Changes in Lumbosacral Anatomy and Vertebral Numbering in Patients with Thoracolumbar and/or Lumbosacral Transitional Vertebrae.

The presence of a thoracolumbar transitional vertebra (TLTV) and/or lumbosacral transitional vertebra (LSTV) may cause wrong-site surgery and problems while measuring spinopelvic parameters, including pelvic incidence and lumbar lordosis. The Castellvi classification of LSTV addresses coronal images but not sagittal or axial images. Therefore, it is unclear how LSTV differs from the normal lumbosacral anatomy. We aimed to investigate the lumbosacral anatomy and vertebral numbering in patients with TLTV and/or LSTV. We performed computed tomography (CT) to identify TLTV, to number presacral vertebrae accurately, and to analyze morphological differences in each LSTV type. METHODS: The medical records of 880 patients who underwent spinopelvic fixation between July 2014 and March 2020 were evaluated for TLTV and LSTV. Castellvi LSTVs (above the promontory on the arcuate line of the ilium) and our newly proposed LSTV ("S6 LSTV," with 6 sacral vertebrae and 5 foramina below the promontory) were analyzed. The anatomical location of the lowest thoracic vertebra was defined, and TLTV with dysplastic ribs was identified. Each LSTV type was examined for its morphological features on sagittal and axial CT images. RESULTS: LSTV was observed in 111 (12.6%) of 880 patients. Castellvi type-III LSTV was the most common (42 [37.8%] of 111), followed by S6 LSTV (37 [33.3%] of 111). TLTV was associated with LSTV (87 [78.4%] of 111) and was commonly identified at T13 (59 [67.8%] of 87). On sagittal CT images, the lumbosacral transitional anatomy of Castellvi LSTVs resembled that of normal L5-S1, and the lumbosacral transitional anatomy of S6 LSTV resembled that of normal S1-S2. When comparing the S1 upper segments on axial CT images, most Castellvi LSTVs exhibited S2-like appearances and most S6 LSTVs exhibited L5-like appearances. CONCLUSIONS: Although LSTV possesses L5 and S1 features, Castellvi LSTVs have more L5 elements than S1 elements. The converse is true for S6 LSTV. At least for the Castellvi type-IIIb LSTV, the vertebra below the Castellvi type-IIIb LSTV should be recognized as S1, but clinically it is better to recognize it as S2. Overlooking TLTV may cause problems in vertebral numbering due to coexisting LSTV. CLINICAL RELEVANCE: Three-dimensional CT images are suitable for detecting transitional vertebrae. This study reveals their morphological features on axial CT images and their lumbosacral anatomy on sagittal CT images.

Extra-articular Portion of the Sacroiliac Joint-Between the Sacral and Pelvic Tuberosities: An Anatomical Guide for the S2-Alar-Iliac Screw Trajectory.

STUDY DESIGN: A novel technique for S2-alar-iliac (S2AI) screw placement was analyzed. OBJECTIVES: Accurate confirmation of the S2AI screw trajectory with free-hand techniques is not simple, although some anatomical landmarks have been reported. To overcome the drawback, we aimed to introduce our technique for S2AI screw placement assisted with a guidewire using a new anatomical landmark. METHODS: A total of 104 S2AI screws of 52 patients who underwent S2AI screw placement were investigated. Navigation software was used to simulate S2AI screw placement preoperatively. Screw placement was performed with the nonfluoroscopic free-hand technique. In this technique, a guidewire is inserted into the ilium from the extra-articular portion of the sacroiliac joint just lateral to the ideal screw entry point toward the tip of the greater trochanter and guides the screw trajectory. If the direction of the guidewire is satisfactory, all procedures of screw insertion are performed accordingly. The screw accuracy was assessed with computed tomography. RESULTS: The modal size of the screw was 9.5 mm × 90 mm. The average horizontal angle was 42.0° (SD = 5.1°) on the right and 40.7° (SD = 4.7°) on the left. Of the 104 screws, 4 screws (3.9%) breached dorsally. No screw-related complication was observed. CONCLUSIONS: Because the guidewire can be inserted at an angle according to the individual morphology of the sacroiliac joint, it will be a reliable guide for the screw trajectory. This technique with a guidewire would help improve the accuracy of S2AI screw placement.

Combined teriparatide and denosumab therapy accelerates spinal fusion following posterior lumbar interbody fusion.

INTRODUCTION: Previous studies reported that teriparatide (recombinant human parathyroid hormone) accelerated spinal fusion following posterior lumbar inter-body fusion surgery, and combination therapy using teriparatide and denosumab increased bone marrow density more than teriparatide alone. The purpose of this study is to evaluate the influence of combination therapy with teriparaide and denosumab on spinal fusion after posterior lumbar interbody fusion. MATERIALS AND METHODS: Sixteen osteoporotic patients with lumbar canal stenosis were randomly divided into two treatment groups, a teriparatide group (n=8; 20µg of teriparatide daily alone, administered from a month before surgery to 12 months after surgery) and a combination group (n=8; 20µg of teriparatide administered daily from a month before surgery to 12 months after surgery with 60mg denosumab every 6 months, administered at 2 and 8 months following surgery). All patients underwent posterior lumbar interbody fusion with local bone grafts. At 3, 6, 9, and 12 months following surgery, bone mineral density at the femoral neck was measured, and biochemical markers were obtained for bone turnover for all cases. Clinical findings were quantified using the Japanese Orthopedic Association scores before surgery, and at 6 and 12 months following surgery. Fusion rates were measured using computed tomography images before surgery, and 6 and 12 months following surgery. RESULTS: Alkaline phosphatase in the teriparatide group increased more than in the combination group at 3 months following surgery (p<0.05). Femoral neck BMD increased more in the combination group than in the teriparatide group at 12 months following surgery. The combination group achieved higher fusion rates than the teriparatide group at 6 months following surgery. CONCLUSIONS: Combination therapy with teriparatide and denosumab increased bone mineral density more than teriparatide alone, and accelerated spinal fusion following posterior lumbar interbody fusion.

The surgical outcome of decompression alone versus decompression with limited fusion for degenerative lumbar scoliosis.

OBJECTIVE The aim of this study was to assess the usefulness of radiological parameters for surgical decision-making in patients with degenerative lumbar scoliosis (DLS) by comparing the clinical and radiological results after decompression or decompression and fusion surgery. METHODS The authors prospectively planned surgical treatment for 298 patients with degenerative lumbar disease between September 2005 and March 2013. The surgical method used at their institution to address intervertebral instability is precisely defined based on radiological parameters. Among 64 patients with a Cobb angle ranging from 10° to 25°, 57 patients who underwent follow-up for more than 2 years postoperatively were evaluated. These patients were divided into 2 groups: those in the decompression group underwent decompression alone (n = 25), and those in the fusion group underwent decompression and short segmental fusion (n = 32). Surgical outcomes were reviewed, including preoperative and postoperative Cobb angles, lumbar lordosis based on radiological parameters, and Japanese Orthopaedic Association (JOA) scores. RESULTS The JOA scores of the decompression group and fusion group improved from 5.9 ± 1.6 to 10.0 ± 2.8 and from 7.2 ± 2.0 to 11.3 ± 2.8, respectively, which was not significantly different between the groups. At the final follow-up, the postoperative Cobb angle in the decompression group changed from 14° ± 2.9° to 14.3° ± 6.4° and remained stable, while the Cobb angle in the fusion group decreased from 14.8° ± 4.0° to 10.0° ± 8.5° after surgery. CONCLUSIONS The patients in both groups demonstrated improved JOA scores and preserved Cobb angles after surgery. The improvement in JOA scores and preservation of Cobb angles in both groups show that the evaluation of spinal instability using radiological parameters is appropriate for surgical decision-making.

Evaluation of functional and structural leg length discrepancy in patients with adolescent idiopathic scoliosis using the EOS imaging system: a prospective comparative study.

BACKGROUND: To our knowledge, no studies have reported the exact structural leg length discrepancies (LLDs) in patients with adolescent idiopathic scoliosis (AIS). Therefore, this study aimed to evaluate the differences between functional and structural LLDs and to examine the correlations between LLDs and spinopelvic parameters in patients with AIS using an EOS imaging system, which permits the three-dimensional reconstruction of spinal and lower-limb bony structures. METHODS: Eighty-two consecutive patients with AIS underwent whole-body EOS radiography in a standing position between August 2014 and March 2016. Functional LLD, lumbar Cobb angle, thoracic curve Cobb angle, coronal balance, and pelvic obliquity were measured using two-dimensional EOS radiography. Structural LLDs were measured using three-dimensional EOS-reconstructed images. The comparison between LLDs was assessed using paired t test. Pearson's correlation coefficient (r) was used to determine potential correlations between the LLDs and spinopelvic alignment parameters. RESULTS: Functional LLDs were significantly larger than structural LLDs (5.6 ± 5.0 vs. 0.2 ± 3.6 mm, respectively; p < 0.001). Both functional and structural LLDs were significantly correlated with pelvic obliquity (r = 0.69 and r = 0.51, respectively; p < 0.001 for both). Functional LLD, but not structural LLD, was correlated with lumbar Cobb angle (r = 0.44, p < 0.001; r = 0.17, p = 0.12, respectively). In addition, functional and structural LLDs were not correlated with thoracic Cobb angle (r = 0.09 and r = - 0.05, respectively; p ≥ 0.68 for both). CONCLUSIONS: Although patients with AIS often have functional LLDs, structural LLDs tend to be smaller. The correlation between functional LLDs and the lumbar Cobb angle indicates that functional LLDs compensate for the lumbar curve. Thus, the difference between functional and structural LLDs indicates a compensatory mechanism involving extension and flexion of the lower limbs.

Optimal trajectory and insertion accuracy of sacral alar iliac screws.

OBJECTIVE: The aim of this study was to analyse the optimal trajectories for sacral alar iliac screws (SAISs) in a Japanese patient population and the clinical assessment of insertion accuracies. METHODS: The ideal trajectories of SAISs, starting from 2 mm medial to the apex of the lateral sacral crest on the midline between S1 and S2 dorsal foramina, were measured in 80 consecutive spinal disease patients (40 males and 40 females; average age: 67.4 ± 8.1 years) using three-dimensional computed tomographic image software. Following these anatomic analyses, accuracies of 32 inserted SAISs in consecutive patients, who underwent long spinal posterior fusion, were investigated clinically. RESULTS: Lateral angulations of optimal SAIS trajectories in males (left: 37.9; right: 37.7) were significantly larger than those than in females (left: 32.8; right: 32.4). Caudal SAIS angulations for females (left: 33.4; right: 33.9) were significantly larger than those in males (left: 27.5; right: 28.0). The 32 SAISs (100 mm long and 9 mm in diameter) assessed clinically were accurately inserted on optimal trajectories. CONCLUSION: The optimal trajectories of SAISs in a Japanese patient population are more lateral in males and more caudal in females. This study examines the clinical safety and accuracy of SAIS insertion on these optimal trajectories.

Validation study of arm positions for evaluation of global spinal balance in EOS imaging.

BACKGROUND: The sagittal vertical axis (SVA) is important in the evaluation of spinal sagittal balance. Although the "fists-on-clavicles" (FOC) position has been widely used in radiographic examinations, it does not define shoulder flexion in detail. Meanwhile, in EOS imaging, the "hands-on-cheeks" (HOC) position is widely used but has not been well investigated. The purpose of this study was to investigate the relative usefulness of FOC and HOC in investigating SVA. MATERIALS AND METHODS: Mean SVA was measured by EOS imaging using standing lateral radiographs of 34 volunteers in four different positions: relaxed (RLX), shoulder flexion at 90° with FOC (FOC90), elbows touching the trunk with FOC (FOCET), and HOC. RESULTS: The mean SVA was 2.0 ± 2.1 cm in RLX; -1.4 ± 3.2 cm in FOC90; -0.5 ± 3.0 cm in FOCET; and -0.2 ± 2.9 cm in HOC. The negative shift from RLX was significantly greater in FOC90 than in FOCET (-3.4 ± 2.2 vs -2.5 ± 2.4 cm; p = 0.0182). The negative shift from RLX in HOC was almost equal to that in FOCET; the difference was 0.3 cm (-2.2 ± 2.2 vs -2.5 ± 2.4 cm; p = 0.2560). CONCLUSION: FOC90 showed a negative SVA shift in comparison with FOCET. The difference in the mean SVA between HOC and FOCET was 0.3 cm, a clinically small difference.