Introduction:. Circumferential arthrodesis of the spine may be achieved by posterior-only or anterior and posterior surgery. Posterior-based interbody fusions have significant limitations including unreliable improvement of segmental lordosis and variable rates of post-operative radiculopathy. Combined anterior and posterior surgery introduces significant cost and peri-operative morbidity. The purpose of this paper is to report the radiographic and clinical outcomes of posterior-based circumferential arthrodesis using a novel expandable interbody cage. Methods:. A prospective pilot clinical trial with one year follow-up of the only expandable cage approved by the FDA for interbody application. Clinical outcomes measured include ODI and VAS for back and leg. Radiographic outcomes include arthrodesis rates based upon CT scan. Statistical significance for change in health status was calculated using Student's t-test. Results:. 10 consecutive patients (11 levels) with lumbar degenerative pathology underwent circumferential arthrodesis with a transforaminal interbody approach. 10 of 11 levels were fused based upon CT scan. ODI scores improved a median of 37 to 20 at 6 months and 17 at one year (p = 0.0003). The VAS for back and leg pain likewise from 6 to 2 at 12 months (p = −.003). No patient reported an increase in leg pain from pre-op to post-op. One patient with a 2-level fusion had a non-union at 1 level requiring revision surgery. Conclusion:. Circumferential arthrodesis with a TLIF approach is an important technique for the management of lumbar degenerative pathology. The experience with a novel expandable TLIF cage demonstrates excellent results based upon clinical outcome and fusion rates. The expandable interbody cage allows in-situ height increase which is useful for optimizing clinical and radiographic outcomes in TLIF surgery

Obesity is an increasing public health concern associated with increased perioperative complications and expense in lumbar spine fusions. While open and mini-open fusions such as transforaminal lumbar interbody fusion (TLIF) and minimally invasive TLIF (MIS-TLIF) are more challenging in obese patients, new MIS procedures like oblique lateral lumbar interbody fusion (OLLIF) may improve perioperative outcomes in obese patients relative to TLIF and MIS-TLIF. The purpose of this study is to determine the effects of obesity on perioperative outcomes in OLLIF, MIS-TLIF, and TLIF. This is a retrospective cohort study. We included patients who underwent OLLIF, MIS-TLIF, or TLIF on three or fewer spinal levels at a single Minnesota hospital after conservative therapy had failed. Indications included in this study were degenerative disc disease, spondylolisthesis, spondylosis, herniation, stenosis, and scoliosis. We measured demographic information, body mass index (BMI), surgery time, blood loss, and hospital stay. We performed summary statistics to compare perioperative outcomes in MIS-TLIF, OLLIF, and TLIF. We performed multivariate regression to determine the effects of BMI on perioperative outcomes controlling for demographics and number of levels on which surgeries were operated. OLLIF significantly reduces surgery time, blood loss, and hospital stay compared to MIS-TLIF, and TLIF for all levels. MIS-TLIF and TLIF do not differ significantly except for a slight reduction in hospital stay for two-level procedures. On multivariate analysis, a one-point increase in BMI increased surgery time by 0.56 ± 0.47 minutes (p = 0.24) in the OLLIF group, by 2.8 ± 1.43 minutes (p = 0.06) in the MIS-TLIF group, and by 1.7 ± 0.43 minutes (p < 0.001) in the TLIF group. BMI has positive effects on blood loss for TLIF (p < 0.001) but not for OLLIF (p = 0.68) or MIS-TLIF (p = 0.67). BMI does not have significant effects on length of hospital stay for any procedure. Obesity is associated with increased surgery time and blood loss in TLIF and with increased surgery time in MIS-TLIF. Increased surgery time may be associated with increased perioperative complications and cost. In OLLIF, BMI does not affect perioperative outcomes. Therefore, OLLIF may reduce the disparity in outcomes and cost between obese and non-obese patients

Transforaminal lumbar interbody fusion (TLIF) using an implanted cage is the gold standard surgical treatment for disc diseases such as disc collapse and spinal cord compression, when more conservative medical therapy fails. Titanium (Ti) alloys are widely used implant materials due to their superior biocompatibility and corrosion resistance. A new Ti-6Al-4V TLIF cage concept featuring an I-beam cross-section was recently proposed, with the intent to allow bone graft to be introduced secondary to cage implantation. In designing this cage, we desire a clear pathway for bone graft to be injected into the implant, and perfused into the surrounding intervertebral space as much as possible. Therefore, we have employed shape optimization to maximize this pathway, subject to maintaining stresses below the thresholds for fatigue or yielding. The TLIF I-beam cage (Fig. 1(a)) with an irregular shape was parametrically designed considering a lumbar lordotic angle of 10°, and an insertion angle of 45° through the left or right Kambin's triangles with respect to the sagittal plane. The overall cage dimensions of 30 mm in length, 11 mm in width and 13 mm in height were chosen based on the dimensions of other commercially available cages. The lengths (la, lp) and widths (wa, wp) of the anterior and posterior beams determine the sizes of the cage's middle and posterior windows for bone graft injection and perfusion, so they were considered as the design variables for shape optimization. Five dynamic tests (extension/flexion bending, lateral bending, torsion, compression and shear compression, as shown in Fig. 2(b)) for assessing long term cage durability (10. 7. cycles), as described in ASTM F2077, were simulated in ANSYS 15.0. The multiaxial stress state in the cage was converted to an equivalent uniaxial stress state using the Manson-Mcknight approach, in order to test the cage based on uniaxial fatigue testing data of Ti-6Al-4V. A fatigue factor (K) and a critical stress (σcr) was introduced by slightly modifying Goodman's equation and von Mises yield criterion, such that a cage design within the safety design region on a Haigh diagram (Fig. 2) must satisfy K ≤ 1 and σcr ≤ SY = 875 MPa (Ti-6Al-4V yield strength) simultaneously. After shape optimization, a final design with la = 2.30 mm, lp = 4.33 mm, wa = 1.20 mm, wp = 2.50 mm, was converged upon, which maximized the sizes of the cage's windows, as well as satisfying the fatigue and yield strength requirements. In terms of the strength of the optimal cage design, the fatigue factor (K) under dynamic torsion approaches 1 and the critical stress (σcr) under dynamic lateral bending approaches the yield strength (SY = 875 MPa), indicating that these two loading scenarios are the most dangerous (Table 1). Future work should further validate whether or not the resulting cage design has reached the true global optimum in the feasible design space. Experimental validation of the candidate TLIF I-beam cage design will be a future focus. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Study design. Prospective randomized study. Objective. Primary aim of this study was to compare clinical and radiological results of transforaminal lumbar interbody fusion (TLIF) with posterolateral (interlaminar) instrumented lumbar fusion (PLF) in adult low grade (Meyerding 1 & 2) spondylolisthesis patients. Background data. Theoretically, TLIF has better radiological result than PLF in spondylolisthesis in most of the studies. Method. 24 patients of low grade adult spondylolisthesis were randomly allocated to one of the two groups: group 1- PLF and group 2-TLIF. Study period was between August 2010 to March 2013. All patients were operated by a single surgeon (CN). Posterior decompression was performed in all patients. Average follow up period was 18.4 months. Quality of life was accessed with Visual analogue scale and Oswestry Low Back Pain Disability Index. Fusion was assessed radiologically by CT scan and X-ray. Result. Though fusion was significantly better in TLIF group, clinical outcome including relief of back pain and neurogenic claudication were better in PLF group. Rate of complication was also lower in PLF group. Conclusion. Considering the low complication rate and similar or better clinical results, posterolateral instrumented lumbar fusion is the better option in low grade adult spondylolisthesis

Objective. To compare between the CAMISS-TLIF group and the OP-TLIF group in the clinical efficacy and radiographic manifest. Methods. This study was a registration study, selected 27 patients with lumbar spondylolisthesis from May 2011 to March 2014 in our hospital. Patients in one group are treated with computer assisted navigation minimally invasive TLIF (CAMISS -TLIF) while the others are treated with the OP-TLIF (OPEN-TLIF). The former group has 13 cases while the latter group has 14 cases. We collected information and present statistical analysis on the following aspects in order to compare the two different surgical methods of treatment. They are the operation duration, blood loss, days of hospitalisation, the preoperative and follow-up JOA and JOA improvement rate, the preoperative and follow-up ODI scores, the preoperative and follow-up VAS and Odom's criteria. By analysing the follow-up CT results, we compare the pedicle screw accuracy rate between the two groups in order to make a comprehensive assessment of these two surgical methods. Results. There is a significant difference in blood loss, follow-up JOA improvement rate and follow-up ODI scores between the CAMISS-TLIF group and OP-TLIF group (P <0.05), while in other fields there is no statistically significant differences. Conclusion. CAMISS-TLIF surgical approach has an advantage of less blood loss, less muscle stripping, smaller surgical trauma and more quickly recovery after surgery

Purpose. To review the outcome of multilevel (≥4) instrumented lumbar fusion to sacrum / pelvis performed for degenerative conditions. Methods. Clinical data of 47 consecutive patients from 2002 to 2012 were reviewed retrospectively. Inclusion criteria included fusion from at least L2 to S1 / pelvis, i.e. minimum of 4 levels. Imaging was assessed for restoration of normal sagittal profile as well as subsequent fusion. EQ5D, OSD and VAS scores pre-op and at 6 months post op were analysed. Average age at surgery was 64 years (50–78). Thirteen cases were primary and 34 revisions. Indications were axial back pain either associated with sagittal imbalance (40%) or leg pain (36%) and leg pain alone in 10%. Results. The intra-operative blood loss averaged 2222 (250–7000) ml with 40% re-infusion from cell-saver. The average surgical duration was 268 minutes. Proximal extent of instrumentation was T2 (1), T3 (1), T4 (2), T8 (1), T9 (1), T10 (17), T11 (2), T12 (5), L1 (4) and L2 (13). TLIF's were done in 20 cases mostly at the base of the construct. Pedicle subtraction osteotomies were performed in 14 revision cases. Dural tears occurred in 14 cases, all revision cases except one. Wound infection occurred in 3 cases. Except for transient quadriceps weakness related to osteotomy, no neurological complications occurred. One patient deceased peri-operatively. Subsequent revision was required in 13 cases for instrumentation failure. OSD score improved by 15.3 points on average, which is clinically and statistically significant. Conclusion. Long lumbar fusions remain technically demanding with a high incidence of adverse events. This is due to the nature of revision surgery and high biomechanical demands on constructs. Surgical intervention can however be justified by the desperation of the cohort in terms of pain and poor function which can be modestly improved with this intervention. NO DISCLOSURES

Cahill et. al. published a large review of the use of BMP in spinal fusions. They reviewed the nationwide inpatient database, which represents approximately 25% of use U.S. Community Hospitals from the years 2002 to 2006. This included over 300,000 fusion type procedures. They noted increased complications with the use of anterior cervical procedures specifically increased complications with increased dysphasia and wound complications. Due to these concerns, the Food and Drug Administration released last year a public health notification about the potential life threatening complications related to the use of BMP in anterior cervical spine fusions. Joseph & Rampersaud noticed a 20% incidence of heterotopic ossification in patients undergoing this procedure versus only 8% for patients who had undergone fusions without BMP. Wong et. al. published a report on five cases of neurologic injury that relate to the use of BMP and the formation of heterotopic bone. Again, the suggestion of a barrier or closure defect was brought up and this may help minimise the risks; however, further work is noted. Multiple authors have noted a phenomenon of osteolysis occurring around graft fusion sites for the use of BMP. McCullen et. al. evaluated that 32 levels in 26 patients who had undergone a TLIF procedure. It is unclear the carcinogenic and tetraogenic effects of the use of BMP in the spine and also, the effects of repeat exposures on BMP has yet to be addressed. Finally, the long term cost and benefits of the use of BMP on the health care system has yet to be fully addressed. So in conclusion, BMP2 is effective in producing fusions especially in challenging environments, deformity, smoking and infection. However, the complications continue to be a concern especially with regards to interbody fusions as well as in the cervical spine