The biomechanical study of the bone-prosthesis interface stability according to the difference of types of porous-coated acetabular implant / 대한정형외과학회잡지

PURPOSE: To analyze the effects of implant design on the primary stability and the contact between bone and prosthesis of three different porous coated acetabular implants. MATERIALS AND METHODS: The distal part of sixty bovine femurs were employed. 52 mm acetabular cups were inserted tightly after 2mm under-reaming. Trilogy acetabular cups were inserted in Group I, Mallory head finned RingLoc cups in Group II, Duraloc spiked cups in Group III. The gaps between the acetabular cups and the bones were measured on the radiography. The axial compression test and rotation test were performed using Instron. RESULTS: The gaps between the acetabular cup and bone of Gorup I and II was significantly smaller than Group III at its central adjacent and peripheral area (p0.05) . The mean torque of 1 degree rotation test was higher in the Group III than in the group I and II without statistical significance (p>0.05) . The mean torque of 2, 3 and 5 degree rotation test was highest in Group II among three, but there were no statistical differences among three groups (p>0.05) . CONCLUSION: Triology and Mallory-Head cup can be assumed to have better primary stability than Duraloc cup. And additional fin or spikes attached on the acetabular implant couldn't enhance the primary bone-prosthesis interface stability.

Ultrasonographic Morphology of Hip in Korean Neonates / 대한정형외과학회잡지

PURPOSE: To confirm the validity of static measurements of ultrasonographic morphometric techniques and compare the normal ultrasonographic morphology of Korean neonates with that of reported series in the literature from different parts of the world. MATERIALS AND METHODS: One hundred and twelve normal neonates (224 hips) of less than four weeks old had ultrasonographic examinations and static measurements in copies of coronal images, such as Graf's angle, angle, Morin's head coverage percentage and cartilaginous head size. The measurements were performed twice by two surgeons at more than one week's interval and the mean values of static measurements were compared with series on Caucasians, Hong Kong Chinese, and Japanese. RESULTS: Means of angle , angle , head coverage percentage and cartilaginous head size were 60.11+/-5.0degrees, 45.82+/-4.08degrees, 57.43+/-6.89%, 14.99+/-1.16 mm, respectively. The interobserver and intraobserver variance was not significantly different. CONCLUSION: Static measurements in our ultrasonographic morphometric techniques reveal acceptable intraobserver and interobserver variance, with Korean neonates showing to have definitely lower angle and high head coverage percentage than Japanese or Caucasian neonates reported in the literature.

The Natural History of Asymptomatic Early Avascular Necrosis of the Femoral Head / 대한정형외과학회잡지

We studied the natural history of asymptomatic early avascular necrosis of the femoral head in forty-three patients(forty-three hips) who had been treated with arthroplasty due to progressed avascular necrosis of femoral head but had no symptoms in the other side. All initial lesions were classified with Ficat staging and International classification(ARCO). The duration until symptom onset and radiologic evidence of disease progression were evaluated. The average follow up period was over 37 months. Among forty-three hips, twenty-nine cases(67.4%) remained asymptomatic until last follow up but fourteen cases(32.6%) were symptomatic during the follow up, and twenty-six cases(60.5%) did not progress on the radiography but seventeen cases(39.5%) progressed to Ficat stage 3 or 4. Fifteen cases of IA, IIA, IB-cental and II B-central without lateral lesion did not occur symptom and didnt progress to Ficat stage 3 or 4 over a period of average 47 months(24-71 months). But fourteen cases of IB, IC, g B and II C progressed to Ficat stage 3 or 4 and they were all lateral lesion. These results suggest careful observation only can be done in the case of small involvement(less than 15%) and medial or central lesion relatively over a long period of time but for the large involvement(more than 30%) and especially lateral lesion, aggressive surgical treatment may be considered even though the early stage of disease for the prevention of progression. However it will need more period of time to accurately compare the results of various methods of treatment.