Comparison of femoral and tibial pullout forces in bone-patellar tendon-bone anterior cruciate ligament reconstructions with a new interference fixation device.

Interference screws have become the standard method for fixing bone-patellar tendon-bone (BPTB) grafts. To avoid the inherent pitfalls and complications of interference screws, a 28-mm long and from 5 to 7 mm spreadable metal bolt with nontapping threads was developed for this study. The technical applicability and biomechanical characteristics of this new BPTB interference fixation device were investigated by dissection or tensile testing of 48 cadaveric knee specimens from young donors.

Load sharing in augmented anterior cruciate ligament repair: a mathematical analysis based on in vitro measurements.

OBJECTIVE: To quantify the stress on a reinserted anterior cruciate ligament (ACL) we studied the load sharing between the ACL and a 3.7 mm polyethylene terephthalate (PET) band in 10 knees of fresh human cadavers. DESIGN: The load sharing between the Marshall sutures-ACL complex and the PET band and between the ACL and the PET band was calculated by means of a mathematical model.

[Alloplastic augmented femoral reinserted anterior cruciate liganent. Value of 2 channel augmentation for postoperative rehabilitation].

The rupture of the anterior cruciate ligament (ACL) near its femoral origin is a common injury of the knee and can lead to lesions of the meniscus due to instability and to early gonarthrosis. One procedure applied in current orthopaedic practice to prevent such impairment of knee joint function is ACL repair reinforced with a synthetic intraarticular ligament. In this study we used twelve knees of cadavers and after sectioning the ACL in each repaired it according the Marshall technique with USP 1 PDS II sutures.

Comparison of the mechanical performance of three types of unilateral, dynamizable external fixators. An experimental study.

Due to the increasing popularity of unilateral dynamizable external fixators for treating tibial shaft fractures, many new devices are being introduced onto the market. Especially in such half-frame fixators, the choice of any particular device depends above all on the stability of its construction. This study compares the biomechanical stability of three systems tested in axial compression, torsion, and both anterior-posterior and medial-lateral bending.

[Blood pressure-dependent, process-controlled hemostasis to minimize tourniquet syndrome].

The usual limitation of the pneumatic blood arrest period to 1.5 hours is a protective measure in order to prevent permanent injuries due to tissular hypoxia and local pressure. The generally applied cuff pressure of 300 mm Hg for the upper and 500 mm Hg for the lower extremity is an arbitrary value which has been obtained by empiric research and is completely lacking in scientific foundation.

How to increase the stability of external fixation units. Mechanical tests and theoretical studies.

From general physical laws simple formulae have been deduced from which the rigidity of an external fixation unit mounted in different ways becomes mathematically calculable. Furthermore, the stability of various mounting systems under bending forces was investigated experimentally. Particular attention was paid to details of operating technique which are of special importance to the stability of the whole construction.

Experimental tests concerning the biomechanical behaviour of pertrochanteric osteosyntheses.

The biomechanical behaviour of pertrochanteric fractures stabilized by means of an angled plate or flexible condylar nails was characterized by mechanical testing. The stability and the types of motion occurring under dynamic load in the vicinity of the fracture and the effect on the implant were examined. The mechanical test results corroborated clinical experiences.

[Behaviour of pertrochanteric fractures of the femur after condylar nailing under dynamical stress (author's transl)].

In continuation of our studies on dynamic tolerance after condylar nailing in pertrochanteric fractures, we have examined the femora of patients who died within the first 2 weeks after surgery and studied their stress tolerance. We appreciated the lack of the weight bearing medial cortical bone and the need for abduction at the fracture site by the behaviour under stress. The results under stress could be compared with an experimental fracture model.

[Stress tolerance of different osteosynthetic procedures in pertrochanteric fractures (author's transl)].

To obtain valid information on stress tolerance of pertrochanteric fractures, we exposed three different methods of osteosyntheses to dynamical stress and the results were compared. The methods of osteosyntheses were application of a 130 degrees angle plate, performing an adjoining osteosynthesis with bone cement or using cephalocondylar nails. The measurements in connection with photographical and roentgenological examinations of osteosyntheses under stress gave the following results: Compared with the other methods treatment with condylar nails gave equal results in static behaviour yet was clearly superior in its dynamic reaction.