Biomedical subjects
Publications and source records attributed to E Engelbrecht.
The St. Georg total knee prosthesis has been modified to incorporate axial rotation of the tibial component. The kinematics approximate more those of the normal knee and the stress imposed at the bone-cement interface are attenuated, thus reducing the risk of mechanical failure. The construction and laboratory testing are described.
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Eleven patients underwent disarticulation for infected arthroplasty of the hip. Exchange total hip arthroplasty or conversion to a Girdlestone excision arthroplasty had been undertaken previously an average of 2.9 times. The indications for disarticulation were as a life-saving measure, or as a result of severe infection of soft tissue and bone, loss of bone stock, or vascular injury. While the indications for this drastic operation were highly individual, there were instances where disarticulation could have been avoided if repeated exchange operations had been eschewed in deference to a Girdlestone procedure.
Clinical and laboratory investigations have resulted in a new design for the shaft prosthesis of the "St. Georg" model total hip prosthesis, the purpose of which was to minmize the risk of biomechanical complications. The original method of attachment and the same material for the limb were retained for our investigations. It was possible to test the bending strength, the length, and the geometry of the shaft as well as how structure of the bearing surface of the collar influences the force flow within the compound system. The distrubances produced in physiological force flow produced on insertion were also investigated. The results obtained enabled us to design a new shaft prosthesis.
Total shoulder replacement has been successful as treatment for patients with irreparably damaged and painful glenohumeral joints, though improvement of joint motion is limited. Our experiences with 101 alloplastic operations on the human shoulder are reported for further design and construction of total shoulder joint prostheses. The type of prosthesis chosen depends on the degree of joint damage. A dorsal approach is recommended, carefully preserving or restoring function of the musculo-tendinous cuff mechanism.
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In joint replacement surgery an exchange of endoprostheses is technically most difficult, time consuming, and extremely unpleasant for the patient. Removal of the implant without damaging the bone entails many problems. Experience has shown that, in addition to the normal operative technique, the ultrasonic method may be very helpful. Ultrasonic implements that melt thermoplastic implants facilitate the removal of those implants (e.g., polymethylmethacrylate, polyethylene), protect the tissue, and save time. This method is not an alternative to the normal operative technique, but an additional help.
Massive bleeding of the pelvic vessels during an alloarthroplastic operation on the hip joint should be suspected in cases of abnormal anatomic conditions. Therefore, the operative procedure should be meticulously planned including extensive X-ray investigations such as angiography and computer-tomography. Surgical preparation and procedures in case of vascular complications are described. Hints on operative techniques are given to prevent vascular complications during and after surgical intervention of the hip joint.
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Since 1969, we have used 2 different types of knee prostheses to reconstruct arthritic knees. The surface replacement prosthesis (sledge) is indicated where ligamentous stability is present and angular deformity is not severe. In addition, the sledge prosthesis may be implanted with good results in selected acute comminuted tibial plateau fractures. The total hinged prosthesis of metal design is recommended in knees which are severely deformed, and unstable, and therefore not suitable for the sledge prosthesis. Marked relief of pain was the most significant result in our patients. Residual knee pain was most frequently due to patello-femoral pain and, when severe, this was satisfactorily controlled by performing a patellectomy. Motion was usually maintained at the preoperative range or improved, mainly by reducing or eliminating the knee flexion contracture. In a high percentage, the unicompartmental sledge prosthesis has given excellent results. However, we tend to insert a bi-compartmental sledge prosthesis because experience has shown that even slight damage of the articular surfaces of the opposite side is likely to further deteriorate rapidly. Although a significant number of complications occurred, these have been minimized by further conservative and operative treatment. We anticipate a further reduction in complications based on our initial experience, and prosthetic revisions.
Experiences with shoulder replacement in 40 cases since 1966 and the development of a nonblocked total prosthesis are described. The replacement of both joint surfaces according to the principles of low friction arthroplasty ist needed to obtain relief of pain. The nonblocked system corresponds in a high degree to physiologic conditions. The shape of the implant and the meticulous reconstruction of the inner and outer rotator cuffs reduce the danger of dislocation considerably. Only small bone resection is necessary. In cases of dislocated compound fractures and of painful posttraumatic and rheumatic arthrosis, total replacement could be an alternative to resection of the humeral head as well as to shoulder arthrodesis.
Based on twelve cases, this paper reviews the possibilities of partial replacement of the humerus. In 6 cases an interpolation was successfully performed replacing a resected part of the humeral shaft while maintaining the shoulder and elbow joint. The interpolated material is polyethylene, centrally reinforced by metal. A resection of up to 17 cm was performed. The longest period of observation is more than 2 years. This operative procedure is preferred to the methods so far used in cases of extensive destruction of the humeral shaft. Primarily, osteolyses are an indication for this type of operation.
The elbow-prosthesis, design St. George, a hinge prosthesis is developed according to the principle of the Low Friction Arthroplasty. Only small resection of the joint is necessary so that in the "second line of defence" a resection-arthroplasty of elbow is possible. The experiences on 44 implanted prosthesis and the results of 37 cases are described. Restriction of motion, pain, instability and ankylosis in case of rheumatiod arthritis and posttraumatic arthrosis were the main indications.
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