Surgical Interbody Research Group–radiographic assessment of interbody fusion devices: fusion criteria for anterior lumbar interbody surgery

Short-Term Comparison Between Unilateral Versus Bilateral Percutaneous Pedicle Screw Fixation in Short-Level Lateral Lumbar Interbody Fusion-A Prospective Randomized Study

STUDY DESIGN

Prospective randomized controlled trial.

OBJECTIVES

No prospective studies have directly compared clinical and radiographic outcomes of unilateral vs bilateral instrumented lateral lumbar interbody fusion (LLIF) for lumbar degenerative disease (LDD). We compared the short-term radiographic, clinical outcomes, and some complications of the unilateral percutaneous pedicle screw (PPS) (UPS) vs bilateral PPS (BPS) fixation in short-level spinal fusion with LLIF for LDD.

METHODS

This was a prospective randomized controlled study of 33 patients who underwent UPS or BPS fixation after LLIF for LDD; 18 patients were assigned to the UPS group and 15 patients to the BPS group. Clinical outcomes, complication rates, and fusion rates were assessed.

RESULTS

The two groups were similar in age, sex, preoperative diagnosis, and level of surgery. Blood loss, length of hospital stay, and numeric rating scale score one year after surgery did not differ between groups. The operative time was longer in the BPS than UPS group (120.2 vs 88.8 min, respectively; P = .029). Both groups showed improvement in disc height and dural sac in the immediate postoperative computed tomography and magnetic resonance imaging, which did not differ significantly between groups. The subsidence grade and fusion rate did not differ, but cage subsidence was more severe in the UPS than BPS group.

CONCLUSION

Unilateral and bilateral PPS fixation after LLIF yielded similar short-term clinical and radiological outcomes. However, severe cage subsidence was more common in the UPS group, which suggests that BPS fixation after LLIF may be a better choice over the long term.

Efficacy and Outcome Measurement of iFactor/ABM/P-15 in Lumbar Spine Surgery: A Systematic Review

STUDY DESIGN

Systematic Review.

OBJECTIVES

To determine the efficacy and overall outcomes of iFactor/ABM/P-15 following lumbar spine surgery.

METHODS

We performed a search of the Cochrane Library, Medline Ovid, PubMed, and SCOPUS databases from inception until August 2023. Eligible studies included outcomes of patients receiving iFactor following lumbar spine surgery. The primary outcomes of interest were fusion rates and iFactor efficacy after lumbar surgery in patients who received iFactor. Secondary outcomes included patient-reported outcomes and complication rates.

RESULTS

A total of 766 titles were initially screened. After inclusion criteria were applied, 5 studies (388 patients) were included, which measured overall outcomes of iFactor/ABM/P-15 following lumbar spine surgery. These studies showed acceptable reliability for inclusion based on the Methodical Index for Non-Randomized studies and Critical Appraisal Skills Programme assessment tools. iFactor/ABM/P-15 facilitated significantly faster bone development in various procedures while maintaining favorable clinical outcomes compared to traditional grafts.

CONCLUSIONS

This systematic review found that iFactor/ABM/P-15 use for lumbar spine surgery maintains similar managing patient-reported outcomes relative to other grafting methods. In regard to rates of fusion, iFactor/ABM/P-15 showed a significantly faster rate of fusion when compared to traditional grafts including allograft, autograft, demineralized bone matrix (DBM), and recombinant human bone morphogenetic protein-2 (rhBMP-2). Future multicenter randomized control trials with larger sample sizes are recommended to further assess iFactor/ABM/P-15 efficacy in lumbar spine surgery.

Lateral Lumbar Interbody Fusion With rhBMP-2 can Achieve High Fusion Rates in Adult Spine Deformity Surgeries

STUDY DESIGN

An ambispective, observational study of the prospective, institutional adult spine deformity (ASD) database.

OBJECTIVES

The study investigates the clinical and radiographic fusion rates with lateral interbody approach and rhBMP-2 in multiple-level lumbar fusion in the ASD population. Previous studies have reported over 10% pseudoarthrosis rate with multiple segment fusions. Lateral lumbar interbody fusion (LLIF) allows multiple-level, less-invasive access to the anterior lumbar spine. We hypothesized that fusion rates with lateral approach with rhBMP-2 use are superior to the published data on lumbar fusion in ASD patients.

METHODS

The institutional ASD database was searched to identify eligible patients with two or more levels of LLIF (T12-L5), >4 levels of posterior instrumentations and >2 years of follow-up between the years 2010 and 2018. Antero-posterior and lateral 36-inch standing radiographs for each patient and computed tomography scans in select patients were studied to ascertain fusion status and patients were divided into two groups based on fusion status.

RESULTS

The study included 179 patients with a mean age of 65.3 years and 74% female patients. The median number of interbody fusions was performed at 3 (IQR 3-4) levels. The mean follow-up duration was 4.4 years (SD = 1.9). 169 patients (94.5%) had successful arthrodesis, while 10 patients (5.5%) had radiological pseudoarthrosis at one level. Of the 10 patients, 8 (4.4%) were either clinically asymptomatic or had manageable back pain. Two patients (1.1%) required revision surgery for symptomatic pseudoarthrosis.

CONCLUSION

This is the largest known series of ASD patients investigating the fusion rates with multiple-level LLIFs. LLIF along with rhBMP-2 can achieve high fusion success across interbody fusion levels in multi-segmental ASD surgeries.

Fusion Assessment of Oblique Lumbar Interbody Fusion Using Demineralized Bone Matrix: A 2-Year Prospective Study

OBJECTIVE

Although several studies have reported successful fusion rates after oblique lumbar interbody fusion (OLIF) using allografts or dimerized bone matrix (DBM) instead of autografts, whether OLIF can achieve satisfactory solid fusion without the use of autografts remains unclear. This study investigated the real fusion rates after OLIF using allografts and DBM, which were evaluated using both dynamic radiographs and computed tomography scans.

METHODS

We enrolled 79 consecutive patients who underwent minimally invasive OLIF followed by percutaneous pedicle screw fixation. All patients were treated with OLIF between L2 and L5 and underwent radiographic and clinical follow-ups at 12, 18, and 24 months after surgery. Radiographic assessment of fusion was performed using the modified BrantigaSteffee-Fraser (mBSF) scale, which was categorized as follows: grades I (radiographic pseudoarthrosis), II (indeterminate fusion), and III (solid radiographic fusion). Other radiologic and clinical outcomes were evaluated using the following parameters: vertebral slippage distance, disc height, subsidence, Oswestry Disability Index (ODI), and visual analogue scale (VAS).

RESULTS

Clinical outcomes demonstrated significant improvements in the VAS scores for back pain, leg pain, and ODI after surgery. Subsidence was present in 34 cases (35.4%) at 12 months postoperatively, which increased to 47.9% and reached 50.0% at 1.5 years and 2 years after surgery, respectively. The solid fusion rate after OLIF was 32.3% at 1 year, increased to 58.3% at 1.5 years, and reached 72.9% at 2 years. Radiographic pseudoarthrosis was 24.0% at 1 year, which decreased to 6.3% at 1.5 years and 3.1% at 2 years.

CONCLUSION

OLIF is a safe and effective surgical procedure for the treatment of degenerative lumbar diseases. The mBSF scale, which simultaneously evaluates both dynamic angles and bone bridge formation, offers great reliability for the radiological assessment of fusion. Moreover, OLIF using allografts and DBM, which is performed on one or 2 levels at L2-5, can achieve satisfactory fusion rates within 2 years after surgery.

Anterior Lumbar Interbody Fusion in Elderly Patients: Peri- and Postoperative Complications and Clinical Outcome

BACKGROUND

 Anterior lumbar interbody fusion (ALIF) is an effective surgical technique for treating various lumbar pathologies, but its use in elderly patients is controversial. Data concerning complications and effectiveness are sparse. We investigated peri- and postoperative complications, radiographic parameters, and clinical outcome in elderly patients.

METHODS

 Patients ≥65 years who underwent ALIF between January 2008 and August 2020 were included in the study. All surgeries were performed through a retroperitoneal approach. Clinical and surgical data as well as radiologic parameters were collected prospectively and analyzed retrospectively.

RESULTS

 A total of 39 patients were included; the mean age was 72.6 (±6.3) years (range: 65-90 years); and the mean American Society of Anesthesiologists (ASA) risk classification was 2.3 (±0.6). A laceration of the left common iliac vein was the only major complication recorded (2.6%). Minor complications occurred in 20.5% of patients. Fusion rate was 90.9%. Reoperation rate at the index level was 12.8 and 7.7% in adjacent segments. The multidimensional Core Outcome Measures Index (COMI) improved from 7.4 (±1.4) to 3.9 (±2.7) after 1 year and to 3.3 (±2.6) after 2 years. Oswestry disability index (ODI) improved from 41.2 (±13.7) to 20.9 (±14.9) after 1 year and to 21.5 (±18.8) after 2 years. Improvements of at least the minimal clinically important change score of 2.2 and 12.9 points in the ODI and COMI after 2 years were noted in 75 and 56.3% of the patients, respectively.

CONCLUSION

 With careful patient selection, ALIF is safe and effective in elderly patients.

Postoperative cage migration and subsidence following TLIF surgery is not associated with bony fusion

Pseudarthrosis following transforaminal interbody fusion (TLIF) is not infrequent. Although cage migration and subsidence are commonly regarded as evidence of the absence of solid fusion, there is still no evidence of the influence of cage migration and subsidence on fusion. This study aimed to evaluate cage migration and subsidence using computed tomography (CT) DICOM data following lumbar interbody fusion. The effects of cage migration and subsidence on fusion and clinical outcomes were also assessed. A postoperative CT data set of 67 patients treated with monosegmental TLIF was analyzed in terms of cage position. To assess the effects of cage migration and subsidence on fusion, 12-month postoperative CT scans were used to assess fusion status. Clinical evaluation included the visual analog scale for pain and the Oswestry Disability Index. Postoperative cage migration occurred in 85.1% of all patients, and cage subsidence was observed in 58.2%. Radiological signs of pseudarthrosis was observed in 7.5% of the patients Neither cage migration nor subsidence affected the clinical or radiographic outcomes. No correlation was found between clinical and radiographic outcomes. The incidence of cage migration was considerable. However, as cage migration and subsidence were not associated with bony fusion, their clinical significance was considered limited.

The Significance of Extra-Cage Bridging Bone via Radiographic Lumbar Interbody Fusion Criterion

STUDY DESIGN

Prospective observational study.

OBJECTIVES

We aimed to analysis the distributional patterns of the intra- and extra-cage bridging bone (InCBB and ExCBB) and the significance of ExCBB using suggested lumbar interbody fusion criterion.

METHODS

This study included the patients with planned single-level transforaminal lumbar interbody fusion. We divided bridging bone into InCBB (in void of right or left cage) and ExCBB (outside of cages; anterior, posterior, intermediate, right, or left) and graded bridging scores from 0 to 2 on postoperative 1-year computed tomography. The fusion was defined as at least having one or more graded 2 and the evaluation were conducted twice by 2 raters.

RESULTS

Sixty-five patients were enrolled. All values of intra- and inter-rater reliability in left InCBB, anterior, and posterior ExCBB showed good agreements (≥0.75). Both InCBBs showed similar mean bridging scores (Rt:1.43 vs Lt:1.48), and in ExCBBs, the anterior was the highest (1.43), followed by the posterior (1.14); the right and left were the lowest (0.49 and 0.52 respectively). In subjects determined as fusion (85.4%), complete bridging was observed more in ExCBB (88.8%) than in InCBB (69.9%).

CONCLUSIONS

Given the higher bridging scores in both InCBBs and Ant. ExCBB, bone grafting is important promoting factor to increase the interbody bridging bone regardless of outside or in void of cages. Based on our suggested criterion, ExCBB has a greater proportion compared to InCBBs for determining the fusion and extra-cage bone grafting should be considered as important procedures for interbody fusion.

Characteristics of interbody bone graft fusion after transforaminal lumbar interbody fusion according to intervertebral space division

BACKGROUND

According to intervertebral space division, the characteristics of interbody bone graft fusion after transforaminal lumbar interbody fusion (TLIF) were assessed via computed tomography (CT) scan to provide a theoretical basis for selecting the bone grafting site of interbody fusion.

METHODS

The medical records of 57 patients with lumbar spinal stenosis and disc herniation treated with TLIF were analysed retrospectively. In total, 57 segments received lumbar interbody fusion. A thin-layer CT scan was performed to evaluate fusion in each zone of the fusion space.

RESULTS

The fusion rates were 57.89% (n = 33) in the anterior cage zone, 73.68% (n = 42) in the posterior cage zone, 66.67% (n = 38) in the decompression zone, 26.32% (n = 15) in the contralateral decompression zone and 94.74% (n = 54) in the inner cage zone. There were significant differences among the fusion rates of the five zones (P < 0.001). Further pairwise comparison revealed that the fusion rates in the inner cage significantly differed from the anterior and posterior cages and decompression and contralateral decompression zones (P = 0.001, 0.002, 0.001 and 0.001, respectively).

CONCLUSION

We think the central cage zone (i.e., inner cage) should be the focus of bone grafting. Although there is small volume of bone graft on the posterior cage zone, the fusion rate is relatively high, only secondary to the inner cage zone. The fusion rate is of the contralateral decompression zone is lower although there is a bone graft.

The SNAP Trial: 2-Year Results of a Double-Blind Multicenter Randomized Controlled Trial of a Silicon Nitride Versus a PEEK Cage in Patients After Lumbar Fusion Surgery

STUDY DESIGN

Randomized controlled trial.

OBJECTIVES

Lumbar interbody fusion with cages is performed to provide vertebral stability, restore alignment, and maintain disc and foraminal height. Polyetheretherketone (PEEK) is commonly used. Silicon nitride (Si₃N₄) is an alternative material with good osteointegrative properties. This study was designed to assess if Si₃N₄ cages perform similar to PEEK.

METHODS

A non-inferiority double-blind multicenter RCT was designed. Patients presenting with chronic low-back pain with or without leg pain were included. Single- or double-level instrumented transforaminal lumbar interbody fusion (TLIF) using an oblique PEEK or Si₃N₄ cage was performed. The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ). The non-inferiority margin for the RMDQ was 2.6 points on a scale of 24. Secondary outcomes included the Oswestry Disability Questionnaire (ODI), Visual Analogue Scales (VAS), SF-36 Physical Function, patient and surgeon Likert scores, radiographic evaluations for subsidence, segmental motion, and fusion. Follow-up was planned at 3, 6, 12, and 24-months.

RESULTS

Ninety-two patients were randomized (i.e. 48 to PEEK and 44 to Si₃N₄). Both groups showed good clinical improvements on the RMDQ scores of up to 5-8 points during follow-up. No statistically significant differences were observed in clinical and radiographic outcomes. Mean operative time and blood loss were statistically significantly higher for the Si₃N₄ cohort. Although not statistically significant, there was a higher incidence of complications and revisions associated with the Si₃N₄ cage.

CONCLUSIONS

There was insufficient evidence to conclude that Si₃N₄ was non-inferior to PEEK.

Evaluation of Spinal Fusion in Thoracic and Thoracolumbar Spine on Standard X-Rays: A New Grading System for Spinal Interbody Fusion

STUDY DESIGN

Retrospective evaluation of prospectively collected data.

OBJECTIVE

Analyzing time course and stages of interbody fusion of a uniformly operated cohort, defining a grading system and establishing diagnosis-dependent periods of bone healing.

METHODS

Sequential lateral radiographs of 238 patients (313 levels) with interbody fusion operated thoracoscopically were analyzed.

RESULTS

Evaluation of 1696 radiographs with a mean follow-up of 65.19 months and average numbers of 5.42 (2-18) images per level was performed. Diagnoses were Pyogenic Spondylitis (74), Fracture (96), Ankylosing Spondylitis (38) and Degenerative Disease (105). No case with Grade 2 deteriorated to Grade 5. On average, Grade 4 persisted for 113 days, Grade 3 for 197 days, Grade 2 for 286 days and Grade 1 for 316 days. The first 95% of levels ("Green Zone", ≤ Grade 2) fused at 1 year, the remaining 4% levels fused between 12 and 17 months ("Yellow Zone") and the last 1% ("Red Zone") fused after 510 days.

CONCLUSION

Sequential lateral radiographs permit evaluation of interbody fusion. Grade 2 is the threshold point for fusion; once accomplished, failure is unlikely. If fusion (Grade 2,1 or 0) is not reached within 510 days, it should be regarded as failed. The 510-day-threshold could reduce the necessity of CT scanning for assessing fusion.

Applications of the Crenel Lateral Interbody Fusion Procedure in Treatment for Adjacent Segments Degeneration of the Lumbar Spine

OBJECTIVE

To observe the clinical and radiological effect of crenel lateral interbody fusion (CLIF) procedure in the management of lumbar spine adjacent segment degenerative (ASD).

METHODS

Thirty-seven patients with lumbar spine ASD who underwent the CLIF procedure between June 2018 and December 2019 were included in the study. There were 13 males and 24 females, with a mean age of 64.30 ± 5.92 years. The VAS score of the back (VAS_Back) and legs (VAS_Leg), Oswestry Disability Index (ODI) score, the height of the intervertebral space (HIS), the height of the intervertebral foramen (HIF), the cross-sectional area (CSA) of the vertebral canal, segmental lordosis (SL), and lumbar lordosis (LL) were recorded before the operation, 2 weeks after the operation, 3 months after the operation, and at the last follow-up respectively. Clinical and radiological outcomes before and after the surgery were compared, and correlation and regression analyses were performed.

RESULTS

There were no vascular and nerve-related complications during the operation. The average follow-up time was 16.63 ± 4.24 months. The median of both VAS_Back and VAS_Leg was 7 before surgery and 1 at the last follow-up. Meanwhile, the average preoperative ODI score, HIS, HIF, CSA of the vertebral canal, LL, and SL was (67.48 ± 7.17) %, (4.80 ± 0.73) mm, (12.95 ± 2.07) mm, (59.52 ± 9.22) mm² , (37.22 ± 5.92)° and (4.78 ± 1.99)°, respectively. At the final follow-up, ODI score, HIS, HIF, CSA of the vertebral canal, LL, and SL was (7.07 ± 2.66) %, (9.44 ± 0.61) mm, (17.30 ± 1.90) mm, (70.49 ± 8.95) mm² , (44.67 ± 6.38)° and (13.44 ± 3.27)°, respectively. In the VAS_Back, VAS_Leg, ODI score, LL, SL, HIS, HIF, and CSA of the vertebral canal, the difference between preoperative and 2 weeks after the operation, 3 months after the operation, and the last follow-up were statistically significant (P < 0.05). However, the difference was not statistically significant between each time point after the operation in the CSA of the vertebral canal, LL, and SL (P > 0.05). Nonetheless, the difference was statistically significant in ODI between each time point after the operation (P < 0.05). VAS_Leg was associated with HIS, HIF, and CSA of the vertebral canal, while LL and SL were risk factors for low back pain.

CONCLUSION

Crenel lateral interbody fusion is an effective procedure in the management of lumbar ASD. Not only was the postoperative swift recovery due to minimal invasion, but also adequate LL and SL were achievable.

Successful fusion versus pseudarthrosis after spinal instrumentation: a comprehensive imaging review

PURPOSE

Following spinal instrumentation and fusion, differentiating between successful arthrodesis and pseudoarthrosis on imaging can be challenging. Interpretation of such examinations requires understanding both the expected evolution of postoperative findings and the subtle indicators of pseudoarthrosis across multiple imaging modalities. Due to this level of intricacy, many clinicians lack familiarity with the subject beyond the more rudimentary concepts.

METHODS

This review provides an in-depth overview of the imaging of the post-operative spine, with particular emphasis on differentiating between pseudoarthrosis and arthrodesis.

RESULTS

A comprehensive overview of imaging of the post-operative spine is given, including the most common imaging modalities utilized, the expected post-operative findings, imaging findings in pseudoarthrosis, and imaging definitions of fusion.

CONCLUSION

Differentiating between pseudoarthrosis and arthrodesis in the postoperative spine is complex, and requires a robust understanding of various findings across many different modalities.

Clinical and Cost-Effectiveness of Lumbar Interbody Fusion Using Tritanium Posterolateral Cage (vs. Propensity-Matched Cohort of PEEK Cage)

Introduction

Surgical management of degenerative lumbar spine disorders is effective at improving patient pain, disability, and quality of life; however, obtaining a durable posterolateral fusion after decompression remains a challenge. Interbody fusion technologies are viable means of improving fusion rates in the lumbar spine, specifically various graft materials including autograft, structural allograft, titanium, and polyether ether ketone. This study assesses the effectiveness of Tritanium posterolateral cage in the treatment of degenerative disk disease.

Methods

Nearest-neighbor 1:1 matched control transforaminal lumbar interbody fusion with PEEK vs. Tritanium posterior lumbar (PL) cage interbody fusion patients were identified using propensity scoring from patients that underwent elective surgery for degenerative disk diseases. Line graphs were generated to compare the trajectories of improvement in patient-reported outcomes (PROs) from baseline to 3 and 12 months postoperatively. The nominal data were compared via the χ² test, while the continuous data were compared via Student's t-test.

Results

The two groups had no difference regarding either the 3- or 12-month Euro-Qol-5D (EQ-5D), numeric rating scale (NRS) leg pain, and NRS back pain; however, the Tritanium interbody cage group had better Oswestry Disability Index (ODI) scores compared to the control group of the PEEK interbody cage at both 3 and 12 months (p=0.013 and 0.048).

Conclusions

Our results indicate the Tritanium cage is an effective alternative to the previously used PEEK cage in terms of PROs, surgical safety, and radiological parameters of surgical success. The Tritanium cohort showed better ODI scores, higher fusion rates, lower subsidence, and lower indirect costs associated with surgical management, when compared to the propensity-matched PEEK cohort.

Bone-Mounted Robotic System in Minimally Invasive Spinal Surgery for Osteoporosis Patients: Clinical and Radiological Outcomes

Purpose

Severe complications, including screw loosening events and low fusion rates, in spinal fusion surgery using the traditional open method are problematic. This retrospective study aimed to evaluate the rate of screw loosening and the clinical outcomes of bone-mounted miniature robot-assisted pedicle screw placement in patients treated for degenerative spinal disease.

Patients and Methods

Data were collected from the medical records of 118 patients (mean age, 69 years). Differences in clinical outcomes, including the Oswestry disability index, visual analog scale score, screw loosening rate, cage fusion rate, and complications, were evaluated among different bone mineral densities.

Results

The screw loosening and cage fusion rates for all patients, normal bone mineral density, osteopenia, and osteoporosis groups were 12%, 8.6%, 13.1%, and 14%, respectively, and 85.3%, 93%, 82.5%, and 81.4%, respectively. There was a higher screw loosening rate and a lower cage fusion rate in the osteopenia and osteoporosis groups than in the normal bone density group. The accuracy of the screw placement was 97.3%. There were no statistically significant differences in the Oswestry disability index and visual analog scale scores, and no major complications for dural tear or vascular or visceral injury.

Conclusion

Our study demonstrated an acceptable screw loosening rate in patients with osteoporosis compared to that in patients with normal bone mineral density. The robotic system resulted in accurate screw placement in patients with osteoporosis.

Local bone metabolism during the consolidation process of spinal interbody fusion

INTRODUCTION

Although computed tomography (CT) can identify the presence of eventual bony bridges following lumbar interbody fusion (LIF) surgery, it does not provide information on the ongoing formation process of new bony structures. ¹⁸F sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) could be used as complementary modality to add information on the bone metabolism at the fusion site. However, it remains unknown how bone metabolism in the operated segment changes early after surgery in uncompromised situations. This study aimed to quantify the changes in local bone metabolism during consolidation of LIF.

MATERIALS AND METHODS

Six skeletally mature sheep underwent LIF surgery. ¹⁸F-NaF PET/CT scanning was performed 6 and 12 weeks postoperatively to quantify the bone volume and metabolism in the operated segment. Bone metabolism was expressed as a function of bone volume.

RESULTS

Early in the fusion process, bone metabolism was increased at the endplates of the operated vertebrae. In a next phase, bone metabolism increased in the center of the interbody region, peaked, and declined to an equilibrium state. During the entire postoperative time period of 12 weeks, bone metabolism in the interbody region was higher than that of a reference site in the spinal column.

CONCLUSION

Following LIF surgery, there is a rapid increase in bone metabolism at the vertebral endplates that develops towards the center of the interbody region. Knowing the local bone metabolism during uncompromised consolidation of spinal interbody fusion might enable identification of impaired bone formation early after LIF surgery using ¹⁸F-NaF PET/CT scanning.

Safety and efficacy of stand-alone anterior lumbar interbody fusion in low-grade L5-S1 isthmic spondylolisthesis

Introduction

Surgical management of isthmic spondylolisthesis is controversial and reports on anterior approaches in the literature are scarce.

Research question

To evaluate the safety and efficacy of stand-alone anterior lumbar interbody fusion (ALIF) in patients with symptomatic low-grade L5-S1 isthmic spondylolisthesis.

Material and methods

All adult patients with isthmic spondylolisthesis of the lumbosacral junction treated in a single institution between 2008 and 2019 with stand-alone ALIF were screened. A titan cage was inserted at L5-S1 with vertebral anchoring screws. Prospectively collected surgical, clinical and radiographic data were analyzed retrospectively.

Results

34 patients (19 men, 15 women, mean age 52.5 ​± ​11.5 years) with a mean follow-up of 3.2 (±2.5) years were analyzed. 91.2% (n ​= ​31) of patients had a low-grade spondylolisthesis and 8.8% (n ​= ​3) grade III according to Meyerding classification. Mean COMI and ODI scores improved significantly from 6.9 (±1.5) and 35.5 (±13.0) to 2.0 (±2.5) and 10.2 (±13.0), respectively after one year, and to 1.7 (±2.5) and 8.2 (±9.6), respectively, after two years. The COMI and ODI scores improved in 86.4% and 80%, respectively, after one year and 92.9% of patients after two years by at least the minimal clinically important difference. No intraoperative complications were recorded. 8.8% (n ​= ​3) of patients needed a reoperation.

Discussion and conclusion

After stand-alone ALIF for symptomatic isthmic spondylolisthesis, the patients improved clinically important after one and two years. Stand-alone ALIF is a safe and effective surgical treatment option for low-grade isthmic spondylolisthesis.

•

Report of a series of patients with symptomatic low-grade L5-S1 isthmic spondylolisthesis treated by stand-alone ALIF.

•

Patient reported outcomes showed clinically important improvements after one and two years.

•

Stand-alone ALIF proved to be a safe and effective technique to treat symptomatic low-grade L5-S1 isthmic spondylolisthesis.

•

There were no vascular or other major complications.

Single-stage debridement via autogenous iliac bone graft through the OLIF corridor and lateral fixation in treating spontaneous single-level lumbar pyogenic spondylodiscitis

BACKGROUND

The aim of the present study was to investigate the efficacy and safety of mini-open oblique debridement and lumbar interbody fusion combined with lateral screw fixation for treating single-level pyogenic spondylodiscitis.

METHODS

Twelve patients with single-level lumbar pyogenic spondylodiscitis underwent OLIF combined with lateral screw fixation were analyzed. Patients underwent follow-up for 12 to 24 months. The clinical characteristics, etiological examinations, operative time, intraoperative blood loss, Oswestry Disability Index (ODI), visual analog scale score (VAS), postoperative complications, and the bony fusion rate were recorded.

RESULTS

The mean follow-up period of time was 14.8 months. The average operative time and intra-operative blood loss were 129.0 ± 19.76 min and 309.2 ± 92.96 mL, respectively. No severe intra-operative complications were observed during surgery, except in 1 case that develops abdominal pain and distension after surgery, 2 cases that develop left-sided transient thigh pain/numbness and 8 cases that complains of donor site (iliac crest) pain. All of these symptoms disappeared 8 weeks after surgery. Tissue sample cultures were obtained from all patients intraoperatively and four (33.3%) were positive, including 2 with Staphylococcus aureus, 1 with Staphylococcus epidermidis, and 1 with Escherichia coli. During an average of 22.5 ± 2.1 days (range, 14-29 days) after surgery, WBC, CPR, and ESR levels in all patients had returned to normal. All patients were pain free with no recurring infection. Solid bony fusions were observed in all cases within 6 months, including 10 with I grade fusion, 2 with II grade fusion according to the classification suggested by Burkus et al. No fixation failure was observed during follow up and solid bony fusions were observed in all 12 patients at finally follow-up. A significant postoperative increase was also observed in the mean segmental height and lordosis (P < 0.05), followed by a slight decrease of segmental height and lordosis at final follow-up. At the final follow up, the mean VAS (1.5 ± 0.6) and ODI (18.9 ± 7.6) were significantly lower than VAS (8.4 ± 2.7) and ODI (71.2 ± 16.5) before surgery (P < 0.01).

CONCLUSION

Single-stage debridement with autogenous iliac bone graft through the OLIF corridor and lateral fixation was a feasible surgical approach in our consecutive 12 cases of pyogenic spondylitis.

Improvements in lower-extremity patient-reported outcomes after lumbar interbody fusion

OBJECTIVE

Recently, new patient-reported outcome measures (PROMs) of the spine were designed to overcome the limitations of previous spinal PROMs and to consider the whole spine as a single kinetic functional unit. Owing to the significance of spine-hip-knee and global body balance, the spine and lower extremities cannot be considered separately. However, no reports have evaluated lower-extremity functional outcome using PROMs after lumbar spine surgery. The authors aimed to elucidate changes in hip and knee PROMs after lumbar interbody fusion and to evaluate the sagittal spinopelvic radiographic parameters that were most strongly correlated with lower-extremity PROMs.

METHODS

In 2018, the authors consecutively evaluated patients who underwent lumbar interbody fusion surgery with at most three levels. Preoperative and 1-year postoperative clinical and radiographic data were assessed. Spinal functional outcomes were measured with the Oswestry Disability Index (ODI), visual analog scale (VAS) for pain, and Scoliosis Research Society-22r (SRS-22r) questionnaire. Lower-extremity functional outcomes were evaluated with the Harris Hip Score (HHS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Linear regression was used to evaluate the relationship between spinal and lower-extremity PROMs and spinopelvic radiographic parameters.

RESULTS

The authors enrolled 67 patients, with a mean age of 66.4 years. The average number of surgical levels was 1.7. All assessed PROMs improved significantly after surgery (p < 0.001 for ODI, p < 0.001 for VAS, p = 0.017 for SRS-22r, p = 0.042 for HHS, and p = 0.033 for WOMAC). Spinopelvic parameters, including lumbar lordosis (LL), pelvic tilt (PT), C7 sagittal vertical axis, and sagittal radiographic parameters of hip and knee, significantly improved after surgery. On linear regression analysis, HHS and WOMAC correlated with LL and PT, respectively (β = 0.554 and p = 0.043 for correlation of HHS with LL; β = 1.573 and p = 0.021 for correlation of WOMAC with PT).

CONCLUSIONS

The current study demonstrated that lumbar fusion surgery may induce postoperative improvements in lower-extremity functional and radiological outcomes. However, among radiographic parameters, changes in LL and PT were the most strongly associated with lower-extremity PROMs.

Best versus worst surgical outcomes after single-level posterior lumbar interbody fusion for degenerative spondylolisthesis

PURPOSE

Previous studies have shown conflicting results regarding the factors affecting the clinical outcome after fusion for degenerative spondylolisthesis. However, no study has compared the best and worst clinical outcome groups using patient-reported outcome measures. We aimed to compare the characteristics of patients with best and worst outcomes following single-level lumbar fusion for degenerative spondylolisthesis.

METHODS

200 patients underwent single-level interbody fusion with a minimum 2-years follow-up were included. We excluded patients with surgical complications already-known to be associated with poor postoperative outcomes, including pseudoarthrosis and postoperative infection. According to 2-year postoperative Oswestry disability index scores, patients were divided into two groups; Best and Worst. Demographic, clinical and radiographic variables were compared between the two groups.

RESULTS

Compared with patients in the Best group, those in the Worst group were older (59.5 and 67.0 years, respectively; p = 0.012; odds ratio [OR], 1.143; 95% confidence interval [CI], 1.030-1.269) and had a longer duration of pain from onset (2.6 and 7.2 years, respectively; p = 0.041; OR, 1.021; 95% CI, 1.001-1.041). The cutoff value of pain duration from onset was measured as ≥3.5 years on Receiver operating characteristic analysis. Patients in the Worst group had a lower preoperative angular motion compared to those in the Best group (12.7° and 8.3°, respectively; p = 0.016; OR, 0.816; 95% CI, 0.691-0.963).

CONCLUSIONS

Degenerative spondylolisthesis patients of good clinical outcome after single-level lumbar interbody fusion were relatively young, had a short symptom duration before surgery, and a high preoperative instability compared with the patient having poor postoperative clinical outcome. Therefore, these findings should be considered preoperatively when deciding the appropriate individual treatment plan.

Two-year results of a double-blind multicenter randomized controlled non-inferiority trial of polyetheretherketone (PEEK) versus silicon nitride spinal fusion cages in patients with symptomatic degenerative lumbar disc disorders

Background

During lumbar spinal fusion, spacer cages are implanted to provide vertebral stability, restore sagittal alignment, and maintain disc and foraminal height. Polyetheretherketone (PEEK) is commonly used by most spine surgeons. Silicon nitride (Si₃N₄) is a less well-known alternative although it was first used as a spacer in lumbar fusion over 30 years ago. The present study was designed to see if Si₃N₄ cages would perform similarly to PEEK in a randomized controlled trial.

Methods

A non-inferiority multicenter 100-patient study was designed where both the observer and patient were blinded. Single- or double-level transforaminal lumbar interbody fusion with pedicle screw fixation using an oblique PEEK or Si₃N₄ cage was performed. The primary non-inferiority outcome was the Roland-Morris Disability Questionnaire (RMDQ). Secondary measures included the Oswestry Disability Questionnaire, Visual Analogue Scales (VAS) for back and leg pain, SF-36 Physical and Mental Function indices, patient and surgeon Likert scores on perceived recovery, and X-ray and CT radiological evaluations for subsidence, segmental motion, and fusion. Follow-up evaluations occurred at 3, 6, 12, and 24 months.

Results

After exclusions for protocol violations and canceled surgeries, 92 patients were randomized (i.e., 48 for PEEK and 44 for Si₃N₄). There were no differences in baseline demographics, pre-operative disabilities, or pain scores between the groups. Both treatment arms showed significant improvements in disability, pain, and recovery scores. No significant differences were observed for subsidence, segmental motion, or fusion. For the primary outcome (i.e., RMDQ scores), the non-inferiority of Si₃N₄ compared to PEEK could not be established using the original protocol criteria. However, the comparison was undermined by larger than anticipated patient fallout coupled with higher than expected RMDQ score standard deviations. A post hoc analysis coupled with a more extensive review of the literature was conducted which resulted in the selection of a revised clinically justified non-inferiority margin; and using this method, the non-inferiority of Si₃N₄ was affirmed.

Conclusions

This study demonstrated that the use of either PEEK or Si₃N₄ cages is safe and effective for patients undergoing lumbar spine fusion for chronic degenerative disc disease.

Porous titanium cervical interbody fusion device in the treatment of degenerative cervical radiculopathy; 1-year results of a prospective controlled trial

BACKGROUND CONTEXT

Anterior cervical discectomy with an interbody cage (ACDF) to obtain fusion is a common procedure in cervical spine surgery. Presently, polyetheretherketone (PEEK) with (auto) graft is frequently used for interbody fusion although alternative implant technology like 3-D printing titanium has been introduced recently.

PURPOSE

Reporting the clinical and quantitative radiological outcome of a prospective cohort of 3-D printed porous titanium implants.

STUDY DESIGN/SETTING

Prospective study of patients with single level ACDF using 3-D printed porous titanium cervical implants. These data were compared with 48 patients from the PEEK with autograft group of the previously performed CAncellous Structured Ceramic Arthrodesis DEvice trial.

PATIENT SAMPLE

Fourty-nine patients were included.

OUTCOME MEASURES

Neck disability index (NDI), visual analog scale (VAS), self-reported perceived recovery, and fusion status.

METHODS

The clinical outcomes and fusion rates were documented at 3, 6, and 12 months. Dynamic X-rays were analyzed to determine range of motion (ROM) of the operated level. Fusion was defined as rotation ≤4° and ≤1.25 mm translation on flexion-extension films.

RESULTS

The mean NDI improved from 41.2 preoperatively to 19.4 at 12 months postoperatively. Both VAS arm and VAS neck improved significantly after surgery and 77.1% of the patients reported complete or nearly complete recovery at 12 months. The mean ROM of the affected disc level decreased from 8.7° (range 2.6-21.4) before surgery to 1.6° (0.0-4.6°) after 12 months. The fusion rate at 3, 6, and 12 months was 84%, 89%, and 91% respectively, compared with 67%, 72%, and 90%, in the PEEK group.

CONCLUSIONS

3-D printed porous titanium cervical implants resulted in significant clinical improvement after surgery. The fusion rate of porous titanium compared with PEEK with autograft at 12 months was similar, although porous titanium resulted in faster consolidation. In addition, one level anterior cervical fusion can be successfully achieved without additional plating.

Comparative Clinical Effectiveness and Safety of Bone Morphogenetic Protein Versus Autologous Iliac Crest Bone Graft in Lumbar Fusion: A Meta-analysis and Systematic Review

STUDY DESIGN

This is a systematic literature review and meta-analysis.

OBJECTIVE

We aimed to evaluate the efficacy and safety of recombinant human bone morphogenetic protein (RhBMP) and autologous iliac crest bone graft (ICBG) in lumbar fusion.

SUMMARY OF BACKGROUND DATA

RhBMP has been emphasized in lumbar fusion due to high fusion success rate. However, ICBG remains the criterion standard graft approach for lumbar fusion. The safety and effectiveness of rhBMP are controversial.

METHODS

Prospective randomized controlled trials were searched from PubMed, EMBASE, and Cochrane Central Register of Controlled Trails by using Medical Subject Headings terms "bone morphogenetic protein,' "bone transplantation,' and "spinal fusion.' Two independent investigators screened eligible studies, assessed the bias of original articles, extracted data including fusion success, Oswestry disability index improvement, improved short form 36 questionnaire scores, adverse events and re-operation, and a subgroup analysis. The GRADE approach was used to grade quality of evidence.

RESULTS

Twenty randomized controlled trials (2185 patients) met the inclusion criteria. There were higher fusion success rate (odds ratio [OR] 3.79, 95% confidence interval [CI] 1.88-7.63, P = 0.0002), better improvement of Oswestry Disability Index (mean difference 1.54, 95% CI 0.18-2.89, P = 0.03), and lower re-operation rate (OR 0.59, 95% CI 0.43-0.80, P = 0.0007) in rhBMP group. Heterogeneity was obvious in fusion success rate (I = 58%); hence, a subgroup analysis, based on protein type (rhBMP-2 or rhBMP-7), was performed, which suggested that only rhBMP-2 was better than ICBG for lumbar fusion. There was no difference in the incidence of adverse events between rhBMP and ICBG (OR 0.91, 95% CI 0.70-1.18, P = 0.47).

CONCLUSION

In lumbar fusion, rhBMP-2 exhibited a higher fusion success rate and reduced the risk of re-operation. No difference in complication rate is between rhBMP (rhBMP-2 and rhBMP-7) and ICBG. We suggest rhBMP especially rhBMP-2 as an effective substitute for ICBG for lumbar fusion.

LEVEL OF EVIDENCE

1.

Role of MRI in the assessment of interbody fusion with tantalum intervertebral implant

INTRODUCTION

Radiologic assessment of interbody fusion (IF) is controversial; thin-slice CT is the present gold standard despite artifacts due to the metal implant that hinder interpretation. The present study aimed to assess the contribution of MRI in IF assessment after instrumented posterior lumbar interbody fusion (PLIF) using tantalum intervertebral implants. The study hypothesis was that fusion following PLIF can be assessed on MRI.

MATERIALS AND METHOD

A single-center retrospective study included 52 single-level PLIF procedures (42 for degenerative disc disease and 10 for isthmic spondylolisthesis) using 2 tantalum intervertebral cages without interbody bone graft. Fusion was assessed at 1 year on static and dynamic X-ray and on MRI with a dedicated protocol. Two senior osteoarticular radiologists screened frontal and sagittal MRI slices for continuous cancellous interbody bridges. Consolidation was considered acquired (grade I) in case of continuous bridges on at least 2 successive frontal or sagittal slices, possible (grade II) in case of continuous bridge on just 1 slice, or absent (grade III) in case of no or discontinuous bridge.

RESULTS

Forty-eight patients were included, with a mean 55 months' follow-up (range, 25-74 months). There were no hardware failures. Intervertebral mobility on dynamic X-ray was systematically less than 5°. Fusion on MRI was grade I in 71% of cases, grade II in 8% and grade III in 21%. Interobserver agreement was 100% on X-ray and 81% on MRI, with kappa coefficient=0.56 (range, 0.35-0.77).

DISCUSSION

Tantalum implants without bone autograft enabled satisfactory standard radiographic study. MRI provided imperfect assessment of fusion, being contributive only in case of positive findings (71% in the present study); when no bridge is detected on MRI, no conclusion can be drawn. Progress in CT to reduce artifacts may improve fusion assessment, unless bone integration on both sides of the implant is considered to be sufficient for interbody continuity, without a continuous bone bridge between endplates being a requirement.

LEVEL OF EVIDENCE

IV.

Clinical and radiographic analysis of unilateral versus bilateral instrumented one-level lateral lumbar interbody fusion

Lateral lumbar interbody fusion (LLIF) is a widely applied and useful procedure for spinal surgeries. However, posterior fixation has not yet been decided. We compared the radiographic and clinical outcomes of unilateral versus bilateral instrumented one-level LLIF for degenerative lumbar disease. We conducted a prospective cohort study of 100 patients, who underwent unilateral (group U) or bilateral (group B) instrumented one-level LLIF for degenerative lumbar disease. Forty-one patients in group U were undergoing unilateral pedicle screw instrumentation, and 59 patients in group B were undergoing bilateral pedicle screw instrumentation. Clinical characteristic and demographic data before surgery were compared. The intraoperative data, including operative time with changes in positions, intraoperative blood loss, and X-ray exposure time, as well as the perioperative data, including postoperative hospital stay and clinical and radiographic data were compared. As a result, Group U required a significantly shorter operating time than group B. The subsidence grade and fusion rates exhibited no significant differences in the postoperative radiographic evaluation. Group U had better results in clinical assessments than group B. However, group U required more additional surgeries owing to complications.

Prospective Evaluation of Spino-Pelvic Parameters with Clinical Correlation in Patients Operated with an Anterior Lumbar Interbody Fusion

Study Design

Prospective study.

Purpose

The goal of this study was to evaluate the impact of anterior lumbar interbody fusion (ALIF) on L5–S1 level for restitution of distal segmental lordosis and to investigate its consequences on spino-pelvic parameters and the global sagittal balance.

Overview of Literature

Lumbar surgery must be adapted to the spinal morphology in order to restore an adequate relation between pelvic and spinal parameters and especially to the pelvic incidence.

Methods

An observational, prospective study was conducted between January 2013 and May 2017. Eighty-six patients were treated by L5–S1 ALIF procedure regardless of disc replacement above L5–S1 level. Thirty-seven patients were included and subset analyses were performed on 25 patients operated on an isolated ALIF L5–S1 (group 1), and 12 patients with hybrid surgery consisting of an L5– S1 ALIF procedure and a L4–L5 lumbar disc replacement (group 2). Clinical parameters were analyzed using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) at M0 (preoperative) and M12 (12 months). Lumbo-pelvic parameters were assessed on a standingfull-spine X-ray, preoperatively and at M12 after surgery.

Results

We observed a significant evolution of L1–S1 lumbar lordosis (p <0.001) with a significant increase of the distal arch L4–S1 lordosis (p <0.001) and decrease of the proximal arch lordosis (p =0.03). Preoperatively, 27% of the patients were unbalanced. Significant variation in sagittal balance parameters was observed, with a decrease of the sagittal vertebral axis (p <0.001). VAS and ODI improved significantly but no correlation was found. An evolution in the same direction was found in the two subgroup analyses.

Conclusions

ALIF procedure on L5–S1 level allowed a reconstruction of lumbosacral segmental lordosis, modification of global lordosis, without variation of spino-pelvic parameters except an improvement in sagittal balance.

Clinical evaluation of a bone cement-injectable cannulated pedicle screw augmented with polymethylmethacrylate: 128 osteoporotic patients with 42 months of follow-up

OBJECTIVES

To evaluate the safety and efficacy of a novel bone cement-injectable cannulated pedicle screw augmented with polymethylmethacrylate in osteoporotic spinal surgery.

METHODS

This study included 128 patients with osteoporosis (BMD T-score -3.2±1.9; range, -5.4 to -2.5) who underwent spinal decompression and instrumentation with a polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screw. Postoperative Visual Analogue Scale scores and the Oswestry Disability Index were compared with preoperative values. Postoperative plain radiographs and computed tomography (CT) scans were performed immediately after surgery; at 1, 3, 6, and 12 months; and annually thereafter.

RESULTS

The mean follow-up time was 42.4±13.4 months (range, 23 to 71 months). A total of 418 polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screws were used. Cement extravasations were detected in 27 bone cement-injectable cannulated pedicle screws (6.46%), mainly in cases of vertebral fracture, without any clinical sequela. The postoperative low back and lower limb Visual Analogue Scale scores were significantly reduced compared with the preoperative scores (<0.01), and similar results were noted for the Oswestry Disability Index score (p<0.01). No significant screw migration was noted at the final follow-up relative to immediately after surgery (p<0.01). All cases achieved successful bone fusion, and no case required revision. No infection or blood clots occurred after surgery.

CONCLUSIONS

The polymethylmethacrylate-augmented bone cement-injectable cannulated pedicle screw is safe and effective for use in osteoporotic patients who require spinal instrumentation.

Fusion Assessment by MRI in Comparison With CT in Anterior Lumbar Interbody Fusion: A Prospective Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To evaluate the role of magnetic resonance imaging (MRI) in evaluation of fusion status following anterior lumbar interbody fusion (ALIF) and compare agreement and confidence in assessing fusion or its absence on MRI to the current standard computed tomography (CT).

METHODS

A prospective follow up of patients undergoing surgery by 2 spine surgeons between 2012 and 2015 at a single institution. Fusion was assessed at different time points in these patients by 2 independent musculoskeletal radiologists. Fusion was analyzed in coronal and sagittal planes using both imaging modalities, with confidence being attributed on a scale of 0 to 3. Assessors were blinded to patient data.

RESULTS

Fourteen patients (25 levels) with mean follow-up of 10.2 months (range 2.4-20.3 years) and age of 41 years (range 20.7-61.5 years) were assessed. MRI within the interbody cage in coronal (κ = .58) and sagittal (κ = .50) planes had the highest interobserver agreement. CT anterior to the cage in coronal (κ = .48) and sagittal (κ = .44) planes, as well as within the cage in coronal (κ = .50) and sagittal planes (κ = .44) showed moderate agreement. Confidence anterior to the interbody cage using MRI scan was reduced when compared with remaining angles and imaging modalities.

CONCLUSIONS

The study demonstrates that MRI may be a useful tool in the assessment of fusion following ALIF with results comparable to CT, and that it may have a useful role in select patients especially considering marked radiation exposure reduction.

Comparison of polyetheretherketone versus silicon nitride intervertebral spinal spacers in a caprine model

Polyetheretherketone (PEEK) is commonly used as a spinal spacer for intervertebral fusion surgery. Unfortunately, PEEK is bioinert and does not effectively osseointegrate into living bone. In contrast, comparable spacers made of silicon nitride (Si₃ N₄ ) possess a surface nanostructure and chemistry that encourage appositional bone healing. This observational study was designed to compare the outcomes of these two biomaterials when implanted as spacers in an adult caprine model. Lumbar interbody fusion surgeries were performed at two adjacent levels in eight adult goats using implants of PEEK and Si₃ N₄ . At six-months after surgery, the operative and adjacent spinal segments were extracted and measured for bone fusion, bone volume, bone-implant contact (BIC) and soft-tissue implant contact (SIC) ratios, and biodynamic stability. The null hypothesis was that no differences in these parameters would be apparent between the two groups. Fusion was observed in seven of eight implants in each group with greater bone formation in the Si₃ N₄ group (52.6%) versus PEEK (27.9%; p = 0.2). There were no significant differences in BIC ratios between PEEK and Si₃ N₄ , and the biodynamic stability of the two groups was also comparable. The results suggest that Si₃ N₄ spacers are not inferior to PEEK and they may be more effective in promoting arthrodesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 688-699, 2019.

Load-sharing through elastic micro-motion accelerates bone formation and interbody fusion

BACKGROUND CONTEXT

Achieving a successful spinal fusion requires the proper biological and biomechanical environment. Optimizing load-sharing in the interbody space can enhance bone formation. For anterior cervical discectomy and fusion (ACDF), loading and motion are largely dictated by the stiffness of the plate, which can facilitate a balance between stability and load-sharing. The advantages of load-sharing may be substantial for patients with comorbidities and in multilevel procedures where pseudarthrosis rates are significant.

PURPOSE

We aimed to evaluate the efficacy of a novel elastically deformable, continuously load-sharing anterior cervical spinal plate for promotion of bone formation and interbody fusion relative to a translationally dynamic plate.

STUDY DESIGN/SETTING

An in vivo animal model was used to evaluate the effects of an elastically deformable spinal plate on bone formation and spine fusion.

METHODS

Fourteen goats underwent an ACDF and received either a translationally dynamic or elastically deformable plate. Animals were followed up until 18 weeks and were evaluated by plain x-ray, computed tomography scan, and undecalcified histology to evaluate the rate and quality of bone formation and interbody fusion.

RESULTS

Animals treated with the elastically deformable plate demonstrated statistically significantly superior early bone formation relative to the translationally dynamic plate. Trends in the data from 8 to 18 weeks postoperatively suggest that the elastically deformable implant enhanced bony bridging and fusion, but these enhancements were not statistically significant.

CONCLUSIONS

Load-sharing through elastic micro-motion accelerates bone formation in the challenging goat ACDF model. The elastically deformable implant used in this study may promote early bony bridging and increased rates of fusion, but future studies will be necessary to comprehensively characterize the advantages of load-sharing through micro-motion.

In vitro investigation of two connector types for continuous rod construct to extend lumbar spinal instrumentation

PURPOSE

Instrumentation of the lumbar spine is a common procedure for treating pathologic conditions. Studies have revealed the risks of pathologies in the adjacent segments, with the incidence rate being up to 36.1%. Revision procedures are often required, including extension of the instrumentation by the use of connectors to adjacent levels. The aim of this study was to determine the stiffness of side-to-side and end-to-end connectors for comparison with the use of continuous rods.

METHODS

Ten human lumbar spine specimens (L1-S1) were tested about the three axes under pure moment loading of ± 7.5 Nm. Nine conditions were used to investigate the functions of the extensions for different instrumentation lengths (L3-S1 and L2-S1) and different connector levels (L3/4 and L2/3). The intersegmental range of motion (iROM) and intersegmental neutral zone as well as total range of motion (tROM) and total neutral zone (tNZ) were analyzed.

RESULTS

The application of the spinal system significantly decreased the tROMs (- 44 to - 83%) and iROMs in levels L2/3 (- 56 to - 94%) and L3/4 (- 68 to - 99%) in all the tested directions, and the tNZ under flexion/extension (- 63 to - 71%) and axial rotation (- 34 to - 72%). These decreases were independent of the employed configuration (p < 0.05). The only significant changes in the iROM were observed under lateral bending between the continuous rod and the side-to-side connector at level L3/4 (p = 0.006).

CONCLUSION

From a biomechanical viewpoint, the tested connectors are comparable to continuous rods in terms of ROM and NZ. These slides can be retrieved under Electronic Supplementary Material.

Lumbar Spinous Process Fixation and Fusion: A Systematic Review and Critical Analysis of an Emerging Spinal Technology

STUDY DESIGN

A systematic review.

OBJECTIVE

The available literature on interspinous rigid fixation/fusion devices (IFD) was systematically reviewed to explore the devices' efficacy and complication profile.

SUMMARY OF BACKGROUND DATA

The clinical application of new spinal technologies may proceed without well-established evidence, as is the case with IFDs. IFDs are plate-like devices that are attached to the lateral aspects of 2 adjacent spinous processes to promote rigidity at that segment. Despite almost a decade since the devices' introduction, the literature regarding efficacy and safety is sparse. Complications have been reported but no definitive study is known to the authors.

METHODS

A systematic review of the past 10 years of English literature was conducted according to PRISMA guidelines. The timeframe was chosen based on publication of the first study containing a modern IFD, the SPIRE, in 2006. All PubMed publications containing MeSH headings or with title or abstract containing any combination of the words "interspinous," "spinous process," "fusion," "fixation," "plate," or "plating" were included. Exclusion criteria consisted of dynamic stabilization devices (X-Stop, DIAM, etc.), cervical spine, pediatrics, and animal models. The articles were blinded to author and journal, assigned a level of evidence by Oxford Centre of Evidence-Based Medicine (OCEBM) criteria, and summarized in an evidentiary table.

RESULTS

A total of 293 articles were found in the initial search, of which 15 remained after examination for exclusion criteria. No class I or class II evidence regarding IFDs was found. IFDs have been shown by methodologically flawed and highly biased class III evidence to reduce instability at 1 year, without statistical comparison of complication rates against other treatment modalities.

CONCLUSIONS

Although IFDs are heavily marketed and commonly applied in modern practice, data on safety and efficacy are inadequate. The paucity of evidence warrants reexamination of these devices' value and indications by the spine surgery community.

Perioperative Results and Complications after Posterior Lumbar Interbody Fusion for Spinal Stenosis in Geriatric Patients over than 70 Years Old

Objective

As increasing the size of the geriatric population, the number of elderly patients, who need the surgery for painful degenerative spinal stenosis has been increasing. The geriatric population may be relatively high complications, because of age and age-associated medical conditions. However, there is a lack of studies addressing the perioperative complications and outcomes in elderly patients with posterior lumbar inter body fusion with screw augmentation (PLIF).

Methods

We retrospectively reviewed the medical records and radiographic studies of geriatric patients who had spine surgery of PLIF due to spinal stenosis for 11 years. We divided into 2 groups (A; 70–75 years, B; over then 76 years) according to the age. Surgical level of each groups, hospital day and postoperative day, co-morbidities, complications, clinical outcomes were analyzed. Operative reports, hospital and outpatient clinic charts, and radiographic studies were reviewed.

Results

Group A was composed of 80 patients, their mean age was 72.21 and female dominant (n=46), and their mean surgically fused level was 1.52 level. Group B was 36 patients, their mean age was 78.83 and female dominant (n=20), and their mean surgically fused level was 1.36 level. Comparing between two groups, complications, postoperative hospital stay were slightly increase in group B and co-morbidity was statistically high in group B, however clinical outcomes were similar between two groups.

Conclusion

Increasing age might be an important risk factor for complications in patients undergoing PLIF, however, we would like to recommend that if the situation of spine of extreme geriatric patients need PLIF, it should be in the surgeon’s consideration after careful selection and clinical judgement.

Interobserver and Intraobserver Reliability in the Radiologic Assessment of Lumbar Interbody Fusion

STUDY DESIGN

Retrospective cohort study comparing intraobserver and interobserver reliability of 3 different radiologic fusion classifications following uninstrumented single-level anterior lumbar interbody fusion.

OBJECTIVE OF THE STUDY

The objective of the study was to compare the intraobserver and interobserver reliability of 3 different radiologic spinal fusion scoring systems.

SUMMARY OF BACKGROUND DATA

Knowledge regarding radiologic spinal fusion is crucial when studying patients that were treated with lumbar interbody fusion. The scoring system should be reliable and reproducible. Various radiologic classification systems coexist, but the reliability of these systems has thus far not been compared in a single consecutive group of patients. The aim of the present study was the identification of the most valid scoring system in the assessment of interbody fusion.

METHODS

We studied a retrospective consecutive cohort of 50 patients who underwent an anterior lumbar interbody fusion procedure by a single surgeon using a stand-alone cage performed between 1993 and 2002. Plain anterior-posterior, lateral radiographs, and flexion-extension radiographs were made during follow-up visits and were used for analysis. The interbody fusion was scored on these radiographic images using the 3 classification systems (Brantigan, Burkus, and the Radiographic Score) by 2 experienced musculoskeletal radiologists and 2 senior orthopedic spinal surgeons all of whom were blinded to clinical data and outcome.

RESULTS

Of the 3 classifications included in the current study, the Burkus classification had a moderate interobserver agreement and a substantial to perfect intraobserver agreement. The other classifications (Bratingan and the Radiographic Score) showed only fair interobserver agreement and moderate to substantial agreement among all observers. No significant differences in reliability between orthopedic surgeons and radiologists were found for all 3 classifications.

CONCLUSIONS

The Burkus classification system was classified as most reliable in this, but showed only moderate interobserver agreement. Therefore, the need for a more reliable classification system for the radiographic assessment of lumbar interbody fusion still exists to date.

[A continuous series of 27 adult patients treated for L5-S1 isthmic spondylolisthesis by combined approach: Clinical and radiological outcomes at 1 year follow-up]

Through this single-center consecutive prospective study, we evaluated the results of a combined approach for L5-S1 isthmic spondylolisthesis, using a polyetheretherketone (PEEK) interbody lordotic cage during anterior approach and pedicle screw-based posterior fixation. Between 2010 and 2014, 27 adult patients were treated for L5-S1 isthmic spondylolisthesis (high and low grades) by a combined approach with a minimum follow-up of one year. Clinical outcome was assessed before surgical treatment and at four months and one year after surgery by: VAS, Oswestry Index (ODI) and Rolland-Morris scores. Two observers evaluated the following radiological parameters: pelvic incidence, pelvic tilt, lumbar lordosis, segmental lordosis L5-S1, anterior and posterior disc height, spinal vertical axis (SVA), SVA/sacro-femoral distance (SFD) ratio. Fusion was evaluated on the CT scan at one-year follow-up. Blood loss, surgery time and complications were also collected. The mean age was 47.7 years (±16.9). The VAS, ODI and Rolland-Morris scores were significantly improved postoperatively, decreased from 7.5 (±1.45); 48 (±19.25); 15.3 (±4.67) before the surgery to 3.8 (±2.55); 28.7 (±19.58) and 7.76 (±7.21) respectively at one year after the surgery (P=0.05). The mean follow-up was 3.3 years. Mean surgery time was 193.7min (±37). Fusion was obtained in 100% of cases. Segmental lordosis L5-S1, pelvic tilt, slippage, anterior and posterior L5-S1 disc height were significantly improved postoperatively, they passed from 20.1; 22.6; 35.3%; 26.4%; 17.9% to 29.5; 20.6; 20.3%; 64.4%; 36.3% respectively. Combined surgical procedure meets the required goals of surgery in the treatment of adults L5-S1 isthmic spondylolisthesis.

Does partial coating with titanium improve the radiographic fusion rate of empty PEEK cages in cervical spine surgery? A comparative analysis of clinical data

BACKGROUND

Anterior cervical diskectomy and fusion (ACDF) is a well-established surgical treatment. Several types of intervertebral spacers can be used, but there is increasing evidence that PEEK cages yield insufficient fusion and thus less clinical improvement. The study aim was to assess the outcomes of single-level ACDF with an empty PEEK cage partially coated with titanium.

METHODS

This prospective multicenter single-arm clinical study collected follow-up data at 6, 12, and 18 months. A post hoc comparison was made to closely matched patients from another similar trial treated with identically designed, empty, uncoated PEEK cages.

RESULTS

There were 49 of 50 patients (98%) who met the MCID of 3+ points of improvement on VAS pain or had an 18-month VAS ≤ 1. Yet even by 18 months post-op, only 40 of 50 (80%) PEEK + Ti patients achieved complete bony fusion. The PEEK + Ti group (n = 49) seemed to have somewhat better fusion scores and significantly better pain relief at 6 M than the matched controls (n = 49), but these differences did not persist at 12 M or 18 M. Patients (with either implant) who achieved complete bony fusion had significantly better improvement of pain at 6 M and disability at 6 M and 12 M than patients that remained unfused.

CONCLUSIONS

ACDF is effective treatment for cervical myelopathy and radiculopathy. Although this and other studies show that titanium fuses better, partial coating of a PEEK cage does not improve the fusion rate sufficiently or confer other lasting clinical benefit. PEEK cages fully coated with titanium should be tested in prospective randomized comparative trials.

TRIAL REGISTRATION

Prospective, multicenter, single-arm clinical observational study without an individual Trial registration number. Study design and post hoc data analysis according to the "PIERCE-PEEK study", ISRCTN42774128, retrospectively registered 14 April 2009.

Empty polyetheretherketone (PEEK) cages in anterior cervical diskectomy and fusion (ACDF) show slow radiographic fusion that reduces clinical improvement: results from the prospective multicenter "PIERCE-PEEK" study

Background

Anterior cervical diskectomy and fusion (ACDF) is a well-established surgical treatment for radiculopathy and myelopathy. Previous studies showed that empty PEEK cages have lower radiographic fusion rates, but the clinical relevance remains unclear. This paper’s aim is to provide high-quality evidence on the outcomes of ACDF with empty PEEK cages and on the relevance of radiographic fusion for clinical outcomes.

Methods

This large prospective multicenter clinical trial performed single-level ACDF with empty PEEK cages on patients with cervical radiculopathy or myelopathy. The main clinical outcomes were VAS (0–10) for pain and NDI (0–100) for functioning. Radiographic fusion was evaluated by two investigators for three different aspects.

Results

The median (range) improvement of the VAS pain score was: 3 (1–6) at 6 months, 3 (2–8) at 12 months, and 4 (2–8) at 18 months. The median (range) improvement of the NDI score was: 12 (2–34) at 6 months, 18 (4–46) at 12 months, and 22 (2–44) at 18 months. Complete radiographic fusion was reached by 126 patients (43%) at 6 months, 214 patients (73%) at 12 months, and 241 patients (83%) at 18 months. Radiographic fusion was a highly significant (p < 0.001) predictor of the improvement of VAS and NDI scores.

Conclusion

This study provides strong evidence that ACDF is effective treatment, but the overall rate of radiographic fusion with empty PEEK cages is slow and insufficient. Lack of complete radiographic fusion leads to less improvement of pain and disability. We recommend against using empty uncoated pure PEEK cages in ACDF.

Trial registration

ISRCTN42774128. Retrospectively registered 14 April 2009.

PEEK Cages in Lumbar Fusion: Mid-term Clinical Outcome and Radiologic Fusion

STUDY DESIGN

Historical cohort analysis.

OBJECTIVE

Evaluation of mid-term clinical outcome and radiologic fusion in patients treated with a polyetheretherketone (PEEK) cage.

SUMMARY OF BACKGROUND DATA

Anterior lumbar interbody fusion can be a good alternative in chronic low back pain when conservative treatment fails. Although titanium alloy cages give good fusion rates, disadvantages are the subsidence of the cage in the adjacent vertebrae and problematic radiologic evaluation of fusion. PEEK cages such as the Synfix-LR cage (Synthes, Switzerland) should overcome this.

METHODS

From December 2004 until August 2007, 95 patients (21 double-level and 74 single-level) with degenerative disk disease from L3-S1 were operated by a single surgeon. The number of reoperations was counted. Radiologic fusion on computed tomography scan was scored with a new scoring system by an independent skeletal radiologist and orthopedic surgeon. Intraobserver agreement and specificity were assessed. Clinical improvement was measured by the Oswestry Disability Index score. The median duration of clinical follow-up was 47.7 months (range 29.9-61.6).

RESULTS

In total, 26 patients were reoperated after a median period of 17.6 months (range 6.7-46.9) of the initial surgery. Of the 26 patients, 23 patients (18 single-level and 5 double-level) were reoperated for symptomatic pseudarthrosis. A moderate agreement (κ=0.36) and a specificity of 70% and 37% for the radiologist and orthopedic surgeon, respectively, were found for scoring bony bridging. The Oswestry Disability Index score improved after initial surgery; however, reoperated patients reported a significantly lower improvement.

CONCLUSIONS

A high number of reoperations after an anterior lumbar interbody fusion procedure with the Synfix-LR cage were found, mainly because of symptomatic pseudarthrosis. The absence of posterior fixation in combination with lower stiffness and the hydrophobic characteristics of PEEK probably lead to insufficient initial stability, creating suboptimal conditions for bony bridging, and thus solid fusion. The proposed ease of the evaluation of radiologic fusion could not be supported. Clinicians should be alert on pseudarthrosis when patients treated with the Synfix-LR cage presented with persisted or aggravated complaints.

Prospective Clinical and Radiographic Results of Activ L Total Disk Replacement at 1- to 3-Year Follow-up

STUDY DESIGN

A prospective clinical study.

OBJECTIVE

To assess the clinical and radiographic results of activ L total disk replacement (TDR) on degenerative disk diseases.

SUMMARY OF BACKGROUND DATA

There are few reports on Activ L TDR, and this is the first in China.

MATERIALS AND METHODS

From March 2009 to March 2012, 32 patients with degenerative disk disease underwent either monosegmental or bisegmental lumbar TDR, which was documented in a prospective observational mode. Clinical success was defined as disability [Oswestry Disability Index (ODI)] improvement of at least 15 points versus baseline, no device failure, no major complications, no neurological deterioration. Additional clinical parameters as Visual Analogue Scale and Oswestry Disability Index (ODI) were evaluated preoperatively and postoperatively (1, 2, and 3 y). Radiographic parameters as range of motion (ROM) and intervertebral disk height (IDH) of the index and adjacent segments were also carried out. Prosthesis subsidence and heterotopic ossification were observed during the follow-up period. Work status was tracked for all patients.

RESULTS

Overall, 30 patients (93.7%) were available for a mean follow-up of 28.8 months (12-46 mo) and had complete radiographic data. Their mean age was 45.1 years (32-58 y). At 3 years postoperatively, the success rate was 86.7% (26/30). After surgery, clinical parameters as Visual Analogue Scale score for back and leg pain, and ODI score showed statistically significant improvement (P<0.001), and the situation was well maintained during the follow-up time points. At 3 years postoperatively, the mean IDH at the index segment and upper and lower adjacent segments were 12.87, 12.61, and 11.62 mm, respectively, showing no significant difference compared with preoperative data (P1=0.0597, P2=0.6669, P3=0.9813). The ROM of the index and upper adjacent segment showed a slight but significant increase at the 3-year follow-up compared with baseline (P1=0.0128, P2=0.0007). The changes of ROM at the lower adjacent segment were not significant (P=0.6637). Tears of the iliac vein were observed in 2 patients. Prosthesis subsidence was observed in 3 patients (1 at 12 mo postoperatively, 1 at 24 mo postoperatively, and 1 at 32 mo postoperatively). Heterotopic ossification was observed in 1 patient at 36 mo postoperatively. At the 3-year follow-up, only 8 patients went back to their original work, and 15 patients changed jobs, whereas the last 7 patients stopped working.

CONCLUSIONS

The 1- to 3-year follow-up of this cohort of patients showed satisfactory clinical outcomes. The IDHs at index and adjacent segments were well maintained after the surgery. The ROM at the lower adjacent segment remained unchanged, but the ROM at the index and upper adjacent segments showed a slight increase. The long-term results of activ L TDR was to be investigated.

Do Trunk Muscles Affect the Lumbar Interbody Fusion Rate?: Correlation of Trunk Muscle Cross Sectional Area and Fusion Rates after Posterior Lumbar Interbody Fusion Using Stand-Alone Cage

Objective

Although trunk muscles in the lumbar spine preserve spinal stability and motility, little is known about the relationship between trunk muscles and spinal fusion rate. The aim of the present study is to evaluate the correlation between trunk muscles cross sectional area (MCSA) and fusion rate after posterior lumbar interbody fusion (PLIF) using stand-alone cages.

Methods

A total of 89 adult patients with degenerative lumbar disease who were performed PLIF using stand-alone cages at L4–5 were included in this study. The cross-sectional area of the psoas major (PS), erector spinae (ES), and multifidus (MF) muscles were quantitatively evaluated by preoperative lumbar magnetic resonance imaging at the L3–4, L4–5, and L5–S1 segments, and bone union was evaluated by dynamic lumbar X-rays.

Results

Of the 89 patients, 68 had bone union and 21 did not. The MCSAs at all segments in both groups were significantly different (p<0.05) for the PS muscle, those at L3–4 and L4–5 segments between groups were significantly different (p=0.048, 0.021) for the ES and MF muscles. In the multivariate analysis, differences in the PS MCSA at the L4–5 and L5–S1 segments remained significant (p=0.048, 0.043 and odds ratio=1.098, 1.169). In comparison analysis between male and female patients, most MCSAs of male patients were larger than female's. Fusion rates of male patients (80.7%) were higher than female's (68.8%), too.

Conclusion

For PLIF surgery, PS muscle function appears to be an important factor for bone union and preventing back muscle injury is essential for better fusion rate.

Anterior approach with expandable cage implantation in management of unstable thoracolumbar fractures: Results of a series of 93 patients

INTRODUCTION

Anterior approach indications in unstable thoracolumbar fractures (UTLF) are debated. The aim of this study was to evaluate the results of anterior fixation and expandable prosthetic vertebral body cage (EPVBC) implantation alone or combined with a posterior approach in the management of UTLF.

MATERIALS AND METHODS

Ninety-three patients underwent anterior fixation with implantation of an EPVBC for UTLF from T7 to L5. Long-term kyphosis and vertebral height loss reduction, functional outcomes including visual analogical scale and Oswestry disability index were evaluated.

RESULTS

Anterior fixation led to a significant increase of vertebral body height with a gain of 13% after a previous posterior approach, 38% after a single anterior approach and 65% after combined posterior and anterior approaches (P=0.0001). However, anterior fixation did not significantly enhance the vertebral regional kyphosis angle (P=0.08), except in cases of single anterior approach for thoracic fractures (P=0.03). No significant difference was found between early, 3 months and 1 year postoperative vertebral regional kyphosis angle and vertebral body height (P=0.6). Complete fusion was routinely observed at 1 year postoperatively. rhBMP2 implantation in selected cases appears to be a safe and reliable strategy. No infections or surgical revisions were observed after the anterior approach.

CONCLUSION

Anterior approach and EPVBC implantation, in UTLF, is a safe and effective procedure, providing long-term vertebral body height and kyphosis correction. Adverse effects of anterior approach remain acceptable. Single anterior fixation is a reliable surgical alternative in thoracic fractures without posterior spine segment injury or spinal cord compression. These results prompted us to extend anterior approach indications in oncology and infectious diseases.

Radiographic Analysis of One-level Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF) With Unilateral Pedicle Screw Fixation for Lumbar Degenerative Diseases

STUDY DESIGN

A prospective randomized study was conducted.

OBJECTIVE

The purpose of this study was to assess the radiographic outcomes of one-level minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) with unilateral pedicle screw instrumentation for degenerative lumbar spine disease.

SUMMARY OF BACKGROUND DATA

MI-TLIF has become an increasingly popular method of lumbar arthrodesis. Recent technological advances in spinal instrumentation have culminated in the development of MI-TLIF with unilateral pedicle screw fixation. However, there are few published studies on radiographic outcomes of the MI-TLIF with unilateral pedicle screw fixation.

METHODS

A total of 65 patients with one-level degenerative lumbar spine disease were enrolled in this study. Patients were randomized into the unilateral or bilateral fixation group based on a computer-generated number list. Thirty-one patients (17 men and 14 women; average age, 57.3 y) were randomized to the unilateral group (group A) and 34 patients (16 men and 18 women; average age, 58.9 y) to the bilateral group (group B). All patients underwent minimally invasive decompression, interbody fusion, and pedicle screw fixation with the assistance of microscopic tubular retractor system (METRx-MD) and Sextant system. All patients were asked to follow-up at 3, 6, and thereafter once every 6 months after surgery. The visual analog scale (VAS), Oswestry disability index (ODI), and modified Prolo (mProlo) scores were obtained for all patients 24 hours before the operation and at each follow-up visit. The whole lumbar lordosis (WL), the segmental lordosis (SL), fusion level disk space angle, lumbar scoliosis angle, and segmental scoliosis angle were determined before and after surgery on standard x-rays. The disk height index (DI) and the lumber curvature index (LI) were also evaluated.

RESULTS

The mean follow-up was 26.6 months, with a range of 18-36 months. All patients showed evidence of fusion at 12 months postoperatively. Statistically, there was no significant difference between the 2 groups in terms of demographic data. The average postoperative VAS, ODI, and mProlo scores improved significantly in each group. No significant differences were found between the 2 groups in relation to VAS, ODI, and mProlo scores at each follow-up time point. There were no significant differences between the 2 groups in relation to WL, SL, disk space angle, lumbar scoliosis angle, segmental scoliosis angle, DI, and LI. There was also no difference between postoperative different follow-up visits in terms of these radiographic parameters in both groups. There was a positive linear correlation between the LI and WL in both groups.

CONCLUSIONS

One-level unilateral pedicle screw instrumented MI-TLIF provided similar radiologic and clinical outcomes to bilateral pedicle screw instrumented MI-TLIF. This study showed that MIS-TLIF with unilateral pedicle screw fixation would be sufficient in the management of preoperatively stable patients with lumbar degenerative disease.

Minimal Invasive Circumferential Management of Thoracolumbar Spine Fractures

Introduction. While thoracolumbar fractures are common lesions, no strong consensus is available at the moment. Objectives. The aim of this study was to evaluate the results of a minimal invasive strategy using percutaneous instrumentation and anterior approach in the management of thoracolumbar unstable fractures. Methods. 39 patients were included in this retrospective study. Radiologic evaluation was based on vertebral and regional kyphosis, vertebral body height restoration, and fusion rate. Clinical evaluation was based on Visual Analogic Score (VAS). All evaluations were done preoperatively and at 1-year follow-up. Results. Both vertebral and regional kyphoses were significantly improved on postoperative evaluation (13° and 7° versus −1° and −9°  P < 0.05, resp.) as well as vertebral body height (0.92 versus 1.16, P < 0.05). At 1-year follow-up, mean loss of correction was 1°. A solid fusion was visible in all the cases, and mean VAS was significantly reduced form 8/10 preoperatively to 1/10 at the last follow-up. Conclusion. Management of thoracolumbar fractures using percutaneous osteosynthesis and minimal invasive anterior approach (telescopic vertebral body prosthesis) is a valuable strategy. Results of this strategy offer satisfactory and stable results in time.

Sagittal plane lumbar intervertebral motion during seated flexion-extension radiographs of 658 asymptomatic nondegenerated levels

OBJECT

Evaluation of lumbar stability is fundamentally dependent on a clear understanding of normal lumbar motion. There are inconsistencies in reported lumbar motion across previously published studies, and it is unclear which provide the most reliable reference data. New technology now allows valid and reliable determination of normal lumbar intervertebral motion (IVM). The object of this study was to provide normative reference data for lumbar IVM and center of rotation (COR) using validated computer-assisted measurement tools.

METHODS

Sitting flexion-extension radiographs were obtained in 162 asymptomatic volunteers and then analyzed using a previously validated and widely used computerized image analysis method. Each lumbar level was subsequently classified as “degenerated” or “nondegenerated” using the Kellgren-Lawrence classification. Of the 803 levels analyzed, 658 were nondegenerated (Kellgren-Lawrence grade < 2). At each level of the lumbar spine, the magnitude of intervertebral rotation and translation, the ratio of translation per degree of rotation (TPDR), and the position of the COR were calculated in the nondegenerative cohort. Translations were calculated in millimeters and percentage endplate width.

RESULTS

All parameters were significantly dependent on the intervertebral level. The upper limit of the 95% CIs for anteroposterior intervertebral translation in this asymptomatic cohort ranged from 2.1 mm (6.2% endplate width) to 4.6 mm (13.3% endplate width). Intervertebral rotation upper limits ranged from 16.3° to 23.5°. The upper limits for TPDR ranged from 0.49% to 0.82% endplate width/degree. The COR coordinates were clustered in level-dependent patterns.

CONCLUSIONS

New normal values for IVM, COR, and the ratio of TPDR in asymptomatic nondegenerative lumbar levels are proposed, providing a reference for future interpretation of sagittal plane motion in the lumbar spine.

Polyetheretherketone (PEEK) cages in cervical applications: a systematic review

BACKGROUND CONTEXT

Polyetheretherketone (PEEK) cages have been widely used during the past decade in patients with degenerative disorders of the cervical spine. Their radiolucency and low elastic modulus make them attractive attributes for spinal fusion compared with titanium and bone graft. Still, limitations are seen such as pseudoarthrosis, subsidence, and migration of the cages. Limited evidence on the clinical outcome of PEEK cages is found in the literature other than noncomparative cohort studies with only a few randomized controlled trials.

PURPOSE

To assess the clinical and radiographic outcome of PEEK cages in the treatment of degenerative disc disorders and/or spondylolisthesis in the cervical spine.

STUDY DESIGN

Systematic review of all randomized controlled trials and prospective and retrospective nonrandomized comparative studies with a minimum follow-up of 6 months and all noncomparative cohort studies with a long-term follow-up of more than 5 years.

OUTCOME MEASURES

The primary outcome variable was clinical performance. Secondary outcome variables consisted of radiographic scores.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched according to the Preferred Reporting Items of Systematic reviews and Meta-Analyses statement and Meta-analysis Of Observational Studies in Epidemiology guidelines. No conflict of interest reported. No funding received.

RESULTS

A total of 223 studies were identified, of which 10 studies were included. These comprised two randomized controlled trials, five prospective comparative trials, and three retrospective comparative trials.

CONCLUSIONS

Minimal evidence for better clinical and radiographic outcome is found for PEEK cages compared with bone grafts in the cervical spine. No differences were found between PEEK, titanium, and carbon fiber cages. Future studies are needed to improve methodology to minimize bias. Publication of lumbar interbody fusion studies needs to be promoted because differences in clinical and/or radiographic scores are more likely to be demonstrated in this part of the spine.

Retrospective study on effectiveness of activ L total disc replacement: clinical and radiographical results of 1- to 3-year follow-up

STUDY DESIGN

Retrospective case series study.

OBJECTIVE

To assess the effectiveness of activ L total disc replacement (TDR) on degenerative disc diseases with the clinical and radiographical results.

SUMMARY OF BACKGROUND DATA

There are few reports on activ L TDR. This is the first one from China.

METHODS

From March 2009 to March 2012, 32 patients with degenerative disc diseases underwent mono- or bisegmental lumbar TDR. Mean age was 45.1 years (32-58 yr). Clinical outcomes were measured by Oswestry Disability Index and Visual analogue scale pre- and postoperatively (1, 2, and 3 yr). Radiographical parameters as range of motion and intervertebral disc height of the index- and adjacent segments were also measured. Prosthesis subsidence and heterotopic ossification were observed during the follow-up period. Work status was also tracked.

RESULTS

Thirty patients were available for a mean follow-up of 28.8 months and had complete radiographical data. At the final follow-up, the success rate was 86.7%. Visual analogue scale score for low back pain and leg pain, and Oswestry Disability Index scores significantly improved after surgery. Average intervertebral disc heights of patients with more than 3 years' follow-up at the index segment and upper and lower adjacent segments were 12.87 mm, 12.61 mm, and 11.62 mm, respectively, showing no significant difference compared with preoperative scores. The range of motion of the index and upper adjacent segments showed a significant increase for patients with more than 3 years' follow-up. Changes of range of motion at lower adjacent segment were not significant. We observed tears of the iliac vein in 2 patients, prosthesis subsidence in 3 patients, and heterotopic ossification in 1 patient. At the final follow-up, 18 patients went back to their original work, 8 patients changed jobs, and 4 patients stopped working.

CONCLUSION

The 1- to 3-year follow-up of this cohort of patients showed satisfactory clinical outcomes. The long-term results of activ L TDR need more investigation.

LEVEL OF EVIDENCE

2.

Surgical treatment of the osteoporotic spine with bone cement-injectable cannulated pedicle screw fixation: technical description and preliminary application in 43 patients

OBJECTIVES

To describe a new approach for the application of polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws.

METHODS

Between June 2010 and February 2013, 43 patients with degenerative spinal disease and osteoporosis (T-score <-2.5) underwent lumbar fusion using cement-injectable cannulated pedicle screws. Clinical outcomes were evaluated using a Visual Analog Scale and the Oswestry Disability Index. Patients were given radiographic follow-up examinations after 3, 6, and 12 months and once per year thereafter.

RESULTS

All patients were followed for a mean of 15.7 ± 5.6 months (range, 6 to 35 months). The Visual Analog Scale and Oswestry Disability Index scores showed a significant reduction in back pain (p = 0.018) and an improvement in lower extremity function (p = 0.025) in patients who underwent lumbar fusion using the novel screw. Intraoperative cement leakage occurred in four patients, but no neurological complications were observed. Radiological observation indicated no loosening or pulling out of the novel screw, and bone fusion was excellent.

CONCLUSIONS

The described polymethylmethacrylate augmentation technique using bone cement-injectable cannulated pedicle screws can reduce pain and improve spinal dysfunction in osteoporotic patients undergoing osteoporotic spine surgery.