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Biomedical subjects

R Darmana

Publications and source records attributed to R Darmana.

7 recordsLinked to original sources
PubMed1991

Development of a three-dimensional finite element model of a human tibia using experimental modal analysis.

The modal analysis of a human tibia consisted of characterizing its dynamic behavior by determining natural frequency, damping ratio and mode shapes. Two methods were used to perform the modal analysis: (1) a finite element method (structural model); (2) an experimental modal analysis (modal model). The experimental modal model was used to optimize the structural model. After optimization, differences in results between the two models were found to be due only to mechanical properties and mass distribution. The influences of boundary conditions and geometric properties (such as inertia and length) were eliminated by the finite element model itself. The percent relative error between the two methods was approximately 3%, corresponding to the standard deviation of the measured frequencies. For the frequency range considered, the mode shapes were bending modes in two different vibration planes (latero-medial and sagittal), with a slight torsion effect due to the twisted geometry of the tibia.

Biomechanical Phenomena↗
PubMed1991

Bone cutting.

Bone cutting has always been a problem for surgeons because bone is a hard living material, and many osteotomes are still very crude tools. Technical improvement of these surgical tools has first been their motorization. Studies of the bone cutting process have indicated better features for conventional tools. Several non-conventional osteotomes, particularly ultrasonic osteotomes are described. Some studies on the possible use of lasers for bone cutting are also reported. Use of a pressurised water jet is also briefly examined. Despite their advantages, non-conventional tools still require improvement if they are to be used by surgeons.

Bone and Bones↗
PubMed1991

[Anterior displacement of the tibial tuberosity. An experimental biomechanical study of its effects on the femoro-patellar joint].

The anterior displacement of the tibial condyle was proposed as early as 1963 by P. Maquet as a therapeutic solution to treat femoropatellar arthritis. However, the benefits of such a procedure remain controversial. In this work, the effects of a 1. cm anterior displacement of the tibial condyle, with and without section of the patellar wings, have been studied on the knees of fresh corpses without osteoarthritis. The knees were tested in flexion from 10 to 70 degrees. The study dealt with the contact surfaces, pressures, and femoropatellar forces, which were analyzed with an original and efficient measurement system, with the Fuji Prescale Film as a sensor. This study showed that the femoropatellar contact has not been significantly modified by the displacement of the tibial condyle. We have noted only a slight decrease in the pressure after this type of surgery. These results are in contradiction with Marquet's results. In all cases, the anterior displacement of the tibial condyle with resection of both patellar wings produced the best results. These results suggest that displacing the tibial condyle anteriorly does not have the expected effects. The indication of such a surgical procedure must therefore be established only cautiously and after ruling out other therapeutic methods.

Adult↗
PubMed1989

[Experimental biomechanical study of the advancement of tibial tuberosity].

In 1963 P. Maquet suggested tibial tuberosity advancement as a therapeutic solution for patellofemoral arthrosis, but the fiability of the operation remains controversial. An advancement of the tibial tuberosity by 1.5 centimeter, with and without bilateral retinacular release, was performed on non arthrosic knees of fresh cadavers and on knees presenting medial, lateral or bipolar patellofemoral arthrosis. The joints were tested with flexion ranging from 10 to 70 degrees. The study concentrated on contact areas, pressures and patellofemoral forces analysis using an original and efficient measuring system. The pressure sensitive film used was the Fuji Prescale Film. The study showed that, on non arthrosic knees, the patellofemoral contact was not modified to any significant extent by advancing the tibial tuberosity. In cases of bipolar patellofemoral arthrosis reduced pressures were noted. On the lateral patellofemoral arthrosis experimental model, the tibial tuberosity advancement was efficient as it allowed a 50 per cent reduction in pressure at 10 to 30 degrees of flexion and a 20 per cent reduction at 40 to 50 degrees of flexion and a 20 per cent reduction at 40 to 50 degrees of flexion. In all cases, the best results were obtained from tibial tuberosity advancement associated with bilateral retinacular release. These results indicate that tibial tuberosity advancement may have beneficial effects in cases of lateral and bipolar patellofemoral arthrosis.

Adult↗