Partio Ek

Clinical biocompatibility and degradation of polylevolactide screws in the ankle.

The clinical biocompatibility and degradation behavior of absorbable fracture fixation devices are still incompletely known in humans. Fifty-one patients with displaced fracture of the ankle treated by open reduction and internal fixation with absorbable screws made of polylevolactide were seen in followup for at least 3 years. The mean duration of followup time was 52 months. The tissue tolerance and degradation of the devices were studied clinically and radiographically using computed tomographic scans. In addition, biopsy specimens for histologic examination were taken in 5 patients. The screws were clinically effective: An accurate position of the fragments was maintained until union in 50 patients. A mild transient subcutaneous late foreign body reaction occurred in 1 patient 22 months after fixation of the fracture. Despite radiographic evidence of an advancing degradation of the implants, biopsy specimens taken 45 months after the original operation still showed consistent areas of polylactide in the tissues. In 3 patients, a disturbing palpable subcutaneous screw head had to be removed. The incidence of foreign body reactions to polylevolactide screws in the ankle seems to be low, but the duration of the degradation process of the polymer in human tissues is considerably longer than has been anticipated.

Osteochondritis dissecans of the knee fixed with biodegradable self-reinforced polyglycolide and polylactide rods in 24 patients

Summary. 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.Résumé. De 1987 à 1994 vingt-quatre malades présentant une ostéochondrite du genou ont été traités au moyen de broches résorbables, polymères autorenforcés de polyglycolides et polylactides. Parmi celles-ci il y avait 23 ostéochondrites du condyle interne et une du condyle externe. Les broches utilisées pour la fixation de la fracture étaient de 1,1 mm, 1,5 mm et 2 mm. L’âge moyen était de 25 ans (de 16 à 48 ans). La durée moyenne de contrôle postopétoire a été 3,3 ans (de 1 à 7,6 ans). Dans 6 cas lésion était sans déplacement, dans 3 une séparation précoce, dans 11 un détachement partiel et dans 4 cas une libération complète ont été observés. Les broches de SR-PGA (autorenforcé, polyglycolide) ont été utilisés dans 12 cas, celles en SR-PLLA (autorenforcé, polyglycolide) dans 11 cas, et ensemble dans 1 cas. La fixation a toujours été faite dans l’os sous-chondral, et 9 fois par arthroscopie. Les résultats de l’évaluation clinique post-opératoire ont été considérés comme excellent chez 13, bon chez 6, satisfaisant chez 1 et mauvais chez 4 malades. La consolidation radiologique a été obténue chez 19 malades. Il y a eut une synovite parmi les 13 patients du groupe SR-PGA qui a persisté jusqu’à 6 mois après l’opération exigeant un traitement par ponctions. Dans l’évaluation clinique à quatre ans et deux mois, le genou ètait asymptomatique. Les broches de polymères autorenforcés de polyglycolides et polylactides peuvent être utilisés comme un matériau fiable dans la fixation des ostéochondrites du genou.

The tissue-implant interface during degradation of absorbable polyglycolide fracture fixation screws in the rabbit femur.

A transverse transcondylar osteotomy of the distal femur was fixed with an axially placed absorbable fracture fixation screw made of polyglycolide (PGA) in 25 rabbits. Changes at the tissue-implant interface accompanying degradation of the screw were examined histologically, histomorphometrically, and microradiographically seven, 20, 40, 80, and 250 days after implantation. At seven days postimplantation, a layer of fibroblasts was seen surrounding the implant, and new bone formation was discernible in the host tissues adjacent to this membranous structure. At 20 days postimplantation, the geometry of the screw was still intact and the tissue-implant boundary was distinct. The first signs of invasion of vascular granulation tissue into the implant were observed 40 days after implantation, at which time the osteotomies were united. The apparent walling-off response by formation of new trabecular bone outlining the PGA profile continued, with the greatest mean trabecular bone volume fraction at the interface, 23.9%, measured at 40 days. A significant decrease in the new bone volume occurred between 40 and 80 days postimplantation. The intensity of the foreign-body reaction seen was histologically moderate. The giant cell count was highest at 80 days postimplantation, when the migratory activity of phagocytic cells had transported intracellular particulate polymeric debris 400-800 microns away from the original tissue-implant boundary. At 250 days postimplantation, no birefringent polymeric material could be seen in the specimens. No contraindications for the clinical application of PGA implants emerged in this study.

Metallic or absorbable implants for ankle fractures: a comparative study of infections in 3,111 cases.

Absorbable fracture fixation has been in clinical use since 1984. Our study compares the infection rates and some infection parameters between metallic (2073 patients) and absorbable fracture fixation devices (1012 patients) in displaced ankle fractures. The infection rate associated with metallic fixation was 4.1%, compared with 3.2% absorbable fixation (p 0.3). The patients who had a wound infection were older when metallic fixation was used (p 0.01). They also had a bi- or trimalleolar fracture more often than did patients treated with absorbable fracture fixation, but this difference did not have a significant effect on the wound infection rate (p 0.2). The infections were mostly caused by microorganisms of the Staphylococcus species. Deep infections were equally common with both fixation methods (0.4%), but there was some variation in the bacterial spectrum.

Talocrural arthrodesis with absorbable screws 12 cases followed for 1 year

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.

Bioabsorbable implants in orthopaedics

Bioabsorbable devices are the best alternative to metals for the internal fixation of fractures, osteotomies, arthrodeses, and ligament injuries because, during the healing process, bioabsorbable devices maintain the fixation, decompose gradually, and the stresses are transferred gradually to the healing tissue so that no stress shielding will occur. Bioabsorbale surgical devices do not require a removal operation, and so may reduce the total cost when compared to metallic devices. This review deals with the bioabsorbable synthetic polyglycolide (PGA), polyactide (PLA), and polydioxanone (PDS) polymeric devices in skeletal fixation, based mainly on our own investigations and experience, in over 3000 operations since 1985.1

Long-term results of ankle and triple arthrodeses fixed with self-reinforced polylevolactic acid implants in patients with rheumatoid arthritis

Self-reinforcing polylevolactic acid (SR-PLLA) implants have been used in arthrodeses of patients with rheumatoid arthritis. No long-term evaluation has been published so far. Two patients (three ankles) with destruction of the ankle joint and seven with destruction of the subtalar joint received ten arthrodeses. One out of three ankle arthrodeses healed and nonunion developed in two. Five out of seven triple arthrodeses attained bony union. Two patients with malunion of the subtalar and talonavicular joints are free of symptoms and need no reoperation. One superficial wound infection healed by oral antibiotics. In one patient, an ankle arthrodesis was performed 6 years after the triple arthrodesis of the left foot. SR-PLLA implants can be used in triple arthrodesis in rheumatoid arthritic patients with good results comparable to those of other studies. The problems with nonunion of ankle arthrodeses noticed in former studies are also attributable to this fixation method.

Redisplacement after ankle osteosynthesis with absorbable implants

Abstract 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.

Totally absorbable fixation in the treatment of fractures of the distal femoral epiphyses

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.

Survival of the Townley knee: 360 cases with 8 (0.1-15) years' follow-up

We evaluated 360 Townley arthroplasties in 167 OA and in 193 RA knees, performed between 1978-1986. 35 revisions were performed during the follow-up time. The main reasons for revision were aseptic loosening (18 knees), instability (6 knees), and infection (5 knees). The durability of different prosthesis components and of different tibial trays in relation to loosening were analyzed separately. The probability of the prosthesis remaining in situ was 94 percent after 5 years and 89 percent after 10 years. The success rate at 10 years was not significantly higher in arthrosis (94 percent) than in rheumatoid arthritis (85 percent). The other patient-related factors, age, sex, weight, did not influence the results. Comparing the different prosthesis components and the different designs of the tibial tray, we found no differences in success rates.