SharkScrew ACL RCT

For the **ClinicalTrials.gov Detailed Description**, you generally want a more comprehensive description of the rationale, design, interventions, and objectives without reproducing the entire protocol. Here's a version suitable for direct use:

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**Detailed Description**

Anterior cruciate ligament (ACL) reconstruction is the standard surgical treatment for symptomatic ACL rupture, with interference screw fixation being the most commonly used method for tibial graft fixation. While current fixation techniques provide reliable mechanical stability, the optimal screw material remains uncertain. Commonly used polyetheretherketone (PEEK) screws are biologically inert and provide durable fixation but do not integrate with surrounding bone. Biocomposite screws are designed to gradually resorb while promoting bone ingrowth; however, their degradation characteristics have been associated with variable tunnel widening. More recently, allograft bone interference screws have been introduced as a biological alternative that may allow complete osseous incorporation while maintaining adequate initial fixation. Clinical evidence directly comparing these three fixation methods remains limited, particularly regarding their effects on tibial tunnel widening, graft incorporation, and patient outcomes.

This prospective, single-center, randomized controlled trial will compare tibial fixation using a PEEK screw, a biocomposite screw, or an allograft bone screw in patients undergoing primary ACL reconstruction. All participants will undergo reconstruction using a standardized SAMBBA technique with an ipsilateral quadriceps tendon autograft. Femoral fixation will be identical in all patients, with only the tibial interference screw differing between treatment groups. Participants will be randomized in a 1:1:1 allocation ratio using sealed envelopes. Patients, physiotherapists, and outcome assessors will remain blinded to treatment allocation throughout follow-up.

The primary endpoint is tibial tunnel widening measured on computed tomography (CT) 12 months after surgery. Secondary endpoints include graft incorporation assessed by magnetic resonance imaging (MRI) according to the method described by Putnis et al., as well as validated patient-reported outcome measures including the Lysholm Score, Tegner Activity Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), and ACL-Return to Sport after Injury (ACL-RSI). Clinical and radiographic follow-up will be performed according to the study schedule over 12 months after surgery.

The study is designed to determine whether allograft bone interference screws reduce tibial tunnel widening and improve biological graft integration compared with conventional PEEK and biocomposite screws while maintaining equivalent clinical outcomes. The findings are expected to provide high-quality evidence to guide the selection of tibial fixation devices in primary ACL reconstruction.

Inclusion criteria

• Male and non-pregnant female patients aged 18-70 years
• MRI-confirmed rupture of the anterior cruciate ligament (ACL)
• Clinically positive anterior drawer test and Lachman test
• Subjective instability
• Clinically and MRI-confirmed intact posterior cruciate ligament (PCL), medial collateral ligament (MCL), and posterolateral corner
• Written informed consent obtained
• Patient is able and willing to participate in the study

Exclusion criteria

• Previous surgery on the affected knee joint (ACL reconstruction, fracture fixation, osteotomy, or partial joint replacement)
• Body mass index (BMI) > 40
• Coronal instability due to injury of the medial collateral ligament or posterolateral corner
• Meniscal injury requiring postoperative restriction of weight-bearing (e.g., root tears, radial tears)
• The patient is unable to speak German
• The patient is pregnant