Shoichiro Ohyama

Clinical Outcome of Cervical Laminoplasty and Postoperative Radiological Change for Cervical Myelopathy With Degenerative Spondylolisthesis.

Study Design. A retrospective cohort study with prospectively collected data. Objective. The aim of this study was to investigate the clinical and radiological outcome of cervical laminoplasty for cervical myelopathy with degenerative spondylolisthesis. Summary of Background Data. The presence of spondylolisthesis is thought to represent segmental instability in spine. Cervical laminoplasty is a common decompression surgery for cervical myelopathy, but its clinical result for cervical spondylolisthesis has not been well studied. Methods. One hundred seventeen patients who underwent cervical laminoplasty for degenerative cervical myelopathy were included. Japanese Orthopaedic Association score (JOA score) and visual analog scale of neck pain, upper arm pain and numbness were evaluated before surgery, and at scheduled time points after surgery. Spondylolisthesis was defined as more than 2 mm slip on plain radiograph, and the clinical results were compared between the patients with spondylolisthesis (group S) and without spondylolisthesis (group C). In the patients with spondylolisthesis, the slip distance and translational motion between flexion and extension was examined on plain lateral radiograph before surgery and 2 years after surgery. Results. Degenerative cervical spondylolisthesis was found in 49 levels of 33 patients (28.2%), and the average age of group S was significantly higher than group C. JOA score and each VAS score was significantly improved after surgery in both groups. Average JOA score of group S was significantly lower than group C at every time points, but the recovery rate was similar between the two groups. In the level of spondylolisthesis, average slip distance did not changed, but average translational motion was significantly decreased in 2years after surgery. Conclusion. Cervical spondylolisthesis was common in elderly patients. The clinical outcome in group S was comparable with group C, and the level with spondylolisthesis has been stabilized after surgery. Thus, laminoplasty can be a treatment option even for cervical myelopathy with degenerative spondylolisthesis. Level of Evidence: 3

Anterior Cervical Discectomy and Fusion Provides Better Surgical Outcomes Than Posterior Laminoplasty in Elderly Patients With C3-4 Level Myelopathy.

Study Design. Retrospective analyses of prospectively collected data regarding 180 patients with cervical spondylotic myelopathy (CSM). Objective. To detect the characteristics of C3-4 level CSM in elderly patients (C3-4CSM) (main analysis) and to validate the postoperative outcomes of anterior cervical discectomy and fusion (ACDF) and of laminoplasty (LAMP) (subgroup analysis). Summary of Background Data. It remains unclear which surgical technique offers the best outcomes for CSM. Methods. The main analysis included 180 patients with CSM, divided into two groups (C3-4CSM group, n = 46; conventional CSM group, n = 134) according to the findings of the preoperative physical examination and magnetic resonance imaging. The subgroup analysis included 46 patients with C3-4CSM, divided into two groups (ACDF group, n = 21; LAMP group, n = 25) according to surgical technique. Preoperative demographics and postoperative outcomes were compared. Results. The age at surgery was higher, disease duration was shorter, and preoperative Japanese Orthopaedic Association (JOA) score was lower in the C3-4CSM group than in the conventional CSM group. Although the C3-4 range of motion was significantly higher, that of other levels was significantly lower in the C3-4CSM group. The anteroposterior diameter for levels C3-C7 was significantly larger in the C3-4CSM group. In the subgroup analysis using the repeated-measures analysis of variance, the postoperative JOA scores, and visual analog scale of neck pain were significantly better in the ACDF group. Conclusion. Higher age, shorter disease duration, and worse JOA scores appear to be characteristic of C3-4CSM. In the management of C3-4CSM, ACDF provided better surgical outcomes than did LAMP; hypermobility at the C3-4 level, a radiological characteristic of C3-4CSM, may be one of key factors affecting surgical outcome. The chance to diagnose C3-4CSM is increasing with the increasing healthy life expectancy. To enable effective resolution of symptoms, C3-4CSM must be distinguished from conventional CSM. Level of Evidence: 4

Cervical lordotic alignment following posterior spinal fusion for adolescent idiopathic scoliosis: reciprocal changes and risk factors for malalignment.

OBJECTIVE Numerous reports have been published on the effectiveness and safety of correction of the coronal Cobb angle and thoracolumbar sagittal alignment in patients with adolescent idiopathic scoliosis (AIS). Suboptimal sagittal alignment, such as decreased thoracic kyphosis (TK), after corrective surgery, is a possible cause of lumbar or cervical spinal degeneration and junctional malalignment; however, few reports are available on reciprocal changes outside of the fused segments, such as the cervical lordotic angle (CLA). This study aimed to investigate the relationship between the perioperative CLA and other radiographic factors or clinical results in AIS, and to identify independent risk factors of postoperative cervical hyperkyphosis. METHODS A total of 51 AIS patients who underwent posterior spinal fusion with the placement of pedicle screw (PS) constructs at thoracic levels were included in the study. Clinical and radiographic follow-up of patients was conducted for a minimum of 2 years, and the postoperative course was evaluated. The authors measured and identified the changes in the CLA and other radiographic parameters using whole-spine radiography, with the patient in the standing position, performed immediately before surgery, 2 weeks after surgery, and 2 years after surgery. The postoperative cervical hyperkyphosis group included patients whose CLA at 2-year follow-up was smaller than -10°. The reciprocal changes of the CLA and other parameters were also investigated. Univariate and multivariate analyses were conducted to determine the associated risk factors for postoperative cervical hyperkyphosis. RESULTS This study comprised 48 females and 3 males (mean age 16.0 years). The mean follow-up period was 47 months (range 24-90 months). The main coronal thoracic curve was corrected from 54.6° to 16.4°, and the mean correction rate was 69.8% at 2 years. The CLA significantly increased from the mean preoperative measurement (-5.4° ± 14°) to the 2-year follow-up measurement (-1.7° ± 11°) (p = 0.019). Twelve of the 51 patients had postoperative cervical hyperkyphosis. This group exhibited significantly smaller preoperative CLA and TK measurements (p = 0.001 and 0.004, respectively) than the others. After adjusting for confounding factors, preoperative CLA less than -5° and preoperative TK less than 10° were significantly associated with postoperative cervical hyperkyphosis (p < 0.05; OR 12.5 and 8.59, respectively). However, no differences were found in the clinical results regardless of cervical hyperkyphosis. CONCLUSIONS The CLA increased significantly from preoperatively to 2 years after surgery. Preoperative small CLA and TK measurements were independent risk factors of postoperative cervical hyperkyphosis. However, there was no difference in the clinical outcomes regardless of cervical hyperkyphosis.

The incidence of nerve root injury by high-speed drill can be reduced by chilled saline irrigation in a rabbit model

Aims We aimed to evaluate the temperature around the nerve root during drilling of the lamina and to determine whether irrigation during drilling can reduce the chance of nerve root injury. Materials and Methods Lumbar nerve roots were exposed to frictional heat by high‐speed drilling of the lamina in a live rabbit model, with saline (room temperature (RT) or chilled saline) or without saline (control) irrigation. We measured temperatures surrounding the nerve root and made histological evaluations. Results In the control group, the mean temperature around the nerve root was 52.0°C (38.0°C to 75.5°C) after 60 seconds of drilling, and nerve root injuries were found in one out of 13 (7.7%) immediately, three out of 14 (21.4%) at three days, and 11 out of 25 (44.0%) at seven days post‐operatively. While the RT group showed a significantly lower temperature around the nerve root compared with the control group (mean 46.5°C; 34.5°C to 66.9°C, p < 0.001), RT saline failed to significantly reduce the incidence of nerve root injury (ten out of 26; 38.5%; odds ratio (OR) 0.96; 95% confidence interval (CI) 0.516 to 1.785; p = 0.563). However, chilled saline irrigation resulted in a significantly lower temperature than the control group (mean 39.0°C; 35.3°C to 52.3°C; p < 0.001) and a lower rate of nerve root injury (two out of 21; 9.5%, OR 0.13; 95% CI 0.02 to 0.703, p = 0.010). Conclusion Frictional heat caused by a high‐speed drill can cause histological nerve root injury. Chilled saline irrigation had a more prominent effect than RT in reducing the incidence of the thermal injury during extended drilling.

Impact of Hemodialysis on Surgical Outcomes and Mortality Rate After Lumbar Spine Surgery: A Matched Cohort Study

Introduction Despite ongoing improvements in both dialysis and surgical techniques, spinal surgery in patients undergoing hemodialysis (HD) is a challenge to surgeons because of the high mortality rate. However, no previous studies have examined clinical outcomes after lumbar surgery in HD patients. The purpose of this study is to compare clinical outcomes and complication rates after lumbar spinal surgery in patients with or without hemodialysis. Methods This retrospective, matched cohort study was conducted to compare surgical outcomes between HD vs non-HD patients who underwent lumbar surgery at our hospital. Controls were individually matched to cases at a ratio of 1:2. Clinical outcomes, complications, and mortality rates were compared between the two groups. Results Twenty-nine patients in the HD group and 57 in the non-HD group were included in the current study. Five patients in the HD group died during the follow-up period, whereas no patients died in the non-HD group (mortality rate, 17.2% vs. 0%, P = 0.003). Japanese Orthopaedic Association (JOA) scores were significantly less improved in the HD group than in the non-HD group (11.9 vs. 14.2 preoperatively, P = 0.001; 19.9 vs. 25.1 at final follow-up, P < 0.001). Five patients underwent repeat surgery in the HD group, which was significantly higher than the non-HD group (17.2% vs. 3.5%, P = 0.041). Conclusions The current study indicates that patients undergoing HD had poor outcomes after lumbar spinal surgery. Moreover, 5 of 29 patients died within a mean 2.4-years follow-up. The indications for lumbar spine surgery in HD patients must be carefully considered because of poor surgical outcomes and high mortality rate.

Anatomical analysis of the human ligamentum flavum in the thoracic spine: Clinical implications for posterior thoracic spinal surgery

BACKGROUND Knowledge of the ligamentum flavum anatomy is important for posterior spinal surgery. However, only a few studies have evaluated the relationship between the thoracic ligamentum flavum and its surrounding structures. This study aimed to clarify the anatomy of the thoracic ligamentum flavum. METHODS The entire spines from 20 human embalmed cadavers were harvested in an en bloc fashion. All pedicles were vertically cut using a thread bone saw, and the ligamentum flavum from T1-T2 to T12-L1 was painted using a contrast agent containing an iron powder. Computed tomography was performed, and the ligamentum flavum shape (width and height) and its relationship with the spinal bony structures (lamina and foramen height percentage covered by the ligamentum flavum) were analyzed using a three-dimensional analyzing software. RESULTS The thoracic ligamentum flavum height and width gradually increased from T1-T2 to T12-L1. The caudal lamina height ventrally covered by the ligamentum flavum also increased gradually from the upper (T1-T2: 31.7%) to the lower levels (T12-L1: 41.7%); however, the cranial lamina height dorsally covered by the ligamentum flavum decreased from the upper (12.6%) to the lower levels (4.3%). The neural foramen was covered by the ligamentum flavum in all thoracic spines, except for T1-T2. Between T2-T3 and T12-L1, approximately 50% of the cranial part of the foramens was covered by the ligamentum flavum; however, the caudal part was not covered. CONCLUSIONS This study using contrasted ligamentum flavum and reconstructed CT provided information on the thoracic ligamentum flavum shape and its relationship with the bony structures. The ventral ligamentum flavum coverage of the cranial lamina increase from cranial to caudal, and the cranial half of the neural foramen is covered by the ligamentum flavum below T2-T3 but not in T1-T2. These findings would help spine surgeons to design and perform safe and adequate posterior thoracic spinal surgeries.

Comparison of minimally invasive decompression and combined minimally invasive decompression and fusion in patients with degenerative spondylolisthesis with instability

Posterior lumbar interbody fusion with cortical bone trajectory (CBT-PLIF) is a form of minimally invasive decompression and fusion, whereas microendoscopic laminotomy (MEL) is a form of minimally invasive decompression surgery. No study has compared the clinical outcomes of the two methods for patients who have degenerative spondylolisthesis (DS) with instability. In this study, CBT-PLIF and MEL were both offered to 64 patients who met the inclusion criteria. Each patient then selected his or her preferred treatment. Twenty patients received CBT-PLIF. They were matched to 30 of the 44 patients receiving MEL based on age, sex, disease duration, and surgical levels. The 20 patients with CBT-PLIF formed the CBT group and the 30 matched patients with MEL formed the MEL group. At 2 years of follow-up, Japanese Orthopaedic Association scores improved to 72.6% and 70.5% in the CBT and MEL groups, respectively. The difference in scores was not statistically significant. Further, improvements in visual analogue scale scores for back and leg symptom did not differ significantly between the two groups. Regarding complications, 1 CBT-group patient (5%) had adjacent-segment degeneration and 7 MEL-group patients (23%) had same-segment degeneration. Three CBT-group patients (15%) and 5 MEL-group patients (16%) required reoperation within the follow-up period. In summary, among patients who had DS with instability, MEL and CBT-PLIF offered comparable clinical outcomes at 2 years of follow-up. Although the rate of segmental degeneration was relatively high in the MEL group, both groups had similar reoperation rates.

Mechanical stress induces elastic fibre disruption and cartilage matrix increase in ligamentum flavum

Lumbar spinal stenosis (LSS) is one of the most frequent causes of low back pain and gait disturbance in the elderly. Ligamentum flavum (LF) hypertrophy is the main pathomechanism of LSS, but the reason for its occurrence is not clearly elucidated. In this study, we established a novel animal model of intervertebral mechanical stress concentration and investigated the biological property of the LF. The LF with mechanical stress concentration showed degeneration with elastic fibres disruption and cartilage matrix increase, which are similar to the findings in hypertrophied LF from patients with LSS. By contrast, decreased Col2a1 expression was found in the LF at fixed levels, in which mechanical stress was strongly reduced. These findings indicate that mechanical stress plays a crucial role in LF hypertrophy through cartilage matrix increase. The findings also suggest that fusion surgery, which eliminates intervertebral instability, may change the property of the LF and lead to the relief of patients’ symptoms.