Osteoporosis and spinal surgery: strategies for medical ... · help achieve successful fusion of...

REVIEW / Rev Osteoporos Metab Miner. 2018;10(1):41-5441

Díaz-Romero Paz R1, Reimunde Figueira P2

1 Servicio de Neurocirugía - Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria - Las Palmas de Gran Canaria (España)2 Servicio de Neurocirugía - Hospital Universitario Central de Asturias - Oviedo (España)

Osteoporosis and spinal surgery:strategies for medical and surgicaltreatment

DOI: http://dx.doi.org/10.4321/S1889-836X2018000100007

Correspondence: Ricardo Díaz-Romero Paz - Servicio de Neurocirugía - Complejo Hospitalario Universitario Insular-MaternoInfantil de Las Palmas de Gran Canaria - Avda. Marítima del Sur, s/n - 35016 Las Palmas de Gran Canaria (Spain)e-mail: [email protected]

SummaryThe prevalence of osteoporosis in patients undergoing spinal surgery is estimated at 50% in women over50 years, a higher figure than in the general population adjusted for age. Consequently, many authorsrecommend the systematic assessment and timely treatment of osteoporosis in most patients who aregoing to undergo arthrodesis.The decrease in bone mineral density (BMD) is the main factor in independent risk related to the failu-re of the instrumentation in spinal fusion surgeries.Complications arising from spinal fusion are more frequent in osteoporotic patients over 65. The most frequentearly complications are pullout or tearing pedicular screws, pedicular fracture and fracture by compression inthe adjacent vertebral segment. After 3 months, the most frequent complications are pseudoarthrosis, fractureor mobilization of the bars, subsidence of vertebral intersomatic boxes and the kyphosis of the proximal joint.There are some clinical trials of spinal arthrodesis surgery with perioperative treatment with alendrona-te, zoledronic acid, or teriparatide that have been shown to be effective in clinical improvement andincrease in fusion rates.Several modifications in the surgical arsenal may improve fusion rates and decrease surgical complica-tions. Arthrodesis has been highlighted with cemented and expandable pedicle screws. Finally, randomized clinical trials have shown that vertebral reinforcement treatments in osteoporotic ver-tebral fractures are beneficial in the short and long term.

Key words: osteoporosis, vertebral arthrodesis, lumbar spine, spinal fusion.


Bone metabolism and spinal disorderSpinal fusion surgeries with or without instrumen-tation have become well-established surgical pro-cedures in the therapeutic arsenal of spinal disea-se, either degenerative, deformity (scoliosis anddegenerative kyphosis), vertebral instability (dege-nerative spondylolisthesis and isthmus) and in ste-nosis of the lumbar spinal canal (central or forami-nal).

The gradual aging of the population has led toan increase in spinal fusion surgeries in elderlypatients. From 2001 to 2007, spinal fusion proce-dures in those insured by Medicare in the USAincreased 15 fold1. A significant percentage ofpatients who require lumbar or cervical vertebralarthrodesis are older than 50 years, many ofwhom suffer from osteoporosis without beingcorrectly diagnosed.

In Spain, approximately 2 million women sufferfrom osteoporosis, according to the densitometriccriteria proposed by the World Health Organization(WHO). Díaz-Curiel et al. estimated that the preva-lence of osteoporosis in Spain is around 26% (1 in4) of women over 50 years of age2.

In a recent study in patients over 50 years whounderwent spinal surgery, 41.4% of women werereported to have osteopenia and 51.3% had osteo-porosis. On the other hand, in men, 46.1% presen-ted osteopenia and 14.5% osteoporosis3,4. Thus, theprevalence of osteoporosis in women undergoingspinal surgery is higher than that of the generalpopulation adjusted for age. Consequently, manyauthors recommend the systematic evaluation andtimely treatment of osteoporosis, especially inwomen over 503.

Patients with osteoporosis present a lowerbone mineral density (BMD) and lower osteoblas-tic activity, which negatively influence osteocon-ductive, osteoinductive and osteogenic capacity.Therefore, patients with osteoporosis have increa-sed bone remodeling and negative final bonebalance, which results in poor bone fusion, and areduction in the force of extraction or pullout ofthe pedicle screws4.

Reduced BMD is the main independent riskfactor related to instrumentation failure in lumbarfusion surgeries4 and a moderate risk factor forthe development of pseudoarthrosis. BMD is sig-nificantly higher in patients who achieve higherfusion rates compared to those who suffered froma lack of fusion after vertebral column arthrodesis,according to some reports5. Although the develop-ment of pseudoarthrosis is multifactorial, a signifi-cant proportion could be explained by low BMDlevels6.

Complications in spinal surgery associatedwith osteoporosisArthrodesis with long instrumentation assembliesare increasingly common in the treatment of spi-nal deformity (scoliosis and degenerative kypho-sis). Scoliotic deformities are present in 36-48% ofosteoporotic women and patients with large defor-mities in the spine usually have a low BMD7.

Complications derived from spinal fusion surgerytend to be more frequent in patients over 65 andosteoporotic.

Early complications occur within the first 3months of surgery. The most frequent are thepullout or removal of the pedicle screws, epiduralhematoma, pedicular fracture and fracture of theadjacent vertebral segment by compressionmechanism7-10.

Late complications, after 3 months includepseudoarthrosis, fracture or mobilization of thebars, fracture by compression mechanism of theadjacent vertebral segment, pain in the iliac area(specifically in the area of insertion of the iliacscrews), disc herniation (mostly cephalic), subsi-dence of vertebral intersomatic boxes and proxi-mal junction kyphosis (PJK) (Figure 1).

Instrumentation failure may also be subdividedaccording to the location of the instrumentation,either anterior or posterior. The latter tends to faildue to a limited fixing force in the bone of lowdensity, which results in the extraction or pulloutand/or loosening of the pedicle screws11,12. In con-trast, anterior instrumentation is subject to a repe-titive cyclic load, resulting more frequently inscrew rupture or implant subsidence in patientswith BMD involvement12,13.

Osteoporosis is a major risk factor for the failu-re of surgery in the spine, and even more so whenmultiple vertebral levels are instrumented14,15.

De Wald et al.10 reported that the two most fre-quent mechanisms of complications in patientsover 65 years of age, operated on at least 5 levelsof instrumentation, were vertebral fracture bycompression mechanism of the last superior verte-bral segment of an arthrodesis and PJK to the lastinstrumented segment in 28% of cases. Other arti-cles concur that PJK is the most frequent compli-cation in multi-level instrumented columns16-18. Asa complication, PJK has provoked much interest inits frequency and complexity. The ScoliosisResearch Society defines proximal junctionalkyphosis (PJK) as the kyphotic Cobb angle equalto or greater than 20º between the last instrumen-ted vertebra and the two vertebrae located above(Figure 2). PJK occurs in 39% of operated deformi-ties occurring most between 6-8 postoperativeweeks. The three most important risk factors areadvanced age, poor bone quality and significantsagittal imbalance prior to surgery. Of all thepatients who develop PJK, approximately onethird are re-operated early before 5 months forsurgical revision due to mechanical failure andvertebral instability19.

It is important to consider that a preoperativethoracic kyphosis of more than 30º is an indepen-dent risk factor for the appearance of PJK, and thatthe adequate resolution of the sagittal imbalanceprior to surgery reduces the incidence of PJK from45% to 19%20.

Medical treatment strategiesPatients with osteoporosis and with uncorrectedhypovitaminosis D reported present worse rates of


bone fusion after vertebral arthrodesis and mayalso have poorer clinical results in disability scalesin the perioperative period4.

In recent decades there has been a significantadvance in the knowledge of the pathophysiologyof bone formation and resorption, as well as in thetreatment of osteoporosis, which logically leads usto wonder about the influence of these therapiesin the bone fusion process in spinal surgery21.Currently an increasing number of studies and cli-nical trials evaluate the impact of various pharma-cological treatments (bisphosphonates, zolendro-nic acid, PTH) on bone fusion in spinal surgeries.Table 1 summarizes the main studies to date.

In experimental animals, 18 studies have beenreported that assessed the influence of bisphos-phonates on the fusion process in arthrodesis,most of them did not demonstrate significanteffects on bone fusion rate probably attributed tolow statistical power. Studies in animals with bis-phosphonate-based therapy showed that the bonefusion mass was histologically less mature, howe-ver the impact on spinal biomechanics was notclear22.

On the other hand, in an osteoporotic animalmodel alendronic acid was found to be effectivein obtaining radiological, biomechanical and histo-

logical improvement of the fusion of the vertebralcolumn23. Alendronate increased the biomechani-cal strength with internal bone growth in the pos-terolateral fusion masses in the osteoporotic ani-mals. This study suggests that alendronate canhelp achieve successful fusion of the spine in ani-mals affected by osteoporosis.

Kim et al.24 studied the effect of alendronate in44 patients operated on 1-level instrumented inter-somatic lumbar fusion compared to the controlgroup without treatment. They did not find signi-ficant differences in terms of bone fusion, and ins-tead there was a higher incidence of vertebralplate degeneration in the alendronate group.

Nagahama25 published a clinical trial in 40patients with osteoporosis who underwent inter-somatic lumbar fusion and treatment with bis-phosphonates. There was an increase in the fusionrate at one year of follow-up in the alendronategroup compared to controls (95% vs 65%, respec-tively), in addition to reducing the presence ofsubsidence of the prosthesis and the vertebralfracture of the level adjacent. Finally, the authorsrecommend postoperative treatment with bisphos-phonates in all patients with osteoporosis,although they acknowledge that there is still noconsensus regarding the use of these drugs.

Figure 1. (A) Lateral radiograph of lumbosacral spine: S1 screw rupture is observed (arrow). (B) Surgical part ofthe broken screw removed. (C) side of the lumbosacral spine where mobilization bar distally (arrow) x. (D) CTaxial cut and (E) sagittal, hypodense halo is observed around the pedicle screws (arrows), characteristic of pseu-doarthrosis. (F) Sagittal CT that illustrates the presence of subsidence or subsidence of the intersomatic device,note the loss of the disc height and the erosion of the vertebral plates (arrow)


Park et al.26 in 2013 evaluated the effect of zoledro-nic acid in 44 patients with lumbar spinal stenosis ope-rated on posterolateral arthrodesis with instrumenta-tion of 1 or 2 levels, one group received a dose of zole-dronic acid and another group control. At 6 monthsafter surgery there was no significant increase in thefusion mass in the single-dose zoledronic acid groupdemonstrated by 3D computerized tomography.However, there was a significant improvement in theVisual Analogue Scale (VAS) and the Oswestry

Functional Scale (OFS) inthe zoledronic acid group.

Tu et al.27 also studiedthe effect of zoledronic acidon fusion rates in patientswith osteoporosis after pos-terior lumbar interbodyfusion at 2 years of follow-up. The zoledronic acidgroup received an intrave-nous infusion at 3 and 12months after surgery. Therewas a non-statistically signi-ficant difference in patientswith zoledronic acid with afusion rate of 75%, compa-red with 56% in the controlgroup. In addition, therewere better VAS and OFSscores, but without beingstatistically significant inpatients receiving zoledro-nic acid. The rates of pedi-cle screw loosening weresignificantly lower inpatients with zoledronicacid of 18% compared to45% in the control group.

Chen et al.28 conducteda recent randomized clini-cal trial on the effect ofzoledronic acid on bonefusion in patients with oste-oporosis after arthrodesis ofthe lumbar spine. They stu-died 79 patients with dege-nerative spondylolisthesisof 1 level. A greater fusionwas observed at 3, 6 and 9months in the zoledronicacid group without beingsignificant at 12 months.Zoledronic acid preventedbone loss induced byimmobilization and increa-sed BMD. The authors con-cluded that zoledronic acidshortens the time to achie-ve a bone fusion, and pre-vents subsequent vertebralcompression fracture. Thelimitations were the smallsample size and the shortfollow-up time.

Another randomized clinical trial was conduc-ted by Ohtori et al.29 in 57 women with osteopo-rosis and degenerative spondylolisthesis under-going a posterolateral arthrodesis procedure. Onegroup received risedronate and another parathy-roid hormone (teriparatide). The authors found afusion rate of 82% with PTH and 68% with risedro-nate; the time frame for carrying out bone fusionwas 8 months for PTH and 10 months with rise-dronate.

Figure 2. (A) Sagittal CT at the thoracolumbar level; osteoporotic compres-sion fracture at level D12 with segmental kyphosis is observed. (B)Arthrodesis through instrumentation with pedicle screws from D10 to L2,with significant kyphosis correction. (C) Lateral radiography: vertebral com-pression fracture at D10 level with kyphosis of the proximal junction andscrew pullout at level D10. (D) Extension of arthrodesis, superior to levelsD8 and D9 and inferior to levels L3 and L4, and correction of kyphosis


Tab

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. The

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44 p

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ss tha

n 5º

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with

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(1

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25)

Cor

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and

sag

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ate

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brid

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Zol

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Loc

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d au

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- G

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: 10

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Func

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Zol

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et al

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64 p

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with

OP

and

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spon

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oper

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of

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rsom

atic

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ion

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ledr

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IV (

n=32

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Con

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gro

up (

n=32

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post

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and

then

onc

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56%

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pend

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abse

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terv

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Zol

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79 p

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spon

dylo

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- Zo

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with

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gula

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par

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aO

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(201

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57 w

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ripar

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4% (

X-r

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and

82%

(CT)

- Ri

sedr

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4% (

RX)

and

68%

(TC

) (p

<0.

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sin

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and

int

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(201

3)30

62 w

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with

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- Te

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2 m

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and

10 a

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: th

ree-

dim

ensi

onal

.


In a more recent study, also by Ohtori et al.30, theeffect of teriparatide and risedronate on the incidenceof loosening of pedicle screws in patients operated oninstrumented posterolateral fusion with local bonegraft, specifically in 62 women with degenerativespondylolisthesis and osteroporosis. There was a sta-tistically significant difference in favor of the teripara-tide group in the loosening of screws (7-13%) compa-red with risedronate and the control group (15-26%).

Surgical strategies in the treatment ofosteoporotic patientsGiven the impact of osteoporosis on spinal fusioninterventions, techniques have been developedthat can increase the chances of successful verte-bral fusion surgery.

In developing these strategies, it is essential toconsider the most common forms of instrumenta-tion failure discussed in the previous section1.These techniques are:

1. Methods that reinforce the segmental verte-bral instrumentation

Increase of fixation points. The most commonmethod is to extend the instrumentation withpedicle screws at least 3 levels rostrally and cau-dally to the compromised level. In this way thestress that is transmitted to several fixation pointsis reduced; This is especially important in patientsover 65 with deformity or osteoporosis10.

Reports suggest that the addition of wires orsublaminar hooks to the pedicle screws, that is tosay hybrid assemblies, can significantly improvethe results of an arthrodesis in the osteoporoticspine31. Although this technique is an effectiveoption, it has not been widely used, probably dueto the technical difficulties involved.

Use of cross-link connector. This has been shownthat the addition of a transverse connector to the ins-trumentation with segmental pedicle screws increasesthe rigidity of the system and prevents the axial rota-tion of the instrumentation32. It has also been shownthat they increase the resistance to extraction orpullout of the pedicle screws. However, this effectwas substantially lower in the osteoporotic column33.

2. Technical modifications in the placementof screws

Pilot hole size. The creation of a pilot hole is thefirst step for the insertion of a pedicle screw. It isimportant to take into account the size of the pilothole, especially in the osteoporotic bone, since largepilot holes lead to poor grip of the screws, whilevery small pilot holes can increase the insertion tor-que, with the consequent risk of pedicle fracture.

Battula et al.34 attempted to characterize theoptimal size of the pilot orifice in the osteoporoticbone. Based on their results, the authors recom-mend the creation of a pilot hole no larger than71.5% of the outer diameter for maximum resistan-ce to pullout and minimize iatrogenic fracture ofthe pedicle, for which a more precise technique isrequired through high-speed milling, or the use ofa punch instead of a gouge.

Preparation of the screw path. Under normalconditions, tapping improves the insertion path ofthe pedicle screws; however, the tapping influen-ces the grip strength of the pedicle screws in theosteoporotic column.

Halvorson et al.35 found that the lack of tappingor tapping with diameters below 1 mm of the finaldiameter of the screw, led to a greater grip strengthof the pedicle screw.

Carmouche et al.36 observed similar results in astudy performed on corpses with osteoporotic bone:the tapping with the same diameter of the insertedscrew led to a decrease in the pull resistance of thelumbar pedicle screw. On the other hand, the non-tapping or tapping with a lower diameter showed agreater force required for the extraction of the lum-bar pedicle screws, although these differences werenot replicated with the thoracic pedicle screws.

Bi-cortical fixation of pedicle screws. As it isknown, the cortex of the vertebral body is signifi-cantly stronger compared to cancellous bone, sothat the bi-cortical attachment or hook is strongerthan the insertion in the spongy and uni-cortical.However, the bi-cortical fixation technique leadsto an additional risk of injury to neurological struc-tures, including the lumbar roots and the sacralsympathetic trunk; in vascular structures, such asthe aorta and the vena cava; and in the colon37.

Fixation with bi-cortical screws is usually carriedout ventrally or cranially to the superior plate of S1,where the risk of damaging neurovascular structuresis lower. It has been demonstrated that the latter tech-nique significantly increases the torsional force andthe extraction of the screw after a cyclic load compa-red with traditional anteromedially directed fixation38.

The screws in S1 can also be inserted in what isknown as a tricortical trajectory pointing towards theapex of the sacral promontory, so that the screw isinserted or meshed in the posterior cortex and ante-rosuperior of the superior plate of S1.

Hubbing involves inserting the screw to the headthat is embedded or abutted with the dorsal corticalbone of the vertebra, theoretically avoids the winds-hield-wiper effect of the instrumentation system.However, in a cadaveric biomechanical study of thistechnique, Paik et al.39 observed that hubbing led to areduction of more than 40% in the screw’s extractionforce, regardless of BMD, so it was not recommended.

The cortical bone screw is an alternative trajec-tory of the pedicle screw. The insertion of the pedi-cle screws with the traditional trajectory from dorso-lateral to ventromedial usually implies that thescrew thread is located in the cancellous bone of thevertebral body, which in osteoporotic patients maycause poor anchoring. An alternative trajectoryintroduced in 2009 is the placement of the screwwith a dorsomedial to ventrolateral trajectory, inorder to couple the screw with more cortical boneof the pars interarticular and of the pedicle40.

Although the trajectory of the screws placed withthe cortical bone tends to be smaller in diameterand shorter in length compared to traditional tech-niques, it has a reportedly greater insertion torqueand a greater extraction force of the screws41.


Currently, there is only one randomized clinicaltrial that compared screws in cortical bone with thestandard technique42. At 12 months, the fusion ratesevaluated by computerized tomography were simi-lar between the 2 groups (89.5%, n=39, in the con-ventional pedicle screw group and 92.1%, n=38, inthe group of cortical screw), with no differences inpain relief in the leg or scores in the Oswestry disa-bility index. However, subjects subjected to a corti-cal screw trajectory showed less blood loss, shortersurgical time, and a shorter incision length compa-red to their counterparts of conventional pediclescrews, probably due to the lack of need to exposebeyond the facet joint at the screw insertion points.

3. Modification in pedicle screw designIncrease in the size of the screws. One of the fun-damental techniques is the selection of longer ins-trumentation screws with a larger diameter. It isbelieved that the larger diameter screws "fill" morethe pedicle and allow a better contact of the screwthread with cortical pedicle. In addition to provi-ding a greater surface area of bone in contact withthe screw thread and obtain an additional impro-vement in fixation, particularly in the sacrum.There are several studies that have confirmed thatincreasing the diameter and length of the screwimprove the retention force of the screws43,44.

Tapered pedicle screws. Changes in the designof the screws have also been considered in termsof morphology and screw threading. The use ofconical screws, both with the conical thread andwith the center or conical core, are common. Ifthe outside diameter is constant, then the conicalcore allows a greater contact surface with the thre-ad of the screw in the spongy vertebral body,where the osteoporotic bone has little retentionpower45. Screws with a cylindrical outer diameterand conical internal diameter demonstrate a betterextraction force compared to other designs.

Cemented screws. One technique that has receivedconsiderable attention in recent years is the reinforce-ment of the pedicle screws through a cement layer ormantle around the screw at the level of the vertebralbody. This apparently distributes the tension of theadjacent trabecular bone so that the screws are lessprone to loosening or pullout46 (Figure 3).

This effect was demonstrated more thoroughlywith the use of polymethyl methacrylate (PMMA)47:there is an increase of between 2 to 5 times theforce of screw extraction in the osteoporotic verte-brae, a repeated finding in many studies. In thesame way, other bioactive cements constituted bycalcium sulphate or calcium phosphate have beenused with good results48.

There is a growing experience in the cementa-tion techniques of pedicular screws, and studies onits safety and efficacy have recently been reportedand summarized in table 2.

On the other hand, this technique involves risksderived from the use of cement. The main ones arecement extravasation at the venous level, with theconsequent possibility of embolism, and extravasa-tion in the spinal canal, with risk of neurological

injury. Fortunately, the vast majority of complica-tions are infrequent or asymptomatic49.

Expandable pedicular screws. Various modifica-tions have been tested in the design of screws forosteoporotic spinal fixation; These include expanda-ble screws and hydroxyapatite-coated screws. Theexpandable screws have a mechanism that allowsthe expansion of a part of the screw that is insidethe vertebral body, keeping the part of the pedicleintact (Figure 3). The screw compresses the cance-llous bone in the vertebral body as it expands,increasing the density of the bone around the screw.It has been possible to improve the pedicle fixationwith a 50% increase in the resistance to the extrac-tion of the screw in the osteoporotic bone50. Thiseffect was magnified when the expandable screwwas reinforced with bone cement51,52. One drawbackof this technique is the difficulty involved in revisionsurgeries that require removing expandable screws.

4. Strategies for the prevention of "proximaljoint kyphosis" (PJK)Regarding PJK prevention strategies, there is no cle-arly effective solution. Pre-operative assessment ofbone mass density is essential and timely correctionis possible. Other strategies related to the surgicaltechnique are: the adequate curving of the terminalbar in kyphosis, the placement of hooks in the trans-verse processes of the superior vertebra of the instru-mentation, and the avoidance of finishing the instru-mentation in a kyphotic vertebral segment. Minorcorrection of kyphosis is important but also maintai-ning an adequate sagittal and coronal balance.

Most authors advocate vertebroplasty at one ortwo levels higher than the instrumentation toavoid fracture or vertebral collapse in this suscep-tible segment. Table 3 summarizes the main surgi-cal strategies in the osteoporotic column.

Spinal reinforcement techniquesVertebroplasty and kyphoplasty are therapeutic pro-cedures that can be included within the so-called"spinal reinforcement techniques" and that arecarried out by interventional radiologists, by trauma-tologists or by neurosurgeons, percutaneously,usually with transpedicular approach. Percutaneousvertebroplasty involves introducing a bone cement,such as polymethylmethacrylate (PMMA), in a fractu-red vertebral body, to relieve pain by reinforcing andstabilizing the vertebral fracture (Figure 4). Similar tovertebroplasty, in percutaneous kyphoplasty, prior tothe administration of cement at the level of the frac-tured vertebra, a balloon is inserted that is inflated torestore the height of the vertebral body and reducekyphotic deformity. When the balloon is removed, acavity or nest remains inside the vertebral body, allo-wing the cement to be introduced at a lower pressu-re and with a higher viscosity, which reduces the riskof extravasation. Some authors prefer to call kypho-plasty "balloon vertebroplasty"53.

As has been amply demonstrated in the literatu-re and as it has been assured by different scientificsocieties, the use of vertebroplasty or kyphoplasty isa safe, effective and lasting procedure in selected


patients with symptomatic osteoporotic and neo-plastic fractures, as long as it is carried out accordingto published standards. These procedures must beoffered when non-surgical medical treatment hasnot provided adequate pain relief and this is signifi-cantly altering the quality of life of the patient54.

Multiple case series, retrospective and nonrando-mized prospective studies and, more recently, ran-domized controlled trials, have shown how thesetechniques achieve statistically significant improve-ments in pain and function, particularly in ambula-tion, with respect to medical treatment54.

There are currently a total of six randomizedcontrolled trials, including a total of 842 patients, inwhich the vertebral reinforcement treatment, verte-broplasty or kyphoplasty, is compared with medicalor simulated non-surgical treatment in osteoporoticvertebral fractures54 (Table 4).

The two randomized controlled trials with thelargest number of patients studied have shownbenefits for vertebroplasty and kyphoplasty thatlast up to 1 year after the intervention55,56.

Supporting these results,another study showedsignificant benefits forvertebroplasty thatpersisted up to 3 yearsafter treatment57. On theother hand, other inves-tigations have reportedbenefits of vertebro-plasty up to 1 monthafter intervention, butnot beyond this point58,61.The INVEST clinicaltrial showed a very sig-nificant trend towardsclinical improvementin relation to pain forthe group treated byvertebroplasty at thefirst month of treat-ment, despite the factthat no statisticallysignificant differenceswere achieved59. Onthe other hand, onlyone study failed todemonstrate that verte-broplasty treatmentwas beneficial after thefirst month after sur-gery60. Therefore, basedon these studies, wemay conclude that ver-tebral reinforcementtreatments in osteopo-rotic vertebral fracturesare clearly beneficial inthe short term and pro-bably also in the longterm54 (Table 4).

ConclusionsThe progressive aging of the population has signifi-cantly increased the procedures of spinal fusion. Theprevalence of osteoporosis in patients who undergosurgery ranges to around 50% in women over 50years of age. A significant proportion of these patientsare not adequately diagnosed with osteoporosis orvitamin D deficiency and, therefore, receive no timelytreatment. There is evidence that patients with osteo-porosis and with uncorrected hypovitaminosis Dhave worse results in cervical and lumbar disabilityscales. Patients with osteoporosis, having a poorbone mineral density, suffer from worse rates of bonefusion in spine arthrodesis.

Surgical complications are more frequent inpatients with osteoporosis, especially in those whodo not receive timely treatment and the relevant sur-gical technique modifications are not made.

Currently, a variety of pharmacological and surgi-cal medical treatment strategies are available that canimprove clinical outcomes and fusion rates ofpatients undergoing spinal fusion.

Figure 3. (A) CT axial cut and (B) sagittal pedicular screws are observed with thetechnique of vertebral reinforcement with cement. (C) and (D) Axial axial CTshows the technique with expandable screws, with part of the expanded screw atthe level of the vertebral body (arrow)


Tab

le 2

. St

udie

s th

at a

sses

s th

e ef

fect

of

diffe

rent su

rgic

al tec

hniq

ues

in p

atie

nts

with

ost

eoporo

sis

OP: ost

eoporo

sis;

PM

MA: poly

met

hyl

met

hac

ryla

te; X-r

ay: ra

dio

grap

hy;

CT: co

mpute

d tom

ogr

aphy;

2-, 3

-D: bi-trid

emen

sional

.

Pati

ents

Tech

niq

uesu

rgic

alR

ates

of

fusi

onM

eth

ods

offu

sion

rat

ing

Can

nul

ated

an

d ce

men

ted

scre

ws

Moo

n e

t al

.2237

pat

ient

s w

ith O

P an

dsp

inal

can

al s

teno

sis

dege

nera

tive

Can

nula

ted

and

cem

ente

d sc

rew

s w

ithPM

MA

91.9

%X-r

ayw

ith int

erso

mat

ic b

ony

brid

ges,

abs

ence

of

mov

emen

ts in

func

tiona

l st

udie

s, a

bsen

ce o

fra

diol

ucen

t pa

ttern

Piñ

era

et a

l.2223

pat

ient

s w

ith O

P >7

0 ye

ars,

lum

bar

spon

dylo

listh

esis

dege

nera

tive

and

inst

abili

tyor

lum

bar

sten

osis

Inst

rum

enta

tion

of c

annu

late

d sc

rew

san

d ce

men

ted

with

PM

MA

- 74

% (X-r

ay)

- 10

0% (CT

afte

r 6

mon

ths)

- Ra

diol

ucen

tity

at the

int

erfa

cece

men

t sc

rew

in

3 pa

tient

s

X-r

ayw

ith int

erso

mat

ic b

ony

brid

ges

CT

bony

brid

ges

inte

rtra

nsve

rso

or int

erfa

ceta

rio

Dai

et

al.22

43 p

atie

nts

with

OP

and

dege

nera

tive

illne

sssp

inal

Inst

rum

enta

tion

of c

annu

late

d an

dce

men

ted

scre

ws

100%

CT

in 2

- and

3-D

usi

ng th

e m

etho

ds o

f Sap

kas'

and

Chr

istia

nsen

's

Exp

anda

ble

ped

icle

scr

ews

Coo

k et

al.51

145

patie

nts

stud

ied;

21 h

ad O

PEx

pand

able

ped

icle

scr

ews

(Om

ega2

1 sp

inal

sys

tem

)86

%X-r

ayde

mon

stra

ting

trab

ecul

ar b

one

brid

ges

bet-

wee

n th

e fu

sed

segm

ents

Gaz

zeri

et

al.51

10 p

atie

nts

with

OP

Expa

ndab

le p

edic

le s

crew

s(O

sseo

Scre

w)

0% s

crew

loo

seni

ngX-r

ayan

d CT

to a

sses

s ra

diol

ucen

cy a

roun

dsc

rew

s

Wu

et a

l.5115

7 pa

tient

s w

ith s

teno

sis

of c

hann

el a

nd O

PEx

pand

able

ped

icle

scr

ews:

n=8

0Con

vent

iona

l sc

rew

s: n

=77

- Ex

pand

able

: 92

.5%

- Con

vent

iona

l: 80

.5%

(p=0

.048

)

RX d

ynam

ics

CT

blin

dly

eval

uate

d by

2 ra

diol

ogis

ts.

Fusi

on =

tra

becu

lar

bone

thr

ough

the

fus

edse

gmen

ts. Tr

ansl

atio

n <3

mm

or

angu

latio

n<5

mm

in

flexi

on-e

xten

sion

RX


Conflict of interests: The authors declare no con-flict of interest.

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14. Healy JH, Lane JM. Structural scoliosis in osteoporoticwomen. Clin Orthop. 1985;195:216-23.

15. Chesnut CH III, Silverman S, Andriano K, Genant H,Gimona A, Harris S, et al. A randomized trial of nasalspray salmon calcitonin in postmenopausal women withestablished osteoporosis: the prevent recurrence of osteo-porotic fractures study. Am J Med. 2000;109:267-76.

16. Cook SD, Salkeld S, Stanley T, Faciane A, Miller SD.Biomechanical study of pedicle screw. Fixation inseverely osteoporotic bone. Spine J. 2004;4:402-8.

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31. Tan JS, Kwon BK, Dvorak MF, Fisher CG, Oxland TR.Pedicle screw mo-tion in the osteoporotic spine afteraugmentation with laminar hooks, sublaminar wires,or calcium phosphate cement: a comparative analysis.Spine (Phila Pa 1976). 2004;29(16):1723-30.

32. Brodke DS, Bachus KN, Mohr RA, Nguyen BK.Segmental pedicle screw fixation or cross-links in mul-tilevel lumbar constructs. a biomechanical analysis.Spine J. 2001;1(5):373-9.

33. Suzuki T, Abe E, Okuyama K, Sato K. Improving thepullout strength of pedicle screws by screw coupling.J Spinal Disord. 2001;14(5):399-403.

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Table 3. Surgical beads to maximize the results of spine surgery in patients with osteoporosis.

1. The prevention and timely treatment of osteoporosis is the most important principle.2. Early assessment by the osteoporosis specialist for the preoperative optimization of osteoporosis.3. Longer instrumentation assemblies to avoid starting or terminating the instrumentation in the

cervicothoracic or thoracolumbar junction or in a kyphotic segment.4. Include at least three fixation points above and below the vertex of the deformity.5. Hybrid constructions (pedicle screws, hooks, wires) can improve strength. Fixing. Fixation with

iliac and sacral screws in long fusion constructions is recommended, thus maximizing stability.6. The support of previous column increases the distribution of load, decreases the tension in the

instrumentations via later.7. The direction of insertion of the pedicle screw affects the extraction force or pullout, so ancho-

ring or grasping in the subchondral bone (eg, sacral promontory) is recommended to maximizefixation.

8. The tapping with lower diameter increases the insertion torque and the extraction force orpullout of the pedicle screw.

9. Avoid the hubbing of the pedicle screws since it negatively affects the extraction force orpullout.

10. The use of vertebral reinforcement techniques with cemented or expandable screws can improvethe clinical radiological results.

Figure 4. MRI sequence T2 (A) and (B) T1: vertebral fracture is observed by acute compression at level D7with vertebral body edema. (C) Lateral X-ray of the dorsal spine shows vertebral wedging at level D7 with dis-crete segmental kyphosis. (D) Vertebroplasty of the fractured level with improvement of segmental kyphosis.(E) Lateral X-ray of follow-up, refracture with vertebral collapse of D7 and a significant segmental kyphosis isobserved. (F) Rescue surgery by arthrodesis with cemented pedicle screws from D5 to D9, with correction ofkyphosis


Tabl

e 4.

Ran

dom

ized

con

trol

led

tria

ls c

ompar

ing

verteb

ral re

info

rcem

ent trea

tmen

t, ve

rteb

ropla

sty

or k

ypho

pla

sty,

with

med

ical

or

sim

ulat

ed n

on-s

urgi

cal trea

tmen

t, in

ost

eo-

por

otic

ver

tebr

al fra

ctur

es

RPCS:

ran

dom

ized

and p

rosp

ectiv

e co

ntrolle

d s

tudie

s; V

AS:

Vis

ual

Anal

og

Scal

e; V

FC: ve

rteb

ral frac

ture

-com

pre

ssio

n; FR

EE: Fr

actu

re R

educt

ion E

valu

atio

n T

rial

; IN

VEST

:In

vest

igat

ional

Ver

tebro

pla

sty

Safe

ty a

nd E

ffic

acy

Trial

; M

RI: m

agnet

ic r

esonan

ce.

RP

CS

nIn

clus

ion

cri

teri

aG

roup

sPa

ram

eter

sTr

acki

ng

tim

e

Res

ults

(in

rel

atio

n t

o th

e "v

erte

brop

last

y"gr

oup

)

FREE

(20

09)

300

1-3

VFC

; at l

east

1 w

ith e

dem

a( M

RI)

and

loss

>15

% o

f he

ight

;<3

mon

ths

of th

e frac

ture

Kyp

hopl

asty

(n=

149)

vs

med

ical

tre

atm

ent (n

=151

)

- M

ain:

Sho

rt-F

orm

-36

phys

ical

com

pone

ntsu

mm

ary

(SF-

36 P

CS)

.-

Seco

ndar

y: p

ain

back

and

disa

bilit

y

12 m

onth

s

Sign

ifica

nt c

linic

al im

prov

emen

t at

the

firs

tm

onth

(p<

0.00

1).

Sign

ifica

nt c

linic

al im

prov

emen

t in

bac

k pa

inan

d di

sabi

lity

per

year

.N

o di

ffer

ence

s in

rel

atio

n to

adv

erse

effec

ts.

INV

EST

(201

2)13

11-

3 VFC

; <1

2 m

onth

s of

fra

ctur

e;Pa

tient

s w

ith m

alig

nant

tum

orpa

thol

ogy

are

excl

uded

Verteb

ropl

asty

(n=

68)

vspl

aceb

o (n

=63)

Mod

ified

Rol

and-

Mor

ris

Dis

abili

ty Q

ues

tion

nai

re(R

DQ

) an

d in

ten

sity

of

pain

in th

e fir

st m

onth

12 m

onth

s

No

sign

ifica

nt d

iffer

ence

s in

the

prim

ary

para

-m

eter

s at

the

first

mon

th, a

lthou

gh th

ere

wer

ecl

inic

al d

iffer

ence

s in

rel

atio

n to

pai

n in

tens

ityat

the

first m

onth

(p=

0.06

).N

o di

ffere

nces

in r

elat

ion

to a

dver

se e

ffect

s

Buc

hbi

nde

r et

al.

(200

9)78

1-2

VFC

; at

lea

st 1

with

ede

ma

(MRI

) or

vis

ible

fra

ctur

e lin

e;<1

2 m

onth

s of

the

fra

ctur

e

Verteb

ropl

asty

(n=

38)

vspl

aceb

o (n

=40)

Gen

eral

pai

n at

3 m

onth

s6

mon

ths

No

sign

ifica

nt d

iffer

ence

s be

twee

n th

egr

oups

at an

y tim

e du

ring

the

follo

w-u

p

Rou

sin

g et

al.

(200

9 y

2010

)49

1-3

VFC

; <8

mon

ths

of f

ract

ure;

Patie

nts

with

mal

igna

nt tum

orpa

thol

ogy

are

excl

uded

Verteb

ropl

asty

(n=

25)

vsm

edic

al tre

atm

ent (n

=24)

- M

ain:

int

ensi

ty o

f th

epa

in (

VAS)

at 3

and

12 m

onth

s.-

Seco

ndar

y: s

cale

sfu

nctio

nal

12 m

onth

s

No

sign

ifica

nt d

iffer

ence

s in

rel

atio

n to

pai

n or

func

tiona

l sca

les

at 3

and

12

mon

ths.

Sign

ifica

nt d

iffer

ence

s in

rel

atio

n to

pai

n at

the

first m

onth

(p<

0.01

)

VER

TOS

II (

2010

)20

2

1-3

VFC

; at

lea

st 1

with

ede

ma

(MRI

) an

d lo

ss >

15%

of

heig

ht;

<6 m

onth

s of

fra

ctur

e; P

atie

nts

with

mal

igna

nt tum

or p

atho

logy

are

excl

uded

Verteb

ropl

asty

(n=

101)

vs

med

ical

tre

atm

ent (n

=101

)

- M

ain:

int

ensi

ty o

f th

epa

in (

VAS)

to

the

first

mon

th a

nd 1

2 m

onth

s.-

Seco

ndar

y: a

naly

sis

ofco

st e

ffec

tiven

ess

12 m

onth

sSi

gnifi

cant

diff

eren

ces

in r

elat

ion

to the

inte

nsity

of

pain

at al

l tim

es o

f fo

llow

-up,

with

an

acce

ptab

le c

ost

Farr

okh

i et

al.

(201

1)82

1-4

VFC

; ve

rteb

ral ed

ema

(MRI

);pa

in p

rese

nt b

etw

een

4 w

eeks

and

10 m

onth

s; o

steo

poro

sis

dem

onst

ra-

ted

by d

ensi

tom

etry

Verteb

ropl

asty

vs

med

ical

trea

tmen

t.Cro

ssin

g w

as a

llow

ed f

rom

the

grou

p trea

ted

afte

r th

efir

st m

onth

Inte

nsity

of

pain

(VA

S);

Osw

estry

Dis

abili

ty I

ndex

;he

ight

of

the

verteb

ral

body

; de

gree

of

kyph

osis

36 m

onth

s

Sign

ifica

nt im

prov

emen

t in

rel

atio

n to

pai

n at

all tim

es a

fter

6 m

onth

s an

d in

rel

atio

n to

the

Osw

estry

Dis

abili

ty I

ndex

at al

l tim

es a

fter

3ye

ars.

Sign

ifica

nt im

prov

emen

t at

all

times

in

rela

-tio

n to

rad

iolo

gica

l pa

ram

eter

s


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