Gurpreet S. Gandhoke

Radiographic and clinical outcomes following combined lateral lumbar interbody fusion and posterior segmental stabilization in patients with adult degenerative scoliosis

OBJECT A hybrid approach of minimally invasive lateral lumbar interbody fusion (LLIF) followed by supplementary open posterior segmental instrumented fusion (PSIF) has shown promising early results in the treatment of adult degenerative scoliosis. Studies assessing the impact of this combined approach on correction of segmental and regional coronal angulation, sagittal realignment, maximum Cobb angle, restoration of lumbar lordosis, and clinical outcomes are needed. The authors report their results of this approach for correction of adult degenerative scoliosis. METHODS Twenty-six patients underwent combined LLIF and PSIF in a staged fashion. The patient population consisted of 21 women and 5 men. Ages ranged from 40 to 77 years old. Radiographic measurements including coronal angulation, pelvic incidence, lumbar lordosis, and sagittal vertical axis were taken preoperatively and 1 year postoperatively in all patients. Concurrently, the visual analog score (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Short Form-36 (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores were used to assess clinical outcomes in 19 patients. RESULTS At 1-year follow-up, all patients who underwent combined LLIF and PSIF achieved statistically significant mean improvement in regional coronal angles (from 14.9° to 5.8°, p < 0.01) and segmental coronal angulation at all operative levels (p < 0.01). The maximum Cobb angle was significantly reduced postoperatively (from 41.1° to 15.1°, p < 0.05) and was maintained at follow-up (12.0°, p < 0.05). The mean lumbar lordosis-pelvic incidence mismatch was significantly improved postoperatively (from 15.0° to 6.92°, p < 0.05). Although regional lumbar lordosis improved (from 43.0° to 48.8°), it failed to reach statistical significance (p = 0.06). The mean sagittal vertical axis was significantly improved postoperatively (from 59.5 mm to 34.2 mm, p < 0.01). The following scores improved significantly after surgery: VAS for back pain (from 7.5 to 4.3, p < 0.01) and leg pain (from 5.8 to 3.1, p < 0.01), ODI (from 48 to 38, p < 0.01), and PCS (from 27.5 to 35.0, p = 0.01); the MCS score did not improve significantly (from 43.2 to 45.5, p = 0.37). There were 3 major and 10 minor complications. CONCLUSIONS A hybrid approach of minimally invasive LLIF and open PSIF is an effective means of achieving correction of both coronal and sagittal deformity, resulting in improvement of quality of life in patients with adult degenerative scoliosis.

Preoperative prealbumin level as a risk factor for surgical site infection following elective spine surgery

Background: Nutritional status is a critical factor in patient outcomes in a variety of medical contexts. In the surgical fields, there is substantial evidence suggesting that clinical outcomes including infection risk and surgical efficacy may be affected by preoperative nutritional status. The purpose of this study is to evaluate preoperative serum prealbumin levels, the currently preferred serum biomarker of nutritional deficiency, in relation to the risk of developing a surgical site infection. Methods: A retrospective case–control series was conducted comparing prospectively collected preadmission serum prealbumin levels to the risk for surgical site infection following elective spine surgery. The analysis was conducted under an approved institutional quality assurance protocol. Patients were identified by querying the department billing codes for deep wound washouts over a 3-year period. A cohort of 32 patients with preoperative prealbumin levels who underwent spine surgery complicated by postoperative deep tissue infection was identified. This was compared against a case–control cohort of 74 patients who underwent spine surgery and did not experience postoperative infection. Clinical variables included demographic information, body mass index, smoking, diabetes, steroid use, length of the procedure, and length of hospital stay. The data were analyzed using multivariate Cox regression. Results: Two variables: Preoperative prealbumin < 20 and diabetes were both statistically significant predictors for the risk of developing a postoperative infection with hazard ratios of 2.12 (95% confidence interval [CI]: 1.03–4.37) and 2.22 (95% CI: 1.04–4.75), respectively. Conclusions: Our results reinforce the relationship between preoperative nutritional status and outcomes in elective spine surgery. The data indicate that preoperative prealbumin levels may be useful in risk stratification. Further study is needed to determine whether nutritional supplementation may reduce the risk of infection.

The effect of vancomycin powder on human dural fibroblast culture and its implications for dural repair during spine surgery

OBJECTIVE Surgical site infections (SSIs) are a major source of morbidity after spinal surgery. Several recent studies have described the finding that applying vancomycin powder to the surgical bed may reduce the incidence of SSI. However, applying vancomycin in high concentrations has been shown in vitro to inhibit osteoblast proliferation and to induce cell death. Vancomycin may have a deleterious effect on dural healing after repair of an intentional or unintentional durotomy. This study was therefore undertaken to assess the effect of different concentrations of vancomycin on a human dura mater cell culture. METHODS Human dura intended for disposal after decompressive craniectomy was harvested. Explant primary cultures and subcultures were subsequently performed. Cells were characterized through common staining and immunohistochemistry. A growth curve was performed to assess the effect of different concentrations of vancomycin (40, 400, and 4000 μg/ml) on cell count. The effect of vancomycin on cellular shape, intercellular arrangement, and viability was also evaluated. RESULTS All dural tissue samples successfully developed into fusiform cells, demonstrating pseudopod projections and spindle formation. The cells demonstrated vimentin positivity and also had typical features of fibroblasts. When applied to the cultures, the highest dose of vancomycin induced generalized cell death within 24 hours. The mean (± SD) cell counts for control, 40, 400, and 4000 μg/ml were 38.72 ± 15.93, 36.28 ± 22.87, 19.48 ± 6.53, and 4.07 ± 9.66, respectively (p < 0.0001, ANOVA). Compared with controls, vancomycin-exposed cells histologically demonstrated a smaller cytoplasm and decreased pseudopodia formation resulting in the inhibition of normal spindle intercellular arrangement. CONCLUSIONS When vancomycin powder is applied locally, dural cells are exposed to a concentration several times greater than when delivered systemically. In this in vitro model, vancomycin induced dural cell death, inhibited growth, and altered cellular morphology in a concentration-dependent fashion. Defining a safe vancomycin concentration that is both bactericidal and also does not inhibit normal dural healing is necessary.

A Cost-Effectiveness Comparison Between Open Transforaminal and Minimally Invasive Lateral Lumbar Interbody Fusions Using the Incremental Cost-Effectiveness Ratio at 2-Year Follow-up.

BACKGROUND Direct cost comparisons between minimally invasive spine surgeries and the open options are rare. OBJECTIVE To compare healthcare costs associated with open transforaminal lumbar interbody fusion (TLIF) and minimally invasive lateral lumbar interbody fusion (LLIF) by calculating the incremental cost-effectiveness ratio (ICER) and to calculate the thresholds for minimum clinically important difference and minimum cost-effective difference for patient-reported outcome measures at the 2-year follow-up. METHODS Forty-five patients who underwent single-level TLIF and 29 patients who underwent single-level stand-alone LLIF were included in the comparison. All costs from diagnosis through the 2-year follow-up were available from a comprehensive single-center data bank within a unified hospital system. Payment provided for all spine-related medical resource use from the time of diagnosis through 2 years was recorded. A 0% discount rate was applied. Quality-adjusted life-years (QALYs) were calculated from the EuroQol-5D collected in an unbiased manner. Difference in total cost per QALY gained for LLIF minus that for TLIF was assessed as the estimate of the ICER from a US perspective. RESULTS Significant improvements were observed at the 2-year follow-up for both TLIF and LLIF with the Short Form-36 physical component summary, Oswestry Disability Index, visual analog scale back pain and leg pain scores, and EuroQol-5D. ICER calculations revealed similar mean cumulative QALYs gained at the 2-year interval (0.67 for TLIF and 0.60 for LLIF; P = .33). Median total costs of care after TLIF and LLIF were

The Influence of Pelvic Incidence and Lumbar Lordosis Mismatch on Development of Symptomatic Adjacent Level Disease Following Single-Level Transforaminal Lumbar Interbody Fusion

44 068 and

319 Predictive Value of Intraoperative Neurophysiological Monitoring During Spine Surgery: A Prospective Analysis of 4489 Consecutive Patients.

45 574, respectively (P = .96). Minimum cost-effective difference thresholds with an anchor of <

A prospective, multi-center clinical and radiographic outcomes evaluation of ChronOS strip for lumbar spine fusion.

50 000 per QALY were higher than minimum clinically important difference thresholds for all patient-reported outcome measures. Total mean cost and EuroQol-5D were statistically equivalent between the 2 treatment groups. CONCLUSION TLIF and LLIF produced equivalent 2-year patient outcomes at an equivalent cost-effectiveness profile.

A Multi-Center Evaluation of Clinical and Radiographic Outcomes Following High-Grade Spondylolisthesis Reduction and Fusion.

BACKGROUND Annual incidence of symptomatic adjacent level disease (ALD) following lumbar fusion surgery ranges from 0.6% to 3.9% per year. Sagittal malalignment may contribute to the development of ALD. OBJECTIVE To describe the relationship between pelvic incidence-lumbar lordosis (PI-LL) mismatch and the development of symptomatic ALD requiring revision surgery following single-level transforaminal lumbar interbody fusion for degenerative lumbar spondylosis and/or low-grade spondylolisthesis. METHODS All patients who underwent a single-level transforaminal lumbar interbody fusion at either L4/5 or L5/S1 between July 2006 and December 2012 were analyzed for pre- and postoperative spinopelvic parameters. Using univariate and logistic regression analysis, we compared the spinopelvic parameters of those patients who required revision surgery against those patients who did not develop symptomatic ALD. We calculated the predictive value of PI-LL mismatch. RESULTS One hundred fifty-nine patients met the inclusion criteria. The results noted that, for a 1° increase in PI-LL mismatch (preop and postop), the odds of developing ALD requiring surgery increased by 1.3 and 1.4 fold, respectively, which were statistically significant increases. Based on our analysis, a PI-LL mismatch of >11° had a positive predictive value of 75% for the development of symptomatic ALD requiring revision surgery. CONCLUSIONS A high PI-LL mismatch is strongly associated with the development of symptomatic ALD requiring revision lumbar spine surgery. The development of ALD may represent a global disease process as opposed to a focal condition. Spine surgeons may wish to consider assessment of spinopelvic parameters in the evaluation of degenerative lumbar spine pathology.

Lateral lumbar interbody fusion

INTRODUCTION A single-center study to define the sensitivity and specificity of intraoperative neurophysiological monitoring in detecting new neurological deficits. METHODS A cohort of 4989 consecutive (2962 male and 2027 female) patients operated on over 3 years was evaluated. Subgroup analysis was performed for patients undergoing posterior cervical intervention (n = 1373) and posterior lumbar fusion surgery (n = 2420). Sensitivity and specificity were determined using Bayesian techniques. Impact of length of surgery and of variables, including age, sex, body mass index, diabetes mellitus, hypertension, coronary artery disease, cerebrovascular disease, and history of smoking, on the development of a new neurodeficit was defined. RESULTS Of 4489 patients, 426 patients (9.4%) had significant intraoperative somatosensory evoked potential (SSEP) changes. New postoperative neurological deficits occurred in 121 (2.7%) patients. Twenty-five of 426 patients (5.8%) with neuromonitoring changes developed a new neurodeficit. Ninety-six of 4063 patients (2.3%) with no changes developed a new neurodeficit. In posterior cervical interventions, 98 of 1373 (7.1%) developed SSEP changes and 13 of 98 (13.2%) patients developed a new neurodeficit, whereas 49 (3.8%) developed a new neurodeficit without any changes in intraoperative monitoring (IOM). In posterior lumbar fusion SSEPs, electromyographs (EMGs), and pedicle screw stimulation was utilized. Two hundred forty-nine of 2420 (10.2%) patients developed IOM changes and 8 of 249 (3.2%) patients developed a new neurodeficit, while 37 (1.7%) developed a new neurodeficit without changes in IOM. In the entire cohort SSEPs had sensitivity 20.7% and specificity of 90.8%. In the posterior cervical cohort, SSEPs had s sensitivity of 20.9% and a specificity of 93.7%. In the lumbar fusion cohort, multimodality monitoring including SSEPs, EMGs, and pedicle screw stimulation had a sensitivity of 17.8% and a specificity of 88.6%. Neither the length of surgery nor did any analyzed patient-related variable have a statistically significant impact on the development of a new neurodeficit. CONCLUSION The strength of SSEPs is their negative predictive value. A cost-utility analysis for IOM in spine surgery should be undertaken.

Graft subsidence as a predictor of revision surgery following stand-alone lateral lumbar interbody fusion

This prospective clinical study evaluated the use of a composite bone void filler (ChronOS Strip, DePuy Synthes, West Chester, PA, USA), combined with bone marrow aspirate plus local autologous bone, in a series of patients undergoing instrumented posterolateral spinal fusion with interbody support. Seventy-six patients were enrolled and treated per protocol at 13 clinical sites. At 24 months, 55/76 patients (72%) were evaluated, with 49/76 (65%) having sufficient data to determine the primary endpoint. The primary endpoint, posterolateral fusion success, was achieved in 48/54 (88.9%) patients at 12 months and in 45/49 (91.8%) patients at 24 months. At all follow-up time points, statistically significant improvements were observed when compared to baseline in back and leg pain and functional status as measured by visual analog scale, Oswestry Disability Index and 12-Item Short Form health surveys. This prospective multi-center series provides evidence that the composite bone void filler, when applied posterolaterally with instrumentation, bone marrow aspirate and/or local autologous bone and concomitant interbody support, can be used to achieve a successful posterolateral fusion, resulting in improvements in clinical outcomes in patients with degenerative disc disease.