Internal fixation in forefoot-surgery with resorbable implants
Common techniques of footsurgery were used in our series of 102 patients with
116 feet in conjunction with internal fixation with Lactosorb Biomet resorbable
polylactate screws and pins.
Following techniques were used:
Scarf and Akin osteotomy and soft-tissue repair as described by Weil and Barouk
for treatment of Hallux valgus. Instead of metallic screws lactosorb 2,5mm
screws where used. Attention was payed to secure fixation of the thread cuts in
the plantar corticalis.
Chevron osteotomies where done in a fashion with a long plantar arm.
Same techniques as used for the first ray have also been used for the fifth ray
for tailors bunion.
PIP arthrodesis or arthroplasty were performed using reunite pins for internal
fixation. Softtissue measures so as tendon lengthening or FDL transfer were
added when needed.
Metatasal osteotomies as described by Weil have been fixed with 2.0 lactosorb
Lactosorb Biomet is a copolymer for polylactate 82% and 18% polglcuconate. The
resorbtion time is anywhere around a year depending on location of implantation
and probably initial stability of the implant.
MATERIAL and METHODS
All operations were done by one surgeon starting in 2001.
All patients were prospectively examined and x-rayed at 6 weeks 12 weeks 6 month
and one year. The following numbers of the different types of operative
techniques were performed:
PIP 2-4 arthropasty n=94
Distal Weil Osteotomies n=50
Proximal Weil osteotomies n=4
M 5 Osteotomies n=5
All patients where immediately mobilised with full weight bearing with a stiff
soled postsurgical shoe (Darco) for 2 weeks with a insole with a cutout of the
first ray. The shoe was worne for another 2 to 4 weeks depending on the patients
Adverse reactions during time of observation:
We have not seen any signs of increased inflammatory response meaning redness,
increased swelling radiologic enlargement of the screw holes in first ray
surgery. Three patients reported discomfort over the screwheads between 6 and 12
month. Two were operated showing complete resorption of the screwheads at 8 and
10 month but with thickened connective tissue over the screwholes which were
still filled with disintegrated polylactate.
One of the patients a 28 year veterinary medicine doctor with a scarf osteotomy
of the 5th metatarsal showed disturbed primary wound healing, got antibiotics
from day five to 16. She developed frank deep infection at 8 weeks at the time
of increased hydrolysis of the screw material and was revised by an orthopaedic
surgeon in San Diego. He removed all the screw material and the wound healed
uneventfully under antibiotic coverage.
In one patient reoperated for transfermetatarsalgia 5 month after Weil
osteotomies no macroscopic screw material was found on or in the bone of the 3rd
metatarsal. My interpretation is: enhanced resorption in the presence of implant
Failure of fixation
Failure of fixation occurred in 2 chevron osteotomies within 3 days after
surgery because of vigorous use of the foot and inadaequate fixation of the one
lactosorb screw in the cancellous bone of the first metatarsal head.
2.0 lactosorb screws in distal Weil Oseotomies are positioned with there distal
part in cancellous bone and lack therefore the stability seen in cortical bone
fixation. Some of the patients with weilosteotomies showed increased callus
formation leading to disturbing prominences on the dorsum of the foot.
Radiologically healing with callus formation occurred with enlargement of the
screwholes. All of the osteotomies healed, some with callus formation some
without. Weil osteotomies stabilized with metallic implants heal typically
without callus formation.
Other complications without relation to the Lactosorb implant:
In the scarf group one heavy 250 pounds male patient showed proximal diaphyseal
fracture without failure of resorbable implant fixation. The fracture healed
with insignificant dislocation with plaster immobilisation.
The Kitaoka score at 6 month was 90. The total range of motion of the
metatarsophalangeal joints was 68°. 96% of the patients were subjectively
overall satisfied and would have this type of surgery again.
The radiological results showed following results:
- hallux valgus angle (Mitchel) preop 28° postop 9°
- intermatatarsal angle 1/2 (Mitchel) preop 11° postop 7°
- intermetatarsal angle 4/5: 9°/1°
- the tibial sesamoid position preop 5,6 postop 2,8.
- the metatarsal index 1/2 was : -0,69 preop and -0,97 mm post op
Scarf and longarm Chevron osteotomies can be safely fixed with 2,5 lactosorb
Biomet screws. The operating time is longer as compared to the technique with
threaded K-wires (Kinast et al 2002 ESFAS Sevilla). Weil osteotomies can be
stabilized with 2.0 lactosorb swrews, but this is preferably done with metallic
implants, because of the smaller diameter of metallic screws and threaded
K-wires and better holding strength in the cancellous bone. 2.0 lactosorb screws
work fine in M5 osteotomies in patients who do not want metallic implants.
Lactosorb pins add stability in hammertoe PIP-arthroplasties and obviate the use
of percutaneous K-wires, but the operating technique together with the stability
of the pins still needs further development. With the exception of one patient (infection) no adverse reactions could be observed with the use of lactosorb
Biomet resorbable implants in forefoot surgery.
Congress: AOFAS 19th Annual Summer Meeting - Hilton Head 27-Jun-2003
www.AOFAS.org (American Foot and Ankle Society)