Comparative Analysis of Clinical and Biomechanical Outcomes of Manual Versus Motorized Drilling Techniques in Bone Tunnel Preparation for Anterior Cruciate Ligament Reconstruction

Background Anterior cruciate ligament (ACL) reconstruction is one of the most common orthopaedic procedures and represents the gold standard for restoring knee stability following rupture. While graft choice, tunnel placement, and fixation methods have been widely studied, the method of tunnel drilling has received little clinical attention. Motorized drilling, though precise, can cause thermal necrosis and trabecular compaction, potentially compromising tendon-to-bone healing. Manual drilling may preserve bone microarchitecture, thereby providing a more favorable environment for graft incorporation. Methods Forty patients undergoing ACL reconstruction were prospectively enrolled and divided into two groups. Twenty patients (mean age 14 years) underwent tunnel preparation with manual drilling using the Original All-Inside technique, while twenty patients (mean age 27 years) underwent conventional motorized drilling. Clinical outcomes were assessed at four months with the International Knee Documentation Committee (IKDC) subjective form and KT-1000 arthrometer. Biomechanical assessment included stabilometry on a force platform and three-dimensional gait analysis with force plates, motion capture, and surface electromyography. Results Manual drilling yielded higher IKDC scores (84.2 vs 81.6) and reduced anterior tibial translation (1.0 mm vs 1.4 mm). All patients in this group demonstrated ≤ 2 mm difference, compared with 67% in the motorized group. Stabilometry showed an increase in ellipse area from 175 to 215 mm² in the manual group and a decrease from 246 to 163 mm² in the motorized group. Gait analysis confirmed near-symmetric patterns in both groups, with slight decreases in symmetry correlation in the manual group (0.949→0.913) and increases in the motorized group (0.903→0.938). None of these differences were statistically significant. Conclusions Manual drilling provided superior early outcomes in subjective function and stability, consistent with preclinical findings that suggest enhanced tendon-to-bone healing. Although biomechanical results were similar, these preliminary clinical results highlight the potential biological benefits of manual drilling. Further randomized controlled trials with larger and age-matched cohorts are warranted.