ORIGINAL ARTICLE

Analysis of recurrent fracture of a new vertebralbody after percutaneous vertebroplasty in patients

with osteoporosisos4_74 119..123

Hua Lin MD, Li-hua Bao MD, Xiu-fen Zhu MD, Cheng Qian MD, Xin Chen MD, Zu-bin Han MD

The Center of Research for Metabolic Bone Disease and The Affiliated Drum Tower Hospital of Medical School, Nanjing University,Nanjing, China

Objective: To investigate the characteristics of recurrent fracture of a new vertebral body after percutaneous verte-broplasty in patients with osteoporosis.

Methods: 29 postmenopausal osteoporosis patients were divided into two groups: 14 patients with recurrent fractureof a new vertebral body after vertebroplasty comprised the new fracture group and there were15 patients withoutrecurrent fracture in the control group. The following variables were reviewed: age, body mass index (BMI), history offractures, history of metabolic disease, anti-osteoporosis therapy, type of back brace used, bone mineral density (BMD)of the lumbar spine and hip, intact parathyroid hormone (iPTH), serum calcium and phosphorus, and time sincevertebroplasty.

Results: Compared with the control group, patients in the new fracture group were statistically significantly differentwith respect to BMI (t = 2.538, P = 0.027), BMD of the lumbar spine (t = 2.761, P = 0.015), BMD of the hip (t = 2.367,P = 0.037) and iPTH (t = 2.711, P = 0.017). Twelve (86%) of the 14 patients’ new vertebral fractures occurred within sixmonths after treatment of the initial fracture, and 10 (71%) fractures were adjacent to those previously treated bypercutaneous vertebroplasty.

Conclusions: A substantial number of patients with osteoporosis develop new fractures after vertebroplasty; two-thirds of these new fractures occur in vertebrae adjacent to those previously treated. The following variables influence theoutcome: BMI, history of fractures, history of metabolic diseases and medications, BMD of lumbar spine and hip,anti-osteoporosis therapy, and use of back brace.

Key words: Compression; Fractures; Minimally invasive; Osteoporosis; Surgical procedures

Introduction

Vertebral fracture is the commonest osteoporotic frac-ture, and vertebroplasty is the most commonly used andeffective surgical treatment for managing osteoporoticfracture pain. However recurrent fracture after surgery is acommon complication which is challenging to address.The purpose of this study was to analyze and discuss thecauses and contributing factors in occurrence of recurrentfracture after vertebroplasty, and to highlight the mattersthat need attention and the corresponding surgical mea-sures that should be implemented.

Materials and methods

PatientsTwenty-nine postmenopausal osteoporosis patients

who had undergone percutaneous vertebroplasty for asingle level of vertebral compression fracture participatedin our survey. All of them underwent dual energy X-rayabsorptiometry examination which showed that theirlumbar spine (L2–4) t-values were less than -2.5 standarddeviations (SD).

GroupsIn the new fracture group there were 14 patients with

an average age of 67.9 � 9.7 years (range, 56–77 years) andan average duration of menopause of 18.7 � 5.9 yearswith recurrent fracture of a new vertebral body after per-cutaneous vertebroplasty. In this group, all subjects deniedthat their recurrent fracture was related to trauma. Fifteenpatients with an average age of 69.6 � 10.8 years (range,

Address for correspondence Hua Lin, MD, The Center forResearch for Metabolic Bone Disease and The Affiliated Drum TowerHospital of Medical School, Nanjing University, Nanjing, China210008 Tel: 0086-25-83105188; Fax: 0086-25-83105187; Email:lh2116@126.com

Received: October 19 2009; accepted 8 February 2010DOI: 10.1111/j.1757-7861.2010.00074.x

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54–79 years) and an average duration of menopause19.1 � 7.6 years and without recurrent fracture of anew vertebral body after percutaneous vertebroplastywere selected to comprise the control group. To ensureaccuracy and comparability of the vertebral bone mineraldensity (BMD) measurements, the sites of the originalosteoporotic or recurrent fractures of the 29 patients weselected were all in the first lumbar vertebra (L1).

VariablesThe following variables were assessed: (i) patient’s

general characteristics including age, duration of meno-pause, and body mass index (BMI); (ii) comparison ofpatient’s history of present and past illnesses especiallywith respect to metabolic disease, multiple fractures, dateafter vertebroplasty, anti-osteoporosis and metabolic drugtherapy, use of back brace, and so on; (iii) patient’s bonedensitometry, the BMD of lumber (L2–4) and total hipbeing assessed by dual energy X-ray bone densitometry(Lunar-Dpx-IQ, GE, Wauwatosa, WI, USA) and thet-values for lumber spine and hip calculated; and (iv) dateand site of the new fracture.

Statistical analysisStudent’s t-test was used for comparison between the

two groups of the measurement indexes. All differences

are regarded as significant only if P < 0.05. SAS 8.0 statis-tical software was used for statistical analysis.

Results

Factors influencing recurrent fractureafter vertebroplasty

Comparing the new fracture group with the controlgroup, we found that a history of multiple fractures, use ofdrugs which influence bone metabolism such as glucocor-ticoids, diseases of the endocrine or immune systems,anti-osteoporosis therapy after vertebroplasty and appli-cation of a lumbar back brace were the factors whichcorrelated with recurrent fracture (Table 1).

Comparison of the general characteristics and BMD ofpatients showed that there were no statistically significantdifferences between the two groups in age, duration ofmenopause, follow-up time after vertebroplasty, andserum calcium and phosphate concentrations. However inthe new fracture group, the BMI were notably lower thanin the control group (P = 0.027), hip and lumbar densitiesand t-values were significantly less than in the controlgroup (P < 0.05), and serum parathyroid hormone (PTH)concentrations were greater than in the control group (P =0.017, Table 2). These results indicate that patients who

Table 1 Confounding variables of patients in the two groups [cases (%)]

Factors New fracture group (n = 14) Control group (n = 15)

Multiple fractures 7 (50) 2 (13)Use of drugs which influence bone metabolism 5 (36) 1 (7)History of metabolic disease 6 (43) 1 (7)Multiple vertebral fractures 5 (36) 4 (27)Anti-osteoporosis therapy 3 (21) 9 (60)Use of back brace 2 (14) 8 (53)

Table 2 BMD and baseline comparison of outcome of patients in the two groups

New fracturegroup (n = 14)

Control group(n = 15) t value P value

Age (years) 64.67 � 7.10 66.08 � 7.90 1.324 0.213Duration of menopause (years) 13.76 � 4.50 15.09 � 5.20 1.782 0.096BMI (kg/cm2) 22.79 � 2.78 24.99 � 3.56 2.538 0.027Time since surgery (days) 476.30 � 21.83 489.06 � 26.51 1.799 0.084L2–4 BMD (g/cm2) 0.741 � 0.159 0.825 � 0.147 2.761 0.015L2–4 t-value -3.20 � 0.27 -2.60 � 0.21 2.913 0.011Hip BMD (g/cm2) 0.647 � 0.139 0.756 � 0.167 2.367 0.037Hip t-value -2.30 � 0.19 -1.90 � 0.14 2.510 0.023iPTH (pmol/l) 9.71 � 0.84 5.02 � 0.25 2.711 0.017Serum calcium (mmol/l) 2.37 � 0.15 2.29 � 0.18 1.997 0.610Serum phosphate (mmol/l) 1.35 � 0.11 1.49 � 0.13 2.014 0.577

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are thinner, and who have lower BMD of the lumbar spineor hip and higher PTH concentrations have a higher riskof new bone fractures.

Time of occurrence of the new fractureMost new fractures occurred within six months of ver-

tebroplasty. Seven new fractures occurred within 3months of surgery, five within 3–6 months, one within6–9 months, and one after 12 months.

Incidence of new fracture in adjacent vertebraeIn 10 of the 14 cases (71.4%) the new fracture occurred

adjacent to the previously treated vertebra, whereas therate of non-adjacent fracture was 28.6% (4 cases). Thisindicates that new fractures occur much more frequentlyadjacent to the treated vertebra after vertebroplasty thanelsewhere. None of the X-ray films of the 14 patients withnew vertebral fracture showed any leakage of bone cementafter vertebroplasty (Fig. 1).

Discussion

The new minimally invasive technique of vertebro-plasty for treatment of painful osteoporotic vertebralfracture can quickly relieve pain, improve function andrestore the integrity of the spine. During 30 years of clini-cal application, it has achieved satisfactory curative effi-cacy. However the incidence of new vertebral fracture aftersurgery is a common clinical problem, having beenreported to be 13.68–20.6%1,2.

The causes of new fracture after vertebroplastyOsteoporosis, one of the risk factors in fractures of the

elderly, makes treatment after fracture difficult, so ways of

improving the quality of fracture treatment and prevent-ing new fractures is at the heart of present work on treat-ment of fractures in the elderly 3. The reasons for newfractures occurring after vertebroplasty for osteoporoticvertebral fractures can be divided into two categories, thebiological causes of osteoporosis and the biomechanics ofthe vertebroplasty technique. Progression of osteoporosiswill result in further deterioration of bone quality, andconsequentially lead to recurrent fracture. Vertebroplastyalways induces some chemical and physical changes in theskeleton which can lead to new fractures as a result ofbiomechanical changes. Therefore the incidence of newvertebral fractures after vertebroplasty for osteoporoticvertebral fractures should be analyzed from various anglesin order to establish effective methods for preventingrecurrent fracture.

Factors related to osteoporosisVertebral fracture is the most common osteoporotic

fracture, it can occur repeatedly, and is attributed to theosteoporosis itself. So we should assess the severity of theosteoporosis concurrently with undertaking fracturetreatment and take care to choose the appropriate surgicalmeasures. The assessment of an osteoporotic fracture andthe severity of the osteoporosis should include omnifari-ous factors, such as the patient’s BMI, BMD, bone turn-over indexes4. Our study suggests that individuals who arethin and who have reduced BMD of the lumbar spine orhip and increased PTH concentrations are at greater riskof new bone fractures after vertebroplasty. Patients withprogressive osteoporotic fractures who have obviouslyabnormal bone turnover indexes, high PTH concentra-tions or secondary hyperparathyroidism (SHPT) should

A B

Figure 1 Plain lateral radiographs of a67-year-old female patient who experi-enced acute back pain when she bent overat home. The X-ray films showed a thoracicvertebral fracture (T6). She then underwentvertebroplasty to relieve her pain, thesurgery was successful resulting in goodpain relief. When she returned for routinefollow-up on the fortieth day, the X- rayfilms showed a new fracture of T7, imme-diatley adjacent to her initial fracture. (A)The day of surgery. (B) Forty days aftersurgery.

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be prescribed osteoporosis treatment while their fracturesare being treated, otherwise not only will fracture healingbe delayed, but new fractures will inevitably occur. Studieshave showed that the incidence of new fractures variesaccording to whether the patients receive an anti-osteoporosis treatment after vertebroplasty1. Prescriptionof glucocorticoids also plays an important role in newfractures2.

Factors related to vertebroplastyand countermeasures

As well as comprehensively analyzing the skeletal statusand prioritizing assessment of bone turnover indexes andBMD, the whole situation of the patient, including theextent of osteoporosis, should be taken fully into accountbefore instituting surgical therapy. If we focus only on thepresenting fracture and ignore the root cause, new frac-tures will be inevitable postoperatively. It is remarkablethat surgery is more effective when a preoperative MRIshows a fresh fracture. Yang et al. have pointed out thatselective individual vertebroplasty treatment producesa satisfactory result and prevents recurrent fracturepostoperatively5.

How to correctly apply filling technology is a key pointin surgery involving the use of bone cement. A study of 83patients, which used logistic regression analysis for 13different factors to evaluate the relative risks of recurrentcompressed fractures, has shown that leakage of bonecement into the discs is the only independent factor thatpredicts the incidence of new fracture after vertebro-plasty6. They found that factors such as age, sex, BMD,number of vertebroplasty operations, number of verte-brae operated on during a single procedure, accumulatednumber of surgically treated vertebrae, presence of asingle or multiple untreated vertebrae during surgery,quantity of cement injected each time, accumulatedamount of bone cement injected, leakage of bone cementinto soft tissue around the vertebra and leakage of cementinto veins do not correlate with an increased risk of newfracture6. However most scholars believe that multiplefactors determine the occurrence of new fracture1,2,7,8.

In this study, the new fracture was adjacent to the pre-viously surgically treated vertebrae in 10 of 14 patients(71%). This incidence is significantly higher than for non-adjacent vertebrae. Hulme et al. analyzed their results andpointed out that kyphoplasty and partial vertebroplastycan restore the height of the compressed vertebra7. Theirrates of bone cement leakage after vertebroplasty andkyphoplasty were 41% and 9%, respectively7. The inci-dence of adjacent vertebral fractures after these twooperations is higher than for general osteoporosispatients, yet close to that of patients with a history of

vertebral fracture. A study from the Beth Israel DeaconessMedical Center in Boston found that, among 177 patientswho had undergone vertebroplasty, 22 (12.4%) experi-enced a total of 36 new vertebral fractures, among which24 new fractures (67%) occurred adjacent to the previ-ously surgically treated vertebra, while the other 12 (33%)were in non-adjacent vertebrae. They believed the reasonfor this disparity was that percutaneous vertebroplasty canreinforce a vertebra and increase its rigidity. This changein rigidity might create increased disparity in the rigidityof neighboring vertebrae, alter the distribution of pressurebetween them, and thus increase the risk of fracture ofadjacent vertebrae8. In studies of biomechanical changesin adjacent vertebrae after kyphoplasty with calciumphosphate cement, scholars have confirmed that the stressand strain values increase differently in the adjacent inter-vertebral discs, non-enhanced vertebrae and back struc-tures including the posterior vertebral bodies and thepedicles of the vertebral arches; and the increment of non-enhanced vertebrae is most significant. The influence ofenhanced vertebrae to the neighboring vertebrae issimilar, which may lead to the highest incidence of newfracture9.

Our study suggests that the rate of new fractures ishigher in the first six months after vertebroplasty than atother times, 12 of the 14 patients (86%) experienced newfractures within six months of surgery. Uppin et al.reported that, of 36 new fractures, 24 (67%) occurredwithin 30 days of the first fracture therapy8. Komemushiet al. found that the rate of new fractures within 90 days ofvertebroplasty was about 10%6. Therefore, great impor-tance should be attached to preventing new fracturesin the first six, especially the first three, months aftervertebroplasty.

Other measurementsWith regard to osteoporotic therapy, application of a

back brace and rehabilitation activities can also signifi-cantly affect the incidence of new vertebral fractures aftervertebroplasty. In this study, treatment of osteoporosisand application of a back brace were implemented muchmore often in the control group. Because of the rapidimprovement in symptoms after vertebroplasty, patientsmay undertake inappropriately strong physical activities,which can be another cause of recurrent fracture8.However when patients perform exercises for the waistmuscles, especially the back extensor muscle, after verte-broplasty, the incidence of new fractures is markedlydecreased10.

In conclusion, the incidence of new vertebral fracturesis related not only to osteoporosis itself but also to theinfluence of the vertebroplasty. The first three months

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after vertebroplasty is an important time window. The hipand vertebral BMD, treatment of anti-osteoporosis, use ofa back brace, and correct rehabilitation training are alsoimportant factors affecting the incidence of new vertebralfractures.

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bral kyphoplasty. Spine J, 2006, 6: 488–493.2. Syed MI, Patel NA, Jan S, et al. Symptomatic refrac-

tures after vertebroplasty in patients with steroid-induced osteoporosis. AJNR Am J Neuroradiol, 2006,27: 1938–1943.

3. Huang GY. Clinical treatment of geriatric fractures tobe improved (Chin). Zhonghua Chuang Shang Gu KeZa Zhi, 2004, 6: 961–962.

4. Lin H, Bao LH, Han ZB, et al. The effects of calci-tonin treatment on bone quality in patients withosteoporosis (Chin). Zhonghua Gu Ke Za Zhi, 2001,21: 519–521.

5. Yang HL, Gu XH, Chen L, et al. Selectivity and indi-vidualization of transpedicular balloon kyphoplasty

for aged osteoporotic spinal fractures (Chin). Zhong-guo Yi Xue Ke Xue Yuan Xue Bao, 2005, 27: 174–178.

6. Komemushi A, Tanigawa N, Kariya S, et al. Percutane-ous vertebroplasty for osteoporotic compression frac-ture: multivariate study of predictors of new vertebralbody fracture. Cardiovasc Intervent Radiol, 2006, 29:580–585.

7. Hulme PA, Krebs J, Ferguson SJ, et al. Vertebroplastyand kyphoplasty: a systematic review of 69 clinicalstudies. Spine, 2006, 31: 1983–2001.

8. Uppin AA, Hirsch JA, Centenera LV, et al. Occurrenceof new vertebral body fracture after percutaneousvertebroplasty in patients with osteoporosis. Radiol-ogy, 2003, 226: 119–124.

9. Mao HQ, Yang HL, Chen L, et al. Biomechanical evalu-ation of kyphoplasty with calcium phosphate cement(Chin). Suzhou Da Xue Xue Bao, 2007, 27: 17–20.

10. Huntoon EA, Schmidt CK, Sinaki M. Significantlyfewer refractures after vertebroplasty in patients whoengage in back-extensor-strengthening exercises.Mayo Clin Proc, 2008, 83: 54–57.

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