- Email: [email protected]
Salvage Percutaneous Vertebral Augmentation Using Polymethyl Methacrylate in Patients with Failed Interbody Fusion
Case Report
Salvage Percutaneous Vertebral Augmentation Using Polymethyl Methacrylate in Patients with Failed Interbody Fusion Dong-Ju Yun1, Byeong-Wook Hwang1, Hyeong-Seok Oh1, Jin-Sung Kim3, Sang-Hyeop Jeon2, Sang-Ho Lee4
Key words Failed interbody fusion - Polymethyl methacrylate - Salvage augmentation - Vertebroplasty -
Abbreviations and Acronyms ALIF: Anterior lumbar interbody fusion PMMA: Polymethyl methacrylate From the Departments of 1Neurosurgery and 2Cardiothoracic Surgery, Spine Health Wooridul Hospital, Busan; 3 Department of Neurosurgery, Seoul St. Mary’s Hospital, Seoul; and 4Department of Neurosurgery, Spine Health Wooridul Hospital Gangnam, Seoul, Korea To whom correspondence should be addressed: Byeong-Wook Hwang M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2016). http://dx.doi.org/10.1016/j.wneu.2016.08.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
- BACKGROUND:
Percutaneous vertebral augmentation with cement is used as a salvage procedure for failed instrumentation. Few studies have reported the use of this procedure for failed anterior lumbar fusion in elderly patients with osteoporosis and other complicated diseases who have undergone a previous major operation.
- METHODS:
Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the implant after an initial operation were examined. After the development of implant failure, the patients underwent vertebral augmentation with polymethyl methacrylate.
- RESULTS:
Mean patient age was 73.4 years (range, 67e78 years), and mean bone mineral density was L2.96 (range, L2.1 to L3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3e38 months). Although the subjective clinical outcome was not satisfying to the patients, no loss of correction, fractures, or screw loosening occurred during the follow-up period.
- CONCLUSIONS:
The injection of cement around the instrument might help to stabilize it by providing strength to the axis and preventing further loosening. This salvage procedure could be an alternative in the management of cases with failed interbody fusion.
INTRODUCTION In patients with severe osteoporosis, instrumented lumbar interbody fusion may result in fixation failure or nonunion because of the increased risk of interbody graft subsidence or decreased pedicle screw pullout strength.1-7 These complications can subsequently require additional surgery. Among the various methods used to overcome these problems, preventive polymethyl methacrylate (PMMA) cement augmentation has yielded favorable results with both anterior and posterior approaches.8-13 However, few previous studies have reported on salvage vertebral augmentation for failed anterior interbody fusion in elderly patients who have osteoporosis and other complicated conditions (e.g., Parkinson disease) and have undergone a previous major operation. A clinical evaluation of salvage vertebral augmentation with PMMA in patients with failed anterior interbody fusions was performed to determine the performance and safety of this technique.
MATERIALS AND METHODS Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the instruments after the initial operation were evaluated. During the initial operation, 5 patients received lumbar corpectomy via an anterior approach, and 3 patients underwent anterior lumbar interbody fusion (ALIF) with posterior fixation. After the development of implant failure, all patients underwent PMMA augmentation as a salvage procedure via an anterior or posterior approach. RESULTS The characteristics and clinical outcomes of the 8 patients are summarized in Table 1. The mean age of patients was 73.4 years (range, 67e78 years), and the mean bone mineral density was 2.96
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(range, 2.1 to 3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3e38 months), and the mean clinical follow-up phone call period was 36.25 months (range, 13e71 months). Of the patients, 5 previously underwent corpectomy, and 3 underwent ALIF (Table 1). After the development of implant failure, all patients experienced lower back pain. All patients experienced symptom relief in the short-term period after PMMA augmentation (Figure 1). However, the clinical results during the long-term period were unsatisfactory from the perspective of the patients. In phone call investigations of the clinical outcome, 6 patients refused to receive free radiologic follow-up because of unsatisfactory clinical results. During a recent follow-up, no additional operations had been performed in the 8 patients in the study.
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CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Table 1. Patient Characteristics and Clinical Outcomes FU Period (months)/Last Phone FU Period Pre-OP VAS Post-OP VAS Phone VAS Pre-OP Post-OP Phone (months) (Back/Leg) (Back/Leg) Back/Leg) ODI (%) ODI (%) ODI (%) BMD
Age Patient (years)/Sex
Initial Operation
1
68/F
ALIF L3-L4, L4-L5, L5-S1
10/13
8/8
3/3
3/3
78.54
12.32
13.57
2.5
2
77/M
L3 corpectomy
3/17
9/7
5/2
8/7
75.56
26.67
71.11
2.7
Comment
3
73/M
L3 corpectomy
3/19
7
2/2
2/1
50.2
18.1
17.78
3.1
4
77/F
L3, L4 corpectomy
18/32
7/6
3/7
9/8
80
60
62.22
3.8
Cage change
5
72/F
L3 corpectomy, ALIF L4-L5, L5-S1
28/41
7/6
2/1
7/6
47.3
40
80
2.5
6
75/M
ALIF L2-L3, L3-L4, L4-L5
24/37
8/9
5/7
8/9
76
62.2
82.22
2.1
Cement leakage
7
78/M
L4 corpectomy
38/60
8/8
3/2
2/2
82.2
64.8
40
3.6
Cage change, fusion extension
8
67/M
ALIF L5-L6
5/71
0/10
5/7
8/8
70
51.11
62.22
3.4 Cement leakage, infection, screw removal
FU, follow-up; OP, operative; VAS, visual analog scale (score); ODI, Oswestry Disability Index (score); BMD, bone mineral density; F, female; ALIF, anterior lumbar interbody fusion; M, male.
ILLUSTRATIVE CASES Case 1 A 68-year-old woman with osteoporosis initially underwent ALIF at L3-L4, L4-L5, and L5-S1 and posterior fusion. However, 2 weeks later, an L3 anterior body fracture, L3 right pedicle fracture, L3 pedicle screw loosening and displacement, and L3-L4
interbody cage subsidence occurred. She underwent vertebroplasty at the L3 level. The needle for vertebroplasty was inserted in a cranial-to-caudal direction through another trajectory because the vertebral body fracture was at the anteroinferior portion of the L3 vertebrae (Figure 2). Before the vertebroplasty, the operating table was modulated to create lumbar
Figure 1. Follow-up results regarding clinical outcome of Oswestry Disability Index score in all patients. OP, operative.
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lordosis. When the operating table was extended, the displaced screw at L3 was located inside the vertebral body. Maintaining this position, cement augmentation was performed. The patient’s symptoms were improved immediately. There was no instrument failure and no new symptoms for 1 year postoperatively (Figure 3). Case 2 A 73-year-old man had experienced lower back pain, stooping, and leg pain. In 2010, while in Russia, he underwent posterior decompression and subsequently sustained a fall, for which he underwent an L3 vertebroplasty and posterior fusion. Screw loosening was identified 1 month later. When he visited our institute, he had cerebral palsy and osteoporosis as well as a pacemaker. In August 2011, an L3 corpectomy using a mesh cage and a posterior fixation from the L1 to L5 levels were performed. Cage subsidence was observed 1 week later, and the cage was replaced with a larger one. The cage subsidence recurred 1 week later (Figure 4). The attending surgeon decided to change the cage to an expandable type and to perform a rod extension from T12
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2016.08.036
CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 2. Illustrative case 1. (A and B) Immediate postoperative film after 3-level anterior lumbar interbody fusion. (C) Occurrence of screw loosening
to S1 using an iliac screw. However, 2 days later, progression of the cage subsidence was identified. The decision was made to perform PMMA augmentation with a bilateral extrapedicular approach. The postoperative course was uneventful, and the patient was subsequently discharged. Radiology at a 3-month follow-up examination showed no recurrence of the cage subsidence, although an erosive change was detected at the upper endplate (Figure 5). Case 3 A 77-year-old woman with Parkinson disease and osteoporosis initially underwent vertebroplasty at the L4 level and posterior decompression for lumbar stenosis. After 7 months, she was experiencing bilateral buttock and leg pain. Claudication recurred and was sustained owing to an L3 compression fracture. An L3 and L4 lumbar corpectomy and posterolateral fusion from L1 to L5 were performed. However, 2 months later, we identified bilateral screw loosening at L5 (Figure 6). She underwent transpedicular cement augmentation
(arrow). (D) Vertebral body fracture at L3 (dotted arrow), and subsidence at L3-L4 level (arrowhead) 1 week later.
through another trajectory for salvage purposes. Her symptoms subsequently improved. Follow-up radiologic imaging revealed consistent cement distribution around the construct, no further collapse of the vertebra, and no new lucencies surrounding the construct. However, incomplete bone fusion between the endplate and implant was observed (Figure 7). Case 4 A 78-year-old man who previously underwent posterior decompression and interspinous device insertion sustained a burst fracture at L4. He underwent an L4 corpectomy. Cage subsidence was identified 1 week later (Figure 8). Replacement of the mesh cage with 2 new mesh cages and salvage cement augmentation were done in the periscrew area and the upper and lower endplates. Despite augmentation, 4 months later, the pseudarthrosis of the screw fixation was aggravated. Fusion extension to the upper and lower levels was performed (Figure 9).
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DISCUSSION Spinal fusion is usually performed to reinforce the spine in patients with spinal instability. However, when pain relief is not achieved because of pseudarthrosis, a revision surgery is needed. This second surgery can lead to a more complicated condition, prolonged hospitalization, and unexpected costs and may fail to provide further pain relief. Vertebral body augmentation procedures such as vertebroplasty have been used extensively over the past decade for osteoporotic fractures. Although the literature regarding the treatment of fractures in the thoracolumbar region is extensive,14-16 very few data are available on the special problem of cage subsidence in osteoporotic bones or other complicated conditions.17,18 In the present study, we introduced vertebroplasty as an alternative option to augmentation with pedicle screws. Because the pullout strength of the screw pitch is decreased by the decreased quality and quantity of cancellous bone, fixation loosening is likely to
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CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 3. Illustrative case 1. (A and B) Salvage vertebroplasty at L3 was performed through an extrapedicular approach. (C and D) Immediate
occur in patients with osteoporosis.6,8-10,19,20 PMMA augmentation increases the screw pullout strength. PMMA
postoperative film after vertebroplasty. (E) Postoperative film 10 months later.
augments the vertebral body strength and prevents subsidence of the bone grafts. Attempting to fill the vertebral bodies with
PMMA to the levels of interface with the grafts allows for decreased destruction of an already poor bony substrate.21
Figure 4. Illustrative case 2. (A and B) Preoperative film. (C and D) Immediate postoperative film. (E and F) Cage subsidence (arrow) occurred 1 week later.
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CASE REPORT DONG-JU YUN ET AL.
Figure 5. Illustrative case 2. (A and B) The cage was replaced with an expandable cage. Pre- (C) View before augmentation. (D) View after
Figure 6. Illustrative case 3. (A and B) Film before lumbar corpectomy at L3 and L4. (C and D) Film after corpectomy at L3 and L4 and posterolateral
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SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
augmentation. (E) Intraoperative view. (F and G) Last follow-up film.
fusion from L1 to L5. Screw pseudarthrosis (arrows) (E) and cage subsidence (dotted arrow) (F) were observed 2 months later.
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CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 7. Illustrative case 3. (A and B) Salvage vertebroplasty at L5 through an extrapedicular approach. (CeF) Postoperative film 18 months later.
To prevent cage subsidence, Kim et al.12 injected PMMA anteriorly into the center of the vertebral body before cage insertion. In their study, solid fusion was achieved in all patients with
instrumented ALIF alone and in combination with anterior PMMA augmentation; none of the patients experienced nonunion. In our cases, anterior cement augmentation itself did
Figure 8. Illustrative case 4. (A and B) There was a burst fracture preoperatively. (C and D) Corpectomy was performed at L4, and posterior
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not increase the nonunion rate in instrumented ALIF. In the case of osteoporotic patients who have undergone anterior reconstructed interbody fusion, the anterior substitutes
fusion was performed at L3 and L5. (E) Cage subsidence occurred 2 weeks later (arrows).
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2016.08.036
CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 9. Illustrative case 4. (A and B) Replacement of mesh cage with 2 new mesh cages and polymethyl methacrylate augmentation at L3 and L5 were performed through an anterior approach. (C) Pseudarthrosis of the
can subside, infiltrate into the endplate, and consequently weaken it, making it more prone to fractures. The fractures are painful and debilitating for the patient and can result in the patient becoming immobile and dependent. Furthermore, in the case of elderly patients with comorbid conditions, additional operations via the anterior approach can be fatal. In the present study, 6 patients underwent percutaneous vertebral augmentation with PMMA as a salvage procedure under Carm control. The augmentation procedure was simple and performed as a local procedure. The vertebroplasty needle was inserted in the extrapedicular area adjacent to the previously inserted pedicle screw and then advanced inside the pedicle (Figures 3 and 7). In 2 cases, the PMMA augmentation was performed anteriorly, under general anesthesia, because the cage had to be changed via an anterior approach. The operating table was modified to realign dislodged instruments to their original position under C-arm control. This modification might give strength to the failed instruments. Cement leakage occurred in 1 case and resulted in infection. In another case,
screw fixation occurred (arrows) 4 months later. (D and E) Fusion extension to the upper and lower levels was performed.
fusion extension was required because of cage subsidence despite vertebroplasty augmentation. However, 6 cases showed good radiologic results immediately as well as at follow-up at least 1 year later. Based on our findings, we believe an unstable, fractured vertebra body might be stabilized by augmentation. Immediately postoperatively, the visual analog scale score in all patients revealed a significant reduction in pain compared with before the operation. At the shortterm follow-up examination, we observed a significant reduction in the Oswestry Disability Index score. However, the Oswestry Disability Index score and visual analog scale score were unsatisfactory in most cases at the time of final follow-up examination. In osteoporotic patients who have undergone revisional surgery, this situation can lead to a more complicated condition, prolonged hospitalization, and unexpected costs as well as the possibility of failing to provide further pain relief. Furthermore, revisional surgery affects patients’ psychosocial mood, which might lead to failure of spinal surgery. These factors might contribute to the unsatisfactory clinical outcome.
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Introducing bone cement close to the endplates might theoretically compromise osteogenesis because the PMMA cement can be toxic to bone.22 Although the cement was covered, possible vascularization and osteogenesis from the other endplate and the surrounding soft tissue can continue.23 In the present study, we did not observe any necrosis of the vertebrae after cement augmentation during the follow-up period. Buttressing the spinal construct with PMMA cement offers a minimally invasive solution for failed spinal constructs. The PMMA augmentation for failed instrumentation might be able to stabilize the loose construct and strengthen weakened bone. However, the clinical outcome was generally unsatisfactory, and the number of cases in this study was too small. CONCLUSIONS The salvage procedure with cement augmentation described in this study could be an alternative in the management of cases with failed interbody fusion. This procedure may be an unavoidable choice if patients have risk factors (e.g., old age, osteoporosis, or previous major surgery)
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CASE REPORT DONG-JU YUN ET AL.
for complications. In particular, the cement surrounding the construct may provide strength to the axis and prevent further loosening. However, clinical analysis with long-term follow-up is needed. REFERENCES 1. Jost B, Cripton PA, Lund T, Oxland TR, Lippuner K, Jaeger P, et al. Compressive strength of interbody cages in the lumbar spine: the effect of cage shape, posterior instrumentation and bone density. Eur Spine J. 1998;7:132-141. 2. Kodihalli S, Sivanandan V, Nagaraja KV, Shaw D, Halvorson DA. A type-specific avian influenza virus subunit vaccine for turkeys: induction of protective immunity to challenge infection. Vaccine. 1994;12:1467-1472. 3. Lund T, Oxland TR, Jost B, Cripton P, Grassmann S, Etter C, et al. Interbody cage stabilisation in the lumbar spine: biomechanical evaluation of cage design, posterior instrumentation and bone density. J Bone Joint Surg Br. 1998;80: 351-359. 4. McLain RF, McKinley TO, Yerby SA, Smith TS, Sarigul-Klijn N. The effect of bone quality on pedicle screw loading in axial instability. A synthetic model. Spine (Phila Pa 1976). 1997;22: 1454-1460. 5. Oxland TR, Lund T, Jost B, Cripton P, Lippuner K, Jaeger P, et al. The relative importance of vertebral bone density and disc degeneration in spinal flexibility and interbody implant performance. An in vitro study. Spine (Phila Pa 1976). 1996;21: 2558-2569. 6. Soshi S, Shiba R, Kondo H, Murota K. An experimental study on transpedicular screw fixation in relation to osteoporosis of the lumbar spine. Spine (Phila Pa 1976). 1991;16:1335-1341. 7. Tsantrizos A, Baramki HG, Zeidman S, Steffen T. Segmental stability and compressive strength of posterior lumbar interbody fusion implants. Spine (Phila Pa 1976). 2000;25:1899-1907.
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SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
8. Burval DJ, McLain RF, Milks R, Inceoglu S. Primary pedicle screw augmentation in osteoporotic lumbar vertebrae: biomechanical analysis of pedicle fixation strength. Spine (Phila Pa 1976). 2007;32:1077-1083. 9. Chang MC, Liu CL, Chen TH. Polymethylmethacrylate augmentation of pedicle screw for osteoporotic spinal surgery: a novel technique. Spine (Phila Pa 1976). 2008;33:E317-324. 10. Frankel BM, D’Agostino S, Wang C. A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation. J Neurosurg Spine. 2007;7:47-53. 11. Fransen P. Increasing pedicle screw anchoring in the osteoporotic spine by cement injection through the implant. Technical note and report of three cases. J Neurosurg Spine. 2007;7:366-369. 12. Kim KH, Lee SH, Lee DY, Shim CS, Maeng DH. Anterior bone cement augmentation in anterior lumbar interbody fusion and percutaneous pedicle screw fixation in patients with osteoporosis. J Neurosurg Spine. 2010;12:525-532. 13. Tan JS, Bailey CS, Dvorak MF, Fisher CG, Cripton PA, Oxland TR. Cement augmentation of vertebral screws enhances the interface strength between interbody device and vertebral body. Spine (Phila Pa 1976). 2007;32:334-341. 14. Kim DH, Vaccaro AR. Osteoporotic compression fractures of the spine: current options and considerations for treatment. Spine J. 2006;6:479-487. 15. Knop C, Kranabetter T, Reinhold M, Blauth M. Combined posterior-anterior stabilisation of thoracolumbar injuries utilising a vertebral body replacing implant. Eur Spine J. 2009;18:949-963. 16. Lange U, Edeling S, Knop C, Bastian L, Oeser M, Krettek C, et al. Anterior vertebral body replacement with a titanium implant of adjustable height: a prospective clinical study. Eur Spine J. 2007;16: 161-172. 17. Lowe TG, Hashim S, Wilson LA, O’Brien MF, Smith DA, Diekmann MJ, et al. A biomechanical study of regional endplate strength and cage
morphology as it relates to structural interbody support. Spine (Phila Pa 1976). 2004;29:2389-2394. 18. Vieweg U, Solch O, Kalff R. Vertebral body replacement system Synex in unstable burst fractures of the thoracic and lumbar spine—a retrospective study with 30 patients [in German] Zentralbl Neurochir. 2003;64:58-64. 19. Skinner R, Maybee J, Transfeldt E, Venter R, Chalmers W. Experimental pullout testing and comparison of variables in transpedicular screw fixation. A biomechanical study. Spine (Phila Pa 1976). 1990;15:195-201. 20. Sugimoto Y, Tanaka M, Konishi H, Takigawa T, Nakanishi K, Misawa H, et al. Posterior spinal fusion using a pedicle nail system with polymethylmethacrylate in a paraplegic patient after vertebral collapse caused by osteoporosis. Spine J. 2009;9:e5-8. 21. Oppenlander ME, Bina R, Snyder LA, Dickman CA. Intravertebral polymethylmethacrylate augmentation of anterior cervical discectomy fusion and plating in the setting of osteoporosis. J Spinal Disord Tech. 2014; 27:185-188. 22. Kalteis T, Luring C, Gugler G, Zysk S, Caro W, Handel M, et al. Acute tissue toxicity of PMMA bone cements [in German] Z Orthop Ihre Grenzgeb. 2004;142:666-672. 23. Geiger F, Kafchitsas K, Rauschmann M. Anterior vertebroplasty of adjacent levels after vertebral body replacement. Eur Spine J. 2011;20:1385-1392.
Conflict of interest statement: This study was supported by a grant from the Spine Health Wooridul Hospital. Received 29 May 2016; accepted 9 August 2016 Citation: World Neurosurg. (2016). http://dx.doi.org/10.1016/j.wneu.2016.08.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2016.08.036
Salvage Percutaneous Vertebral Augmentation Using Polymethyl Methacrylate in Patients with Failed Interbody Fusion Dong-Ju Yun1, Byeong-Wook Hwang1, Hyeong-Seok Oh1, Jin-Sung Kim3, Sang-Hyeop Jeon2, Sang-Ho Lee4
Key words Failed interbody fusion - Polymethyl methacrylate - Salvage augmentation - Vertebroplasty -
Abbreviations and Acronyms ALIF: Anterior lumbar interbody fusion PMMA: Polymethyl methacrylate From the Departments of 1Neurosurgery and 2Cardiothoracic Surgery, Spine Health Wooridul Hospital, Busan; 3 Department of Neurosurgery, Seoul St. Mary’s Hospital, Seoul; and 4Department of Neurosurgery, Spine Health Wooridul Hospital Gangnam, Seoul, Korea To whom correspondence should be addressed: Byeong-Wook Hwang M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2016). http://dx.doi.org/10.1016/j.wneu.2016.08.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
- BACKGROUND:
Percutaneous vertebral augmentation with cement is used as a salvage procedure for failed instrumentation. Few studies have reported the use of this procedure for failed anterior lumbar fusion in elderly patients with osteoporosis and other complicated diseases who have undergone a previous major operation.
- METHODS:
Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the implant after an initial operation were examined. After the development of implant failure, the patients underwent vertebral augmentation with polymethyl methacrylate.
- RESULTS:
Mean patient age was 73.4 years (range, 67e78 years), and mean bone mineral density was L2.96 (range, L2.1 to L3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3e38 months). Although the subjective clinical outcome was not satisfying to the patients, no loss of correction, fractures, or screw loosening occurred during the follow-up period.
- CONCLUSIONS:
The injection of cement around the instrument might help to stabilize it by providing strength to the axis and preventing further loosening. This salvage procedure could be an alternative in the management of cases with failed interbody fusion.
INTRODUCTION In patients with severe osteoporosis, instrumented lumbar interbody fusion may result in fixation failure or nonunion because of the increased risk of interbody graft subsidence or decreased pedicle screw pullout strength.1-7 These complications can subsequently require additional surgery. Among the various methods used to overcome these problems, preventive polymethyl methacrylate (PMMA) cement augmentation has yielded favorable results with both anterior and posterior approaches.8-13 However, few previous studies have reported on salvage vertebral augmentation for failed anterior interbody fusion in elderly patients who have osteoporosis and other complicated conditions (e.g., Parkinson disease) and have undergone a previous major operation. A clinical evaluation of salvage vertebral augmentation with PMMA in patients with failed anterior interbody fusions was performed to determine the performance and safety of this technique.
MATERIALS AND METHODS Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the instruments after the initial operation were evaluated. During the initial operation, 5 patients received lumbar corpectomy via an anterior approach, and 3 patients underwent anterior lumbar interbody fusion (ALIF) with posterior fixation. After the development of implant failure, all patients underwent PMMA augmentation as a salvage procedure via an anterior or posterior approach. RESULTS The characteristics and clinical outcomes of the 8 patients are summarized in Table 1. The mean age of patients was 73.4 years (range, 67e78 years), and the mean bone mineral density was 2.96
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(range, 2.1 to 3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3e38 months), and the mean clinical follow-up phone call period was 36.25 months (range, 13e71 months). Of the patients, 5 previously underwent corpectomy, and 3 underwent ALIF (Table 1). After the development of implant failure, all patients experienced lower back pain. All patients experienced symptom relief in the short-term period after PMMA augmentation (Figure 1). However, the clinical results during the long-term period were unsatisfactory from the perspective of the patients. In phone call investigations of the clinical outcome, 6 patients refused to receive free radiologic follow-up because of unsatisfactory clinical results. During a recent follow-up, no additional operations had been performed in the 8 patients in the study.
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CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Table 1. Patient Characteristics and Clinical Outcomes FU Period (months)/Last Phone FU Period Pre-OP VAS Post-OP VAS Phone VAS Pre-OP Post-OP Phone (months) (Back/Leg) (Back/Leg) Back/Leg) ODI (%) ODI (%) ODI (%) BMD
Age Patient (years)/Sex
Initial Operation
1
68/F
ALIF L3-L4, L4-L5, L5-S1
10/13
8/8
3/3
3/3
78.54
12.32
13.57
2.5
2
77/M
L3 corpectomy
3/17
9/7
5/2
8/7
75.56
26.67
71.11
2.7
Comment
3
73/M
L3 corpectomy
3/19
7
2/2
2/1
50.2
18.1
17.78
3.1
4
77/F
L3, L4 corpectomy
18/32
7/6
3/7
9/8
80
60
62.22
3.8
Cage change
5
72/F
L3 corpectomy, ALIF L4-L5, L5-S1
28/41
7/6
2/1
7/6
47.3
40
80
2.5
6
75/M
ALIF L2-L3, L3-L4, L4-L5
24/37
8/9
5/7
8/9
76
62.2
82.22
2.1
Cement leakage
7
78/M
L4 corpectomy
38/60
8/8
3/2
2/2
82.2
64.8
40
3.6
Cage change, fusion extension
8
67/M
ALIF L5-L6
5/71
0/10
5/7
8/8
70
51.11
62.22
3.4 Cement leakage, infection, screw removal
FU, follow-up; OP, operative; VAS, visual analog scale (score); ODI, Oswestry Disability Index (score); BMD, bone mineral density; F, female; ALIF, anterior lumbar interbody fusion; M, male.
ILLUSTRATIVE CASES Case 1 A 68-year-old woman with osteoporosis initially underwent ALIF at L3-L4, L4-L5, and L5-S1 and posterior fusion. However, 2 weeks later, an L3 anterior body fracture, L3 right pedicle fracture, L3 pedicle screw loosening and displacement, and L3-L4
interbody cage subsidence occurred. She underwent vertebroplasty at the L3 level. The needle for vertebroplasty was inserted in a cranial-to-caudal direction through another trajectory because the vertebral body fracture was at the anteroinferior portion of the L3 vertebrae (Figure 2). Before the vertebroplasty, the operating table was modulated to create lumbar
Figure 1. Follow-up results regarding clinical outcome of Oswestry Disability Index score in all patients. OP, operative.
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lordosis. When the operating table was extended, the displaced screw at L3 was located inside the vertebral body. Maintaining this position, cement augmentation was performed. The patient’s symptoms were improved immediately. There was no instrument failure and no new symptoms for 1 year postoperatively (Figure 3). Case 2 A 73-year-old man had experienced lower back pain, stooping, and leg pain. In 2010, while in Russia, he underwent posterior decompression and subsequently sustained a fall, for which he underwent an L3 vertebroplasty and posterior fusion. Screw loosening was identified 1 month later. When he visited our institute, he had cerebral palsy and osteoporosis as well as a pacemaker. In August 2011, an L3 corpectomy using a mesh cage and a posterior fixation from the L1 to L5 levels were performed. Cage subsidence was observed 1 week later, and the cage was replaced with a larger one. The cage subsidence recurred 1 week later (Figure 4). The attending surgeon decided to change the cage to an expandable type and to perform a rod extension from T12
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SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 2. Illustrative case 1. (A and B) Immediate postoperative film after 3-level anterior lumbar interbody fusion. (C) Occurrence of screw loosening
to S1 using an iliac screw. However, 2 days later, progression of the cage subsidence was identified. The decision was made to perform PMMA augmentation with a bilateral extrapedicular approach. The postoperative course was uneventful, and the patient was subsequently discharged. Radiology at a 3-month follow-up examination showed no recurrence of the cage subsidence, although an erosive change was detected at the upper endplate (Figure 5). Case 3 A 77-year-old woman with Parkinson disease and osteoporosis initially underwent vertebroplasty at the L4 level and posterior decompression for lumbar stenosis. After 7 months, she was experiencing bilateral buttock and leg pain. Claudication recurred and was sustained owing to an L3 compression fracture. An L3 and L4 lumbar corpectomy and posterolateral fusion from L1 to L5 were performed. However, 2 months later, we identified bilateral screw loosening at L5 (Figure 6). She underwent transpedicular cement augmentation
(arrow). (D) Vertebral body fracture at L3 (dotted arrow), and subsidence at L3-L4 level (arrowhead) 1 week later.
through another trajectory for salvage purposes. Her symptoms subsequently improved. Follow-up radiologic imaging revealed consistent cement distribution around the construct, no further collapse of the vertebra, and no new lucencies surrounding the construct. However, incomplete bone fusion between the endplate and implant was observed (Figure 7). Case 4 A 78-year-old man who previously underwent posterior decompression and interspinous device insertion sustained a burst fracture at L4. He underwent an L4 corpectomy. Cage subsidence was identified 1 week later (Figure 8). Replacement of the mesh cage with 2 new mesh cages and salvage cement augmentation were done in the periscrew area and the upper and lower endplates. Despite augmentation, 4 months later, the pseudarthrosis of the screw fixation was aggravated. Fusion extension to the upper and lower levels was performed (Figure 9).
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DISCUSSION Spinal fusion is usually performed to reinforce the spine in patients with spinal instability. However, when pain relief is not achieved because of pseudarthrosis, a revision surgery is needed. This second surgery can lead to a more complicated condition, prolonged hospitalization, and unexpected costs and may fail to provide further pain relief. Vertebral body augmentation procedures such as vertebroplasty have been used extensively over the past decade for osteoporotic fractures. Although the literature regarding the treatment of fractures in the thoracolumbar region is extensive,14-16 very few data are available on the special problem of cage subsidence in osteoporotic bones or other complicated conditions.17,18 In the present study, we introduced vertebroplasty as an alternative option to augmentation with pedicle screws. Because the pullout strength of the screw pitch is decreased by the decreased quality and quantity of cancellous bone, fixation loosening is likely to
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SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 3. Illustrative case 1. (A and B) Salvage vertebroplasty at L3 was performed through an extrapedicular approach. (C and D) Immediate
occur in patients with osteoporosis.6,8-10,19,20 PMMA augmentation increases the screw pullout strength. PMMA
postoperative film after vertebroplasty. (E) Postoperative film 10 months later.
augments the vertebral body strength and prevents subsidence of the bone grafts. Attempting to fill the vertebral bodies with
PMMA to the levels of interface with the grafts allows for decreased destruction of an already poor bony substrate.21
Figure 4. Illustrative case 2. (A and B) Preoperative film. (C and D) Immediate postoperative film. (E and F) Cage subsidence (arrow) occurred 1 week later.
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Figure 5. Illustrative case 2. (A and B) The cage was replaced with an expandable cage. Pre- (C) View before augmentation. (D) View after
Figure 6. Illustrative case 3. (A and B) Film before lumbar corpectomy at L3 and L4. (C and D) Film after corpectomy at L3 and L4 and posterolateral
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augmentation. (E) Intraoperative view. (F and G) Last follow-up film.
fusion from L1 to L5. Screw pseudarthrosis (arrows) (E) and cage subsidence (dotted arrow) (F) were observed 2 months later.
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SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 7. Illustrative case 3. (A and B) Salvage vertebroplasty at L5 through an extrapedicular approach. (CeF) Postoperative film 18 months later.
To prevent cage subsidence, Kim et al.12 injected PMMA anteriorly into the center of the vertebral body before cage insertion. In their study, solid fusion was achieved in all patients with
instrumented ALIF alone and in combination with anterior PMMA augmentation; none of the patients experienced nonunion. In our cases, anterior cement augmentation itself did
Figure 8. Illustrative case 4. (A and B) There was a burst fracture preoperatively. (C and D) Corpectomy was performed at L4, and posterior
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not increase the nonunion rate in instrumented ALIF. In the case of osteoporotic patients who have undergone anterior reconstructed interbody fusion, the anterior substitutes
fusion was performed at L3 and L5. (E) Cage subsidence occurred 2 weeks later (arrows).
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2016.08.036
CASE REPORT DONG-JU YUN ET AL.
SALVAGE PERCUTANEOUS VERTEBRAL AUGMENTATION USING PMMA
Figure 9. Illustrative case 4. (A and B) Replacement of mesh cage with 2 new mesh cages and polymethyl methacrylate augmentation at L3 and L5 were performed through an anterior approach. (C) Pseudarthrosis of the
can subside, infiltrate into the endplate, and consequently weaken it, making it more prone to fractures. The fractures are painful and debilitating for the patient and can result in the patient becoming immobile and dependent. Furthermore, in the case of elderly patients with comorbid conditions, additional operations via the anterior approach can be fatal. In the present study, 6 patients underwent percutaneous vertebral augmentation with PMMA as a salvage procedure under Carm control. The augmentation procedure was simple and performed as a local procedure. The vertebroplasty needle was inserted in the extrapedicular area adjacent to the previously inserted pedicle screw and then advanced inside the pedicle (Figures 3 and 7). In 2 cases, the PMMA augmentation was performed anteriorly, under general anesthesia, because the cage had to be changed via an anterior approach. The operating table was modified to realign dislodged instruments to their original position under C-arm control. This modification might give strength to the failed instruments. Cement leakage occurred in 1 case and resulted in infection. In another case,
screw fixation occurred (arrows) 4 months later. (D and E) Fusion extension to the upper and lower levels was performed.
fusion extension was required because of cage subsidence despite vertebroplasty augmentation. However, 6 cases showed good radiologic results immediately as well as at follow-up at least 1 year later. Based on our findings, we believe an unstable, fractured vertebra body might be stabilized by augmentation. Immediately postoperatively, the visual analog scale score in all patients revealed a significant reduction in pain compared with before the operation. At the shortterm follow-up examination, we observed a significant reduction in the Oswestry Disability Index score. However, the Oswestry Disability Index score and visual analog scale score were unsatisfactory in most cases at the time of final follow-up examination. In osteoporotic patients who have undergone revisional surgery, this situation can lead to a more complicated condition, prolonged hospitalization, and unexpected costs as well as the possibility of failing to provide further pain relief. Furthermore, revisional surgery affects patients’ psychosocial mood, which might lead to failure of spinal surgery. These factors might contribute to the unsatisfactory clinical outcome.
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Introducing bone cement close to the endplates might theoretically compromise osteogenesis because the PMMA cement can be toxic to bone.22 Although the cement was covered, possible vascularization and osteogenesis from the other endplate and the surrounding soft tissue can continue.23 In the present study, we did not observe any necrosis of the vertebrae after cement augmentation during the follow-up period. Buttressing the spinal construct with PMMA cement offers a minimally invasive solution for failed spinal constructs. The PMMA augmentation for failed instrumentation might be able to stabilize the loose construct and strengthen weakened bone. However, the clinical outcome was generally unsatisfactory, and the number of cases in this study was too small. CONCLUSIONS The salvage procedure with cement augmentation described in this study could be an alternative in the management of cases with failed interbody fusion. This procedure may be an unavoidable choice if patients have risk factors (e.g., old age, osteoporosis, or previous major surgery)
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for complications. In particular, the cement surrounding the construct may provide strength to the axis and prevent further loosening. However, clinical analysis with long-term follow-up is needed. REFERENCES 1. Jost B, Cripton PA, Lund T, Oxland TR, Lippuner K, Jaeger P, et al. Compressive strength of interbody cages in the lumbar spine: the effect of cage shape, posterior instrumentation and bone density. Eur Spine J. 1998;7:132-141. 2. Kodihalli S, Sivanandan V, Nagaraja KV, Shaw D, Halvorson DA. A type-specific avian influenza virus subunit vaccine for turkeys: induction of protective immunity to challenge infection. Vaccine. 1994;12:1467-1472. 3. Lund T, Oxland TR, Jost B, Cripton P, Grassmann S, Etter C, et al. Interbody cage stabilisation in the lumbar spine: biomechanical evaluation of cage design, posterior instrumentation and bone density. J Bone Joint Surg Br. 1998;80: 351-359. 4. McLain RF, McKinley TO, Yerby SA, Smith TS, Sarigul-Klijn N. The effect of bone quality on pedicle screw loading in axial instability. A synthetic model. Spine (Phila Pa 1976). 1997;22: 1454-1460. 5. Oxland TR, Lund T, Jost B, Cripton P, Lippuner K, Jaeger P, et al. The relative importance of vertebral bone density and disc degeneration in spinal flexibility and interbody implant performance. An in vitro study. Spine (Phila Pa 1976). 1996;21: 2558-2569. 6. Soshi S, Shiba R, Kondo H, Murota K. An experimental study on transpedicular screw fixation in relation to osteoporosis of the lumbar spine. Spine (Phila Pa 1976). 1991;16:1335-1341. 7. Tsantrizos A, Baramki HG, Zeidman S, Steffen T. Segmental stability and compressive strength of posterior lumbar interbody fusion implants. Spine (Phila Pa 1976). 2000;25:1899-1907.
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8. Burval DJ, McLain RF, Milks R, Inceoglu S. Primary pedicle screw augmentation in osteoporotic lumbar vertebrae: biomechanical analysis of pedicle fixation strength. Spine (Phila Pa 1976). 2007;32:1077-1083. 9. Chang MC, Liu CL, Chen TH. Polymethylmethacrylate augmentation of pedicle screw for osteoporotic spinal surgery: a novel technique. Spine (Phila Pa 1976). 2008;33:E317-324. 10. Frankel BM, D’Agostino S, Wang C. A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation. J Neurosurg Spine. 2007;7:47-53. 11. Fransen P. Increasing pedicle screw anchoring in the osteoporotic spine by cement injection through the implant. Technical note and report of three cases. J Neurosurg Spine. 2007;7:366-369. 12. Kim KH, Lee SH, Lee DY, Shim CS, Maeng DH. Anterior bone cement augmentation in anterior lumbar interbody fusion and percutaneous pedicle screw fixation in patients with osteoporosis. J Neurosurg Spine. 2010;12:525-532. 13. Tan JS, Bailey CS, Dvorak MF, Fisher CG, Cripton PA, Oxland TR. Cement augmentation of vertebral screws enhances the interface strength between interbody device and vertebral body. Spine (Phila Pa 1976). 2007;32:334-341. 14. Kim DH, Vaccaro AR. Osteoporotic compression fractures of the spine: current options and considerations for treatment. Spine J. 2006;6:479-487. 15. Knop C, Kranabetter T, Reinhold M, Blauth M. Combined posterior-anterior stabilisation of thoracolumbar injuries utilising a vertebral body replacing implant. Eur Spine J. 2009;18:949-963. 16. Lange U, Edeling S, Knop C, Bastian L, Oeser M, Krettek C, et al. Anterior vertebral body replacement with a titanium implant of adjustable height: a prospective clinical study. Eur Spine J. 2007;16: 161-172. 17. Lowe TG, Hashim S, Wilson LA, O’Brien MF, Smith DA, Diekmann MJ, et al. A biomechanical study of regional endplate strength and cage
morphology as it relates to structural interbody support. Spine (Phila Pa 1976). 2004;29:2389-2394. 18. Vieweg U, Solch O, Kalff R. Vertebral body replacement system Synex in unstable burst fractures of the thoracic and lumbar spine—a retrospective study with 30 patients [in German] Zentralbl Neurochir. 2003;64:58-64. 19. Skinner R, Maybee J, Transfeldt E, Venter R, Chalmers W. Experimental pullout testing and comparison of variables in transpedicular screw fixation. A biomechanical study. Spine (Phila Pa 1976). 1990;15:195-201. 20. Sugimoto Y, Tanaka M, Konishi H, Takigawa T, Nakanishi K, Misawa H, et al. Posterior spinal fusion using a pedicle nail system with polymethylmethacrylate in a paraplegic patient after vertebral collapse caused by osteoporosis. Spine J. 2009;9:e5-8. 21. Oppenlander ME, Bina R, Snyder LA, Dickman CA. Intravertebral polymethylmethacrylate augmentation of anterior cervical discectomy fusion and plating in the setting of osteoporosis. J Spinal Disord Tech. 2014; 27:185-188. 22. Kalteis T, Luring C, Gugler G, Zysk S, Caro W, Handel M, et al. Acute tissue toxicity of PMMA bone cements [in German] Z Orthop Ihre Grenzgeb. 2004;142:666-672. 23. Geiger F, Kafchitsas K, Rauschmann M. Anterior vertebroplasty of adjacent levels after vertebral body replacement. Eur Spine J. 2011;20:1385-1392.
Conflict of interest statement: This study was supported by a grant from the Spine Health Wooridul Hospital. Received 29 May 2016; accepted 9 August 2016 Citation: World Neurosurg. (2016). http://dx.doi.org/10.1016/j.wneu.2016.08.036 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved.
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