H. K. L. Nielsen

EXPERIMENTAL MENISCAL LESIONS RECONSTRUCTED WITH A CARBON FIBER-POLYURETHANE-POLY(L-LACTIDE) GRAFT

Reconstructive procedures were investigated in meniscal lesions in 14 dogs. Large wedge-shaped lesions were repaired with a graft containing carbon fibers and an organic polymer, prepared from physical mixtures of poly(L-lactide) and a segmented polyurethane. Four and eight weeks postoperation, arthroscopy was performed and the implants were excised. In ten dogs, the reconstructed area appeared to be invaded almost completely by fibrous tissue and, occasionally, by repair-simulating hyaline cartilage. There were no signs of infection.

REPAIR OF THE MENISCUS - AN EXPERIMENTAL INVESTIGATION IN RABBITS

The healing process of wedge-shaped and longitudinal lesions in the meniscus of the knee was investigated in 74 menisci in 24 Chinchilla rabbits. In four cases the whole meniscus was removed and reimplanted. healing was most evident in the wedge-shaped lesions, which were repaired by fibrocartilage. In longitudinal lesions the repair was markedly avascular and consisted of fibrous tissue only. Suturing did not facilitate the healing process.

AN EXPERIMENTAL-STUDY OF RECONSTRUCTIVE PROCEDURES IN LESIONS OF THE MENISCUS - USE OF SYNOVIAL FLAPS AND CARBON-FIBER IMPLANTS FOR ARTIFICIALLY MADE LESIONS IN THE MENISCUS OF THE RABBIT

Reconstructive procedures were investigated in meniscal lesions in 25 rabbits. Large meniscal defects were repaired with either a synovial flap or a carbon fiber implant. Fibrous tissue healing with occasional areas of fibrocartilage occurred after both types of reconstruction. When carbon fibers were used the ingrowing fibroblasts showed directional orientation.

Pigmented villonodular synovitis

SummaryPigmented villonodular synovitis is a benign disease of the synovial membrane of joints, tendon sheaths, or bursae, which nevertheless can cause marked local destruction. Its diagnosis is often delayed because complaints and symptoms are nonspecific. Familiarity with the disease may ensure an earlier diagnosis and consequently early onset of therapy, which may prevent serious damage. This paper describes 18 patients suffering from localized or diffuse pigmented villonodular synovitis. Findings possibly suggestive of pigmented villonodular synovitis include hemarthrosis, soft tissue swelling, radiological evidence of cyst formation at a distance from the weight-bearing area of a joint, an increased triglyceride concentration, and a positive bone scan. A normal appearance on arthroscopy does not rule out the disease. Therapeutic results are better in the localized than in the diffuse form of the disease.

Design of a Lengthening Element for a Modular Femur Endoprosthetic System

A malignant tumour may develop around the knee joint of a child. In the majority of cases it will then be necessary to resect the involved bone with adjacent tissue. A joint team of Groningen University Hospital and University of Twente is currently working on the project of developing a modular endoprosthetic system to bridge the defect resulting from the resection. Since the other, normal, leg continues to grow, the endoprosthetic system will have to include an element the length of which can be adjusted non-invasively. The main conditions to be met by the lengthening element are non-invasive continuous adjustability and a maximum total lengthening of 114 mm. This was achieved by using an external magnetic field. Animal experiments showed that the lengthening element worked well, although moisture infiltrated the telescopic tubes and the lengthening element was covered by proliferating bone at an early stage. Also, the necessary magnetic field proved to be larger than calculated. In a revised design, these problems are resolved. In vitro tests show that the new lengthening element meets all requirements.

An extendable modular endoprosthetic system for bone tumour management in the leg

A modular endoprosthetic system has been developed at the Groningen University Hospital and the University of Twente. The system can bridge a defect resulting from the resection of a malignant bone tumour which has developed around the knee joint of a child. Since the other healthy leg continues to grow, the system includes an element whose length can be adjusted non-invasively by using an external magnetic field. In addition to this lengthening element, there are one hip and two knee components, connectors of various lengths, and fixation elements. The paper describes the elements of the modular endoprosthetic system. Tables are created by means of which the elemental composition of such an endoprosthesis can be determined for each individual patient.

A critique of techniques for reconstruction after internal hemipelvectomy for osteosarcoma

Osteosarcoma may affect any bone but is mainly encountered in long bones like the femur and is rarely observed in flat bones [1]. According to Schajowicz

Design of a Load Cell for the Wagner Distractor

A leg length inequality can be treated by using a Wagner distractor. With this apparatus, it is possible to extend the upper or lower leg slowly. By analysing the measurements of the axial force acting on the femur or tibia the treatment can be optimized and soft tissue damage prevented. To measure the axial force, a load cell has been designed and constructed. This load cell is built into a Wagner distractor and connected with a specially designed measuring amplifier. The load cell and amplifier do not interfere with the lengthening procedure. They are safe for the patient and have an acceptable error of 7 per cent.

BILATERAL TOTAL HIP AND KNEE REPLACEMENT IN RHEUMATOID-ARTHRITIS PATIENTS

SummaryBetween 1978 and 1983, 14 patients suffering from rheumatoid arthritis were treated by bilateral total hip and knee replacement. At the time of this follow-up study (32–92 months postoperatively) one patient had died of concomitant disease and was excluded. The postoperative results regarding pain relief, improvement in performing daily activities, and function were studied in the remaining 13 patients. A 200-point rating scale was used, which compared the pre- and postoperative findings at follow-up. All patients showed marked relief from pain, good function and a good functional score. Although walking ability did not always improve, all patients were enthusiastic.

In Vitro and In Vivo Experiments of a Lengthening Element for a Modular Femur Endoprosthetic System

Malignant bone tumors often are encountered in the femur and in the knee area of children. When treated by adjuvant chemotherapy and local resection of the involved bone and adjacent tissue, the resected bone and joint can be replaced by an endoprosthesis [2]. A disadvantageous consequence of this treatment is that the other, normal leg grows much more than the resected leg. For this reason, a joint team from Groningen University Hospital and the University of Twente embarked upon a project to develop a femur endoprosthetic system that includes an element of adjustable length to match the growth of the other leg.