Seok Hyun Lee

Deformity correction of knee and leg lengthening by Ilizarov method in hypophosphatemic rickets: Outcomes and significance of serum phosphate level

The authors evaluated 14 patients with hypophosphatemic rickets who underwent correction of a knee deformity along with a leg lengthening by the Ilizarov method. Deformity correction alone was performed in 8 femora and 4 tibiae-fibulae, and concomitant deformity correction and limb lengthening (>1.0 cm) in 9 femora and 19 tibiae-fibulae. The healing index correlated with the biochemical parameters. Knee deformities were satisfactorily corrected in all patients except one. There was a statistically significant negative correlation between the healing index and the serum phosphate level: those who had a serum phosphate level higher than 2.5 mg/dL showed a relatively rapid regenerate bone healing compared with those with less than 2.5 mg/dL. The authors conclude that a serum phosphate level of 2.5 mg/dL as a cut-off point should be considered in deciding whether deformity correction alone or with a concomitant leg lengthening should be undertaken.

Correction of apical axial rotation with pedicular screws in neuromuscular scoliosis.

Study Design A retrospective study to measure the postoperative apical axial derotation with posterior pedicle screw fixation in neuromuscular scoliosis. Objectives To determine whether the posterior only approach using pedicle screw fixation is able to accomplish apical axial derotation in neuromuscular scoliosis and if there is any difference according to severity of curve or type of disease. Summary of Background Data Literature search does not reveal anything about the rectification of apical axial rotation in neuromuscular scoliosis with the pedicle screw fixation. Methods Between January 2005 and December 2006, 24 patients (9 females and 15 males, average age 19 y) with neuromuscular scoliosis (6 cerebral palsy, 9 Duchenne muscular dystrophy, 5 spinal muscular atrophy, and 4 others) underwent posterior pedicle screw construct with correction and fusion for the treatment of progressive, symptomatic spinal deformities. Preoperative, immediate postoperative, and final follow-up radiographs were analyzed according to Cobbs angle and pelvic obliquity, whereas apical axial rotation was measured on preoperative and postoperative computerized tomography scan using Aaro-Dahlborn method from mid-sagittal plane. Twelve (9 females and 3 males) adolescent idiopathic scoliosis patients, who underwent similar operation, comprised our control group for the comparison of results. Results All the patients exhibited improved sitting balance after surgery. The mean preoperative Cobbs angle, pelvic obliquity, and apical rotation were 74, 14, and 42 degrees, whereas postoperative were 32, 6, and 33 degrees, respectively, showing significant correction in all 3 parameters. Comparison of results based on severity of curve did not reveal any statistically significant difference (P=0.255) in correction of apical axial rotation among group I, group II, and group III. A similar apical rotational correction was recorded in different disease groups (P=0.295). Comparing the results between neuromuscular and idiopathic scoliosis groups, we could not find any statistically significant difference. Conclusions Our results indicate that apical axial derotation can be well achieved with posterior only pedicle screw fixation in patients with neuromuscular scoliosis without any need for an anterior release procedure.

Relationship between lateral subluxation and widening of medial joint space in Legg-Calve-Perthes disease

Fifty-five patients (61 affected hips and 49 unaffected hips) with Perthes disease were reviewed to evaluate the relationship between widening of medial joint space and lateral subluxation of the femoral head in radiographs. The components of the medial joint space were evaluated by using T1, T2, proton, and Gd-enhanced T1WI magnetic resonance images (MRI). The widened medial joint space in radiographs was filled with overgrown cartilage at the initial stage (27 hips) in MRI, with both overgrown cartilage and widened true medial joint space at the fragmentation stage (23 hips) and widened true medial joint space at the healing stage (11 hips). Between affected hips and unaffected hips, the mean difference of medial joint space in radiographs between hips at the initial stage and at the fragmentation stage was 2 and 4.5 mm, respectively; the mean difference in percentage of lack of coverage of the femoral head between hips at the initial stage and at the fragmentation stage was 3 and 15%, respectively. During the healing stage, widening of the medial joint space decreased or normalized because of ossification of overgrown cartilage despite the existence of lateral subluxation because of coxa magna. We concluded that widening of the medial joint space may be used as an index of lateral subluxation at only the fragmentation stage in Perthes disease.

Origin of lumbar spinal roots and their relationship to intervertebral discs: a cadaver and radiological study.

Previous studies on the anatomy of the lumbar spine have not clarified the precise relationship of the origin of the lumbar roots to their corresponding discs or their angulation to the dural sac. We studied 33 cadavers (25 formalin-preserved and eight fresh-frozen) and their radiographs to determine these details. All cadavers showed a gradual decrease in the angle of the nerve root from L1 to S1. The origin of the root was found to be below the corresponding disc for the L1 to L4 roots. In the formalin-preserved cadavers 8% of the L5 roots originated above, 64% below and 28% at the L4/L5 disc. In the fresh cadavers the values were 12.5%, 62.5% and 25%, respectively. For the S1 root 76% originated above and 24% at the L5-S1 disc in the formalin-preserved cadavers and 75% and 25%, respectively, in the fresh cadavers.A herniated disc usually compresses the root before division of the root sleeve. Thus, compression of the thecal sac before the origin of the root sleeve is common for L1 to L5 whereas compression at the root sleeve is common for S1. Our findings are of value in understanding the pathophysiology of prolapse of the disc and in preventing complications during surgery.

Comparison of MRI with subchondral fracture in the evaluation of extent of epiphyseal necrosis in the early stage of Legg-Calvé-Perthes disease.

We reviewed 20 patients in the early stage of Legg-Calvé-Perthes disease who showed a subchondral fracture line in radiographs. All 20 patients underwent magnetic resonance imaging (MRI) within 2 months after the first symptoms. Follow-up MRI after treatment was performed in 10 patients. The subchondral fracture line in radiographs and serial T1-weighted image was used to measure the extent of the epiphyseal necrosis volumetrically. These extents in the early stage were compared with those in the late stage for determination of prognostic significance. The intensities of coronal MRIs under the subchondral fracture were not homogeneous. The uninvolved epiphysis also showed nonhomogeneous intensities because the posterior column revealed higher intensity compared with the anterior column. The extent of the subchondral fracture line is more accurate in predicting the amount of eventual necrosis than is the extent of necrosis in MRI, which does not have a consistent correlation.

All-optical binary half adder using SLALOMs

All-optical binary half adder is demonstrated using two semiconductor laser amplifiers in a loop mirror (SLALOMs) which have functions of XOR and AND, respectively. The operation of the proposed scheme is experimentally verified with two input data streams.

The sagging rope sign in achondroplasia- : different from Perthes' disease

ObjectiveThe sagging rope sign is a radio-opaque line, seen on radiographs of the hips, with Perthes’ disease. The main purpose of this study was to determine the incidence, cause and importance of this sign in achondroplasia, and to reveal how it differs from in Perthes’ disease.DesignSerial radiograms, along with 2-dimensional and 3-dimensional CT images were studied in 42 achondroplasic patients.PatientsForty-two achondroplasic patients, reported at our institute (for routine outpatient consultation, spine surgeries, deformity corrections, limb-lengthening procedures) were included in this study. There were 26 males and 16 females.ResultsThe sign was observed bilaterally, in all patients. Evaluation of CT images revealed spherical heads, with presence of circumferential overhang in all hips. This circumferential overhang, seen on 3-D CT scan, corresponded to the sagging rope sign on radiographs.ConclusionsPresence of the sagging rope sign in bilateral hips is a characteristic feature of achondroplasia. It usually appears before epiphyseal closure. Its cause, incidence, and nature differ from Perthes’ disease, and its presence does not carry a bad prognosis in achondroplasia.

Pelvic fracture after scoliosis surgery in osteogenesis imperfecta: a case report.

Literature, describing scoliosis in patients of osteogenesis imperfecta (OI), favors operative treatment as soon as possible in the form of fixation with instrumentation and fusion to prevent curve progress and pulmonary function deterioration. There are various complications associated with the treatment of scoliosis in OI before, during, and after surgery because of poor bone quality in such patients. We presented a case report of stress-induced transverse fracture of both iliac wings after scoliosis surgery in a 16-year-old girl with OI, who was treated conservatively. Owing to unusual symptoms and continuous dull pain in her back, the diagnosis was delayed during which the conditions made her life miserable. This report also suggests that a stress fracture should be on high suspicion in OI patients when they present with minor difference in the nature of pain.

Relationship of Risser Sign with Chronological Age, Menarche in Elementary, Middle, and High School Students in Korea

Purpose: This study was undertaken to investigate the relationship between the Risser sign and chronological age and menarche in elementary, middle, and high school students, and to investigate the reliability of the Risser sign. Materials and Methods: We reviewed 1,870 spine standing AP X-rays, which included the iliac crest. We tried to identify a correlation between the Risser stage and chronological age, and between Risser stage and menarche. In addition, we investigated inter-observer error in the determination of Risser stage. Results and Conclusion: The mean ages of Risser 1, 2, 3 and 4 female students were 12.9, 13.3, 13.6, and 14.3 years, and the mean ages of Risser 1, 2, 3 and 4 male students were 14.0, 14.3, 14.5, and 15.6 years (Spearmans rho=0.560, p

All-optical serial-parallel data converters using optical interferometers

We propose new simple and easily expandable schemes of all-optical serial-to-parallel and parallel-to-serial data converters based on optical interferometers. We experimentally demonstrate the proposed data converters.