Preclinical Bench Testing on a Novel Posterior Dynamic Deformity Correction Device for Scoliosis.

STUDY DESIGN: Biomechanical test. OBJECTIVE: To summarize the preclinical tests performed to assess the durability of a novel fusionless dynamic device for the treatment of adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: The minimal invasive deformity correction (MID-C) system is a distractible posterior dynamic deformity correction device designed to reduce scoliosis for AIS patients, to maintain curve correction, and to preserve spinal motion. To overcome the challenges of wear and fatigue of this procedure, the system has two unique features: polyaxial joints at the rod-screw interface and a ceramic coating of the moving parts. METHODS: Five biomechanical tests were performed: Static compression to failure, fatigue loading per ASTM F 1717 with 5.5-mm screws for 10 million cycles (MC) at 5 Hz, wear assessment, wear test of the polyaxial joint under 100 N load for 10 MC, and wear particle implantation in rabbits. RESULTS: The system failed through buckling of the rod with loads over 3000 N (400% of human body weight). Dynamically, the system maintained 700 N for 10 MC with 5.5 mm screws. The maximum total steady-state wear rate was 0.074 mg/MC (0.03 per polyaxial joint and 0.014 mg/MC for the ratchet mechanism). Histologic evaluation of the particle injection sites indicated no difference in the local tissue response between the control and test articles. At 3 and 6 months postinjection, there were neither adverse local effects nor systemic effects observed. CONCLUSIONS: The unique design features of the MID-C system, based on polyaxial joints and ceramic coating, resulted in favorable static, fatigue, and wear resistance properties. Wear properties were superior to those published for artificial spinal discs. Long-term outcomes from clinical use will be required to correlate these bench tests to the in vivo reality of clinical use. LEVEL OF EVIDENCE: Level V.

In vivo macrophage recruitment by murine intervertebral disc cells.

SUMMARY: An in vivo murine experiment was conducted to measure the capacities of viable intervertebral disc cells to recruit inflammatory cells. The objective was to determine whether compounds secreted from viable cells induce inflammation or whether inflammation in disc herniation simply requires exposure to structural cell or matrix components. Three tissue preparations were inserted into the right lower peritoneal cavity of male mice: tissue with viable annulus fibrosus and nucleus pulposus cells, tissue with viable annulus fibrosus cells, or devitalized annulus fibrosus and nucleus pulposus tissue. Controls included sham-operated and nonoperated groups. Mice were killed 1, 2, or 7 days after surgery. Macrophage recruitment occurred after exposure to viable disc tissue but not after exposure to devitalized disc components; recruitment increased over time. Viable disc cells play a role in the etiology of inflammation in disc herniation.

Orthopaedic manifestations of familial dysautonomia. A review of one hundred and thirty-six patients.

BACKGROUND: Familial dysautonomia is a hereditary multisystemic disease primarily affecting people of Ashkenazi Jewish descent. Musculoskeletal problems are related to gait disorders, spinal deformities, foot deformities, fractures, and arthropathies. METHODS: The charts and radiographs of 136 patients who ranged in age from three months to forty-six years (mean, sixteen years) were reviewed. Sixty-four patients were available for follow-up examination. RESULTS: Spinal deformity was the most common orthopaedic problem and was diagnosed in seventy-eight patients starting at the age of four years, with a prevalence of 86 percent (forty-eight of fifty-six) by the age of fifteen years. Forty-one (53 percent) of the seventy-eight patients had scoliosis only, thirty-four (44 percent) had kyphoscoliosis, and three (4 percent) had kyphosis only. Bracing was accompanied by emotional, pulmonary, and skin problems, leading to a high rate of noncompliance and progression of the curve. Twenty-four patients had an operation at a mean age of thirteen years (range, five to eighteen years): twenty patients had posterior spinal arthrodesis, and four had combined anterior and posterior arthrodesis. Fifteen patients had a total of nineteen complications, of which seven were systemic and twelve were related to the spinal fixation. Eight patients had revision surgery. At the time of the surgery, scoliosis was corrected from a mean of 55 degrees to a mean of 35 degrees and kyphosis was corrected from a mean of 69 degrees to a mean of 61 degrees. After a mean duration of follow-up of sixty-five months, scoliosis measured 49 degrees (range, 18 to 62 degrees) and kyphosis measured 67 degrees (range, 30 to 115 degrees). Postoperative progression of the deformity was caused by failure of the instrumentation or progression in unfused segments. Walking was delayed in 72 percent (ninety-four) of the 130 patients who were of walking age. All sixty-four of the patients who were examined had an ataxic gait. Foot deformities were found in sixteen patients, six of whom were treated surgically. Two patients had Charcot joints. Fifty-five patients sustained at least one fracture before skeletal maturity, with a mean of 1.5 fractures per patient. All but one of the fractures was treated nonoperatively, and fracture-healing was often accompanied by profuse callus formation. CONCLUSIONS: Spinal deformity is common in patients with familial dysautonomia. Bracing is of questionable benefit, and surgical intervention should be considered once curve progression is well documented. Arthrodesis should be extended as far proximally as possible to prevent junctional kyphosis. Swelling and warmth in a limb should raise suspicion of an undiagnosed fracture.

Progression of lumbosacral isthmic spondylolisthesis in adults.

STUDY DESIGN: A retrospective clinical and radiographic review of adult patients with progressive isthmic lumbosacral spondylolisthesis. OBJECTIVES: To describe the clinical presentation of adult-onset progression of isthmic spondylolisthesis and to analyze its causes. SUMMARY OF BACKGROUND DATA: Until recently, progression of lumbosacral spondylolisthesis in adults was rarely reported. On the contrary, although slip progression before skeletal maturity has been widely recorded, its occurrence in adults has been doubted. Only sporadic case reports of adult slip progression and only brief notes on the subject in clinical studies describing other aspects of spondylolisthesis have been published. METHODS: Patients with isthmic lumbosacral spondylolisthesis who had serial radiographs of the lumbar spine on which slip progression during adult life was noted were evaluated. The amount of vertebral slip was calculated in millimeters from decubitus lateral spinal radiographs. The calculation was expressed as the percentage of slipped vertebral body length. RESULTS: From 1989 to 1995, 18 patients (9 women and 9 men), ages 32 to 55 years, with documented adult isthmic slip progression were identified at the Spinal Surgery Unit of the Hadassah University Hospital. All patients reported incapacitating low back pain, accompanied in most by significant sciatica. Documented slip progression ranged from 9% to 30% (average, 14.6%), and occurred during a period of 2 to 20 years (average duration, 6.8 years). Slip progression started after the third decade of life and coincided with marked disc degeneration at the olisthetic level. Slip progression associated with disc degeneration (i.e., intervertebral space narrowing and the formation of spondylophytes and vacuum phenomenon) brought about severe clinical symptomatology related to segmental instability and spinal stenosis. Of the 18 patients in this study, 14 were treated with surgery. All these patients except 1 underwent decompression, pedicle screw fixation, and bilateral lateral fusion. One patient underwent posterolateral fusion without instrumentation. Immediate postoperative complications were observed in three patients, including two superficial wound infections and one transient foot drop. Solid fusion was obtained in 11 of the 14 patients who underwent surgery. CONCLUSIONS: The concurrent occurrence of disc degeneration at the slip level and adult slip progression explains how an asymptomatic developmental lesion, present for at least two to three decades, may become symptomatic.

Pulse oximetry plethysmographic waveform during changes in blood volume.

Systolic pressure variation (SPV) and its dDown component have been shown to be sensitive factors in estimating intravascular volume in patients undergoing mechanical ventilation. In this study, ventilation-induced changes in pulse oximeter plethysmographic waveform were evaluated after removal and after reinfusion of 10% estimated blood volume. The plethysmographic waveform variation (SPVplet) was measured as the difference between maximal and minimal peaks of waveform during the ventilatory cycle, and expressed as a percentage of the signal amplitude during apnoea. dUp(plet) and dDown(plet) were measured as the distance between the apnoeic plateau and the maximal or minimal plethysmographic systolic waveform, respectively. Intravascular volume was changed by removal of 10% of estimated blood volume and followed by equal volume replacement with Haemaccel. A 10% decrease in blood volume increased SPVplet from mean 17.0 (SD 11.8)% to 31.6 (28.0)% (P = 0.005) and dDown(plet) from 8.7 (5.1)% to 20.5 (12.9)% (P = 0.0005) compared with baseline. Changes in plethysmographic waveform correlated with changes in arterial SPV and dDown (r = 0.85; P = 0.0009). In the absence of invasive arterial pressure monitoring, ventilation-induced waveform variability of the plethysmographic signal measured from pulse oximetry is a useful tool in the detection of mild hypovolaemia.

Sequential or simultaneous, same-day anterior decompression and posterior stabilization in the management of vertebral osteomyelitis of the lumbar spine.

STUDY DESIGN: A retrospective clinical study of patients with vertebral osteomyelitis of the lumbar spine necessitating surgical treatment. All patients underwent sequential (same-day) or simultaneous anterior decompression and posterior stabilization of the involved vertebrae. OBJECTIVE: To evaluate the efficacy and clinical out-come of sequential or simultaneous anterior and posterior surgical approaches in the management of vertebral osteomyelitis of the lumbar spine. SUMMARY OF BACKGROUND DATA: Anterior approach alone and staged anterior decompression and posterior stabilization have been advocated as the surgical treatment methods of choice for patients with vertebral osteomyelitis of the lumbar spine. The drawbacks of the latter management plan are the necessity to use external support or the delayed patient mobilization and the need for additional anesthesia and surgical trauma. Sequential (same-day) anterior and posterior approaches are used regularly in the surgical management of scoliosis and other spinal deformities. It would appear advantageous to also use the same strategy (i.e., combined same-day double approaches) in the management of vertebral osteomyelitis of the lumbar spine. METHODS: Ten consecutive patients who had a diagnosis of vertebral osteomyelitis of the lumbar spine underwent combined (same-day) anterior and posterior approaches either in a sequential or simultaneous manner. Indications for surgery included neurologic deficit, abscess formation, instability with localized kyphosis formation, and failure of nonoperative treatment. Patients were evaluated clinically and radiographically after surgery. RESULTS: All 10 patients had uneventful surgery. Only one patient required a second surgical procedure because of expulsion of the anterior bone graft and pull-out of instrumentation. All patients were mobilized within the 2 days immediately after surgery. At the mean follow-up examination 30 months after surgery, all patients had regained their motor function and prior ambulatory status. CONCLUSIONS: Patients with lumbar osteomyelitis necessitating surgery can undergo combined, same-day surgery either in a sequential or simultaneous manner. This is a safe and efficient way to control the infection and stabilize the affected segments, allowing for early mobilization of these sick elderly patients.

Compression of the esophagus by the spine and the aorta in untreated scoliosis.

An adult patient with severe scoliosis secondary to familial dysautonomia developed dysphagia and recurrent aspirations. Various imaging studies showed a mechanical obstruction of the esophagus due to compression between the spine and the aorta. The patient underwent a gastrostomy and fundoplication, with a significant decrease in symptoms. The case demonstrates one of the possible long-term consequences of untreated scoliosis.

An algorithm for selection of instrumentation levels in scoliosis.

Appropriate levels for instrumentation and fusion in scoliosis have been a matter of debate among surgeons since the introduction of operative management of this deformity. We set out to examine the hypothesis that the amount of correction achieved in all planes during surgical instrumentation of a curve should be less than, or comparable to, the degree of correction attainable at any non-instrumented adjacent curve. An algorithm was designed to facilitate preoperative planning and intraoperative performance of spinal fusion procedures in the management of scoliosis. To test the validity of the hypothesis and the proposed algorithm, measurements were taken from the preoperative radiographs of 200 patients. The dimensions of the curves were obtained from an initial set of four X-ray films: (1) standing anteroposterior film of the whole spine, (2) standing lateral film of the whole spine, (3) two properly performed side-bending films including each curve of the spine. With this data, a plan was designed using the algorithm. The results of this plan were compared with the actual results of the surgery, which were revealed only at this stage. All patients in whom actual instrumentation levels fell within those predicted by the proposed algorithm had no imbalance at follow-up. All patients whose actual instrumentation levels were short of those recommended by the algorithm showed obvious imbalance on final postoperative standing radiograph.

Thoracic scoliosis and restricted neck motion: a new syndrome? A report of six cases.

The cases of six adolescent males with a mild thoracic scoliosis of unknown etiology and a marked limitation of neck flexion are reported. All six complained of mild thoracic spine pain and were 13-17 years old at the onset of their symptoms. In addition to the thoracic scoliosis, all were found to have a marked limitation of neck flexion. They were unable to touch their chest wall with their chin. None had a positive family history of scoliosis. Radiological examination revealed a thoracic scoliosis of 10 degrees-40 degrees, no abnormalities were detected on cervical spine plain radiographs. Extensive investigations, including MRI of the entire spine, failed to disclose the cause of the spinal deformity or the mechanism causing the limitation of neck motion. Apart from the limited cervical flexion and mild pain, this condition was found to be benign and the spine deformity to be mild or moderate in nature and with limited progression. Review of the literature failed to identify similar cases.

Murine nucleus pulposus-derived cells secrete interleukins-1-beta, -6, and -10 and granulocyte-macrophage colony-stimulating factor in cell culture.

STUDY DESIGN: Cultures established from murine disc-derived cells were stimulated by lipopolysaccharide. The cells' capacity to secrete proinflammatory cytokines and interleukin-10 with and without lipopolysaccharide stimulation was determined using enzyme-linked immunosorbent assays. OBJECTIVES: To determine the capacity of disc-derived cells to secrete proinflammatory cytokines, and the effect of lipopolysaccharide stimulation on such secretion. SUMMARY OF BACKGROUND DATA: The pathophysiology of compressive radiculopathy is unclear. Inflammation is a possible explanation. Proinflammatory cytokine secretion was demonstrated in herniated nucleus pulposus. It is unknown whether these cytokines are secreted from disc-derived cells or from infiltrating inflammatory cells in the herniated nucleus pulposus. METHODS: Discs were microsurgically harvested from inbred mice and cut to allow the nucleus pulposus to establish cell culture. A study group was exposed to lipopolysaccharide stimulation. Media were harvested from the study and control groups 24 hours later. Secretion of interleukins-1-, -6, and -10, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-alpha were determined using enzyme-linked immunosorbent assays. RESULTS: Basal secretion of interleukins-6 and -10, but no basal secretion of interleukin-1-, granulocyte-macrophage colony-stimulating factor, or tumor necrosis factor-alpha was detected. Secretion of interleukin-1- rose from zero to 27.69 pg/10(5) cells, and granulocyte-macrophage colony-stimulating factor secretion rose from zero to 9.77 pg/10(5) cells after lipopolysaccharide stimulation. A 75-fold increase in interleukin-6 secretion and a 150-fold increase in interleukin-10 secretion were detected after stimulation with lipopolysaccharide. No tumor necrosis factor-alpha secretion was detectable. All result had high statistical significance (all P < 0.001). CONCLUSIONS: Cultured murine disc-derived cells have the capacity to secrete proinflammatory cytokines and interleukin-10 in the absence of inflammatory cells. This finding supports the hypothesis that disc-derived cells are capable of initiating or amplifying an inflammatory process.

Foraminal herniation of a lumbar disc mimicking neurinoma on CT and MR imaging.

A case of a large L3-L4 intervertebral disc herniation causing a widening of the intervertebral foramen is reported. There was a soft-tissue mas within the spinal canal and intervertebral foramen. The soft-tissue mass within the spinal canal and intervertebral foramen showed marked enhancement on magnetic resonance scans after injection of a paramagnetic contrast agent (Gd-DTPA). The combination of lesion configuration and paramagnetic contrast enhancement mimicked a spinal neurinoma. There exists a degree of overlap between the imaging of herniated discs and spinal neurinomas. When this overlap involves several aspects, such as anatomic configuration, mass enhancement, and secondary foraminal dilatation, the differential diagnosis between a herniated disc and a neurinoma may be problematic.

Eosinophilic granuloma of the spine.

Twenty patients treated for eosinophilic granuloma of the spine were studied. Only 40% demonstrated the classical radiographic picture of vertebra plana. In 60% a lytic lesion of the vertebral body or the posterior elements was found. Seven patients underwent surgery; the indications were neurological involvement or failure of the biopsy to disclose the diagnosis. At an average follow-up period of 7 years, 17 patients are well and alive with no residual spinal pain, neurological compromise, recurrent disease, or extraskeletal involvement. Vertebral body collapse underwent some regeneration but did not regain full body height. In several patients this resulted in a local deformity. In patients with unifocal spinal eosinophilic granuloma, watchful observation with no treatment other than spinal support is warranted. In patients with neural involvement or multifocal lesions, a more active treatment, including surgery, may be indicated.

Fracture of the occipital condyles and associated craniocervical ligament injury: incidence, CT imaging and implications.

Thin section contiguous axial computer tomography (CT) was used to demonstrate fractures of the occipital condyle and craniocervical ligament injury. During a 12-month period, 55 consecutive patients who had sustained high energy blunt trauma to the head or upper cervical region were examined (38 male and 17 female, age range 3-80 years, median 24 years). If occipital condyle fracture was suspected clinically, CT was performed from C2 to the foramen magnum with two dimensional sagittal, coronal, and curvilinear reconstructions and employing bone and soft tissue windows. Occipital condyle fractures were classified according to Anderson and Montesano types 1, 2 or 3. Injury to the internal craniocervical ligaments was described. Nine of 55 patients had occipital condyle fractures (16.4%). Injury of the alar ligaments was demonstrated in four and tectorial membrane injury in two patients. Three of the nine patients had associated fractures of cervical vertebrae. Five of nine patients had a normal Glasgow coma scale on admission (55%) and in two patients the occupital condyle fracture was the only significant injury. Plain cervical radiographs were non-diagnostic. Two patients had significant pain and limited motion of the craniocervicum several months following injury. In conclusion, CT should be performed where there is a high clinical suspicion of occipital condyle fracture, that is based mainly on the mechanism of injury.

Aspects of spinal deformity in familial dysautonomia (Riley-Day syndrome).

Familial dysautonomia (FD) is a rare autosomal recessive disease occurring in Jews of Ashkenazi descent, with only some 500 recognized cases. The causative gene was identified on chromosome 9. FD is of considerable orthopedic interest, because of the prevalence of skeletal deformity. About 90% of surviving dysautonomic children will develop a spinal curvature, commonly a scoliosis. The scoliotic curve is usually kyphotic rather than lordotic, and appears during the first decade of life. Fifty-one of the 90 reported cases of familial dysautonomia in Israel involved patients who were seen at the scoliosis clinic for assessment and treatment of their spinal deformities. Most of the patients presented with a scoliotic deformity associated in 37 cases with an increased thoracic kyphosis. In our series orthotic treatment and physiotherapy were found to be minimally successful at best. Surgical treatment of the spine was performed in 13 of 51 patients in this series. A retrospective review of these patients' charts and radiographs was carried out. Six years of follow-up are reported. The primary indication for surgery was progression of the spinal curve. Only posterior spinal fusions were performed. Anterior transthoracic procedures were avoided in spite of the significance of the kyphotic deformity, because of the frequency of pulmonary complications. Harrington distraction and compression instrumentation was used. Three-millimeter compression rods were used in a distraction mode in thin, young children. "Harri-Luque" segmental sublaminar wiring technique and Wisconsin spinous process segmental wiring was used in some. In all cases, the spine fusion was supplemented by bank bone only, to avoid the additional trauma of graft removal. We believe that surgical intervention is advantageous, if done early in the evolution of spinal deformity. Greater technical difficulties and a higher complication rate were encountered in this series relative to the problems usually seen after spinal deformity surgery in children; this is all the more important in a disease in which general anesthesia is an additional major complicating factor. It is hoped that the improved physical condition now seen after early gastrostomy and fundoplication will aid in reducing this high complication rate. Only a small degree (about 25%) of correction was achieved in the majority of patients. Some of this apparent rigidity derived from the inability to apply sufficient instrumental corrective force because of the friable osteoporotic bone. After surgery, there was a marked decrease in the frequency of pneumonia and an improvement in the degree of ataxia, for reasons not understood, which led to an obvious improvement in the quality of life.

Spinal manipulation results in immediate H-reflex changes in patients with unilateral disc herniation.

The aim of this clinical investigation was to determine whether the abnormal H-reflex complex present in patients with S1 nerve root compression due to lumbosacral disc herniation is improved by single-session lumbar manipulation. Twenty-four patients with unilateral disc herniation at the L5-S1 level underwent spinal H-reflex electro-physiological evaluation. This was carried out before and after single-session lumbar manipulation in the side-lying position. Eligibility criteria for inclusion in the study were: predominant sciatica, no motor or sphincteric involvement, unilateral disc herniation at the L5-S1 level on CT or MR imaging, age between 20 and 50 years. H-reflex responses were recorded bilaterally from the gastrosoleous muscle following stimulation of tibial sensory fibers in the popliteal fossa. H-reflex amplitude in millivolts (HR-A) and H-reflex latency in milliseconds (HR-L) were measured from the spinal reflex response. Pre- and post-manipulation measurements were compared between the affected side and the healthy side. Statistical evaluation was performed by the Wilcoxon matched-pairs test (SPSS). Thirteen patients displayed abnormal H-reflex parameters prior to lumbar manipulation, indicating an S1 nerve root lesion. The mean amplitude was found to be significantly lower on the side of disc herniation than on the normal, healthy side (P = 0.0037). Following manipulation, the abnormal HR-A increased significantly on the affected side while the normal HR-A on the healthy side remained unchanged (P = 0.0045). There was a significant difference between latencies on the affected side and those on the healthy side (P = 0.003). Following manipulation there was a trend toward decreased HR-L. However, this trend did not reach statistical significance (P = 0.3877). Eight patients displayed no H-reflex abnormalities before or after manipulation. Their respective HR-A and HR-L values did not change significantly following manipulation. Three additional patients were excluded due to technical difficulties in achieving manipulation or measuring spinal reflex. These observations may lend physiological support for the clinical effects of manipulative therapy in patients with degenerative disc disease.

Occipital condyle fracture and ligament injury: imaging by CT.

The true incidence of fracture of the occipital condyles is unknown. It may be associated with instability at the craniocervical joint. CT is the modality of choice for the demonstration of these fractures, but its use for imaging of the associated ligament injury has not been reported. In order to demonstrate normal anatomy, occipital condyle fracture and ligament injury, and to estimate the incidence of this lesion, 21 children and young adults with high-energy blunt craniocervical injury were examined prospectively. Thin-slice, axial, contiguous, CT was performed from the base of C2 to above the foramen magnum. Bone and soft tissue windows and coronal, sagittal, and curvilinear 2D reconstructions were performed. Five occipital condyle fractures were identified in four patients (19 %), with demonstration of alar ligament injury in two cases and local hematoma in one. In four, artifacts or rotation precluded assessment of ligaments. In all remaining cases normal bone and ligament anatomy was demonstrated. Fracture of the occipital condyles following craniocervical injury is not uncommon in children and young adults. Normal bone and ligament anatomy and pathology can be safely and clearly demonstrated in seriously injured patients and others using this CT technique. Increased awareness of this entity and a low threshold for performing CT should avoid the potentially serious consequences of a missed diagnosis.

The relationship between degenerative changes and osteoporosis in the lumbar spine.

Degenerative changes in the spine, specifically disc degeneration and facet arthrosis, and osteoporosis are conditions that primarily affect the elderly and may significantly impact the quality of life. The relationship between osteoporosis and degenerative changes in the hip joint has been studied, but their correlation in the spine is not entirely clear. Two hundred ninety-four subjects older than 50 years of age were retrospectively studied for the existence of lumbar spinal degeneration and osteoporosis through radiologic examination for 3 clinical manifestations: (1) disc degeneration, (2) facet joint arthrosis, and (3) lumbar osteoporosis. Peripheral osteoporosis in the distal radius of the nondominant hand was measured using a single-photon bone absorptiometer. Results indicated that subjects with severe osteoporosis in the distal radius also had severe degenerative changes in the discs and the facets; those with mild osteoporosis in the distal radius showed a tendency to have a lesser degree of degenerative changes than the subjects without osteoporosis.