Six-Year Follow-up of a Randomized Controlled Trial of i-FACTOR Peptide-Enhanced Bone Graft Versus Local Autograft in Single-Level Anterior Cervical Discectomy and Fusion

BACKGROUND

Previous analyses of the US Food and Drug Administration (FDA) Investigational Device Exemption study demonstrated the superiority of i-FACTOR compared with local autograft bone in single-level anterior cervical discectomy and fusion (ACDF) at 12 and 24 months postoperatively in a composite end point of overall success.

OBJECTIVE

To report the final, 6-year clinical and radiological outcomes of the FDA postapproval study.

METHODS

Of the original 319 subjects enrolled in the Investigational Device Exemption study, 220 participated in the postapproval study (106 i-FACTOR and 114 control).

RESULTS

The study met statistical noninferiority success for all 4 coprimary end points. Radiographic fusion was achieved in 99% (103/104) and 98.2% (109/111) in i-FACTOR and local autograft subjects, mean Neck Disability Index improvement from baseline was 28.6 (24.8, 32.3) in the i-FACTOR and 29.2 (25.6, 32.9) in the control group, respectively (noninferiority P < .0001). The neurological success rate at 6 years was 95.9% (70/73) in i-FACTOR subjects and 93.7% (70/75) in local autograft subjects (noninferiority P < .0001). Safety outcomes were similar between the 2 groups. Secondary surgery on the same or different cervical levels occurred in 20/106 (18.9%) i-FACTOR subjects and 23/114 (20.2%) local autograft subjects ( P = .866). Secondary outcomes (pain, SF-36 physical component score and mental component score) in i-FACTOR subjects were similar to those in local autograft subjects.

CONCLUSION

i-FACTOR met all 4 FDA-mandated noninferiority success criteria and demonstrated safety and efficacy in single-level anterior cervical discectomy and fusion for cervical radiculopathy through 6 years postoperatively. Safety outcomes are acceptable, and the clinical and functional outcomes observed at 12 and 24 months remained at 72 months.

Two-Year Clinical and Radiological Outcomes in Patients With Diabetes Undergoing Single-Level Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Secondary analysis of data from the multicenter, randomized, parallel-controlled Food and Drug Administration (FDA) investigational device exemption study.

OBJECTIVE

Studies on outcomes following anterior cervical discectomy and fusion (ACDF) in individuals with diabetes are scarce. We compared 24-month radiological and clinical outcomes in individuals with and without diabetes undergoing single-level ACDF with either i-FACTOR or local autologous bone.

METHODS

Between 2006 and 2013, 319 individuals with single-level degenerative disc disease (DDD) and no previous fusion at the index level underwent ACDF. The presence of diabetes determined the 2 cohorts. Data collected included radiological fusion evaluation, neurological outcomes, Neck Disability Index (NDI), Visual Analog Scale (VAS) scores, and the 36-Item Short Form Survey Version 2 (SF-36v2) Physical and Mental component summary scores.

RESULTS

There were 35 individuals with diabetes (11.1%; average body mass index [BMI] = 32.99 kg/m²; SD = 5.72) and 284 without (average BMI = 28.32 kg/m²; SD = 5.67). The number of nondiabetic smokers was significantly higher than diabetic smokers: 73 (25.70%) and 3 (8.57%), respectively. Preoperative scores of NDI, VAS arm pain, and SF-36v2 were similar between the diabetic and nondiabetic participants at baseline; however, VAS neck pain differed significantly between the cohorts at baseline (P = .0089). Maximum improvement for NDI, VAS neck and arm pain, and SF-36v2 PCS and MCS scores was seen at 6 months in both cohorts and remained stable until 24 months.

CONCLUSIONS

ACDF is effective for cervical radiculopathy in patients with diabetes. Diabetes is not a contraindication for patients requiring single-level surgery for cervical DDD.

Pedicle violation and Navigational errors in pedicle screw insertion using the intraoperative O-arm: A preliminary report

Background

Use of computer-assisted insertion of pedicle screws has some advantages owing to the reportedly decreased incidence of pedicle breach and clinical events. Registration-based methods based on preoperative computed tomography imaging, 2D fluoroscopy, and 3D fluoroscopy are the most popular, however each has its limitations. O-arm–based navigation, which uses intraoperative acquisition and registration of navigated images, may overcome many of these disadvantages. We set out to study the clinical accuracy and navigational accuracy for pedicle screw insertion using our recently acquired O-arm and present our preliminary findings.

Methods

The first 26 patients operated consecutively for L4-5 fusion were included in the study. O-arm–based navigation was used to insert the pedicle screws. Postoperative computed tomography images were acquired and assessed for pedicle breach and anterior cortical perforation. Planned trajectories of each screw were compared with the actual trajectories in the postoperative images to assess navigational accuracy in both axial and sagittal planes.

Results

A total of 104 screws were inserted. One screw (1%) breached the pedicle laterally. Nonsignificant anterolateral cortical perforations were noted in 7 screws (6.7%), all of which occurred at L5 level. The mean axial and sagittal navigational error was 2.3° (±1.7) and 3.1° (±2.3), respectively. There were no significant differences in the errors between L4 or L5 level. The occurrence of anterior perforation correlated with the degree of axial (P = .02) but not sagittal (P = .12) navigational error. There were no clinical events related to the screw insertion.

Conclusion

Use of O-arm–guided pedicle screw insertion was associated with low incidence of pedicle breach (1%) and a low range of navigational error in both sagittal and axial planes. Anterolateral vertebral body perforation was higher at L5 without any negative clinical events. Despite the high need for technical support, we found that O-arm was a very efficient tool for accurate pedicle screw insertion.

Multi-site study of surgical practice in neurosurgery based on surgical process models

Surgical Process Modelling (SPM) was introduced to improve understanding the different parameters that influence the performance of a Surgical Process (SP). Data acquired from SPM methodology is enormous and complex. Several analysis methods based on comparison or classification of Surgical Process Models (SPMs) have previously been proposed. Such methods compare a set of SPMs to highlight specific parameters explaining differences between populations of patients, surgeons or systems. In this study, procedures performed at three different international University hospitals were compared using SPM methodology based on a similarity metric focusing on the sequence of activities occurring during surgery. The proposed approach is based on Dynamic Time Warping (DTW) algorithm combined with a clustering algorithm. SPMs of 41 Anterior Cervical Discectomy (ACD) surgeries were acquired at three Neurosurgical departments; in France, Germany, and Canada. The proposed approach distinguished the different surgical behaviors according to the location where surgery was performed as well as between the categorized surgical experience of individual surgeons. We also propose the use of Multidimensional Scaling to induce a new space of representation of the sequences of activities. The approach was compared to a time-based approach (e.g. duration of surgeries) and has been shown to be more precise. We also discuss the integration of other criteria in order to better understand what influences the way the surgeries are performed. This first multi-site study represents an important step towards the creation of robust analysis tools for processing SPMs. It opens new perspectives for the assessment of surgical approaches, tools or systems as well as objective assessment and comparison of surgeon's expertise.

The role of magnetic resonance imaging in the management of acute spinal cord injury

Magnetic resonance imaging (MRI) has become the gold standard for imaging neurological tissues including the spinal cord. The use of MRI for imaging in the acute management of patients with spinal cord injury has increased significantly. This paper used a vigorous literature review with Downs and Black scoring, followed by a Delphi vote on the main conclusions. MRI is strongly recommended for the prognostication of acute spinal cord injury. The sagittal T2 sequence was particularly found to be of value. Four prognostication patterns were found to be predictive of neurological outcome (normal, single-level edema, multi-level edema, and mixed hemorrhage and edema). It is recommended that MRI be used to direct clinical decision making. MRI has a role in clearance, the ruling out of injury, of the cervical spine in the obtunded patient only if there is abnormality of the neurological exam. Patients with cervical spinal cord injuries have an increased risk of vertebral artery injuries but the literature does not allow for recommendation of magnetic resonance angiography as part of the routine protocol. Finally, time repetition (TR) and time echo (TE) values used to evaluate patients with acute spinal cord injury vary significantly. All publications with MRI should specify the TR and TE values used.

Dietary starch type affects body weight and glycemic control in freely fed but not energy-restricted obese rats

This study comprised 2 experiments that tested the hypothesis that a high-amylose starch diet (AMO) would improve body weight and glycemic control relative to a high-amylopectin starch diet (AMN) in rats with diet-induced obesity. After inducing obesity with a high-fat and -energy diet (Expt. 1), male Sprague-Dawley rats (n = 46) were divided into 4 groups and given free or restricted access to either an AMN or an AMO diet for 4 wk (Expt. 2). After 3 wk, rats from each group underwent an oral glucose tolerance test. At the end of the experiment, food-deprived rats were killed by decapitation and blood and tissues were collected for analyses. AMO led to lower total energy intake, weight gain, fat pad mass, and glycemic response but higher insulin sensitivity index than AMN, only when consumed ad libitum (AL) (P < 0.05). AMO led to higher glucagon-like peptide-1 and peptide YY responses and mRNA levels, independent of feeding paradigm (P < 0.01). The mRNA levels of key neuropeptide systems involved in the regulation of food intake were affected only by energy restriction. On the other hand, AMO resulted in higher expression of uncoupling protein-1 in the brown adipose tissue than AMN in rats that consumed food AL (P < 0.05). The effects of AMO appear to be mediated by its high resistant starch content rather than its glycemic index. We conclude that starches high in AMO can be effective in weight and glycemic control in obesity.

Cellular processing of the nerve growth factor precursor by the mammalian pro-protein convertases

In order to define the enzymes responsible for the maturation of the precursor of nerve growth factor (proNGF), its biosynthesis and intracellular processing by the pro-protein convertases furin, PC1, PC2, PACE4, PC5 and the PC5 isoform PC5/6-B were analysed using the vaccinia virus expression system in cells containing a regulated and/or a constitutive secretory pathway. Results demonstrate that in both cell types furin, and to a lesser extent PACE4 and PC5/6-B, are the best candidate proNGF convertases. Furthermore, two processed NGF forms of 16.5 and 13.5 kDa were evident in constitutively secreting cell lines such as LoVo and BSC40 cells, whereas only the 13.5 kDa form was observed in AtT20 cells, which contain secretory granules. Both forms display the same N-terminal sequence as mature NGF, and were also produced following site-directed mutagenesis of the C-terminal Arg-Arg sequence of NGF into Ala-Ala, suggesting that the difference between them is not at the C-terminus. Co-expression of proNGF with furin and either chromogranin B or secretogranin II (but not chromogranin A) in BSC40 cells eliminated the 16.5 kDa form. Data also show that N-glycosylation of the pro-segment of proNGF and trimming of the oligosaccharide chains are necessary for the exit of this precursor from the endoplasmic reticulum and its eventual processing and secretion. Sulphate labelling experiments demonstrated that proNGF is processed into mature NGF following the arrival of the precursor in the trans-Golgi network. This comparative study shows that the three candidate mammalian subtilisin/kexin-like convertases identified process proNGF into NGF and that the nature of the final processed products is dependent on the intracellular environment.

Pharmacokinetics of sufentanil in normal children

The pharmacokinetic variables of sufentanil were studied in 20 healthy children between two and eight years of age. The plasma concentrations of sufentanil were measured for up to 480 min after administration of a bolus of sufentanil, 1-3 micrograms.kg-1. The distribution half-life (t1/2 alpha) was 5.2 +/- 2.2 (mean +/- SD) min and the elimination half life (t1/2 beta) was 97.0 +/- 42.0 min. The volume of distribution at steady state (Vdss) was 2.9 +/- 0.6 L.kg-1 and the clearance was 30.5 +/- 8.8 ml.kg-1.min-1. The Vdss was one and a half times greater than that reported in adults when expressed as a function of body weight but similar to that of adults when expressed as a function of body surface area. According to our results, the clearance of sufentanil in normal children between two and eight years of age is twice as rapid as that described in adults and adolescents. A greater clearance of sufentanil in children suggests that they would require relatively greater maintenance doses than adults.

Effects of oral cimetidine and ranitidine on gastric pH and residual volume in children

The effect of orally administered cimetidine 7.5 mg/kg (group 1), ranitidine 1.5 mg/kg (group 2), ranitidine 2.0 mg/kg (group 3), or a placebo (group 4) on gastric pH and gastric residual volume of 60 healthy children 2-6 yr of age admitted for elective surgery was evaluated. Both cimetidine and ranitidine administered 1-2 h prior to induction of anesthesia effectively increased the gastric pH:5,47 - 1.85 ml/kg (group 1), 4.92 +/- 2.1 ml/kg (group 2), 5.30 +/- 1.82 ml/kg (group 3) compared with 1.75 +/- 0.58 ml/kg (group 4) (P less than 0.001). A single dose of ranitidine 1.5 mg/kg was an effective as ranitidine 2.0 mg/kg and cimetidine 7.5 mg/kg. Neither drug decreased the gastric residual volume: 0.32 +/- 0.33 ml/kg (group 1), 0.31 +/- 0.06 ml/kg (group 2), 0.23 +/- 0.05 ml/kg (group 3), and 0.33 +/- 0.05 ml/kg (group 4). The combination of a volume greater than 0.4 ml/kg and a pH less than 2.5 was found in 33% (five of 15) of patients in the placebo group (group 4). In contrast, there were no patients with this combination in groups 1, 2, or 3 (P less than 0.001).