Zygapophyseal, or facet, joints are complicated biomechanical structures in the spine, with a complex three-dimensional (3D) anatomy, variable mechanical functions in different spinal movements, and effects on the overall spine mechanical behavior. The 3D morphology of the facet joint is linked to its biomechanical function. Failure of the biomechanical function of the facet joint leads to osteoarthritic changes in it and is implicated in other spinal disorders such as degenerative spondylolisthesis. Facet joints and intervertebral disk are part of an entity called the spinal motion segment, the three-joint complex, or the articular triad. Functioning together, the structures in the spinal motion segments provide physiological spinal motion, while protecting the spine by preventing activities that can be injurious. Loss of intervertebral disk height associated with disk degeneration affects the mechanical behavior of facet joints. Axial compressive load transmission through the tip of the inferior articular process can occur in the extended position, especially with reduced disk height, which may cause capsular impingement and low back pain. The 3D curvature of the articular surfaces and capsular ligaments play important roles in different spinal positions. In this review article, we will summarize the anatomy of the lumbar facet joint relevant to its biomechanical function and biomechanical behavior under different loading conditions.
Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.
Introduction: To carry out ultrasound-guided cervical nerve root block (CNRB) safely, we investigated the frequency of risky blood vessels around the target nerve root and within the imaginary needle pathway in the actual injecting position.
Methods: 30 patients (20 men, 10 women) with cervical radiculopathy who received ultrasound-guided CNRB were included in this study. We defined a risky blood vessel as an artery existing within 4 mm from the center of the target nerve root or located in the range of 2 mm above or below the imaginary needle pathway.
Results: Using the color Doppler method, the frequency of a risky blood vessel existing around 4 mm from the center of the C5 nerve root was 3.3% (1/30), whereas it was 3.3% (1/30) for the C6 nerve root and 23.3% (7/30) for the C7 nerve root. Hence, the C7 level had more blood vessels close to the target nerve root compared to the C5 and C6 levels, but there was no significant difference (p = 0.0523). On the other hand, the frequency of a risky blood vessel existing within 2 mm above and below the imaginary needle pathway was 3.3% (1/30) for the C5 nerve root, whereas it was 3.3% (1/30) for the C6 nerve root and 10.0% (3/30) for the C7 nerve root. The C7 level had more blood vessels within the needle pathway compared to the C5 and C6 levels, but there was no significant difference (p = 0.301).
Conclusions: To reduce the risk of unintended intravascular injections, more careful checking for the presence or absence of blood vessels at the C7 level using color Doppler is necessary.
Introduction: In drop finger, the extension of the finger is limited, although the wrist can be flexed dorsally. There have been no well-organized reports on drop finger pattern caused by cervical nerve root disorder. Moreover, diagnosis and treatment are delayed because of the inability to distinguish cervical radiculopathy from peripheral nerve disease. This study aimed to clarify the operative outcome of microscopic cervical foraminotomy (MCF) for cervical radiculopathy presenting drop finger and to investigate whether our classification based on drop finger patterns is useful retrospectively.
Methods: Overall, 22 patients with drop finger who underwent MCF were included. Grip power (GP) and longitudinal manual muscle test (MMT) score of each finger were examined. Drop finger patterns were classified as types I, II, and III. In type I, the extension disorders of the middle and ring fingers are severe and those of index and little fingers are mild. In type II, the extension disorders are severe from the little finger and slightly to index finger. In type III, the extension disorder is consistently severe in all fingers. Perioperative nerve root disorder and paralysis degree were investigated for all types.
Results: The mean GP was significantly postoperatively improved in all 22 patients. The mean MMT score would benefit from exact data for almost all muscles, except the abductor pollicis brevis at the last follow-up. However, pre- and postoperative paralyses were severe in type III patients. C7 nerve root disorder was confirmed in 5/6 type I patients and C8 nerve root disorder in 12/13 type II and 3/3 type III patients.
Conclusions: The operative results of MCF were relatively good, except in type III patients. As a certain tendency was confirmed between the drop finger types and injured nerve roots, our classification may be useful in reducing misdiagnosis and improving the operative results to some extent.
Introduction: SHILLA and growth rods are two main surgical correction techniques for patients with early-onset scoliosis. There have been some comparative studies between the two techniques, where a comparison was made between deformity identifying characteristics such as Cobb angle, apical vertebral translation, coronal balance, spinal length gain, etc. However, the SHILLA procedure experiences loss of correction or the reappearance of deformity through crankshafting or adding-on (e.g., distal migration). The current study identifies a solution with a modified approach to SHILLA (which could help in dynamically remodulating the apex of the deformity and mitigating loss of correction) and presents comparative correction data against the long-established traditional growth rod system.
Methods: The active apex correction (APC) group consisted of 20 patients and the growth rod group consisted of 26 patients, both with the same inclusion and exclusion criteria. The APC surgical procedure involved a modified SHILLA technique, that is, insertion of pedicle screws in the convex side of the vertebrae above and below the wedged one for compression and absence of apical fusion.
Results: There were no statistical differences between the various spinal parameters (namely, Cobb angle, apical vertebral translation, sagittal balance, and spinal length gain) of the two groups. However, significant differences existed for coronal balance, which in part may have been due to differences in its pre-op value between the two groups.
Conclusions: APC and the traditional growth rod system showed similar deformity correction parameters at current follow-ups; however, the latter requires multiple surgeries to regularly distract the spine.
Introduction: Fixed abduction and/or adduction deformities of the hip joint may cause pelvic obliquity with subsequent development of secondary lumbar scoliosis. However, the relationships between the magnitude of a fixed angle (either abduction or adduction) of the hip and the direction of pelvic tilt and lumbar scoliosis remain unclear. The purpose of this study was to investigate the coronal alignment of the lumbar spine and pelvis in patients with ankylosed hips.
Methods: A total of 56 patients were analyzed, including 17 males and 39 females, with an average age of 65 years (range: 45 to 80 years). Regarding the coronal spinopelvic alignment, the following parameters were measured: the degree of lumbar scoliosis (LS; Cobb angle), pelvic obliquity (PO), and ankylosed hip angle (AHA). The PO and AHA were defined as the angle between the inter-teardrop line and a horizontal line, respectively, and the long axis of the femur on the side of the ankylosed hip. For each parameter, correlations between the parameters were evaluated using a regression analysis. A P value of <0.05 was considered significant.
Results: Positive linear correlations were observed between the AHA and direction of the PO angles (r = 0.831, p<0.01), the AHA and direction of the LS angles (r = 0.770, p<0.01), and the directions of the PO and LS angles (r = 0.832, p<0.01).
Conclusions: This study provides evidence to suggest that, in patients with ankylosed hips, the abduction position is positively correlated with the downward PO and the convexity of the LS toward the AH side. In contrast, the adduction position is positively correlated with these results on the opposite side.
Introduction: The aims of this study were to investigate how adjacent segment degeneration (ASD) occurs at the proximal and distal segments after L3-L5 fusion surgery, namely, floating fusion, and to identify the risk factors for ASD in patients who undergo this surgery.
Methods: Fifty patients who underwent floating fusion surgery at vertebrae L3-L5 and developed ASD were enrolled. The following parameters were evaluated: body mass index (BMI), diabetes status, dialysis status, lumbar lordosis, segmental lordosis between the L2 upper endplate and the L3 lower endplate, disc height, Cobb's angle, apical vertebral rotation using the Nash and Moe classification method, preoperative disc degeneration, surgical procedures, and the upper instrumented vertebra (UIV) tilt angle. The UIV tilt angle was defined as positive when the anterior side was directed caudally.
Results: Twenty-two (44%) of the 50 patients showed cephalad radiographic ASD (RASD) and 5 patients (10%) showed caudad RASD. Clinically symptomatic ASD was found at L2-L3 in 4 patients (8%) and at L5-S1 in 2 patients (4%). All the patients with clinically symptomatic cephalad ASD underwent revision procedures for radiculopathy or claudication because of degenerative pathology at L3-L4. Multivariate regression analysis showed a significant association of the absolute value of UIV tilt angle (mean |UIV tilt|) with cephalad RASD (odds ratio 1.09, p = 0.038). Receiver-operating characteristic curve analysis showed a significant association of |UIV tilt| >10.3° with RASD (sensitivity 67.9%, specificity 77.3%, area under the curve [AUC] 0.675).
Conclusions: RASD was more likely to occur at the adjacent segment on the cephalad side than at the adjacent segment on the caudad side after two-segment floating fusion of L3-L5. A preoperative UIV tilt angle >10° or UIV tilt < −10° was a risk factor for RASD.
Introduction: Despite preserving lumbar disc mobility, spinal sagittal, and/or coronal alignment might ultimately impede surgical success. The purpose of this study was to elucidate the effects of spinal alignment on lumbar disc degeneration after 5 or more years in adolescent idiopathic scoliosis (AIS) patients who underwent spinal fusion.
Methods: Subjects were 49 AIS patients who underwent posterior spinal fusion without lumbar curve fusion. The inclusion criteria were the following: 1) Lenke type 1A, 1B, 2A or 2B, 2) age 10 to 19 years at the time of operation, and 3) minimum 5-year follow-up. The exclusion criteria were the following: 1) diagnosed as other than AIS, 2) history of lumbar disc herniation and spondylolysis, 3) subsequent surgery, and 4) history of surgery before AIS surgery. Nineteen patients agreed to participate in this research. X-rays, lumbar MRI, and questionnaires were evaluated. Disc degeneration in non-fused segments was defined as Pfirrmann grade 3 or higher. Patients with disc degenerations at the final observation (DD[+] group) were compared to those without disc degenerations (DD[−] group).
Results: There were no significant differences in the preoperative or postoperative 1-week X-ray parameters between both groups. The lumbar curve was significantly larger in the DD[+] group compared with the DD[−] group at the final observation (DD[+]: 16.8 degrees, DD[−]: 10.4 degrees, p = 0.035). The sagittal vertical axis (SVA) was significantly larger in the DD[+] group compared with the DD[−] group at the final observation (DD[+]: −4.4 mm, DD[−]: −34.3 mm, p = 0.006). SRS-22 function, self-image, and satisfaction scores were lower in the DD [+] group compared with the DD[−] group at the final observation.
Conclusions: The patients with DD had significantly larger lumbar curve and SVA with lower SRS-22 function, self-image, and satisfaction scores at the final observation. Even though the non-fused segments were preserved, spinal alignments of non-fused lumbar curve affect the DDs.
Introduction: Surgical treatment of osteoporotic vertebral fracture (OVF) often involves older patients with various comorbidities; thus, attending physicians must pay special attention to the invasiveness of surgical procedures and possible perioperative complications. In this retrospective observational study, we investigated the relationship between OVF and diffuse idiopathic skeletal hyperostosis (DISH) by examining the clinical characteristics and surgical outcomes.
Methods: Subjects comprised 26 patients (14 men, 12 women) who underwent surgical treatment for OVF complicated by DISH. Vertebral injuries affected the thoracolumbar transitional vertebrae in 18 patients and the middle and lower lumbar vertebrae in eight patients. The clinical characteristics, surgical results, radiological assessments, and outcomes were evaluated on the basis of the levels of affected vertebrae and whether anterior column reconstruction (ACR) was performed.
Results: Visual Analog Scale (VAS) measurements improved from an average of 69.7 mm before surgery to 21.3 mm after surgery. 14 patients had neurological deficits, who exhibited improvements by one or more steps on the Frankel scale after surgery. Activities of daily living (ADLs) were maintained during the six-month period following surgery in 23 patients. Comorbidity was observed in 22 patients. 14 patients had perioperative complications, and six required additional surgery. Both operating time and blood loss volume were significantly higher in patients in the middle and lower lumbar vertebrae and ACR groups. Postoperative correction loss was also significantly lower in the ACR group.
Conclusions: Favorable degrees of improvement in neurological deficits and VAS were observed following surgery in patients with OVF complicated by DISH, and postoperative ADLs were maintained in 92% of the patients. Elderly men frequently presented with comorbidities, and the frequencies of patients with perioperative complications and those requiring additional surgery were high.
Introduction: Leptomeningeal metastasis (LM) is known to demonstrate a very poor prognosis. The purpose of this study was to evaluate the prognostic factors in LM cases diagnosed by spinal magnetic resonance imaging (MRI).
Methods: We retrospectively analyzed 19 patients with LM detected by spinal MRI between 2010 and 2017.
Results: The primary tumors were breast carcinoma (n = 7), lung carcinoma (n = 6), lymphoma (n = 3), colorectal carcinoma (n = 2), and gastric carcinoma (n = 1). Thirteen patients exhibited preceding brain metastasis, and 11 of these exhibited metastasis in the posterior fossa. Ten patients exhibited limb paralysis. Performance status at diagnosis was 0-1 in 6 patients, 2 in 9 patients, and 3-4 in 4 patients. Testing of cerebrospinal fluid revealed malignant cells in 9 patients.
On MRI, 11 patients demonstrated disseminated tumor lesions at the cervical cord level, 15 patients at the thoracic cord level, and 11 patients below the conus level. Eleven patients received radiation therapy, while intrathecal chemotherapy was performed in 9 patients.
Univariate analysis revealed cervical cord level lesions, intrathecal chemotherapy, paralysis, and performance status as prognostic factors. Multivariate analysis identified existence of a cervical cord lesion as associated with a poor prognosis (hazards ratio (HR) 3.46, 95% confidence interval (CI) 1.12-12.2), while administration of intrathecal chemotherapy was associated with a good prognosis (HR 0.15, 95% CI 0.026-0.67).
Conclusions: In LM patients, cervical cord level lesions are a negative factor for prognosis, and performance of intrathecal chemotherapy is a positive factor for prognosis.
Introduction: Lateral lumbar interbody fusion (LLIF) is becoming a more common surgical treatment option for adult degenerative lumbar conditions. LLIF is a mini-open access technique with wound retractors, and postoperative hematoma due to segmental vessels injury is reported. Thus, it is considered that there is a need to conduct detailed preoperative examinations to identify where the lumbar vessels are. As far as we know, there are only a few studies investigating the location of the lumbar arteries. This study evaluates the anatomical position of lumbar arteries using magnetic resonance imaging (MRI).
Methods: We studied 101 MRIs of patients with lumbar disease. The length from the upper and lower end plates of the vertebra to the lumbar arteries was measured. The measurement was conducted with coronal MRI images of every quarter slice of L1 to L4 vertebrae. We also investigated sagittal MRI images to determine whether the lumbar vessels are located on intervertebral disc in each level from L1/2 to L5/S1.
Results: The lumbar vessels are not always located at the center of the vertebrae. Some lumbar vessels are located within 8 mm from the end plates. Especially in L4, the lumbar vessels tended to go down from the anterior cranial side to the posterior caudal side (P < 0.01). 8, 24, and 54 lumbar vessels are located at the anterior quarter, the center, and the posterior quarter slice of the vertebrae, respectively, in L4. There were seven lumbar vessels in total located on the vertebral disc level.
Conclusions: It is necessary to investigate where the lumbar arteries are located to prevent its injury in LLIF, because the lumbar artery is not always located at the center of a vertebra. MRIs may provide a valuable information to avoid vascular injury during LLIF.
Introduction: To analyze the extent to which various types of orthoses can restrict motion of the lumbar spine and provide basic evidence regarding the optimal orthosis for conservative treatment of lumbar spondylolysis (LS), particularly. Although several orthoses have been developed and applied for LS with better outcomes for bony healing, basic data regarding which is optimal are still lacking.
Methods: Ten healthy voluntary participants were included in this study. Lumbar spine range of motion (ROM) was analyzed using a three-dimensional motion capture system (NEXUS 2.2, Vicon Motion Systems Ltd., UK) under five conditions wearing no orthosis (NB) and four types of lumbar-sacral orthoses (LSO): custom-made hard LSO (HO), soft LSO supported by four aluminum stays and a custom-molded back cast-panel named "Return to Sports" braces (RS), custom-made soft LSO known as Damen type elasticity corset (DC), and off-the-shelf soft LSO.
Results: HO showed the highest restriction of motion in all directions than the others. Especially, ROM of rotation and side bending were reduced to 58.3% and 63.6% compared with NB, respectively. The other three LSOs showed significantly higher restriction in extension, rotation, and side bending than NB. In flexion and side bending, DC showed significantly higher restriction than NB.
Conclusions: HO showed high restriction in all directions. RS showed higher restriction in extension than NB and less restriction in flexion and side bending than other custom-made LSOs. DC was the only soft LSO showing higher restriction than NB in flexion.
Introduction: Cerebrospinal fluid (CSF) leak is a common complication of surgery involving the lumbar spine. However, although there are various therapeutic options for CSF leak, there is currently no optimal technique, and the choice of therapy often depends on the surgeon's cumulative experience. The aim of this study was to describe the successful treatment of CSF leakage using blood injection therapy along the drain removal tract.
Technical Note: We enrolled 7 consecutive patients who underwent lumbar surgery at our institute. The surgeries performed included decompression in two patients (one microendoscopic surgery), fusion in four, and an epidural cyst resection in one. After finding a CSF leak, we injected about 10 ml of blood from the patient into the drain tract. CSF leak did not recur after the blood injection in any of the seven patients. Following just one day of bed rest, the symptoms of intracranial hypotension disappeared with no instances of worsened symptoms of back pain, lower limb pain or fever.
Conclusions: We propose this route of blood injection therapy as a novel method for the treatment of CSF leak after lumbar surgery.