A method for bone-cement interface thermometry. An in vitro comparison between low temperature curing cement Palavit, and Surgical Simplex P.

Previous temperature measurements at the bone-cement intreface have all shown large variations. To evaluate more precisely the temperature profiles during cement curing, a new experimental model was developed. Eight thermocouple electrodes at the bone-cement interface for each test specimen were used for continuous temperature recordings. Temperature profiles of Palavit was compared with those of Surgical Simplex P in an in vitro model using isolated pig femurs. Defects of 12 x 17 mm in the femoral metaphysis were filled with cement. In six tests with each type of cement, Palavit peaked at a temperature of 50 +/- 0.5 degrees C, whereas Surgical Simplex P peaked at 60 +/- 0.7 degrees C. Core temperatures reached peak values of 70 +/- 0.8 degrees C and 95 +/- 2.2 degrees C for Palavit and Surgical Simplex P, respectively.

The Charnley total hip arthroplasty in juvenile rheumatoid arthritis patients.

A follow up of 27 consecutive total hip arthroplasties in 16 patients with juvenile rheumatoid arthritis was performed. The mean age at surgery was 18 years, and the average follow-up period was 64 months. No serious early complications were recorded, but three deep infections developed from 6 to 18 months after the arthroplasty, all requiring revision. The clinical results were good at follow up, as 20 hips were free of pain and 7 had only slight pain. Most of the patients had improved their walking ability and the range of motion in the hip as well. A poor correlation was, however, shown between the clinical and the roentgenographical results, as there was one femoral implant that was definitely loose and four more hips that had components which were probably loose. The frequency of infections might have been reduced by using antibiotic prophylaxis during surgery in all the cases; the frequency of aseptic loosening might also have been reduced by improved cementing techniques. Because of high loosening rate without clinical symptoms, it is recommended to follow the patients roentgenographically to make revision surgery possible while the bone stock still is sufficient.

Salvage of exposed implants.

With increased use of tissue-expanders the incidence of exposed implants is expected to rise. Eight cases with salvage of an exposed implant are presented. At repair great care was taken to prevent tension on the suture lines either by reducing the volume of the implant or by using a skin flap. Seven patients healed without further complications. In one patient the implant had to be removed due to reexposure. We find that salvage of implants should be tried in suitable cases. If this procedure is not successful a traditional surgical procedure with removal of the implant only has to be delayed for a short time.

Growth disturbances in experimental juvenile arthritis of the dog knee.

In the study of pathophysiological mechanisms in growth abnormalities of the juvenile knee in arthritis an animal model in dogs was developed. Arthritis was induced by intra-articular injections of Carrageenan. Prominent growth changes were enlargement of the distal femoral epiphysis, patellar squaring and decreased endochondral and appositional growth of the distal femur. Generalized osteoporosis of the arthritic limb was present. The induced growth disturbances bear resemblance to the growth abnormalities in juvenile chronic arthritis and hemophilic arthropathy of the knee.

Hemodynamics of the juvenile dog knee in relation to increased venous outlet resistance.

Tissue blood flow was measured by the tracer microsphere technique in the juxta-articular bones of the immature knee, knee joint capsule and skeletal muscles of the hind limbs after unilateral bone cannulation of the distal femoral epiphysis, surgical exploration of the popliteal vessels and unilateral isolated increase of venous outlet resistance in the distal femoral epiphysis during Halothane anaesthesia. Pressure registration was performed in a liquid-filled electromanometric pressure recording system. Significant regional differences in bone blood flow was found within the different bone compartments of both control and test limb. Bone cannulation resulted in insignificant hyperaemia in the distal femoral epiphysis. No changes of distribution pattern of bone blood flow followed the surgical procedure. Ligation of the medial genicular vein caused a three fold increase of venous outlet resistance measured after 5 min, while an insignificant decrease of arterial inlet resistance was calculated. After one hour a significant decrease of both arterial inlet resistance and venous outlet resistance was found. In addition evidence of a veno-arterial reflex mechanism causing a significant unilateral decrease of distal skeletal muscle blood flow was found. The results demonstrate the presence of both venous and arterial regulation, predominantly metabolic, of bone blood flow in the knee.

Relationship between intraosseous pressures and intra-articular pressure in arthritis of the knee. An experimental study in immature dogs.

The influence of chronic synovial inflammation and effusion on the juxta-articular bone haemodynamics in the juvenile knee was studied in 12 immature dogs with Carragheenin-induced unilateral arthritis. Using a fluid filled electromanometric pressure recording system simultaneous pressure measurements were taken from the distal femoral metaphysis, juxta-articular epiphyses and knee joint cavity in general anaesthesia followed by intraosseous phlebographies. During resting conditions the intraosseous pressure of the distal femoral epiphysis and the intra-articular pressure was significantly elevated. The phlebographies showed increased accumulation of contrast in arthritic femoral epiphyses with decreased contrast clearance rate. During increasing intra-articular pressure an augmented vulnerability of the blood supply of the arthritic femoral epiphyses was demonstrated. The results suggests that joint effusion may play an important role in the bone changes in juvenile degenerative arthritis of the knee.

Intraosseous pressure in the patella in relation to simulated joint effusion and knee position: an experimental study in puppies.

Simultaneous pressure measurements were carried out in the patella, juxtaarticular epiphyses and the knee joint cavity of six mongrel puppies. The mean intraosseous pressure in the patella was 12.2 mmHg, range 8-15 mmHg. An increase in intraarticular pressure in turn caused an increase in the intraosseous pressure of the patella and juxtaarticular epiphyses. The pressure increase in the patella was the most pronounced. During extension of the knee joint, a significant rise in intraosseous pressure of the tibial epiphysis and patella was observed, whereas during flexion femoral epiphyseal pressure and patellar pressure increased significantly. The introduction of moderate intraarticular effusion amplified intraosseous pressure responses during flexion of the knee joint. The intraosseous pressure changes during knee movement could not be explained solely by the corresponding changes in intraarticular pressure. Intraosseous phlebography revealed a venous drainage system largely parallel to the arterial blood supply. The contrast clearance time was decreased during moderate elevation of the intraarticular pressure, suggesting increased bone blood flow of the patella.