Causes of the clinical tissue response to polyglycolide and polylactide implants with an emphasis on the knee.

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.

Comparison of polylactide screw and expansion bolt in bioabsorbable fixation with patellar tendon bone graft for anterior cruciate ligament rupture of the knee. A preliminary study.

In a preliminary study, 24 patients with rupture of the anterior cruciate ligament (ACL) were operated on using implants made of self-reinforced poly-l-lactide (SR-PLLA). The operation method was outside-in bone-tendon-bone reconstruction. In 10 patients the fixation was made with an SR-PLLA screw with a diameter of 6.3 mm, in 12 with an SR-PLLA expansion plug with a diameter of 6.0 mm, and in two cases both implants were used, but these cases were excluded from comparison. The purpose of the study was to evaluate and compare the use and fixation results of these two implants. The follow-up time averaged 3.2 years. Twenty patients attended follow-up. On subjective evaluations, seven of the eight patients following SR-PLLA screw fixation and six of the ten after expansion plug fixation regarded their knee as normal or nearly normal. Arthrometric testing showed the side-to-side difference to average 2. 9 mm following SR-PLLA screw fixation and 2.6 mm after expansion plug fixation (NS). Six of the patients had giving-way symptoms (two after screw fixation and four after plug fixation). The pivot shift test was slightly positive in two patients and positive in one patient after SR-PLLA screw fixation, and in three knees slightly positive and in another three knees positive following expansion plug fixation. Radiography showed variation in the location and orientation of the bone channels. Magnetic resonance imaging was performed in seven cases, and in two cases an edema was found in the tendon of the anterior cruciate ligament graft and in six cases the implants were visible. No statistical difference in results between the SR-PLLA screw and SR-PLLA expansion bolt was noted. Fixation with expansion plug seems technically more challenging, with a tendency to inferior results compared to screw fixation. In the absorbable fixation of a bone-tendon-bone graft there are no metallic artifacts on magnetic resonance imaging and no need to remove the fixation material regarding the revision surgery.

Bioabsorbable fixation in the treatment of proximal tibial osteotomies and fractures. A clinical study.

BACKGROUND AND AIMS: The purpose of this study was to evaluate the use of bioabsorbable implants in proximal tibia cancellous bone fixations in 28 patients. PATIENTS AND METHODS: The implants used were self-reinforced polyglycolide (SR-PGA) or self-reinforced polylactide (SR-PLLA) screws or rods. In six patients a high tibial osteotomy and in 16 patients a proximal tibial plateau fracture were secured with these implants (cancellous bone fixations). In addition, four anterior tibial eminence avulsion fractures and two tibial tuberosity avulsions were fixed (avulsion fractures). The average follow-up time was 3.6 years. RESULT AND CONCLUSIONS: In the cancellous bone fixations (15 patients at the follow-up) there were three excellent clinical results, five good, five moderate and two poor results; radiologically there were one excellent result, eight good, five moderate, and one poor result. In the avulsion fracture patients (four patients at the follow-up) there were two excellent and two good clinical results; radiologically all results were excellent. In four cancellous bone fixations redisplacement was noted. In all patients the functional score was 25.6/30 (Rasmussen 1973). The bioabsorbable implants can be used for fixation of proximal tibial cancellous bone osteotomies and fractures and avulsion fractures with good or moderate results.

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

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.

Totally absorbable fixation in the treatment of fractures of the distal femoral epiphyses. A prospective clinical study.

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.

Strength of the fixation of patellar tendon bone grafts using a totally absorbable self-reinforced poly-L-lactide expansion plug and screw. An experimental study in a bovine cadaver.

In a bovine cadaver study, bone-tendon-bone graft fixation strength with different graft geometry and fixation devices was measured to evaluate the fixation strength of totally absorbable implants: a 6.0-mm expansion plug and 6.3-mm screw both made of self-reinforced polylactide (SR-PLLA). Comparison was made with 6.5-mm AO cancellous screw. Maximum tensile force to dislodge the bone plug from the bone tunnel was recorded. First, two preliminary tests were performed. In the first test, triangular bone plugs were used (9-mm diameter). The direction of the pull force was parallel to the bone tunnel. The maximum tensile forces were 786 N in femoral insertions and 625 N in tibial insertions, mean. After this, we evaluated the influence of change in the pullout direction. In the second test, a circular bone plug was used with no fixation but the direction of the pull force was parallel to the tibial or femoral axis and the bone plug (10-mm diameter) was in a 30 degrees to 40 degrees angle to the direction of the pull force and it was compressed to the tunnel (9-mm diameter). The maximum tensile forces were 783 N in femoral insertions and 695 N in tibial insertions, mean. In the final third test, we used a curved saw in harvesting the graft. This made a half-circular bone block with a diameter of 12 mm. The maximum tensile force to dislodge the bone plug from the bone tunnel was recorded and the pull force was in a 30 degrees to 40 degrees angle to the tunnel. The results were evaluated with Student's t-test and Mann-Whitney U-test. With the AO screw, the maximum tensile force to dislodge the bone plug from the bone tunnel was 2,113 +/- 407 N (mean +/- standard deviation) and it was better than the fixation strength of the SR-PLLA expansion plug, 1,379 +/- 328 N (P = .009, t-test) and better than the fixation strength of SR-PLLA screw, 1,454 +/- 230 N (P = .007, t-test). However, the maximum tensile force of both SR-PLLA implants in all measurements in the third test were above 1,100 N and it seems that the initial strength of totally absorbable implants is enough for the clinical use.

[Changes in ulcer surgery following introduction of H2-blockers]. / Förändrad ulcuskirurgi efter introduktion av H2-blockerare.

To determine the effect of modern drug treatment on the incidence and type of ulcer operations, a retrospective survey was made of ulcer surgery performed on adult Helsinki residents during the years 1972, 1977, 1982 and 1987, with regard to indications and types of surgery. The introduction of H2-receptor blockers in 1979 was followed by a marked reduction in the incidence of elective ulcer surgery. On a population basis, the annual incidence of duodenal ulcer (DU) operations diminished by 50 per cent over the period 1972-1987, and that of operations for gastric ulcer by about two thirds, the falling trend being most marked among male DU patients. Figures for emergency surgical intervention in cases of haemorrhage or perforation remained unchanged during the period, as did the mean age of patients admitted for elective surgery, though the mean age of patients undergoing emergency surgery manifested a rising trend. The number of patients undergoing elective surgery for DU diminished, a trend first and foremost attributable to the fact that proximal selective vagotomy was performed more rarely, while the number of resections increased. The incidence of surgical treatment of pyloric and gastric ulcers remained unchanged during the period.

Peptic ulcer surgery during the H2-receptor antagonist era: a population-based epidemiological study of ulcer surgery in Helsinki from 1972 to 1987.

To evaluate the effects of improvements in medical therapy on the incidence of, indications for and operative methods used in peptic ulcer surgery, all cases of primary peptic ulcer surgery among adults in the city of Helsinki in the years 1972, 1977, 1982 and 1987 were analysed. There was a total of 565 such cases in a population which consisted of 5.2 X 10(5) individuals in 1972 and 4.8 X 10(5) individuals in 1987. The introduction of H2-receptor antagonists in 1979 was associated with a fall in the annual incidence of elective duodenal ulcer operations, from 15.5 to 6.7 per 10(5) individuals, and a fall in the annual incidence of elective gastric ulcer operations, from 9.4 to 3.1 per 10(5) individuals (P less than 0.05). The decrease was greatest among males with duodenal ulcer. In contrast, the annual incidence of emergency surgery for ulcer haemorrhage and perforation (all types of ulcers) remained relatively stable, varying from 7.2 to 10.2 per 10(5) inhabitants over the observation period (n.s.). The mean age of patients undergoing elective surgery remained essentially unchanged. The mean age of patients undergoing emergency surgery increased. The decrease in the annual incidence of elective duodenal ulcer surgery occurred mainly in relation to proximal gastric vagotomy. There was a concomitant relative increase in the incidence of gastric resection. The types of operative procedures used in cases of pyloric, prepyloric and gastric ulcer remained unchanged over the years 1972 to 1987.