Sunday, August 23, 2009

Identification of vertebral fractures

 

    
        
                                                                                         

 

 Placebo effect has been know from time of Plato cited by Socrates about the cure of headache “ was a kind of leaf, which required to be accompanied by a charm, and if a person would repeat the charm at the same time that he used the cure, he would be made whole; but that without the charm leaf would be of no avail.” However a therapy to be true placebo, ethically speaking, must be safe to use, without any adverse effects and possible less invasive we can. That’s a problem of some “minimally invasive” techniques that in the developed countries during the last decade are increasing exponentially. Future of surgeons would be “endoscopically and fluoroscopically” followed tecniques, allowing shorter hospitalization times, prompt delivery and fast recovery of patients. Radiologists, if not involved into Nuclear Medicine, are better called Interventional Radiologists, a way to identify a Medical Doctor directly involved into the therapeutic measures adopted for increasingly diseases. The old radiologists, reading and comparing X-ray exams, are disappearing and substituted by Neuroradiologist. The problems is a correct use and approach to new available tecniques, too fast approaching on the free market without the due time required to completely understand their potential utility-damage ratio.

A clear example of a wrong use of these tecniques is clearly demonstrated by two article published on The Journal on the isssue of August 6, 2009 concerning vertebroplasty use in osteoporotic patients. If we don’t know the pathophysiology of osteoporotic verbral fractures, but also only what is osteoporosis, clearly we could be charmed and easly attracted by these technologically revolutionary tecniques.

Under fluoroscopic guidance, the neuroradiologist first infiltrated the skin underlying pedicles of fracture site with a 25 Gauge needle with 1 % lidocaine reacing the subcutaneous tissue. Sorthly after, using a 23 Gauge needle with 0.25% of bupivacaine infiltrated the periostium of the posterior verterbral lamina. At this point aan incision is made on the skin, and a 11-13 Gauge needle is placed postero-laterally relative to the eye of vertebral pedicle. Gently the operator mouves the needle through the pedicle into the anterior two third of the fractured vertebral body following the needle progression with fluoroscopic images antero-posteriorly and laterally. Barium opacified Polymethylmetacrylate (PMMA) is now infused under fluoroscopic lateral control. A Unipedicular approach can be used infusing a total of approximately 3 ml of PMMA injected directly into a single side. However a Bipedicular approach can be used if there is inadequate instillation of cement into vertebral body. The PMMA is stopped when a substantial resistance is met or when the PMMA reached the posterior quarter of vertebral body or if the PMMA leaked into extraosseous structures or veins. After the vertebroplasty the patients are followed in the supine position for 1 to 2 hours before discarge administering intravenously immediately after PMMA injection a cephalotin antibiotic treatment.

In the two studies cited above the Authors demonstrated quite inequivocably that vertebroplasty is equal to placebo treatment in back pain relief particularly in short term. The anesthetic effect is probably important in explaining the shorter pain relief and easy manipulation by operators of vertebral bodies; however it cannot explaine the beneficial effect the Authors founded also after 4 or 6 weeks in most patients.

As the Editor outlines, President Barack Obama recently called for more comparative-effectiveness research in order to establish true safety and effectiveness of a given treatment compared to other one as part of American Recovery and Reinvestement Act (ARRA). People of developed countries probably pay the prize of great advances in technologies, so that in great medical challenges, such as acute pain of vertebral fracture, informed patient take also an less invasive choiche, as vertebroplasty, in order to have best and faster pain relief. However we have to pay attention to correctly inform the patients in order to obtain a true informed choiche, and the demonstration of equal affectiveness of placebo anestetic injection and PMMA vertebral reconstruction help us in doing that.

 

# 7 Back surgery emilaminectomy and laminectomy

Also the presence of intravertebral edema during MRI, used in the studies under discussion, is not universally accepted target of vertebral osteoporotic fracture. Such as CT scan, also MRI, are usually only required in the presence of localized pain, focal neurological signs, or symptoms suggesting cord compression, disc erniation, a radiculopathy, or the clinical suspicion of primary or metastatic lesions, but not in osteoporotic patients.

What is the correct approach to a vertebral fracture?

# 14 Bone DXA scan

 

The problem is besides all the definition of vertebral fracture, at present there’s no Consensus Giudelines on osteoporotic vertebral fracture definition. Identification of vertebral fracture can be very difficult, because the shape of normal vertebral bodies varies widely between individuals. Vertebral bodies can be present abnormal features because non-osteoporotic deformities and errors in radiological projection can induce a misdiagnosis of fractured body. We have to remember that about 50% of vertebral fractures are asymptomatic and therefore are only casually identified. They are not the source of pain !Even when chest radiographs or vertebral images are correctly obtained only 35 to 50% of all radiographic vertebral fractures are correctly reported. It has been estimated that only 19% of these fractures reach clinical attention and can be correctly treated with a antiosteoporotic treatment. In view of high radiation exposure routine chest and lumbar radiographs are not recommended, but the availability of vertebral imaging using DEXA take the advantage of utilize an image of near radiographic quality available with a low fraction of the radiation dose.

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Imaging vertebral fractures using DXA is called Vertebral Fracture Assessment (VFA).

The disadvantage of VFA is poor image resolution compared to conventional radiography, CT or MRI and the increased difficulties in imaging the thoracic spine, expecially above T7. Between 5 to 15% of thoracic vertebrae can be visualized only by conventioonal radiography.The sensitivity and specicificty of this approach compared with conventional radiography varies with the kind of approach used to definy a vertebral fracture:

- Morphometric

- Semiquantitative (SQ)

- Visual identification

One advantage of DXA imaging is that the scan are not subjected to the same degree of projection distortion as conventional radiography because the X-ray beam is always orthogonal to the spine. Reducing the X ray diffraction effect. Moreover DXA reduces the frequency that soft tissue obscure the endplates compared to single energy mode. Side-by-side viewing facilitates the identification of incidental vertebral fractures.

Morphometrical analysis

It uses the measurement of vertebral height to define vertebral fractures. A normative daatabase is established against which the vertebrae are compared, There are a number of different morphometric approaches that vary with the criteria by which they define a vertebral fracture and in the reference data used, The most widely used approaches to identify prevalent and incidental vertebral fractures are the two different algorithms proposed by McCloskey et al (3) and Eastell R et al (4). Morphometric analysis has a high sensitivity and moderate high specificity in discriminating between normal vertebrae and fractured vertebrae. Moreover, all the morphometric approaches for defining prevalent and incident vertebral fractures are correlated with clinical risk factors for vertebral fractures. A loss of vertebral height of 20 to 25 % is usually used to define an incident vertebral fracture; using this definition comparable ability to identify any vertebral frcture is present irrespective of aproach used to define a baseline fracture. As mentioned above VFA is more effective in identifying moderate to severe deformities with a sensitivity of 81.6% for grade 2 deformities, whereas mild grade 1 deformities identifiation has a sensitivity as low as 22%. Finally , the precision error is small if compared with the reduction in vertebral height of 20 to 25% threshold used to define vertebral fractures and it is less using conventional radiology than using VFA.

Semiquantitative analysis

SQ analysis combines measurements of vertebral height with subsequent evaluation of all vertebrae with a short vertebral height by an expert reader. This combined approach enables the identification of non-osteoporotic fracture vertebral deformities, which are not identified using morphometric analysis alone. As a consequence, SQ analysis is able to reduces false positive results.The most widely used SQ analysis is that of Genant HK (6). Baseline or prevalent vertebral fractures are graded from “0” equal to normal to “3” equal to severe fracture, and incident fractures are defined as an increase of more than or equal than 1 grade on follow-up radiographs.

Genant grade 1 corresponds to an 20 to 25% reduction in anterior, middle or posterior height

Genant grade 2 corresponds to a 25 to 40% reduction in any height

Genant grade 3 corresponds to more than 40% reduction in any vertebral height

Mild grade 1 SQ vertebral deformities are frequently not associated with low BMD values.The interobserver agreement for conventional radiographs or DXA images is similar with a K score of 0.53 and 0.51 respectively.This approach is currently those recommended by International Society of Clinical Densitometry for diagnosing vertebral fractures with VFA.

# 13 BMD Distribution and fracture rate

Algorithm Based Qualitative Approach

ABQ approach differs from SQ analysis because the last one is based only on variations of vertebral height; not considering variations on endplates cracks or breaks as the primary event with a subsequent evaluation of vertebral height. ABQ focus more attention on the vertebral endplate alterations rather than on short vertebral height. Using ABQ we have a greater association with low BMD and interobserver agreement for radiography and DXA images of 0.74 and 0.65 respectively. So that mild vertebral fractures identified with ABQ are more strngly associated with osteoporosis than when this mild fractures are identified with SQ method. The definition of vertebral fractures includes the presence of breaks in the cortex of vertebral body; these breaks always occurs in the center or either the superior or inferior endplates that are the weakest area of endplate because it is more distant from the strong outer vertebral ring. As a consequence, the endplate buckles or collapses under pressure because of interventebral disc and it results in a concave appearance to the superior and/or inferior endplate. If the concavity extend beyond the inner border of the vertebral ring , it is unlikely to represent an osteoporotic fracture. A vertebral fracture initially involves a crack of the superior or inferior endplate with or without the simultaneous loss of vertebral height. As severity of the fracture progresses, the vertebral ring fractures resulting in loss of height and buckling of the anterior, lateral and occasionally posterior cortex. It is important to outlined these aspects because there is considerable variation in vertebral shape resulting in osteoporotic and non osteoporotic deformities that can result in considerable intraobserver error even among expert readers.

Commonly we can see wedge deformity fracture associated with endplate fracture where is present a fracture of the anterior cortex of vertebral body.

A true compression fracture associated with endplate fracture is an osteoporotic compression fracture of superior endplate associated with fracture of anterior and posterior cortex of vertebral body.

Clinical recommendations for screening for vertebral fractures

The current recommendations for using fracture assessment through DXA imaging (VFA) by the International Society of Clinical Densitometry are:

  1. When the results may influence clinical management
  2. If BMD is indicated then consider performing VTA if clinically indicated in:

- Documented height loss greater than 2 cm

- Historical height loss greater than 4 cm since young adult

- History of fracture after 50 years old

- Commitment to long term oral or parental glucocorticoid therapy

- History or findings suggestive of vertebral fracture not     documented by previous radiographic imaging

Therefore, it is reasonable to screen all patients with osteopenia using VFA, if it will alter the management of the patient. In a study at Mayo Clinic 16% of patients 60 to 69 years old and 45% of those older than 70 years had a previously undiagnosed vertebral fracture on VFA.

References

Kallmes DF, Comstock BA, Heagerty PJ et al. A randomized trial of vertebroplasty for osteoporotic spinal fractures. N Engl J Med 2009;361:569-79.

Buchbinder R, Osborne RH, Ebeling PR et al. A randomized trial of vertebroplasty for painful osteoporotic vertebral fractures. N Engl J Med 2009;361;557-68.

Weinstein JN. Balancing science and informed choice in decision about vertebroplasty. N Engl J med 2009;361:619-21.

McCloskey EV, Spector TD, Eyres KS et al. The assessment of vertebral deformity: A method for use in population studies and clinical trials. Osteoporosis Int 1993;3:138-47.

Eastell R, Cedel SL, Wahner HW et al. Classification of vertebral fractures. J Bone Miner Res 1991;6:207-15.

Genant HK, Jergas M, Palermo L et al. Comparison of semiquantitative visual and quantitative morphometric assessment of prevalent and incident vertebral fractures in osteopororsis. The Study of Osteoporotic Fractures Research Group. J Bone Miner Res 1996;11:984-96.

Rea JA, Li J, Blake GM et al. Visual assessment of vertebral deformity by X-ray absorptiometry: A highly predictive method to exclude vertebral deformity. Osteoporosis Int 2000;11:660-8.

Siminoski K, Jiang G, Adachi JD et al. Accuracy of height loss during prospective monitoring for detection of incident vertebral fractures. Osteoporosis Int 2005;16:403-10.

Siminoski K, Warshawski RS, Jen H et al. The acuracy of historical height loss for the detection of vertebral fractures in postmenopausal women. Osteoporosis Int 2006;17:290-6.

Schousboe JT, Ensrud KE, Nyman JA et al. Cost-effectiveness of vertebral fracture assessment to detect prevalent vertebral deformity and select postmenopausal women with a femoral neck T-score lower than 2.5 SD for alendronate therapy: A modeling Study. J Clin Densitom 2006;9:133-43.

Who take care about that?

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