For pyogenic spondylitis, conservative management

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1 SPINE Volume 41, Number 17, pp E1022 E1029 ß 2016 Wolters Kluwer Health, Inc. All rights reserved CLINICAL CASE SERIES Posterior Only Approach for Lumbar Pyogenic Spondylitis With Short Instrumentation and Prolonged Suction Drainage Yong-Min Kim, MD and Seung-Myung Choi, MD Study design. A single-institution, single-surgeon retrospective review. Objective. To assess the efficacy of posterior only approach with short instrumentation and prolonged suction drainage in managing lumbar pyogenic spondylitis. Summary of Background Data. Several methods of posterior surgical treatment for pyogenic spondylitis have been reported, there have been few reports regarding the efficacy of posterior only approach with short instrumentation including even inflamed segment. Methods. Thirty-three patients with lumbar pyogenic spondylitis who underwent posterior decompression and lumbar interbody fusion with short instrumentation including the inflamed segment and catheter drainage were enrolled. Clinically infection control (erythrocyte sedimentation rate and C-reactive protein normalization time) and onset of ambulation were reviewed. Moreover, achievement of fusion and changes of sagittal alignment were investigated radiologically. Results. In all 33 cases, infection was controlled successfully without any recurrence. There was no breakage of implant. Postoperative interval to normalization of erythrocyte sedimentation rate was average 69.4 days and C-reactive protein was 25.4 days, respectively. Ambulation was started at average 5.8 postoperative days. Successful interbody fusion was confirmed radiologically in all the cases at a mean of 5.4 months. Sagittal angle of fixed segment was average 6.9 degrees of lordosis before operation, which became more lordotic to 11.5 degrees From the Department of Orthopedic Surgery, School of Medicine, Chungbuk National University, Cheongju, Korea. Acknowledgment date: September 10, First revision date: November 17, Second revision date: December 21, Acceptance date: February 2, The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication. NIH funds were received in support of this work. No relevant financial activities outside the submitted work. Address correspondence and reprint requests to Seung-Myung Choi, MD, Department of Orthopedic Surgery, Chungbuk National University Hospital, 776, 1sunhwan-ro, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do, , Republic of Korea; davidchoi1530@gmail.com DOI: /BRS just after operation, but decreased to 4.7 degrees of lordosis at the final follow up. Actually final sagittal alignment was almost same as preoperative status (P ¼ 0.24). Conclusion. By achieving favorable clinical and radiological results, short instrumentation and prolonged suction drainage with posterior only approach seemed to be an effective method in managing lumbar pyogenic spondylitis. Key words: early ambulation, lumbar pyogenic spondylitis, maintenance, posterior only approach, prolonged suction drainage, sagittal alignment, short instrumentation, solid fusion. Level of Evidence: 3 Spine 2016;41:E1022 E1029 For pyogenic spondylitis, conservative management with antibiotic therapy is tried first but surgery may be necessary if the infection is not controlled by conservative way, or if neurological deficit and/or instability is present. An anterior approach is advantageous by performing direct extirpation of the lesion and bone grafting, but requires long-term bed rest and often results in kyphotic deformity. On the other hand, posterior approach using instrumentation provides spinal stability, although it has been regarded as inappropriate to be used in infectionrelated conditions because of the risk that the metal devices would be an obstacle on infection treatment. In a previous report, we showed that prolonged drainage resulted in successful results in patients with deep wound infections after short posterior lumbar instrumentation. 1 Based on this experience, we managed lumbar pyogenic spondylitis with similar approach that is, long-term drainage and antibiotic regimen after extirpation of infectious lesion. MATERIALS A total of 33 patients who underwent short instrumentation and catheter drainage after extirpation of infectious lesion via posterior only approach at our institute between October 1997 and January 2011 were enrolled. Indications were pyogenic spondylodiscitis that had not responded to antibiotic treatment, apparent, or impending neurologic E September 2016

2 TABLE 1. Clinical Profiles of the Patients Who Underwent Posterior Instrumentation and Fusion With Transpedicular Screw System Sex Age (Yrs) Infection Level Destruction Grade compromise by abscess, so on and progressive bony destruction around the disc in previously ambulatory subjects with rather competent general condition. Mean age of 33 patients was 63.7 years (range, yrs) (Table 1). The mean postoperative follow-up period was 43.7 months (range, months). Initial erythrocyte sedimentation rate (ESR) was average 64.7 mm/h and C- reactive protein (CRP) was 9.8 mg/dl. Epidural Abscess Psoas Abscess Posterior Column Abscess Infected Vertebrae Preoperatively, the extent of vertebral body destruction, presence of an epidural abscess, or a psoas abscess was assessed on MRI (Table 1). Twenty-five patients had singlesegment infection and eight patients had multilevel involvement (two disc levels were affected in seven patients and three discs in one patient). Extent of Vertebral Body Destruction A new classification of the extent of vertebral body destruction from grade I to grade IV using the sagittal and coronal MRI images was developed. Grade I was defined as infection confined to the intervertebral disc space only, grade II as involvement of the end plate and vertebral body less than 1/3 of vertebral height, grade III as more than 1/3 and less than 2/3. Grade IV is the severest, destruction more than 2/3 of vertebral height (Figure 1(A C)). To determine the Fixation Level 1 M 70 L2-5 II, III, I L2-5 Lt. L2-S1, Rt. (þ) L2-S1 L3-S1 2 M 55 L5-S1 II L4-S1 Lt. L5-S1 ( ) L5-S1 3 F 67 L3-4 II L3-4 Both L3-4 ( ) L3 5 4 F 77 L2-3 III L1-4 Rt. L2-4 ( ) L2-4 5 F 59 L4-S1 I, I L4-S1 Both L4-5 (þ) L4-S1 6 F 63 L5-S1 III L5-S1 ( ) ( ) L5-S1 7 M 42 L5-S1 I L5-S1 Lt. L5-S1 ( ) L5-S1 8 M 60 L4-5 II L4-5 Lt. L4-S1, Rt. ( ) L4-S1 L4 9 F 72 L4-5 III L4-5 Lt. L4-S1 (þ) L4-S1 10 M 50 L4-5 I L4-S1 Lt. L4-S1, Rt. ( ) L4-S1 L5-S1 11 F 66 L4-5 II L4-5 Both L4-5 ( ) L4-S1 12 M 75 L3-4 I L3-4 Rt. L3-4 ( ) L M 53 L2-3 III L2-3 Rt. L2-3 (þ) L M 69 L1-2 III L1-2 Rt. L3-5 ( ) T12-L3 15 M 69 L3-4 III L3-4 Rt. L3-5 (þ) L F 68 L4-5 II L4-5 ( ) ( ) L3-S1 17 M 68 L2-3 I ( ) ( ) ( ) L M 70 L3-5 I, I L3-5 Lt. L3-5 (þ) L2-S1 19 F 74 L4-S1 I, I L4-S1 Lt. L4-S1 (þ) L4-S1 20 F 61 L4-5 II L4-5 ( ) ( ) L4-S1 21 F 69 L4-5 I ( ) ( ) ( ) L M 60 L1-2 I ( ) Rt. L1-2 ( ) L M 64 L3-5 I, I L2-5 ( ) (þ) L3-S1 24 F 68 L4-S1 I, I L4-S1 Rt. L4-5, Lt. L4- (þ) L4-S1 S1 25 F 70 L4-5 I L4-5 Rt. L4-5 ( ) L F 52 L4-5 II L4-5 Lt. L4-5 ( ) L4-S1 27 M 58 L4-S1 I, I L4-S1 Rt. L5-S1 (þ) L4-S1 28 F 68 L5-S1 III L4-S1 ( ) ( ) L5-S1 29 M 56 L2-3 II L2-3 Rt. L2-3 ( ) L M 65 L4-5 I ( ) ( ) ( ) L F 64 L3-4 II L3-5 ( ) ( ) L F 61 L4-S1 I, I L4-S1 Both L4-S1 (þ) L4-S1 33 F 59 L2-3 II L2-3 ( ) ( ) L2-4 Spine E1023

3 Figure 1. A, The author s grading of destruction in the vertebral body. The MR images show grade II (B) and III (C) destruction of the body. reliability of the proposed new classification, Kendall coefficient of concordance was used to qualify the intraobserver and interobserver agreement by two spine specialists, who were independent of this study. The intraobserver and interobserver reliability showed good to excellent agreement ( , , respectively). To determine the validity, Spearman correlation between the scale according to the extent of vertebral body destruction and the preoperative Cobb angle of inflamed segment was calculated showing a positive correlation (r ¼ 0.659, P ¼ 0.01). Epidural Abscess Epidural abscess was observed in 29 among 33 patients (Figure 2 (A B)). In most patients, it was seen within the infected segment (one disc and two adjacent bodies). However, six patients had farther extension of epidural abscess over adjacent, intact disc. Psoas Abscess Psoas abscess was identified in 23 patients. Among which 16 patients had psoas abscess within the infected segment (bilateral in five and unilateral in 11). The other seven patients had psoas abscess extending beyond intact disc (bilateral in three patients and unilateral in four patients). METHODS Surgical Procedures At first, autogenic cancellous bone as large amount as possible was obtained from unilateral posterior superior iliac spine and stored in a bowl mixed with appropriate antibiotics. Via conventional posterior approach, subtotal laminectomy and discectomy were done like ordinary posterior lumbar interbody fusion (PLIF) procedure. All of the identifiable infected tissues were extirpated with curette and forceps mainly. The epidural abscess was drained using a thin suction tip. Drainage of the psoas abscess was performed by opening the outer fibrous ring of the intervertebral disc with a right-angled hemostat. After those procedures, posterior instrument was fixed in the lordotic position. Previously obtained cancellous autograft mixed with selective antibiotic based on culture studies or empirical choice (gentamicin and cefazolin) for culturenegative was packed into the intervertebral space. Figure 2. Case 13: Imaging studies obtained in a 53-year-old man with pyogenic spondylitis of the L2 3 intervertebral disc space. A, Preoperative radiographs reveal definite bony destruction on L2 and L3. B, Preoperative MR imaging shows grade III destruction of the body, epidural abscess in T2 weight sagittal image, right psoas abscess, and involvement of posterior column in axial image. E September 2016

4 In 14 of the 33 patients, the only infected segment was included in the fixation. In 19 patients, fixation from one or two levels above or below the affected vertebrae was carried out either because an epidural abscess extended beyond the infected segment requiring extensive laminectomy or intervertebral body destruction was too severe to be treated with screw fixation of the affected vertebrae alone. Spinal instrumentation systems applied were Diapason and Xia Spine (Stryker Spine, Cestus, France) in 21 patients and seven patients respectively, and Click X (Synthes-Dupey Spine, Kirkel, Germany) in remaining five patients. All of those were made of Ti6AI4 V alloy having the same biomechanical properties that is, in terms of antibiotic effectiveness, bacterial adherence, and glycocalyx formation. Two pairs of 400 ml evacuator with No. 15 F PVC drainage tubes (four in total) were utilized for the drainage of the intervertebral disc space abscess and epidural abscess. When daily amount of drainage diminishes into below 10 cc for more than two consecutive days, the drainage catheters were gradually pulled out and removed over several days. According to the antibiotic sensitivity of the bacteria, appropriate antibiotics were injected intravenously. According to the ESR and CRP, antibiotic therapy period was determined. In patients causative bacteria were not identified, two of the general antibiotics, cephalosporin and gentamicin, were prescribed. From postoperative second or third day, custom-made rigid thoracic lumbar sacral orthosis (TLSO) brace for thoracolumbar and lumbar sacral orthosis (LSO) for lumbar spine infections were applied for 6 weeks; strictly for the first 3 weeks, thereafter temporary disuse during sleeping time was allowed. between two lines drawn to the superior endplate of the superior vertebral body and the inferior endplate of the inferior vertebral body, was used to assess the sagittal alignment. Fusion Fusion was assessed based on the presence of bridging trabeculae between the bone graft and the adjacent vertebral bodies on the lateral views by two radiologists who were independent of surgeries. Statistical Analysis All data normality was determined with a Kolmogorov- Smirnov test. Paired t test was used to compare the changes in pre- and postoperative ESR and CRP values. Linear mixed model was applied (i) to analyze the sagittal alignment of fixed segment in terms of preoperative, immediate postoperative, and final follow-up state and (ii) to compare the difference between those of the ISFG in the 14 patients and the SSFG in the 19 patients. The null hypothesis was that neither correction loss in sagittal alignment for preoperative state compared with those for last follow up nor difference between the two groups would be shown. The differences in the mean times taken for the ESR and CRP to become normal and ambulation start day in an orthosis between the patients with and without an epidural abscess or psoas abscess were analyzed respectively using the Mann- Whitney U test. The level of significance was set at P < RESULTS Clinical Results Assessment Clinical Assessment Infection Control The ESR and CRP values obtained during admission and outpatient visits after surgery were used as an indicator of infection control. Rehabilitation and Complications Initiation date of ambulation after surgery and occurrence of postoperative complications were reviewed. Radiological Assessment Sagittal Alignment Changes in sagittal alignment of the fixed segment were measured on the lateral plain radiographs before surgery, immediately after surgery, and at the last follow up. In 14 patients in which inflamed segment are the same with fixed segment (inflamed segment fixation group, ISFG), the alignment of inflamed segment was assessed. In 19 patients in which required fixation of additional segment, the alignment of the spanned fixed segment was measured (spanned segment fixation group, SSFG). The Cobb angle, the angle Bacterial Identification and Antibiotic Treatment Causative microorganism was identified in 17 patients, whereas in the other 16 patients, no causative bacteria were identified (Table 2). The IV antibiotics were administered for a mean of 33.9 days (4.8 weeks) after surgery (range, days). Oral antibiotics were not routinely utilized after intravenous antibiotics, however in some patients with delayed normalization time of ESR and CRP, oral antibiotics course followed IV antibiotics for 4 to 6 weeks according to guidance of the infectious disease consultant. ESR and CRP The mean time taken for the ESR to become normal was 69.4 days (range, days, P < 0.01), almost times times longer than that for the CRP, 25.4 days (range, days, P < 0.01). With regard to the presence or absence of epidural abscess, psoas abscess, there was no statistically significant difference in the mean times taken for the ESR and CRP to become normal respectively (P > 0.05). Drainage Total drainage volume was on average 580 cc (range, cc). The period of indwelling drainage was mean 15.8 days (range, 6 32 days). Daily drainage volume decreased Spine E1025

5 TABLE 2. Factors About Infection Control No Organism Initial ESR (mm/hr) Normal ESR (day) Initial CRP (mg/dl) Normal CRP (day) Amount of H/V Insertion day of H/V 1 MSSA ( ) Enterobacter Staphylococcus UTI epidermidis 5 ( ) ( ) MRSA ( ) S. agalactiae MRSA MRSA S.epidermidis ( ) ( ) MRSA ( ) ( ) MRSA ( ) S.epidermidis ( ) MRSA MRSA ( ) ( ) MRSA ( ) ( ) ( ) S.epidermidis MRSA ( ) MRSA H/V indicates hemo-vac; MRSA, methicillin-resistant Staphylococcus Aureus; MSSA, methicillin-susceptible Staphylococcus Aureus; UTI, urinary tract infection. gradually but more than 30 cc was maintained for mean 4.5 days (range, 2 10 days). Ambulation and Complications Ambulation in an orthosis was started at a mean of 5.8 postoperative days (range, 2 19 days). There was no statistically significant in ambulation start day between patients with epidural abscess or not, and psoas abscess or not respectively (P > 0.05). No recurrence of infection or occurrence of complications such as instrument breakage was noted. Radiological Results Fusion Bridging of the trabeculae between the adjacent vertebral bodies across the graft bone that had been packed into the infected disc space was identified on the radiographs at a mean of 5.4 postoperative months in all the patients. Sagittal Alignment Regarding changes in the inflamed segment fixation group (ISFG), the mean amount of Cobb angle correction was 4.18; from of lordosis on average (range, 158 of kyphosis to 228 of lordosis) preoperatively to of lordosis on average (range, 58 of kyphosis to 308 of lordosis) immediately after surgery. Thereafter, the mean Cobb angle changed by 5.48 to kyphosis; of lordosis (range, 88 of kyphosis to 228 of lordosis) at the last follow-up. Totally, there was no significant difference between the preoperative and final results (P ¼ 0.11). Regarding the changes of those in the SSFG, the Cobb angle was improved from preoperative mean 6.98 of lordosis (range, of kyphosis to of lordosis) to of E September 2016

6 Figure 3. Lateral radiographs of a patient with spondylodiscitis in L2 L3 showing development of sagittal alignment after posterior instrumentation to one level above and below the affected vertebrae. A, Preoperative Cobb angle of inflamed segement. B, Postoperative Cobb angle of spanned fixed segment revealing restoration of lordosis. C, Cobb angle at the last follow-up showing maintanence of the lordotic alignment despite 1.98 of loss of correction. lordosis (range, 7.48 of kyphosis to 288 of lordosis) just after surgery. However, gradual loss of correction to kyphosis occurred afterwards and the result was 4.78 of lordosis (range, of kyphosis to 228 of lordosis) (Figure 3 (A C)). There was no statistic difference between the preoperative and final results (P ¼ 0.24). The mean Cobb angle change from before surgery to the last follow up was 1.38 of kyphosis for the ISFG and 2.28 of kyphosis for the SSFG, however did not show significant difference (P ¼ 0.26) and the two groups had similar tendency with their changes from the preoperative, postoperative, and to the last follow-up. Lordosis increased after the fixation then decreased gradually, but maintained the at least preoperative state at the last follow up (Figure 4). In the nine patients, including Grade III destruction, corresponded to SSFG, mean Cobb angle change from before surgery to the last follow-up was 5.48 of kyphosis although the difference was not significant (P ¼ 0.31). DISCUSSION Surgical treatment of spinal infection has developed in tandem with various approaches. Many authors reported that correction of kyphotic deformity was achieved and implant-related complications rarely occurred in the cases treated with anterior fusion combined with anterior instrumentation or posterior instrumentation. 2 9 Recently, various authors obtained promising results with posterior instrumentation and fusion or even minimal invasive instrumentation without anterior debridement in infectious spondylitis and emphasized the importance of stabilization of a diseased segment and appropriate antibiotic therapy. Although various posterior approach through a single posterior incision have been described, to our best knowledge; however, there are few report concerning the clear indication of posterior only approach without anterior procedures in regards to extent of vertebral body destruction, presence and extension of epidural abscess, psoas abscess. Furthermore, we found no report on whether long instrumentation to the uncontaminated level, where screws were not placed in the infected vertebrae could provide better results in terms of infection control, correction, and maintenance of kyphotic correction than instrumentation at the inflamed segment directly where there were the risk of the chance of spreading the infection and loss of correction. Even in patients with epidural abscess, psoas abscess, our approach showed good results in terms of hematological and clinical values. Prolonged drainage of remained abscess using suction drainage tubes and massive debridement of epidural space, psoas muscle may be an effective treatment strategy to decompress the epidural space and prevent the infected-related secondary process. 15,19 Few reports have discussed evaluating the change of sagittal alignment with posterior instrumentation only and our result is comparable with those in other reports including combined anterior and posterior approach. 9,16,20,21 Lee et al 20 reported that maintenance of kyphosis correction with only 1.88 of kyphotic angle loss at the final follow up from the postoperative state could be obtained (through posterior lumbar interbody Spine E1027

7 Figure 4. Devleopment of sagittal alignment. Mean Cobb angle at the last follow up shows difference of 1.38 compared with preoperative angle in the inflamed segment fixation group (ISFG). Sagittal alignment of spanned segment fixation group (SSFG) shows similar pattern. No significant difference of change was seen between two groups (P ¼ 0.26). fusion and pedicle screw fixation in pyogenic discitis). Although the operative technique we used in this study was similar to theirs, loss of kyphosis correction at the last follow up was more common (5.48 of Cobb angle loss) in our study cohorts. We attributed this to the fact that (1) the measuring methods were different; lordotic angle was measured from the upper end-plate of T12 to the upper end-plate of S1 in their study, and from upper endplate of the superior vertebral body and the lower endplate of the inferior vertebral body at fixed segment in our study; (2) the sites of infection were all in singlelevel and lower lumbar vertebra in their series but a total of 8 of 31 our patients were infected in the multilevels and a total of seven thoracolumbar junction and upper lumbar areas were affected; (3) there were more patients with advanced vertebral body destruction than those with discitis (Grade I according to our classification in our study); (4) a pedicle screw was not applied directly to the infected vertebral body, therefore, longer and more stable fixation would be achieved in their study than our study where pedicle screw was inserted including inflamed segment. However, there was no statistic difference between the preoperative and final results of sagittal alignment in the presence series and most of all, our approach demonstrated the successful fusion and complete recovery without recurrence of infection even in severe patients despite loss of kyphotic angle correction. We felt that short instrumentation including the inflamed segment could provide enough stability needed for controlling the infection and screws placed in the inflamed vertebrae may not spread the infection. However, in the patients with extent of the vertebral body destruction was more than 1/3 and less than 2/3 of body height (Grade III), in which loss of degree of kyphosis correction from before the surgery to the last follow up tended to be higher than those in lower grade, longer fixation more than 2 levels above and below the lesion would be needed. When body destruction was more severe (Grade IV), as other articles suggested, fixation with sparing the lesion or a combined anterior and posterior approach with autologous bone graft or titanium mesh cage also would provide stronger stability for restoration and maintenance of the kyphotic correction. 2 9,12,13,21,22 With regard to risk that the implant would be an obstacle on infection treatment, the adhesive strength and formation of a biofilm by bacteria could be subdued with preoperative antibiotic therapy and the occurrence of inflammation could be prevented by necrosis debridement thoroughly before the insertion of an instrument. 20,23 25 Continuous use of drainage and antibiotics before the formation of a biofilm by bacteria would block their growth. In our opinion, proper use of antibiotics and suction drainage is essential for the treatment of anterior lesions via posterior approaches. CONCLUSION We believe that short instrumentation and catheter drainage with posterior only approach would be one of the effective methods that resulted in successful treatment of infection and stability to facilitate early mobilization. Key Points Posterior spinal instrumentation can afford great spinal stability enabling early ambulation. For pyogenic infections, instrumentation has not been applied in fear of aggravation of the infection. We managed pyogenic spondylitis via posterior approach using prolonged suction drainage and short instrumentation, achieving successful control of the infection, solid fusion, early ambulation, and maintenance of sagittal alignment. References 1. Kim YM, Won JH, Seo JB, et al. Pyogenic L4-5 spondylitis managed with percutaneous drainage followed by posterior lumbar interbody fusion: a case report. J Korean Soc Spine Surg 2001;8: Buyukbebeci O, Karakurum G, Guleç A, et al. Tuberculous osteomyelitis of the lumbosacral region: a spinal epidural abscess with presacral extension. Arch Orthop Trauma Surg 2004;124: Chen W-J, Wu C-C, Jung C-H, et al. Combined anterior and posterior surgeries in the treatment of spinal tuberculous spondylitis. Clin Orthop 2002;398: Kim D-J, Yun Y-H, Moon S-H, et al. Posterior instrumentation using compressive laminar hooks and anterior interbody arthrodesis for the treatment of tuberculosis of the lower lumbar spine. Spine 2004;29:E E September 2016

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