Comparison of Tendon and Muscle-Tendon Semitendinosus Grafts After ACL Reconstruction

Comparison of Bone Ingrowth and Intra-articular Remodeling of Autologous Tendon and Muscle-tendon Semitendinosus Graft After Arthroscopic Anterior Cruciate Ligament Reconstruction Surgery

Aim: Comparison of tendon to bone ingrowth in bone tunnels and intra-articular remodeling of the graft after anterior cruciate ligament surgery with a muscle-tendon graft and those with a tendon graft. Subjects and methods: It is a single-blind prospective randomized study that would include at least 40 patients with an anterior cruciate ligament rupture. Patients would be randomly divided into two groups of minimally 20 patients each. Patients in the first study group would undergo ACL reconstruction with a muscle-tendon graft, while patients in the control group would be treated with the standard method of ACL reconstruction with a tendon graft.

Expected contribution to the field: The assumption is that the obtained results could enable a better understanding of the contribution of remaining muscle fibers on the tendon in anterior cruciate ligament reconstruction operations to the tendon to bone ingrowth and intra-articular remodeling of the graft of operated patients.

This is a prospective, randomized clinical study conducted at Dubrava University Hospital. At least 40 patients aged 18 to 50 years with clinically and MRI-confirmed anterior cruciate ligament rupture and indication for concomitant lateral tenodesis will be enrolled. Participants will be randomly assigned in a 1:1 ratio to undergo arthroscopic all-inside ACL reconstruction using either a muscle-tendon semitendinosus graft (experimental group) or a standard tendon-only semitendinosus graft (control group). All surgical procedures will be performed by the same surgeon and supplemented with modified Lemaire lateral tenodesis.

Clinical assessments will be performed preoperatively and at 6 weeks, 6 and 12 months postoperatively and will include validated patient-reported outcome measures (EQ-5D and KOOS) and a non-validated Croatian version of the IKDC Subjective Knee Evaluation Form. Knee stability will be assessed 12 months postoperatively using a digital Lachmeter device.

Magnetic resonance imaging of the operated knee will be performed at 6 weeks, 6 and 12 months using a standardized 3T MRI protocol including proton density sequences and T2 mapping. Intra-articular graft remodeling will be assessed using the signal-to-noise quotient method, with standardized regions of interest placed at the proximal, middle, and distal portions of the intra-articular graft and at the posterior cruciate ligament. Tendon-to-bone healing will be evaluated by measuring femoral and tibial tunnel diameters and calculating percentage tunnel widening relative to intraoperative tunnel size.

All participants will follow identical postoperative rehabilitation protocols. MRI analysis will be performed by two experienced musculoskeletal radiologists blinded to group allocation.

Inclusion Criteria:

• Clinically and radiologically confirmed anterior cruciate ligament (ACL) rupture.
• Age between 18 and 50 years.
• Intact posterior cruciate ligament and collateral ligaments.
• Signed informed consent to participate in the study.
• Patients meeting at least one indication for concomitant lateral tenodesis, including: age under 25 years, positive pivot-shift test, presence of Segond fracture, participation in sports with frequent changes of direction and rotational knee loads, or joint hypermobility (Beighton score ≥ 7).

Exclusion Criteria:

• Previous ACL reconstruction of the same knee.
• Inability to use a graft prepared by quadruple folding of the semitendinosus tendon.
• Graft diameter < 7.5 mm.
• MRI-confirmed unsuccessful meniscal healing after repair.
• Acute joint infection or history of joint infection.