Biomedical subjects

K H Koo

Publications and source records attributed to K H Koo.

27 records · Page 2Linked to original sources

PubMed1995

Preventing collapse in early osteonecrosis of the femoral head. A randomised clinical trial of core decompression.

We performed a randomised trial on 37 hips (33 patients) with early-stage osteonecrosis (ON). After the initial clinical evaluation, including plain radiography and MRI, 18 hips were randomly assigned to a core-decompression group and 19 to a conservatively-treated group. All the patients were regularly followed up by clinical evaluation, plain radiography and MRI at intervals of three months. Hip pain was relieved in nine out of ten initially symptomatic hips in the core-decompression group but persisted in three out of four initially painful hips in the conservatively-treated group at the second assessment (p < 0.05). At a minimum follow-up of 24 months, 14 of the 18 core-decompressed hips (78%) and 15 of the 19 non-operated hips (79%) developed collapse of the femoral head. By survival analysis, there was no significant difference in the time to collapse between the two groups (log-rank test p = 0.79). Core decompression may be effective tin symptomatic relief, but is of no greater value than conservative management in preventing collapse in early osteonecrosis of the femoral head.

Adolescent↗

PubMed1995

Quantifying the extent of osteonecrosis of the femoral head. A new method using MRI.

In a randomised trial comparing core decompression with conservative treatment we tested the hypothesis that the extent of necrosis at the initial MRI predicts the subsequent risk of collapse of the femoral head. After the initial clinical evaluation, including plain radiography and MRI, 37 hips with early-stage osteonecrosis (ON) in 33 patients were randomly assigned to a core-decompression group or a conservatively-treated group. All were followed regularly by clinical evaluation, plain radiography and MRI at intervals of three months. The extent of ON was estimated on the basis of abnormal signal intensity in the weight-bearing portion of the femoral head as determined from a combination of coronal and sagittal MRIs. The arc of the necrotic portion in the mid-coronal image (A) and that in the mid-sagittal image (B) were used to quantify the extent of necrosis by the formula: (A/180) x (B/180) x 100. There was a strong correlation between this index and the risk of collapse before and after adjustment for age, gender, stage and treatment group. We conclude that the extent of the necrotic portion ascertain by this method is a major predictor of future collapse. We propose a systematic method of determining the index of the necrotic portion which may be clinically useful in the management of early-stage ON of the femoral head.

Femur Head↗

PubMed1994

Angiography, scintigraphy, intraosseous pressure, and histologic findings in high-risk osteonecrotic femoral heads with negative magnetic resonance images.

One hundred twenty-six hips of 68 patients who were suspected of having osteonecrosis or being at risk for osteonecrosis were studied with magnetic resonance (MR) imaging. Abnormal patterns on MR imaging characteristic of osteonecrosis were observed in 98 hips. The remaining 28 hips (22 patients) with negative MR images underwent superselective angiography of the medial femoral circumflex artery. Angiography showed interruption of the superior retinacular arteries in 13 hips (12 patients), including 6 of 7 symptomatic hips. Bone scans were performed on 8 of 13 hips angiographically positive for osteonecrosis. Decrease of radionuclide uptake (cold lesions) was observed in all 8 of these femoral heads. Thirteen femoral heads with interruption of superior retinacular arteries underwent intraosseous pressure measurement and core biopsy. Intraosseous pressure was elevated in 11 hips. The results of histologic study showed evidence of early necrosis in 10 femoral heads. This study indicates that there are a considerable number of femoral heads at high risk, even when they have negative MR images. They do, however, show positive findings on angiography, scintigraphy (cold lesions), intraosseous pressure measurement, and histologic study.

Adolescent↗

PubMed1991

Morphologic and biomechanical study of avascular necrosis of the femoral head.

Radiologic review and uniaxial compression tests of 1 cm3 cubes of avascular and subjacent portions of 64 femoral heads of 51 patients with idiopathic avascular necrosis of the femoral head were performed to determine the morphologic and biomechanical changes with progression of the disease. Cases were divided into three groups according to the simple radiographic findings: group I (precollapse), group II (collapse), and group III (advanced collapse with secondary degenerative arthritis). Fourteen group I, 36 group II, and 14 group III specimens were identified. In addition to the simple radiographs, 16 magnetic resonance images were reviewed. In group I, there was no significant difference of yield and maximum stress, and modulus of elasticity between avascular and subjacent portions below the reactive rim. In group II, the above parameters showed lower values in the avascular portion than in the subjacent portion (P less than .05). In group III, maximum stress of the avascular portion showed significantly higher value than that of the subjacent region (P less than .05). In groups II and III, a major crack was observed in the subchondral area in 14 specimens and in the deep avascular and reactive junction in 36 specimens. Bone densitometry data suggested higher mineral content indicative of more sclerosis in the deep crack group. These findings might suggest that different biomechanical properties in the subchondral crack group and interface crack group might contribute to varieties in clinical manifestations. Later sclerotic changes and aspherical collapse of the femoral head might play a large role in the development of secondary degenerative arthritis of the hip joint.

Absorptiometry, Photon↗

PubMed1989

[Experimental infection of Paragonimus iloktsuenensis to albino rats, dogs and cats].

This study was performed to observe the susceptibility of dogs and cats as definitive hosts of Paragonimus iloktsuenensis. The metacercariae of this fluke were obtained from Sesarma dehaani collected at a focus near the mouth of Sumjin river in November, 1986 and February, 1987. The larvae isolated from the crabs were introduced per os into 7 albino rats, 2 dogs and 3 cats. The adults were recovered from the experimental animals, and they were morphologically observed and measured. The results were as follows: 1. The recovery rate of adult worms at 42 days after infection was 53.3% from three albino rats, 21.0% from a dog and 12.7% from two cats. Most of the worms were recovered from the worm capsules in the lungs. 2. The size of worms recovered from albino rats, a dog, and cats 42 days after infection averaged 6.3 x 3.2 mm, 6.3 x 3.0 mm, or 6.2 x 3.5 mm, respectively. There were little differences in the morphology of worms by different experimental animals. 3. The size of eggs from a dog was 88.9 x 49.3 microns, and that from cats was 84.3 x 53.7 microns on average. Dogs and cats were good definitive hosts of P. iloktsuenensis. This fact suggests that human infection by this fluke may be possible if the metacercariae were ingested.

Animals↗

PubMedDate not supplied

Relationship between lateral subluxation and widening of medial joint space in Legg-Calvé-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.

Adolescent↗

PubMedDate not supplied

Classification of metaphyseal change with magnetic resonance imaging in Legg-Calvé-Perthes disease.

Seventy-eight patients (85 affected hips and 71 unaffected hips) with Legg-Calvé-Perthes disease were included in this study to evaluate the metaphyseal change in radiographs and magnetic resonance imaging (MRI) and to define the type of the metaphyseal cyst according to presence or absence of the epiphyseal involvement. The content of the metaphyseal cyst was evaluated by using T1,T2, proton, and gadolinium-enhanced T1-weighted MRI scans. Among 85 hips, there were no changes in 32 hips, marrow edema in 13 hips, false cyst with epiphyseal involvement in 28 hips, and true cyst without epiphyseal involvement in 12 hips. Granulation tissue was found in the false cysts and water-rich fibrotic tissue was found in the true cysts based on the MRI scans. The metaphyseal change in MRI scans was shown in 71% of groups 3 and 4 and in 35% of groups 1 and 2 according to the Catterall classification, and 52% of group A, 56% of group B, and 86% of group C according to the Herring classification. Of the 30 hips at the avascular stage, 33% showed metaphyseal cyst in MRI scans. Of the 53 hips at the fragmentation stage, 60% showed the metaphyseal cyst.

Adolescent↗

PubMedDate not supplied

Preclinical application of radioimmunoguided surgery using anti-carcinoembryonic antigen biparatopic antibody in the colon cancer.

Radioimmunoguided surgery (RIGS) has been known as a sophisticated tool to detect micrometastasis intraoperatively. A preclinical model of RIGS was designed to test the possible clinical applicability of the biparatopic antibody in detecting colorectal cancer. The biparatopic antibody was constructed using two anti-carcinoembryonic antigen (CEA)-specific antibodies, T84.66 and PR1A3, reacting against two different epitopes. (125)I-labeled biparatopic antibody was introduced via the principal colonic arteries at the end of operation in 10 operable patients with colon cancer. After 24 h, the radioactivities of the tumors and lymph nodes were counted using the gamma-detecting probe. The radioactivity count was performed ex vivo. The accurate detection in the primary tumors and metastatic lymph nodes were 100 and 88.7% respectively. False-positive detections occurred in 24 of 256 lymph nodes (9.4%), whereas false-negative detections occurred in 5 of them (2%). The most frequent cause of false-positive detection was dissociated radionuclides trapped in the lymphatic tissues. False-negative detections occurred mainly from weak targeting by radiolabeled antibody, probably due to weak expression of tumor CEA. Conclusively, as most detection errors appear to be reduced within 3 days in vivo, the biparatopic antibody can efficiently be applied to the clinical RIGS, thereby facilitating accurate detection and removal of occult cancer foci in colorectal cancer.

Antibodies↗

PubMedDate not supplied

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.

Child↗