Biomechanical Analysis of Proximal Fitting-Distal Filling Stem and Proximal Fitting- Distal Tapered Stem in Cementless Hip Prosthesis: A 3 Dimensional Finite Element Study / 대한정형외과학회잡지

PURPOSE: This study was undertaken to compare the initial micromotion and stress shielding of a "fit and fill" stem to a "proximal fitting and distal tapered" stem in the early postoperative period using the load simulating single leg stance and stair climbing. MATERIALS AND METHODS: Using the data from 3-D human CT scan, authors developed two types of 3-dimensional finite element total hip replacement model of proximal femur, which were inserted with a "fit and fill" stem and a "proximal fitting and distal tapered" stem. The constructions of stems were based on the OmnifitTM stem (about 13,000 element & 20,000 nodes). We compared micromotion, maximal principal stress and strain energy of each stems. RESULTS: The results indicate that micromotion in a fit and fill stem were slightly lower than that of a tapered stem, especially in stair climbing over that in the single leg stance. The maximum principal stress on the cortex of femur was slightly higher in a tapered stem in the case of single leg stance, and 2 times higher in the case of stair climbing. Strain energy also was much higher in a tapered stem in both single leg stance and stair climbing gait. CONCLUSION: These findings indicate that a tapered stem design could provide more favorable biomechanical benefits rather than a fit & fill stem after cementless total hip replacement.

Comparative Functional Evaluation of Cementless Bipolar Endoprosthesis and Cementless Total Hip Replacement Arthroplasty in Avascular Necrosis of the Femoral Head in Adult / 대한정형외과학회잡지

In these days, there are two main ways in the treatment of the avascular necrosis of the femoral head in adult by prosthetic replscement; total hip replacement and bipolar endoprosthesis. So far, no study has been performed on the post-operative functional evaluation of them. Therefore it is difficult to decide which one is preferred to the other in the treatment of avascular necrosis of the femoral head in adult. In order to evaluate the functions of the prosthetic joints, the authors reviewed the results of 18 cases of cementless bipolar endoprosthesis(abbreviated as CBE) and 22 csses of cementless total hip replscement arthroplasty(abbreviated as CTHRA), performed at the Department of Orthopedic Surgery, Seoul National University Hospital, during the period from February, 1984 to May, 1986. The following results were obtained. 1. The average ages of CBE and CTHRA groups at the time of operation were 48.5 years and 37.5 years, respectively. 2. The average follow-ups of CBE and CTHRA were 15.7 months and 30.5 months, respectively. 3. By Meyer's modification of Marcus and Enneking classification, the sverage stages of CBE and CTHRA groups were 3.7 and 4.4 respectively. 4. According to Harris hip rating score system, Harris scores were increased as much as 30.5 in CBE group and 30.6 in CTHRA group. 5. In the aspects of functional improvement and relief of pain, the two groups showed no significant difference. However, the operation was essier, and the damage to the acetabular bone was less in CBE group. For these reasons, CBE was believed to be the preferred choice of treatment of avascular necrosis of femoral head in adult.

Incidence and Clinical Significance of Deep Vein Thrombosis after Cementless Total Hip Replacement in Korean Patient Population

We studied the incidence of deep vein thrombosis in the 110 Korean patients who had Porous Coated Anatomic (P.C.A.) cementless total hip replacement. The diagnosis of deep vein thrombosis was made by roentgenographic venography. The perfusion lung-scanning was done to make a diagnosis of pulmonary embolism. Our findings showed that there was an unusually low incidence (7 per cent) of deep vein thrombosis in our unprotected patient group. They also revealed that some factors that are believed to be relevant to thrombosis were conspicuously rare in this series. In view of this fact, we re-evaluated the so-called risk factors and came to a conclusion that some of them-such as advanced age, venous valve number; coagulation assay data, orthopedic diagnosis, preoperative limitation of mobility, hypertension and blood group-that have been claimed to be relevant in fact seem to be irrelevant to deep vein thrombosis.

Revision Arthroplasty with Cementless Total Hip Replacement / 대한정형외과학회잡지

It is well known that the incidence of revision arthroplasty for the loosened total hip has been progressively increasing recently. And the problem is that the loosening rate of revision arthroplasty for the failed total hip replacement is much higher as compared with that of primary total hip replacement. In revision arthroplasty, Amstutz, in 1982, reported 9% incidence of mechanical failure and 43% incidence of femoral and 61% incidence of acetabular progressive radiolucencies with follow-up for an average of 2.1 years, and Pellicci, in 1985, reported 29% incidence of failure for total hip replacement that have been revised once in the radiolucent zone with the follow-up for an average 8.1 years, and Kavanagh, in 1985, reported that probable loosening occurred in 25% of revised acetabular components with follow-up for an average of 4.5 years. Cementless total hip replacement is successful in more than 90 of the primary cases for the last 5 years in our department. Therefore, not only in primary total hip replacement but also in the revision, it seems to be reasonable to perform the cementless total hip replacement as an alternative, particularlly, in young age group. During the period from April 1982 to December 1984, we have revised 12 loosened total hip replacement with cementless type. Average follow up was 1 year and 7 months. The age range of the patients was 23 to 64. The results are very promising without any evidence of loosening in all cases.