SPINE Volume 40, Number 3, pp 201-205 ©2015, Wolters Kluwer Health, Inc. All rights reserved.
SURGERY
Infection Rate After Minimally Invasive Noninstrumented Spinal Surgery Based on 4350 Procedures Mootaz Shousha, MD*† Dusan Cirovic,* and Heinrich Boehm, MD*
Study Design. Retrospective review of a prospectively collected database. Objective. To assess the rate of postoperative infection associated with minimally invasive noninstrumented spinal surgery. Summary of Background Data. Infection after spinal surgery results in significant morbidity, extended hospital stay, and significant costs. Minimally invasive spinal techniques require smaller incisions and less dissection, minimizing the risk of postoperative infection. Methods. Inclusion criteria were patients undergoing posterior spinal surgery using a tubular retractor system with the aid of operative microscope between June 1998 and November 2013. The analysis revealed a total number of 4350 procedures performed in 4037 patients (mean age = 53.2 yr). Sixty percent of the patients were male. The majority of procedures were performed in the lumbar spine (98.4%), and the indication was mostly degenerative in nature (96.9%). The databases were then reviewed for any infectious complications. Results. Postoperative infection was recorded in 4 patients (0.09%). All of them occurred in the lumbar region after discectomy. These patients presented with discitis and underwent revision in the form of open debridement and fusion. The time lapse between the index surgery and revision was 56 days. All 4 patients recovered, with a mean follow-up of 7.5 years. Conclusion. Infection rate after posterior transtubular microscopic assisted spinal surgery is very low (0.09%). Surgical debridement with fusion was the method of choice in treating such complications. This minimally invasive technique reduces markedly the risk of postoperative infection when compared with other large series published in the literature.
Key words: infection, minimally, invasive, spine, tubular, microscopic, discectomy, surgery, percutaneous, decompression. Level of Evidence: 4 Spine 2015;40:201–205
D
espite substantial advancements in the surgical care of spine disease, postoperative wound infections remain a relatively common source of morbidity and increased costs.1,2 Reported rates of spinal surgical site infections (SSIs) in the literature range from 0.7% to 16%.1,3–5 Spinal SSIs can be challenging to manage and often require prolonged hospitalizations, extended antibiotic therapy, repeated surgery for wound debridement, or delayed complications of deep infection.5 These factors serve to increase health care resource utilization and cost and may worsen overall clinical outcomes.6–8 Minimally invasive surgical techniques have been applied to spinal surgical cases for more than a decade now.9 Minimally invasive surgery is believed to provide a smaller corridor to the spine and results in less softtissue injury.10 On the basis of decreased tissue destruction, reduced blood loss, and shortened length of hospitalization, reported series have suggested a very low rate of SSIs after minimally invasive spine surgery.3–5 The purpose of this study was to investigate the incidence of postoperative infection after minimally invasive spine surgery since its introduction in our institution and to compare the obtained results with those published in the literature.
MATERIALS AND METHODS From the *Zentralklinik Bad Berka, Bad Berka, Thüringen, Germany; and †Alexandria University, Alexandria, Egypt. Acknowledgment date: June 12, 2014. First revision date: October 18, 2014. Acceptance date: October 26, 2014. The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. Relevant financial activities outside the submitted work: Consultancy, patents, royalties. Address correspondence and reprint requests to Mootaz Shousha, MD, Zentralklinik Bad Berka, Bad Berka, Thüringen 99438, Germany; E-mail: [email protected] DOI: 10.1097/BRS.0000000000000690 Spine
We performed a retrospective analysis of prospectively collected databases of consecutive patients who underwent minimally invasive noninstrumented spine surgery during a period of 15 years performed in a single institution under the supervision of the senior author. The first surgery was performed in June 1998 and the last one in November 2013, with a minimum follow-up of 6 months.
Inclusion Criteria and Surgical Technique Minimally invasive noninstrumentated spine surgery was defined as any spinal surgery performed using a tubular retractor system. All procedures were performed under general www.spinejournal.com
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SURGERY anesthesia, with the patient placed in the prone position on the operating table. Standard surgical scrub, preparation, and draping were performed using reusable surgical drapes. All patients received a single dose of intravenous broad-spectrum antibiotic immediately preoperatively. The image intensifier remained in the lateral view within the operation area. After the skin incision of 15 mm, both the fascia and the paraspinal muscles were dilated with 3 sequentially placed dilators till the working channel could be brought in (Figure 1). We used work channels with an outside diameter of 12 and 14 mm. Next, a lateral fluoroscopic image was used to confirm correct localization of the tubular retractor. After attaching the grip to the tubular working channel, all further work steps in the fundamental technique were performed under direct vision with the aid of a microscope. At the end of the procedure, no surgical drain was inserted. The fascia was then closed with 1 suture and the skin was closed with 2 subcutaneous stitches, followed by application of Band-Aid to the wound. No postoperative antibiotic was administered except in case of an incidental dural tear and in cases operated on for epidural abscess. Mobilization was allowed after 4 hours without brace except in cases with incidental dural tear, where flat bed rest was advised for 3 days.
Exclusion Criteria Patients undergoing open microdiscectomy with subperiosteal dissection and application of a Caspar retractor were excluded from this study. Furthermore, patients undergoing minimally invasive fusion or percutaneous instrumentation were not included in this work. No intradural pathologies were addressed in this technique.
Definition of Postoperative Infection Postoperative infection was defined on the basis of 2 mainstays beside the clinical picture. The postoperative laboratory data represented the first pillar in the diagnosis. Elevation of the inflammatory parameters (leukocytic count, C-reactive protein, and erythrocyte sedimentation rate) was used as an indicator to detect the occurrence of postoperative infection. Magnetic resonance imaging was the second pillar and represented a keystone in the evaluation of postoperative infection. This was
Figure 1. Sequential dilators, the working tubular channel, and the hand grip used to hold the retractor.
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Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
performed in any patient with elevated inflammatory parameters to exclude or confirm the diagnosis of infection and to evaluate the depth of infection. Finally, the surgical wound was expected for local signs of inflammation or infection.
RESULTS The analysis of our database revealed a total number of 4350 patients undergoing 4350 minimally invasive spinal procedures performed using a tubular retractor and meeting the aforementioned inclusion criteria. The mean age of this group of patients was 53.2 years (ranging from 7 to 95 yr). The male to female ratio was 3:2. The region of surgery was lumbar in 4280 patients (98.4%), thoracic in 40 patients (0.92%), and cervical in 30 patients (0.68%). The indication for surgery was degenerative disease including disc herniation in 4216 patients (96.9%), epidural abscess formation in 48 patients (1.1%), tumor in 13 patients (0.3%), and miscellaneous in the remaining 73 patients (1.7%). Among the 4350 procedures, the total number of patients experiencing postoperative infection was 4 (0.09%) (Figures 2, 3). These were 2 males and 2 females and had a mean age of 40.8 years. The surgical indication in all 4 patients was degenerative disc herniation in the lumbar region. The 4 patients presented with deep infection in the form of discitis and underwent revision with surgical debridement, discectomy, and fusion of the affected segment. The time lapse between the index surgery and revision ranged from 18 to 104 days (mean = 56 d). The causative organisms could be identified in 4 patients (Staphylococcus aureus in 1, Staphylococcus epidermidis in 2, and Probiolum agnes in 1). All 4 patients recovered with successful fusion. No pseudoarthrosis was recorded. The mean follow-up period for this subgroup of patients was 7.5 years (Table 1).
DISCUSSION SSIs after spinal surgery remain a serious complication that can lead to major complications and worse outcomes.3 Reported rates of spinal SSIs in the literature range from 0.7% to 16%.1,3–5,11 Recently, the Scoliosis Research Society Morbidity and Mortality Committee has reported on the rates of infection after spine surgery. In total, 108.419 cases were identified, with an overall total infection rate of 2.1% (superficial = 0.8%; deep = 1.3%).12 The additional expense involved in treating patients with deep postoperative spinal infections was found to increase the total cost of care more than 4 times.6 In 1964, a true paradigm shift began with the minimally invasive approach to lumbar disc disease.13 From 1977 to 1979, Yasargil,14 Caspar,15 and Williams16 pioneered the use of the operating microscope and microsurgical techniques for the treatment of lumbar disc disease. The technique of microdiscectomy was further optimized at the end of the 1990s through the introduction of tubular retractors using the technique of soft-tissue dilatation instead of subperiosteal dissection.13,17 Since then, several authors were interested to evaluate the results of this minimally invasive technique with regard to the infection rate.3–5,18 Most of the available publications deal with a mixed patient population including February 2015
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE140768_LR 202
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Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
Figure 2. A, Axial magnetic resonance image of a 33-year-old female patient who presented 49 days after microscopic assisted percutaneous transtubular discectomy L5–S1 with deep infection in the form of discitis. This was treated by open surgical debridement and posterior lumbar interbody fusion. The plain radiograph shows successful fusion, with a 2-year follow-up (B).
patients undergoing both instrumented and noninstrumented minimally invasive spinal procedures. McGirt et al4 analyzed perioperative SSI after minimally invasive versus open posterior/transforaminal lumbar interbody fusion. They reported that the minimally invasive technique was associated with a decreased incidence of infection when used in 2-level fusion. However, they did not find a significant difference in the incidence of infection for 1-level fusion procedures.4 Similarly, Parker et al5 conducted a literature review of postoperative infection after minimally invasive versus open transforaminal lumbar interbody fusion. They concluded that the minimally invasive technique is associated with a decreased incidence of SSI in the literature.5 An interesting study has been conducted by O’Toole et al3 in 2009. They evaluated SSI after minimally invasive spinal surgery performed by a transtubular approach and reported an overall incidence of 0.22%.3 Analysis of their data revealed an incidence of 0.74% in the instrumented procedures. Their total number of case patients undergoing noninstrumented procedures was 1039. In this group of patients, an infection rate of 0.10% was reported.3 Similarly, we evaluated in the current series the rate of infection after minimally invasive spinal procedures performed by a posterior approach with the aid of tubular retractors and visual control with an operative microscope. In our series, only noninstrumented procedures were included. We revealed an incidence of 0.09% for
postoperative infection. This compares well with the figures obtained by O’Toole et al. Although the number of patients included in our series was 4-fold, the rate of postoperative infection remained more or less similar to that obtained by O’Toole et al. The reason for this very low incidence of postoperative infection in both studies, compared with many other articles dealing with minimally invasive techniques, might be the use of tubular retractors with small diameters (max. 14 mm) in all of the patients.3,19 Because tubular retractors are introduced through serial soft-tissue dilatation without subperiosteal muscle dissection, this not only minimizes softtissue trauma but also reduces the dead space in the operative site to a minimum and reduces the surface area exposed during surgery.3,19 Two further technical points are of concern. We left the image intensifier draped in the operation area. This did not seem to have a negative effect as demonstrated by the very low incidence of postoperative infection. Biswas et al20 evaluated the sterility of C-arm drapes during spinal surgery. They found that the upper portions of the C-arm clearly exhibited the greatest rates of contamination and recommended to avoid contact with these areas to decrease the risk of intraoperative contamination and possibly postoperative infection as well.20 We fully agree with the conclusion of this work because we also routinely consider the top portion of the C-arm drape to be potentially nonsterile. Taking this into consideration and
Figure 3. A, Sagittal magnetic resonance image of a 50-year-old male patient who presented 53 days after microscopic assisted percutaneous transtubular discectomy L4–L5 with deep infection in the form of discitis and epidural abscess. This was treated by open surgical debridement and anterior lumbar interbody fusion. The plain radiograph shows successful fusion, with a 10year follow-up (B). Spine
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Healed Unacid (3 mo)
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MAPN indicates microscopic assisted percutaneous nucleotomy; PLIF, posterior lumbar interbody fusion; ALIF, anterior lumbar interbody fusion.
None Fusion (PLIF) 18 d Discitis 115 min 43 4
M
MAPN
Senior L4–L5 surgeon
Diabetes mellitus, Staphylococcus chronic epidermidis pancreatitis
Healed Flucloxacillin (3 mo) None Fusion (ALIF) 53 d Probiolum agnes Discitis 145 min Junior surgeon L4–L5 50 3
M
MAPN
None Discitis 37 2
F
MAPN
40 min
None
Healed Re-MAPN 6 wk after the index Linezolid surgery due to (3 mo) reprolapse Fusion Staphylococcus 104 d (PLIF) epidermidis Senior L5–S1 surgeon
None 120 min Junior surgeon L5–S1 33
F
MAPN
Discitis
Staphylococcus aureus
49 d
Fusion (PLIF)
Debridement by MAPN-technique 6 wk Clindamycin Healed after the index (3 mo) surgery due to infection
Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
1
Organism Operative Time Infection Risk Factors Surgeon Index Sex Surgery Level Age, yr
TABLE 1. Clinical Data of the 4 Patients Experiencing Postoperative Infection
Time Final Surgery Before Lapse Treatment Fusion
Antibiotic
Outcome
SURGERY
after identification of the operated level, the image intensifier was moved cranially to give place to the operating microscope. There was no need to bring the image intensifier out of the operation area in any case. We think that leaving it sterile in the operation area has 2 advantages: first, further photographs could be taken with no time loss. Second, bringing it several times in and out of the operation area might be more harmful to the sterility. The second point is the sterility of the operating microscope. We were astonished to find a recent study published by Bible et al21 in 2012. They detected significant bacterial contamination of the operative microscope after spine surgery and recommended changing the gloves after making adjustments to the optic eyepieces.21 In our experience, changing the gloves after adjustment of the eyepieces was never undertaken. This did not seem to negatively influence our results in comparison with the available literature. Finally, 2 main limitations are present in our study. First, it does not involve a control group of patients, in whom the same procedures were performed by a standard open technique. The reason for this is that we have been using tubular retractors since their development in 1998 and have abandoned the classical open or mini-open techniques since that time. A double- or multicenter study aiming for comparison was not intended in this work to minimize the variables by performing the review in a single institution. The second limitation of this work is the lack of evaluation of preoperative risk factors for SSIs. The very small number of infected cases in this study precludes useful analysis of risk factors for infection as performed in previously published case-control studies. A similar explanation with more details has been clarified by O’Toole et al3 in their publication. Despite these 2 limitations, we think that the results obtained in this work demonstrate a possible advantage to minimally invasive noninstrumented transtubular technique in spinal surgery, namely, a reduction in postoperative wound infection.
CONCLUSION Infection rate after minimally invasive noninstrumented posterior transtubular microscopic assisted spinal surgery is very low. This was recorded to be 0.09% in the current series and agrees with the results obtained by other authors applying the same technique. The figure obtained is extremely low when compared with publications applying standard open or microscopic assisted mini-open techniques. The salvage surgery in case of postoperative infection in this work was spinal fusion by a standard open technique.
➢ Key Points Among 4350 minimally invasive spinal procedures, the postoperative infection rate was found to be 0.09%. Presentation was mostly within the first 2 months. February 2015
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SURGERY Postoperative infection occurred exclusively in cases undergoing discectomy and presented with discitis. Surgical debridement and fusion were performed in the 4 patients, and all of them recovered. The figure obtained is very low when compared with other series using mini-open techniques.
References
1. Beiner JM, Grauer J, Kwon BK, et al. Postoperative wound infections of the spine [review]. Neurosurg Focus 2003;15:E14. 2. Olsen MA, Mayfield J, Lauryssen C, et al. Risk factors for surgical site infection in spinal surgery. J Neurosurg 2003;98(suppl):149–55. 3. O’Toole JE, Eichholz KM, Fessler RG. Surgical site infection rates after minimally invasive spinal surgery. J Neurosurg Spine 2009;11:471–6. 4. McGirt MJ, Parker SL, Lerner J, et al. Comparative analysis of perioperative surgical site infection after minimally invasive versus open posterior/transforaminal lumbar interbody fusion: analysis of hospital billing and discharge data from 5170 patients. J Neurosurg Spine 2011;14:771–8. 5. Parker SL, Adogwa O, Witham TF, et al. Post-operative infection after minimally invasive versus open transforaminal lumbar interbody fusion (TLIF): literature review and cost analysis. Minim Invasive Neurosurg 2011;54:33–7. 6. Calderone RR, Garland DE, Capen DA, et al. Cost of medical care for postoperative spinal infections. Orthop Clin N Am 1996;27:171–82. 7. Calderone RR, Thomas JC Jr, Haye W, et al. Outcome assessment in spinal infections. Orthop Clin N Am 1996;27:201–5. 8. Whitehouse JD, Friedman ND, Kirkland KB, et al. The impact of surgical-site infections following orthopedic surgery at a community hospital and a university hospital: adverse quality of life, excess length of stay, and extra cost. Infect Control Hosp Epidemiol. 2002;23:183–9.
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Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
9. Fessler RG, O’Toole JE, Eichholz KM, et al. The development of minimally invasive spine surgery. Neurosurg Clin N Am 2006;17:401–9. 10. Senker W, Meznik C, Avian A, et al. Perioperative morbidity and complications in minimal access surgery techniques in obese patients with degenerative lumbar disease. Eur Spine J 2011;20:1182–7. 11. Weinstein MA, McCabe JP, Cammisa FP Jr. Postoperative spinal wound infection: a review of 2,391 consecutive index procedures. J Spinal Disord 2000;13:422–6. 12. Smith JS, Shaffrey CI, Sansur CA, et al; Scoliosis Research Society Morbidity and Mortality Committee. Rates of infection after spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee. Spine (Phila Pa 1976) 2011;36:556–63. 13. Maroon JC. Current concepts in minimally invasive discectomy. Neurosurgery 2002;51(suppl):S137–45. 14. Yasargil MG. Microsurgical operation for herniated disc. In: Wullenweber R, Brock M, Hamer J, Klinger M, Spoerri O, eds. Advances in Neurosurgery. Berlin, Germany: Springer-Verlag; 1977:81–3. 15. Caspar W: A new surgical procedure for lumbar disc herniation causing less tissue damage through a microsurgical approach. In: Wullenweber R, Brock M, Hamer J, Klinger M, Spoerri O, eds. Advances in Neurosurgery. Berlin, Germany: Springer-Verlag; 1977:74–7. 16. Williams RW. Microlumbar discectomy: a conservative surgical approach to the virgin herniated lumbar disc. Spine (Phila Pa 1976) 1978;3:175–82. 17. Greiner-Perth R, Böhm H, El Saghir H. Microscopically assisted percutaneous nucleotomy, an alternative minimally invasive procedure for the operative treatment of lumbar disc herniation: preliminary results. Neurosurg Rev 2002;25:225–7. 18. Li CH, Yew AY, Kimball JA, et al. Comparison of operating field sterility in open versus minimally invasive microdiscectomies of the lumbar spine. Surg Neurol Int 2013;4(suppl 5):S295–8. 19. Kim YB, Hyun SJ. Clinical applications of the tubular retractor on spinal disorders. J Korean Neurosurg Soc 2007;42:245–50. 20. Biswas D, Bible JE, Whang PG, et al. Sterility of C-arm fluoroscopy during spinal surgery. Spine (Phila Pa 1976) 2008;33:1913–7. 21. Bible JE, O’Neill KR, Crosby CG, et al. Microscope sterility during spine surgery. Spine (Phila Pa 1976) 2012;37:623–7.
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Infection Rate After Minimally Invasive Noninstrumented Spinal Surgery Based on 4350 Procedures Mootaz Shousha, MD*† Dusan Cirovic,* and Heinrich Boehm, MD*
Study Design. Retrospective review of a prospectively collected database. Objective. To assess the rate of postoperative infection associated with minimally invasive noninstrumented spinal surgery. Summary of Background Data. Infection after spinal surgery results in significant morbidity, extended hospital stay, and significant costs. Minimally invasive spinal techniques require smaller incisions and less dissection, minimizing the risk of postoperative infection. Methods. Inclusion criteria were patients undergoing posterior spinal surgery using a tubular retractor system with the aid of operative microscope between June 1998 and November 2013. The analysis revealed a total number of 4350 procedures performed in 4037 patients (mean age = 53.2 yr). Sixty percent of the patients were male. The majority of procedures were performed in the lumbar spine (98.4%), and the indication was mostly degenerative in nature (96.9%). The databases were then reviewed for any infectious complications. Results. Postoperative infection was recorded in 4 patients (0.09%). All of them occurred in the lumbar region after discectomy. These patients presented with discitis and underwent revision in the form of open debridement and fusion. The time lapse between the index surgery and revision was 56 days. All 4 patients recovered, with a mean follow-up of 7.5 years. Conclusion. Infection rate after posterior transtubular microscopic assisted spinal surgery is very low (0.09%). Surgical debridement with fusion was the method of choice in treating such complications. This minimally invasive technique reduces markedly the risk of postoperative infection when compared with other large series published in the literature.
Key words: infection, minimally, invasive, spine, tubular, microscopic, discectomy, surgery, percutaneous, decompression. Level of Evidence: 4 Spine 2015;40:201–205
D
espite substantial advancements in the surgical care of spine disease, postoperative wound infections remain a relatively common source of morbidity and increased costs.1,2 Reported rates of spinal surgical site infections (SSIs) in the literature range from 0.7% to 16%.1,3–5 Spinal SSIs can be challenging to manage and often require prolonged hospitalizations, extended antibiotic therapy, repeated surgery for wound debridement, or delayed complications of deep infection.5 These factors serve to increase health care resource utilization and cost and may worsen overall clinical outcomes.6–8 Minimally invasive surgical techniques have been applied to spinal surgical cases for more than a decade now.9 Minimally invasive surgery is believed to provide a smaller corridor to the spine and results in less softtissue injury.10 On the basis of decreased tissue destruction, reduced blood loss, and shortened length of hospitalization, reported series have suggested a very low rate of SSIs after minimally invasive spine surgery.3–5 The purpose of this study was to investigate the incidence of postoperative infection after minimally invasive spine surgery since its introduction in our institution and to compare the obtained results with those published in the literature.
MATERIALS AND METHODS From the *Zentralklinik Bad Berka, Bad Berka, Thüringen, Germany; and †Alexandria University, Alexandria, Egypt. Acknowledgment date: June 12, 2014. First revision date: October 18, 2014. Acceptance date: October 26, 2014. The manuscript submitted does not contain information about medical device(s)/drug(s). No funds were received in support of this work. Relevant financial activities outside the submitted work: Consultancy, patents, royalties. Address correspondence and reprint requests to Mootaz Shousha, MD, Zentralklinik Bad Berka, Bad Berka, Thüringen 99438, Germany; E-mail: [email protected] DOI: 10.1097/BRS.0000000000000690 Spine
We performed a retrospective analysis of prospectively collected databases of consecutive patients who underwent minimally invasive noninstrumented spine surgery during a period of 15 years performed in a single institution under the supervision of the senior author. The first surgery was performed in June 1998 and the last one in November 2013, with a minimum follow-up of 6 months.
Inclusion Criteria and Surgical Technique Minimally invasive noninstrumentated spine surgery was defined as any spinal surgery performed using a tubular retractor system. All procedures were performed under general www.spinejournal.com
201
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE140768_LR 201
24/12/14 9:38 PM
SURGERY anesthesia, with the patient placed in the prone position on the operating table. Standard surgical scrub, preparation, and draping were performed using reusable surgical drapes. All patients received a single dose of intravenous broad-spectrum antibiotic immediately preoperatively. The image intensifier remained in the lateral view within the operation area. After the skin incision of 15 mm, both the fascia and the paraspinal muscles were dilated with 3 sequentially placed dilators till the working channel could be brought in (Figure 1). We used work channels with an outside diameter of 12 and 14 mm. Next, a lateral fluoroscopic image was used to confirm correct localization of the tubular retractor. After attaching the grip to the tubular working channel, all further work steps in the fundamental technique were performed under direct vision with the aid of a microscope. At the end of the procedure, no surgical drain was inserted. The fascia was then closed with 1 suture and the skin was closed with 2 subcutaneous stitches, followed by application of Band-Aid to the wound. No postoperative antibiotic was administered except in case of an incidental dural tear and in cases operated on for epidural abscess. Mobilization was allowed after 4 hours without brace except in cases with incidental dural tear, where flat bed rest was advised for 3 days.
Exclusion Criteria Patients undergoing open microdiscectomy with subperiosteal dissection and application of a Caspar retractor were excluded from this study. Furthermore, patients undergoing minimally invasive fusion or percutaneous instrumentation were not included in this work. No intradural pathologies were addressed in this technique.
Definition of Postoperative Infection Postoperative infection was defined on the basis of 2 mainstays beside the clinical picture. The postoperative laboratory data represented the first pillar in the diagnosis. Elevation of the inflammatory parameters (leukocytic count, C-reactive protein, and erythrocyte sedimentation rate) was used as an indicator to detect the occurrence of postoperative infection. Magnetic resonance imaging was the second pillar and represented a keystone in the evaluation of postoperative infection. This was
Figure 1. Sequential dilators, the working tubular channel, and the hand grip used to hold the retractor.
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Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
performed in any patient with elevated inflammatory parameters to exclude or confirm the diagnosis of infection and to evaluate the depth of infection. Finally, the surgical wound was expected for local signs of inflammation or infection.
RESULTS The analysis of our database revealed a total number of 4350 patients undergoing 4350 minimally invasive spinal procedures performed using a tubular retractor and meeting the aforementioned inclusion criteria. The mean age of this group of patients was 53.2 years (ranging from 7 to 95 yr). The male to female ratio was 3:2. The region of surgery was lumbar in 4280 patients (98.4%), thoracic in 40 patients (0.92%), and cervical in 30 patients (0.68%). The indication for surgery was degenerative disease including disc herniation in 4216 patients (96.9%), epidural abscess formation in 48 patients (1.1%), tumor in 13 patients (0.3%), and miscellaneous in the remaining 73 patients (1.7%). Among the 4350 procedures, the total number of patients experiencing postoperative infection was 4 (0.09%) (Figures 2, 3). These were 2 males and 2 females and had a mean age of 40.8 years. The surgical indication in all 4 patients was degenerative disc herniation in the lumbar region. The 4 patients presented with deep infection in the form of discitis and underwent revision with surgical debridement, discectomy, and fusion of the affected segment. The time lapse between the index surgery and revision ranged from 18 to 104 days (mean = 56 d). The causative organisms could be identified in 4 patients (Staphylococcus aureus in 1, Staphylococcus epidermidis in 2, and Probiolum agnes in 1). All 4 patients recovered with successful fusion. No pseudoarthrosis was recorded. The mean follow-up period for this subgroup of patients was 7.5 years (Table 1).
DISCUSSION SSIs after spinal surgery remain a serious complication that can lead to major complications and worse outcomes.3 Reported rates of spinal SSIs in the literature range from 0.7% to 16%.1,3–5,11 Recently, the Scoliosis Research Society Morbidity and Mortality Committee has reported on the rates of infection after spine surgery. In total, 108.419 cases were identified, with an overall total infection rate of 2.1% (superficial = 0.8%; deep = 1.3%).12 The additional expense involved in treating patients with deep postoperative spinal infections was found to increase the total cost of care more than 4 times.6 In 1964, a true paradigm shift began with the minimally invasive approach to lumbar disc disease.13 From 1977 to 1979, Yasargil,14 Caspar,15 and Williams16 pioneered the use of the operating microscope and microsurgical techniques for the treatment of lumbar disc disease. The technique of microdiscectomy was further optimized at the end of the 1990s through the introduction of tubular retractors using the technique of soft-tissue dilatation instead of subperiosteal dissection.13,17 Since then, several authors were interested to evaluate the results of this minimally invasive technique with regard to the infection rate.3–5,18 Most of the available publications deal with a mixed patient population including February 2015
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE140768_LR 202
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Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
Figure 2. A, Axial magnetic resonance image of a 33-year-old female patient who presented 49 days after microscopic assisted percutaneous transtubular discectomy L5–S1 with deep infection in the form of discitis. This was treated by open surgical debridement and posterior lumbar interbody fusion. The plain radiograph shows successful fusion, with a 2-year follow-up (B).
patients undergoing both instrumented and noninstrumented minimally invasive spinal procedures. McGirt et al4 analyzed perioperative SSI after minimally invasive versus open posterior/transforaminal lumbar interbody fusion. They reported that the minimally invasive technique was associated with a decreased incidence of infection when used in 2-level fusion. However, they did not find a significant difference in the incidence of infection for 1-level fusion procedures.4 Similarly, Parker et al5 conducted a literature review of postoperative infection after minimally invasive versus open transforaminal lumbar interbody fusion. They concluded that the minimally invasive technique is associated with a decreased incidence of SSI in the literature.5 An interesting study has been conducted by O’Toole et al3 in 2009. They evaluated SSI after minimally invasive spinal surgery performed by a transtubular approach and reported an overall incidence of 0.22%.3 Analysis of their data revealed an incidence of 0.74% in the instrumented procedures. Their total number of case patients undergoing noninstrumented procedures was 1039. In this group of patients, an infection rate of 0.10% was reported.3 Similarly, we evaluated in the current series the rate of infection after minimally invasive spinal procedures performed by a posterior approach with the aid of tubular retractors and visual control with an operative microscope. In our series, only noninstrumented procedures were included. We revealed an incidence of 0.09% for
postoperative infection. This compares well with the figures obtained by O’Toole et al. Although the number of patients included in our series was 4-fold, the rate of postoperative infection remained more or less similar to that obtained by O’Toole et al. The reason for this very low incidence of postoperative infection in both studies, compared with many other articles dealing with minimally invasive techniques, might be the use of tubular retractors with small diameters (max. 14 mm) in all of the patients.3,19 Because tubular retractors are introduced through serial soft-tissue dilatation without subperiosteal muscle dissection, this not only minimizes softtissue trauma but also reduces the dead space in the operative site to a minimum and reduces the surface area exposed during surgery.3,19 Two further technical points are of concern. We left the image intensifier draped in the operation area. This did not seem to have a negative effect as demonstrated by the very low incidence of postoperative infection. Biswas et al20 evaluated the sterility of C-arm drapes during spinal surgery. They found that the upper portions of the C-arm clearly exhibited the greatest rates of contamination and recommended to avoid contact with these areas to decrease the risk of intraoperative contamination and possibly postoperative infection as well.20 We fully agree with the conclusion of this work because we also routinely consider the top portion of the C-arm drape to be potentially nonsterile. Taking this into consideration and
Figure 3. A, Sagittal magnetic resonance image of a 50-year-old male patient who presented 53 days after microscopic assisted percutaneous transtubular discectomy L4–L5 with deep infection in the form of discitis and epidural abscess. This was treated by open surgical debridement and anterior lumbar interbody fusion. The plain radiograph shows successful fusion, with a 10year follow-up (B). Spine
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Healed Unacid (3 mo)
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MAPN indicates microscopic assisted percutaneous nucleotomy; PLIF, posterior lumbar interbody fusion; ALIF, anterior lumbar interbody fusion.
None Fusion (PLIF) 18 d Discitis 115 min 43 4
M
MAPN
Senior L4–L5 surgeon
Diabetes mellitus, Staphylococcus chronic epidermidis pancreatitis
Healed Flucloxacillin (3 mo) None Fusion (ALIF) 53 d Probiolum agnes Discitis 145 min Junior surgeon L4–L5 50 3
M
MAPN
None Discitis 37 2
F
MAPN
40 min
None
Healed Re-MAPN 6 wk after the index Linezolid surgery due to (3 mo) reprolapse Fusion Staphylococcus 104 d (PLIF) epidermidis Senior L5–S1 surgeon
None 120 min Junior surgeon L5–S1 33
F
MAPN
Discitis
Staphylococcus aureus
49 d
Fusion (PLIF)
Debridement by MAPN-technique 6 wk Clindamycin Healed after the index (3 mo) surgery due to infection
Infection Rate After Minimally Invasive Spinal Surgery • Shousha et al
1
Organism Operative Time Infection Risk Factors Surgeon Index Sex Surgery Level Age, yr
TABLE 1. Clinical Data of the 4 Patients Experiencing Postoperative Infection
Time Final Surgery Before Lapse Treatment Fusion
Antibiotic
Outcome
SURGERY
after identification of the operated level, the image intensifier was moved cranially to give place to the operating microscope. There was no need to bring the image intensifier out of the operation area in any case. We think that leaving it sterile in the operation area has 2 advantages: first, further photographs could be taken with no time loss. Second, bringing it several times in and out of the operation area might be more harmful to the sterility. The second point is the sterility of the operating microscope. We were astonished to find a recent study published by Bible et al21 in 2012. They detected significant bacterial contamination of the operative microscope after spine surgery and recommended changing the gloves after making adjustments to the optic eyepieces.21 In our experience, changing the gloves after adjustment of the eyepieces was never undertaken. This did not seem to negatively influence our results in comparison with the available literature. Finally, 2 main limitations are present in our study. First, it does not involve a control group of patients, in whom the same procedures were performed by a standard open technique. The reason for this is that we have been using tubular retractors since their development in 1998 and have abandoned the classical open or mini-open techniques since that time. A double- or multicenter study aiming for comparison was not intended in this work to minimize the variables by performing the review in a single institution. The second limitation of this work is the lack of evaluation of preoperative risk factors for SSIs. The very small number of infected cases in this study precludes useful analysis of risk factors for infection as performed in previously published case-control studies. A similar explanation with more details has been clarified by O’Toole et al3 in their publication. Despite these 2 limitations, we think that the results obtained in this work demonstrate a possible advantage to minimally invasive noninstrumented transtubular technique in spinal surgery, namely, a reduction in postoperative wound infection.
CONCLUSION Infection rate after minimally invasive noninstrumented posterior transtubular microscopic assisted spinal surgery is very low. This was recorded to be 0.09% in the current series and agrees with the results obtained by other authors applying the same technique. The figure obtained is extremely low when compared with publications applying standard open or microscopic assisted mini-open techniques. The salvage surgery in case of postoperative infection in this work was spinal fusion by a standard open technique.
➢ Key Points Among 4350 minimally invasive spinal procedures, the postoperative infection rate was found to be 0.09%. Presentation was mostly within the first 2 months. February 2015
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SURGERY Postoperative infection occurred exclusively in cases undergoing discectomy and presented with discitis. Surgical debridement and fusion were performed in the 4 patients, and all of them recovered. The figure obtained is very low when compared with other series using mini-open techniques.
References
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