Use of an Osteoconductive Scaffold in ACL-Reconstruction (ACLROCS)

Primary objective of the study is to evaluate efficacy of the surgical technique for ACL reconstruction using an osteoconductive scaffold, enlaced into the hamstring tendon autograft, compared to the traditional technique.

Reconstruction of the anterior cruciate ligament (ACL) using autograft tissue is currently recommended as the standard of care following an ACL tear or rupture, with the bone-tendon-bone (BTB) graft and hamstring tendon graft the most common. Although a BTB autograft is widely recognized to offer high mechanical performance and rapid graft healing, these advantages come at the cost of a longer surgery time and higher risk of severe patient discomfort at the graft harvest site. Use of a hamstring tendon autograft is less painful, but is generally slower to heal with higher risk of mechanical graft failure due to poor bone ingrowth. The aim of the current study is to augment graft-to-bone incorporation by use of an osteoconductive scaffold enlaced into the hamstring tendon autograft. This bovine derived composite bone substitute is inserted into the articular aperture of the femoral bone tunnel and should provide an osteoconductive / osteoinductive environment at a biomimetic attachment site leading to improved secondary graft-fixation and a reduced incidence of tunnel widening. Primary objective of the study is to evaluate efficacy of the surgical technique for ACL reconstruction using an osteoconductive scaffold, enlaced into the hamstring tendon autograft, compared to the traditional technique. Secondary objectives aim to assess the clinical outcome of the interventional treatment including patient subjective knee function and objective measures of knee stability.

ACL-reconstruction using hamstring autograft with hybrid fixation in accordance with in-house standard of care.

ACL-reconstruction using hamstring autograft with hybrid fixation combined with the osteoconductive device under study.

The device under study is a composite bone substitute composed of a natural mineral matrix of bovine origin, reinforced with biodegradable synthetic polymers and natural collagen derivatives of bovine origin (smartbone, IBI S.A., Switzerland).

ACL-reconstruction using hamstring autograft with hybrid fixation in accordance with in-house standard of care.

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.

Inclusion Acute unilateral complete tear of the ACL that occurred within 18 weeks before planned surgery and requires reconstruction of the Informed consent as documented by signature Exclusion Criteria: Prior ACL reconstruction or other surgical procedure on the affected knee. Prior fracture of the affected leg. Multi-ligament reconstruction. Previous or current ACL injury on contra-lateral leg. Medical condition or comorbidity that would interfere with study participation. The patient is mentally compromised. Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant. Other clinically significant concomitant disease states (e.g. renal failure, hepatic dysfunction, cardiovascular disease, etc.).