Introduction: CMEL (Cervical MicroEndoscopic Laminotomy) using a spinal endoscope has been reported as a surgical treatment for cervical myelopathy. In our department, we have introduced a modified ...version (CMEL) of laminectomy. This technique is minimally invasive, but the selective decompression and discectomy may worsen the outcome compared with conventional treatment.Objective: To compare the 1-year results of the CMEL variant and the Kurokawa method in our department, and to clarify the usefulness and problems of the CMEL variant.Methods: The CMEL variant is a method of complete resection of the lamina between the open intervertebral space. The subjects were 31 cases of CMEL variant and 39 cases of Kurokawa method. The study items were operative time, blood loss, complications, postoperative hospital stay, JOA score before and 1 year after surgery, JOACMEQ, and neck pain NRS.Results: There was no difference in mean operative time. Mean blood loss was lower in the CMEL variant. There was no difference in JOA score before and after surgery, and no difference in JOACMEQ except for cervical spine function before surgery. There was no difference in neck pain NRS both preoperatively and postoperatively.Conclusions: The CMEL variant is an excellent technique with postoperative results comparable to those of the Kurokawa method, and also allows early discharge from the hospital due to its minimally invasive nature.
The efficacy and safety of open drain in Microendoscopic laminotmy (MEL) for lumbar spinal canal stenosis were examined. The subjects: 176 patients who underwent MEL. The closed drainage group ...(closed group: 76 cases), the open drainage group (open group: 100 cases). There was no infection, and one emergency operation with acute epidural hematoma was seen in the closed group. The average postoperative bleeding was significantly higher in the open group than in the closed group. The degree of compression of the dural sac was lower in the open group than in the closed group. Lower limb pain occurred more frequently in the open group. In this study, open drainage was suitable for MEL.
Pullout of inserted anchor constitutes one of the pathomechanisms of re-tearing after rotator cuff repair. The purpose of the present study was to investigate the fixation properties of suture ...anchors using 3-dimensional finite element method.
The computer models of three types of anchors (TwinFix Ti, HEALICOIL PK and HEALICOIL RG) were inserted into the isotropic cube model that simulated cancellous bone. In the virtual pullout testing, a tensile load (500 N) along the long axis of the inserted anchor was applied to the site of suture thread attachment to simulate a traction force. The distribution of von Mises equivalent stress, the failure patterns of elements inside the cube and the anchor displacement were compared among the three anchors.
In TwinFix Ti, the highest stress concentration was seen around the anchor threads close to the surface of the cube, which caused element failure at this site. On the other hand, both HEALICOIL PK and HEALICOIL RG demonstrated a high stress concentration as well as element failure around the anchor tip. Comparing the anchor displacement, HEALICOIL RG showed the smallest displacement among the three anchors. The tensile loads that required a 0.1-mm displacement for TwinFix Ti, HEALICOIL PK and HEALICOIL RG were 400 N, 370 N, and greater than 500 N, respectively.
The bony structures close to the footprint surface may be damaged during surgery due to preparation for the bony bed as well as the insertion of anchors. Thus, we assumed that HEALICOIL RG represented the best initial fixation properties among the three anchors tested. Virtual pullout testing using 3-dimensional finite element method could reveal the detailed biomechanical characteristics of each suture anchor, which would be important for shoulder surgeons to improve the clinical outcomes of rotator cuff repair.
Retearing mechanism after transosseous equivalent (TOE) rotator cuff repair has not been fully clarified yet.
The purposes of this study were to compare the stress distribution pattern in the tendon ...stump between knotted and knotless TOE repair and to investigate the role of suture tension applied during medial knot tying using a 3-dimensional finite element (3D-FE) method.
Both knotted and knotless TOE repairs were simulated on the 3D-FE human rotator cuff tear model. Elastic analysis was performed to compare the stress distribution pattern inside the tendon between the two models. The amount of compressive load applied to the medial-row sutures was then changed as 0, 20, 40, 60, 80, and 100 N in the knotted model.
Knotted model demonstrated more distinct stress concentration inside the tendon around medial-row sutures than the knotless model. Mean von Mises equivalent stress in this area in the 0, 20, 40, 60, 80, and 100 N models was 0.26, 0.35, 0.50, 0.70, 1.11, and 1.14 MPa, respectively.
In the knotted TOE repair, tight medial knot tying might cause a high stress concentration around medial knots, which may constitute one of the pathogenetic factors of postoperative retearing at this site.
Incidental durotomy (dural tear) is a common complication of lumbar spine surgery. The purpose of this study was to clarify the anatomical location of and the specific causative factors for ...incidental durotomy during primary lumbar spine surgery.
The authors retrospectively reviewed 1014 consecutive cases involving patients (412 women and 602 men; mean age 57 years; age range 11-97 years) who underwent a surgical procedure for treatment of degenerative lumbar spinal disease at their institution between 2002 and 2008. In total, 1261 disc levels were treated surgically. Disease at the treated levels included 544 disc herniations, 453 instances of spinal canal stenosis without spondylolisthesis, 188 instances of lumbar spinal canal stenosis with spondylolisthesis (degenerative spondylolisthesis), 49 instances of combined stenosis (stenosis with disc herniation), and 22 juxtafacet cysts. In 5 of the treated levels, the condition was classified as "other" disease. Treatment included fenestration with discectomy in 547 levels, fenestration alone in 626, fenestration with resection of juxtafacet cysts in 22, unilateral recapping laminoplasty in 20, posterolateral spinal fusion or posterior lumbar interbody fusion in 17, microscopic discectomy with tubular retractor in 14, and "other" in 15.
Unintended durotomy occurred in 4% of cases and in 3.3% of disc levels. The incidence of dural tear was significantly higher in women (5.6%) than in men (3%). The incidence of dural tear was 2% in disc levels with lumbar disc herniation, 1.8% with lumbar spinal canal stenosis without spondylolisthesis, 9% with degenerative spondylolisthesis, and 18.2% with juxtafacet cysts; the incidence was significantly higher in levels with degenerative spondylolisthesis or levels with juxtafacet cysts, than in those with other diseases. Incidental durotomy occurred in 4 critical anatomical zones, namely, the caudal margin of the cranial lamina, cranial margin of the caudal lamina, herniated disc level, and medial aspect of the facet joint adjacent to the insertion of the hypertrophic ligamentum flavum.
Risk factors for unintended durotomy were female sex, older age, degenerative spondylolisthesis, and juxtafacet cysts. In this study, the authors identified 4 high-risk anatomical zones that spine surgeons should be aware of to avoid dural tears.
Introduction: Middle column injury is a poor prognostic factor for the conservative treatment of osteoporotic vertebral fractures (OVF). The effects of the degree of middle column injury and external ...fixation methods (body cast, hard, or soft brace) on bone union and deformity of the vertebral body were examined.Methods: Of the patients with fresh thoracolumbar OVF without paralysis who were hospitalized and treated within 1 month of onset, 224 were followed up after 1 year. The degree of middle column injury was evaluated by flexion CT, reflecting the loading position, and the patients were divided into four groups according to the occupancy rate of the bone fragments that had entered the spinal canal (occupancy rate). Results: In Group A (occupancy rate >50%: 7 cases), the union rate was significantly higher in a body cast than in a hard brace (p < 0.05); in Groups B and C (occupancy rates 30%-50% and <30%: 26 and 164 cases), the union rate was significantly higher in a body cast than in a soft brace (p < 0.01 and 0.05). There was a trend toward improvement in the anterior vertebral margin height and fragment occupancy in the spinal canal in Groups A, B, and C, respectively.Conclusions: A body cast is useful for conservative treatment of OVF with middle column injury.
The basic surgical treatment for spinal canal lesion of lumbar spinal canal stenosis is decompression surgery. However, the endpoints of decompression surgery are unclear in many procedure manuals. ...The purpose of this study was to identify the location of spinal canal stenosis, posterior compression factors, and their relationship to the endpoints of the surgical procedure. The patients were 100 cases, 167 vertebrae, who underwent endoscopic laminectomy for spinal canal stenosis at our institution. Lumbar degenerative spondylolisthesis was found in 47 vertebrae (28%). Nerve compression sites were classified as high in the intervertebral disc, cephalad, or caudal to the intervertebral disc. Dorsal compression factors were also identified. Results. Nerve compression sites included cephalad to intervertebral disc in 3%, intervertebral disc only in 81%, intervertebral disc to caudal in 13%, cephalad to caudal in 1%, and caudal only in 2%. 98% of the cases included intervertebral disc. Posterior compression factors were ligamentum flavum in 91% and lipomatosis in 8%. Decompression surgery for lumbar spinal canal stenosis should be performed using the intervertebral disc as a guide for decompression and removal of the ligamentum flavum and lipomatosis at the same site.
For lumbar spinal canal stenosis, we only perform minimally invasive decompression surgery in all patients with or without degenerative spondylolisthesis. The aim of this study was to examine and ...validate the 1-year results of patients who underwent decompression surgery only, focusing on the presence or absence of degenerative spondylolisthesis.Methods: 200 patients with lumbar spinal canal stenosis operated on only the L4/5 vertebrae were divided into 85 patients in the non-degenerative spondylolisthesis group (NDS group), 95 patients in the Meyerding classification 1st degree group (DS1 group) and 20 patients in the 2nd degree group (DS2 group). Operative technique, operative time, blood loss, perioperative complications, reoperation rate, JOA score, ODI, JOABPEQ and Lumbago/lower limb pain NRS were compared.Results: There were no differences in operative time or blood loss between the three groups. There was one dural injury in the DS1 group and one re-operation in the NDS group; JOA score and JOABPEQ did not differ between the three groups; DS2 group had inferior results in postoperative ODI and lower limb NRS; DS2 group had some inferior results. However, the DS2 group was considered to have a good surgical outcome based on the reoperation rate, the improvement in ODI and the significant improvement in lower limb pain NRS. The presence or absence of a spondylolisthesis was less involved in the short-term results and did not suggest the need for fusion surgery.
