After Anterior Lumbar Interbody Fusion Research Articles

Impact of gender on outcomes following single-level anterior lumbar interbody fusion

BackgroundThere have been a multitude of studies attempting to identify the relationship between gender and postoperative outcomes; however, few studies have examined how this relationship may affect outcomes after anterior lumbar interbody fusion (ALIF) surgery. We aim to better characterize the impact that self-reported gender may have on patient reported outcome measures (PROMs) and achievement rates of minimum clinically important difference (MCID) after ALIF. MethodsA retrospective database of a single spine surgeon was searched for patients who had undergone single-level ALIF. Indications for surgery including acute trauma, infection, or malignancy were excluded. The population was separated into cohorts by self-reported gender, female or male. PROMs were recorded and compared within groups to their preoperative baselines and between groups. MCID achievement rate was compared between groups. Results140 patients were identified for this study, with 68 patients self-identifying as female gender. The male gender cohort was found to have a significantly greater prevalence of hypertension (p = 0.018). Both cohorts showed significant improvement during at least one or more postoperative time points for each evaluated outcome measure (p ≤ 0.048, all). No significant difference in mean PROM scores was noted between cohorts at any time point for any measured outcome. The female gender cohort had significantly greater MCID achievement rates for visual acuity scale (VAS) back pain overall and at the 6-month time point (p ≤ 0.043, both). The female gender cohort also had significantly greater achievement of MCID at the 1-year time point for VAS leg pain (p = 0.017). ConclusionBoth female and male gender cohorts demonstrated significant improvement in all outcomes measured at one or more postoperative time points. Postoperative outcomes did not differ by gender. MCID achievement was more common in female patients. Female patients may experience more tangible clinical improvement after ALIF compared to male patients.

The Morphological Changes in Adjacent Segments Amongst Patients Receiving Anterior and Oblique Lumbar Interbody Fusion: A Retrospective Study.

Adjacent segment disease (ASD) is troublesome condition that has proved to be highly related to spinal malalignment after spinal surgery. Hence, we aimed to evaluate the morphological changes after anterior lumbar interbody fusion (ALIF) and oblique LIF (OLIF) to establish the differences between the two surgical methods in terms of possible ASD avoidance. Fifty patients, half of whom received ALIF while the other half received OLIF, were analyzed with image studies and functional outcomes during the pre-operative and post-operative periods, and 2 years after surgery. Image measurements obtained included spinal-pelvic parameters, index lordosis (IL), segmental lordosis (SL), anterior disc height (ADH), posterior disc height (PDH) and adjacent segment disc angle (ASDA). The ADH and PDH in the adjacent segment decreased in the two groups while OLIF showed greater decrease without radiological ASD noted at 2-year follow-up. Both groups showed an increase in IL after surgery while ALIF showed greater improvement. No statistical difference was identified in functional outcomes between LIFs. We suggest that both ALIF and OLIF can restore adequate lordosis and prevent ASD after surgery. However, it should be noted that patient selection remains crucial when making any decision involving which of the two methods to use.

Metal failure and nonunion at L5-S1 after long instrumented fusion distal to pelvis for adult spinal deformity: Anterior versus transforaminal interbody fusion.

Pseudoarthrosis and metal failure at L5-S1 following long fusion surgery for adult spinal deformity (ASD) remain major issues. Few studies report on which anterior column support technique is better in terms of achieving fusion and avoiding metal failures. Our study aimed to evaluate the fusion status and metal failure rate at L5-S1 after anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF). The study population included patients aged >50years who underwent surgery for ASD. Anterior column supports at L5-S1 using ALIF and TLIF were compared with ≥ 2-year follow-up. Fusion status on 2-year computed tomography (CT) scan, metal failure, visual analog scale (VAS), and Oswestry disability index (ODI) were evaluated. 98 patients were included in this study (53 ALIF group and 45 TLIF group). We achieved solid fusion on 2-year CT scans in 88.9% and 69.8% patients in the TLIF and ALIF group, respectively. Metal failure developed in nine (17.0%) and six (13.3%) patients in the ALIF and TLIF group, respectively. The most common failure type was unilateral L5-S1 rod fracture (7 and five patients in the ALIF and TLIF group, respectively). Only one patient with bilateral rod fractures in the ALIF group required revision surgery. There were no differences in the VAS and ODI scores at the last follow-up. TLIF showed a better fusion rate than ALIF at L5-S1 after long instrumented fusion for ASD. However, the capacity to restore sagittal parameters was greater in the ALIF group. There were no differences between the groups regarding metal failure rate, revision surgery, or clinical outcomes.

Factors Affecting Postoperative Length of Stay in Patients Undergoing Anterior Lumbar Interbody Fusion

With hospital leaders and policy makers increasingly seeking ways to improve resource use, there has been heightened interest in reducing hospital length of stay (LOS) and performing spine procedures on an outpatient basis. We aimed to determine which risk factors correlated with prolonged LOS after anterior lumbar interbody fusion (ALIF). Medical records for patients who underwent ALIF were retrospectively reviewed. Patients were divided into those who had extended (≥3 days) versus nonextended (<3 days) LOS, and patient demographics, medical comorbidities, and preoperative medications were analyzed. Univariate and multivariate regression were then used to determine preoperative risk factors for extended LOS. A total of 166 patients were included (mean age, 48.7 years). Medical comorbidities included hypertension (31.9%), diabetes (8.4%), and obesity (body mass index>30 kg/m2) (48.8%). LOS was not extended in 121 patients and extended in 45. Mean LOS was 2.2 days (95% confidence interval, 1.9-2.5). On multivariate logistic analysis, age ≥65 years (P= 0.001), preoperative benzodiazepine use (P= 0.014), 12-item Short Form mental component score (P= 0.008), estimated blood loss (P= 0.015), time to mobilization (P < 0.001), and total operative time (P= 0.020) were independent predictors for extended LOS. As attempts are made to perform more spine procedure in ambulatory surgical centers, strict patient selection criteria are all critical in making this possible. Our results suggest that age, preoperative benzodiazepine use, higher intraoperative blood loss, delayed mobilization, and lower 12-item Short Form mental component score were correlated with increased LOS. Therefore, inpatient ALIF may be more suitable for patients with these risk factors.

An unusual case of acute cholecystitis following anterior lumbar interbody fusion

Abstract Introduction: Acute acalculous cholecystitis is also likely to occur in critical systemic conditions, such as trauma, burns, and postoperative situations. Here, we report a rare case of acute cholecystitis after anterior lumbar interbody fusion (ALIF). Patient concerns: A 75-year-old female experienced low-grade fever (&lt; 38.3°C), following ALIF of L4–5. On postoperative day 3, the patient exhibited acute jaundice without abdominal discomfort. Diagnosis: Laboratory investigations revealed elevated values for liver function tests and bilirubin levels (aspartate aminotransferase, 79 IU/L; alanine aminotransferase, 56 IU/L; total bilirubin, 7.6 mg/dL; and direct bilirubin 4.1 mg/dL), with no prominent abnormalities, such as stones or dilatation of the hepatobiliary tract, on abdominal computed tomography. However, endoscopic ultrasound revealed diffuse thickening of the gallbladder (GB) wall and large amounts of echogenic material in the GB lumen, suggesting acute cholecystitis with GB sludge. Interventions: Emergency endoscopic retrograde cholangiopancreatography and biliary drainage were performed by inserting a single-tail catheter through the biliary tract. Outcomes: Clinical symptoms, including skin jaundice and icteric sclera, gradually improved, and the patient was discharged 13 days after the surgery. Liver function tests and bilirubin levels were normalized in the final laboratory investigations during the hospitalization period (aspartate aminotransferase. 26 IU/L; alanine aminotransferase. 16 IU/L; total bilirubin, 2.1 mg/dL; direct bilirubin, 0.9 mg/dL; and C-reactive protein, 0.21 mg/dL). Conclusion: Spinal surgeons should be aware of the possibility of biliary complications after ALIF. In particular, postoperative cholecystitis in elderly patients has a poor prognosis; therefore, early diagnosis and intervention are the only ways to improve the prognosis.

Does the ACS NSQIP Surgical Risk Calculator Accurately Predict Complications Rates After Anterior Lumbar Interbody Fusion Procedures?

Clinical case series. The aim of this study was to determine the effectiveness of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) surgical risk calculator in the prediction of complications after anterior lumbar interbody fusion (ALIF). Identifying at-risk patients may aid in the prevention of complications after spine procedures. The ACS NSQIP surgical risk calculator was developed to predict 30-day postoperative complications for a variety of operative procedures. Medical records of patients undergoing ALIF at our institution from 2009 to 2019 were retrospectively reviewed. Demographic and comorbidity variables were entered into the ACS NSQIP surgical risk calculator to generate percentage predictions for complication incidence within 30 days postoperatively. The observed incidences of these complications were also abstracted from the medical record. The predictive ability of the ACS NSQIP surgical risk calculator was assessed in comparison to the observed incidence of complications using area under the curve (AUC) analyses. Two hundred fifty-three (253) patients were analyzed. The ACS NSQIP surgical risk calculator was a fair predictor of discharge to non-home facility (AUC 0.71) and surgical site infection (AUC 0.70). The ACS NSQIP surgical risk calculator was a good predictor of acute kidney injury/progressive renal insufficiency (AUC 0.81). The ACS NSQIP surgical risk calculator was not an adequate predictive tool for any other category, including: pneumonia, urinary tract infections, venous thromboembolism, readmission, reoperations, and aggregate complications (AUC < 0.70). The ACS NSQIP surgical risk calculator is an adequate predictive tool for a subset of complications after ALIF including acute kidney injury/progressive renal insufficiency, surgical site infections, and discharge to non-home facilities. However, it is a poor predictor for all other complication groups. The reliability of the ACS NSQIP surgical risk calculator is limited, and further identification of models for risk stratification is necessary for patients undergoing ALIF.Level of Evidence: 3.

Predictors of the need for laminectomy after indirect decompression via initial anterior or lateral lumbar interbody fusion.

The goal of this study was to evaluate factors that are associated with the need for additional posterior direct decompressive surgery after anterior lumbar interbody fusion (ALIF) or lateral lumbar interbody fusion (LLIF). Eighty-six adult patients who underwent ALIF or LLIF for degenerative spondylolisthesis and foraminal stenosis were enrolled. Patient factors (age, sex, number of surgery levels, and visual analog scale [VAS] score for leg and back pain); procedure-related factors (cage height and lordosis); and radiographic measurements (disc height [DH]; foraminal height [FH], foraminal area [FA], central canal diameter [CCD], and facet joint degeneration [FD]) were analyzed. All patients underwent staged surgery on 2 different days, with the anterior portion first, followed by the posterior portion. Of 86 patients, 62 underwent posterior decompression and 24 had no posterior decompression. There were no significant differences between groups with regard to age, sex, preoperative VAS score for back pain, cage height, cage angulation, preoperative DH, FH, FA, CCD, and FD (p > 0.05). The group that underwent posterior decompression showed statistically different numbers of treated segments (1.92 vs 1.21, p < 0.01), preoperative VAS leg score (7.9 vs 6.3), symptom duration (14.2 months vs 9.4 months), postoperative DH improvement (61.3% vs 96.2%), postoperative FH improvement (21.5% vs 32.1%), postoperative FA improvement (24.1% vs 36.9%), and cage height minus preoperative DH (5.3 mm vs 7.5 mm) compared with the nondecompression group. There appears to be some correlation between the need for posterior decompression and the number of treated segments, VAS leg scores, symptom duration, FH, FA, and difference between the cage height and preoperative DH. In selected patients undergoing staged surgery, indirect decompression without direct decompression may be a reasonable option in treating degenerative spinal conditions.

Surgical Strategies for the Treatment of Lumbar Pseudarthrosis in Degenerative Spine Surgery: A Literature Review and Case Study.

Pseudarthrosis after lumbar fusion can generate pain and disability and often requires revision. However, results of revision procedures have historically been relatively poor. The aim of this review was to examine the current evidence related to the management of lumbar pseudarthrosis, with a focus on revision after failure of posterolateral fusion or lumbar interbody fusion. A review of orthopedic spine literature published before March 2019 was conducted using PubMed and Google Scholar. Studies addressing revision after failed posterolateral fusions and after failed interbody fusion were selected. We also present a case of successful revision after failed transforaminal lumbar interbody fusion (TLIF). The review revealed that persistent pseudarthrosis after revision posterolateral fusion occurs at rates of 35 to 51%. No significant difference has been demonstrated in rates of successful fusion after anterior lumbar interbody fusion (ALIF) and ALIF with revision posterolateral fusion for pseudarthroses after failed TLIF procedures (81% versus 88%), although ALIF alone may be appealing because it avoids further disruption of the posterior musculature. No significant differences have been observed in quality-of-life scores among patients undergoing revision after posterolateral fusion, TLIF, ALIF, or ALIF with posterior fusion. Failed TLIF cages may be extracted and replaced through an anterior or lateral approach. If the geometry of the failed cage permits insertion of a second cage, a contralateral approach may be used. Revision retroperitoneal approaches are associated with higher complication rates. The management of lumbar pseudarthrosis requires careful planning, as well as intra-operative attention to detail, for revision surgery to be successful. Circumferential procedures have shown success in revision posterolateral and interbody fusion failures.

Discharge to Inpatient Care Facility After Anterior Lumbar Interbody Fusion: Incidence, Predictors, and Postdischarge Outcomes

Despite a significant number of patients being discharged to inpatient care facilities after anterior lumbar interbody fusion (ALIF), the current literature remains limited regarding the predictors associated with a nonhome discharge and the impact of continued inpatient care in a facility on postdischarge outcomes. The 2013-2016 American College of Surgeons National Surgical Quality Improvement Program was queried using Current Procedural Terminology (CPT) codes for ALIF (CPT-22558) and additional level fusions (CPT-22585). Discharge to inpatient care facilities included discharge to skilled care facilities and/or inpatient rehabilitation units. Independent predictors of an inpatient care facility discharge were age older than 45 years (P < 0.001), female sex (P < 0.001), more than 10% body weight loss in the last 6 months prior to surgery (P=0.012), American Society of Anesthesiologists grade greater than II (P=0.005), undergoing a 2-level (P < 0.001) or more than 2-level fusion (P=0.017), a length of stay greater than 3 days (P < 0.001), and the occurrence of any predischarge complication (P < 0.001). After adjustment for differences in clinical and baseline characteristics between the 2 groups, discharge to an inpatient care facility after ALIF was independently associated with higher odds of any postdischarge complication (P=0.010), postdischarge wound complication (P=0.005), and postdischarge septic complications (P=0.011). No significant impact was seen on 30-day readmissions (P=0.943), 30-day reoperations (P=0.228), and 30-day mortality (P=0.913). With an increasing focus toward minimizing costs associated with postacute care, providers should understand the need of appropriate preoperative risk stratification and construction of care pathways aimed at a home discharge to reduce the occurrence and/or risk of experiencing postdischarge complications.

Effect of Smoking Status on Successful Arthrodesis, Clinical Outcome, and Complications After Anterior Lumbar Interbody Fusion (ALIF).

Anterior lumbar interbody fusion (ALIF) is a surgical technique indicated for the treatment of several lumbar pathologies. Smoking has been suggested as a possible cause of reduced fusion rates after ALIF, although the literature regarding the impact of smoking status on lumbar spine surgery is not well established. This study aims to assess the impact of perioperative smoking status on the rates of perioperative complications, fusion, and adverse clinical outcomes in patients undergoing ALIF surgery. A retrospective analysis was performed on a prospectively maintained database of 137 patients, all of whom underwent ALIF surgery by the same primary spine surgeon. Smoking status was defined by the presence of active smoking in the 2 weeks before the procedure. Outcome measures included fusion rates, surgical complications, Short-Form 12, and Oswestry Disability Index. Patients were separated into nonsmokers (n=114) and smokers (n= 23). Univariate analysis demonstrated that the percentage of patients with successful fusion differed significantly between the groups (69.6% vs. 85.1%, P= 0.006). Pseudarthrosis rates were shown to be significantly associated with perioperative smoking. Results for other postoperative complications and clinical outcomes were similar for both groups. On multivariate analysis, the rate of failed fusion was significantly greater for smokers than nonsmokers (odds ratio 37.10, P= 0.002). The rate of successful fusion after ALIF surgery was found to be significantly lower for smokers compared with nonsmokers. No significant association was found between smoking status and other perioperative complications or adverse clinical outcomes.

Influence of Obesity on Complications, Clinical Outcome, and Subsidence After Anterior Lumbar Interbody Fusion (ALIF): Prospective Observational Study.

The complications associated with obesity have been well described for posterior lumbar spinal surgery. However, the influence of obesity on anterior lumbar interbody fusion (ALIF) is not well established. We aimed to compare complication risks, functional outcomes, and subsidence rates in normal-weight, overweight, and obese patients who underwent ALIF. A total of 137 consecutive patients undergoing ALIF surgery from 2012 to 2014 were followed prospectively. Patients were categorized into 3 groups according to their body mass index (BMI). Patients were evaluated preoperative and postoperatively. Outcome measures included Short Form-12, Oswestry Disability Index, surgical complications, and subsidence. There was no significant difference between the BMI groups in terms of baseline age, proportion of men, levels operated, smoking status, diabetes status, or anterior, posterior, or average disc height. There was no difference in operative duration, blood loss, or hospital stay. At 12-month follow-up, no difference was found in terms of total complications, change in Short Form-12 mental or physical component scores, or Oswestry Disability Index scores. Average disc height was significant lower for the obese group (11.3 mm) compared with the normal-weight (14.4 mm) group. Fusion rate was also significantly lower for patients who were obese (60%) compared with normal-weight (88.2%) and overweight patients (76%) (P= 0.014). Delayed subsidence rates also were similar between normal-weight and overweight patients. There were no differences in functional outcomes or complications in patients with elevated BMI compared with normal-weight patients. Fusion rates were lower for patients were obese. Obesity should not be considered a contraindication to surgery in patients with appropriate indication to undergo ALIF.

Bone union rate with recombinant human bone morphogenic protein-2 versus autologous iliac bone in PEEK cages for anterior lumbar interbody fusion

Autologous iliac crest bone graft (ICBG) is the gold standard material for spinal fusion. Bone graft substitutes, such as recombinant human bone morphogenic protein 2 (rhBMP-2) have been developed to promote spinal fusion and address morbidity issues related to ICBG harvesting. The objective of this study was to compare bone fusion rates after anterior lumbar interbody fusion (ALIF) between ICBG and rhBMP-2 by examining thin-cut computed tomography (CT) images at the one year follow-up. Fifty one patients (62 levels) who underwent single- or two-level ALIF via the video-assisted minimally invasive anterior approach in our institution were assessed. Radiolucent cages were inserted in all cases. Each cage has a middle beam delimiting two chambers. Grafting was performed as follows: one chamber was filled with autologous ICBG, and the other chamber was filled with 6 mg of rhBMP-2. Thin-cut CT-scan multiplanar reconstruction analyses were performed to assess the rate and quality of bone fusion at one year of follow-up. Fusion was observed in 55 levels (88.7 %), with significant differences in fusion rates with rhBMP-2 and ICBG (71 % vs. 88.7 %) (P=0.001). Osteogenesis in the rhBMP-2 chamber had a centripetal pattern in all cases, leaving a central void in 97.7 % of cases representing 38.3 % of the surface of its chamber (range 0-80.3 %). In ICBG chambers, graft resorption was present in 44.4 %, representing 9.8 % of the chamber surface (range 0-52.2 %). RhBMP-2 was inferior to ICBG in terms of rate and quality of bone fusion in one- or two-level ALIF.

Incidence and Outcome of Graft Resorption in Anterior Lumbar Interbody Fusion

Retrospective cohort. To determine the incidence of resorption after anterior lumbar interbody fusion (ALIF) and its effect on outcome. Recombinant human bone morphogenetic protein-2 (rhBMP-2) used in ALIF has been associated with a 0.5% to 82% incidence of resorption. This has been described as either a complication or part of the natural history. We postulate that early resorption (≤4 mo) in ALIF using femoral ring allograft augmented with rhBMP-2 supplemented with posterior instrumentation has no effect on outcome. Institutional review board-approved retrospective 60 chart cohort study of ALIF using femoral ring allograft-augmented rhBMP-2 supplemented with posterior instrumentation from May 5, 2005, to April 6, 2010. Two groups were based upon the presence or absence of early graft resorption (≤4 mo). Patients were seen prior to surgery and postoperatively until 29 ± 20 months (last visit). Follow-up visual analogue scale pain scores and radiographical evidence of fusion were measured and compared between the 2 groups. Sixty patients, 27 females and 33 males had follow-up for 29 ± 20 months. Group 1 (33 patients, 45 levels) and group 2 (27 patients, 36 levels) were identical in age (P = 0.62), sex distribution (P = 0.43), preoperative pain score (P = 0.63), and in the rhBMP-2 dose per level (P = 0.77). There were no significant group differences in postoperative visual analogue scale scores but a trend to higher fusion rate in group 1 was seen (P = 0.07) at 6 months. There was a 40% incidence of early resorption with no significant differences in visual analogue scale scores or fusion rate between both groups. There is a 40% incidence of early resorption (≤4 mo) that had no significant effect on pain score or fusion rate. Resorption should be considered part of the fusion process and not necessarily a complication. 3.

Anterior lumbar interbody fusion for the treatment of postoperative spondylodiscitis.

ObjectiveTo analyze the clinical courses and outcomes after anterior lumbar interbody fusion (ALIF) for the treatment of postoperative spondylodiscitis.MethodsA total of 13 consecutive patients with postoperative spondylodiscitis treated with ALIF at our institute from January, 1994 to August, 2013 were included (92.3% male, mean age 54.5 years old). The outcome data including inflammatory markers (leukocyte count, C-reactive protein, erythrocyte sedimentation rate), the Oswestry Disability Index (ODI), the modified Visual Analogue Scale (VAS), and bony fusion rate using spine X-ray were obtained before and 6 months after ALIF.ResultsAll of the cases were effectively treated with combination of systemic antibiotics and ALIF with normalization of the inflammatory markers. The mean VAS for back and leg pain before ALIF was 6.8±1.1, which improved to 3.2±2.2 at 6 months after ALIF. The mean ODI score before ALIF was 70.0±14.8, which improved to 34.2±27.0 at 6 months after ALIF. Successful bony fusion rate was 84.6% (11/13) and the remaining two patients were also asymptomatic.ConclusionOur results suggest that ALIF is an effective treatment option for postoperative spondylodiscitis.

Injection of Bupivacaine into Disc Space to Detect Painful Nonunion after Anterior Lumbar Interbody Fusion (ALIF) Surgery in Patients with Discogenic Low Back Pain

PurposeBupivacaine is commonly used for the treatment of back pain and the diagnosis of its origin. Nonunion is sometimes observed after spinal fusion surgery; however, whether the nonunion causes pain is controversial. In the current study, we aimed to detect painful nonunion by injecting bupivacaine into the disc space of patients with nonunion after anterior lumbar interbody fusion (ALIF) surgery for discogenic low back pain.Materials and MethodsFrom 52 patients with low back pain, we selected 42 who showed disc degeneration at only one level (L4-L5 or L5-S1) on magnetic resonance imaging and were diagnosed by pain provocation on discography and pain relief by discoblock (the injection of bupivacaine). They underwent ALIF surgery. If the patients showed low back pain and nonunion 2 years after surgery, we injected bupivacaine into the nonunion disc space. Patients showing pain relief after injection of bupivacaine underwent additional posterior fixation using pedicle screws. These patients were followed up 2 years after the revision surgery.ResultsOf the 42 patient subjects, 7 showed nonunion. Four of them did not show low back pain; whereas 3 showed moderate or severe low back pain. These 3 patients showed pain reduction after injection of bupivacaine into their nonunion disc space and underwent additional posterior fixation. They showed bony union and pain relief 2 years after the revision surgery.ConclusionInjection of bupivacaine into the nonunion disc space after ALIF surgery for discogenic low back pain is useful for diagnosis of the origin of pain.

A Comparison of Radiostereometric Analysis and Computed Tomography for the Assessment of Lumbar Spinal Fusion in a Sheep Model

Study Design Prospective animal study. Objective The aim of this animal study is to evaluate the accuracy of radiostereometric analysis (RSA) compared with computed tomographic (CT) scan in the assessment of spinal fusion after anterior lumbar interbody fusion (ALIF) using histology as a gold standard. Methods Three non-adjacent ALIFs (L1–L2, L3–L4, and L5–L6) were performed in nine sheep. The sheep were divided into three groups of three sheep. All the animals were humanely killed immediately after having the last scheduled RSA. The lumbar spine was removed and in vitro fine cut CT and histopathology were performed. Results Using histological assessment as the gold standard for assessing fusion, RSA demonstrated better results (100% sensitivity and 66.7% specificity; positive predictive value [PPV] = 27.3%, negative predictive value [NPV] =100.0%) compared with CT (66.7% sensitivity and 60.0% specificity [PPV = 16.7%, NPV = 93.8%]). Conclusions RSA demonstrated higher sensitivity and specificity when compared with CT. Furthermore, RSA has the advantage of much lower radiation exposure compared with fine cut CT. Further studies are required to see if RSA remains superior to CT scan for the assessment spinal fusion in the clinical setting.Assessment of Class of Evidence (CoE) for individual studies of diagnostic test evaluationMethodological principleStudy design Prospective cohort designX Retrospective cohort design Case–control designBroad spectrum of patients with expected condition a Appropriate reference standard usedXAdequate description of test and reference for replicationXBlinded comparison with appropriate referenceXReference standard performed independently of testXEvidence levelII Note: Blank box indicates criterion not met, could not be determined, or information not reported by author or was not reported. aThis study contained nine animal subjects.

Quantitative Assessment of Retrograde Ejaculation Using Semen Analysis, Comparison With a Standardized Qualitative Questionnaire, and Investigating the Impact of rhBMP-2

This was a prospective study evaluating the incidence of retrograde ejaculation (RE) after anterior lumbar interbody fusion (ALIF) based on laboratory analysis of semen and urine. The purpose of this study was to investigate the incidence of RE based on quantitative semen analysis and to compare the rate with that identified using a standardized qualitative questionnaire administered by telephone. RE is a specific sexual dysfunction in which semen passes into the bladder during ejaculation. It has long been a known possible complication of ALIF associated with injury to the superior hypogastric plexus occurring during access to the anterior lumbar spine. Although reported in multiple studies, there is no standardized assessment for RE and many studies do not describe the methods by which it was assessed. Recently, there has been increased interest in ALIF-related RE with respect to the use of recombinant human bone morphogenetic protein (rhBMP-2). However, how RE was diagnosed remains loosely defined. One possible assessment of RE is to analyze semen and urine after ejaculation. Forty-one male patients undergoing ALIF with posterior pedicle screw instrumentation and fusion at L4-L5 and/or L5-L1 consented to participate in the study. The subjects went to a cryobank for preoperative semen and postejaculatory urine analysis. They returned to the cryobank 3 to 6 months after surgery for repeat testing. The semen analysis consisted of ejaculate volume, total sperm count, concentration, and motility, whereas the urine test reported postejaculatory voided urine for spermatozoa. Postoperatively, patients were called by the principle investigator who conducted an interview based on a standardized questionnaire (completed for 36 patients). Patients were considered to have RE based on the questionnaire if they reported less or no ejaculate fluid. These results were compared with those from the laboratory testing to evaluate the value of the questionnaire in assessing RE. rhBMP-2 was used in 21 of the cases. The incidence of RE was compared in these patients versus those in whom rhBMP-2 was not used. Four patients (9.8%) were diagnosed with RE based on the laboratory analysis, 2 of which resolved spontaneously. Based on the questionnaire, 15 (41.7%) patients reported having RE, including the 4 that were confirmed by laboratory testing. Of the 21 patients treated with rhBMP-2, 2 (9.5%) were diagnosed with RE, 1 of which resolved. Of the 20 patients treated without rhBMP-2, 2 (10.0%) had RE, 1 of which resolved. This study suggests that use of a questionnaire tends to overestimate the incidence of RE as compared with the quantitative semen and urine analysis. Contrary to recent studies using retrospective qualitative review, in this small group with quantitative analysis, use of rhBMP-2 was not related to an increased incidence of RE, with a rate of approximately 10% in both patients receiving, and those not receiving, rhBMP-2. Further study of a larger group using preoperative semen and urine analysis, postoperative standard questionnaire and postoperative semen analysis should be pursued to further investigate the occurrence of RE and to possibly assist in developing and validating a questionnaire for RE assessment.

Urological complications following use of recombinant human bone morphogenetic protein–2 in anterior lumbar interbody fusion

The goal of this study was to compare the urological complications in patients after anterior lumbar interbody fusion (ALIF) with and without the use of recombinant human bone morphogenetic protein-2 (rhBMP-2). The authors retrospectively reviewed the medical records of all patients who underwent ALIF with and without rhBMP-2 between January 2002 and August 2010. Patient demographic, operative, and complication information was analyzed. Male patients who underwent ALIF between L-4 and S-1 were contacted to assess postoperative urological complications. Of the 110 male patients who underwent ALIF and were included in this study, 59 were treated with rhBMP-2 and 51 did not receive rhBMP-2. The mean follow-up duration was 17.5 months for the rhBMP-2 group and 30.8 months for the control group. No difference was found regarding the total number of urological complications in the rhBMP-2 group versus the control group (22% vs 20%, respectively; p = 1.0) or for retrograde ejaculation specifically (8% vs 8%, respectively; p = 1.0). In this study, the use of rhBMP-2 with ALIF surgery was not associated with an increased incidence of urological complications and retrograde ejaculation when compared with control ALIF without rhBMP-2. Further prospective analyses that specifically look at these complications are warranted.

Recombinant human bone morphogenetic protein 2 labeled use in spinal surgery and sexual dysfunction.

Dear Sir, We have read with great interest the recent review article by Epstein, entitled “Pros, cons, and costs of INFUSE in spinal surgery”.[6] We would like to congratulate the author on the thorough review of the current findings on the controversial topic of the “off-label” use of bone morphogenetic protein INFUSE™ [recombinant human bone morphogenetic protein-2 (rhBMP-2); Medtronic, Memphis, TN, USA] in cervical, thoracic, and lumbar spine surgery.[6] We would also like to commend the author for listing sexual dysfunction among the complications reported in conjunction with the application of INFUSE™ and the LT Cage™,[6] as it is a complication that has not been mentioned in this context until recently.[17–22] Sexual dysfunction, particularly retrograde ejaculation (RE), was so far encountered only after anterior lumbar interbody fusion (ALIF), a procedure in which the application of INFUSE was approved by the US Food and Drug Administration (FDA).[14] It has been described in the articles by Burkus et al.[2] and Sasso et al.,[13] and clearly stated as “a potential adverse event which may occur with spinal fusion surgery with the INFUSE™ Bone Graft/LT-CAGE™ Lumbar Tapered Fusion Device” in the FDA Device Approval Summary of Safety and Effectiveness Data.[14] The underlying mechanism of the dysfunction is the inability of the internal vesical sphincter to contract during ejaculation, resulting in retrograde flow of semen to the urinary bladder.[13] As the muscle is innervated by the superior hypogastric plexus, i.e., a thin, retroperitoneal plexus of nerves overlying the lumbosacral junction, damage to the plexus during (or after) ALIF can denervate the bladder neck sphincter. To the best of our knowledge, we were the first to point out the connection between sexual dysfunction and rhBMP-2 use in spinal surgery.[17–22] The authors of the studies[19,20,22] have categorically denied this causal relationship, although they did not provide any explanation for the appearance of the dysfunction, months after the surgical procedures (according to the FDA's reporting),[14] which is in concordance with current findings on late inflammatory reactions and/or pressure exerted by the ectopic bone on the superior hypogastric plexus. Finally, by examining the articles cited by Epstein,[1,3–5,7–12,15,16,23–25] we did not find any mention of sexual dysfunction as a complication. Therefore, we would like to know what source the author referred to when stating sexual dysfunction as a complication of, if we understood correctly, “off-labeled” application of INFUSE™ in spinal surgery?

Clinical analysis of percutaneous facet screw fixation after anterior lumbar interbody fusion

The authors performed a retrospective study to evaluate the results of percutaneous facet screw fixation (PFSF) after anterior lumbar interbody fusion (ALIF) in comparison with the gold standard, post-ALIF pedicle screw fixation (PSF). Of 84 patients treated for degenerative spondylolisthesis or degenerative disc disease at the authors' institution, 44 underwent PFSF (Group 1) and 40 underwent PSF (Group 2 [control population]) after ALIF. Function was assessed using the Oswestry Disability Index (ODI) scoring system, and outcome was measured using the Macnab criteria. At 3, 6, 12, and 24 months after surgery, dynamic lateral (flexion-extension) radiography and computerized tomography scanning were conducted to evaluate the osseous union status. After a minimum follow-up period of 2 years, analysis showed no intergroup statistical difference in terms of ODI score and Macnab outcome criteria (p > 0.05). Excellent or good outcome was obtained in 40 (90.9%) of the 44 patients in Group 1 and 37 (92.5%) of the 40 patients in the control Group 2 (p > 0.05). No patient required a blood transfusion in either group. At 24 months after surgery fusion rates were 95.8% in Group 1 and 97.5% in Group 2. The results of PFSF following ALIF appear to be clinically equivalent to those achieved after PSF, and the procedure represents a safe and minimally invasive modality with which to achieve solid fusion in the lumbar spine.