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The poly-L/D-lactide 96/4 joint scaffolds are used to engineer fibrous tissue joints in situ for the reconstruction of metacarpophalangeal joints. In this experimental study, a supplementary elastomeric stem made of Polyactive 1000PEO70PBT30 (a segmented block copolymer of polyethylene oxide and polybutylene terephtalate with 70/30 PEO/PBT ratio) was used to anchor the joint scaffold in the arthroplasty space. Eleven resected fifth metacarpophalangeal joints of minipig were reconstructed and evaluated radiologically and histologically for 3 years. Plain joint scaffold and Swanson silicone implant arthroplasties (11 of each) in metacarpophalangeal joints of minipig served as controls. Altogether fore limbs of eighteen minipigs were operated for the study. Deleterious tissue reaction with dramatic signs of osteolysis and inflammatory foreign-body reaction was observed around the Polyactive stems. The mean maximum diameter of the osteolytic stem cavity was statistically wider when compared to the mean maximum diameter of Swanson implant group during the first postoperative year. Numerous osteoclasts were found at the margins of the osteolytic areas. No direct bone contact could be seen. At 1 year osteoblastic regeneration and formation of new trabecular bone followed. Finally the foreign-body reaction settled, but the adjoining bones were at this stage highly sclerotic and composed of coarse trabeculae. In contrary to previous in vivo studies suggesting biocompatibility, osteoconductivity and capability to bond to bone, Polyactive 1000PEO70PBT30 stem in this setting caused massive osteolytic lesions and foreign-body reactions.

Biodegradable poly-L/D-lactide (P(L/D)LA) 96/4 joint scaffold arthroplasty is a recently clinically introduced concept in the reconstruction of small joints, however its histology and function in vivo is unknown. In this experimental study on 11 minipigs the fifth metacarpophalangeal joints were reconstructed using a P(L/D)LA 96/4 joint scaffold or Swanson silicone implant. They were evaluated until 3 years. The P(L/D)LA 96/4 joint scaffold formed a porous interposition spacer, which maintained the arthroplasty space and induced fibrous tissue in-growth in situ. No differences were found in the range of motion or arthroplasty space width between the study groups. The P(L/D)LA 96/4 joint scaffold was initially filled with vascular, loose connective tissue. Along with degradation of the scaffold, the in-grown connective tissue matured and condensed turning into dense fibrous connective tissue. After 3 years, the P(L/D)LA 96/4 joint scaffold had almost completely degraded and been replaced by dense fibrous connective tissue. These findings indicate that P(L/D)LA 96/4 joint scaffold arthroplasty leads to the formation of a functional fibrous joint. The avoidance of permanent foreign material makes the biodegradable joint scaffold an attractive alternative for small joint arthroplasty.

Swanson silicone implant is the "gold standard" of metacarpophalangeal joint reconstruction in rheumatoid arthritis (RA) patients. However, durability problems of silicone implants have led us to develop a new technique based on bioreconstructive implants. PLA96 (poly-L,D-lactide copolymer, L:D ratio of 96:4) scaffolds were engineered. Bioabsorption and substitution of porous PLA96 scaffold with living tissue eventually produce a neojoint. In the current prospective study, 23 RA patients (80 joints) were operated on, using PLA96 implants. Fifteen patients (54 joints) have been monitored for at least 1 year. Pain alleviation was well achieved. Range of motion improvement was emphasized to extension direction of functional arc. The average ulnar deviation was preoperatively 26 degrees, and at follow-up it was 6 degrees. Volar subluxation was noticeable in 56% of joints preoperatively and in 6% at 1-year follow-up. This is the first report of the formation of a living, functional joint in situ by means of a synthetic bioreconstructive joint scaffold. Results of this preliminary short-term study are comparable with previously published data on silicone arthroplasty. However, bioreconstructive prostheses can aid in preventing problems that occur with biostable prostheses. Tissue engineering has created a new era in the reconstruction of damaged joints.

76 consecutive Charnley low friction hip arthroplasties were performed in 54 (37 men) patients with ankylosing spondylitis from 1971 to 1991 in the Rheumatism Foundation Hospital. Their mean age was 40 (16-67) years. They were followed until the end of 1999. The overall prosthesis survival was 80% at 10 years, 66% at 15 years and 62% at 20 years. The survival of the acetabular component was 91%, 77% and 73% at 10, 15 and 20 years and that of the femoral component 82%, 79% and 77%, respectively. We found no significant risk factor that predicted prosthesis survival.

The survivorship of 1,553 consecutive Charnley low-friction arthroplasties (LFA) in 1,086 patients with rheumatoid arthritis (RA) were analyzed. There were 846 women (1,236 hips) and 240 men (317 hips), with a mean age of 53.1 years (range, 24-77 years; standard deviation, 10.7). A uniform postoperative regimen with protected weight bearing for 2 months (6 months in patients with bone grafting on the acetabular side) was used throughout the whole study. The overall survival with revision as the endpoint was 90.5% (95% confidence interval [CI], 88.7-92.2) at 10 years and 83% (95% CI, 80.3-85.7) at 15 years. The survival of the femoral component was 93.2% (95% CI, 91.8-96.7) and 89.9% (95% CI, 88.0-93.0) at 10 and 15 years, and survival of the acetabulum was 93.6% (95% CI, 92.1-95.1) and 87.1% (95% CI, 84.6-89.5) at 10 and 15 years. The indication for revision was late deep infection in 19 patients (1.2%) and in others aseptic loosening of prosthetic components. Young age, male sex, and secondary reactive amyloidosis impaired significantly the survival of LFA in the RA patients. In all, cemented LFA provided good results, and it can be justified for the treatment of hip destruction in RA.

The first metatarsophalangeal joint was arthrodesed in 39 patients with rheumatoid arthritis. Fixation material was either biodegradable self-reinforced poly-L-lactide rods or Kirschner-wires. There were 3 clinical nonunions in the biodegradable group, and none in the K-wire group, and radiographic nonunion in 5 and 2 cases, respectively. The fixator had to be removed in 3 cases in the K-wire group. The biodegradable rods did not seem to be any better than K-wires.

A number of industrial processes require the addition of materials to the fermentation broth that are hazardous to health and environment. Agitation of broths inoculated with microorganisms can potentially release aerosols large enough to carry the microorganisms. The influence of agitation, air flow, and bacterial growth on aerosol size distribution, air flow, and bacterial growth on aerosol size distribution was investigated in an industrial pilot scale fermentor. A decrease in particle concentration was observed with increase in bacterial growth; this change was more pronounced in the size range above 2 microm. The aerosol size distribution was found to be practically independent of air flow rate and agitation rate for sizes less than 2 microm. However, for particles larger than 2 microm, the concentration was found to increase with an increase in air flow rate and agitation rate.

A consecutive clinical series of 33 patients with either an undisplaced (Garden I) or minimally displaced (Garden II) femoral neck fracture was randomly divided into two operative protocols. Half of the fractures were treated with three cannulated cancellous bone screws, while the other half were treated with a standard screw-angle plate device. After a mean follow-up of 2 years, 4 patients had died, while 20 of the remaining 29 hips showed excellent or good, 3 fair and 6 poor functional results. The three-screw fixation seemed to yield more technical complications as compared to the screw-angle plate fixation. However, the differences in functional end-results were of no clear statistical significance. We conclude that the screw-angle plate device gives acceptable results in this group of fractures. The use of cannulated hip screws may be more advantageous in the treatment of dislocated femoral neck fractures, where the torsional strength of fracture fixation and femoral head viability are more critical.

In the present work the effect of an HEPA filter and an electrostatic precipitator on the behaviour of Rn decay products has been studied in laboratory conditions. Both filters were found to decrease the equilibrium factor of progeny and increase the unattached fraction of decay products. In a clean air they also decreased the activity of unattached progeny. An electrostatic precipitator was found to produce condensation nuclei which were observable when no other particle sources were present. The ozone produced by the corona discharge of the filter probably has a great effect on the production of these submicron particles. The impurities of the air were found to grow the particles and thus their influence on the behaviour of Rn decay products became in some cases significant.

The effect of the ionization of the air on the decay of bacterial aerosols was studied in a Burns and Plastic Surgery Unit. Ions were generated by free corona needles. The air content of bacteria measured by settle plates was found to be smaller during the ionization period than during the controls period. The number of individual phage typed Staph. aureus strains was especially found to be lower during ionization. The opposite potential increased the disappearance of bacteria from the air. The size of skin particles carrying bacteria is not optimum, but the results obtained show that the ionization may have applications in controlling airborne infection.

Investigations have been made to determine the relationship between indoor radon concentrations and ventilation rates and to find the sources for radon in different rooms. The results show that the radon concentration can be estimated by a simple mathematic model in the case of periodical ventilation. The results of measurements carried out in office rooms demonstrate that soil is the main source for indoor radon. The possibility to use radon for the determination of ventilation rates is discussed.