Removal of Spinal Instrumentation Is Not Required to Successfully Treat Postoperative Wound Infections in Most Cases.

INTRODUCTION: Controversy exists regarding whether spinal implants need to be removed to treat postoperative deep wound infections (DWIs). This retrospective study aimed to determine whether the removal or retention of implants impacts the successful treatment of a DWI after spine surgery. METHODS: Postoperative spine surgery patients presenting with signs of infection who underwent irrigation and debridement (I&D) at Twin Cities Spine Surgeons at Abbott Northwestern Hospital, Minnesota, USA, were studied. First, the persistence of infection when implants were retained or removed was assessed. Second, we analyzed the persistence of infection with respect to the number of I&D, the use of vacuum-assisted closure (VAC) treatment, pseudoarthrosis status, and functional outcomes. RESULTS: One hundred thirty-five patients were included. Treatment of infection with retention of implants occurred in 64% (87/135); of these, 7% (6/87) had a persistent infection. Of patients with implant removal (36%, 48/135), 6% (3/48) had a persistent infection. Thus, we observed no difference between treatment with implants present compared to implants removed (p = 1.0). Fifty of the 135 patients (37%) received I&D and primary wound closure, and 85 (63%) patients received I&D and VAC treatment. There was no statistical difference between primary wound closure and VAC treatment (p = 0.15) with respect to persistence. Repeat I&D with VAC (three or more times) had a significantly lower rate of recurrence than those with two I&Ds. Pseudoarthrosis and persistent infection were unrelated. At minimum one-year follow-up, achieving a minimum clinically important difference in functional outcome was independent of persistent infection status. CONCLUSION: Persistent infection was unrelated to the retention of implants. When VAC treatment was deemed necessary, more than two I&Ds resulted in a significantly better cure for infection. Those with a persistent infection were no more likely to exhibit pseudoarthrosis than those with no persistent infection. All patients showed improvement in functional outcomes at minimum one-year follow-up.

Choose Wisely: Surgical Selection of Candidates for Outpatient Anterior Cervical Surgery Based on Early Complications Among Inpatients.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are attractive targets for transition to the outpatient setting. We assessed the prevalence of rapid responses and major complications in the inpatient setting following 1 or 2-level ACDFs and CDAs. We evaluated factors that may place patients at greater risk for a rapid response or a postoperative complication. METHODS: This was an institutional review board-approved, retrospective cohort study of adults undergoing 1 or 2-level ACDF or CDA at 1 hospital over a 2-year period (2018 and 2019). Data on patient demographic characteristics, surgical procedures, and comorbidities were collected. Rapid response events were identified by hospital floor staff and involved acute changes in a patient's clinical condition. Complications were events that were life-threatening, required an intervention, or led to delayed hospital discharge. RESULTS: In this study, 1,040 patients were included: 888 underwent ACDF and 152 underwent CDA. Thirty-six patients (3.5%) experienced a rapid response event; 22% occurred >24 hours after extubation. Patients having a rapid response event had a significantly higher risk of developing a complication (risk ratio, 10; p < 0.01) and had a significantly longer hospital stay. Twenty-four patients (2.3%) experienced acute complications; 71% occurred >6 hours after extubation. Patients with a complication were older and more likely to be current or former smokers, have chronic obstructive pulmonary disease, have asthma, and have an American Society of Anesthesiologists (ASA) score of >2. The length of the surgical procedure was significantly longer in patients who developed a complication. All patients who developed dysphagia had a surgical procedure involving C4-C5 or more cephalad. Patients with a rapid response event or complication were more commonly undergoing revision surgical procedures. CONCLUSIONS: Rapid response and complications are uncommon following 1 or 2-level ACDFs or CDAs but portend a longer hospital stay and increased morbidity. Revision surgical procedures place patients at higher risk for rapid responses and complications. Additionally, older patients, patients with chronic obstructive pulmonary disease or asthma, patients who are current or former smokers, and patients who have an ASA score of ≥3 are at increased risk for postoperative complications. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Symptomatic pseudarthrosis requiring revision surgery after 1- or 2-level ACDF with plating: peek versus allograft.

BACKGROUND: Polyetheretherketone (PEEK) and machined allograft interbody spacers are among devices used as fusion adjuncts in anterior cervical discectomy and fusion (ACDF). Most results are good to excellent but some patients develop pseudarthrosis. We compared the reoperation rates for pseudarthrosis following 1- or 2-level ACDF with PEEK or allograft cages. METHODS: This was a retrospective cohort study. We reviewed patients who underwent 1- or 2-level ACDF. The rate of subsequent surgery for pseudarthrosis was calculated for cases confirmed by computerized tomography. Patient-reported outcomes were collected at post-index surgery follow-up and post-revision ACDF follow-up. Radiographic parameters were assessed at a minimum of 1-year post-op on all patients. RESULTS: Two hundred and nine patients were included: 167 received allograft and 42 received PEEK. Subsidence was demonstrated in 31% of allograft and 29% of PEEK patients. There were no significant differences in clinical outcomes between allograft and PEEK groups. Clinical outcomes were not adversely affected by subsidence. Reoperation for pseudarthrosis was performed in 8% of allograft patients and 14% of PEEK patients (not statistically different). Improvement in patient-reported outcome was significantly better for patients without symptomatic post-operative pseudarthrosis. CONCLUSIONS: Both allograft and PEEK spacers are acceptable options for ACDF surgery. Similar clinical outcomes and rates of radiographic subsidence were found. Subsidence was not a factor in clinical outcomes. Reoperation for pseudarthrosis was associated with poor outcomes. A higher incidence of revision for symptomatic pseudarthrosis occurred in the PEEK group, but this was not statistically significant.

Complications with Minimally Invasive Transforaminal Lumbar Interbody Fusion for Degenerative Spondylolisthesis in the Obese Population.

STUDY DESIGN: A level-3 retrospective cohort analysis. OBJECTIVE: The aim of this study was to describe obesity's effect on complications and outcomes in degenerative spondylolisthesis patients treated by minimally invasive transforaminal lumbar interbody fusion (MI TLIF). SUMMARY OF BACKGROUND DATA: Obesity is associated with a greater complication rate among lumbar spine surgery patients. Poor clinical outcomes might likewise be supposed, but the association is not well established. Minimally invasive techniques have been developed to reduce complications and improve clinical outcomes in comparison to traditional open techniques. METHODS: We reviewed 134 consecutive patients with degenerative spondylolisthesis undergoing MI TLIF. Subjects were grouped into nonobese (N = 65) and obese (N = 69) cohorts. The obese group was further subdivided by BMI. Patient demographics, perioperative complications, and outcome scores were collected over a minimum of 24 months. Four periods (intraoperative, postoperative hospitalization, 6-month, and 24-month postoperative) were assessed. RESULTS: Cohort demographics were not significantly different, but it was noted that obese patients had more major comorbidities than nonobese patients. There was no difference in intraoperative complications between the two groups. The in-hospital complication rate was significantly greater in the obese group. The 6-month postoperative complication rate was not different between cohorts. Wound drainage was most common and noted only in the obese cohort. Complications at 24 months were not different but did trend toward significance in the obese for recurrence of symptoms and total complications. Functional outcome was better among nonobese subjects compared with obese subjects at every interval (significant at 6 and 12 months). Back pain scores were significantly better among nonobese subjects than obese subjects at 24 months, but Leg Pain scores were not different. CONCLUSIONS: MI TLIF can be safely performed in the obese population despite a higher in-hospital complication rate. Knowledge of common complications will help the treatment team appropriately manage obese patients with degenerative spondylolisthesis. LEVEL OF EVIDENCE: 3.

Posterolateral Versus Transforaminal Interbody L4/5 Fusion: Correlation With Subsequent Surgery.

STUDY DESIGN: This is a retrospective cohort study. OBJECTIVE: To compare posterolateral versus transforaminal interbody fusion (PLF vs. PLF+TLIF) of the L4/5 segment regarding rates of subsequent surgery, clinical and radiographic parameters, and patient satisfaction. SUMMARY OF BACKGROUND DATA: Surgical treatment of lumbar stenosis, decompression with or without fusion, is an efficacious treatment in select patients. Reoperation is thought to be a problem after lumbar fusion. Despite multiple studies, the fusion method that minimizes the need for subsequent surgery has yet to be determined. MATERIALS AND METHODS: A retrospective cohort study was conducted on 89 patients who had an isolated L4/5 decompression and fusion, from January 2006 to 2012. All patients had stenosis and degenerative spondylolisthesis at the L4/5 level. All surgeries were performed at a single center, using either PLF (31 patients) or PLF+TLIF (58 patients) techniques. Preoperative and postoperative patient-reported outcome measures (Oswestry disability index, visual analog scale back pain, visual analog scale leg pain) and radiographic parameters (L4/5 lordosis and overall lumbar lordosis) were measured. Patient satisfaction was acquired via a questionnaire. Chart reviews and patient questionnaires were used to determine the incidence of subsequent lumbar surgery over a minimum follow-up of 5 years. RESULTS: At an average of 8.7 years follow-up, 2 of 31 patients in the PLF group had subsequent lumbar surgery, compared with 16 of 58 patients in the PLF+TLIF group (6% vs. 28%; P=0.02). There were no significant differences between groups with respect to sex, age, body mass index, tobacco, perioperative measures, patient-reported outcomes, or radiographic parameters (P>0.05). CONCLUSIONS: Both PLF and PLF+TLIF are effective fusion methods for L4/5 stenosis and spondylolisthesis. In this study, patients treated with PLF were less likely to undergo a subsequent lumbar surgery. More research is needed to determine which factors influence whether PLF or PLF+TLIF should be used in these patients. LEVEL OF EVIDENCE: Level III.

Clinical and Radiologic Comparison of Minimally Invasive Surgery With Traditional Open Transforaminal Lumbar Interbody Fusion: A Review of 452 Patients From a Single Center.

STUDY DESIGN: Retrospective analysis of prospective data for parallel, consecutive series of patients (Level III). OBJECTIVE: Compare clinical results and radiographic outcomes of minimally invasive surgery (MIS) versus open techniques for transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: Minimally invasive techniques allow transforaminal exposure with decreased soft tissue disruption, but the question remains whether surgical and functional outcomes are equivalent to open techniques. MATERIALS AND METHODS: A consecutive series of 452 1 or 2-level TLIF patients at a single institution between 2002 and 2008 were analyzed. A total of 148 were MIS patients and 304 were open. Operative time, estimated blood loss, infection rate, and hospital length of stay were recorded. Oswestry disability index (ODI) and visual analog (VAS) pain scores were documented preoperatively and postoperatively. Fusion was assessed radiologically at a minimum of 1 year follow-up. RESULTS: There were proportionally more 2-level than 1-level procedures in the open group compared with the MIS group; there were more Workers' Compensation patients among 1-level procedures than 2-level. There were more Spondylolisthesis patients and fewer Degenerative Disk Disease patients among one-level procedures compared with 2-level. Blood loss and operative time were lower in the MIS group. Length of hospital stay in the MIS cohort was shorter compared with the open cohort. There were 3 deep wound infections in the open cohort. ODI and VAS (leg and back) scores improved in both groups at 1 year compared with preoperative scores and did not differ between MIS and open cohorts. Fusion rate was similar for both groups (91% overall). One-level procedures and BMP use were associated with higher fusion rate, regardless of approach. CONCLUSIONS: MIS TLIF produces comparable clinical and radiologic outcomes to open TLIF with the benefits of decreased intraoperative blood losses, shorter operative times, shorter hospital stays, and fewer deep wound infections.

Posterior cervical lateral mass screw fixation and fusion to treat pseudarthrosis of anterior cervical fusion.

STUDY DESIGN: Retrospective clinical cohort study. OBJECTIVE: To determine the efficacy of posterior lateral mass screw/rod fixation and fusion for the treatment of symptomatic pseudarthrosis of anterior cervical fusion. SUMMARY OF BACKGROUND DATA: Both anterior revision and posterior repair of cervical pseudarthrosis have been reported. To date, there is still debate in the literature as how the patient with symptomatic cervical pseudarthrosis should be addressed. METHODS: Thirty-eight consecutive patients with symptomatic anterior cervical pseudarthrosis were treated with posterior lateral mass screw/rod fixation and fusion. The average follow-up was 28 months (24 to 60 mo) and patients were assessed with clinical examination, questionnaires, flexion-extension lateral radiographs, and/or computed tomography scans. The clinical results were classified as excellent, good, fair, or poor, according to Zdeblick criteria. RESULTS: All patients achieved a solid radiographic fusion at the final follow-up. The result was excellent in 10 patients, good in 22, fair in 6, and poor in none. CONCLUSIONS: Patients with symptomatic cervical pseudarthrosis that develops after anterior cervical discectomy and fusion may be managed successfully with posterior lateral mass screw fixation and fusion.

A concomitant posterior approach improves fusion rates but not overall reoperation rates in multilevel cervical fusion for spondylosis.

STUDY DESIGN: Retrospective comparative study of 2 approaches to multilevel fusion for cervical spondylosis in consecutive patients at a single institution. OBJECTIVE: To provide justification for a concomitant posterior approach in multilevel cervical fusion for spondylosis by demonstrating decreased pseudarthrosis and reoperation rates. SUMMARY OF BACKGROUND DATA: Among the factors that affect cervical rates is the number of levels, such that increasing the number of levels leads to lower fusion rates. Because of this, modifications have been sought to improve union in multilevel procedures. One option is an antero-posterior (AP) approach or circumferential arthrodesis. METHODS: Seventy-eight consecutive patients who underwent multilevel cervical fusion at a single institution and with minimum 2-year follow-up data were divided into an anterior-only group (anterior: n=55), and an AP group (AP: n=23). Union was assessed by surgical exploration, computerized tomography scan, and flexion-extension radiographs. The groups were compared in terms of pseudarthrosis rates and reoperation rates. RESULTS: Using chi(2) analysis, there was a significant difference in pseudarthrosis rates (anterior 38% vs. AP 0%; P<0.001), and reoperation rate for pseudarthrosis (anterior 22% vs. AP 0%; P=0.01). There were no differences in overall (anterior 36% vs. AP 30%; P=0.62) and early (anterior 15% vs. AP 26%; P=0.13) reoperation rates, but late reoperations were increased in the anterior group (24% vs. AP 4%; P=0.043). CONCLUSIONS: A concomitant posterior fusion significantly reduced the incidence of pseudarthrosis (0% vs. 38%) and pseudarthrosis-related reoperations (0% vs. 22%) compared with traditional anterior-only fusion. However, this did not translate to a difference in overall reoperation rates. The majority of reoperations in the AP group (86%) were performed within 6 months, whereas those in the anterior-only group (65%) were performed later, which was generally when a pseudarthrosis became evident.

Cervical degenerative index: a new quantitative radiographic scoring system for cervical spondylosis with interobserver and intraobserver reliability testing.

BACKGROUND: The lack of a widely available scoring system for cervical degenerative spondylosis encouraged the authors to establish and validate a systematic quantitative radiographic index. MATERIALS AND METHODS: This study included intraobserver and interobserver reliability testing among three reviewers with different years of experience. Each observer independently scored four cervical radiographs of 48 patients at separate intervals, and statistical analysis of the grading was performed. RESULTS: There was high intraobserver and interobserver reliability between the two experienced observers. There was fair reliability between the less experienced observer and the more experienced observers. CONCLUSIONS: The cervical degenerative index appears to be a reliable and reproducible radiographic assessment of cervical spondylosis. The index will have direct applicability for longitudinal study of cervical spondylosis and may be clinically relevant as well.

Cervical degenerative changes in idiopathic scoliosis patients who underwent long fusion to the sacrum as adults: incidence, severity, and evolution.

BACKGROUND: To date, there have been no published studies of the degenerative changes in the cervical spine in adult idiopathic scoliosis patients with thoracic and lumbar curves severe enough to require major reconstructive surgery. MATERIALS AND METHODS: The primary study group was 48 adult patients who had previously undergone a fusion from T10 or higher to the sacrum as an adult for idiopathic scoliosis. These were compared to 38 adults with unfused idiopathic scoliosis of 30 degrees -50 degrees and to 42 symptomatic adults presenting with cervical pain. Cervical degeneration was assessed using a new cervical degenerative index (CDI). RESULTS: The amount of degenerative change seen in the cervical spine in the long-fusion group was significantly higher at baseline (just prior to the fusion) than the two control populations and became much higher at a mean follow-up of 8.5 years. CONCLUSIONS: This unique subgroup of patients, those having fusion from the thoracic spine to the sacrum as adults for adolescent idiopathic scoliosis, had a high incidence and severity of degenerative changes in their cervical spine. Due to the presence of advanced cervical degenerative changes prior to the fusion, it is not possible to blame the fusion as the main cause for these findings. These changes are either related to the thoracic and lumbar deformities or are more likely due to this subgroup having a higher natural propensity for degenerative changes.

The use of bone morphogenetic protein in lumbar spine surgery.

Creating a solid lumbar spinal fusion remains a challenge. Despite advances in fixation, a pseudarthrosis still may occur. Recently, attention has focused on creating a more biologically favorable environment to enhance fusion rate. Bone morphogenetic proteins (BMPs) are a group of secreted growth factors that belong to the transforming growth factor-beta superfamily. Two recombinant BMP proteins, rhBMP-2 and rhBMP-7 (OP-1), have been used successfully in preclinical and clinical trials and are commercially available for clinical applications.

Clinical and radiological outcome of anterior-posterior fusion versus transforaminal lumbar interbody fusion for symptomatic disc degeneration: a retrospective comparative study of 133 patients.

Abundant data are available for direct anterior/posterior spine fusion (APF) and some for transforaminal lumbar interbody fusion (TLIF), but only few studies from one institution compares the two techniques. One-hundred and thirty-three patients were retrospectively analyzed, 68 having APF and 65 having TLIF. All patients had symptomatic disc degeneration of the lumbar spine. Only those with one or two-level surgeries were included. Clinical chart and radiologic reviews were done, fusion solidity assessed, and functional outcomes determined by pre- and postoperative SF-36 and postoperative Oswestry Disability Index (ODI), and a satisfaction questionnaire. The minimum follow-up was 24 months. The mean operating room time and hospital length of stay were less in the TLIF group. The blood loss was slightly less in the TLIF group (409 vs. 480 cc.). Intra-operative complications were higher in the APF group, mostly due to vein lacerations in the anterior retroperitoneal approach. Postoperative complications were higher in the TLIF group due to graft material extruding against the nerve root or wound drainage. The pseudarthrosis rate was statistically equal (APF 17.6% and TLIF 23.1%) and was higher than most published reports. Significant improvements were noted in both groups for the SF-36 questionnaires. The mean ODI scores at follow-up were 33.5 for the APF and 39.5 for the TLIF group. The patient satisfaction rate was equal for the two groups.

Perioperative complications in revision anterior lumbar spine surgery: incidence and risk factors.

STUDY DESIGN: This is a retrospective review of 129 consecutive anterior lumbar revision surgeries in 108 patients. It is a single-center, multi-surgeon study. OBJECTIVE: To determine occurrence rates and risk factors for perioperative complications in revision anterior lumbar fusion surgery. SUMMARY OF BACKGROUND DATA: Although complication rates from large series of primary anterior fusion procedures have been reported, reports of complication rates for revision anterior fusion procedures are relatively rare. Concern exists chiefly about the risk to vascular and visceral structures because of scar tissue formation from the original anterior exposure. METHODS: This was a retrospective review of 129 consecutive anterior revision lumbar surgeries in 108 patients operated between 1998 and 2003. There were 40 men and 68 women. The age of patients ranged from 25 to 83 (average 50.6 years). Patients were excluded if surgery was for tumor or infection. Patients were divided into 2 groups; those with revision surgery at the same level and those with revision surgery at an adjacent level. Outcome measures included all perioperative complications. Statistical analysis included Student t test and nonparametric sign-rank. RESULTS: The number of surgical levels treated for revision was similar between the 2 groups (1 level 69%; 2 levels 19%; 3 or more levels 12%). Revision cases at the same operative level had a higher overall complication rate (42%) compared with extensions (20%; P = 0.007). This difference was primarily because of vein lacerations (23.7% vs. 3.6%, P = 0.002). There were 2 ureteral problems, both successfully salvaged. There were no arterial injuries or deaths. CONCLUSION: Complication rates for revision lumbar surgery in this series were 3 to 5 times higher than reported for primary lumbar exposures. Complication rates were significantly higher for revision anterior lumbar fusions at the same segment, which were typically in the lower lumbar spine, compared with cases involving extensions, which were typically in the upper lumbar spine.

Revision lumbar arthrodesis for the treatment of lumbar cage pseudoarthrosis: complications.

STUDY DESIGN: A study documenting major complications encountered in revision procedures for lumbar cage pseudoarthrosis. OBJECTIVE: To document the perioperative complications associated with revision surgery for threaded cylindrical cage pseudoarthrosis. SUMMARY OF BACKGROUND DATA: Pseudoarthrosis after cylindrical cage placement manifests as persistent or recurrent pain and disability after surgery. Revision strategies include isolated posterior stabilization and posterior bone grafting, versus circumferential revision where an attempt is made to remove the cages anteriorly, followed by posterior stabilization and fusion. Potential complications associated with these revision procedures have not been adequately documented in the past. METHODS: Forty-seven consecutive patients with the diagnosis of cylindrical cage pseudoarthrosis were surgically treated with either a circumferential revision (AP) or an isolated posterior instrumented fusion (P). All intraoperative and postoperative complications were documented. Radiographic interbody fusion rates and preoperative and postoperative visual analog scale (VAS) scores were documented. RESULTS: Three of the AP patients, all with anterior cage placement at L5-S1, had iliac vein lacerations requiring repair. A fourth patient had a ureteral injury requiring subsequent nephrectomy. Three patients who underwent circumferential revision and 2 patients who had an isolated posterior procedure had postoperative complications, including 2 infections (1 AP and 1 P), 1 radiculopathy (P), and 2 patients with prolonged ileus (both AP). There was a statistically significant decrease in overall VAS scores postoperatively for the 2 groups using the paired t test (P<0.0001). There was no difference in either the preoperative (P=0.22) or 2-year postoperative (P=0.30) VAS scores between the AP and P groups [rank-sum (Mann-Whitney) t tests]. Interbody fusion was achieved in 79% (30 of 38 levels) in the AP group. The interbody fusion rate was 37% (8 of 22) for the P group. CONCLUSIONS: Circumferential revision including cage removal, structural allograft placement, and posterior stabilization is associated with increased perioperative complications. Although an anterior approach showed increased interbody fusion rates, this technique did not lead to more superior clinical outcomes based on VAS scores. It remains to be shown by larger prospective studies if there is a true difference in outcome between these 2 groups that will justify the increased perioperative morbidity associated with attempted cage removal.

Complications in long fusions to the sacrum for adult scoliosis: minimum five-year analysis of fifty patients.

STUDY DESIGN: A retrospective study of complications with minimal 5-year follow-up of 50 adults with scoliosis with fusion from T10 or higher to S1. OBJECTIVES: To document the perioperative and long-term complications and instrumentation problems, and to attempt to determine variables which may influence these problems. It is not a study of curve correction, balance, or functional outcome. SUMMARY OF BACKGROUND DATA: Several previous studies from this and other centers have shown a relatively high complication rate for this select group of patients. Various fusion techniques (anterior, posterior, autograft, allograft), various instrumentation techniques, and various immobilization techniques have created confusion as to the best methodology to employ. Minimal 2-year follow-ups have been standard, but longer follow-ups have shown additional problems. METHODS: The study cohort consisted of 50 adult patients from a single center who had undergone corrective scoliosis surgery from T10 or higher to the sacrum and who had at least a 5-year minimum follow-up. The mean age was 54 years (range, 18-72), and the mean follow-up was 9.7 years (range, 5-26). All radiographs, office charts, and hospital charts were combed by an independent investigator for complications, which were divided into major and minor, as well as early, intermediate and late. The curvature values and corrections were the subject of a different article, and were not included in this study. RESULTS: There were no deaths or spinal cord injuries. Six patients had nerve root complications, 4 of which totally recovered. Pseudarthrosis was seen in 24% of the patients, only 25% of which were detected within the 2-year follow-up period. Pseudarthrosis was most common at the lumbosacral level. There was no statistical difference in the pseudarthrosis rate between patients with sacral-only fixation versus iliac fixation. Painful implants requiring removal were noted in 11 of the 50 patients. CONCLUSION: Long fusions to the sacrum in adults with scoliosis continue to have a high complication rate. As compared to the original publications in the 1980s (Kostuik and Hall, Spine 1983;8:489-500; Balderston et al, Spine 1986;11:824-9) the more recent articles have shown a reduction, but not elimination of the pseudarthrosis problem using segmental instrumentation and anterior fusion of the lumbar spine coupled with structural interbody grafting at L4-L5 and L5-S1. Two-year follow-up is inadequate as pseudarthrosis and painful implants often are detected later. Only 3 of the 12 patients with pseudarthrosis were detected within the first 2 years after surgery.

Reliability and accuracy of fine-cut computed tomography scans to determine the status of anterior interbody fusions with metallic cages.

BACKGROUND CONTEXT: Computed tomography (CT) scan has been shown to be more accurate than radiographs in evaluating anterior interbody fusion but may still over-read the extent of fusion. PURPOSE: To assess the reliability and accuracy of fine-cut CT scans with reconstructions in evaluating anterior lumbar interbody fusion (ALIF) with metallic cages using surgical exploration as the reference standard. STUDY DESIGN: Accuracy of a diagnostic test referenced to the gold standard. PATIENT SAMPLE: A total of 49 patients and 69 surgical levels. OUTCOME MEASURES: Evaluation of fine-cut CT scans for evidence of fusion with subsequent surgical exploration as the reference standard. METHODS: Forty-nine patients who underwent ALIF with metallic cages over 69 levels, who had a fine-cut CT scan before revision were included. Five spine surgeons unaware of the findings on surgical exploration evaluated pre-revision CT scans, classified these as fused or not; and determined the presence of a "sentinel sign" and a "posterior sentinel sign." Kappa coefficients for interobserver reliability, sensitivity, and specificity to detect fusion were determined. RESULTS: There were 26 males and 23 females with a mean age of 43 years. There were 27 smokers. Average time from index to revision surgery was 22 months. Interobserver kappa for classification as fused or not was 0.25 with 70% to 97% sensitivity and 28% to 85% specificity. The interobserver kappa for the sentinel sign was 0.34 with 13% to 33% sensitivity and 77% to 92% specificity. The interobserver kappa for the posterior sentinel sign was 0.23 with 33% to 87% sensitivity and 56% to 90% specificity. CONCLUSIONS: Raters generally overstated fusion with low specificities across raters and low consensus specificity. Overall accuracy of the posterior sentinel sign (74%) was higher than the sentinel sign (61%). The low kappa value indicates fair reliability. In patients with metallic interbody devices, surgeons should be cautious about interpreting the findings on fine-cut CT scans whether using a general assessment of the fusion, the sentinel sign, or the posterior sentinel sign.

SF-36 PCS benefit-cost ratio of lumbar fusion comparison to other surgical interventions: a thought experiment.

STUDY DESIGN: A retrospective review of prospectively collected data. OBJECTIVES: To review systematically the SF-36 PCS outcomes of a large data set, including several randomized clinical trials for lumbar spine fusion at 1 and 2 years after surgery. We also present for comparison a review of typical changes in SF-36 PCS in other surgical interventions (total knee replacement, total hip replacement, and coronary artery bypass surgery) to define the average reimbursement costs per PCS improvement with each of these interventions. SUMMARY AND BACKGROUND DATA: Data from 11 prospective multicenter studies (9 Food and Drug Administration Investigational Device Exemption, Randomized Prospective Clinical Trials, class 1 data) accounted for the lumbar spine fusion group (n = 1826). Data for total knee replacement, total hip replacement, and coronary artery bypass surgery were obtained from a comprehensive review of the literature. METHODS: Comparisons of SF-36 PCS improvements were made at defined postoperative time points and with published study findings of other medical conditions. Reimbursement estimates (not including estimated physician and rehabilitation fees) for each surgical intervention were based on Centers for Medicare and Medicaid Services Medicare Provider Analysis and Review and All Payer Data (2002). Cost estimates were calculated for a minimal clinical important improvement (reimbursement dollars/mean PCS change *5.42 point PCS improvement). RESULTS: SF-36 PCS significantly improved at both 1 and 2 years following lumbar spine fusion surgery (P < 0.0001), and was comparable to the control surgical outcomes. With the use of data from Centers for Medicare and Medicaid Services Medicare Provider Analysis and Review and All Payer Data, hospital reimbursement averaged $15.2-18.2K for lumbar spine fusion, $9.8-11.3K for total knee replacement, $9.6-11.3K for total hip replacement, and $9.8-11.3K for coronary artery bypass surgery. Calculations of reimbursement dollars to elicit minimum clinically important change in PCS of 5.42 points following surgery ranged from $6.1 to $7.3K for lumbar spine fusion, $5.7 to $6.6K for total knee arthroplasty, $3.9 to $4.5K for total hip replacement, and $18.2 to $22.5K for coronary artery bypass surgery. CONCLUSION: While the exact numbers may vary for each treatment based on the population studied and the cost estimates used, lumbar fusion cost per benefit achieved was very comparable to other well-accepted medical interventions (total hip replacement, total knee replacement, and coronary artery bypass surgery).

Stepwise methodology for plain radiographic assessment of pedicle screw placement: a comparison with computed tomography.

OBJECTIVE: The objective of this study is to evaluate the effectiveness of a specific methodology for plain radiographic assessment of lumbar pedicle screw position. PURPOSE: To evaluate the effectiveness of using orthogonal plain radiographs and a systematic method of interpretation, developed by the senior author, in assessing the placement of lumbar and lumbosacral pedicle screws. STUDY DESIGN: This was an adult cadaver study of the accuracy of using plain radiographs or computed tomography to assess pedicle screw position. Plain radiographs were performed and compared with computed tomography (CT) scans. Gross anatomic dissections were performed to directly confirm screw position. Variables, including screw material, radiographic view, and screw dimensions, were assessed for their effect on the ability of physicians to determine pedicle screw position. Multiple readers were included in the study, including 1 spine Fellow, 3 experienced orthopedic spine surgeons, and 1 neuroradiologist. METHODS: Five adult cadaveric spines were instrumented with titanium pedicle screws from L1 to S1. Screws were placed outside the confines of the pedicle in all 4 quadrants or within the pedicle using a Latin-Square design. Each cadaver was imaged with orthogonal radiographs and high-resolution CT scans. The spines were then reimaged after the instrumentation was replaced with stainless steel screws placed in the identical position. Finally, each spine was dissected to assess the exact position of the screws. Images were read in a blinded fashion by 1 spine fellow, 2 staff surgeons, and a staff radiologist. The results were compared with the known screw positions at dissection. RESULTS: In total, 120 pedicle screws were placed, 44 (38%) outside the confines of the pedicle. Sensitivity, defined as the percent of the misplaced screws that were correctly identified, was similar across the 3 diagnostic tests, but markedly improved when all CT formats were considered together. Similarly, specificity, defined as the percent of screws correctly read as being placed within the pedicle, was independent of radiographic examination. Sensitivity of the radiographic technique was 70.1% and specificity was 83.0%, whereas sensitivity for CT scans was 84.7% and specificity was 89.7%. There was an observed association with anatomic level, with a consistently less accuracy in detecting screw position at L1 with plain x-ray (P=0.001). Additionally, correct position of stainless steel screws was more difficult to detect as compared with titanium (P=0.033) using either x-rays or CT. Other variables examined, such as screw length and screw diameter, did not have an effect on the ability to read the positioning. CONCLUSIONS: CT scans, often considered the "gold standard" for clinical assessment of pedicle screw placement, have limitations when validated with gross anatomical dissection. The described systematic method for evaluating pedicle screw placement using orthogonal plain radiographs attained accuracy comparable to high-resolution CT scans.

Minimally invasive transforaminal lumbar interbody fusion: indications, technique, and complications.

The authors provide an overview of the minimally invasive transforaminal lumbar interbody fusion (TLIF) procedure including indications, technique, and complications. This novel technique is a method of achieving circumferential lumbar fusion using a unilateral dorsal approach. Minimally invasive TLIF uses a tubular retractor that is inserted via a muscle-dilating exposure, thereby minimizing the approach-related morbidity. This procedure is ideal for refractory mechanical low-back and radicular pain associated with spondylolisthesis, degenerative disc disease, and recurrent disc herniation. The authors' clinical experience and review of the medical literature indicate that TLIF can be effectively and safely performed in a minimally invasive fashion.