Use of an Osteoconductive Scaffold in ACL-Reconstruction

CT based relative change of the femoral bone tunnel volume from baseline to follow-up 1 and 2.

International Knee Documentation Committee Subjective Knee Evaluation Form is designed to detect improvement or deterioration in symptoms, function and sports activities due to knee impairment for patients with a variety of knee conditions including ligament injuries. It is a patient-completed questionnaire available in multiple languages including German with an ordinal scoring system ranging from 0 (highest level of symptoms or lowest level of function) to 100 (no limitation with daily or sporting activities and the absence of symptoms).

To evaluate outcomes of knee ligament surgery, particularly symptoms of instability. It has an ordinal scoring system ranging from 0 to 100 (No symptoms or disability). A validated German version will be used.

The Tegner activity scale (TAS) is used to measure the change in physical activity from pre-injury to follow-up. Patient's activity is scored on a scale with 11 levels from level 0 (on sick leave/disability) to level 10 (participation in competitive sports such as soccer at a national or international elite level). Evaluated will be the difference in score from pre-injury (assessed at baseline visit) to follow-up.

The KT-1000 Arthrometer Test measures anterior displacement of the tibial plateau on the femur at a specific force. Its output variable is defined as the difference in full millimeters between the tibial displacement of the ACL reconstructed knee and the normal contralateral side.

The Lachman test measures anterior displacement conducted manually by the clinician. It is graded as the difference from the normal contralateral side as 0 (<3 mm), 1 (3 to 5 mm), or 2 (>5 mm).

The pivot shift test assesses the combined tibio-femoral rotation and anterior tibial translation. The pathologic motion elicited is graded as a glide (grade 1), clunk (grade 2), or gross clunk with locking (grade 3). A normal finding is graded as zero. The outcome measure is calculated from the difference between affected (repaired) and intact knee.

Bone tunnel width will additionally be assessed on plain radiograph. Standard posteroanterior radiographs of the knee in full extension will be used. Bone tunnel width will be assessed at the widest part of the femoral bone tunnel. Assessed will be the relative change in femoral bone tunnel width.

For a quantitative analysis of Osteoconductive scaffold (OCS)-bone integration, the mineral density profile along a predefined line will be examined. A slice showing the central portion of the OCS in the axial plane will be selected. A straight line of 2 cm length will be drawn perpendicular to the long axis of the OCS using image analysis software (Mimics). The CT-values along this line will be recorded and evaluated in the following way. Since the CT-values change according to the bone mineral density, the profile along the line will have a minimum at the interface of the tunnel wall and the OCS and a maximum on the OCS. The difference in Hounsfield units from the cancellous bone in the tunnel wall and the OCS-bone interface will be used as a measure for the degree of osseous integration of the implant.

Any occurrence of intra-operative complications will be recorded on the case report forms. Post-operative (serious) adverse events will be recorded at each follow-up visit.