Introduction: In adolescent idiopathic scoliosis of Lenke type 1A, L4 is subdivided into right tilted 1A-R and left tilted 1A-L, with 1A-R considered to have a high risk of distal adding-on (DA). In this study, we investigated factors related to DA in 1A-R, especially vertebral body rotation.

Methods: Included in this analysis were 15 consecutive cases with surgical treatment for Lenke 1A-R. Thirteen cases with both preoperative and 2-year postoperative data were analysed, while two cases were excluded due to an image defect or a lack of follow-up. Patients with and without DA were compared for background, SRS-22, preoperative, immediate postoperative, radiographic parameters 2 years after surgery, and vertebral body rotation using CT.

Results: Four cases with postoperative DA were observed (DA+group). In this group, UIV rotation at the first standing tended to be left rotation (p=0.07), and the UIV rotation had resolved 2 years after surgery. Right rotation and wedging occurred in the lower intervertebral space of the LIV vertebral body (p=0.02). This suggests the DA may have been caused by a compensatory mechanism of right rotation and lateral flexion of the LIV to resolve the remnants of UIV rotation. Of note, Lenke type 1A-R has a long C-curve and the vertebral body rotation within the main curve tends to be unidirectional. Since there is no inflection point for vertebral body rotation within the fixed range, this may be a compensatory phenomenon to balance body axis rotation.

Conclusion: Our results suggest that DA might occur by lateral rotation around LIV to compensate for convolution in the UIV.

Introduction: We retrospectively evaluated differences in the pathophysiology of traumatic cervical spinal cord injury with major bone injury (TCSCI) between teenage patients and over 65 year-old patients.

Methods: Included in the study were a total of 18 teenage and 26 elderly patients with TCSCI evaluated neurologically within 72 hours after injury and with a minimum follow-up time of 24 months. These cases were from 2009 to 2018. Neurological evaluation at initial diagnosis and final follow-up was performed using the American Spinal Injury Association (ASIA) impairment scale (AIS), the ASIA motor score (AMS), and the modified Frankel classification (Fr).

Results: The mean AMS (upper / lower limbs / total) at the first evaluation were 15.33±10.25 / 5.61±13.52 / 20.94±21.03 and 31.92±17.59 / 21.73±23.9 / 53.65±38.62 for the teenage and elderly patients, respectively. The teenage patients showed severe tetraplegia compared with elderly patients. The final AMS were 28.94±15.48 / 21.11±24.59 / 50.06±38.9 and 35.85±16.97 / 26.69±24.38 / 62.54±38.83 in teenage and elderly patients, respectively. However, elderly patients showed higher values in the upper and lower limbs compared with the total AMS improvement ratio between the first and final examination. Teenage patients showed a significantly higher value than the elderly patients (44.15±41.55 and 28.56±40.01, respectively).

Moreover, 100% (7/7) of the teenage patients and 70.59% (12/17) of the elderly patients with incomplete paralysis (AIS B or higher) had achieved independent walking ability (Fr D2 or higher) at the final observation.

Conclusion: Teenage patients showed a significantly higher AMS improvement ratio than elderly patients. These results suggest that the potential for recovery from spinal cord damage in teenage patients may be higher than for elderly patients. Moreover, teenage patients with incomplete paralysis at the first diagnosis can acquire independent walking ability.

Introduction: The purpose of this study was to investigate the usefulness of administering tranexamic acid (TXA) during surgery for adolescent scoliosis.

Methods: The study included a total of 20 cases, comprising 10 cases of TXA administered during surgery and 10 cases without TXA during surgery (controls). The TXA and control groups were matched for age, sex, curve type, preoperative Cobb angle, and operative time. TXA administration involved intravenous injection of 10 mg/kg over 20 minutes before skin incision, followed by sustained administration until the end of skin suture at 1 mg/kg/hr. Differences in intraoperative bleeding, transfusion, and complications were compared between the TXA administration and control groups.

Results: The average bleeding in the TXA administration group was 563 g and in the control group it was 936 g. This difference was not statistically significant. The average transfusion amount in the TXA administration group (153 g) was significantly less than the average amount in the control group (847 g). No complications were observed in either group.

Conclusions: TXA administration may be effective at reducing intraoperative and postoperative hemorrhage during surgery for adolescent scoliosis.

Purpose: The mechanism for odontoid fracture due to low-energy extensional injuries in the elderly is still unclear. In the present study we used finite element analysis to clarify the mechanism of odontoid fracture due to extension injury of the cervical spine in elderly patients.

Methods: We retrospectively reviewed the cases of a 65-year-old female (Case 1), a 77-year-old male (Case 2), and a 73-year-old male (Case 3). Single (axis [C2]) and complex (occipital bone [C0]-atlas [C1]-C2) models were created. The lower surface of C2 was completely fixed, and a horizontal external force of 2,000 N was applied to both the C2 single model and the C0-C1-C2 complex model from the front of C2 and C0. The average bone mineral density of C2, equivalent stress, and the fracture state were investigated. According to the classification system of Anderson et al., the fracture state was classified as follows: type I (oblique fracture at the tip of the tooth process), type II (fracture at the base of the tooth process), and type III (vertebral body fracture).

Results: The average bone mineral density of C2 in cases 1, 2, and 3 was 420 mg/cm³, 610 mg/cm³, and 620 mg/cm³, respectively. Drucker-Prager stress and fracture were observed at the type II fracture site in the C2 single model and in the C0-C1-C2 complex model of cases 1, 2 and 3.

Conclusion: Our findings suggest that an external force of extension to the cervical spine is likely to cause type II odontoid fractures.

Pars interarticularis defect, spondylolisthesis and spondylolysis appear to be similar diseases. However, it is still unclear whether the pars interarticular defect is acquired or congenital. The pars interarticular defect could not be identified in 500 newborns using lumbar CT and X ray. The par interarticular defect has the same features that many young male athletes experience, whereby the low lumbar spine experiences considerable motion stress. These observations suggest a congenital theory for the pars interarticular defect. We report here a 37 year old who presented with multiple par interarticular defects of L4 and spondylolysis of L5 with broad spina bifida of the sacrum and conjoined nerve root. We postulate low par resulting in an uneven congenital distribution of trabeculation and cortication, which is associated with diffuse spina bifida. Pars defect may be caused not only by exercise stress but also by a fragile bone cortex produced during the fetal period.