April (taken by me) show a bilateral pars> defect. The patient claims no significant injuries in the past> seven years. I do not think the mechanism of injury is possible in> a rear-end accident, but I would like the opinions of my fellow> colleagues, especially Freeman.> Thanks,> Jamey Dyson, D.C.> Salem>>>>>>> OregonDCs rules:> 1. Keep correspondence professional; the purpose of the listserve is to > foster communication and collegiality. No personal attacks on listserve > members will be tolerated.> 2. Always sign your e-mails with your first and last name.> 3. The listserve is not secure; your e-mail could end up anywhere. > However, it is against the rules of the listserve to copy, print, forward, > or otherwise distribute correspondence written by another member without > his or her consent, unless all personal identifiers have been removed.>