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Self-reinforced polylactide-polyglycolide (80/20) composite rods, 2 mm in diameter and 36 mm in length, were implanted into the dorsal subcutaneous tissue of 20 rabbits. Osteotomies of the distal femur were fixed with these rods (2x15 mm) in the rabbits. The follow-up times varied from 3 to 104 weeks. After sacrifice, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, microradiographic, oxytetracycline-fluorescence, and histomorphometrical studies of the osteotomized and intact control femora were performed. After 6 weeks the mechanical properties had decreased significantly, but osteotomies had healed uneventfully. The present investigation showed that the mechanical strength and fixation properties of SR-Polylactide-glycolide (80/20) rods are suitable for fixation of cancellous bone osteotomies in rabbits provided that the operative technique is correct. The present article is the first report on the application of these rods for fixation of cancellous bone osteotomies.

Purpose: Osteosynthesis by means of bioresorbable implants, mostly of self-reinforced poly-L-lactide (SR-PLLA), has been used in humans for about 10 years. The aim of this study was to examine the controversy between histological studies confirming fragmentation of the biomaterial and radiological studies showing no breaking of the material., Material and Methods: Six patients with displaced malleolar fractures operatively treated with biodegradable SR-PLLA screws underwent MR examinations at 1.5 T, immediately postoperatively and after one to two years., Results: The biodegradable osteosynthetic screws were clearly seen on all MR images. Of 12 screws, 6 were broken at the final examination (5 syndesmotic transfixation screws and 1 screw through the growth cartilage)., Conclusion: The breaking of a biodegradable osteosynthesis is possible to document on MR images.

A total of 1202 fractures of the ankle were treated with absorbable implants made of polyglycolide/polylactide copolymer or self-reinforced polyglycolide and/or self-reinforced polylactide between November 5, 1984, and January 12, 1994. A redisplacement after fixation was diagnosed in 30 patients (2.5%). The redisplacement occurred in 8 of 934 (0.9%) simple ankle fractures and in 22 of 268 (8.2%) severer ankle fractures. A breakage or loosening of the absorbable implant was verified at reoperation in 8 cases and was suspected in another 9. A technical failure was the main reason in 13 cases. A reoperation was performed for 25 patients. The absorbable implants seem to provide a secure fixation in the majority of ankle fractures, but the use of these implants showed unsatisfactory results in unstable and comminuted fractures.

Nine adolescent patients with a femoral fracture involving the physeal plate were treated by using self-reinforced absorbable polyglycolide (SR-PGA) and poly-L-lactide (SR-PLLA) screws with a follow-up for an average of 2 years and 2 months. During the follow-up all but one of the femurs became skeletally mature. In two of nine patients a clinically significant growth disturbance occurred. The average length difference of the femurs was -5 mm (ranging from +8 mm(-)-41 mm). One valgus deformity was noted. In four patients a lengthening and in four patients a shortening of the operated femur were registered at the end of follow-up. Open reduction and fixation with absorbable screws seem to be suitable for the fixation of distal femoral fractures in adolescents.

Over a period of 7 years (1987-1994), 24 cases of osteochondritis dissecans of the knee were treated with self-reinforced polyglycolic acid (SR-PGA) and polylactic acid (SR-PLLA) rods. Rods measuring 1.1 mm, 1.5 mm and 2 mm in diameter, and 20-40 mm in length were used in the fixation of the fragment depending on the size of the lesions. There were 23 patients with osteochondritis dessicans in the medial and 1 in the lateral femoral condyle. The average age of the patients was 25 years (range: 16-48). Follow-up was for 3.3 years (range: 1-7.6). There were 6 lesions in situ, 3 early separations, 11 were partially detached, and there were 4 loose bodies. SR-PGA rods were used in 12 patients, SR-PLLA rods in 11 patients, and both SR-PGA and SR-PLLA rods in 1 patient. The rod in each case was inserted subchondrally and in 9 cases arthroscopically, using a special instrument. In our study, the clinical result was excellent in 13 patients, good in 6, fair in 1 and poor in 4. On radiological assessment the fragment had healed in 19 cases. Synovitis occurred in 1 patient in the SR-PGA group (1/13): the effusion continued for 6 months postoperatively but, after treatment by needle aspiration, there were no symptoms at follow-up 4.2 years later. We conclude that SR-PGA and SR-PLLA rods can be used intra-articularly for the adequate fixation of osteochondritis dissecans.

Absorbable fixation devices have been clinically used in the fracture treatment for over ten years. No studies have been published where bone mineral density has been measured after bone consolidation comparing absorbable and metallic fixation. In this study the bone mineral density was measured after operative ankle fracture treatment with absorbable self-reinforced polyglycolic acid (SR-PGA) screws (14 patients) or with absorbable self-reinforced polylactic acid (SR-PLLA) screws (eight patients) compared with metallic fixation (17 patients). The overall results were radiologically good in every group. A statistically significant difference in the bone mineral density (BMD) was found only in the distal tibial metaphysis between SR-PGA screw and metallic fixation. The BMD increased in the distal tibia after SR-PGA screw fixation by an average 18.3%. The average change of BMD in the distal tibia after SR-PLLA screw fixation decreased by 6.4% while after metallic fixation the average change of MBD decreased by 18.6%. Bone mineral density measurements in the present study may indicate osteogenetic capacity of polyglycolide implants in the bone after fracture or osteotomy fixation. On the other hand, metallic implants showed negative effects to the bone.

Biodegradable self-reinforced polyglycolide screws and rods were constructed for internal fixation of fractures in cancellous bone. The self-reinforced texture was achieved by embedding polyglycolide fibres in a polyglycolide matrix. In a prospective clinical study, a total of 37 patients at least 65 years of age with displaced malleolar fractures were managed by open reduction and internal fixation using either biodegradable screws and rods or metallic implants in a randomly allocated series. The results were assessed approximately one year after the fracture. One wound infection occurred after metallic fixation. Reoperation because of displacement of the fracture was needed in one patient after biodegradable fixation. The functional results were satisfactory in most patients. There were no major difference in the end results between both operative methods used.

In 11 patients, 12 arthrodeses of the ankle joint were performed by using absorbable self-reinforced poly-l-lactide (SR-PLLA) or polyglycolide (SR-PGA) screws. 8 patients had posttraumatic arthrosis, 3 rheumatoid arthritis, and 1 rigid flexion contracture of the ankle due to neuropathy. The average follow-up time was 14 (7-22) months. Solid fusion was achieved in 11 of 12 cases in 9(6-16) weeks.

The series consisted of 152 patients with ankle fractures treated between May 1987 and August 1989 using absorbable screws of self-reinforced polyglycolide 3.4 mm in inner diameter and 25-70 mm in length. The mean follow-up time was 2 years, 5 months (range, 1 year, 7 months-3 years, 10 months). After open reduction, a channel was drilled through the fracture surfaces and the fragments were fixed with one absorbable screw or screws. A plaster cast was used postoperatively. At 1-year follow-up observation, the radiographical result was anatomical in 93.3% of 104 patients with unimalleolar and bimalleolar ankle fractures (Weber A or B) and in 80.5% of 41 severe ankle fractures. Seven patients were unavailable for follow-up observation. Two reoperations were performed because of primary or secondary failure of fixation. In all unimalleolar and bimalleolar fractures and in 95.1% of severe ankle fractures the functional recovery score was at least satisfactory. Sinus formation as a sign of tissue reaction was observed in 10 patients 2-6 months postoperatively, but this did not influence the healing of the fracture or the functional recovery. This report is the first extensive publication on the clinical use of absorbable screws.