Hannu Pätiälä

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.

Outcome of clavicular fracture in 89 patients

SummaryDuring 1982, 118 patients with clavicular fracture were treated in the Department of Orthopaedics and Traumatology, Helsinki University Central Hospital. Eighty-nine patients appeared for the follow-up examination in 1984. Eighty-three fractures were treated with immobilization in a sling. Four fractures were treated with plate fixation primarily and two patients were operated on for delayed union. The immobilization averaged 21 days, range 10–42 days. The follow-up was 2 years in all cases. The result was good in 65 cases, satisfactory in 20, and poor in 4 cases. Patients with primary dislocation of more than 15 mm or with shortening observed at the follow-up examination had statistically significantly more pain than patients without these findings.ZusammenfassungAn der Orthopädisch-traumatologischen Klinik der Universität Helsinki wurden 1982 118 Patienten mit Klavikulafraktur behandelt. Neunundachtzig dieser Patienten konnten im Jahre 1984 nachuntersucht werden. Dreiundachtzig Frakturen waren durch Immobilisation im Armtragetuch behandelt worden. Vier Frakturen wurden primär verplattet, und zwei Fälle wurden wegen verzögerter Heilung sekundär operiert. Die Dauer der Immobilisation betrug durchschnittlich 21 Tage (10–42 Tage). Die Beobachtungszeit war in allen Fällen zwei Jahre. Das Ergebnis der Behandlung war gut in 65 Fällen, befriedigend in 20 Fällen und schlecht in 4 Fällen. Patienten mit primärer Dislokation von mehr als 15 mm oder bei der Nachuntersuchung festgestellter Verkürzung hatten signifikant mehr Schmerzen als Patienten ohne derartige Befunde.

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

Summary 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.

Importance of Anatomical Reduction for Subjective Recovery After Ankle Fracture

237 patients with ankle fractures treated during 1977 were evaluated with the object of studying the treatment results and the factors influencing the results. About one half of the patients were treated conservatively and the other half operatively. The type of treatment was determined by the type of injury; hence the milder injuries were usually treated conservatively and the more severe cases operatively. A good radiological primary result was obtained in 82 per cent of the malleoli with operative treatment and in 34 per cent with conservative treatment. The evaluation of the end-result was based on a questionnaire study made 1.5-2.5 years after the accident. All those employed before their injuries had returned to their previous occupations. 27 per cent of the patients responded that they had recovered completely. The subjective end-result was found to correlate with the radiological result at the end of the treatment, but not with the type of injury, the type of treatment, or the patients age.

Radial palsy in shaft fracture of the humerus

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.

Surgery for ununited clavicular fracture

Twenty-four ununited, primarily conservatively treated clavicular fractures were treated operatively. The follow-up period averaged 3.5 years. In all cases, the primary displacement was at least equal to the clavicular thickness. The subjective outcome was good in 17 cases, satisfactory in six, and poor in one. In two cases, resection was performed. Our experience of rigid plate fixation and cancellous bone grafting was good with union in 20/22 cases. However, the operations are not uncomplicated and there is a risk of diminished muscle power and range of movement in the shoulder if the clavicle is shortened.

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

SummaryOsteotomies 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.

Internal fixation of forearm fractures in children

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.

Strength retention of self-reinforced poly-L-lactide screws. A comparison of compression moulded and machine cut screws.

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.

Shear strength of cancellous bone after osteotomy fixed with absorbable self-reinforced polyglycolic acid and poly-L-lactic acid rods

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.