Osteoporotic = Vertebral Fractures

Vertebroplasty=20 in Osteoporotic Vertebral Fractures

Dr=20 Charanjit Singh Dhillon

M.S,=20 DNB (Orth), FNB Spine Surgery, D-Orth, FCPS,

Director=20 MIOT Center for Spine Surgery,

MIOT=20 Hospitals, Chennai.

Abstract

Osteoporosis=20 is a significant public health problem. Vertebral fractures are the most = common=20 fractures in patients with osteoporosis, along with proximal femoral and = wrist=20 fractures. These fractures may cause acute or chronic pain, reduce the = quality=20 of life, and shorten life expectancy. Several medications are available = that=20 reduce the risk of fracture. Vertebroplasty may reduce or relieve pain = in=20 carefully selected patients.

Introduction

Osteoporosis=20 is "a systemic skeletal disease characterized by low bone mass and=20 micro-architectural deterioration with a consequent increase in bone = fragility=20 with susceptibility to fracture." In simpler terms, it is a reduction in = the=20 quantity and quality of bone that leads to increased bone fragility and=20 fractures.

Osteoporosis=20 is a silent disease -- there are no symptoms or signs of low bone mass = or bone=20 loss. Typically, years or decades of bone loss are required before an = individual=20 becomes at high risk for bone fracture. Once the patient experiences a = fracture,=20 more fractures are likely to occur in the near future. =

Vertebral=20 compression=20 fractures are the most common fractures in = patients=20 with osteoporosis, after proximal femoral and wrist fractures. = They are=20 identified in nearly 25% of women aged above 50 years. The incidence = increases=20 by about 15% with each passing decade. These fractures are nearly twice = as=20 common in females as compared with males. For reasons not clearly = understood,=20 only one third of spinal compression fractures are painful; most of = these are=20 refractory to medical management.

A = number of=20 diseases and conditions predispose individuals to osteoporosis and = secondary=20 vertebral compression fracture. These include the following:=20

Advanced age =
Asthma=20
Cirrhosis=20
Diabetes = mellitus=20
Emphysema=20
Menopause=20
Oophorectomy,=20 bilateral
Renal = disease, chronic=20
Rheumatoid = arthritis=20
Transplants=20
Tumors,=20 parathyroid-related peptide
Vitamin D=20 deficiency

In = addition,=20 certain drugs are also associated with osteoporosis, as follows:=20

Anticonvulsants=20
Cytotoxic = drugs=20
Alcohol=20
Thyroid = replacement=20 drugs
Steroids=20
Heparin=20

(Source:=20 National Osteoporosis Foundation, 1998)

Patients with=20 compression fractures typically present with a sudden onset of intense = back=20 pain, often after a relatively benign activity. Many patients refer to=20 intractable pain after a sneeze or a cough. The pain tends to be = debilitating.=20 Patients find it difficult to find a comfortable position, and = therefore, they=20 have difficulty sleeping. Many patients refer to sleep in a seated or=20 semireclining position.

Though=20 majority of vertebral fractures eventually heal with conservative = management=20 some of them will fail to heal giving rise to chronic pain. This chronic = pain is=20 due to changes in spinal alignment, spasm of paraspinal muscles, and = stretch on=20 posterior spinal ligaments.

Multiple=20 compression fractures lead to kyphotic deformity ("dowager's hump"), = loss of=20 height, crowding of internal organs, inactivity-induced physical = deconditioning,=20 and changes in self-image leading to a significant impact on self esteem = and=20 activities of daily living. Biomechanically with each vertebral fracture = there=20 is forward shift of weight bearing axis, leading to increased load on = the=20 anterior column of weak osteoporotic vertebrae predisposing them to = further=20 fractures.

Relatively=20 new procedure, vertebroplasty have been introduced for the management of = unusually severe or persistent pain from vertebral fractures. It = involves=20 percutaneous injection of bone cement into one or more fractured = vertebra. Pain=20 relief has been reported in 60 to 100% of cases in which this procedure = was=20 performed.

VERTEBROPLASTY

History=20

In = 1984,=20 vertebroplasty was first successfully performed in France for the = treatment of a=20 cervical vertebral hemangioma (Deramond, 1998). Since then, the = application of=20 vertebroplasty have been expanded to include the treatment of the = intense pain=20 caused by vertebral compression fractures that is refractory to = conventional=20 therapies

Vertebroplasty=20 involves the injection of acrylic cement under local anesthesia and = either=20 fluoroscopic guidance or, less commonly, CT guidance into fractured = vertebra.=20 Typically, the techniques are performed as an outpatient procedure and = require=20 approximately 40 minutes per level treated. Pain reduction or = elimination is=20 immediate, and the risk of complication is low.

Vertebroplasty=20 is a treatment for pain. Theoretically, 2 mechanisms may account for the = pain=20 reduction associated with the injection of methylmethacrylate. The first = mechanism may be as a result of acrylic fusion of the fragments into a = single=20 block, preventing the painful motion of the individual fracture = fragments=20 against each other. The second mechanism of pain reduction may be = related to the=20 heat produced by the polymerization process as the acrylic hardens. An = added=20 benefit is that deposition of acrylic within the vertebra significantly=20 strengthens osteoporotic bone, reducing the likelihood of repeat = fracture.=20

PATIENT=20 SELECTION

A patient=20 with painful osteoporotic compression fracture which has failed to = respond to a=20 fair and adequate trial of conservative treatment is the ideal candidate = for=20 vertebroplasty. Impending vertebral fracture due to localized = osteoporosis=20 following non-septic lesion such as hemangioma, multiple myeloma may be=20 additional indications. = Vertebroplasty may also=20 be applied prophylactically to an at-risk vertebra between 2 other = abnormal=20 vertebrae.

Inclusion=20 criteria include the following:

=B7 =20 Fracture less = than 12=20 months old.

=B7 =20 Pain localized = to a=20 fracture or tumor,

=B7 =20 Pain = refractory to=20 medical management,

Exclusion=20 criteria include the following:

=B7 =20 Fracture = extending to=20 posterior vertebral cortex

=B7 =20 Retropulsed = fragment,=20

=B7 =20 Cord = compression,=20

=B7 =20 Radiculopathy, =

=B7 =20 Fever and/or=20 sepsis,

=B7 =20 Coagulopathy.

TECHNIQUE

Vertebroplasty=20 is a day-care procedure that is performed on an outpatient basis. The = procedure=20 is not painful and requires only mild sedation and analgesia. = Occasionally,=20 patients report pain when the trocar reaches the fracture fragments and = when the=20 injection of acrylic cement is initiated. However this can be tolerated = by most=20 patients without much discomfort. In an occasional uncooperative patient = general=20 anaesthesia may be indicated.

Lumbar=20 vertebroplasty consists of the transpedicular placement of an 11-gauge = bone=20 biopsy needle into the affected vertebra under fluoroscopic or CT = guidance.=20 Thoracic vertebroplasty is performed via 13-gauge bone biopsy needle. = Once=20 positioned, methylmethacrylate is injected through the needle into the = abnormal=20 vertebral body.

The = acrylic is=20 then prepared under sterile conditions for injection. The dry, powdered = polymer=20 is mixed with a liquid monomer of methylmethacrylate to a consistency = similar to=20 that of toothpaste. The acrylic cement is then injected with either a = 1-mL=20 Luer-Lok syringe through the trocar. Injection is continued until = complete=20 opacification of the vertebral body is achieved or the first sign of = extension=20 into the epidural venous plexus appears.

Opacification=20 of the paraspinous veins is common. When opacification occurs, the = injection of=20 acrylic is suspended for approximately 1 minute to allow the cement to = harden=20 within the vein. Injection may then be resumed, and the acrylic follows = a new=20 path of lower resistance.

Opacification=20 of the vertebral body need not be complete for successful = vertebroplasty. If the=20 acrylic reaches both the superior and inferior endplates and extends = across=20 midline, approximately 80% of the load-bearing benefit of a completely = opacified=20 vertebral body is achieved (Belkoff et al).

A = small amount=20 of methylmethacrylate is retained on the bench as a control. After = approximately=20 10 minutes, the cement solidifies and becomes harder than the native = bone. Once=20 the control sample has solidified, the Patient is examined for = neurological=20 deficit before being transferred to a post-operative ward.=20

RISKS =

The = risks of=20 the procedure are low, but they potentially include infection, worsening = of=20 pain, and neurological problems such as weakness or pain in the legs.=20 Occasionally, the acrylic may extend into the epidural or paraspinous = veins.=20 Cement in the epidural venous plexus may lead to an ascending venous = thrombosis=20 or contribute to a spinal stenosis or cord or nerve root compression. = Acrylic=20 may extend from the paraspinous veins into the vena cava and may result = in a=20 pulmonary embolus. The risk of venous embolization increases if the = operator=20 cannot adequately identify when the cement begins to pass into the = venous=20 system. This risk is reduced by using angiographic equipment with the = highest=20 resolution available. The visibility of methylmethacrylate is further = improved=20 with the addition of fine metallic powders such as barium mixed with = tantalum or=20 tungsten.

RESULTS=20

Approximately=20 85-90% of patients have rapid pain relief.

This = procedure=20 is associated with a low morbidity rate. Fewer than 1% of patients with = have=20 morbidity. Morbidity may include local pain, rib pain, spinal stenosis, = nerve=20 root compression, and intravascular extension of acrylic. =

In=20 approximately 90% of patients there is complete resolution of pain. = Incisional=20 and muscular pain may persist for the first few days after the procedure = and it=20 can be controlled with adequate oral anagesics. Point tenderness that is = noted=20 before the procedure has not been noted in any of the patients after the = procedure

Although pain=20 is reduced or eliminated after the procedure, patients must exercise = caution in=20 subsequent activities because other osteoporotic vertebral bodies may = also be=20 prone to fracture. Medical management of the underlying disorder that = weakens=20 the vertebral bodies should be initiated. This procedure does not = eliminate the=20 need for aggressive treatment of osteoporosis, without which other = fractures may=20 ensue.

3D"Click

Transpedicular=20 placement of a trocar in the anterior third of the fractured = vertebral=20 body

Lateral=20 radiograph of fractured vertebra shows the initial placement of = the=20 trocar

3D"Click

Injection=20 of methylmethacrylate through the trocar in anterior one third of = the=20 vertebral body.

Compression=20 fracture after = vertebroplasty.

Conclusions

Osteoporostic=20 vertebral fractures are common in elderly. These fractures reduce a = patient's=20 quality of life and shorten life expectancy. Several available = medications have=20 been shown to reduce the risk of fracture. In patients with unhealed = compression=20 fractures vertebroplasty may reduce or relieve pain in selected = patients.=20

BIBLIOGRAPHY

Belkoff SM, = Mathis JM,=20 Jasper LE: The biomechanics of vertebroplasty the effect of cement = volume on=20 mechanical behavior. Spine 2001 Jul 15; 26(14): 1537-41 =
Tohmeh AG, = Mathis JM,=20 Fenton DC: Biomechanical efficacy of unipedicular versus bipedicular=20 vertebroplasty for the management of osteoporotic compression = fractures. Spine=20 1999 Sep 1; 24(17): 1772-6
Wong W, = Reiley MA,=20 Garfin S: Vertebroplasty/kyphoplasty. J Womens Imaging 2000 Aug; 2(3): = 117-24.