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Biomedical subjects

K Diehl

Publications and source records attributed to K Diehl.

At least 37 records · Page 2Linked to original sources
PubMed1975

[Bone stress and reconstruction of the bone at the alloarthroplasty of the upper end of the femur with cement bonding (author's transl)].

Structure and shape of the upper end of the femur are determined by direction and height according to their strain. Forces which flow from pelvis into femoral head have at first an unfavourable direction that means a non-axial direction of the femoral shaft. The mechanic task of the proximal femur (epi- and metaphysis) is to divert the forces in a way that they disperse in axial direction to the shaft (tension and pressure forces of the upper end of the femur). By replacement of the endoprosthesis, the epiphysis and a large part of the metaphysis is removed and will be replaced by metal- or bone cement. This leads to a thorough change of the mechanical stress. According to Wolff's transformation law the bone tends to adopt the changes stress throught reconstructing processes. Static and morphologic researches of the normal and endoprosthetic femur could demonstrate a conformity of bone reconstruction and changed bone stress. The spongiosa remaining after resection is not sufficient to distribute the influenced forces of the shaft of the bone. Result is a cancellous bone of the upper end of the shaft. We call this reaction "Metaphysierung". According to the unphysiologic high bending stress of the shaft in level of the lower half of the haft of the prosthesis, a hypertrophy of cortex and vault occurs. The large stress of this part of the bone can be the cause of non-infectious late loosenings of the prosthesis.

Biomechanical Phenomena↗
PubMed1975

[Biomechanical investigations of osteosynthesis at metaphys area of tibia and femur with selftensed angle plates (author's transl)].

Straight pressure plates create an eccentric tension force as well as an osteosynthesis with angle pressure plates. Both kinds of plate incline to gape the osteosynthesis and/or fracture gap. Therefore an overbending or additional angle allowance is necessary. In our biomechanical investigations we showed that at average bone stability, an overbending of the angle respectively an additional angle allowance of 3 degrees is most favourable. Uniform distribution of power transmission can be achieved at the entire osteotomie level using large and small angle plates with appropriate plate thickness and plate tension force. Sufficient stability in mobilisation is guaranteed without additional cast fixation.

Biomechanical Phenomena↗
PubMed1975

[Biomechanical tests on osteosynthesis with small-bone plates (author's transl)].

Plating in handsurgery has become a more frequently used method since the special instruments of the Swiss AO and the self-compression plates of Mittelmeier (made by Osteo AG) have been introduced. The results of biomechanical measurements, comparing the interfragmental compression power and tensile strength of the small-fragment-plates of the AO with the crescent-formed plates of Mittelmeier are reported. The compression power of the first reach their maximum by 8 kp, the latter an average of 20 kp. A gapping of the fracture occures under a deflection-momentum of 4 kp - cm using AO-plates and 10 kp - cm using the crescent-formed plates. The bending stiffness under deflection momentum to the off side of the plate is in the crescent plate 10 times higher. Only an angulating bending in the middle gives in both plates an all over good contact to the fragments. Finger osteosyntheses are very rigid against a deflection momentum in the level of the plate. (Regarding that, we fixe the plate sidewise on the bone.) Our conclusion is, that the better biomechanical stability of the self-compression plates--Mittelmeier-plates--is a result of the higher compression powers.

Biomechanical Phenomena↗
PubMed1975

[Internal compression arthrodesis of the ankle joint (with examination of stability for comparison].

A new technique of arthrodesis of the ankle joint by internal fixation with self-compression blade-plates is presented. The both possible techniques of inserting the plate lateraly or medialy are described. We prefer the lateral approach. After resection of the ankle joint we also resect the tibiofibular syndesmosis putting than in a transfixion screw. We than compare under biomechanical aspects the new techniques with Charnley's external fixation with compression clamps. The osteosynthesis with blade-plates gives a higher stability in which external splintage with plaster becomes unnecessary. Following our experiences consolidation occurs after 8 tp 12 weeks.

Ankle Joint↗