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Yoram Anekstein - Top 30 Publications

The Proprioceptive System Regulates Morphologic Restoration of Fractured Bones.

Successful fracture repair requires restoration of bone morphology and mechanical integrity. Recent evidence shows that fractured bones of neonatal mice undergo spontaneous realignment, dubbed "natural reduction." Here, we show that natural reduction is regulated by the proprioceptive system and improves with age. Comparison among mice of different ages revealed, surprisingly, that 3-month-old mice exhibited more rapid and effective natural reduction than newborns. Fractured bones of null mutants for transcription factor Runx3, lacking functional proprioceptors, failed to realign properly. Blocking Runx3 expression in the peripheral nervous system, but not in limb mesenchyme, recapitulated the null phenotype, as did inactivation of muscles flanking the fracture site. Egr3 knockout mice, which lack muscle spindles but not Golgi tendon organs, displayed a less severe phenotype, suggesting that both receptor types, as well as muscle contraction, are required for this regulatory mechanism. These findings uncover a physiological role for proprioception in non-autonomous regulation of skeletal integrity.

The Proprioceptive System Masterminds Spinal Alignment: Insight into the Mechanism of Scoliosis.

Maintaining posture requires tight regulation of the position and orientation of numerous spinal components. Yet, surprisingly little is known about this regulatory mechanism, whose failure may result in spinal deformity as in adolescent idiopathic scoliosis. Here, we use genetic mouse models to demonstrate the involvement of proprioception in regulating spine alignment. Null mutants for Runx3 transcription factor, which lack TrkC neurons connecting between proprioceptive mechanoreceptors and spinal cord, developed peripubertal scoliosis not preceded by vertebral dysplasia or muscle asymmetry. Deletion of Runx3 in the peripheral nervous system or specifically in peripheral sensory neurons, or of enhancer elements driving Runx3 expression in proprioceptive neurons, induced a similar phenotype. Egr3 knockout mice, lacking muscle spindles, but not Golgi tendon organs, displayed a less severe phenotype, suggesting that both receptor types may be required for this regulatory mechanism. These findings uncover a central role for the proprioceptive system in maintaining spinal alignment.

Clinical and radiological factors affecting progressive collapse of acute osteoporotic compression spinal fractures.

Osteoporotic compression spine fractures have a different clinical course and outcomes when compared to spinal fractures occurring in the younger population. Only a few studies have investigated the risk factors for progressive osteoporotic compression spine fractures. The purpose of this study was to investigate clinical and radiological factors related to progressive collapse following acute osteoporotic compression spine fractures. We retrospectively identified all patients treated for thoracolumbar fractures in our institution between January 2008 and July 2013. Included cases were examined by plain radiographs and CT scans. For each patient we classified the fracture according to the AOSpine Thoracolumbar Spine Injury Classification System. The difference between initial and final height loss and initial and final local kyphosis was documented as height loss difference and kyphotic angle difference. The presence of old fractures and intravertebral cleft were also documented. The study included 153 patients, comprising 102 women and 51 men. The mean patient age was 68.9years. The mean length of follow up was 15months. A statistically significant correlation was found between patient age, final height loss, height loss difference and kyphotic angle difference. Height loss difference and kyphotic angle difference were significantly correlated to type of fracture according to the AO classification system. The height loss difference was 18.1% in A1 type fractures, 27.1% in A2 type fractures, 24.2% in A3 type fractures and 25.7% in A4 type fractures. During a minimum 3-month follow up of conservative treatment for acute osteoporotic vertebral compression fractures, age and the AOSpine Thoracolumbar Spine Injury Classification System were predictive factors for progressive collapse.

Seven years follow-up for total lumbar facet joint replacement (TOPS) in the management of lumbar spinal stenosis and degenerative spondylolisthesis.

To evaluate the feasibility and clinical improvement of a total posterior arthroplasty system in the surgical management of lumbar degenerative spondylolisthesis and or spinal stenosis.

Surgical management of moderate adolescent idiopathic scoliosis with ApiFix®: a short peri- apical fixation followed by post-operative curve reduction with exercises.

Surgery in adolescent idiopathic scoliosis (AIS) is a major operative intervention where 10-12 vertebrae are instrumented and fused. A smaller motion preserving surgery would be more desirable for these otherwise healthy adolescents. The ApiFix® system is a novel less invasive short segment pedicle screw based instrumentation inserted around the apex of the main curve. The system has a ratchet mechanism that enables gradual postoperative device elongation and curve correction. The ratchet is activated by performing specific spinal exercises. The unique features of the device allow curve correction without fusion. The system which has a CE approval was employed in adolescents with main thoracic curves. More than a dozen of ApiFix surgeries have been performed so far. The preoperative Cobb angle was 45° ± 8, and 25° ± 8 at final follow up. The following is a report on three adolescent females aged 13-16 years with curves between 43°-53° and Risser sign of 1-4 who underwent surgery with ApiFix®. Two pedicle screws were inserted around the curve apex and the ratchet based device with polyaxial ring connectors was attached to the screws. No fusion attempt was made. Operative time was around one hour. Two weeks after surgery the patients were instructed to perform Schroth like daily exercises with the aim of rod elongation and gradual curve correction. Patients were followed between 6 months to 2 years. Curves were reduced and maintained between 22- 33°. Patients were pain free and were able to perform their spinal exercises. Postoperative gradual elongation of the device was observed. No screw loosening or rod breakage were observed. No adding on or curve progression was seen. Three factors may contribute to the ApiFix® success: polyaxial connections that prevent mechanical failure, gradual curve correction by spinal motion and spinal growth modulation. The ApiFix® system allows managing moderate AIS with a simple and minor surgical intervention. Recovery is rapid with negligible motion loss. It allows gradual and safe curve correction with high patient satisfaction. It may also serve as an internal brace for AIS.

The relation between location of cervical cord compression and the location of myelomalacia.

The purpose of this study was to examine the relationship between the location of the cervical cord compression and the increased signal intensity within the cervical cord on T2-weighted imaging (T2WI) in patients with cervical myelopathy and myelomalacia.

Incidental dural tears during lumbar spine surgery: a retrospective case study of 84 degenerative lumbar spine patients.

A retrospective case study.

The value of neuromonitoring in cervical spine surgery.

Radiographic predisposing factors for degenerative spondylolisthesis.

This study was a retrospective radiographic study involving analysis of computed tomography scans obtained for patients with degenerative spondylolisthesis of the L4-L5 segment and a control group. The purpose of the study was to identify radiological predisposing factors for degenerative spondylolisthesis of the L4-L5 segment. The authors reviewed all computed tomography scans (N=3370) performed at their institution between January 2005 and December 2008. Eighty-four patients with degenerative spondylolisthesis were identified and compared with a control group regarding facet joint orientation, the presence of sacralization of the L5 vertebra, the presence of major degenerative changes in the L5-S1 disk space, and the location of the intercrestal line. There was a statistically significant difference between the 2 groups regarding facet joint orientation, with more sagittal facet joints in the degenerative spondylolisthesis group (56° and 54° in the right and left facets, respectively, in the study group, and 46° and 42° in the right and left facets, respectively, in the control group) (P<.001). There was no statistically significant difference between the 2 groups regarding the presence of sacralization of the L5 vertebra, the presence of major degenerative changes in the L5-S1 disk space, and the location of the intercrestal line relative to the lumbar spine. There is an association between sagittal orientation of the facet joints at the L4-L5 segment and degenerative spondylolisthesis at the same level.

Assessing kyphosis with SpineScan: another attempt to reduce our dependence on radiography.

Kyphosis management is mainly conservative, with annual examinations to assess angular progression. This includes physical examination and usually long spine X-rays, notorious for ionizing radiation. Several nonradiological instruments have been devised for this, but none have become popular. SpineScan, a programmed digital inclinometer, has been proved effective for screening kyphoscoliosis.

Predictors of back pain in adolescent idiopathic scoliosis surgical candidates.

There are contradictory reports on the overall prevalence of back pain in the adolescent population compared with adolescent idiopathic scoliosis (AIS) patients. Most reports do not investigate pain in patients with AIS but try to identify in which subgroup of patients with AIS an underlying pathology should be excluded. The objective of this study was to find whether AIS in operative candidate patients is a painful condition and to try and find clinical and radiologic predisposing factors, which will help us to predict patients who are going to have pain.

Pediatric scoliosis surgery--is postoperative intensive care unit admission really necessary?

It is common practice for patients to be admitted to the intensive care unit following scoliosis surgery, because of the prolonged anesthesia, the need for efficient pain control and the known immediate postoperative complications. However, this may be unnecessary in many patients.

Remifentanil use in pediatric scoliosis surgery-an effective alternative to morphine (a retrospective study).

The unique properties of remifentanil make it ideal for pediatric use despite a lack of wide randomized clinical trials and fear of adverse events due to its high potency. We aimed to consolidate preliminary conclusions regarding the efficacy of remifentanil use in pediatric scoliosis surgery.

What is the best way to apply the Spurling test for cervical radiculopathy?

A diagnosis of cervical radiculopathy is based largely on clinical examination, including provocative testing. The most common maneuver was described in 1944 by Spurling and Scoville. Since then, several modifications of the original maneuver have been proposed to improve its value in the diagnosis of cervical radiculopathy.

Reversing the concept: correction of adolescent idiopathic scoliosis using the convex rod de-rotation maneuver.

To show the radiological results of adolescent idiopathic scoliosis (AIS) patients treated with posterior fusion using all-pedicle-screw construct with correction carried out using a convex rod reduction technique.

Treatment for Pott's disease with neurological complication.

Tuberculosis of the spine (Pott's disease) is the most common skeletal involvement in tuberculosis, and is often accompanied with neurological deficiency. Surgical treatment was previously the mainstay of therapy in cases of Pott's disease with neurological deficiency, but since clinical recovery was found in patients awaiting surgery, conservative management with antibiotic treatment as a first Line treatment has been advocated. This conservative approach may improve the patients' neurological status while avoiding the morbidity and mortality of surgical treatment.

Management of symptomatic vertebral hemangioma: follow-up of 6 patients.

Retrospective study.

Diabetes mellitus as a risk factor for the development of lumbar spinal stenosis.

Diabetes mellitus is a multi-organ disorder affecting many types of connective tissues, including bone and cartilage. Certain skeletal changes are more prevalent in diabetic patients than in non-diabetic individuals. A possible association of diabetes mellitus and lumbar spinal stenosis has been raised.

An unusual combination of a lumbar seat belt injury and hemorrhagic contusion of the lower thoracic cord in a 2-year-old child: a case report.

We describe a previously unreported combination of lumbar flexion-distraction ligamentous disruption and incomplete thoracic spinal cord injury in a 2-year-old boy. Magnetic resonance imaging of the thoracolumbar spine showed hemorrhagic cord contusion at the T11-T12 level. Plain radiographs showed mild kyphosis of the L3-L4 segment. Fluoroscopy showed pathological motion at L3-L4 in flexion indicating a ligamentous injury. The lumbar spine was surgically stabilized and at 1-year follow-up, a remarkable neurological recovery was noted. We believe that physicians managing children with multiple trauma injuries should be aware of this rare type of injury that might be underdiagnosed.

Hypothenar hammer syndrome: apropos of six cases and review of the literature.

Hypothenar hammer syndrome (HHS) is a rather rare condition and is a term used to describe an aneurysm or thrombosis of the ulnar artery. It is considered an occupational or recreational injury and is usually a result of a repetitive trauma to the hypothenar region where the unique anatomy of the Guyon canal allows arterial injury. HHS is one of the less common causes of symptomatic ischemia of the upper extremity. The aim of this article is to describe our experience with six patients. Presenting signs, symptoms, differential diagnoses, and literature review of this probably underdiagnosed syndrome are described. There are two pathologic entities: the aneurysmal type and the thrombotic type. Although most authors recommend watchful observation for the thrombotic type, reconstructive surgery is the treatment of choice for the aneurysmal type.

Lumbar stenosis and systemic diseases: is there any relevance?

A retrospective study of spinal stenosis patients admitted to Assaf Harofeh Medical Center Orthopedic Departments.

The use of dynamic CT surview for cervical spine clearance in comatose trauma patients: a pilot prospective study.

Bedside flexion and extension fluoroscopy was proposed for detecting occult ligamentous instability in comatose trauma patients. Nevertheless, a recent study showed that the C7-T1 motion segment is rarely visualised by this technique. We propose a new method for clearing the cervical spine in comatose patients.

Discitis and isthmic spondylolisthesis: a case report.

Spondylolysis and spondylolisthesis are common causes of low back pain in children and adolescents. Disc space infection is less common, but is another cause of severe back pain in this population. The combination of both processes in the same segment is rare. This case report is of a 13-year-old patient with isthmic lumbosacral spondylolisthesis and disc space infection at the same level. A patient who presented with severe low back pain and a radiological picture of isthmic slip with end plate irregularities and anterior bridging osteophyte was diagnosed with disc space infection at the slip level. He was managed with intravenous antibiotics for 6 weeks, followed by oral medication for an additional 2 weeks. At follow-up 28 weeks later, a spontaneous radiological fusion at the slip level was noted with complete relief of his symptoms. The patient was able to resume sports activities. In conclusion, isthmic spondylolisthesis and disc space height infection might coexist. Nonoperative treatment will usually result in spontaneous fusion and the complete relief of symptoms.

Risk factors affecting the immediate postoperative course in pediatric scoliosis surgery.

A retrospective analysis of pediatric records of idiopathic scoliosis (IS) and neuromuscular scoliosis (NMS) etiology, in a search for complications and their risk factors immediately following surgical repair.

Superior mesenteric artery syndrome after scoliosis repair surgery: a case study and reassessment of the syndrome's pathogenesis.

We carried out a retrospective analysis to investigate the prevalence of superior mesentery artery syndrome (SMAS) in children who underwent scoliosis surgical repair at our hospital between 1998 and 2006 and to reassess the syndrome's pathogenesis. Among 133 consecutive pediatric patients, two cases were identified, both 13-year-old girls with idiopathic scoliosis, undergoing surgery using third-generation instrumentation systems. Conservative management achieved resolution of the symptoms without recurrence. SMAS prevalence in our series was 1.6%. SMAS might occur after derotation and translation forces application, and even with nonextreme corrections. Low BMI and significant weight loss at presentation are not mandatory.

Diagnosis and treatment of spine metastases.

Metastatic disease of the spine occurs in as many as 70% of cancer patients. Patients may present with pain, neurologic deficit, or both. Treatment options include medical therapy, radiation, and surgery. The diversity of patients' conditions, tumors pathology, and the extent of disease complicate decision making and treatment. Treatment goals are palliative, aiming for pain control and maintenance of mobility. A multimodality therapy, results in better outcomes.

Treatment of lumbar spinal stenosis with a total posterior arthroplasty prosthesis: implant description, surgical technique, and a prospective report on 29 patients.

Total disc replacement is an alternative to lumbar fusion, but patients with spinal stenosis, spondylolisthesis, and facet arthropathy are often excluded from this procedure because increased adjacent-segment motion can exacerbate dorsal spondylotic changes. In such cases of degenerative spondylolisthesis with stenosis, decompression and fusion remain the gold standard of treatment. To avoid attendant loss of motion at the treated segment, the TOPS system is a novel total posterior arthroplasty prosthesis that allows for an alternative dynamic, multiaxial, three-column stabilization and motion preservation. The purpose of this study is to report preliminary surgical data and clinical outcomes in patients treated with the TOPS lumbar total posterior arthroplasty system.

Management of deep wound infection after posterior lumbar interbody fusion with cages.

To evaluate long-term treatment outcome of patients with infected posterior lumbar interbody fusion (PLIF) managed with surgical debridement and or prolonged antiobiotic treatment without removal of the interbody cages.

Intermediate screws in short segment pedicular fixation for thoracic and lumbar fractures: a biomechanical study.

To determine the effect of adding pedicle screws at the level of a burst fracture (intermediate screws) on the stiffness of a short segment pedicle fixation, an in vitro biomechanical study was carried out. Six fresh-frozen pig lumbar spine specimens were used. The flexibility of the intact specimens was examined in flexion, extension, lateral bending, and torsion. An unstable burst fracture model was created by the dropped-mass technique. The unstable spine specimens were instrumented with pedicle screws. The flexibility was tested again with and without intermediate screws. The addition of intermediate screws provided a smaller range of motion in flexion-extension (P<0.001), torsion (P<0.001), and lateral bending (P=0.014). The slopes of the load displacement curves increased in flexion (P<0.001), extension (P=0.003), lateral bending (P=0.003), and torsion (P=0.006), signifying a decrease in flexibility. The addition of intermediate screws at the level of a burst fracture significantly increases the stiffness of a short segment pedicular fixation.

Avoiding neurologic complications following ligation of the segmental vessels during anterior instrumentation of the thoracolumbar spine.

A retrospective evaluation of anterior instrumentation of the vertebral bodies in the thoracolumbar spine.