Chang Yong Hur

Validation of a simple radiographic method to determine variations in pelvic and acetabular cup sagittal plane alignment after total hip arthroplasty

Background and purposeOrientation of acetabular component, influenced by pelvic tilt, body position, and individual variations affects the outcome following total hip arthroplasty (THA). Currently available methods of evaluation are either imprecise or require advanced image processing. We analyzed intersubject and intrasubject variability of pelvic tilt, measured by sagittal sacral tilt (ST) and its relationship with acetabular component tilt (AT) by using a simple method based on standard radiographs.Materials and methodsST was measured on lateral radiographs of pelvis including lumbosacral spine obtained in supine, sitting, standing, and lateral decubitus position for 40 asymptomatic THA patients and compared to computed tomography (CT) data obtained in supine position. AT was measured on lateral radiographs (measured acetabular tilt: MAT) in each position and compared to measurement of AT on CT and an indirectly calculated AT (CAT).ResultsMean ST changed from supine to sitting, standing, and lateral decubitus positions as follows: 26.5 ± 15.5° (range 4.6–73.4°), 8.4 ± 6.2° (range 0.6–24.5°), and 13.4 ± 8.4° (range 0.1–24.2°; p < 0.0001, p = 0.002, p = 0.006). The MAT on radiographs was not significantly different from the MAT measured on CT (p = 0.002) and the CAT (p = 0.06). There is a good correlation between change in ST and MAT in sagittal plane (r = 0.93).ConclusionMeasurement of ST on radiographs is a simple and reliable method to track changes in pelvic tilt in different body positions. There is significant intersubject and intrasubject variation of ST and MAT with postural changes and it may explain causes of impingement or instability following THA, which could not be previously explained.

False negative and positive motor evoked potentials in one patient: is single motor evoked potential monitoring reliable method? A case report and literature review.

Study Design. A case report and literature review. Objective. To report a false negative and delayed positive motor-evoked potential (MEP) in 1 patient. Summary of Background Data. An unreliable MEP can result in fatal outcomes because surgeons have recently begun to depend on the MEP for intraoperative decision-making. Methods. We report a case of a false MEP during scoliosis surgery that showed false negative and positive MEPs during a series of operations. Results. A 23-year-old man with a history of spondyloepiphyseal dysplasia presented with severe kyphoscoliosis. The initial neurologic examination did not reveal any neurologic abnormalities. Surgical correction and fusion were performed with transcranial MEP monitoring. During the entire procedure, the MEP did not reveal any signs of cord injury. However, lower limb paralysis and paresthesia was observed when the patient awakened. After 2 additional surgical procedures to recover the neurologic deficit, the MEP did not show any signs of cord injury but the patients neurologic status had recovered slightly. At postoperative day 8, the neurologic status recovered, and a third operation was performed to fix the long rods. However, there were abnormal amplitudes in both lower limbs but the patients neurologic status was almost normal. Conclusion. From our experience of false negative and positive MEP in 1 patient, it is concluded that undesirable events can occur with use of MEP in scoliosis or other spinal surgery. Therefore, we warn the surgeons too heavily rely on the MEP monitoring, and propose a further prospective study as well as use of alternative method that can improve the reliability of single MEP.

Correlation of pelvic orientation with adult scoliosis.

Study Design Prospective analysis of elderly volunteers with adult scoliosis. Objectives To analyze the correlation between the sagittal pelvic parameters and adult scoliosis. Summary of Background Data There are little data on the relationship between the sagittal pelvic parameters and adult scoliosis. Methods The study group comprised 108 elderly volunteers (21 men and 87 women). All underwent anteroposterior and lateral radiographs of whole spine including hip joints. The participants were classified into 3 groups: normal (Cobb angle <10 degrees), low grade (Cobb angle 10 to 19 degrees), and high grade (Cobb angle ≥20 degrees). The radiographic parameters were magnitude, location and direction of curves, sacral slope, pelvic tilting, pelvic incidence, S1 overhang, thoracic kyphosis, lumbar lordosis, and C7 plumbline. Statistical analysis was performed to identify the significant differences between the groups. Analysis of variance and Pearson correlation coefficient were used to determine the significance. Results The mean age and Cobb angle of the participants was 73 years (range: 61 to 87 y), and 11.2 degrees (range: 0.3 to 36.3 degrees), respectively. There were no significant differences in the sacral slope, thoracic kyphosis, and lumbar lordosis between the 3 groups (P>0.05, analysis of variance). The mean pelvic tilting of the high-grade or low-grade groups was significantly higher than that of the normal group (P<0.0001, P=0.003, Tukey HSD post hoc test). The high-grade group had significantly higher pelvic incidence than either the low-grade or normal groups (P=0.016, P<0.0001), and the low-grade group had higher pelvic incidence than the normal group (P<0.0001). The high-grade or low-grade groups had a significantly higher S1 overhang than the normal groups (P<0.0001, P=0.002). Comparing the C7 plumbline, high-grade or low-grade groups had a significantly higher value than normal groups (P<0.0001, P=0.012). The pelvic incidence, pelvic tilting, and S1 overhang were significantly correlated with the magnitude of curvature (r=0.592, P=0.0001; r=0.434, P=0.0001; and r=0.461, P=0.0001, respectively). Conclusions There was a significant correlation between the sagittal pelvic parameters and adult scoliosis in elderly volunteers. There was a significant difference in the pelvic incidence between the normal, low-grade, high-grade adult scoliosis groups. The pelvic tilting and S1 overhang of the high-grade or low-grade groups were significantly higher than the normal group. These 3 parameters were also associated with the magnitude of curvature.

Upper cervical spine instability in pseudoachondroplasia.

Background: Pseudoachondroplasia (PSACH) is a rare autosomal dominant skeletal dysplasia associated with os odontoideum and atlantoaxial instability. This study aims to define the characteristics of upper cervical spine instability in patients with PSACH and analyze the relation between the incidence of upper cervical instability and os odontoideum. Methods: Fifteen patients (10 women and 5 men) with PSACH of Korean ethnicity with mean age of 23.7 years (range, 3-44 years) at presentation to our hospital with varied complaints, including short stature, limb deformity, neck pain, and neurological symptoms, were evaluated clinicoradiologically for upper cervical spine instability. The patients were separated into group 1 (n = 9) with os odontoideum and group 2 (n = 6) without os odontoideum. Comparisons were made using parameters such as instability index, rotational instability, atlantodens interval and space available for cord, and analysis done to correlate cervical instability with age and Japanese Orthopedic Association (JOA) score. Results: Significant differences were found statistically when the 2 groups were compared on the basis of the space available for the cord (SAC), JOA scoring, and rotational instability. Linear relationship was found between instability and age and JOA score. Incidence of os odontoideum was 60% in our study group. Conclusions: Os odontoideum led to an increase in the incidence of upper cervical spine instability. Instability increased with the age. The presence of os odontoideum and atlantoaxial instability did not warrant for surgery because no signs of cervical myelopathy developed or progressed in our patients during the follow-up period, but these patients should undergo regular clinical and radiological evaluation. Level of Evidence: Level IV prognostic study.

The Effect of Platelet Rich Plasma from Bone Marrow Aspirate with Added Bone Morphogenetic Protein-2 on the Achilles Tendon-Bone Junction in Rabbits

Background To determine if exogenously injected bone marrow derived platelet-rich plasma (PRP) plus bone morphogenetic protein (BMP)-2 could accelerate the healing of bone-tendon junction injuries and increase the junction holding strength during the early regeneration period. Methods A direct injury model of the bone-tendon junction was made using an Achilles tendon-calcaneus bone junction in a rabbit. In the PRP/BMP-2/fibrin group, 0.05 mL of bone marrow derived PRP and 100 ng/mL of BMP-2 both incorporated into 0.1 mL of fibrin glue were injected into Achilles tendon-calcaneus bone junctions. The effect of the intervention was tested by comparing the results of an intervention group to a control group. The results of biomechanical testing, and histological and gross analyses were compared between the 2 groups at the following time points after surgery: 2 weeks, 4 weeks, and 8 weeks. Results Histologic examinations showed that woven bone developed in tendon-bone junctions at 2 weeks after surgery in the PRP/BMP-2/fibrin group. Mechanical test results showed no significant difference between the PRP/BMP-2/fibrin and control groups at 2 and 4 weeks after surgery, but the mean maximal load in the PRP/BMP-2/fibrin group was significantly higher than in the control group (p < 0.05) at 8 weeks after surgery. Conclusions Bone marrow derived PRP and BMP-2 in fibrin glue accelerated healing in a rabbit model of tendon-bone junction injury.

Centroid method: reliable method to determine the coronal curvature of scoliosis: a case control study comparing with the Cobb method.

Study Design. Observational study with three examiners. Objective. To compare the reliability of the Cobb and centroid methods. Summary of Background Data. The Cobb method is considered to be the gold standard in scoliosis measurement despite its low reliability. In adolescent idiopathic scoliosis (AIS) patients, the centroid method can be a good method for measuring scoliosis. Methods. Sixty whole spine postero-anterior radiographs were collected to compare the reliability of the Cobb and centroid methods in AIS patients. Sixty radiographs were measured twice by each of the three examiners using the two measurement methods. The data were analyzed statistically to determine the inter- and intraobserver reliability. Result. In comparisons of inter- and intraobserver reliability of all 60 radiographs, the inter- and intraclass coefficients (ICCs) were higher in the centroid (>0.969) than in the Cobb method (>0.832), although both were in the excellent range. The mean absolute difference (MAD) values were higher in the Cobb method (<7.15° vs. <3.75°), and >5° in five comparisons. Regarding measures of mismatched radiograms, the inter- and intraobserver MAD values were higher in the Cobb method (<9.81° vs. <3.82°), and >5° in six comparisons. And, the ICCs were higher in the centroid method (>0.972) than the Cobb method (>0.758). In immature radiograms, the ICCs were higher in the centroid (>0.973) than in the Cobb method (>0.764), even though it was in the excellent range. And, the inter- and intraobserver MAD values were higher in the Cobb method (<8.49° vs. <3.99°), and >5° in seven comparisons. Conclusion. The centroid method is more reliable for measuring scoliosis in AIS than the Cobb method, and it can substitute the Cobb method, which showed high variability.

Correlation between facial asymmetry, shoulder imbalance, and adolescent idiopathic scoliosis.

We conducted a prospective cross-sectional study to examine the correlation between facial asymmetry, shoulder imbalance, and adolescent idiopathic scoliosis. Sixty-nine adolescent idiopathic scoliosis patients and 29 healthy volunteers were enrolled in this study. All patients underwent whole-spine standing anteroposterior radiographs and frontal cephalograms. Patients were divided into mild, moderate, and severe groups depending on Cobb angle (10°-25°, 25°-40°, and >40°, respectively). Facial measurements included maxilla height difference, ramus length difference, and anterior nasal spine-menton angle. Shoulder measurements included coracoid height difference, clavicular angle, clavicle-rib intersection difference, and radiographic shoulder height.The anterior nasal spine-menton angle in the severe group (>40°) was higher than in the other groups (P<.05), as was the clavicle-rib intersection difference (P<.05). In addition, the magnitude of the curve showed a possible correlation with the anterior nasal spine-menton angle and clavicle-rib intersection difference in scoliosis patients (r=0.433 and r=0.511, respectively). According to different curve patterns, the anterior nasal spine-menton angle and clavicle-rib intersection difference were significantly higher in the double thoracic group than in the other groups (P<.05). In the correlation analysis, the ramus length difference and anterior nasal spine-menton angle had a possible correlation with the coracoid height difference, clavicular angle, radiographic shoulder height, and clavicle-rib intersection difference (P<.05).

Changes in Level of the Conus after Corrective Surgery for Scoliosis: MRI-Based Preliminary Study in 31 Patients

Background Detection of postoperative spinal cord level change can provide basic information about the spinal cord status, and electrophysiological studies regarding this point should be conducted in the future. Methods To determine the changes in the spinal cord level postoperatively and the possible associated factors, we prospectively studied 31 patients with scoliosis. All the patients underwent correction and posterior fusion using pedicle screws and rods between January 2008 and March 2009. The pre- and postoperative conus medullaris levels were determined by matching the axial magnetic resonance image to the sagittal scout image. The patients were divided according to the change in the postoperative conus medullaris level. The change group was defined as the patients who showed a change of more than one divided section in the vertebral column postoperatively, and the parameters of the change and non-change groups were compared. Results The mean pre- and postoperative Cobbs angle of the coronal curve was 76.80° ± 17.19° and 33.23° ± 14.39°, respectively. Eleven of 31 patients showed a lower conus medullaris level postoperatively. There were no differences in the pre- and postoperative magnitude of the coronal curve, lordosis and kyphosis between the groups. However, the postoperative degrees of correction of the coronal curve and lumbar lordosis were higher in the change group. There were also differences in the disease entities between the groups. A higher percentage of patients with Duchene muscular dystrophy had a change in level compared to that of the patients with cerebral palsy (83.3% vs. 45.5%, respectively). Conclusions The conus medullaris level changed postoperatively in the patients with severe scoliosis. Overall, the postoperative degree of correction of the coronal curve was higher in the change group than that in the non-change group. The degrees of correction of the coronal curve and lumbar lordosis were related to the spinal cord level change after scoliosis correction.

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