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[Comparative results of compression and non-compression operation methods following medial femoral neck fracture].

This is a personal clinical and radiological follow-up of 65 patients with fractures of the femoral neck who were treated in 1973 to 1984 at our hospital. 30 patients were operated by nailing according to Smith-Petersen and in 35 patients osteosynthesis was performed by means of three or four lag screws. A comparative study between these two methods was done. The two main complications of femoral neck fracture, a vascular head necrosis and pseudarthrosis, were of special interest. The mean follow-up time was 7.2 years with the fracture fixed by nailing and 4.1 years, with the fractures operated by lag screws. Out of the 65 patients the total rate of femoral head necroses was 21.5% and 10.7% of pseudarthrosis. In the fractures treated by the nailing method the rate of necrosis was 23.3% and the rate of pseudarthrosis 13.3%. In the fractures operated by lag screws the incidence of head necrosis was 20% and 8.5% by pseudarthrosis. Fracture displacement was primarily responsible for the development of aseptic necrosis, but we could see also a relation between head necrosis and the inclination of the fracture line. Fractures of the type PIII/GIII/IV are those with the highest rate of avascular necrosis. Furthermore, the development of both, aseptic necrosis and pseudarthrosis, is strongly influenced by incomplete reduction.

Adult↗

[Treatment of bilateral distal tibial nonunions. Use of an intramedullary compression nail and a modified locking compression plate osteosynthesis].

Operative treatment of distal tibial fractures remains a challenge for the surgeon even today. The soft tissues demand atraumatic operative techniques, although an anatomical reduction of the articular fracture component is mandatory. The nonunion rate increases with disturbed local blood supply, widened fracture gap, unstable fixation. If a nonunion occurs, an individual treatment concept is required, so that even difficult situations can be successfully managed, as described in our case with bilateral tibial nonunions.

Adult↗

[Biomechanical properties (compressive strength and compressive pressure at break) of hyaline cartilage under axial load].

INTENTION OF THE STUDY: Explanations concerning the physical properties of hyaline cartilage are different. It was the intention of this study to determine the material parameters of hyaline cartilage under axial load (elasticity, plasticity, elasticity and module pressure stress to break). METHODS: Specimens from the medial femoral condyle (chondro-cortical ships) from adult female domestic pigs (n=28) were used for the experiments. The specimens were completely embedded in plaster to minimize shearing. Axial load was carried out by an universal mechanical testing machine (Zwick Z2.5/TS1S, Ulm, Germany) to determine elastic and plastic deformation and pressure stress to break. RESULTS: Axial load up to 5 MPa produces an almost elastic deformation, an increasing axial load results in a plastic deformation. In the range of 3 to 5 MPa the principle of Hooke is valid. The elasticity module amounted to 39.2 +/- 11.9 N/mm(2), determined under 3.8 MPa axial load. An axial load of 25.8 +/- 5.2 MPa (sigma max ) causes a break of cartilage. A strong correlation between break resistance and thickness of the chondral slice (r=0.71; p < 0.05) was observed. CONCLUSIONS: The low module of chondral elasticity characterizes this tissue as "soft". Moderate axial load causes an ideal elastic, higher axial load a plastic deformation. The medium pressure to break to amounted 25.8 MPa. The medium pressure to break of 25.8 MPa is comparable with the forces produced by an unrestrained limited downfall from a height of 4.3 m. It must be concluded that isolated chondral fractures are rare consequences of a trauma as long as accompanying ligamentous or osseous damages are not found.

Animals↗

Bone plate fixation: an evaluation of interface contact area and force of the dynamic compression plate (DCP) and the limited contact-dynamic compression plate (LC-DCP) applied to cadaveric bone.

OBJECTIVES: To determine the effects of bone morphology on the interfacial mechanics of bone plate fixation. DESIGN: A comparison of two bone plate designs using measures of contact area and force in three conditions of bone type. INTERVENTION: The influence of bone plate design, bone type, and implant location on interfacial characteristics of contact area and average force were evaluated using pressure-sensitive film in cadaveric bone. Data were quantitated using computer-assisted image analysis. MAIN OUTCOME MEASUREMENTS: Means of the two dependent variables in each of the three conditions were compared using analysis of variance. RESULTS: In human femora and equine third metacarpi, there were no apparent differences in interface contact area attributed to bone plate design, although there were significant differences for interface contact force. In humeri, significant differences in both interface contact area and force were found between bone plate designs. CONCLUSIONS: Results show that bone surface topography and implant location are major determinants of the interfacial elements of contact area and average force between a plate and the bone to which it is applied.

Animals↗