Adjunctive Use of Bone Growth Stimulation Increases Cervical Spine Fusion Rates in Patients at Risk for Pseudarthrosis.

STUDY DESIGN: A prospective multicenter clinical trial (NCT03177473) was conducted with a retrospective cohort used as a control arm. OBJECTIVE: The purpose of this study was to evaluate cervical spine fusion rates in subjects with risk factors for pseudarthrosis who received pulsed electromagnetic field (PEMF) treatment. SUMMARY OF BACKGROUND DATA: Certain risk factors predispose patients to pseudarthrosis, which is associated with prolonged pain, reduced function, and decreased quality of life. METHODS: Subjects in the PEMF group were treated with PEMF for 6 months postoperatively. The primary outcome measure was fusion status at the 12-month follow-up period. Fusion status was determined using anterior/posterior, lateral, and flexion/extension radiographs and computed tomography (without contrast). RESULTS: A total of 213 patients were evaluated (PEMF, n=160; Control, n=53). At baseline, the PEMF group had a higher percentage of subjects who used nicotine ( P =0.01), had osteoporosis ( P <0.05), multi-level disease ( P <0.0001), and were >65 years of age ( P =0.01). The PEMF group showed over two-fold higher percentage of subjects that had ≥3 risk factors (n=92/160, 57.5%) compared with the control group (n=14/53, 26.4%). At the 12-month follow-up, the PEMF group demonstrated significantly higher fusion rates compared with the control (90.0% vs. 60.4%, P <0.05). A statistically significant improvement in fusion rate was observed in PEMF subjects with multi-level surgery ( P <0.0001) and high BMI (>30 kg/m 2 ; P =0.0021) when compared with the control group. No significant safety concerns were observed. CONCLUSIONS: Adjunctive use of PEMF stimulation provides significant improvements in cervical spine fusion rates in subjects having risk factors for pseudarthrosis. When compared with control subjects that did not use PEMF stimulation, treated subjects showed improved fusion outcomes despite being older, having more risk factors for pseudarthrosis, and undergoing more complex surgeries.

Randomized Trial of Augmented Pelvic Fixation in Patients Undergoing Thoracolumbar Fusion for Adult Spine Deformity: Initial Results from a Multicenter Randomized Trial.

BACKGROUND: The optimal configuration for spinopelvic fixation during multilevel spine fusion surgery for adult spine deformity remains unclear. Postoperative sacroiliac (SI) joint pain, S2AI screw loosening and implant breakage could be related to continued motion of the SI joint with use of only a single point of fixation across the SI joint. METHODS: Prospective, international, multicenter randomized controlled trial of 222 patients with adult spine deformity scheduled for multilevel (4 or more levels) spine fusion surgery with pelvic fixation. Subjects were randomized to sacroalar (S2) iliac (S2AI) screws alone for pelvic fixation or S2AI + triangular titanium implants placed cephalad to S2AI screws. Quad rod techniques were not allowed or used. Baseline spinal deformity measures were read by an independent radiologist. Site-reported perioperative adverse events were reviewed by a clinical events committee. Quality of life questionnaires and other clinical outcomes are in process with planned 2-year follow-up. RESULTS: One hundred thirteen participants were assigned to S2AI and 109 to S2AI + titanium triangular implants (TTI). 35/222 (16%) of all subjects had a history of SI joint pain or were diagnosed with SI joint pain during preoperative workup. Three-month follow-up was available in all but 4 subjects. TTI placement was successful in 106 of 109 (98%) subjects assigned to TTI. In 2 cases, TTI could not be placed due to anatomical considerations. Three TTI ventral iliac breaches were observed, all of which were managed non-surgically. One TTI subject had a transverse sacral fracture and 1 TTI subject had malposition of the implant requiring removal. CONCLUSIONS: SI joint pain is common in patients with adult spinal deformity who are candidates for multilevel spine fusion surgery. Concurrent placement of TTI parallel to S2AI screws during multilevel spine fusion surgery is feasible and safe. Further follow-up will help to determine the clinical value of this approach to augment pelvic fixation.

Static Magnetic Fields within Spinal Interbody Cages for the Promotion of Spinal Arthrodesis: A Pilot Study.

BACKGROUND: Spinal arthrodesis is a commonly performed spinal operation. Spinal arthrodesis can be complicated by pseudoarthrosis and resultant hardware failure. Static magnetic fields (SMF) have the ability to improve bone fusion. We seek to assess the feasibility of the construction and implantation of a lumbar interbody cage equipped with a SMF in a caprine model. METHODS: Six skeletally mature female Boer goats underwent a lateral approach for placement of an interbody graft at lumbar (L) 1-2 and 3-4. The goats were divided into 2 groups of 3 animals. The interbody graft contained a neodymium iron boron magnet in the experimental group and a nonmagnetic titanium sham in the control group. Both groups contained a synthetic bone graft. Blinded radiographic and histologic evaluation was performed at predetermined timepoints to assess degree of bony fusion and osseointegration. RESULTS: All 6 goats underwent successful placement of lumbar interbody grafts. At the 1-month postoperative computed tomography, 1 goat in the experimental group and 1 goat in the control group were noted to have dislodged their intervertebral cage. Qualitative radiographic and histologic evaluation identified enhanced bone formation, bone density, and osteointegration of the graft in the experimental group. CONCLUSIONS: A spinal interbody cage containing a neodymium iron boron magnet for the production of a local SMF is feasible. Preliminary data suggests enhanced bone formation, bone density, and osseointegration of the graft.

Thoracic range of motion, stability, and correlation to imaging-determined degeneration.

OBJECT The degenerative process of the spinal column results in instability followed by a progressive loss of segmental motion. Segmental degeneration is associated with intervertebral disc and facet changes, which can be quantified. Correlating this degeneration with clinical segmental motion has not been investigated in the thoracic spine. The authors sought to determine if imaging-determined degeneration would correlate with native range of motion (ROM) or the change in ROM after decompressive procedures, potentially guiding clinical decision making in the setting of spine trauma or following decompressive procedures in the thoracic spine. METHODS Multidirectional flexibility tests with image analysis were performed on thoracic cadaveric spines with intact ib cage. Specimens consisted of 19 fresh frozen human cadaveric spines, spanning C-7 to L-1. ROM was obtained for each specimen in axial rotation (AR), flexion-extension (FE), and lateral bending (LB) in the intact state and following laminectomy, unilateral facetectomy, and unilateral costotransversectomy performed at either T4-5 (in 9 specimens) or T8-9 (in 10 specimens). Image grading of segmental degeneration was performed utilizing 3D CT reconstructions. Imaging scores were obtained for disc space degeneration, which quantified osteophytes, narrowing, and endplate sclerosis, all contributing to the Lane disc summary score. Facet degeneration was quantified using the Weishaupt facet summary score, which included the scoring of facet osteophytes, narrowing, hypertrophy, subchondral erosions, and cysts. RESULTS The native ROM of specimens from T-1 to T-12 (n = 19) negatively correlated with age in AR (Pearson's r coefficient = -0.42, p = 0.070) and FE (r = -0.42, p = 0.076). When regional ROM (across 4 adjacent segments) was considered, the presence of disc osteophytes negatively correlated with FE (r = -0.69, p = 0.012), LB (r = -0.82, p = 0.001), and disc narrowing trended toward significance in AR (r = -0.49, p = 0.107). Facet characteristics, scored using multiple variables, showed minimal correlation to native ROM (r range from -0.45 to +0.19); however, facet degeneration scores at the surgical level revealed strong negative correlations with regional thoracic stability following decompressive procedures in AR and LB (Weishaupt facet summary score: r = -0.52 and r = -0.71; p = 0.084 and p = 0.010, respectively). Disc degeneration was not correlated (Lane disc summary score: r = -0.06, p = 0.861). CONCLUSIONS Advanced age was the most important determinant of decreasing native thoracic ROM, whereas imaging characteristics (T1-12) did not correlate with the native ROM of thoracic specimens with intact rib cages. Advanced facet degeneration at the surgical level did correlate to specimen stability following decompressive procedures, and is likely indicative of the terminal stages of segmental degeneration.

Effects of an immunomodulatory therapy and chondroitinase after spinal cord hemisection injury.

BACKGROUND: Individually, immunomodulatory therapy and chondroitinases have demonstrated neuroprotective and potential neuroregenerative effects following spinal cord injury. OBJECTIVE: To investigate the therapeutic potential of combined immunomodulatory and chondroitin sulfate-glycosaminoglycan degradation therapy in spinal cord injury. METHODS: A combined immunomodulatory treatment using (1) liposome-encapsulated clodronate (selectively depletes peripheral macrophages), and (2) rolipram (a selective type 4 phosphodiesterase inhibitor), along with the chondroitin sulfate proteoglycan-glycosaminoglycan-degrading enzyme, chondroitinase ABC (ChABC), was assessed for its potential to promote axonal regrowth and improve locomotor recovery following midthoracic spinal cord hemisection injury in adult rats. RESULTS: We demonstrate that combined treatment with liposomal clodronate, rolipram, and ChABC attenuates macrophage accumulation at the site of injury, reduces axonal die-back of injured dorsal column axons, and produces the greatest improvement in locomotor recovery at 6 weeks postinjury compared with controls and noncombined therapy. Anterograde and retrograde tracing revealed that delivery of clodronate, rolipram, and ChABC did not promote substantial axonal regeneration through the site of injury, although the treatment did limit the extent of axonal die-back. Histological assessments revealed that combined treatment with clodronate/rolipram and/or ChABC resulted in a significant reduction in lesion size and cystic cavitation in comparison with injured controls. Combined clodronate, rolipram, and ChABC treatment reduced the accumulation of macrophages within the injured spinal cord 7 weeks after injury. CONCLUSION: The present data suggest that delivery of an immunomodulatory therapy consisting of clodronate and rolipram, in combination with ChABC, reduces axonal injury and enhances neuroprotection, plasticity, and hindlimb functional recovery after hemisection spinal cord injury in adult rats.