Transforaminal Lumbar Interbody Fusion Procedure Research Articles

Intraoperative Decrease in Amplitude of Somatosensory-Evoked Potentials of the Lower Extremities with Interbody Fusion Cage Placement During Lumbar Fusion Surgery

STUDY DESIGN A retrospective analysis was performed. OBJECTIVE To characterize neurophysiological data of patients who had a decrease in amplitude of somatosensory-evoked potentials (SSEP) of the lower extremities secondary to interbody fusion cage placement during lumbar fusion surgery with no alert of the electromyography (EMG). SUMMARY OF BACKGROUND DATA The most consistently used and studied modalities of neurophysiological monitoring during spine surgery are SSEPs, motor-evoked potentials (MEPs), and EMG. In general, it is accepted that MEPs along with SSEPs are used to detect spinal cord injury and EMGs are used to detect nerve root injury. METHODS The medical records of a consecutive series of 115 patients who had undergone a transforaminal lumbar interbody fusion (TLIF) procedure in which SSEPs, MEPs, and EMGs were utilized for neurophysiological monitoring were retrospectively reviewed. RESULTS One hundred fifteen cases of TLIF procedures were reviewed. The follow-up was 2 years after the last procedure. A total of 5 cases that demonstrated intraoperative SSEP changes were found. The age range for these cases was from 39 to 81 years (mean age, 61 yr). All 5 patients developed SSEP changes that were secondary to interbody fusion cage placement. All 5 cases demonstrated reversal of the SSEP changes to baseline after removal of the interbody cage. Three of these cases had no new postoperative neurological findings. However, given that these 3 cases of SSEP change were associated with a surgical event that improved secondary to an intervention (in this case removal of the interbody cage), those cases were classified as presumed positive. Two of the 5 cases were in fact associated with a new postoperative neurological deficit. CONCLUSION To our knowledge this study demonstrates the first reported SSEP alerts that were associated with a posterior lumbar interbody cage placement without a corresponding EMG alert.

Biomechanical comparison of unilateral and bilateral pedicle screws fixation for transforaminal lumbar interbody fusion after decompressive surgery -- a finite element analysis

BackgroundLittle is known about the biomechanical effectiveness of transforaminal lumbar interbody fusion (TLIF) cages in different positioning and various posterior implants used after decompressive surgery. The use of the various implants will induce the kinematic and mechanical changes in range of motion (ROM) and stresses at the surgical and adjacent segments. Unilateral pedicle screw with or without supplementary facet screw fixation in the minimally invasive TLIF procedure has not been ascertained to provide adequate stability without the need to expose on the contralateral side. This study used finite element (FE) models to investigate biomechanical differences in ROM and stress on the neighboring structures after TLIF cages insertion in conjunction with posterior fixation.MethodsA validated finite-element (FE) model of L1-S1 was established to implant three types of cages (TLIF with a single moon-shaped cage in the anterior or middle portion of vertebral bodies, and TLIF with a left diagonally placed ogival-shaped cage) from the left L4-5 level after unilateral decompressive surgery. Further, the effects of unilateral versus bilateral pedicle screw fixation (UPSF vs. BPSF) in each TLIF cage model was compared to analyze parameters, including stresses and ROM on the neighboring annulus, cage-vertebral interface and pedicle screws.ResultsAll the TLIF cages positioned with BPSF showed similar ROM (<5%) at surgical and adjacent levels, except TLIF with an anterior cage in flexion (61% lower) and TLIF with a left diagonal cage in left lateral bending (33% lower) at surgical level. On the other hand, the TLIF cage models with left UPSF showed varying changes of ROM and annulus stress in extension, right lateral bending and right axial rotation at surgical level. In particular, the TLIF model with a diagonal cage, UPSF, and contralateral facet screw fixation stabilize segmental motion of the surgical level mostly in extension and contralaterally axial rotation. Prominent stress shielded to the contralateral annulus, cage-vertebral interface, and pedicle screw at surgical level. A supplementary facet screw fixation shared stresses around the neighboring tissues and revealed similar ROM and stress patterns to those models with BPSF.ConclusionsTLIF surgery is not favored for asymmetrical positioning of a diagonal cage and UPSF used in contralateral axial rotation or lateral bending. Supplementation of a contralateral facet screw is recommended for the TLIF construct.

Restoration of lordosis and disk height after single‐level transforaminal lumbar interbody fusion

To study radiographic and clinical outcomes after transforaminal lumbar interbody fusion (TLIF) in order to determine the impact of TLIF on lumbar lordosis, intervertebral height and improvement in clinical outcome measures. Forty-five patients who had undergone a single-level TLIF procedure for a single-level degenerative condition were retrospectively reviewed and their clinical histories, degree of pre- and post-operative lumbar lordosis, intervertebral height, and cage position recorded. Clinical assessment included use of modified Odom's criteria and a visual analog scale (VAS) for back and leg pain. At 21 months, the patients had gained an average of 3.6° of lumbar lordosis and 4.5 mm disc height. Change in disc height was significantly associated with an anterior cage position while lumbar lordosis was unaffected by cage position. A spondylolisthesis subgroup demonstrated 31% reduction in the magnitude of anterior slip. Less lordosis was associated with worse back and leg pain as assessed by VAS and greater disk heights were associated with higher Odom's criteria scores. Patients with persistent leg pain at final follow-up had less lumbar lordosis and intervertebral height than patients without leg pain. Intervertebral height and lumbar lordosis reconstruction are important for achieving good surgical results; guidance regarding the likely changes in lumbar lordosis and disk height after TLIF is provided by our findings.

Comparative Effectiveness of Minimally Invasive Versus Open Transforaminal Lumbar Interbody Fusion

Retrospective cohort comparison between minimally invasive (MIS) and open transforaminal lumbar interbody fusion (TLIF). To assess 2 earlier unstudied endpoints (duration of narcotic use and return to work) and long-term pain, disability, and quality of life (QOL) for MIS-TLIF versus open-TLIF. MIS-TLIF for lumbar spondylolithesis theoretically allows for surgical treatment of back and leg pain while minimizing blood loss and tissue injury. Although earlier studies have shown shorter hospital stay and equivocal 6 and 24 month outcomes with MIS-TLIF versus open-TLIF, the effect of MIS techniques on postoperative narcotic use and return to work are poorly understood. Thirty patients undergoing MIS-TLIF (n = 15) or open-TLIF (n = 15) for grade I degenerative spondylolithesis-associated back and leg pain were enrolled. Two-year outcomes were assessed through phone interview and it included pain [visual analog scale (VAS)], low-back disability (Oswestry disability index), EuroQol-5D, occupational disability, and narcotic use. MIS-TLIF versus open-TLIF cohorts were similar at baseline. Median [interquartile range (IQR)] length of hospitalization after surgery was significantly less for MIS-TLIF versus open-TLIF [3 (3 to 3) vs 5.5 (4 to 6) d], P = 0.001. MIS-TLIF versus open-TLIF patients showed similar 2-year improvement in VAS for back pain, VAS for leg pain, Oswestry disability index, and EuroQol-5D scores. Overall, median (IQR) length of postoperative narcotic use was 3.0 (1.4 to 4.6) weeks and significantly shorter for MIS-TLIF versus open-TLIF patients [2.0 (1.0 to 3.0) vs 4.0 (1.4 to 4.6) wk, P = 0.008]. Overall, median (IQR) time to return to work was 13.9 (2.2 to 25.5) weeks and significantly shorter for MIS-TLIF versus open-TLIF patients [8.5 (4.4 to 21.4) vs 17.1 (1.8 to 35.9) wk, P = 0.02]. Both MIS-TLIF and open-TLIF provide long-term improvement in pain, disability, and EuroQol-5D in patients with back and leg pain from grade I degenerative spondylolithesis. However, MIS-TLIF may allow for shortened hospital stays, reduced postoperative narcotic use, and accelerated return to work, reducing both direct medical costs and indirect costs of lost work productivity associated with TLIF procedures.

Transforaminal lumbar interbody fusion for the treatment of degenerative spondylolisthesis

Degenerative spondylolisthesis (DS) is a common cause of lumbal and lumbosacral pain as well as radicular pain. Retention and fusion is a good treatment option. Some patients have a symptomatic adjacent degenerative disc disease (DDD) in addition to DS. In these cases the adjacent segments should be fused as well. There are different techniques of fusion available, such as posterior with instrumentation or additional anterior support. This study evaluated results of transforaminal lumbar interbody fusion (TLIF) in patients with monosegmental DS and adjacent DDD. A total of 28patients with monosegmental DS and adjacent DDD were included into the study (all patients with bisegmental posterior instrumentation and fusion, 14patients 1 level TLIF, 14patients 2 level TLIF). Before surgery and 12months after surgery the following measurements were made: pain (visual analog scale VAS), Oswestry disability index (ODI) and plain radiographs with radiometric analysis. In a sub-analysis patients with 1 and 2 level TLIF were compared. Pain reduction (average VAS from 8.7-3.1) and ODI (63% to 28%) showed significant improvements. Radiometric analysis showed a significant disc height reconstruction and a significant reduction of spondylolisthesis (TLIF level with spondylolisthesis). Bisegmental anterior support showed a significantly better relordosation compared to monosegmental anterior support. The complication rate was 21.4% including hemorrhages, dura leakage, wound infection and adjacent segment degeneration. There were no fatal complications. The TLIF procedure is a safe and effective treatment for monosegmental DS with adjacent symptomatic DDD. Clinical results (pain, function) show no difference between both kinds of fusion (dorsal fusion and instrumentation versus dorsal fusion with instrumentation and TLIF) for the adjacent DDD. However, additional anterior support is more effective for relordosation of the segment. This could have impact on the mid-term and long-term outcome or in cases of adjacent segment fusion.

Perioperative surgical complications of transforaminal lumbar interbody fusion: a single-center experience

Since its original description in 1982, transforaminal lumbar interbody fusion (TLIF) has grown in popularity as a means for achieving circumferential fusion. The authors sought to define the perioperative complication rates of the TLIF procedure at a large academic medical center. For all eligible patients from a consecutive series of 531 TLIF procedures, the institution's complication database and the medical record were reviewed to identify complications. Medical, nonprocedure-related complications such as myocardial infarction and pulmonary embolism were excluded due to inconsistency in the recording of these complications in the database. Rates were calculated for each type of complication, and subgroup analysis was performed to investigate the effect of previous lumbar surgery, and of multilevel versus single-level interbody fusion on complication rates. Odds ratios were calculated and evaluated using chi-square analysis. Five hundred thirty-one patients underwent a TLIF procedure during the study period. Two hundred forty-four patients (46%) had undergone a previous lumbar operation. Interbody fusion was performed at 1 level in 317 patients, at 2 levels in 188 patients, at 3 levels in 24 patients, and at 4 levels in 2 patients. One hundred thirty-five patients (25.4%) had at least one procedure-related complication. The most common complications were durotomy (14.3% of patients) and infection (3.8% of patients). Symptomatic screw misplacement (2.1% of patients) and interbody cage migration (1.8% of patients) were less common complications. The overall complication rate was greater in those patients who had undergone a previous operation (OR 1.75, 95% CI 1.18-2.59; p < 0.01) and in those who had multilevel surgery (OR 1.54, 95 % CI 1.04-2.28; p = 0.03), and the incidence of durotomy was higher in patients who had a previous operation (OR 1.75, 95% CI 1.07-2.87; p = 0.03). These differences were statistically significant. Durotomy also occurred more frequently in patients who had multilevel interbody fusion (OR 1.49, 95% CI 0.92-2.43; p = 0.13). A trend toward higher infection rates in those patients who underwent multilevel interbody fusion was observed (OR 1.5, 95% CI 0.62-3.68; p = 0.49), but this was not statistically significant. Infection rates did not differ between revision and first-time surgeries. Transforaminal lumbar interbody fusion has gained widespread popularity as a procedure for achieving arthrodesis in the lumbar spine. Complications occurred more often in patients undergoing revision surgery or multilevel interbody fusion. Durotomy and infection were the most common complications in this series.

TLIF for symptomatic disc degeneration: a retrospective study of 100 patients

The goal of a fusion of the lumbar spine is to obtain a primary solid arthrodesis thus to alleviate pain. Different circumferential fusion techniques have been described such as combined anterior-posterior fusion (APF), instrumented posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF). The TLIF procedure has rapidly gained popularity; because of its posterolateral extracanalar discectomy and fusion, it has been reported as a safe technique, without the potential complications described when using combined APF and PLIF techniques. A retrospective clinical and radiographic study was performed. The database of our Center was interrogated in a retrospective way to extract data from patients that underwent a one or two level lumbar fusion with TLIF approach. All patients had symptomatic disc degeneration of the lumbar spine. One hundred and fourteen levels fused from 2003 to 2008. All patients were operated in the same center. All the patients were operated by the same surgical team. Patients were evaluated preoperatively and postoperatively at 1 and 3 months and 1 and 2 years follow-up. The spine was approached through a classic posterior midline incision and subperiosteal muscular detachment. The side of facetectomy was chosen according to the subject's symptoms of leg pain if present. A posterolateral annulotomy was made and subtotal discectomy was performed and the hyaline cartilage of endplates was removed. Once the surgeon was satisfied with endplate preparation, a banana shaped allograft spacer was inserted through the annulotomy and placed anteriorly. Additional autograft locally harvested from decompression was packed behind the allograft spacer in all cases. Laminae and the remaining contralateral facet joint were decorticated, and packed with bone graft (local autologous and allograft chips in some cases). The posterior fusion was instrumented with pedicle screws and titanium rods. The TLIF procedure had led to shortened surgical times, less neurologic injury, and improved overall outcomes. The introduction of the TLIF procedure has allowed surgeons to achieve successful fusion without the risk of nerve root tethering that is seen so frequently with standard PLIF techniques.

Complications and perioperative factors associated with learning the technique of minimally invasive transforaminal lumbar interbody fusion (TLIF)

Before the advent of minimally invasive spine surgery (MIS), open transforaminal lumbar interbody fusion (TLIF) was performed to treat spondylosis, spondylolisthesis, and spondylolysis. Minimally invasive TLIF has recently become more popular based upon the premise that a smaller, less traumatic incision should afford better recovery and outcomes. However, the learning curve associated with this technique must be considered. To analyze the perioperative factors associated with the learning curve in patients who underwent MIS TLIF versus open TLIF, we identified 22 patients who underwent TLIF from 2005 to 2008 within levels L4–S1 by the senior author (D.C.). Patients were subdivided into two groups according to whether they underwent: (i) MIS TLIF (10 patients, the first MIS TLIF procedures performed by D.C.); or (ii) open TLIF (12 patients). Preoperative, perioperative and postoperative factors were evaluated. Patients who underwent MIS TLIF had a statistically significant lower intraoperative transfusion rate, and rate of required postoperative surgical drains; and shorter periods of required drainage, and time to ambulation. However, the MIS TLIF group tended to have a higher rate of complications, which might have been associated with the learning curve. Both groups had a minimum of 1-year follow-up.

Biomechanical evaluation of an expandable meshed bag augmented with pedicle or facet screws for percutaneous lumbar interbody fusion

Objective To evaluate the biomechanics of lumbar motion segments instrumented with stand-alone OptiMesh system augmented with posterior fixation using facet or pedicle screws and the efficacy of discectomy and disc distraction. Background context OptiMesh bone graft containment system has been used for vertebral compression fractures and percutaneous lumbar interbody fusion. The filled mesh bag serves as the interbody device providing structural support to the motion segment being fused. No biomechanical data of this new device are available in the literature. Methods Twenty-four fresh human cadaveric lumbar motion segments were divided into two groups. In the control group, multidirectional flexibility testing was conducted after an intact condition and standard transforaminal lumbar interbody fusion (TLIF) procedure. In the OptiMesh group, testing was performed following intact, stand-alone OptiMesh procedure, OptiMesh with facet screws (placed using the transfacet approach), and OptiMesh with pedicle screws and rods. Range of motion (ROM) was calculated for each surgical treatment. The lordosis and disc height change of intact and instrumented specimens were measured in the lateral radiographs to evaluate the disc space distraction. In the OptiMesh group, cyclic loading in flexion extension (FE) was applied to measure cage subsidence or collapse (10,000 cycles at 6 Nm). After biomechanical testing, all the specimens were dissected to inspect the discectomy and end plate preparation. The area of discectomy was measured. Results The mean ROM of the intact specimens was 2.7°, 7.4°, and 7.2° in axial torsion (AT), lateral bending (LB), and FE, respectively. There was no difference between the control group and OptiMesh group. The mean ROM of the stand-alone OptiMesh system decreased to 2.4°, 5.1°, and 4.3° in AT, LB, and FE. The ROM decreased to 0.9° in AT, 2.2° in LB, and 0.9° in FE with OptiMesh system and facet screws. On average, OptiMesh system with pedicle screws and rods reduced the ROM to 1.3° in AT, 1.6° in LB, and 1.1° in FE. Compared with the intact condition and stand-alone OptiMesh system, both posterior fixation options had significant statistical difference (p<.001). In AT, ROM of facet screws was lower than that of pedicle screws (p<.05). There was no statistical difference between the facet and pedicle screws in LB and FE (p>.05). The mean volume of bone graft packed into each bag was 8.3±1.5 cc. The average increase of lordosis was 0.6°±1.0° after meshed bag was deployed. The average distraction achieved by the OptiMesh system was 1.0±0.6 mm. The average prepared area of discectomy was 42% of the total disc. The disc height change after cyclic loading was 0.2 mm. No subsidence or collapse was noticed. Conclusions The OptiMesh system offers large volume of bone graft in the disc space with small access portals. The OptiMesh system had similar construct stability to that of standard TLIF procedure when posterior fixation was applied. However, the amount of distraction was limited without additional distraction tools. With the anterior support provided by the expandable meshed bag, facet screws had comparable construct stability to that of pedicle screws. Slightly higher stability was observed in facet screws in AT.

Transforaminal lumbar interbody fusion for traumatic lumbar spondylolisthesis

To evaluate the clinical outcome, effectiveness and safety of the surgical management of traumatic lumbar spondylolisthesis with transforaminal lumbar interbody fusion (TLIF) with short segmental instrumentation fixation. A retrospective review of a consecutive series of 24 patients with traumatic lumbar spondylolisthesis treated with TLIF procedure was carried out. Intraoperative spinal cord monitoring was used to confirm the peripheral neural function intact during the reduction of the spondylolisthesis. Preoperative clinical and radiographic evaluation of all cases were originally collected prospectively. Data regarding blood loss, operative time, duration of hospital stay, radiographic fusion, instrumentation failure and clinical result were collected and observed at regular follow-up periods. All patients were engaged in high-energy accidents in the lower back and 16 patients had concomitant injuries. The mean operative time was 124 min, mean blood loss was 350 mL, and mean hospital stay was 6.5 days. There were no complications such as incision infection, cerebrospinal fluide (CSF) leakage and nerve root injury and so on. All patients demonstrated a solid lumbar interbody fusion within 4 months, and no evidence of spondylolisthesis correction loss, instrumentation failure and loosing. They all were completely asymptomatic, with normal neurologic findings, and had resumed their previous level of physical activities on the final follow-up. Meticulous clinical examination and careful imaging assessment could assist an early diagonosis in cases of traumatic lumbar spondylolisthesis. Performing open reduction and the TLIF procedure as soon as possible could restore segmental stability and painless function. The TLIF procedure was a safe, effective technique to treat traumatic lumbar spondylolisthesis.

Reduction and transforaminal lumbar interbody fusion with posterior fixation versus transsacral cage fusion in situ with posterior fixation in the treatment of Grade 2 adult isthmic spondylolisthesis in the lumbosacral spine

In situ transsacral fusion in the treatment of low-grade isthmic spondylolisthesis has rarely been reported. The authors treated 13 cases of L-5 Grade 2 isthmic spondylolisthesis associated with collapsed disc space and osteoporosis by using transsacral fusion and fixation, and compared its clinical and radiological outcomes with the results of transforaminal lumbar interbody fusion (TLIF) and instrumental reduction in 21 patients. The authors retrospectively analyzed 21 patients in Group A who were treated with reduction and TLIF, and 13 patients in Group B who were treated with transsacral cage fusion. Oswestry Disability Index and visual analog scale scores of back and leg pain were used to evaluate clinical outcomes. Radiological parameters for assessment included the percentage of slippage, whole lumbar lordosis, and lumbosacral angle. Operative data, fusion rate, and perioperative complications were recorded as well. The mean operation time and blood loss in Group B was less than that in Group A. Both groups realized good recovery from previous symptoms. The decrease in back and leg pain after surgery was significant within each group, without much difference between the 2 groups. No significant differences were found in lumbosacral angle, whole lumbar lordosis, visual analog scale score, and Oswestry Disability Index score between the 2 groups after surgery. The solid fusion rate was 95.2% in Group A and 92.3% in Group B. In Group A, 2 patients suffered from graft site pain, 1 had a superficial infection, and 1 had screw loosening; in Group B, dural tears were found in 2 patients, transient S-1 paresthesia in 2, and extensor hallucis longus muscle weakness in 1. For patients with a collapsed disc space and poor bone quality, posterior in situ transsacral cage fusion may be used as an alternative to the TLIF procedure. The short-term clinical and radiological outcomes in the transsacral cage group were comparable with those in the TLIF group, although with a relatively higher neurological complication rate.

Vertebral osteolysis originating from subchondral cyst end plate defects in transforaminal lumbar interbody fusion using rhBMP-2. Report of two cases

Background Context Vertebral osteolysis has been reported as a complication of off-label recombinant human bone morphogenetic protein-2 (rhBMP-2) use in transforaminal lumbar interbody fusion (TLIF). It has been postulated that end plate violation during disc space preparation, rhBMP-2 overdosing, or a combination thereof can contribute to the development of vertebral osteolysis when rhBMP-2 is used in the lumbar interspace. Purpose To present two cases of vertebral osteolysis that occurred after TLIF in which rhBMP-2 was used. In each case, the osteolysis originated from subchondral cysts that were present on preoperative computed tomographic (CT) scans. Study Design Case report. Methods Two patients underwent instrumented TLIF using INFUSE (Medtronic, Inc., Littleton, MA, USA) on an absorbable collagen sponge carrier. In each patient, approximately 4 mg of rhBMP-2 was placed anteriorly in the disc space with 0.1 mg of rhBMP-2 being placed inside a polyetheretherketone interbody cage. Morcellized allograft bone mixed with demineralized bone matrix was also placed in the disc space and cage. The remaining rhBMP-2 was placed posterolaterally on the contralateral side. Each patient presented with worsening back pain approximately 3 to 4 months postoperatively and CT scans revealed osteolysis affecting the L4 and L5 vertebral bodies. The osteolysis appeared to originate from preoperative vertebral defects caused by subchondral cysts. Results One patient underwent removal of the interbody cage at the L4–L5 level and revision of the fusion with iliac crest autograft. At 15-month follow-up, he had no complaints of back pain, and CT scanning revealed solid fusion across the L4–L5 disc space. The other patient was offered revision of his fusion but declined any further surgery. At 2-year follow-up, that patient had persistent back pain but still declined any further surgery. A CT scan revealed unchanged osteolysis at the L4 and L5 levels. Conclusions It has been proposed that rhBMP-2-induced vertebral osteolysis occurring in TLIF procedures may be secondary to end plate violation during disc preparation or overdosing of rhBMP-2. Although overdosing may have also contributed to vertebral osteolysis in our two cases, the end plate violation from subchondral cyst formation that was present on preoperative CT scans seemed to be the origin of the osteolysis suggesting that the presence of preoperative subchondral cysts may be an additional risk factor for development of osteolysis in these patients.

Resident learning curve for minimal-access transforaminal lumbar interbody fusion in a military training program

Minimal-access transforaminal lumbar interbody fusion (TLIF) has gained popularity as a method of achieving interbody fusion via a posterior-only approach with the aim of minimizing injury to adjacent tissue. While many studies have reported successful outcomes, questions remain regarding the potential learning curve for successfully completing this procedure. The goal of this study, based on a single resident's experience at the only Accreditation Council for Graduate Medical Education-approved neurosurgical training center in the US military, was to determine if there is in fact a significant learning curve in performing a minimal-access TLIF. The authors retrospectively reviewed all minimal-access TLIFs performed by a single neurosurgical resident between July 2006 and January 2008. Minimal-access TLIFs were performed using a tubular retractor inserted via a muscle-dilating exposure to limit approach-related morbidity. The accuracy of screw placement and operative times were assessed. A single resident/attending team performed 28 minimal-access TLIF procedures. In total, 65 screws were placed at L-2 (1 screw), L-3 (2 screws), L-4 (18 screws), L-5 (27 screws), and S-1 (17 screws) from the resident's perspective. Postoperative CTs were reviewed to determine the accuracy of screw placement. An accuracy of 95.4% (62 of 65) properly placed screws was noted on postoperative imaging. Two screws (at L-5 in the patient in Case 17 and at S-1 in the patient in Case 9) were lateral, and no revision was needed. One screw (at L-4 in Case 24) was 1 mm medial without symptoms or the need for revision. In evaluating the operative times, 2 deformity cases (Grade III spondylolisthesis) were excluded. The average operating time per level in the remaining 26 cases was 113.25 minutes. The average time per level for the first 13 cases was 121.2 minutes; the amount of time decreased to 105.3 minutes for the second group of 13 cases (p = 0.25). In summary, minimal-access TLIF can be safely performed in a training environment without a significant complication rate due to the expected learning curve.

Minimally invasive versus open transforaminal lumbar interbody fusion

BackgroundAvailable clinical data are insufficient for comparing minimally invasive (MI) and open approaches for transforaminal lumbar interbody fusion (TLIF). To date, a paucity of literature exists directly comparing minimally invasive (MI) and open approaches for transforaminal lumbar interbody fusion (TLIF). The purpose of this study was to directly compare safety and effectiveness for these two surgical approaches. Materials and MethodsOpen or minimally invasive TLIF was performed in 63 and 76 patients, respectively. All consecutive minimally invasive TLIF cases were matched with a comparable cohort of open TLIF cases using three variables: diagnosis, number of spinal levels, and history of previous lumbar surgery. Patients were treated for painful degenerative disc disease with or without disc herniation, spondylolisthesis, and/or stenosis at one or two spinal levels. Clinical outcome (self-report measures, e.g., visual analog scale (VAS), patient satisfaction, and MacNab's criteria), operative data (operative time, estimated blood loss), length of hospitalization, and complications were assessed. Average follow-up for patients was 37.5 months. Results:The mean change in VAS scores postoperatively was greater (5.2 vs. 4.1) in theopen TLIF patient group (P = 0.3). MacNab's criteria score was excellent/good in 67% and 70% (P = 0.8) of patients in open and minimally invasive TLIF groups, respectively. The overall patient satisfaction was 72.1% and 64.5% (P = 0.4) in open and minimally invasive TLIF groups, respectively. The total mean operative time was 214.9 min for open and 222.5 min for minimally invasive TLIF procedures (P = 0.5). The mean estimated blood loss for minimally invasive TLIF (163.0 ml) was significantly lower (P < 0.0001) than the open approach (366.8 ml). The mean duration of hospitalization in the minimally invasive TLIF (3 days) was significantly shorter (P = 0.02) than the open group (4.2 days). The total rate of neurological deficit was 10.5% in the minimally invasive TLIF group compared to 1.6% in the open group (P = 0.02). Conclusions: Minimally invasive TLIF technique may provide equivalent long-term clinical outcomes compared to open TLIF approach in select population of patients. The potential benefit of minimized tissue disruption, reduced blood loss, and length of hospitalization must be weighted against the increased rate of neural injury-related complications associated with a learning curve.

Complications associated with single-level transforaminal lumbar interbody fusion

Background context The transforaminal lumbar interbody fusion (TLIF) procedure has become an increasingly popular means of obtaining a circumferential fusion while avoiding the morbidity of the anterior approach. Concerns remain, however, regarding the clinical efficacy and safety of its use. Purpose The purpose of this study was to evaluate the complications of the single-level TLIF procedure. The difference in complications observed with the use of iliac crest autograft compared with rhBMP-2 will be assessed. Study design Retrospective cohort study; a review of complications. Methods Patients who underwent a single-level TLIF between January 2004 to May 2007 with either autograft iliac crest or rhBMP-2 were identified. A retrospective review of these patients included operative reports, pre- and postoperative medical records, most recent postoperative dynamic and static lumbar radiographs, and computed tomography scans (when available). Results A total of 130 patients met the study criteria; 119 patients were available for follow-up, with an average radiographic follow-up of 19.1 months and an average clinical follow-up of 27.6 months. Thirty-three patients received iliac crest autograft and 86 patients received rhBMP-2. Complications occurred in 40 of the 119 study patients (33.6%). The autograft group had a higher complication rate (45.5% vs. 29.1%), but the difference was not statistically significant (p=.09). Complications in the autograft group included persistent donor-site pain (30.3%), donor-site infection (3.1%), lumbar wound infection (6.1%), and postoperative radiculitis (3.0%). Complications in the rhBMP-2 group included postoperative radiculitis (14.0%), vertebral osteolysis (5.8%), ectopic bone formation (2.3%), and lumbar wound infection (3.5%). A hydrogel sealant (Duraseal; Confluent Surgical Inc., Waltham, MA, USA) was used in 37 out of 86 patients in the rhBMP-2 group. The use of this sealant decreased the rate of postoperative radiculitis in the rhBMP-2 group from 20.4% to 5.4% (p=.047). The radiographic nonunion rate at most recent follow-up was 3.0% in the autograft group and 3.5% (p=.90) in the rhBMP-2 group. Conclusions The most common complications in the autograft group were related to the donor site. The most common complication in the rhBMP-2 group was postoperative radiculitis, the incidence of which is reduced by the use of a hydrogel sealant.

The use of RhBMP-2 in single-level transforaminal lumbar interbody fusion: a clinical and radiographic analysis

The "off label" use of rhBMP-2 in the transforaminal lumbar interbody fusion (TLIF) procedure has become increasingly popular. Although several studies have demonstrated the successful use of rhBMP-2 for this indication, uncertainties remain regarding its safety and efficacy. The purpose of this study is to evaluate the clinical and radiographic outcomes of the single-level TLIF procedure using rhBMP-2. Patients who underwent a single-level TLIF between January 2004 and May 2006 with rhBMP-2 were identified. A retrospective evaluation of these patients included operative report(s), pre- and postoperative medical records, and dynamic and static lumbar radiographs. Patient-reported clinical outcome measures were obtained from a telephone questionnaire and included a modification of the Odom's criteria, a patient satisfaction score, and back and leg pain numeric rating scale scores. Forty-eight patients met the study criteria and were available for follow-up (avg. radiographic and clinical follow-up of 19.4 and 27.4 months, respectively). Radiographic fusion was achieved in 95.8% of patients. Good to excellent results were achieved in 71% of patients. On most recent clinical follow-up, 83% of patients reported improvement in their symptoms and 84% reported satisfaction with their surgery. Twenty-nine patients (60.4%) reported that they still had some back pain, with an average back pain numeric rating score of 2.8. Twenty patients (41.7%) reported that they still had some leg pain, with an average leg pain numeric rating score was 2.4. Thirteen patients (27.1%) had one or more complications, including transient postoperative radiculitis (8/48), vertebral osteolysis (3/48), nonunion (2/48), and symptomatic ectopic bone formation (1/48). The use of rhBMP-2 in the TLIF procedure produces a high rate of fusion, symptomatic improvement and patient satisfaction. Although its use eliminates the risk of harvesting autograft, rhBMP-2 is associated with other complications that raise concern, including a high rate of postoperative radiculitis.

Surgical treatment of adult degenerative spondylolisthesis by instrumented transforaminal lumbar interbody fusion in the Han nationality

The transforaminal lumbar interbody fusion (TLIF) procedure was developed to provide the surgeon with a fusion procedure that may reduce many of the risks and limitations associated with posterior lumbar interbody fusion, yet produce similar stability in the spine. There are few large series with long-term follow-up data regarding instrumented TLIF and placement of 1 diagonal polyetheretherketone (PEEK) cage. The authors performed a prospective study to evaluate the outcome and safety of instrumented TLIF with 1 diagonal PEEK cage for degenerative spondylolisthesis in the Han nationality in China. Between May 2001 and April 2006, 60 patients (35 men and 25 women; mean age 55.5 years, range 45-70 years) with symptomatic degenerative spondylolisthesis underwent the TLIF procedure with 1 diagonal PEEK cage and additional pedicle screw internal fixation at the authors' institution. The inclusion criteria involved degenerative spondylolisthesis (Grades I and II) in patients with chronic low-back pain with or without leg pain. One patient had a postoperative temporary motor and sensory deficit of the adjacent nerve root. Reoperation was required in 1 patient because of pedicle screw migration. One patient developed a pseudarthrosis and had increasing complaints of low-back pain 1 year postoperatively and underwent a subsequent revision surgery. Two patients had nerve root symptomatic compression resulting from cage migration and insufficient decompression after surgery, and they underwent revision. Two patients had a dural tear that required fibrin glue application during surgery. No implant fracture or subsidence occurred in any patient. Clinically, the pain index and Oswestry Disability Index (ODI) score improved significantly from before surgery to the 2-year follow-up. In the TLIF group, the pain index improved from 69 to 25 (p < 0.001). The postoperative ODI showed a significant postoperative reduction of disability during the whole period of follow-up (p < 0.001). The preoperative mean ODI score was 32.3 (16-80), and postoperative 13.1 (0-28). Disc space height and foraminal height were restored by the surgery and maintained at the latest follow-up time. In the authors' experience, instrumented TLIF with 1 diagonal PEEK cage can be a surgical option for treatment of degenerative spondylolisthesis in the Han nationality in China.

Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches

The authors review and compare posterior lumbar interbody fusion (PLIF) with transforaminal lumbar interbody fusion (TLIF). A review of the literature is performed wherein the history, indications for surgery, surgical procedures with their respective biomechanical advantages, potential complications, and grafting substances are presented. Along with the technical advancements and improvements in grafting substances, the indications and use of PLIF and TLIF have increased. The rate of arthrodesis has been shown to increase given placement of bone graft along the weight-bearing axis. The fusion rate across the disc space is further enhanced with the placement of posterior pedicle screw–rod constructs and the application of an osteoinductive material. The chief advantages of the TLIF procedure compared with the PLIF procedure included a decrease in potential neurological injury, improvement in lordotic alignment given graft placement within the anterior column, and preservation of posterior column integrity through minimizing lamina, facet, and pars dissection.

Comparative study of PILF and TLIF treatment in adult degenerative spondylolisthesis

This study is to compare the therapeutic effect of posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) with pedicle screw fixation on treatment in adult degenerative spondylolisthesis. A retrospective analysis of 187 patients to compare the complications and associated predictive factors of the two techniques of one level lumbar fusion. Ninety-one had PLIF with two cages and pedicle fixation (group 1), and ninety-six had TLIF with one cage and pedicle fixation (group 2). The two groups had similar age and sex distribution, and level of pain. Inclusion criteria and outcome measurements were identical in both groups. The two groups were operated on with autograft and cage with pedicle fixation. Before surgery and at the 2-year follow-up, pain (VAS) and functional disability (JOA) were quantified. The results showed there were no intraoperative deaths in our study. In the end 176 cases had 2-year follow-up while 11 cases were lost to follow-up. The follow-up rate was 93.4% (85/91) in the PLIF group and 94.8% (91/96) in the TLIF group. All patients had bone fusion, and there were no cases of cage extrusion. The pain index improved from 7.08 +/- 1.13 to 2.84 +/- 0.89 in PLIF patients and improved from 7.18 +/- 1.09 to 2.84 +/- 0.91 in TLIF patients (P < 0.001). There were 42 cases of excellent, 29 cases of good, 11 cases of general, and 3 cases of poor results in PLIF group. There were 46 cases of excellent, 31 case of good, 12 case of general, and 2 cases of poor results in TLIF group. The JOA score in all patients was 84.1% of good or excellent (83.5% in PLIF and 84.6% in TLIF, P > 0.05). The average preoperative slip was 30.1 +/- 7.2% in PLIF group while in the TLIF it was 31.4 +/- 8.3%. Immediately post operatively it was reduced to 7.3 +/- 2.1% and 7.4 +/- 2.7% and at last F/U it was 8.1 +/- 2.8% and 8.2 +/- 2.6%, respectively. The average of reduction rate was 75.2 +/- 6.4% in PLIF and 75.4 +/- 6.2 in TLIF on the initial post operatively X-ray, and 72.6 +/- 5.2% and 72.4 +/- 5.4% on the follow-up. The percentage rate, reduction rate and lost of reduction rate between the two groups was similar (P > 0.05). The average pre operative disk and foramen height in the PLIF group improved from 6.8 +/- 2.3 and 14.2 +/- 1.7 preoperatively to 11.6 +/- 1.5 and 18.7 +/- 1.8 post operatively, respectively. At last follow up there was minimal lost of correction down to 11.24 +/- 1.2 and 18.1 +/- 1.8, respectively. Similarly in the TLIF group, pre operative disk and foramen height were improved from 6.7 +/- 1.7 and 14.1 +/- 1.8 to 11.4 +/- 1.6 and 18.5 +/- 1.6 immediately post operative. At last follow up minimal lost of correction was noted with average disc height of 11.3 +/- 1.4 and 18.2 +/- 1.7. Both techniques achieve statistical significance in restoration of disc and foraminal (P < 0.01); however, there was no statistical difference between the two techniques. In conclusion, interbody fusion with either a PLIF technique or a TLIF technique provides good outcomes in the treatment of adult degenerative spondylolisthesis. The TLIF procedure is simpler and is as safe and effective as the PLIF technique.

DORSAL LUMBAR INTERBODY FUSION FOR CHRONIC AXIAL, MECHANICAL LOW BACK PAIN

AbstractLUMBAR SPINAL FUSION is a popular method for treating degenerative disc disease leading to chronic low back pain. Some of the techniques most commonly undertaken are posterior lumbar interbody fusion and transforaminal lumbar interbody fusion. These techniques have their own advantages and disadvantages. In this article, we briefly describe a modified technique, dorsal lumbar interbody fusion, which retains the advantages and avoids the disadvantages of the others. The goal of this procedure is to combine the aggressive decompression of both the thecal sac and bilateral nerve roots and symmetrical bilateral graft placement obtained via the posterior lumbar interbody fusion with the transforaminal placement of interbody grafts obtained via the transforaminal lumbar interbody fusion procedure. This modification has several advantages: it permits more aggressive removal of the disc bilaterally, larger and more symmetrical lordotic-shaped carbon fiber cages and structural allograft can be placed bilaterally, and the nerve roots can be aggressively decompressed bilaterally.