Yigal Mirovsky

Accuracy and safety of thoracic pedicle screw placement in spinal deformities.

Objectives: To determine the safety of pedicle screw fixation in thoracic spine deformity correction. Methods: One hundred twelve pedicle screws were surgically placed in 25 patients with degenerative, posttraumatic, and Scheuermann kyphosis and idiopathic and neuromuscular scoliosis. Screw position was evaluated using intraoperative and postoperative radiographs and thin-slice computed tomography. Results: Of the total 112 thoracic pedicle screws that were inserted, 98 screws (87.5%) were fully contained within the cortical boundaries of the pedicle. When comparing proximal screws (T1-T8) with distal screws (T9-T12) and convex placed screws with concave ones, a statistically significant difference in screw placement was evident (P < 0.05). More misplaced screws were seen proximally and on the concave side. Of the 14 malpositioned screws, 2 (1.8%) demonstrated aortic abutment. There were no neurologic deficits, vascular injuries, or mechanical failures recorded. Conclusions: Placement of thoracic pedicle screws is both feasible and safe.

Injuries to the lateral femoral cutaneous nerve during spine surgery.

STUDY DESIGN A prospective study to locate patients with injured lateral femoral cutaneous nerve after elective spine surgery. OBJECTIVES To assess the prevalence of injury of the lateral femoral cutaneous nerve and to identify the cause of injury according to the position of the patients at surgery and the surgical approach. SUMMARY OF BACKGROUND DATA Injuries to the lateral femoral cutaneous nerve, also known as meralgia paresthetica, may cause pain and therefore result in restriction of activity. Compression of the nerve by disc hernia, retroperitoneal tumors, and external pressure around the anterior superior iliac spine are among the more common causes. METHODS One hundred five patients admitted for elective spine procedures were grouped according to position on the operating table and surgical approach. All patients were examined before and after surgery for signs of injury to the lateral femoral cutaneous nerve, and those found injured were followed up for 1 year after surgery. RESULTS Injury to the lateral femoral cutaneous nerve was found in 21 (20%) patients. In 6 of them, all of whom underwent surgery on the Hall-Relton frame, the injury was bilateral. In 7 patients the injury was not associated with discomfort. In addition to injury by external pressure at the anterior superior iliac spine from the Hall-Relton frame, the nerve was also injured at the retroperitoneum by hematoma or traction and at the anterior iliac crest when bone was harvested. In 89% of the patients, the nerve completely recovered within 3 months of surgery. Two patients still had pain 1 year after surgery and hypoesthesia of the anterolateral thigh. CONCLUSION Injuries to the lateral femoral cutaneous nerve during spine surgery are frequent, and patients should be informed of the possible risk. It usually has a benign course, but some preventive steps should be taken: keep posterior to the anterior superior iliac spine and minimize retraction when harvesting a bone graft, pad the posts of the Hall-Relton frame over the anterior superior iliac crest, and avoid traction on the psoas muscle during the retroperitoneal dissection.

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.

Changes in proteoglycans of intervertebral disc in diabetic patients. A possible cause of increased back pain.

Study Design. Characterization of the analytic profile of proteoglycans in the intervertebral discs at L4‐L5 of nondiabetic (n = 5) and diabetic (n = 5) age‐matched subjects. The discs used were discarded material from operations. Objectives. To clarify the reason for the higher risk of disc prolapse in diabetic patients. Summary of Background Data. The pathogenesis of diabetes results from a combination of neurologic dysfunctions and a yet undefined metabolic failure, which leads to an abnormal proteoglycan profile. Methods. The following methods were used to determine the proteoglycan profile: the measurement of 35S‐sulfate uptake per gram wet tissue into sulfated glycosaminoglycan using fresh tissue explants; extraction of proteoglycans by 4 M guanidinium chloride containing protease inhibitors, with further purification by ultracentrifugation on cesium chloride buoyant density gradient under dissociative conditions; total uronic acid and protein contents in the various gradient fractions; assessing the length of sugar side chains of isolated 35 Sulfate‐glycosaminoglycan molecules by separation of the glycosaminoglycan molecules on a Sepharose 6B‐CL column; and paper chromatography of the final digest products of glycosaminoglycan molecules obtained by chondroitinase ABC, a glycosaminoglycan‐degrading enzyme. Results. The findings show that discs from normal nondiabetic subjects have 15 times the rate of 35Sulfate incorporation into glycosaminoglycan molecules than do discs of diabetic patients. The proteoglycans of diabetic patients are banded at a lower buoyant density, indicating a lowered glycosylation rate and a lower number of sugar side chains per core protein. In discs of diabetic patients, there is a slight increase in the chain length of chondroitin sulfate. Further analysis of the glycosaminoglycan chains showed a decreased amount of keratan sulfate, compared with that in nondiabetic subjects. However, the total uronic acid content of the disc tissues and the ratio of uronic acid to protein of each fraction were unchanged in diabetic patients versus that in control subjects. Conclusions. Discs in patients with diabetes have proteoglycans with lower buoyant density and substantially undersulfated glycosaminoglycan, which with the specific neurologic damage in these patients, might lead to increased susceptibility to disc prolapse.

Intradiscal cement leak following percutaneous vertebroplasty.

Study Design. A retrospective study to detect patients with cement leakage into the disc space following vertebroplasty. Objective. To determine the frequency, causes, and clinical significance of cement leakage into the disc space. Summary of Background Data. Much has been written about cement leakage into the epidural space following vertebroplasty but only little about intradiscal leakage. Methods. A total of 66 patients with 1 cemented osteoporotic, fractured vertebra between T5 and L5 were followed for at least 2 years. Two of the senior authors (Y.M. and A.P.) evaluated independently cement leakage into the disc space, possible causes were investigated, and the clinical results were evaluated according to patient self-assessment. Results. Detected in 27 patients, cement leakage into the disc space did not negatively affect patient satisfaction with the procedure. In 7 of these patients, leakage occurred through an intravertebral vacuum cleft and, in 8, through a perforation of the endplate created by the needle tip. In only 2 patients was cement found to cross the height of the vertebral body and leak into the contralateral disc. Conclusions. Apart from iatrogenic endplate perforation, cement extravasation into the disc space was always found to occur through the fractured endplate or a vacuum cleft. Placing the needle tip far from the fractured endplate and using more solid cement appear to decrease the risk of leakage.

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.

Comparison between the outer table and intracortical methods of obtaining autogenous bone graft from the iliac crest.

STUDY DESIGN A prospective study in two groups of patients selected randomly. OBJECTIVES To determine whether keeping the outer and inner cortices of the ilium intact, while obtaining bone graft, would result in reduced postoperative bleeding and less postoperative pain. SUMMARY OF BACKGROUND DATA Donor site complications after harvesting bone from the iliac crest are frequent. They comprise pain and bleeding related to the large bone exposed, injuries to the cluneal nerve, and sacroiliac instability. METHOD Sixty patients who were admitted for elective fusion of lumbar segments were included in the study. In half of them, the iliac bone graft was taken in the outer Table method (group A), which included the outer cortex and the cancellous bone beneath, and in the remaining 30 patients only the cancellous bone from between the cortices was collected (group B). The amount of bone harvested, and the time taken to obtain it, were measured, as was the blood volume in the drains. At fixed intervals after surgery and up to 2 years thereafter, the patients were asked to grade the severity of pain in their back and at the donor site. RESULTS Two years after surgery, 22% of the patients in group A and 17% of the patients in group B reported to have significant pain at the donor site. This difference was not found to be statistically significant, nor was the postoperative bleeding. The average amount of bone harvested in group A was 36 grams compared with 25.7 grams in group B, taking 14 minutes and 20.3 minutes, respectively, to harvest it. These differences were found to be statistically significant. CONCLUSIONS Preserving the iliac cortices, while obtaining bone graft, does not reduce the postoperative bleeding or the severity of pain at the donor site. In the intraosseous method, less bone is harvested and longer duration of surgery is required, compared with that of the outer Table method.

Safety and Efficacy of Dietary Agmatine Sulfate in Lumbar Disc‐associated Radiculopathy. An Open‐label, Dose‐escalating Study Followed by a Randomized, Double‐blind, Placebo‐controlled Trial

Objective. Agmatine, decarboxylated arginine, was shown in preclinical studies to exert efficacious neuroprotection by interacting with multiple molecular targets. This study was designed to ascertain safety and efficacy of dietary agmatine sulfate in herniated lumbar disc-associated radiculopathy. Study Design. First, an open-label dose escalation study was performed to assess the safety and side-effects of agmatine sulfate. In the follow-up study, participants diagnosed with herniated lumbar disc-associated radiculopathy were randomly assigned to receive either placebo or agmatine sulfate in a double-blind fashion. Methods. Participants in the first study were recruited consecutively into four cohorts who took the following escalating regimens: 1.335 g/day agmatine sulfate for 10 days, 2.670 g/day for 10 days, 3.560 g/day for 10 days, and 3.560 g/day for 21 days. Participants in the follow-up study were assigned to receive either placebo or agmatine sulfate, 2.670 g/day for 14 days. Primary outcome measures were pain using the visual analog scale, the McGill pain questionnaire and the Oswestry disability index, sensorimotor deficits, and health-related quality of life using the 36-item short form (SF-36) questionnaire. Secondary outcomes included other treatment options, and safety and tolerability assessment. Results. Safety parameters were within normal values in all participants of the first study. Three participants in the highest dose cohort had mild-to-moderate diarrhea and mild nausea during treatment, which disappeared upon treatment cessation. No other events were observed. In the follow-up study, 51 participants were randomly enrolled in the agmatine group and 48 in the placebo. Continuous improvement of symptoms occurred in both groups, but was more pronounced in the agmatine (analyzed n = 31) as compared with the placebo group (n = 30). Expressed as percent of baseline values, significantly enhanced improvement in average pain measures and in quality of life scores occurred after treatment in the agmatine group (26.7% and 70.8%, respectively) as compared with placebo (6.0% [P </= 0.05] and 20.0% [P </= 0.05], respectively). No treatment-related adverse events were noted. Conclusions. Dietary agmatine sulfate is safe and efficacious treatment for alleviating pain and improving quality of life in lumbar disc-associated radiculopathy. Study Registration. ClinicalTrials.gov Protocol Registration System Identifier: NCT00405041.

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

Study Design. 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. Objective. To evaluate the influence of pre- and intraoperative parameters on the postoperative course and lay the cornerstone for a course-prediction model. Summary of Background Data. Only a few studies have addressed the immediate postoperative complications of pediatric scoliosis surgery. Methods. Our study included all children who underwent spinal fusion for scoliosis in our hospital between 1998 and 2006. The following data were collected: curve etiology, Cobb angle, number of fused vertebrae, fusion approach, and the addition of thoracoplasty. We evaluated the influence of this data on the rate of delayed extubations, length of intensive care unit (ICU) hospitalization, and the presence of major and minor immediate postoperative complications. Results. The study included 126 children (95 IS and 31 NMS). Delayed extubations were recorded in 17 children (3% of IS vs. 45% of NMS). The most common major and minor complications were pulmonary and hematological-biochemical, respectively. Overall pulmonary complications (major and minor) were recorded in 38 children. Major complications (of any category) were recorded in 19 children. Average length of ICU hospitalization was 3.8 days. The rate of complications in the NMS group was significantly higher than in the idiopathic group. Posterior fusions were associated with a significantly lower rate of pulmonary complications and shorter ICU hospitalizations, in comparison to anterior and combined fusions. Cobb angle, number of fused vertebrae, and the addition of thoracoplasty did not correlate with any postoperative parameters. Conclusion. While NMS etiology, anterior and combined fusions correlated with a worse course, the Cobb angle, number of fused vertebrae, and the addition of thoracoplasty did not. Optimization of postoperative care should be carried out accordingly. Scoliosis surgery is safe even in extreme curves and long fusions. Thoracoplasty can be added whenever indicated, in order to improve the overall outcome.

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

Objectives 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. Methods Between 1996 and 1999, 8 out of 111 patients who underwent PLIF were diagnosed with deep wound infection (7.2%). All infected patients were clinically followed for at least 2 years after completion of the antibiotic treatment. Longer follow-up of at least 6 years duration was performed by a telephone interview. Results Six patients were managed with surgical debridement, wound irrigation, and primary closure of the wound. None of the patients required removal of the instrumentation. In 2 patients, the PLIF cages were repositioned in the face of infection. All 8 patients received 4 to 6 weeks of intravenous antibiotic therapy followed by another 6 to 9 weeks of oral antibiotic administration. At 2-year follow-up, no clinical or laboratory signs of recurrent infection were evident. Four of the 8 patients reported improved clinical status compared with their prefusion status. At 6-year follow-up, 3 patients had minimal disability according to the Oswestry Disability Index and 2 patients had moderate disability with residual leg pain. Conclusions In cases of postoperative deep wound infection after PLIF with cages, removal of the interbody implants is not necessary. Treatment is composed of prolonged antibiotic therapy guided by antimicrobial susceptibility of the isolated bacteria and supplemented with extensive surgical debridement if needed.