The muscular system, the connective tissue and the bones are the components of a biomechanical pelvis-lower extremity model. The occasional electrical events in the muscles were not taken into account, as they can only be measured by physiological methods. In this publication, the connective tissue of the lower extremities is examined. The connective tissue system of the thigh and leg was prepared; after removal of the muscles the so-called ‘hollow’ lower extremity could be studied. A topographical documentation followed, and the structure and directions of the fibers were observed with polarized light. The connective tissue systems of the lower extremities and bones form a biomechanical effective and functional system, the bone-fascia-tendon system. The components of the connective tissue in such a system are the fascia lata, the crural fascia, the iliotibial tract, the femoral and crural intermuscular septa, and the membrana interossea. The iliotibial tract is not the sole part of this system having a tension band effect, other components – above all the lateral femoral intermuscular septum – also reduce the forces acting on the bones. Therefore, the tensile strength of the iliotibial tract has to be considered lower as supposed. The iliotibial tract is not a part of the fascia lata; it is an independent, vertically tightened tendon of the ‘pelvic deltoid muscle’ (gluteus maximus, tensor fasciae latae). The iliotibial tract passes over the greater trochanter like on a roller bearing. It is not attached directly to the greater trochanter and to the lateral femoral condyle, so that previous models have to be modified. The iliotibial tract glides in a fascia bag which is composed of oblique and horizontal fibers of the broad fascia. The iliotibial tract, as tendon of the pelvic deltoid muscle, continues in a lateral location into the leg where it is fixed to the lateral malleolus. The present report provides a new description of the structure of the connective tissue system of the lower extremities. The model reported complies with the laws of similarity mechanics by describing exactly the geometric, physical and functional conditions. This representation could facilitate the construction of a computer-aided, efficient, biomechanical model of the pelvis-lower extremity region considering also the complex functional circumstances, in contrast to previous models. In order to construct such a model the data obtained by the examination of the connective tissue of the lower extremities have to be given into a data bank, which, however, has to be built up.

BackgroundNon-union continues to be one of the orthopedist’s greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether “aseptic” tibial non-union can be the result of an unrecognized infection.MethodsA total of 23 patients with non-union following tibial shaft fractures without clinical signs of infection were investigated. Intraoperative biopsy samples obtained from the non-union site were examined by means of routine culture methods and by polymerase chain reaction (PCR) for the detection of 16 S ribosomal RNA (rRNA). Control subjects included 12 patients with tibial shaft fractures.Results23 patients (8 women and 15 men; mean age: 47.4 years) were included into this study. Preoperative C-reactive protein levels (mean: 20.8 mg/l) and WBC counts (mean: 8,359/μl) in the study group were not significantly higher than in the control group. None of the samples of non-union routine cultures yielded microorganism growth. Bacterial isolates were found by conventional culturing methods in only 1 case of an open fracture from the control group. In this case, PCR yielded negative results. 16 S rRNA was detected in tissue specimens from 2 patients (8.7%) with non-union. The analysis of these variable species-specific sequences enabled the identification of specific microorganisms (1x Methylobacterium species, 1x Staphylococcus species). Both PCR-positive patients were culture-negative.ConclusionsThe combination of microbiological culture and broad-range PCR seems to substantially add to the number of microbiological diagnoses obtained and may improve the clinican’s ability to tailor therapy to the individual patient’s needs.

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The sacroiliac ligamentous apparatus was examined as a part of a biomechanical pelvis-lower extremities system. The ligamentous apparatus of two pelves was freed, and the findings concerning the ligaments and their direction were drawn by a modular constructed, three-dimensional calculator model of the pelvic region. The ligamentous apparatus of the sacroiliac joint belongs to a functional system. Its task is to minimize every movement in this amphiarthrosis. The ligamentous apparatus shows an adaption to strong or long-time-acting stresses. The junction between the os sacrum, pelvis and the ligamentous apparatus of the sacroiliac joint can be described as self-tightening. Local stresses are also reduced by the ligaments. A loosening in this system, which has to fix the os sacrum to the pelvic girdle, leads to a static insufficiency. The consequence is pain due to an irritation of the lumbosacral trunk. The exact description of the structure allows a representation according to the laws of similarity mechanics. With such a representation one can build up a computer-aided biomechanical model of the pelvis-lower extremities region. Examples for such a model are biomechanical finite-element models. By observing the laws of similarity mechanics (an exact description of geometric, physical and functional conditions) an efficient biomechanical model can be constructed that also takes into consideration the complex functional circumstances, in contrast to previous models. In order to construct such a model, one has to feed the findings of the examination into a data bank, which has to be demanded.

Although there is a clear trend toward internal fixation for ankle arthrodesis, there is general consensus that external fixation is required for cases of posttraumatic infection. We retrospectively evaluated the technique and clinical long term results of external fixation in a triangular frame for cases of posttraumatic infection of the ankle. From 1993 to 2006 a consecutive series of 155 patients with an infection of the ankle was included in our study. 133 cases of the advanced "Gächter" stage III and IV were treated with arthrodesis. We treated the patients with a two step treatment plan. After radical debridement and sequestrectomy the malleoli and the joint surfaces were resected. An AO fixator was applied with two Steinmann-nails inserted in the tibia and in the calcaneus and the gap was temporary filled with gentamicin beads as the first step. In the second step we performed an autologous bone graft after a period of four weeks. The case notes were evaluated regarding trauma history, medical complaints, further injuries and illnesses, walking and pain status and occupational issues. Mean age at the index procedure was 49.7 years (18-82), 104 patients were male (67,1%). Follow up examination after mean 4.5 years included a standardised questionnaire and a clinical examination including the criteria of the AO-FAS-Score and radiographs. 92,7% of the cases lead to a stable arthrodesis. In 5 patients the arthrodesis was found partly-stable. In six patients (4,5%) the infection was not controllable during the treatment process. These patients had to be treated with a below knee amputation. The mean AOFAS score at follow up was 63,7 (53-92). Overall there is a high degree of remaining disability. The complication rate and the reduced patient comfort reserve this method mainly for infection. Joint salvage is possible in the majority of cases with an earlier stage I and II infection.