Daisuke Umebayashi

Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Disorders: Mini-open TLIF and Corrective TLIF

Minimally invasive transforaminal lumbar interbody fusion (TLIF) as a short fusion is widely accepted among the spine surgeons. However in the long fusion for degenerative kyphoscoliosis, corrective spinal fixation by an open method is thought to be frequently selected. Our objective is to study whether the mini-open TLIF and corrective TLIF contribute to the improvement of the spinal segmental and global alignment. We divided the patients who performed lumbar fixation surgery into three groups. Group 1 (G1) consisted of mini-open TLIF procedures without complication. Group 2 (G2) consisted of corrective TLIF without complication. Group 3 (G3) consisted of corrective TLIF with instrumentation-related complication postoperatively. In all groups, the lumbar lordosis (LL) highly correlated with developing surgical complications. LL significantly changed postoperatively in all groups, but was not corrected in the normal range in G3. There were statistically significant differences in preoperative and postoperative LL and mean difference between the pelvic incidence (PI) and LL between G3 and other groups. The most important thing not to cause the instrumentation-related failure is proper correction of the sagittal balance. In the cases with minimal sagittal imbalance with or without coronal imbalance, short fusion by mini-open TLIF or long fusion by corrective TLIF contributes to good clinical results if the lesion is short or easily correctable. However, if the patients have apparent sagittal imbalance with or without coronal imbalance, we should perform proper correction of the sagittal spinal alignment introducing various technologies.

Posterior Fixation for Atlantoaxial Subluxation in a Case With Complex Anomaly of Persistent First Intersegmental Artery and Assimilation in the C1 Vertebra

We report a very rare case of atlantoaxial subluxation (AAS) with persistent first intersegmental artery (PFIA) and assimilation in the atlas (C1) vertebra. This case demonstrates the difficulty of deciding on a surgical strategy for complex anomalies. A 63-year-old man presented with gait disturbance, neck pain, and severe dysesthesia in his left arm. Past history included a whiplash injury. Dynamic X-ray studies demonstrated an irreducible AAS and assimilation of C1. This subluxation was slightly deteriorated in an extended position. A three-dimensional computed tomography angiography (3DCTA) indicated that the PFIA was located on the left side. We performed a C1 posterior arch resection and C1 lateral mass–axis pedicle screw (C1LM–C2PS) fixation using the modified technique of skewering the occipital condyle and C1 lateral mass. The patient had no postoperative morbidity and his symptoms disappeared immediately after operation. Complex anomalies cause difficulty in determining surgical strategy although several surgical methods for simple craniovertebral junction anomaly have been reported. To avoid significant morbidities associated with vertebral artery injury, surgical strategies for these complex conditions are discussed. The modified technique of a C1 lateral mass screw penetrating the occipital condyle is a viable treatment option.

Balloon Kyphoplasty under Three-dimensional Radiography Guidance

Percutaneous balloon kyphoplasty (PBKP) is generally performed under two-dimensional (2D) radiography guidance (lateral- and anteroposterior (A-P) views) using C-arm fluoroscopy. However, 2D images taken by single-plane or bi-plane fluoroscopy cannot provide information regarding axial views, particularly the Z axis. Lack of information regarding the Z axis prevents the creation of three-dimensional (3D) images. Currently, there has been a progress in interventional X-ray systems, and they are capable of providing 3D radiographic images using a rotational angiography mode which is used to create 3D angiographies. In this report, we described the usefulness of 3D radiography guidance. Patients treated by PBKP was designed to evaluate the efficacy of 3D radiography guidance. These patients experienced osteoporotic vertebral fractures with severe pain. We retrospectively analyzed patients who underwent PBKP from February to December 2016. All patients had a single-level vertebral fracture and underwent surgery by 2D or 3D radiography guidance. We performed 16 patients in 3D radiography guidance, and 10 patients in traditional 2D radiography guidance. This 3D radiography guided PBKP increase the amount of the polymethyl methacrylate (PMMA) injection compared with ordinary 2D method. As a result, postoperative vertebral height and alignment were significantly improved. Both groups have no complication. To confirm the final results and make PBKP more effective, 3D radiography guidance is feasible and safe for balloon kyphoplasty.

O-arm Imaging and Naviation Systems for Transvertebral Anterior Cervical Foraminotomy

Introduction Anterior cervical discectomy and fusion (ACDF) results in excellent initial clinical results for herniated cervical disc and an osteophyte. On the other hand, the development of adjacent segment disease after ACDF is well recognized. However, most patients do not require total discectomy and vertebral fusion because most radiculopathies are caused by focal lesions of the intervertebral foramen. Especially, in patients who have unilateral radiculopathy with physiological alignment, we should avoid removal of healthy discs. Transvertebral anterior cervical foraminotomy (TVACF), nonfusion and nondiscectomy technique, can preserve intervertebral disc and reduce adjacent intervertebral degeneration compared with intervertebral fusion. Therefore, we have reported the advantages and usefulness of TVACF. However, TVACF requires skillfulness, especially for the appropriate drilling direction control for the keyhole. Recently, O-arm imaging and navigation systems were progressed. This navigation systems help to make the correct direction of the keyhole. Material and Methods We have performed TVACF under O-arm imaging and naviation systems. The patient was placed in the supine position. A lateral radiograph was used to identify the skin incision level. A 3.5cm transverse skin incision was made at half a level higher than the affected disc level. We approached the anterior surface of the vertebra from the affected side. After then, O-arm imaging and navigation systems were applied. We determined the appropriate keyhole position under the navigation. The lateral and caudal side trajectory of the tunnel was also decided under the navigation. The tunnel was ~6 mm in diameter. Results Under O-arm imaging and navigation systems, we were able to easily determine the appropriate keyhole position and the lateral and caudal side trajectory of the tunnel. Intraoperative findings and postoperative computed tomography imaging showed the accuracy of keyhole position. Conclusion Successful surgery is possible with using O-arm imaging and navigation systems. This navigation facilitate TVACF. As a result, TVACF is able to be more widely used among spinal surgeons in safe.

Biomechanical Analysis of a Pedicle Screw-Rod System with a Novel Cross-Link Configuration

Study Design The strength effects of a pedicle screw-rod system supplemented with a novel cross-link configuration were biomechanically evaluated in porcine spines. Purpose To assess the biomechanical differences between a conventional cross-link pedicle screw-rod system versus a novel cross-link instrumentation, and to determine the effect of the cross-links. Overview of Literature Transverse cross-link systems affect torsional rigidity, but are thought to have little impact on the sagittal motion of spinal constructs. We tested the strength effects in pullout and flexion-compression tests of novel cross-link pedicle screw constructs using porcine thoracic and lumbar vertebrae. Methods Five matched thoracic and lumbar vertebral segments from 15 porcine spines were instrumented with 5.0-mm pedicle screws, which were then connected with 6.0-mm rods after partial corpectomy in the middle vertebral body. The forces required for construct failure in pullout and flexion-compression tests were examined in a randomized manner for three different cross-link configurations: un-cross-link control, conventional cross-link, and cross-link passing through the base of the spinous process. Statistical comparisons of strength data were analyzed using Students t-tests. Results The spinous process group required a significantly greater pullout force for construct failure than the control group (p=0.036). No difference was found between the control and cross-link groups, or the cross-link and spinous process groups in pullout testing. In flexion-compression testing, the spinous processes group required significantly greater forces for construct failure than the control and cross-link groups (p<0.001 and p=0.003, respectively). However, there was no difference between the control and cross-link groups. Conclusions A novel cross-link configuration that features cross-link devices passing through the base of the spinous processes increased the mechanical resistance in pullout and flexion-compression testing compared to un-cross-link constructs. This configuration provided more resistance to middle-column damage under flexion-compression testing than conventional cross-link configuration.

A Morphologically Atypical Case of Atlantoaxial Rotatory Subluxation

A rare case of atlantoaxial rotatory subluxation occurred after pediatric cervical spine surgery performed to remove a dumbbell-shaped meningioma at the level of the C1/C2 vertebrae. This case is classified as a post-surgical atlantoaxial rotatory subluxation, but has a very rare morphology that has not previously been reported. Although there are several reports about post-surgical atlantoaxial rotatory subluxation, an important point of this case is that it might be directly related to the spinal cord surgery in C1/C2 level. On day 6 after surgery, the patient presented with the Cock Robin position, and a computed tomography scan revealed a normal type of atlantoaxial rotatory subluxation. Manual reduction was performed followed by external fixation with a neck collar. About 7 months after the first surgery, the subluxation became severe, irreducible, and assumed an atypical form where the anterior tubercle of C1 migrated to a cranial position, and the posterior tubercle of C1 and the occipital bone leaned in a caudal direction. The pathogenic process suggested deformity of the occipital condyle and bilateral C2 superior facets with atlantooccipital subluxation. A second operation for reduction and fixation was performed, and the subluxation was stabilized by posterior fixation. We encountered an unusual case of a refractory subluxation that was associated with an atypical deformity of the upper spine. The case was successfully managed by posterior fixation.