Magnetic resonance imaging analysis of bioabsorbable interference screws used for fixation of bone-patellar tendon-bone autografts in endoscopic reconstruction of the anterior cruciate ligament.
BACKGROUND
Metal interference screws can cause problems if revision is needed and can interfere with magnetic resonance imaging. Bioabsorbable screws have been developed to prevent these problems, but the rate of resorption and integration is not well understood.


OBJECTIVE
Poly-L-lactic acid interference screws will be resorbed 2 years after anterior cruciate ligament reconstruction.


METHODS
Case series; Level of evidence, 4.


METHODS
The study group consisted of 19 patients with isolated anterior cruciate ligament ruptures reconstructed with bone-patellar tendon-bone autografts fixed with poly-L-lactic acid interference screws using an endoscopic technique. Magnetic resonance imaging was used to evaluate resorption of the screws, bony integration of the screws, and integration of the bone blocks after 2 years.


RESULTS
At 2 years, the mean reduction in the volume of the femoral screws was 64% and of the tibial screw was 63%. Bony integration of the femoral bone block was considered good in 17 patients and fair in 2 patients. Integration of the tibial bone block was considered good in 16 patients and fair in 1 patient who demonstrated widening of the tibial tunnel. Osteolysis around the screws was seen in 3 patients in the femur and none in the tibia.


CONCLUSIONS
The mean reduction in volume of the poly-L-lactic acid screws as measured by magnetic resonance imaging after 2 years was approximately two thirds. The integration of the bone blocks was considered good in 90% of the patients. Osteolysis around the screws was visible in 16% of the patients.


CONCLUSIONS
Two years after ACL reconstruction using poly-L-lactic acid interference screws, the surgeon can expect to find approximately one third of the volume of the screw remaining in the bone tunnels.
Department of Orthopaedics and Rheumatology, University Hospital Trondheim, Norway. Jon.O.Drogset@medisin.ntnu.no
Jon Olav
JO
Drogset
Torbjørn
T
Grøntvedt
Gunnar
G
Myhr
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods*; D001672:Biocompatible Materials; D001863:Bone Screws; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014182:Transplantation, Autologous
D001672:Biocompatible Materials