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COMMENTARY
Year : 2017  |  Volume : 65  |  Issue : 1  |  Page : 96-98

Spinal surgery in patients with significant osteoporosis: The therapeutic advances and research perspectives


1 Department of Endocrinology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
2 Department of Endocrinology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India

Date of Web Publication12-Jan-2017

Correspondence Address:
Sushil K Gupta
Department of Endocrinology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.198245

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How to cite this article:
Gupta SK, Singh R. Spinal surgery in patients with significant osteoporosis: The therapeutic advances and research perspectives. Neurol India 2017;65:96-8

How to cite this URL:
Gupta SK, Singh R. Spinal surgery in patients with significant osteoporosis: The therapeutic advances and research perspectives. Neurol India [serial online] 2017 [cited 2017 Sep 24];65:96-8. Available from: http://www.neurologyindia.com/text.asp?2017/65/1/96/198245


Osteoporosis and osteoporotic fractures occur commonly in the elderly populations across the globe as well as in India.[1],[2],[3] Spinal fixation surgery is frequently required in the elderly patients with osteoporosis for a variety of indications, e.g., spondylolisthesis, vertebral fractures, and vertebral deformities.[4] Such surgical interventions require several modalities of vertebral fixation devices including bone screws and plates.[5],[6] A major dilemma with such surgery is whether or not the screw will be held in place in such a fragile bone. There have been significant advancements in the biomechanical properties of instrumentation, such as the advances seen in the pedicle screws, and various types of bone cement have been utilised for augmenting the strength of the area around the inserted screw in a specific vertebral body.[6]

The study by Chandra el al., in this issue highlights the efficacy of use of fenestrated pedicle screws augmented by polymethylmethacrylate (PMMA) in the vertebral bodies in 25 individuals with osteoporosis and spondylolisthesis. They reported that fenestrated pedicle screw fixation with bone cement augmentation in patients with lumbar spondylolisthesis and osteoporosis provided effective and lasting screw stability. The study participants were having osteoporosis, as diagnosed by measuring bone mineral density by dual energy X-ray absorptiometry (DXA), which is currently the gold standard diagnostic method for establishing the presence of osteoporosis. The authors reported significant improvement in pain as per the visual analog scale (VAS) and the quality of life assessed by the Oswestry Disability Index (ODI). None of the patients had signs of nonunion, screw pullout or hardware failure, or adjacent vertebral body fractures.[7]

Though osteoporosis is commonly diagnosed and treated by endocrinologists, rheumatologists, and orthopedic surgeons, the neurosurgeons are frequently exposed to the entity because of the common co-occurrence of thecal compression in clinical practice. Hence, it is essential to understand the basic diagnostic and therapeutic modalities in osteoporosis.

Osteoporosis is defined by the World Health Organisation (1993) as a “disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk.” It is currently diagnosed noninvasively by measuring bone mass as bone mineral content per square centimeter [bone mineral density (BMD) expressed as g/cm 2] at the lumbar spine (L1-L4) and hip (total hip and femoral neck). BMD determines 70% of bone strength, and hence, currently DXA is the gold standard method available to the clinicians.[8] The microarchitecture of trabecular and cortical bone is studied in the research setting by carrying out high-resolution peripheral quantitative computed tomography (HRpQCT), an investigation that is is not yet available to the clinicians. The BMD measurements are transformed into a T-score, which reflects the number of standard deviations (SD) above or below the mean in healthy young adults. The diagnostic criteria of osteoporosis are given in [Table 1].
Table 1: WHO osteoporosis diagnostic classification

Click here to view


Osteoporosis can be age related or can be due to several other medical disorders or lifestyle-related issues. Some of these disorders are not clinically apparent and can be life threatening if not diagnosed and treated appropriately. Hence, it is of paramount importance to diagnose the etiology of osteoporosis by different investigations,[8] and a consultation with the endocrinologists is mandatory before planning any surgical procedure on the spine.

Treatment of osteoporosis is either by administrating anabolic (teriparatide) or antiresorptive drugs (bisphosphonates, denosumab, hormone replacement therapy, calcitonin, etc.). The efficacy of these drugs is evaluated based on the reduction in the incidence of future fractures, either clinical or radiological, over a period of time. Because patients with osteoporosis are more prone to developing fractures, anabolic therapy is preferred; whereas in patients with osteopenia, oral antiresorptive drugs (alendronate, risedronate, ibandronate) are justified.[9] Teriparatide is usually given subcutaneously for 18–24 months whereas bisphosphonate is given at least for 5 years, and thereafter, continuation is decided by the change in the BMD recordings and the presence of other risk factors for fractures. Zoledronic acid, a bisphosphonate, is given intravenously every year and is almost equally effective as teriparatide; however, there is risk of development of osteonecrosis of the jaw and atypical subtrochantric fracture. All these drugs improve BMD and the microarchitecture of cortical and trabecular bone.[9]

The questions that often arise include whether treatment with these drugs will strengthen the bone adequately for the fixation process to progress; and, for how long should the treatment be administered before the surgeon can perform the surgery confidently. Animal studies show that teriparatide increases postoperative rates of fusion whereas bisphosphonates decreases it.[4] There are now a few published studies related to the use of antiosteoporotic drugs in humans.

Nagahama et al., in 2011, in the first randomized controlled trial in humans, compared alendronate (35 mg p.o. every week) with vitamin D control group (alphacalcidol 1 μg/day) in osteoporotic elderly patients undergoing spinal surgery for degenerative spondylolisthesis, isthmic spondylolisthesis, or foraminal stenosis. Pedicle screw fixation and carbon polyetheretherketone cages were used in all the patients. The fusion status was radiographically assessed by functional radiography and computed tomographic (CT) scans obtained at various time intervals for 1 year. Patients in the alendronate group had a significantly higher fusion rate (95%) than that seen in the vitamin D control group (65%, P = 0.005). Significantly higher proportion of patients developed vertebral compression fractures (VCF) in the vitamin D control group (24%) compared to the alendronate group (0%). Serum marker of bone resorption [serum and urinary collagen type 1 cross-linked N-telopeptide (NTX)] were suppressed below the preoperative baseline values throughout the study period in the alendronate group; and, whereas they were initially suppressed to 16–38% at one month, they returned to the preoperative baseline values at 6 months and thereafter. This study recommends the use of alendronate in osteoporotic elderly patients undergoing spinal surgery for achieving a better fusion rate and for lowering the incidence of vertebral compression fractures (VCFs).[10]

Ohtori et al., in 2012, compared teriparatide (20ug s/c daily) with bisphosphonates (risedronate 17.5 mg p.o. weekly) in 57 postmenopausal women with osteoporosis with degenerative spondylolisthesis.[11] Teriparatide and risedronate (bisphosphonates) were administered for 2 months before and for 8 months after surgery. All patients underwent decompression and 1- and 2-level instrumented posterolateral fusion with local bone graft. Fusion rate, duration of bony union, and pain scores were evaluated 1 year after the surgery. The teriparatide group, as compared to the risedronate group, had significantly shorter mean period of bone union, as evaluated by radiographic imaging (teriparatide group 8.5 ± 2.0 months vs risedronate group 9.9 ± 2.0, P = 0.04) and by CT imaging (teriparatide group 8.0 ± 2.5 months vs risedronate group 9.7 ± 2.0, P = 0.03). The proportion of patients achieving bony union at 12 months of follow-up was significantly higher with teriparatide (84% with radiographic imaging and 82% with CT evaluation) compared with that of risedronate (74% with radiological evaluation and 68% with CT evaluation). Facetal fusion was observed in a higher proportion of patients receiving teriparatide (79%) as compared to risedronate (65%). Similarly, the rate of bone fusion in the teriparatide group was significantly higher (84%) than in the risedronate group. However, the pain score, as assessed by VAS and ODI, was not significantly different between the 2 groups at baseline and at 12 months of follow up. Importantly, there was no adverse event during the trial period. In summary, teriparatide accelerated the fusion rate and shortened the duration required for fusion to occur after instrumented lumbar posterolateral fusion in postmenopausal women with osteoporosis.

Ohtori et al., in 2013,[12] reported, in an another randomized control trial, a significantly lower incidence of pedicle screw loosening in osteoporotic patients receiving teriparatide (7–13%) as compared to bisphosphonate (risedronate 2.5 mg daily) (13–26%) and the control group (15–25%) at the end of one year of follow up.[12] Cho et al., in 2015, compared teriparatide (20 µg daily, s.c.) for 3 months followed by alendronate (91.37 mg weekly), with continuous alendronate for 1 year in osteoporotic patients undergoing posterior lumbar interbody fusion.[13] The teriparatide group showed an earlier fusion (6.0 ± 4.8 months) than the alendronate alone group (10.4 ± 7.2 months). Further, fusion rate in the teriparatide group compared to the alendronate alone group was significantly higher at 6 months (teriparatide group 77.8% vs alendronate group 53.6%). However, there was no significant difference between the two groups at 12 months. Importantly, BMD T-score was not significantly different between the two groups at 12 months. All of these studies advocate teriparatide as the preferred choice of antiosteoporotic treatment as compared to bisphosphonate.

The next question is how long should one use teriparatide before going for surgery. This question has not been addressed clearly in the literature. The retrospective analysis of a group of patients undergoing instrumented posterolateral fusion with local bone graft, as reported by Ohtori et al., in 2015, suggests the use of teriparatide for 3 months before surgery and thereafter for 10–12 months.[14] However, teriparatide is usually administered for 18–24 months in any patient with osteoporosis, and hence, can be continued for 18–24 months for prevention of future vertebral and appendicular fractures.

There are currently two major ongoing studies in spinal surgery and osteoporosis; One of them is “Analysis of hypovitaminosis D and osteopenia/osteoporosis in spinal disease patients who underwent a spinal fusion at Illinois Neurological Institute, Peoria, IL., a retrospective review from November 1, 2012 to October 31, 2014 and a prospective pilot study from July 1, 2015-June 30, 2016” (ClinicalTrials.gov Identifier: NCT02534714, https://clinicaltrials.gov/ct2/show/NCT02534714). The second study is “Use of forteo (teriparatide) in posterolateral lumbar spine fusion” (clinical trials.gov identifier: NCT01292252, https://clinicaltrials.gov/ct2/show/NCT01292252).

In the first study, the retrospective part of the study concerns assessing the preoperative (within one month of surgery) serum (25 hydroxy vitamin D) 25(OH)D levels in patients (aged above 50 years) undergoing spinal surgery for degenerative spine diseases; whereas the prospective part is estimating serum 25(OH)D levels at the preoperative stage and at 3, 6, and 12 months postoperatively, and also the preoperative BMD (DXA) within 2 years of surgery. This study is likely to be completed by July, 2018. The second study is a single-site, 2-year prospective randomized interventional double-blind placebo-controlled study to examine the effects of perioperative teriparatide treatment (12 weeks) in older adults (aged 60–90 years) undergoing multilevel posterolateral lumbar spine fusion. This study assesses the time taken for spine fusion evaluated at 6 weeks, 3 months, 6 months, and 1 year after surgery, quality of spine fusion at 1 year, self-reported pain VAS, European Quality of Life-5 Dimensions (EQ-5D), and ODI scores at the preoperative and postoperative follow-up visits. This trial is likely to be completed by December, 2016.

It is now strongly recommended that a clinical practice be adopted to screen all elderly patients to rule out osteoporosis by DXA before planning spinal surgery. This is all the more important in Indian patients as osteoporosis occurs a decade earlier than in Caucasians and they have a higher prevalence of vertebral fractures at an earlier age.[1] DXA is the gold standard investigation for the measurement of BMD; however, when DXA is not available, osteoporosis self-assessment tool (OSTA) can be used for predicting osteoporosis.[15] In addition, vitamin D deficiency is highly prevalent in Indian elderly patients [1] and can compromise the surgical outcome. Judicious use of teriparatide is required to improve the surgical outcome and prevent future vertebral and appendicular fractures.

 
  References Top

1.
Bhat KA, Kakaji M, Awasthi A, Shukla M, Dubey M, Srivastava R, et al. High prevalence of osteoporosis and morphometric vertebral fractures in Indian males aged 60 years and above: Should age for screening be lowered? J Clin Densitom 2016; pii: S1094-6950(16) 30242-6.  Back to cited text no. 1
    
2.
Marwaha RK, Tandon N, Garg MK, Kanwar R, Narang A, Sastry A, et al. Bone health in healthy Indian population aged 50 years and above. Osteoporos Int 2011;22:2829-36.  Back to cited text no. 2
    
3.
Marwaha RK, Tandon N, Gupta Y, Bhadra K, Narang A, Mani K, et al. The prevalence of and risk factors for radiographic vertebral fractures in older Indian women and men: Delhi Vertebral Osteoporosis Study (DeVOS). Arch Osteoporos 2012;7:201-7.  Back to cited text no. 3
    
4.
Shea TM, Laun J, Gonzalez-Blohm SA, Doulgeris JJ, Lee WE 3rd, Aghayev K, Vrionis FD. Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: Current status. Biomed Res Int 2014;2014:748393.  Back to cited text no. 4
    
5.
Goldstein CL, Brodke DS, Choma TJ. Surgical management of spinal conditions in the elderly osteoporotic spine. Neurosurgery 2015;77(Suppl 4):S98-107.  Back to cited text no. 5
    
6.
Shea TM, Laun J, Gonzalez-Blohm SA, Doulgeris JJ, Lee WE 3rd, Aghayev K, et al. Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: Current status. Biomed Res Int 2014;2014:748393.  Back to cited text no. 6
    
7.
Chandra VVR, Prasad BCM, Jagadeesh MA, Jayachandar V, Sanjeev A. Kumar SA, Kumar R Segmental polymethylmethacrylate-augmented fenestrated pedicle screw fixation for lumbar spondylolisthesis in patients with osteoporosis–A case series and review of literature. Neurol India 2016;65:89-95.  Back to cited text no. 7
    
8.
Camacho PM, Petak SM, Binkley N, Clarke BL, Harris ST, Hurley DL, et al. American Association Of Clinical Endocrinologists and American College Of Endocrinology clinical practice guidelines for the diagnosis and treatment of postmenopausal osteoporosis - 2016. Endocr Pract 2016;22(Suppl 4):1-42.  Back to cited text no. 8
    
9.
Kanis JA, McCloskey EV, Johansson H, Cooper C, Rizzoli R, Reginster JY; Scientific Advisory Board of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF). European guidance for the diagnosis and management of osteoporosis in postmenopausal women. Osteoporos Int 2013;24:23-57.  Back to cited text no. 9
    
10.
Nagahama K, Kanayama M, Togawa D, Hashimoto T, Minami A. Does alendronate disturb the healing process of posterior lumbar interbody fusion? A prospective randomized trial. J Neurosurg Spine 2011;14:500-7.  Back to cited text no. 10
    
11.
Ohtori S, Inoue G, Orita S, Yamauchi K, Eguchi Y, Ochiai N, et al. Teriparatide accelerates lumbar posterolateral fusion in women with postmenopausal osteoporosis: Prospective study. Spine (Phila Pa 1976) 2012;37:E1464-8.  Back to cited text no. 11
    
12.
Ohtori S, Inoue G, Orita S, Yamauchi K, Eguchi Y, Ochiai N, et al. Comparison of teriparatide and bisphosphonate treatment to reduce pedicle screw loosening after lumbar spinal fusion surgery in postmenopausal women with osteoporosis from a bone quality perspective. Spine 2013;38:E487-92.  Back to cited text no. 12
    
13.
Cho PG, Ji GY, Shin DA, Ha Y, Yoon DH, Kim KN. An effect comparison of teriparatide and bisphosphonate on posterior lumbar interbody fusion in patients with osteoporosis: A prospective cohort study and preliminary data. Eur Spine J 2015.  Back to cited text no. 13
    
14.
Ohtori S, Orita S, Yamauchi K, Eguchi Y, Ochiai N, Kuniyoshi K, et al. More than 6 months of teriparatide treatment was more effective for bone union than shorter treatment following lumbar posterolateral fusion surgery. Asian Spine J 2015;9:573-80.  Back to cited text no. 14
    
15.
Bhat KA, Kakaji M, Awasthi A, Kumar K, Mishra K, Shukla M, et al. Utility of osteoporosis self-assessment tool as a screening tool for predicting osteoporosis in Indian men. J Clin Densitom 2016.  Back to cited text no. 15
    



 
 
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