Nam Hyun Kim

Unilateral Versus Bilateral Pedicle Screw Fixation in Lumbar Spinal Fusion

STUDY DESIGN A prospective study of 87 patients who underwent unilateral or bilateral pedicle screw fixation. OBJECTIVES To determine whether unilateral pedicle screw fixation is comparable with bilateral fixation in one- or two-segment lumbar spinal fusion. SUMMARY OF BACKGROUND DATA Clinical results for unilateral variable screw placement instrumentation in isolated L4-L5 fusion have been reported to be as good as those for bilateral instrumentation. However, unilateral instrumentation may not be recommended for multilevel fusion. METHODS Eighty-seven patients were assigned to either unilateral (n = 47) or bilateral (n = 40) pedicle screw instrumentation groups. Two kinds of pedicle screw system (Moss Miami, DePuy, Warsaw, IN, and Steffee VSP, AcroMed, Cleveland, OH) were used. Operating time, blood loss, duration of hospital stay, clinical outcomes, fusion rates, complication rates, and medical expenses were studied and tested with independent sample t test and chi2 test. RESULTS There were no significant differences between the two groups in blood loss, clinically satisfactory results, fusion rate, and complication rate. There were significant differences in duration of operating time, duration of hospital stay, and medical expenses. The number of fusion segments or kinds of instrumentation did not affect the fusion rate or clinical outcomes. CONCLUSIONS Unilateral pedicle screw fixation was as effective as bilateral pedicle screw fixation in lumbar spinal fusion independent of the number of fusion segments (one or two segments) or pedicle screw systems. Based on the results of this study, unilateral fixation could be used in two-segment lumbar spinal fusion.

Anterior interbody fusion versus posterolateral fusion with transpedicular fixation for isthmic spondylolisthesis in adults. A comparison of clinical results.

STUDY DESIGN Clinical and radiographic results were assessed in adult patients who had undergone operation for isthmic spondylolisthesis. OBJECTIVES To compare the results between anterior interbody fusion and posterolateral fusion with those of transpedicular fixation for the treatment of isthmic spondylolisthesis in adults. BACKGROUND DATA Successful clinical results after fusion can be expected in adolescents, but the adult type differs in that stability through fusion alone fails to ensure satisfactory outcomes. The role of decompression in the surgical treatment of adult isthmic spondylolisthesis remains controversial. Anterior interbody fusion has an indirect effect of nerve root decompression through widening of the intervertebral space, whereas posterolateral fusion with transpedicular fixation provides direct decompression. METHODS The clinical data of 40 adult patients who had undergone operations for isthmic spondylolithesis from June 1977 through June 1994 were reviewed. Anterior interbody fusion was performed in 20 patients (Group I) and posterolateral fusion with transpedicular fixation in 20 patients (Group II). The mean age of Group I was 44.1 years (range, 21-62 years), and that of Group II was 41.3 years (range, 21-57 years). Group I contained B men and 12 women, Group II contained 5 men and 15 women. The symptoms and signs in Groups I and II were similar. The duration of follow-up averaged 3.6 years (range, 1.1-16 years) in Group I and 2.3 years (range, 1.1-6 years) in Group II. RESULTS The anterior slippage in Group I, assessed by the Taillard method, was 16.1% and was corrected to 10.4% after surgery. Anterior slippage in Group II was 15.2% and was corrected to 9.8% after surgery. The fusion rate 12 months after surgery was 90% in Group I and 95% in Group II. The clinical results were analyzed by Kims criteria, according to variables on the improvement of clinical symptoms. Satisfactory results were obtained in 85% of Group I and 90% of Group II. CONCLUSIONS There was no statistically significant difference in clinical results between anterior interbody fusion and posterolateral fusion with transpedicular fixation for the treatment of isthmic spondylolisthesis in adults (P < 0.05).

Deep vein thrombosis after major spinal surgery: incidence in an East Asian population.

STUDY DESIGN A prospective study of 313 patients who underwent major spinal surgery. OBJECTIVES To determine the incidence of deep vein thrombosis after major spinal surgery in an east Asian population without antithrombotic prophylaxis. SUMMARY OF BACKGROUND DATA Spinal surgery has been associated with few thrombotic complications (2-14%) compared with other reconstructive surgeries (20-70%). It has also been well documented that the incidence of deep vein thrombosis in east Asians (10%) is lower than in westerners (20-70%) in total joint replacements. There has been no previous report on the incidence of deep vein thrombosis after reconstructive spinal surgery in east Asians. METHODS Three hundred thirteen patients who underwent major spinal surgery were evaluated prospectively. All patients were examined with duplex ultrasonography assessments of both lower extremities. No specific antithrombotic prophylaxis were used in any patients before or after surgery. RESULTS There were four patients with positive findings of deep vein thrombosis on duplex ultrasonography, and there was only one with clinically symptomatic deep vein thrombosis. The overall incidence of thrombotic complications was 1.3%, and the incidence of symptomatic deep vein thrombosis was 0.3%. CONCLUSION Considering the low rate of deep vein thrombosis, routine screening and prophylaxis for deep vein thrombosis appears unwarranted in east Asians before or after major spinal surgery.

Sacroiliac joint tuberculosis : Classification and treatment

The authors treated 16 patients with tuberculosis of the sacroiliac joint. Twelve were treated surgically and four were treated conservatively. The clinical symptoms were buttock and low back pain in all patients, and most had difficulty walking (68.6%) and had radicular pain in their lower limbs (50%). Of the 16 patients, four (15%) had associated tuberculous spondylitis, six (37.5%) had an abscess in the gluteal region, and two (12.5%) had an abscess in the inguinal region. The diagnosis was proven by pathologic specimen in 12 patients and by clinical symptoms, laboratory data, and radiologic findings in the remaining four patients. The authors classified tuberculous sacroiliitis into four types based on the clinical and radiologic findings. Types 1 and 2 were treated conservatively with chemotherapy alone, whereas Types 3 and 4 were treated with surgery and chemotherapy. Healing occurred and was evident in patients who had curettage and arthrodesis (Types 3 and 4) at a mean of 20.8 months, which was comparable with healing in the patients who had chemotherapy alone that occurred at a mean of 23.5 months (Types 1 and 2). The authors suggest that the new classification will be helpful in determining the therapeutic plan of tuberculous sacroiliitis.

Hypersensitivity to RF fields emitted from CDMA cellular phones: A provocation study

With the number of cellular phone users rapidly increasing, there is a considerable amount of public concern regarding the effects that electromagnetic fields (EMFs) from cellular phones have on health. People with self-attributed electromagnetic hypersensitivity (EHS) complain of subjective symptoms such as headaches, insomnia, and memory loss, and attribute these symptoms to radio frequency (RF) radiation from cellular phones and/or base stations. However, EHS is difficult to diagnose because it relies on a persons subjective judgment. Various provocation studies have been conducted on EHS caused by Global System for Mobile Communications (GSM) phones in which heart rate and blood pressure or subjective symptoms were investigated. However, there have been few sham-controlled provocation studies on EHS with Code Division Multiple Access (CDMA) phones where physiological parameters, subjective symptoms, and perception of RF radiation for EHS and non-EHS groups were simultaneously investigated. In this study, two volunteer groups of 18 self-reported EHS and 19 non-EHS persons were tested for both sham and real RF exposure from CDMA cellular phones with a 300 mW maximum exposure that lasted half an hour. We investigated not only the physiological parameters such as heart rate, respiration rate, and heart rate variability (HRV), but also various subjective symptoms and the perception of EMF. In conclusion, RF exposure did not have any effects on physiological parameters or subjective symptoms in either group. As for EMF perception, there was no evidence that the EHS group better perceived EMF than the non-EHS group.

Electrodiagnostic and Histologic Changes of Graded Caudal Compression on Cauda Equina in Dog

Study Design An animal model of lumbar spinal stenosis, in which the pathophysiology of this condition could be examined, was retrieved according to Delamarters method. Objectives The purpose of this study was to develop a reproducible animal model of lumbar spinal stenosis to further understanding of the long-term electrophysiologic changes, and to detect prognostic indices of the long-term anatomic and physiologic status of chronic compression of the cauda equina. Summary of Background Data Somatosensory-evoked potentials and bulbocaermosus reflexes revealed obnormalities before neurologic signs and symptoms appeared. If delayed somatosensory-evoked potentials, and bulbocavernosus reflexes, were recovered with the lapse of time, neurologic, findings showed gradual recovery. The loss of somatosensory-evoked potentials, bulbocovernosus reflexes and neurologic, histological abnormalities occured at 50% constriction of the cauda equina; at the same time, that was the critical point of possible recovery. Methods Four experimental groups, each containing six dogs. were studied, One group had a laminectomy of the sixth and seventh lumbar vertebrae only: these animals served as controls. In the three other groups, a laminectomy was performed, and the cauda equina was constricated by 25% or 75% to produced chronic compression according to Delamarters method Results Somatosensory-evoked potentials and bulbocavernosus reflexes revealed neurologic abnormalities before the appearance of neurological signs and symptoms. Constriction of more than 50% was the critical point; it reaulted in loss of evoked potentials, reflexes, neurologic deficits, and histological abnormalities. Conclusion To accurately forecast prognosis of chronic cauda equina compression, the combined diagnostic study of somatosensory-evoked potential with bulbocavernosus reflex is recommended.

Design of H 2 Controllers for Sampled-Data Systems with Input Time Delays

This paper presents a general framework based on lifting technique for sampled-data systems with input time delays. By analyzing the properties of operator-valued matrices of lifted systems with input time delays, an extended lifting technique is obtained. It is then shown that, with the proposed lifting technique, the complex behavior of the system can be illustrated by two simple lifted systems, which construct the extended lifted system. The extended lifted system has the same induced norm as that of the original system with an input time delay, since the proposed lifting technique is an isometric isomorphism. Through applying the proposed lifting technique to sampled-data systems with input time delays, the time-invariant discrete-time system with infinite-dimensional input and output spaces is obtained. The equivalent discrete-time system, which is derived from the extended lifted system, can satisfy the problem of H2 sampled-data control systems with input time delays. Simulation results are given to show that the proposed method can guarantee a more stable system response than the conventional H2 sampled-data controller for the sampled-data systems with the various input time delays.

A Computed Tomographic Analysis of Changes in the Spinal Canal After Anterior Lumbar Interbody Fusion

Thirteen patients with spondylolisthesis (six isthmic type and seven degenerative type) and ten patients with intervertebral disk herniation were treated by anterior lumbar interbody fusion. Preoperative and postoperative computed tomography (CT) scans were performed for each patient, and changes in anteroposterior (AP) diameter and lateral diameter of the dural sac, the area of the dural sac, and the amount of disk bulging were measured. The periodic tomogram was done in all patients postoperatively, and one- and two-year fusion rates were calculated. The calculations were compared with the early and late clinical results. The early clinical results after operation were excellent in 26.1%, good in 56.5%, and fair in 17.4%. The late clinical results were similar to early results. The early clinical results correlated with the changes in the spinal canal, such as an increase in AP diameter of the dural sac and a decrease in amount of disk bulging after anterior interbody fusion. There was statistical correlation between the early clinical results and the change in AP diameter of the dural sac. But the late clinical results were influenced by multiple factors including solid bony fusion.

Effects and satisfaction of medical device safety information reporting system using electronic medical record

Objectives This paper describes an evaluation study on the effectiveness of developing an in-hospital medical device safety information reporting system for managing safety information, including adverse incident data related to medical devices, following the enactment of the Medical Device Act in Korea. Methods Medical device safety information reports were analyzed for 190 cases that took place prior to the application of a medical device safety information reporting system and during a period when the reporting system was used. Also, questionnaires were used to measure the effectiveness of the medical device safety information reporting system. The analysis was based on the questionnaire responses of 15 reporters who submitted reports in both the pre- and post-reporting system periods. Results Sixty-two reports were submitted in paper form, but after the system was set up, this number more than doubled to 128 reports in electronic form. In terms of itemized reporting, a total of 45 items were reported. Before the system was used, 23 items had been reported, but this increased to 32 items after the system was put to use. All survey variables of satisfaction received a mean of over 3 points, while positive attitude, potential benefits, and positive benefits all exceeded 4 points, each receiving 4.20, 4.20, and 4.13, respectively. Among the variables, time-consuming and decision-making had the lowest mean values, each receiving 3.53. Satisfaction was found to be high for system quality and user satisfaction, but relatively low for time-consuming and decision-making. Conclusions We were able to verify that effective reporting and monitoring of adverse incidents and the safety of medical devices can be implemented through the establishment of an in-hospital medical device safety information reporting system that can enhance patient safety and medical device risk management.