Efficacy of Biphasic Calcium Phosphate Ceramic With a Needle-shaped Surface Topography Versus Autograft in Instrumented Posterolateral Spinal Fusion: A Randomized Trial.

STUDY DESIGN: A multicenter randomized controlled noninferiority trial with intrapatient comparisons. OBJECTIVE: The aim of this study was to determine noninferiority of a slowly resorbable Biphasic Calcium Phosphate with submicron microporosity (BCP<µm, MagnetOs™ Granules) as an alternative for autograft in instrumented posterolateral fusion (PLF). SUMMARY OF BACKGROUND DATA: Successful spinal fusion with a solid bone bridge between the vertebrae is traditionally achieved by grafting with autologous iliac bone. However, the disadvantages of autograft and unsatisfactory fusion rates have prompted the exploration of alternatives, including ceramics. Nevertheless, clinical evidence for the standalone use of these materials is limited. METHODS: Adults indicated for instrumented PLF (one to six levels) were enrolled at five participating centers. After bilateral instrumentation and fusion-bed preparation, the randomized allocation side (left or right) was disclosed. Per segment 10cc of BCP<µm granules (1-2 mm) was placed in the posterolateral gutter on one side and 10cc autograft on the contralateral side. Fusion was systematically scored on 1-year follow-up CT scans. The study was powered to detect >15% inferiority with binomial paired comparisons of the fusion performance score per treatment side. RESULTS: Of the 100 patients (57 ± 12.9 years, 62% female), 91 subjects and 128 segments were analyzed. The overall posterolateral fusion rate per segment (left and/or right) was 83%. For the BCP<µm side only the fusion rate was 79% vs. 47% for the autograft side (difference 32 percentage points, 95% CI = 23-41). Analysis of the primary outcome confirmed the noninferiority of BCP<µm with an absolute difference in paired proportions of 39.6% (95% CI = 26.8-51.2, < 0.001). CONCLUSION: This clinical trial demonstrates noninferiority and even indicates superiority of MagnetOs™ Granules as a standalone ceramic compared to autograft for posterolateral spinal fusion. These results challenge the belief that autologous bone is the most optimal graft material.

Increasing Fusion Rate Between 1 and 2 Years After Instrumented Posterolateral Spinal Fusion and the Role of Bone Grafting.

STUDY DESIGN: Two-year clinical and radiographic follow-up of a double-blind, multicenter, randomized, intra-patient controlled, non-inferiority trial comparing a bone graft substitute (AttraX Putty) with autograft in instrumented posterolateral fusion (PLF) surgery. OBJECTIVES: The aim of this study was to compare PLF rates between 1 and 2 years of follow-up and between graft types, and to explore the role of bone grafting based on the location of the PLF mass. SUMMARY OF BACKGROUND DATA: There are indications that bony fusion proceeds over time, but it is unknown to what extent this can be related to bone grafting. METHODS: A total of 100 adult patients underwent a primary, single- or multilevel, thoracolumbar PLF. After instrumentation and preparation for grafting, the randomized allocation side of AttraX Putty was disclosed. The contralateral posterolateral gutters were grafted with autograft. At 1-year follow-up, and in case of no fusion at 2 years, the fusion status of both sides of each segment was blindly assessed on CT scans. Intertransverse and facet fusion were scored separately. Difference in fusion rates after 1 and 2 years and between grafts were analyzed with a Generalized Estimating Equations (GEE) model (P < 0.05). RESULTS: The 2-year PLF rate (66 patients) was 70% at the AttraX Putty and 68% at the autograft side, compared to 55% and 52% after 1 year (87 patients). GEE analysis demonstrated a significant increase for both conditions (odds ratio 2.0, 95% confidence interval 1.5-2.7, P < 0.001), but no difference between the grafts (P = 0.595). Ongoing bone formation was only observed between the facet joints. CONCLUSION: This intra-patient controlled trial demonstrated a significant increase in PLF rate between 1 and 2 years after instrumented thoracolumbar fusion, but no difference between AttraX Putty and autograft. Based on the location of the PLF mass, this increase is most likely the result of immobilization instead of grafting. LEVEL OF EVIDENCE: 1.

Development and validation of a prediction tool for pain reduction in adult patients undergoing elective lumbar spinal fusion: a multicentre cohort study.

PURPOSE: On average, 56% of patients report a clinically relevant reduction in pain after lumbar spinal fusion (LSF). Preoperatively identifying which patient will benefit from LSF is paramount to improve clinical decision making, expectation management and treatment selection. Therefore, this multicentre study aimed to develop and validate a clinical prediction tool for a clinically relevant reduction in pain 1 to 2 years after elective LSF. METHODS: The outcomes were defined as a clinically relevant reduction in predominant (worst reported pain in back or legs) pain 1 to 2 years after LSF. Patient-reported outcome measures and patient characteristics from 202 patients were used to develop a prediction model by logistic regression. Data from 251 patients were used to validate the model. RESULTS: Nonsmokers (odds ratio = 0.41 [95% confidence interval = 0.19-0.87]), with lower Body Mass Index (0.93 [0.85-1.01]), shorter pain duration (0.49 [0.20-1.19]), lower American Society of Anaesthesiologists score (4.82 [1.35-17.25]), higher Visual Analogue Scale score for predominant pain (1.05 [1.02-1.08]), lower Oswestry Disability Index (0.96 [0.93-1.00]) and higher RAND-36 mental component score (1.03 [0.10-1.06]) preoperatively had a higher chance of a clinically relevant reduction in predominant pain. The area under the curve of the externally validated model yielded 0.68. A nomogram was developed to aid clinical decision making. CONCLUSIONS: Using the developed nomogram surgeons can estimate the probability of achieving a clinically relevant pain reduction 1 to 2 years after LSF and consequently inform patients on expected outcomes when considering treatment.

Efficacy of a Standalone Microporous Ceramic Versus Autograft in Instrumented Posterolateral Spinal Fusion: A Multicenter, Randomized, Intrapatient Controlled, Noninferiority Trial.

STUDY DESIGN: in the rest of the article written as patient- and observer-blinded, multicenter, randomized, intrapatient controlled, noninferiority trial. OBJECTIVE: The aim of this study was to determine noninferiority of a biphasic calcium-phosphate (AttraX® Putty) as a bone graft substitute for autograft in instrumented posterolateral fusion (PLF). SUMMARY OF BACKGROUND DATA: Spinal fusion with autologous bone graft is a frequently performed surgical treatment. Several drawbacks of autografting have driven the development of numerous alternatives including synthetic ceramics. However, clinical evidence for the standalone use of these materials is limited. METHODS: This study included 100 nontraumatic adults who underwent a primary, single- or multilevel, thoracolumbar, instrumented PLF. After instrumentation and preparation for grafting, the randomized allocation side of AttraX® Putty was disclosed. Autograft was applied to the contralateral side of the fusion trajectory, so each patient served as his/her own control. For the primary efficacy outcome, PLF was assessed at 1-year follow-up on computed tomography scans. Each segment and side was scored as fused, doubtful fusion, or nonunion. After correction for multilevel fusions, resulting in a single score per side, the fusion performance of AttraX Putty was tested with a noninferiority margin of 15% using a 90% confidence interval (CI). RESULTS: There were 49 males and 51 females with a mean age of 55.4 ±â€Š12.0 (range 27-79) years. Two-third of the patients underwent a single-level fusion and 62% an additional interbody fusion procedure. The primary analysis was based on 87 patients, including 146 instrumented segments. The fusion rate of AttraX Putty was 55% versus 52% at the autograft side, with an overall fusion rate of 71%. The 90% CI around the difference in fusion performance excluded the noninferiority margin (difference = 2.3%, 90% CI = -9.1% to +13.7%). CONCLUSION: The results of this noninferiority trial support the use of AttraX Putty as a standalone bone graft substitute for autograft in instrumented thoracolumbar PLF. LEVEL OF EVIDENCE: 1.

Patients Cannot Reliably Distinguish the Iliac Crest Bone Graft Donor Site From the Contralateral Side After Lumbar Spine Fusion: A Patient-blinded Randomized Controlled Trial.

STUDY DESIGN: A multicenter, randomized, intrapatient controlled trial. OBJECTIVE: This study investigated whether lumbar fusion patients blinded to the harvest site (A) can identify the iliac crest used for bone harvesting and (B) whether this iliac crest is more painful than the contralateral side. SUMMARY OF BACKGROUND DATA: Spinal fusion with iliac crest autograft is a frequently performed surgical procedure. A widely reported disadvantage of the harvesting procedure is potential donor site morbidity. This has driven the development of many bone graft substitutes. However, more recently the incidence and severity of donor site pain is debated, especially in lumbar fusion surgery. METHODS: Ninety-two nontraumatic adult patients underwent a posterolateral (thoraco)lumbar fusion. Iliac crest bone graft was harvested unilaterally through the primary midline incision. At 6 weeks, 3 months, 6 months, and 1 year follow-up, patients were asked to identify the donor site and to rate pain in their back, left iliac crest and right iliac crest on a Visual Analogue Scale (VAS). RESULTS: Ninety patients, 44 males and 46 females with a mean age of 54 years, were analyzed. The left/right distribution of the iliac crest donor site was 50/50 and 89% of the patients underwent a lumbar fusion below L3. Only 24% patients identified the harvest site correctly. Moreover, the VAS pain scores for the donor site and contralateral iliac crest did not differ and were at each timepoint lower than the scores for back pain. CONCLUSION: This study showed that, during the first year after lumbar fusion surgery via a single midline incision approach, patients could not reliably identify the iliac crest used for bone graft harvesting and this iliac crest was not more painful than the untouched contralateral iliac crest. Therefore, donor site pain should not be the main reason to use bone graft alternatives for lumbar spinal fusion. LEVEL OF EVIDENCE: 2.

Movement Along the Spine Induced by Transcranial Electrical Stimulation Related Electrode Positioning.

STUDY DESIGN: A prospective, nonrandomized cohort study. OBJECTIVE: To describe a technique quantifying movement induced by transcranial electrical stimulation (TES) induced movement in relation to the positioning of electrodes during spinal deformity surgery. SUMMARY OF BACKGROUND DATA: TES induced movement may cause injuries and delay surgical procedures. When TES movements are evoked, muscles other than those being monitored any adjustments in stimulation protocols and electrode positioning may be expected to minimize movement whereas preserving quality of monitoring. In this study, seismic evoked responses (SER) induced through TES were studied at different electrode positions. METHODS: Intraoperative TES-motor evoked potentials were carried out in 12 patients undergoing corrective spine surgery. Accelerometer transducers recorded SER in two directions at four different locations of the spine for TES-electrode montage groups Cz-Fz and C3-C4. A paired t test was used to compare the means of SER and the relationship between movement and TES electrode positioning. RESULTS: SERs were strongest in the upper body. All mean SERs values for the Cz-Fz group were up to five times larger when compared with the C3-C4 group. However, there were no differences between the C3-C4 and Cz-Fz groups in the lower body locations. Both electrode montage groups showed a gradual stepwise reduction in all mean SER values along the spine from the cranial to caudal region. For the upper body locations, there were no significant associations between SER and both montages; in contrast, a significant association SER was demonstrated in the lumbar region. CONCLUSION: At supramaximum levels, movements resulting from multipulse TES are likely caused by relatively strong contractions from muscles in the neck resulting from direct extracranial stimulation. When interchanging electrode montages in individual cases, the movement in the neck may become reduced. At lumbar levels transcranial evoked muscle contractions dominate movement in the surgically exposed areas. LEVEL OF EVIDENCE: 4.