Comparison of in vitro hydrolysis, subcutaneous and intramedullary implantation to evaluate the strength retention of absorbable osteosynthesis implants.

To evaluate the behaviour of mechanical properties of absorbable osteosynthesis implants in vivo, the strength retention of self-reinforced polyglycolide rods in distilled water at 37 degrees C in the subcutis and femoral medullary cavity of the rabbit was investigated. The self-reinforced polyglycolide rods lost their strength significantly faster in vivo than in vitro. The strength loss of the self-reinforced polyglycolide rods was only slightly faster in the medullary cavity than in the subcutis. As the removal of the implants from the medullary cavity became difficult 5-6 wk after implantation, it is suggested that subcutaneous implantation would be a suitable method to evaluate the strength retention of absorbable osteosynthesis implants.

Strength retention of self-reinforced polyglycolide membrane: an experimental study.

Self-reinforced polyglycolide (SR-PGA) devices are stronger than non-reinforced ones. To study the strength retention of SR-PGA membrane, in vitro and in vivo, membranes were either immersed in distilled water at 37 degrees C, or implanted in the subcutis or around the femoral bone of rats. The SR-PGA membranes lost their strength in vitro by 6 wk, while they retained it for 15 wk in vivo due to the fibrous tissue that formed around and inside the implant (biomembrane). This is an advantage when clinical application of the membrane is being considered.

Bioabsorbable fixation in orthopaedic surgery and traumatology.

Bioabsorbable internal fixation devices were introduced clinically in the treatment of fractures and osteotomies of the extremities at the Department of Orthopaedics and Traumatology, Helsinki University, in 1984. Since November 5, 1984, a total of 3200 patients were managed using bone or ligament fixation devices made of self-reinforced (matrix and fibres of the same polymer) bioabsorbable alpha-hydroxy polyesters. The devices used included cylindrical rods, screws, tacks, plugs, arrows, and wires. The most common indication for the use of bioabsorbable implants was the displaced malleolar fracture of the ankle. Transphyseal fixation with small-diameter, mainly polyglycolide pins was used in children. The postoperative clinical course was uneventful in more than 90% of the patients. The complications included bacterial wound infection in 4% and failure of fixation in 4%. In one-fifth of the latter cases, however, re-operation was not necessary. The occurrence of non-infectious foreign-body reactions two to three months postoperatively has been observed in 2% of the patients operated in the last few years with polyglycolide implants but none of the patients managed with polylactide implants. This inflammatory tissue response often required aspiration with a needle but did not influence the functional or radiologic result of the treatment. Owing to the biodegradability of these internal fixation devices, implant removal procedures were avoided. This results in financial benefits and psychological advantages. Bioabsorbable implants can also be used in open fractures and infection operations.

The effect of trauma to the lower femoral epiphyseal plate. An experimental study in rabbits.

Forty-four rabbits were operated on when five weeks old; in one group a 2 mm drill-hole was made in the intercondylar portion of the right femur across the central portion of the growth plate up to the diaphysis, while in the other group a similar drill-hole of 3.2 mm was made. At 3, 6, 12 and 24 weeks after operation, specimens from the growth plates of both femora were analysed using radiographic, microradiographic, histological and histomorphometric techniques. It was found that destruction of 7% of the cross-sectional area of the growth plate caused permanent growth disturbance and shortening of the femur.

Biodegradable internal fixation for malleolar fractures. A prospective randomised trial.

Fifty-six patients with displaced malleolar fractures had open reduction and fixation of the fracture fragments using, by random selection, either biodegradable implants or metal AO plates and screws. The cylindrical biodegradable implants were made of polylactide-glycolide copolymer (polyglactin 910). The complications, radiographic results and functional recovery were studied prospectively. After follow-up of at least one year, no significant differences emerged in the complication rate or in the results of treatment between the two methods of fixation. Because of the advantage of avoiding the need to remove metal fixation after union, we now use biodegradable internal fixation routinely to treat displaced malleolar fractures.

Self-reinforced absorbable screws in the fixation of displaced ankle fractures: a prospective clinical study of 152 patients.

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.

Reinsertion of the ruptured ulnar collateral ligament of the metacarpophalangeal joint with an absorbable self-reinforced polylactide tack.

70 patients with total avulsion or rupture of the ulnar collateral ligament of the first metacarpophalangeal joint were treated surgically, using an absorbable self-reinforced poly-L-lactide mini-tack placed through the ligament and a channel in the base of the proximal phalanx. The device stabilized the joint immediately, and 69 ligaments remained stable at 6 months. The subjective result was good or satisfactory in 66 of the cases. One case needed further surgery for pain in the scar and another developed local infection 9 months post-operatively. On the basis of these findings, the new absorbable fixation method seems to be a suitable method for clinical use.

Finnish Trauma Audit 2004: current state of trauma management in Finnish hospitals.

There is great variation in the organisation of trauma care in European countries. The state of trauma care in Finnish hospitals has not been appropriately reviewed in the past. The aim of the present study conducted by the Finnish Trauma Association (FTA) was to assess the number of Finnish hospitals admitting severe trauma patients, and to evaluate the organisation and training of trauma care in those hospitals. In 2004, a telephone survey to all the Finnish hospitals was conducted, and information on the number of severe trauma patients treated per month, the organisation of acute trauma care, and the existence of multidisciplinary trauma care training was collected. Thirty-six Finnish hospitals admitted trauma patients. The range of estimated number of severely injured trauma patients treated in individual hospitals per month varied from 0.5 to 12, resulting in an estimated number of 1000-1300 patients with severe trauma treated in Finland every year (19-25/100.000 inhabitants). About 20% of the hospitals had a trauma team, and 25% had a systematic trauma education program. Only one hospital had established multidisciplinary and systematic trauma team training. The case load of severe trauma patients is low in most Finnish hospitals making it difficult to obtain and maintain sufficient experience. Too many hospitals admit too few patients, and only a few hospitals have been working on updating their trauma management protocols and education. There is an obvious need for leadership, discussion, legislation and initiatives by the professional organisations and the government to establish a modern trauma system in Finland.

Coralline hydroxyapatite reinforced with polylactide fibres in lumbar interbody implantation.

Porous hydroxyapatite HA blocks reinforced with poly-l/dl-lactide fibres were used to maintain the lumbar disc space and to start to create intercorporeal fusion in 23 growing pigs. In four pigs two emptied non adjacent disc spaces were left open. After 3, 6, 12 and 16 weeks the implanted disc blocks were studied radiologically, histologically, histomorphometrically, microradiographically, and with oxytetracycline fluorescence. In plain films slight to moderate ossification of the implanted disc spaces was detected at 12 and 16 weeks. Resorption of the implants was seen radiologically from 3 weeks and fragmentation from 12 weeks onwards. In microradiographs disintegration of the coralline inner structure started at 3 weeks. Histologically, connective tissue ingrowth was seen inside the porous structure from three weeks onwards. Small amounts of new bone were visible and connective tissue inside the implant increased from a mean of 65.6% at 3 weeks to a mean of 79.4% at 16 weeks histomorphometrically. The bone ingrowth varied from 0.7 to 1.7%. A loss of height in the implanted disc spaces was seen (p < 0.05, linear regression analysis). In control pigs the emptied disc spaces lost their height similarly. The implants used were not strong enough to maintain the lumbar disc height.

Fixation of rabbit osteotomies with biodegradable polyglycolic acid thread.

In 68 rabbits, osteotomies of the femoral medial condyle were fixed with either liquid n-buty-2-cyanoacrylate, bone cement and biodegradable polyglycolic acid (PGA) thread, or PGA thread only. Follow-up times were 1, 3, 6, 12, 24, and 48 weeks. Macroscopic, radiographic, histologic, microradiographic, and oxytetracycline labeling studies were performed. Microscopically, the medial condyles fixed with the combined materials healed in 8 of 34 rabbits and with PGA threads in 22 of 34.

Left atrial rupture following blunt thoracic injury. Case report.

A 22-year-old man presented with intermittent tachycardia and left-sided flail chest after an automobile accident. Initially his condition was stable, but 7 hours after the injury cardiac asystole appeared. Cardiopulmonary resuscitation was immediately begun and operation was performed. A rupture of the left atrium was successfully repaired without cardiopulmonary bypass.

Medetomidine--ketamine--diazepam anesthesia in the rabbit.

Orthopaedic operations were performed in 340 rabbits when developing biodegradable rods for the fixation of fractures. The rabbits were anaesthesized by injecting medetomidine combined with ketamine and diazepam (MKD) subcutaneously. The mortality due to the anaesthesia was zero. Arterial blood gas analyses showed a moderate decrease in the haemoglobin oxygen saturation and compensated respiratory acidosis, which was well tolerated by the animals. It is concluded that MKD anaesthesia is well suited for orthopaedic operations in the rabbit.

A histomorphological study on self-reinforced polyglycolide (SR-PGA) osteosynthesis implants coated with slowly absorbable polymers.

A total of 150 osteotomies of rabbits' distal femur were fixed with absorbable self-reinforced polyglycolide (SR-PGA) rods coated with slowly absorbable polymers. In order to reduce the degradation rate of the SR-PGA construction rods were coated with n-butyl-2-cyanoacrylate, polydioxanone (PDS), poly-beta-hydroxybutyrate (PHBA), or poly-l-lactide (PLLA). Biocompatibility and the rate of biodegradation were evaluated in histological, histomorphometric, microradiographic, and oxytetracycline labeling studies. PDS, PHBA, and PLLA coatings showed good biocompatibility although there were scattered fluid accumulations around the rod in each group. Cyanoacrylate coating seemed to inhibit cartilage regeneration and cause the formation of considerable amount of connective tissue around the implant. The PGA core of the rod had totally degraded in 24 to 36 weeks in each coating group. Cyanoacrylate and PDS coatings were not detectable after 6 weeks while PHBA and PLLA coatings were still observed after 48 weeks. There were five (14%) non-unions in the cyanoacrylate coating group, one (3%) in the PHBA coating group caused by a purulent infection and none in the PDS and PLLA coating groups.

Degradable polyglycolide rods for the internal fixation of displaced bimalleolar fractures.

Cylindrical biodegradable rods of self-reinforced polyglycolide 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, 62 patients with displaced bimalleolar fractures were managed by open reduction and internal fixation using these rods. The results were assessed between 1.1 and 3.4 years from implantation. One wound infection occurred (1.6%). Five patients (8.1%) developed a sterile accumulation of fluid at the site of operation which required drainage: the final outcome was not affected. Minor displacement of the fracture (1-2 mm) occurred in nine patients (14.5%) but did not need further operation. The functional result was excellent in 39 patients (63%). This was considered acceptable given the severity of the fractures. Consequently, at our hospital, when a displaced malleolar fracture needs internal fixation biodegradable rods are now the treatment of choice. The psychological and financial advantages of avoiding implant removal are considerable.

Intramedullary fixation of cortical bone osteotomies with self-reinforced polylactic rods in rabbits.

Osteotomies of the femoral shaft in rabbits were fixed with intramedullary rods made of poly-L-lactic acid (SR-PLLA) and poly-DL/L-lactic acid (SR-PDLLA/PLLA). Follow up was from one week to 2 years. In the PLLA group, in 37 out of 40 osteotomies the fixation was firm and the bone was united. In the PDLLA/PLLA group, the fixation was firm in 30 out of 45, but in 13 of these angular deformity of more than 10 degrees had occurred. The fixation had failed in 15. No inflammatory or foreign body reaction was seen in either group. This study demonstrates that SR-PLLA rods are suitable fixation for cortical osteotomies in rabbits.

Reinsertion of the ruptured ulnar collateral ligament of the metacarpophalangeal joint of the thumb with an absorbable self-reinforced polylactide mini tack.

Total rupture of the ulnar collateral ligament of the first metacarpophalangeal joint is a common injury and it needs to be operated on, otherwise the injured joint will be unstable and it will cause disability due to loss of pinch grip. A special absorbable device--self-reinforced poly-L-lactide mini tack--was used to stabilise this ruptured ligament. 140 patients were operated on because of this ligament injury. The preliminary results after six months' follow-up were good. Normal movement was regained in 118 out of 140 patients (84.3%) and stability in 138 patients (98.6%). Five reoperations (3.6%) were needed--one because of scar pain, one because of local infection nine months postoperatively, one because of instability and two because of late loosening of the tack six and nine months postoperatively. Overall the preliminary results were good. On the basis of these findings we consider this new absorbable fixation method suitable for clinical use for reinserting the ruptured ulnar collateral ligament of the first metacarpophalangeal joint of thumb.

Fixation of experimental osteotomies of the distal femur of rabbits with biodegradable material.

Osteotomies of the distal femur in 19 rabbits were operatively fixed with totally biodegradable implants. Radiographic, histological, microradiographic, and oxytetracycline-labeling studies showing healing of the osteotomy within 6 weeks. The fixation proved stable sufficiently during healing of the osteotomized bone. The osteotomies united without delay and malalignment did not occur, although no external support was used and the rabbits were allowed to walk freely after the operation. Successful use of the biodegradable fixation developed in the present study was reported recently for the treatment of fractures of the ankle.

Fixation of experimental osteotomy of the distal femur with biodegradable thread in rabbits.

A distal femoral osteotomy on 24 rabbits was fixed with biodegradable polyglycolic acid (PGA) thread pulled through drill holes made on both sides of the osteotomy. Follow-up times were one, three, six, 12 and 24 weeks. The distal part of each femur was removed, fixed in alcohol, embedded in methylmethacrylate, sawed to 80 microns thick for oxytetracycline (OTC)-labeling studies and microradiography, and sectioned at 5 microns for histologic studies. As judged by histologic microradiographic, and OTC-labeling studies, 19 of 24 osteotomies were healing normally; after six weeks of follow-up examination, union of 11 of 14 osteotomies was observed on radiographs. On the basis of the present study, PGA threads may be promising for the fixation of osteotomies of the metaphyseal cancellous bone in rabbits.