Retrospective comparison of tunnelwidening (TW) after anterior cruciate ligament reconstruction in two surgery techniques and two biocomposite interference screws.

Bone tunnel enlargement or tunnel widening (TW) after anterior cruciate
ligament (ACL) reconstruction is well documented in the literature8. Although
many studies have described the presence of TW, none have shown this to be
clinically relevant, with respect to the graft or increased failure rates.1-6,
10 (ref from protocol). Despite this, the presence of enlarged tunnels can
complicate revision surgery. The exact etiology of TW is still unknown. Many
factors have been described, which can be divided in two categories: mechanical
and biological.
To get a better view of this mutifactorial problem, our purpose is to compare
the extent of TW between three different biocomposite interference screws (BIS)
in two different surgical techniques. We question whether differences in
material characteristics, composition of the screw materials and surgical
technique can influence the occurrence of TW after ACL reconstruction.

The aim of the study is to compare the radiological outcome of three different
biocomposite interference screws (BIS) in two different ACL-reconstruction
techniques with reference to TW, absorption and clinical follow up after three
years.

165 Patients will be asked to visit the hospital to get a clinical evaluation
and CT-images. They will also be asked to fill in specific questionaires to
evaluate clinical knee function the Knee Osteoarthritis Outcome Score (KOOS) an
International Knee Documentation Committee (IKDC). The Tegner score is used for
the level of activity.

For the patients the benefits of this study are a free physical examination and
evaluation of their complaints and CT-images.
Patients are asked to visit the hospital twice. If a patient is not mobile
enough or cannot reach the hospital for other reasons we will ask to visit them
at their home. Of these patients we will only be able to use the data from the
clinical examination and questionairs.
Radiation produced by conventional CT-imaging used in the present study is
negligible. Everybody living in a normal environment receives röntgen radiation
on a daily basis. This is called background radiation and it is expressed in
millisievert (mSv). There are potential risks related to radiation. Radiation
can cause immediate direct damage to body tissues (such as radiation burns and
hair loss), although usually only when given at higher doses. In this study
only low dose CT-imaging will be performed. Besides that we keep two important
keypoints in mind for medical radiation exposure: It has to be:
•*Justified* - exposure producing sufficient benefit to the exposed individual
to outweigh the potential risk of exposing to radiation15.
•*Optimised* - procedures and techniques should be in place to keep radiation
exposures as low as reasonably practical15.