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Two self-reinforced poly(L/DL)lactide 70:30 or self-reinforced poly (L/DL)lactide 70:30/ bioactive glass (SR-P(L/DL)LA/bioactive glass) composite rods (2 mm x 40 mm) were implanted into the dorsal subcutaneous tissue and osteotomies of the distal femur were fixed with these rods (2 mm x 26 mm) in 36 rabbits. The follow-up times varied from 3 to 100 weeks. After the animals were killed, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic and oxytetracycline-fluorescence studies of the osteotomized and intact control femora were performed. After 12 weeks the SR-P(L/DL)LA rods had fragmented into pieces and the mechanical properties could not be measured. The SR-P(L/DL)LA/bioactive glass rods lost their mechanical properties slower, and at 24 weeks the bending strength had decreased by 39% and the shear strength by 50%. After that the mechanical properties of the SR-P(L/DL)LA/bioactive glass rods could not be measured. All osteotomies healed well, and no gross signs of inflammatory reactions were observed. One slight displacement was seen in the three-week follow-up group with SR-P(L/DL)LA rods. Signs of resorption of the implants were seen after 48 weeks in the SR-P(L/DL)LA group and after 24 weeks in the SR-P(L/DL)LA/bioactive glass group. The SR-P(L/DL)LA/bioactive glass rods were almost totally resorbed from the bone at 100 weeks. The present investigation showed that the mechanical strength and fixation properties of the SR-P(L/DL)LA and the SR-P(L/DL)LA/bioactive glass composite rods are suitable for fixation of cancellous bone osteotomies in rabbits.

Twenty-four wrist arthrodeses were performed on 18 patients with rheumatoid arthritis using a bioabsorbable self-reinforced poly-l-lactide rod as the fixation device. There was one nonunion which required a re-operation and two nonunions which did not need further treatment. The position of the arthrodesis was ulnar deviation and extension in most patients, and there was high patient satisfaction with 21 of the 24 wrists and satisfactory pain relief in 22 of the 24 wrists. This method for fusing the wrist in patients with rheumatoid arthritis appears reliable and simple to perform.

Self-reinforced poly(desamino tyrosyl-tyrosine ethyl ester carbonate) poly(DTE carbonate) rods (diameter, 2 mm; length, 26 mm) were implanted into the dorsal subcutaneous tissue of 16 rats. Osteotomies of the distal femur were fixed with these rods (2 mm by 15 mm) in 64 other rats. The follow-up times varied from 1 week to 1 year. After sacrifice, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of the osteotomized and intact control femurs were performed. At 36 weeks, the bending strength of the rods was nearly at the same level as the initial value, and the shear strength was decreased to about one quarter of the initial value. One of the 64 evaluated osteotomies showed signs of infection at 24 weeks, and there were five failures of fixation. Fifty-eight osteotomies healed uneventfully. No gross signs of inflammatory or foreign-body reactions were observed. The present investigation showed that the mechanical strength and fixation properties of SR-poly(DTE carbonate) rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on successful application of SR-poly(DTE carbonate) rods for fixation of cancellous bone osteotomies.

This is an analysis from one hospital of the first 1043 operations where pure self-reinforced poly-L-lactide (SR-PLLA) implants have been used alone. The operations were performed between 1988 and 1999 and included 407 orthopaedic patients and 636 trauma patients. There was a total of 107 complications. There were 21 infections but no sinus formation. Failure of fixation was seen in 46 patients. In 936 operations the healing was uneventful.

Drawn self-reinforced polyglycolide (SR-PGA) rods, O 2 mm and 26 mm long, were implanted in the dorsal subcutaneus tissue of 16 rats. Osteotomies of the distal femur were fixed with SR-PGA rods (2 mm by 15 mm) in another 38 rats. The follow-up times varied from one week to one year. After sacrifice, three-point bending and shear tests were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of osteotomized and intact control femora were also performed. At three weeks the flexural strength of the rods was 50% of the initial value, and the flexural modulus was 46% of the initial value. Five osteotomy specimens had to be excluded due to dislocation or non-union. One of the 33 evaluated osteotomy specimens showed signs of postoperative infection. Thirty-two osteotomies healed uneventfully. No gross signs of inflammatory or foreign-body reaction were observed. The amount of osteoid surface and active osteoid formation surface reached their highest value in the histomorphometrical analysis at 24 weeks. The present investigation demonstrated that the mechanical strength and fixation properties of the drawn SR-PGA rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on the successful application of drawn SR-PGA rods for fixation of cancellous bone osteotomies.

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.

Objective: Implants made of self-reinforcing polylevolactic acid (SR-PLLA) have been successfully used in arthrodeses of patients with rheumatoid arthritis. No long-term evaluation on bioabsorbable fixation in patients with rheumatoid arthritis has been published so far. Methods: In this study 21 wrist fusions were performed on 18 patients with rheumatoid arthritis by using SR-PLLA rods as fixation devices. The follow-up time was 3-8 years (mean 5.4 years). Results: The results showed one non-union but no infections or problems associated with the bioabsorbable implants used. Conclusion: According to this study, fixation of wrist arthrodesis in patients with rheumatoid arthritis can be performed by using SR-PLLA implants with favourable results. The benefit of this method is the avoidance of the removal operation of fixation devices.

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.

Metacarpophalangeal (MCP) joints are the most commonly and usually first affected joints in rheumatoid arthritis (RA). The natural history of the affected MCP joints includes local swelling that leads to distension of joint capsule and ligamentous structures. Later on as destruction of cartilage surfaces proceeds a volar subluxation and ulnar drifting of proximal phalanges appear. This causes an imbalance of the intrinsic tendons, which leads to swan neck or boutonniere deformities of the fingers.1,2 In addition to oral antiinflammatory analgetics, intraarticular corticosteroid injections are the most common conservative method of treatment. The results of chemical synovectomy in digital joints using thiotepa has been reported to give favourable results, but further studies are still needed.3 The goals of hand surgery in rheumatoid patients are relief of pain, improvement in function, retardation of progress of the disease and improvement in appearance. Surgical synovectomy is usually the first operative procedure to treat the hand and wrist joints in cases of moderate but chronic synovitis. Synovectomy should not be used for patients with rapidly advancing joint disease. Later on, as destruction of the joint proceeds, fusion of the wrist and interphalangeal (IP) joints is still more often advocated than arthroplasty operations. However, fusion of the MCP joint (other than the second MCP joint) is not recommended

Self-reinforced polylevo-dextro-lactic acid (SR-PLA) 70 composite rods, (2 mm x 26 mm) were implanted in the dorsal subcutaneus tissue of sixteen rats. Osteotomies of the distal femur were fixed with SR-PLA70 composite rods (2 mm x 15 mm) in 39 rats. The follow-up times varied from 1 week to 1 year. After sacrifice three-point bending and shear tests were performed for subcutaneously placed rods, and radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of osteotomized and intact control femora were performed. At 52 weeks the shear strength and flexural modulus of the rods were 41% of the initial value, and the flexural strength was 43% of the initial value. In the osteotomies seven specimens had to be excluded due to postoperative infection or dislocation of the fragment. Six of the thirty-two evaluated osteotomies showed signs of postoperative infection. Twenty-six osteotomies healed uneventfully. No signs of inflammatory or foreign-body reaction were observed. The present investigation demonstrated that the mechanical strength and fixation properties of the SR-PLA70 rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on successful application of SR-PLA70 rods for fixation of cancellous bone osteotomies studied.

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

Objectives. Inflammatory arthritides/synovitides such as psoriatic (PsA), reactive (ReA) and rheumatoid (RA) arthritis share numerous immunopathological features, but develop diVerent patterns of joint involvement. To investigate whether distinctive cell apoptosis may play a role in this context, we have assessed synovial cell apoptosis in situ in PsA and ReA, and compared it with RA and ‘non-inflammatory’ controls. Methods. TdT-mediated dUTP nick end-labelling ( TUNEL) of DNA breaks complemented immunoperoxidase staining for CD68 or LCA as the specific cell markers. Results. The proportion of apoptotic synovial lining cells was high in PsA, ReA and RA compared to values in controls (P< 0.05). No diVerences existed between these inflammatory arthritides in numbers or type of apoptotic lining cells. In RA, however, in contrast to PsA and ReA, apoptotic lining cells were clustered or, in a small subset of samples, were very low in number. Prominent apoptosis of inflammatory cells in the sublining in ReA has accounted for higher overall apoptotic cell numbers in synovial stroma (sublining+ perivascular inflammatory cell infiltrates) in this condition than in RA or PsA (P< 0.05). Conclusions. No disease-specific pattern in the phenotype of apoptotic synovial lining cells could be suggested in any of the inflammatory arthritides studied. However, topological diVerences in the lining and quantitative diVerences in the inflammatory cell apoptosis in synovial stroma may in part explain the occurrence of the prominent synovial lining cell hyperplasia distinguishing RA from ReA and PsA. On the other hand, relatively frequent inflammatory cell apoptosis may contribute both to the downregulation of synovial inflammation and to the control of synovial lining hyperplasia in ReA.

Between November 1984 and January 1994 in our department, a total of 2500 patients were treated with totally absorbable internal fixation devices. We studied these patients and analyzed results with regard to the volume of the absorbable implants and the development of wound infection. Of the 2500 patients 2044 were trauma patients and 456 were operated on for orthopedic disease. In 1466 patients treated with implants made of self-reinforced polyglycolic acid (SR-PGA) only, the patients who developed wound infection had a higher implant volume (P = 0.07) than those who did not; this difference was close to statistical significance. In the 446 patients who received only implants made of self-reinforced poly-L-lactic acid (SR-PLLA), the 5 who developed wound infection had a mean implant volume more than three times that of the non-infected patients (P = 0.01). We found that in the patients treated with the earlier SR-PGA implants, which contained a green staining material, there was no correlation between implant volume and incidence of wound infections. On the other hand, both the non-stained SR-PGA implants, which have been in clinical use since 1989, and the SR-PLLA implants, seem to be more predictable in terms of wound infections. We believe that this difference is largely due to the lower level of tissue reactions with these newer implants.

The effect of the manufacturing method on the strength retention of self-reinforced poly-L-lactide (SR-PLLA) screws was studied in vitro and in vivo from 3 up to at least 15 weeks. SR-PLLA screws were manufactured from axially oriented SR-PLLA billets by the conventional compression moulding process and an in-house developed machine cutting technique. New machined SR-PLLA screws (thread diameters 4.5 mm and 3.5 mm) were significantly stronger than older compression moulded SR-PLLA screws (4.5 mm and 3.5 mm) in bending and torque strength tests but significantly weaker in shear strength tests. In pull out tests there were not significant strength differences between the screws. Mechanical analysis and molecular weight measurements confirmed earlier observations that SR-PLLA degrades faster in vivo than in vitro. These results suggest that the new screws could be suitable for clinical use.

The outcome of olecranon and patella fractures fixed with biodegradable implants (self-reinforced poly-L-lactide wire combined with self-reinforced polyglycolide screw or self-reinforced poly-L-lactide plug) or with metallic implants (tension band wiring, Kirschner wire and metallic cerclage wire) was compared in a prospective, randomized study. Twenty-five olecranon fractures (15 with biodegradable implants and 10 with metallic ones) and 10 patella fractures (6 with biodegradable implants and 4 with metallic ones) were treated. There were no differences between these methods in outcome. Olecranon and patella fractures can be treated using biodegradable implants successfully. The total expenses are lower because a second operation is not needed to remove the implants after fracture consolidation.

In this experimental study with bone defects, we focussed on the one hand on external and internal osteogenic callus formation after filling the defect and on the other on the osteochondrogenic differentiation capacity of 4-day-old fibrous-like callus grafts and 12-day-old woven bone grafts in an osteogenic environment. A standard cortical bone defect of the femur was created in 95 young rats. The defect was filled with a cortical bone graft and 4- and 12-day-old callus grafts. The grafts were transplanted as such or in Nucleopore chambers. Follow-up was done at 1, 2, 3 and 6 weeks. The osteochondrogenic tissue formed was studied histologically and histomorphometrically. The results suggest that the filling of the bone defect had no influence on the primary external and internal osteogenic callus formation at 1 and 2 weeks. At 3 and 6 weeks in the chamber groups the persisting internal bridging woven bone was converted into more compact lamellar bone whereas periosteal callus remained at the edges of the defect. In the other groups at 3 and 6 weeks the normal shape of the cortex was reconstituting. Four-day-old fibrous-like callus formed bone in the Nucleopore chamber, indicating that fibrous-like callus tissue at 4 days contains osteogenic cells. Twelve-day-old callus consisting of woven bone was partially differentiated to cartilage, showing that woven bone contains cells capable of chondrogenic differentiation.

In this series absorbable fixation devices (screws and rods) made of self-reinforced poly-L-lactide (SR-PLLA) were used to stabilize arthrodesis in rheumatoid arthritis. These fixation devices have been used mainly in the fracture treatment or in the fixation of osteochondral lesions or osteotomies in hallux valgus operations. In arthrodesis of post-traumatic arthritis these devices have been used successfully. Fifty-three arthrodeses (18 in the wrist, 18 in the hand, 6 talocrural joint and 11 subtalar-calcaneocuboid-talonavicular joint) were performed for 47 patients using absorbable screws and rods between 1989 and 1994. Overall results in every group were good. There were 3 superficial infections and 2 nonunions (both talocrural arthrodesis). According to this study it seems that absorbable screws and rods are interesting alternative fixation devices in arthrodesis in rheumatoid arthritis.

The purpose of this experimental investigation was to study the incorporation of porous glassy carbon in bone. Cylinders of porous glassy carbon were implanted in drill holes in diaphyses and metaphyses of rabbits tibia for 1, 3, 6, 12 and 24 weeks. Bone ingrowth into the glassy carbon implants was examined by radiographic, histologic, fluorocrome and microradiographic methods. The material caused no pathological reaction. Tissue ingrowth into pores was seen by all examination methods. The amount of bone in the pores increases with time. The ingrowth was most distinctive in those areas where the implant was in close contact with cortical bone or trabeculae of the cancellous bone. Porous glassy carbon can be used as bone substitute, although the small size of implant available is at the present a limitation for its clinical use.

The right distal femur of 42 adult rabbits was osteotomized and fixed with two 1.5 mm in diameter metallic Kirschner wires, self-reinforced polyglycolic acid (SR-PGA, Biofix®), or self-reinforced poly-L-lactic acid (SR-PLLA) rods. Follow-up times were 6 and 12 weeks. The shear strength of 30 pairs of femora was investigated. The strength of osteotomized bones was compared with the non-osteotomized controls. After six weeks the operated femora had reached 70, 69 and 71% shear strength in metallic, SR-PGA and SR-PLLA groups, respectively. After 12 weeks the shear strength values were 75, 79 and 73%, respectively. There was no statistically significant difference in shear strength values between the groups. Twelve pairs of femora were studied with microradiographic, oxytetracyclic fluorescence, and histologic methods. Normal bone healing was seen in these samples. Metallic and SR-PLLA implants caused slight foreign-body reaction with giant cells and SR-PGA rods led to slight infiltration of macrophages and foam cells.

A patient who had had been treated by surgery for spinal echinococcosis in a Mediterranean country emigrated to northern Europe. After surgery, the echinococcosis disseminated and he developed chronic lytic and sinus-draining hydatid disease of the left hip and neuromuscular weakness of the left lower extremity. Seventeen years after the spinal surgery, he was referred to our hip service for a possible total hip replacement (THR) after receiving adequate chemotherapy against echinococcosis for nearly 3 years. Because of the poor results reported by others, we decided against THR; two of the four previous patients described in the current literature who had THR died due to complications.

The effects of low-intensity pulsed ultrasound (30 mW/cm2) were investigated in experimental cancellous bone fracture healing in bioabsorbable self-reinforced poly-L-lactide (SR-PLLA) rod fixed distal femur osteotomy in rats. A transverse transcondylar osteotomy was fixed with one SR-PLLA rod in 32 male Wistar rats of the age of 20 weeks. Half of the rats had a daily 20-min ultrasound exposure for three weeks. The follow-up times were three, six, and 12 weeks. Radiographical, histological, microradiographical, oxytetracycline labeling, and histomorphometrical analyses were performed. No foreign-body reactions were noted. The biocompatibility of SR-PLLA and ultrasound was found to be good. In the radiological and histological assessments there was a slight tendency for enhanced healing in the ultrasound group at three weeks, but at six and 12 weeks no differences were observed. The histomorphometrical and oxytetracycline labeling analyses showed that ultrasound exposure had no significant effects on bone healing. The present study shows that there were no obvious findings to support the hypothesis that low-intensity pulsed ultrasound enhances bone healing in self-reinforced poly-L-lactide (SR-PLLA) rod fixed experimental metaphyseal distal femur osteotomy in rats. The observed good biocompatibility provides a safe starting-point for clinical trials on bioabsorbable fixation combined with low-intensity ultrasound.

Drawn self-reinforced polyglycolide (SR-PGA) rods, Ø 2 mm and 26 mm long, were implanted in the dorsal subcutaneus tissue of 16 rats. Osteotomies of the distal femur were fixed with SR-PGA rods (2 mm by 15 mm) in another 38 rats. The follow-up times varied from one week to one year. After sacrifice, three-point bending and shear tests were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of osteotomized and intact control femora were also performed. At three weeks the flexural strength of the rods was 50% of the initial value, and the flexural modulus was 46% of the initial value. Five osteotomy specimens had to be excluded due to dislocation or non-union. One of the 33 evaluated osteotomy specimens showed signs of postoperative infection. Thirty-two osteotomies healed uneventfully. No gross signs of inflammatory or foreign-body reaction were observed. The amount of osteoid surface and active osteoid formation surface reached their highest value in the histomorphometrical analysis at 24 weeks. The present investigation demonstrated that the mechanical strength and fixation properties of the drawn SR-PGA rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on the successful application of drawn SR-PGA rods for fixation of cancellous bone osteotomies.

Totally absorbable internal fixation devices have been used in a total of 2114 operations for the treatment of fractures, arthrodeses and osteotomies at our department between November 1984 and December 1992. The infection rate was 3,5%, for pure polyglycolide (PGA) implants 4% and for pure polylactide (PLLA) implants 0,7%. When the fixation with absorbable implants was compared to that of metallic implants in another series the infection rates were 4% and 9%, respectively. This difference was due to technical reasons. Sinus formation due to a foreign body reaction was observed in 2,5% of 2114 cases and was subsequently infected in 20%.

Two self-reinforced poly(desamino tyrosyl-tyrosine ethyl ester carbonate), poly(DTE carbonate) or self-reinforced poly(DTE carbonate)/bioactive glass rods, (2 mm by 40 mm) were implanted into the dorsal subcutaneous tissue and osteotomies of the distal femur were fixed with these rods (2 mm by 26 mm) in 36 rabbits. The follow-up times varied from three to 100 weeks. After sacrifice, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of the osteotomized and intact control femora were performed. The initial mechanical properties were higher with the SR-poly(DTE carbonate) rods, but the SR-poly(DTE carbonate)/bioactive glass rods lost their mechanical properties slower. At 100 weeks the bending strength had decreased to 21% of the initial value with the SR-poly(DTE carbonate) rods and to 49% with the SR-poly(DTE carbonate)/bioactive glass rods. The shear strength had decreased to 10% with the SR-poly(DTE carbonate) rods and to 23% of the initial value with the SR-poly(DTE carbonate)/bioactive glass rods. Two slight displacements and one delayed union and one failure of fixation were seen in the SR-poly(DTE carbonate) group. In the SR-poly(DTE carbonate)/bioactive glass group five delayed unions and seven slight displacements were seen. No signs of osteolysis or foreign body reactions were observed. Signs of resorption of the implants were seen at 100 weeks in the SR-poly(DTE carbonate)/bioactive glass group. The present investigation showed that the mechanical strength and fixation properties of SR-poly(DTE carbonate) and SR-poly(DTE carbonate)/bioactive glass rods are suitable for fixation of cancellous bone osteotomies in rabbits.

The causes of a clinical tissue response to self-reinforced polyglycolide (SR-PGA) and self-reinforced polylactide (SR-PLLA) implants were studied in the first 2500 polymeric fixations. The incidence was 8.0% in fixations with implants made of SR-PGA (n = 1879) and 0% in SR-PLLA fixations (n = 621). A small number of fixations per site seemed to increase the incidence of a tissue response. In diagnoses involving over 50 fixations, except for ankle fractures, the incidence was 4.2%. The site of fixation influenced the incidence; the lowest incidence was seen for radial head fracture fixation (1.1%). The aromatic dye which has not been used since 1988 in the SR-PGA implant increased the response. A large total implant volume and a large number of implants increased the incidence of a tissue response. In the knee (n = 131), the incidence of a clinical tissue response was 4.3%, with four fluid accumulations and one synovitis of the knee after fixation with SR-PGA implants.

The effect of a bioabsorbable pin containing transforming growth factor-beta(1) on fracture healing was studied in a rat model. The growth factor was mixed into a bioabsorbable polymer paste (a blend of an l-lactic acid oligomer and a copolymer of epsilon-caprolactone and dl-lactide) that was used to fill the grooves of a self-reinforced fracture fixation pin made of a poly-ld-lactic acid copolymer. In an in vitro assay, sustained release of the growth factor from the pins over a 7-day period was demonstrated. A distal femoral osteotomy was made in 60 rats and stabilized with the fracture fixation pin in 48 of them; In the remaining 12 rats, no fixation was performed. The pin used in the study group contained either 5 microg (15 rats) or 50 microg (15 rats) of the growth factor, while in a control group of 18 rats an identical pin without the growth factor was used. After a follow-up of 1, 3, or 6 weeks, the femurs were examined radiographically, histologically, histomorphometrically, and microradiographically, and also used in tetracycline labeling studies. Faster callus formation was evident in the growth factor-treated rats but no acceleration in the healing of the osteotomy was detected.

Osteotomies of the distal femur were fixed with two self-reinforced poly-L-lactic acid (SR-PLLA) plates and metallic screws placed through the plates on each side of the femur in 23 adult rabbits. They were followed-up after 3, 6, 12 and 24 weeks. After killing, radiological, histological, microradiographic and oxytetracycline fluorescence studies were performed. Except for one histologically confirmed fibrotic non-union at 24 weeks, the osteotomies healed, including one involving a rabbit which had suffered an ipsilateral femoral shaft fracture of unknown cause. No malformations were observed, and the macroscopically detected swelling was a normal postoperative reaction. This study showed that SR-PLLA plates implanted on both sides on the bone are suitable for the fixation of weight-bearing cancellous bone osteotomies in rabbits.

The economic costs of ankle fractures treated operatively with self-reinforced polyglycolide acid (SR-PGA) screws, with self-reinforced poly-L-lactide acid (SR-PLLA) screws or with metallic implants was determined. All patients were divided into three groups according to the fixation material used. Open and otherwise complicated fractures were excluded. The total expense of operations in each group was taken into account. The average total cost of an ankle fracture fixed with SR-PGA screws was Pounds 3503. In the SR-PLLA group it was Pounds 3906, and in the metallic group it was Pounds 4514. Total expenses were Pounds 1011 higher in the metallic group than in the SR-PGA group, and consequently, expenses in the metallic group were Pounds 608 higher than in the SR-PLLA group. According to this study, it seems that absorbable fixation devices are more economical than metallic implants in operative treatment of ankle fractures though as part of the differences in total expense in this series is due to the age of the patients and other dissimilarities between these groups, the results have to be interpreted carefully.

Osteotomies of distal femur were fixed by intraosseous self-reinforced poly-L-lactic acid (SR-PLLA) plates in 29 adult rabbits. The follow-up times were from 3 to 24 weeks. After sacrifice, radiological, histological, microradiographic, and oxytetracycline fluorescence studies were performed. Although radiographically no redisplacements were found, in 12 weeks two fixations were broken and a fibrotic nonunion was observed in one case. At 24 weeks full bone consolidation was seen in all except one osteotomy. No foreign-body reactions were observed. The present article is the first report on successful application of absorbable plates for intraosseous fixation of weight-bearing bone osteotomies. The present investigation demonstrated that the SR-PLLA plates were suitable for the fixation of cancellous bone osteotomies in rabbits.

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.

Cartilage regeneration was studied in an experiment in rats. A standardised full-thickness articular cartilage defect was created and autogenous 12-day-old callus or cortical bone graft was transplanted into it, or the defect was left empty. The follow up periods were three, six, 12, and 24 weeks, and each subgroup consisted of five animals. A total of 60 animals were operated on. From six weeks onwards hyaline-like cartilaginous tissue had started to develop at the edges of the defect in all three groups. In the middle section of the hole, however, the picture was different; at 24 weeks none of the specimens in the defect group, two of the five in the callus graft group, and all five in the bone graft group had developed full-thickness, hyaline-like cartilaginous regeneration. The hyaline-like cartilaginous tissue in the medical segment was hypocellular when analysed by histomorphometry. On scanning electron microscopy the surface of the reparative tissue looked fibrillated in all specimens from the three groups.

We studied absorbable self-reinforced poly-L-lactide screws in the fixation of osteotomies in sheep. A left olecranon osteotomy in 10 sheep was fixed with polylactide screws and in an additional 10 sheep with metallic AO cortical screws. Follow-up times were 6 and 12 weeks. 8 polylactide fixations healed and 2 failed. All metal fixations united; one of them had a fracture of the proximal fragment resulting in malposition. After killing the sheep the olecranons were radiographed and the shear strengths of the osteotomies were compared with those of the non-operated contralateral bones. After 6 weeks the mean comparative strength was 74 percent in the polylactide group and 83 percent in the metallic control group. After 12 weeks the corresponding values were 112 and 47 percent (P less than 0.05). Our study demonstrated that the mechanical weakening of fixed bone can be avoided by using absorbable polylactide screws instead of metallic screws. However, polylactide screws are not recommended for use without external support in places of high mechanical strain.

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.

Sixteen patients with dislocated ankle fractures fixed between 1988 and 1991 with self-reinforced poly(L-lactide; SR-PLLA) screws and/or rods were followed up after 8.6 to 11.7 years (mean 9.6 years) at the Department of Orthopaedics and Traumatology, Helsinki University Central Hospital. In all patients accurate reduction of the fractures was retained and uneventful bony union was achieved. Good or excellent long-term functional results were observed in 15 out of 16 patients. One patient had post-traumatic osteoarthritis. In 5 patients, a late tissue reaction was observed over an extruding screw head with mild symptoms, which led to removal of small palpable masses. There were two superficial wound infections, one after a primary operation and one caused by a late tissue reaction after an operation. The correct operative technique, where all extruding extraosseous SR-PLLA material should be removed during the primary operation, should be followed.

Of 98 patients with fracture of the thoracic spine (Th1–Th11) treated at the Central Hospital of Tampere in 1968–1975, 75 (77%) were seen after an average of 5 years and 4 months. Nearly half (49%) the injuries were sustained in road accidents and 36% were due to falling. Anterior wedge fracture was present in 91 %. Two patients died in the hospital of their thoracic spine fracture. Neurological symptoms developed in 9 cases; seven of these patients showed paraplegia. The treatment was mainly conservative and consisted of early functional exercise. Reduction and osteosynthesis were carried out on 2 patients with incomplete cord lesions. The patients were mobilized after 17 days on the average, and the mean hospital stay was 19 days. Working capacity was preserved in 85% of the patients and half returned to work within three months. During the observation period compression deformity was corrected in 6% of the patients, while all other deformities were aggravated. The neurological state deteriorated during the observation period in 3 patients and was improved in none. Over half the patients considered the state of their back as at least good. The clinical results were significantly worse in patients over 40 than in the younger patients. Paraplegia was significantly more frequent in patients showing marked deformities on admission. Poor clinical results correlated significantly with radiological deformities observed on admission.

In a series of 149 fractures of the thoracolumbar junction (Th12-L1), treated at the Central Hospital of Tampere from 1968 to 1975, 101 patients were seen after an average interval of 5 years. Over half of the fractures were sustained at home or in leisure hours. Over 90% were anterior wedge fractures. One patient died in the hospital of other injuries. The injury caused peraplegia in three cases and other neurological lesions in six. The treatment was conservative except in the patients with paraplegia, who were surgically treated. The patients were mobilized after an average of 15 days. The neurological condition did not deteriorate. Noteworthy changes of the radiological findings occurred during follow-up. The clinical result was considered good in two thirds of the patients, and 91% were able to return to work. The frequency of neurological findings was significant in patients showing radiological deformities. The force responsible for the fracture correlated with the radiological findings and the occurrence of neurological lesions. Narrowing of the vertebral canal and degenerative changes observed on admission had a significant and unfavorable effect on the clinical result.

This study was designed to evaluate the growth of bone into porous glassy carbon cylinders. Porous carbon cylinders were implanted in 30 rabbits intra-articularly in the metaphysis of the femur opposite from the patella. The rabbits were sacrificed up to 24 weeks after the operation. The bone samples were examined by histologic, fluorochrome and microradiographic methods. The amount of bone ingrowth was measured histomorphometrically. Fluorochrome uptake was seen in the implant pores, which indicated new bone growth originating from surrounding bone. After 3 weeks, microradiographs revealed new bone formation in the pores and with time the bone spicules became more dense. The amount of bone tissue in the pores grew and reached a maximum at 12 weeks, when 45 per cent of the total pore volume was incorporated with bone tissue. No adverse tissue responses were observed.

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.

Five hundred and ninety-eight cases were studied where the patients had been subjected to skull radiography because of a head injury. Concussion had been established in 231 patients and a more severe brain injury in 8. Forty-nine patients (8.2 per cent) had skull fractures. The relative frequency of fractures was the highest among those aged between 40 and 59 years (16 per cent). From among 16 variables, either clinical or pertaining to the history, 4 had clearly sustained a fracture of the skull, the statistically significant features being amnesia, unconsciousness for over 30 minutes, a wound and subcutaneous haematoma in the scalp and a reduced level of consciousness. On the basis of these signs the patients could be divided into two groups which differed in the frequency of skull fractures by a factor of five. The skull fracture was not observed to have influenced the patient's care or recovery, particularly if the patient had a concurrent brain injury. Based on the results, the indications for skull radiography in patients with head injuries can be identified and this can reduce the need for X-ray examinations to one-half and still reveal 80 per cent of skull fractures.

The aim of the study was to measure the shear strength of bone/porous-glassy-carbon interface in rabbit. Glassy carbon pellets were implanted into drill holes made through the medial articular surface of the proximal tibia of 15 rabbits. Shear strengths grew statistically significantly from 1 to 6 weeks and reached a maximum of 4.6 MN/m2. Microscopical examination of the sheared surfaces revealed that at 1 and 2 weeks the shearing occurred through the tissue surrounding the implant, and at 3, 6 and 12 weeks through the porous coating of the implant. To diminish the fragility of the porous coating, its porosity should be adjusted to 40%. Results of shear strength studies on current implant materials are reviewed.

Seventy-one patients of 119 with injury of the cervical spine were re-examined an average of 5 years and 5 months after the accident. The mean age of the patients was 39 years. There were 91 male and 28 female patients. The majority of injuries (51) were sustained by car drivers and passengers involved in traffic accidents. More than one cervical vertebra was damaged in 36 patients. Neurological lesions were observed in 59 patients; tetraplegia was present in 19 of these. The average duration of hospital treatment was 37 days. Twenty-four patients were treated at the intensive care unit. Skull traction was used in 69 cases for an average of 38 days to bring about reduction and immobilization. Reduction and anterior spondylodesis by Cloward's technique was performed on 13 patients. Of the operated patients, 11 showed root symptoms or incomplete cord lesions. The 19 tetraplegics were all conservatively treated. Fourteen patients died of their cervical spine injuries and 7 remained permanently disabled. Half the patients recovered to a pain-free state and one third became asymptomatic. Of the radiological deformities observed on admission, lowering of the disc space increased during follow-up, and forward sliding, increase in interspinous distance and narrowing of the vertebral canal decreased. The clinical result was poorer if flexion deformity, compression, forward sliding, narrowing of the vertebral canal or lowering of the disc space were observed at the last radiological examination.

In this study the cost-benefit ratio of posterior fusion of the lumbosacral spine was assessed. The calculations were based on 118 operated patients, followed up for an average of 4.8 years. Costs were calculated using the average costs of treatment at central hospitals, visits to the outpatient department and travelling. The costs for one patient exceeded on average 5,569 US dollars. The economic benefits derived from the operations were estimated by the work output of those 36 patients who postoperatively returned to their previous or a corresponding occupation. The postoperative work output was estimated using the coefficients for known causes of retirement (emigration, mortality, disability). The benefits of one lumbosacral fusion amounted on average to 16,075 US dollars. Fusion of the lumbosacral spine prove to be profitable at a cost-benefit ratio of 1 : 2.9. If the selection of patients for operation could be made so as to guarantee that working capacity is restored by operative treatment, the cost-benefit ratio might be improved to 1 : 9.5. It is emphasized that cost-benefit analyses of surgical procedures are important from the standpoint of principles of treatment and priority of operations. This study deals with economic aspects only. The medical aspects of the present material have been presented in two previous papers.

This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.

Fifty-nine patients with immediate and 16 with secondary radial nerve palsy complicating a fracture of the shaft of the humerus were reviewed. According to the preferences of the surgeon in charge, the palsy was treated either with early exploration of the radial nerve and internal fixation of the fracture or with initial expectance. Of the latter, 12 were later explored. No useful recovery of motor function could be seen in 13/59 patients with immediate and in 2/16 patients with secondary palsy. In patients with immediate palsy treated by early exploration, there were 8/27 nonrecoveries. Among those treated with initial expectance, there were 5/32 nonrecoveries. For secondary palsy, these figures were 2/10 and 0/6, respectively. No support emerged for routine early exploration.

The clinical, radiographic and operative findings in 64 consecutive acute dislocations of the patella were analyzed. Both patellofemoral joints were symptomless before dislocation in 58 patients. The sulcus angle of the femur on the affected side was larger than on the contralateral side in one half, and a fresh marginal patellar fracture was demonstrated in one third of the cases. The stability of the patella could not be reliably estimated in tangential views taken with the knee in 20 degrees flexion; especially false negative findings were numerous.

Fracture of the tibial tuberosity is an uncommon injury and rarely occurs after closure of the proximal tibial epiphysis. Three cases of tibial tuberosity fracture over a period of 11 years were treated by open reduction, internal fixation, and immobilization for 6 weeks in plaster of Paris (1970-1980). The postoperative follow-up times were 5, 6, and 7 years. No subsequent deformities were detected. Two patients had secondary posttraumatic patella infera without any symptoms. All patients returned to normal activity. The results demonstrated that this injury in the adolescent knee heals without deformity of functional loss when adequate reduction and fixation of the fracture fragments have been achieved.

Fourteen children with severely displaced diaphyseal fractures of both bones of the forearm treated with open reduction and internal fixation were reviewed; these operations represented 9 per cent of all the diaphyseal forearm fractures in children during a 9-year period. The mean age of the patients at the time of the injury was 12 (7-14) years; they were reexamined 8 (5-11) years later, all after cessation of growth. At follow-up, limited prosupination, observed in 8 patients, was associated with a fracture of the proximal third of the forearm; limited motion of the radiocarpal joint, in 2 patients, was associated with shortening of the ulna. Only 4 patients complained of pain or were aware of restricted motion, and the average function was good. Open reduction and internal fixation is indicated in displaced fractures of the forearm even in children.