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

Comparative Analysis of Clinical and Biomechanical Outcomes of Manual Versus Motorized Drilling Techniques in Bone Tunnel Preparation for Anterior Cruciate Ligament Reconstruction | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparative Analysis of Clinical and Biomechanical Outcomes of Manual Versus Motorized Drilling Techniques in Bone Tunnel Preparation for Anterior Cruciate Ligament Reconstruction Matteo Maria Tei, Davide Palmieri, Zorba Enxhi, Roberto Tiribuzi, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8278664/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract 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. Figures Figure 1 Figure 2 Figure 3 Introduction Anterior cruciate ligament (ACL) rupture is among the most prevalent injuries in orthopaedic and sports medicine, particularly within young and physically active populations. The ACL plays a critical role in stabilizing the knee joint by resisting anterior tibial translation and rotational forces. Injury to this structure can have profound consequences, including knee instability, reduced athletic performance, and increased risk of subsequent meniscal and chondral damage, ultimately predisposing patients to early-onset osteoarthritis. Epidemiological reports estimate more than 250,000 ACL injuries occur annually in the United States, of which over 100,000 undergo surgical reconstruction each year (1). The societal burden is significant, not only because of direct surgical costs, but also due to time lost from work, sports participation, and long-term rehabilitation. Despite substantial progress in surgical methods, graft technology, and rehabilitation strategies, outcomes following ACL reconstruction remain variable. Failure rates ranging from 5–15% have been reported, while persistent instability and subjective dissatisfaction occur in up to 20% of patients (2–4). Multiple factors influence surgical success, including patient selection, timing of surgery, surgical technique, graft choice, tunnel placement accuracy, fixation methods, and—importantly—the biological process of tendon-to-bone healing (5–7). Graft type has historically been a central focus of research. Bone–patellar tendon–bone (BPTB) autografts, long considered the gold standard, demonstrate robust bone-to-bone integration, resulting in relatively rapid healing within bone tunnels. However, donor-site morbidity, anterior knee pain, and risk of patellar fracture or tendinopathy remain significant concerns (8,9). Hamstring tendon grafts, increasingly favored due to less invasive harvesting and reduced donor-site complications, present their own challenges. These grafts require soft tissue–to–bone healing, which progresses more slowly than bone-to-bone integration and may represent a biomechanical weak point during the early postoperative phase (10,11). Among the technical factors influencing graft healing, tunnel preparation has received comparatively less attention in the clinical literature. Traditionally, motorized drilling has been the standard technique, offering efficiency, reproducibility, and precision. Nevertheless, experimental data demonstrate that high-speed drilling generates considerable frictional heat, which can raise bone temperatures above 47°C, a threshold beyond which thermal necrosis occurs (12–14). Necrotic bone at the tunnel interface compromises graft integration and weakens early fixation. In addition, the high rotational forces of powered drills compact trabecular bone, reducing porosity and thereby restricting vascular ingrowth, cellular migration, and subsequent osteointegration (15). Manual drilling has been proposed as a biologically favorable alternative. By relying on hand-driven instruments, this technique reduces frictional heat generation, preserving bone vitality and avoiding thermal necrosis. Furthermore, manual drilling minimizes trabecular compaction, maintaining open vascular channels and bone microarchitecture that may facilitate angiogenesis and fibrocartilage formation—critical steps in the tendon-to-bone healing cascade (16,17). In animal studies, Cerulli et al. demonstrated that manual drilling preserved trabecular integrity and promoted improved fibrocartilage formation in a rabbit ACL reconstruction model (18). However, to date, clinical evidence directly comparing manual and motorized drilling techniques remains limited, and the potential translational benefits of manual drilling for human ACL reconstruction require systematic evaluation. The present study was designed to address this gap. We conducted a prospective comparative analysis of early clinical and biomechanical outcomes following ACL reconstruction performed using manual versus motorized drilling techniques. Our primary hypothesis was that manual drilling would result in superior joint stability and subjective function due to more favorable biological conditions for tendon-to-bone healing. Secondary outcomes included balance control and gait parameters, measured through stabilometry and motion analysis. By combining clinical, functional, and biomechanical assessments, this study aimed to provide a comprehensive evaluation of the impact of tunnel preparation technique on short-term recovery after ACL reconstruction. Materials and Methods Study Design and Patient Population This prospective comparative study was conducted at a single academic institution between January 2023 and June 2024. A total of 40 patients undergoing primary ACL reconstruction were enrolled consecutively. Ethical approval was obtained from the institutional review board, and all participants provided written informed consent prior to inclusion. Patients were allocated into two groups based on tunnel preparation method. The manual drilling group consisted of 20 patients (12 males, 8 females; mean age 14 years, range 13–16 years), while the motorized drilling group included 20 patients (10 males, 10 females; mean age 27 years, range 22–33 years). Assignment to groups was not randomized, as manual drilling was preferentially offered to skeletally immature patients. Exclusion criteria were: concomitant meniscal repair, presence of significant chondral injury, multi-ligamentous injuries, history of previous ipsilateral knee surgery, systemic bone disorders, or inability to comply with postoperative rehabilitation. Surgical Technique All procedures were performed by two senior orthopaedic surgeons experienced in both manual and motorized techniques. Manual drilling group : ACL reconstruction was performed using the Original All-Inside technique. Both femoral and tibial tunnels were created with a hand-controlled device, allowing gradual progression through trabecular bone while minimizing heat generation. Grafts consisted of tripled or quadrupled semitendinosus or gracilis tendons, depending on availability and diameter. Motorized drilling group : Standard high-speed motorized drills were used for tunnel creation, with identical graft choices (tripled/quadrupled hamstring tendons). Tunnel placement was guided arthroscopically, ensuring anatomic positioning in both groups. Fixation devices were standardized across both groups, consisting of suspensory cortical buttons on the femoral side and bioabsorbable interference screws on the tibial side. Rehabilitation Protocol Rehabilitation Protocol Postoperative rehabilitation was standardized for all participants. Early emphasis was placed on pain control, swelling reduction, and restoration of full extension. Partial weight-bearing with crutches was permitted immediately, progressing to full weight-bearing as tolerated within the first two weeks. Closed-chain strengthening exercises began at 3 weeks, with jogging permitted at 3 months and sport-specific drills after 5–6 months, contingent on recovery progress. Clinical Assessment Clinical outcomes were measured at 4 months postoperatively. Subjective knee function was assessed using the International Knee Documentation Committee (IKDC) subjective knee score (19). Objective stability was evaluated using the KT-1000 arthrometer (20), measuring side-to-side anterior tibial translation at 134 N of force. A side-to-side difference ≤ 2 mm was considered clinically acceptable. Biomechanical Evaluation To complement clinical outcomes, biomechanical performance was assessed through: Stabilometry : Static balance was evaluated using a force platform, recording center-of-pressure sway and ellipse area (21). Gait Analysis : Performed in a motion analysis laboratory, gait parameters were assessed using a 3D motion capture system, synchronized force plates, and surface electromyography (22). Bilateral correlation coefficients were calculated to determine gait symmetry. Statistical Analysis Data were analyzed using descriptive and inferential statistics. Continuous variables were reported as means with standard deviations, while categorical data were presented as frequencies and percentages. Between-group differences were assessed using independent t-tests for continuous variables and chi-square tests for categorical variables. A p-value < 0.05 was considered statistically significant. Results Clinical Outcomes At 4-month follow-up, the manual drilling group demonstrated higher mean IKDC scores (84.2 ± 6.1) compared with the motorized drilling group (81.6 ± 7.4). Although the difference did not reach statistical significance (p = 0.09), the trend favored manual drilling. Objective anterior stability measured by KT-1000 arthrometer showed a mean side-to-side difference of 1.0 ± 0.4 mm in the manual group versus 1.4 ± 0.6 mm in the motorized group (p = 0.07). Importantly, all patients in the manual group achieved stability thresholds of ≤ 2 mm, whereas only 67% of patients in the motorized group met this benchmark. Biomechanical Findings Stabilometric analysis revealed divergent trajectories between groups. The manual group demonstrated an increase in ellipse area from 175 mm² to 215 mm², interpreted as greater postural adaptability and improved balance control. Conversely, the motorized group exhibited a reduction from 246 mm² to 163 mm², suggestive of more rigid postural strategies. Gait analysis revealed nearly symmetric patterns in both groups. In the manual group, bilateral correlation coefficients decreased slightly from 0.949 to 0.913, whereas the motorized group improved from 0.903 to 0.938. These results indicate minor group differences but broadly similar gait recovery trajectories. Complications No intraoperative complications occurred in either group. One patient in the motorized drilling group experienced transient knee effusion requiring aspiration. No graft failures or revisions were reported at 4 months. Discussion The principal finding of this study is that manual drilling may confer early clinical advantages in ACL reconstruction, particularly with respect to subjective outcomes and knee stability. Patients undergoing manual drilling reported higher IKDC scores and demonstrated superior KT-1000 stability compared with those treated with motorized drilling, although differences did not reach statistical significance due to limited sample size. Biomechanical assessments revealed broadly similar outcomes, with subtle variations favoring manual drilling in balance but motorized drilling in gait symmetry. Biological Rationale These findings align with preclinical evidence highlighting the deleterious effects of thermal injury during tunnel preparation. Matthews and Hirsch (12) first demonstrated that powered drilling generates temperatures exceeding thresholds for bone necrosis. Eriksson and Albrektsson (14) further quantified this relationship, identifying 47°C as the critical temperature above which irreversible osteocyte death occurs. Necrotic bone lacks the capacity to remodel and integrate, thereby delaying tendon-to-bone healing. Additionally, compaction of trabecular bone by motorized drilling reduces porosity, impairing vascular infiltration and cellular migration (15). Manual drilling circumvents these issues. By generating minimal heat and preserving trabecular microarchitecture, manual drilling maintains the biological environment necessary for angiogenesis, collagen fiber orientation, and fibrocartilage formation. The animal studies of Cerulli et al. (18) provide histological confirmation, demonstrating enhanced fibrocartilage formation and improved tendon-to-bone integration following manual drilling compared with powered techniques. Clinical Implications The clinical implications of these findings are noteworthy, particularly in skeletally immature patients. Adolescents have heightened biological potential for healing due to increased vascularity and bone remodeling capacity. Techniques that preserve bone vitality may further enhance outcomes in this vulnerable population. Moreover, the reduced mechanical trauma associated with manual drilling may lower the risk of tunnel widening, a phenomenon associated with graft laxity and failure in the long term. From a rehabilitation perspective, earlier stability and improved subjective function may translate into greater confidence, faster progression through rehabilitation milestones, and potentially earlier return to sport. While our short-term follow-up precludes definitive conclusions regarding return-to-play timelines, the observed trends suggest manual drilling may positively influence these outcomes. Limitations Several limitations must be acknowledged. First, the study sample size was small, limiting statistical power to detect differences between groups. Second, allocation was not randomized; manual drilling was preferentially used in younger patients, introducing potential confounding by age and biological healing capacity. Third, follow-up was limited to 4 months, capturing only early outcomes and not long-term endpoints such as tunnel widening, graft remodeling, or return to sport. Fourth, the study did not include imaging or histological analysis, which would provide direct evidence of biological integration at the tendon-to-bone interface. Future Directions Future research should focus on larger, randomized controlled trials with age-matched cohorts to eliminate potential confounding. Longitudinal follow-up is necessary to evaluate whether early advantages in stability and function persist over time and translate into improved return-to-sport rates and reduced graft failure. Advanced imaging modalities, such as MRI, CT, and even PET-CT, may provide insights into biological integration, vascularity, and metabolic activity within tunnels. Additionally, future studies could explore the integration of manual drilling with emerging techniques, including biologic augmentation (e.g., platelet-rich plasma, stem cells) and biomaterial scaffolds designed to accelerate tendon-to-bone healing. Conclusion This prospective comparative study suggests that manual drilling in ACL reconstruction may provide early clinical benefits compared with motorized drilling. Patients undergoing manual drilling demonstrated superior subjective knee function and joint stability, while balance and gait outcomes were broadly comparable between groups. Although differences did not reach statistical significance, the consistent direction of findings supports the biological rationale for manual drilling, namely reduced thermal injury and preservation of trabecular architecture. Given the limitations of small sample size and short-term follow-up, these findings should be interpreted cautiously. Nevertheless, manual drilling represents a biologically sound technique that may hold particular promise in skeletally immature populations. Larger, randomized, and long-term studies are required to confirm these preliminary results and to establish the role of manual drilling as a standard or adjunctive technique in ACL reconstruction. Declarations Founding no founding was received by any of the authors . Conflict of interest: The authors declare no conflict of interests. Ethics approval : This study was conducted in adherence to the international principles of the Declaration of Helsinki. Informed consent was obtained from all participants, and the research was approved by the Institutional Ethics Committee of a university-affiliated research center. Author Contribution All authors whose names appear on the submission made substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data; or the creation of new software used in the work;drafted the work or revised it critically for important intellectual content;approved the version to be published; andagree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Data availability: No datasets were generated or analysed during the current study. References Griffin LY, Agel J, Albohm MJ, et al. Noncontact ACL injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8(3):141–150. Shelbourne KD, Trumper RV. Preventing anterior knee pain after ACL reconstruction. Am J Sports Med. 1997;25(1):41–47. Rodeo SA, Arnoczky SP, Torzilli PA, Hidaka C, Warren RF. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8278664","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":559426504,"identity":"3494ee1a-6731-4107-b261-b355696393e0","order_by":0,"name":"Matteo Maria 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12:41:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":702610,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8278664/v1/c55634f9-1ea4-4ecd-aad7-e88a55957b70.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparative Analysis of Clinical and Biomechanical Outcomes of Manual Versus Motorized Drilling Techniques in Bone Tunnel Preparation for Anterior Cruciate Ligament Reconstruction","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAnterior cruciate ligament (ACL) rupture is among the most prevalent injuries in orthopaedic and sports medicine, particularly within young and physically active populations. The ACL plays a critical role in stabilizing the knee joint by resisting anterior tibial translation and rotational forces. Injury to this structure can have profound consequences, including knee instability, reduced athletic performance, and increased risk of subsequent meniscal and chondral damage, ultimately predisposing patients to early-onset osteoarthritis. Epidemiological reports estimate more than 250,000 ACL injuries occur annually in the United States, of which over 100,000 undergo surgical reconstruction each year (1). The societal burden is significant, not only because of direct surgical costs, but also due to time lost from work, sports participation, and long-term rehabilitation.\u003c/p\u003e \u003cp\u003eDespite substantial progress in surgical methods, graft technology, and rehabilitation strategies, outcomes following ACL reconstruction remain variable. Failure rates ranging from 5\u0026ndash;15% have been reported, while persistent instability and subjective dissatisfaction occur in up to 20% of patients (2\u0026ndash;4). Multiple factors influence surgical success, including patient selection, timing of surgery, surgical technique, graft choice, tunnel placement accuracy, fixation methods, and\u0026mdash;importantly\u0026mdash;the biological process of tendon-to-bone healing (5\u0026ndash;7).\u003c/p\u003e \u003cp\u003eGraft type has historically been a central focus of research. Bone\u0026ndash;patellar tendon\u0026ndash;bone (BPTB) autografts, long considered the gold standard, demonstrate robust bone-to-bone integration, resulting in relatively rapid healing within bone tunnels. However, donor-site morbidity, anterior knee pain, and risk of patellar fracture or tendinopathy remain significant concerns (8,9). Hamstring tendon grafts, increasingly favored due to less invasive harvesting and reduced donor-site complications, present their own challenges. These grafts require soft tissue\u0026ndash;to\u0026ndash;bone healing, which progresses more slowly than bone-to-bone integration and may represent a biomechanical weak point during the early postoperative phase (10,11).\u003c/p\u003e \u003cp\u003eAmong the technical factors influencing graft healing, tunnel preparation has received comparatively less attention in the clinical literature. Traditionally, motorized drilling has been the standard technique, offering efficiency, reproducibility, and precision. Nevertheless, experimental data demonstrate that high-speed drilling generates considerable frictional heat, which can raise bone temperatures above 47\u0026deg;C, a threshold beyond which thermal necrosis occurs (12\u0026ndash;14). Necrotic bone at the tunnel interface compromises graft integration and weakens early fixation. In addition, the high rotational forces of powered drills compact trabecular bone, reducing porosity and thereby restricting vascular ingrowth, cellular migration, and subsequent osteointegration (15).\u003c/p\u003e \u003cp\u003eManual drilling has been proposed as a biologically favorable alternative. By relying on hand-driven instruments, this technique reduces frictional heat generation, preserving bone vitality and avoiding thermal necrosis. Furthermore, manual drilling minimizes trabecular compaction, maintaining open vascular channels and bone microarchitecture that may facilitate angiogenesis and fibrocartilage formation\u0026mdash;critical steps in the tendon-to-bone healing cascade (16,17). In animal studies, Cerulli et al. demonstrated that manual drilling preserved trabecular integrity and promoted improved fibrocartilage formation in a rabbit ACL reconstruction model (18). However, to date, clinical evidence directly comparing manual and motorized drilling techniques remains limited, and the potential translational benefits of manual drilling for human ACL reconstruction require systematic evaluation.\u003c/p\u003e \u003cp\u003eThe present study was designed to address this gap. We conducted a prospective comparative analysis of early clinical and biomechanical outcomes following ACL reconstruction performed using manual versus motorized drilling techniques. Our primary hypothesis was that manual drilling would result in superior joint stability and subjective function due to more favorable biological conditions for tendon-to-bone healing. Secondary outcomes included balance control and gait parameters, measured through stabilometry and motion analysis. By combining clinical, functional, and biomechanical assessments, this study aimed to provide a comprehensive evaluation of the impact of tunnel preparation technique on short-term recovery after ACL reconstruction.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Patient Population\u003c/h2\u003e \u003cp\u003eThis prospective comparative study was conducted at a single academic institution between January 2023 and June 2024. A total of 40 patients undergoing primary ACL reconstruction were enrolled consecutively. Ethical approval was obtained from the institutional review board, and all participants provided written informed consent prior to inclusion.\u003c/p\u003e \u003cp\u003ePatients were allocated into two groups based on tunnel preparation method. The \u003cb\u003emanual drilling group\u003c/b\u003e consisted of 20 patients (12 males, 8 females; mean age 14 years, range 13\u0026ndash;16 years), while the \u003cb\u003emotorized drilling group\u003c/b\u003e included 20 patients (10 males, 10 females; mean age 27 years, range 22\u0026ndash;33 years). Assignment to groups was not randomized, as manual drilling was preferentially offered to skeletally immature patients.\u003c/p\u003e \u003cp\u003e Exclusion criteria were: concomitant meniscal repair, presence of significant chondral injury, multi-ligamentous injuries, history of previous ipsilateral knee surgery, systemic bone disorders, or inability to comply with postoperative rehabilitation.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurgical Technique\u003c/h3\u003e\n\u003cp\u003eAll procedures were performed by two senior orthopaedic surgeons experienced in both manual and motorized techniques.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eManual drilling group\u003c/b\u003e: ACL reconstruction was performed using the Original All-Inside technique. Both femoral and tibial tunnels were created with a hand-controlled device, allowing gradual progression through trabecular bone while minimizing heat generation. Grafts consisted of tripled or quadrupled semitendinosus or gracilis tendons, depending on availability and diameter.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eMotorized drilling group\u003c/b\u003e: Standard high-speed motorized drills were used for tunnel creation, with identical graft choices (tripled/quadrupled hamstring tendons). Tunnel placement was guided arthroscopically, ensuring anatomic positioning in both groups.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eFixation devices were standardized across both groups, consisting of suspensory cortical buttons on the femoral side and bioabsorbable interference screws on the tibial side.\u003c/p\u003e\n\u003ch3\u003eRehabilitation Protocol\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eRehabilitation Protocol\u003c/div\u003e \u003cp\u003ePostoperative rehabilitation was standardized for all participants. Early emphasis was placed on pain control, swelling reduction, and restoration of full extension. Partial weight-bearing with crutches was permitted immediately, progressing to full weight-bearing as tolerated within the first two weeks. Closed-chain strengthening exercises began at 3 weeks, with jogging permitted at 3 months and sport-specific drills after 5\u0026ndash;6 months, contingent on recovery progress.\u003c/p\u003e\n\u003ch3\u003eClinical Assessment\u003c/h3\u003e\n\u003cp\u003eClinical outcomes were measured at 4 months postoperatively. Subjective knee function was assessed using the International Knee Documentation Committee (IKDC) subjective knee score (19). Objective stability was evaluated using the KT-1000 arthrometer (20), measuring side-to-side anterior tibial translation at 134 N of force. A side-to-side difference\u0026thinsp;\u0026le;\u0026thinsp;2 mm was considered clinically acceptable.\u003c/p\u003e\n\u003ch3\u003eBiomechanical Evaluation\u003c/h3\u003e\n\u003cp\u003eTo complement clinical outcomes, biomechanical performance was assessed through:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eStabilometry\u003c/b\u003e: Static balance was evaluated using a force platform, recording center-of-pressure sway and ellipse area (21).\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eGait Analysis\u003c/b\u003e: Performed in a motion analysis laboratory, gait parameters were assessed using a 3D motion capture system, synchronized force plates, and surface electromyography (22). Bilateral correlation coefficients were calculated to determine gait symmetry.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using descriptive and inferential statistics. Continuous variables were reported as means with standard deviations, while categorical data were presented as frequencies and percentages. Between-group differences were assessed using independent t-tests for continuous variables and chi-square tests for categorical variables. A p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eClinical Outcomes\u003c/h2\u003e \u003cp\u003eAt 4-month follow-up, the manual drilling group demonstrated higher mean IKDC scores (84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1) compared with the motorized drilling group (81.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4). Although the difference did not reach statistical significance (p\u0026thinsp;=\u0026thinsp;0.09), the trend favored manual drilling.\u003c/p\u003e \u003cp\u003eObjective anterior stability measured by KT-1000 arthrometer showed a mean side-to-side difference of 1.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 mm in the manual group versus 1.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 mm in the motorized group (p\u0026thinsp;=\u0026thinsp;0.07). Importantly, all patients in the manual group achieved stability thresholds of \u0026le;\u0026thinsp;2 mm, whereas only 67% of patients in the motorized group met this benchmark.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eBiomechanical Findings\u003c/h2\u003e \u003cp\u003eStabilometric analysis revealed divergent trajectories between groups. The manual group demonstrated an increase in ellipse area from 175 mm\u0026sup2; to 215 mm\u0026sup2;, interpreted as greater postural adaptability and improved balance control. Conversely, the motorized group exhibited a reduction from 246 mm\u0026sup2; to 163 mm\u0026sup2;, suggestive of more rigid postural strategies.\u003c/p\u003e \u003cp\u003eGait analysis revealed nearly symmetric patterns in both groups. In the manual group, bilateral correlation coefficients decreased slightly from 0.949 to 0.913, whereas the motorized group improved from 0.903 to 0.938. These results indicate minor group differences but broadly similar gait recovery trajectories.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eComplications\u003c/h2\u003e \u003cp\u003eNo intraoperative complications occurred in either group. One patient in the motorized drilling group experienced transient knee effusion requiring aspiration. No graft failures or revisions were reported at 4 months.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe principal finding of this study is that manual drilling may confer early clinical advantages in ACL reconstruction, particularly with respect to subjective outcomes and knee stability. Patients undergoing manual drilling reported higher IKDC scores and demonstrated superior KT-1000 stability compared with those treated with motorized drilling, although differences did not reach statistical significance due to limited sample size. Biomechanical assessments revealed broadly similar outcomes, with subtle variations favoring manual drilling in balance but motorized drilling in gait symmetry.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eBiological Rationale\u003c/h2\u003e \u003cp\u003eThese findings align with preclinical evidence highlighting the deleterious effects of thermal injury during tunnel preparation. Matthews and Hirsch (12) first demonstrated that powered drilling generates temperatures exceeding thresholds for bone necrosis. Eriksson and Albrektsson (14) further quantified this relationship, identifying 47\u0026deg;C as the critical temperature above which irreversible osteocyte death occurs. Necrotic bone lacks the capacity to remodel and integrate, thereby delaying tendon-to-bone healing. Additionally, compaction of trabecular bone by motorized drilling reduces porosity, impairing vascular infiltration and cellular migration (15).\u003c/p\u003e \u003cp\u003eManual drilling circumvents these issues. By generating minimal heat and preserving trabecular microarchitecture, manual drilling maintains the biological environment necessary for angiogenesis, collagen fiber orientation, and fibrocartilage formation. The animal studies of Cerulli et al. (18) provide histological confirmation, demonstrating enhanced fibrocartilage formation and improved tendon-to-bone integration following manual drilling compared with powered techniques.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eClinical Implications\u003c/h2\u003e \u003cp\u003eThe clinical implications of these findings are noteworthy, particularly in skeletally immature patients. Adolescents have heightened biological potential for healing due to increased vascularity and bone remodeling capacity. Techniques that preserve bone vitality may further enhance outcomes in this vulnerable population. Moreover, the reduced mechanical trauma associated with manual drilling may lower the risk of tunnel widening, a phenomenon associated with graft laxity and failure in the long term.\u003c/p\u003e \u003cp\u003eFrom a rehabilitation perspective, earlier stability and improved subjective function may translate into greater confidence, faster progression through rehabilitation milestones, and potentially earlier return to sport. While our short-term follow-up precludes definitive conclusions regarding return-to-play timelines, the observed trends suggest manual drilling may positively influence these outcomes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eSeveral limitations must be acknowledged. First, the study sample size was small, limiting statistical power to detect differences between groups. Second, allocation was not randomized; manual drilling was preferentially used in younger patients, introducing potential confounding by age and biological healing capacity. Third, follow-up was limited to 4 months, capturing only early outcomes and not long-term endpoints such as tunnel widening, graft remodeling, or return to sport. Fourth, the study did not include imaging or histological analysis, which would provide direct evidence of biological integration at the tendon-to-bone interface.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eFuture Directions\u003c/h2\u003e \u003cp\u003eFuture research should focus on larger, randomized controlled trials with age-matched cohorts to eliminate potential confounding. Longitudinal follow-up is necessary to evaluate whether early advantages in stability and function persist over time and translate into improved return-to-sport rates and reduced graft failure. Advanced imaging modalities, such as MRI, CT, and even PET-CT, may provide insights into biological integration, vascularity, and metabolic activity within tunnels. Additionally, future studies could explore the integration of manual drilling with emerging techniques, including biologic augmentation (e.g., platelet-rich plasma, stem cells) and biomaterial scaffolds designed to accelerate tendon-to-bone healing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis prospective comparative study suggests that manual drilling in ACL reconstruction may provide early clinical benefits compared with motorized drilling. Patients undergoing manual drilling demonstrated superior subjective knee function and joint stability, while balance and gait outcomes were broadly comparable between groups. Although differences did not reach statistical significance, the consistent direction of findings supports the biological rationale for manual drilling, namely reduced thermal injury and preservation of trabecular architecture.\u003c/p\u003e \u003cp\u003eGiven the limitations of small sample size and short-term follow-up, these findings should be interpreted cautiously. Nevertheless, manual drilling represents a biologically sound technique that may hold particular promise in skeletally immature populations. Larger, randomized, and long-term studies are required to confirm these preliminary results and to establish the role of manual drilling as a standard or adjunctive technique in ACL reconstruction.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eFounding\u003c/strong\u003e \u003cp\u003eno founding was received by any of the authors .\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eConflict of interest:\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict of interests.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003e \u003cb\u003eEthics approval\u003c/b\u003e:\u003c/strong\u003e \u003cp\u003e This study was conducted in adherence to the international principles of the Declaration of Helsinki. Informed consent was obtained from all participants, and the research was approved by the Institutional Ethics Committee of a university-affiliated research center.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors whose names appear on the submission made substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data; or the creation of new software used in the work;drafted the work or revised it critically for important intellectual content;approved the version to be published; andagree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.\u003c/p\u003e\u003ch2\u003eData availability:\u003c/h2\u003e \u003cp\u003eNo datasets were generated or analysed during the current study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGriffin LY, Agel J, Albohm MJ, et al. Noncontact ACL injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8(3):141\u0026ndash;150.\u003c/li\u003e\n\u003cli\u003eShelbourne KD, Trumper RV. Preventing anterior knee pain after ACL reconstruction. Am J Sports Med. 1997;25(1):41\u0026ndash;47.\u003c/li\u003e\n\u003cli\u003eRodeo SA, Arnoczky SP, Torzilli PA, Hidaka C, Warren RF. Tendon-to-bone healing after ACL reconstruction. J Bone Joint Surg Am. 1993;75(12):1795\u0026ndash;1803.\u003c/li\u003e\n\u003cli\u003eMatthews LS, Hirsch C. Temperatures measured in human cortical bone when drilling. J Bone Joint Surg Am. 1972;54(2):297\u0026ndash;308.\u003c/li\u003e\n\u003cli\u003eEriksson AR, Albrektsson T. Temperature threshold levels for heat-induced bone tissue injury. J Prosthet Dent. 1983;50(1):101\u0026ndash;107.\u003c/li\u003e\n\u003cli\u003eIrrgang JJ, Anderson AF, Boland AL, et al. Development and validation of the IKDC Subjective Knee Form. Am J Sports Med. 2001;29(5):600\u0026ndash;613.\u003c/li\u003e\n\u003cli\u003eDaniel DM, Stone ML, Sachs R, Malcom L. Instrumented measurement of anterior knee laxity in patients with acute ACL disruption. Am J Sports Med. 1985;13(6):401\u0026ndash;407.\u003c/li\u003e\n\u003cli\u003eWinter DA. Human balance and posture control during standing and walking. Gait Posture. 1995;3(4):193\u0026ndash;214.\u003c/li\u003e\n\u003cli\u003eAndriacchi TP, Dyrby CO. Interactions between kinematics and loading during walking for the normal and ACL-deficient knee. J Biomech. 2005;38(2):293\u0026ndash;298.\u003c/li\u003e\n\u003cli\u003eWoo SL, Hildebrand K, Watanabe N, Fenwick JA, Papageorgiou CD, Wang JHC. Tissue engineering of ligament and tendon healing. Clin Orthop Relat Res. 1999;367:S312\u0026ndash;S323.\u003c/li\u003e\n\u003cli\u003eWang IE, Mitroo DM, Chen FH, Lu HH. Biomimetic strategies for tendon/ligament-to-bone interface regeneration. J Biomed Mater Res A. 2012;100(10):2582\u0026ndash;2594.\u003c/li\u003e\n\u003cli\u003eCerulli G, Placella G, Sebastiani E, et al. Manual drilling preserves bone stock and enhances tendon\u0026ndash;bone healing: an in vivo rabbit study. J Orthop Res. 2024;42(1):88\u0026ndash;96.\u003c/li\u003e\n\u003cli\u003eFleming BC, Spindler KP. Biomechanics of ACL reconstruction. In: Miller MD, ed. Operative Techniques in Sports Medicine. 3rd ed. Elsevier; 2020:350\u0026ndash;359.\u003c/li\u003e\n\u003cli\u003eAmiel D, Woo SL, Harwood FL, Frank CB, Akeson WH. Biological response of ligaments to different immobilization conditions. J Orthop Res. 1983;1(3):170\u0026ndash;177.\u003c/li\u003e\n\u003cli\u003eKondo E, Yasuda K. Tendon graft healing to bone. In: Huard J, Fu FH, eds. Basic Science and Surgical Advances in Tendon Repair. Springer; 2019:223\u0026ndash;240.\u003c/li\u003e\n\u003cli\u003eZantop T, Petersen W. The role of biology in graft healing after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2014;22(11):2330\u0026ndash;2338.\u003c/li\u003e\n\u003cli\u003eMurray MM, Fleming BC, Badger GJ, et al. Bridge-enhanced ACL repair: Two-year results of a first-in-human study. Orthop J Sports Med. 2019;7(3):2325967118824356.\u003c/li\u003e\n\u003cli\u003eVaquero J, Vidal C, Cubillo A, et al. Biological augmentation in anterior cruciate ligament reconstruction: a review of current strategies. Arch Orthop Trauma Surg. 2020;140(12):1695\u0026ndash;1707.\u003c/li\u003e\n\u003cli\u003eLubowitz JH, Konicek J. All-inside ACL reconstruction. Arthrosc Tech. 2012;1(2):e145\u0026ndash;e150.\u003c/li\u003e\n\u003cli\u003eBedi A, Altchek DW. Anterior cruciate ligament reconstruction: surgical technique and biology. Arthroscopy. 2009;25(9):1015\u0026ndash;1026.\u003c/li\u003e\n\u003cli\u003eBarber FA, Aziz-Jacobo J. Biomechanical testing of new generation suture anchors. Arthroscopy. 2009;25(1):95\u0026ndash;99.\u003c/li\u003e\n\u003cli\u003eChang HC, Lu YT, Chen CH, et al. Tunnel enlargement and graft tension loss in ACL reconstruction: their relationship and the influence of different drilling techniques. Arthroscopy. 2013;29(5):775\u0026ndash;781.\u003c/li\u003e\n\u003cli\u003ePapalia R, Franceschi F, Vasta S, et al. Sparing the bone in ACL reconstruction: biological aspects of different drilling techniques. Musculoskelet Surg. 2015;99(2):87\u0026ndash;95.\u003c/li\u003e\n\u003cli\u003eGetgood A, Bryant D, Litchfield R, et al. Short-term outcomes after ACL reconstruction: a randomized clinical trial. J Bone Joint Surg Am. 2020;102(2):117\u0026ndash;125.\u003c/li\u003e\n\u003cli\u003eSmith PA, Thomas DM, Paci JM. Graft healing and tunnel biology in anterior cruciate ligament reconstruction. Sports Med Arthrosc Rev. 2019;27(3):100\u0026ndash;108.\u003c/li\u003e\n\u003cli\u003eRodeo SA. Biologic augmentation of tendon healing: role of platelet-rich plasma and other biologics. Sports Med Arthrosc Rev. 2020;28(3):84\u0026ndash;90.\u003c/li\u003e\n\u003cli\u003eKaeding CC, Pedroza AD, Reinke EK, et al. Risk factors for graft failure after ACL reconstruction in the MOON cohort. Am J Sports Med. 2015;43(7):1583\u0026ndash;1590.\u003c/li\u003e\n\u003cli\u003eFriel NA, Chu CR. The role of ACL injury in posttraumatic knee osteoarthritis. Clin Sports Med. 2013;32(1):1\u0026ndash;12.\u003c/li\u003e\n\u003cli\u003eClaes S, Verdonk P, Forsyth R, Bellemans J. The ligamentization process in ACL reconstruction: what happens to the graft? Knee Surg Sports Traumatol Arthrosc. 2011;19(8):1369\u0026ndash;1376.\u003c/li\u003e\n\u003cli\u003evan der List JP, DiFelice GS. Primary repair of the ACL: a paradigm shift. Orthop J Sports Med. 2017;5(3):2325967116686053.\u003c/li\u003e\n\u003cli\u003eSeil R, Becker R. Time for a paradigm change in meniscal repair: save the meniscus. Knee Surg Sports Traumatol Arthrosc. 2016;24(5):1421\u0026ndash;1423.\u003c/li\u003e\n\u003cli\u003eMayr R, Rosenberger R, Agraharam D, et al. Tunnel widening in ACL reconstruction: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2012;20(5):1063\u0026ndash;1070.\u003c/li\u003e\n\u003cli\u003eAhn JH, Lee SH. Biomechanical evaluation of bone tunnel healing after ACL reconstruction. Clin Orthop Surg. 2019;11(3):287\u0026ndash;293.\u003c/li\u003e\n\u003cli\u003eSalzler MJ, Richmond JC. ACL graft healing: biology and outcome factors. Sports Health. 2014;6(6):475\u0026ndash;480.\u003c/li\u003e\n\u003cli\u003eTohyama H, Yasuda K. Extracellular matrix of tendon and ligament. J Orthop Sci. 2000;5(3):248\u0026ndash;255.\u003c/li\u003e\n\u003cli\u003eWeiler A, Peters G, M\u0026auml;urer J, et al. Biomechanical properties and vascularity of ACL grafts can be predicted by MRI. Am J Sports Med. 2001;29(6):751\u0026ndash;756.\u003c/li\u003e\n\u003cli\u003eCarulli C, Matassi F, Soderi S, et al. Tunnel position and enlargement in ACL reconstruction: clinical and radiological outcomes. Musculoskelet Surg. 2017;101(1):37\u0026ndash;43.\u003c/li\u003e\n\u003cli\u003eMcCulloch PC, Lattermann C, Boland AL, et al. An illustrated history of ACL reconstruction. J Knee Surg. 2007;20(2):95\u0026ndash;104.\u003c/li\u003e\n\u003cli\u003eGianotti SM, Marshall SW, Hume PA, Bunt L. Incidence of ACL injury and risk factors: a review. Sports Med. 2009;39(8):679\u0026ndash;695.\u003c/li\u003e\n\u003cli\u003eMarx RG, Jones EC, Angel M, et al. Beliefs and attitudes of AAOS members regarding ACL injury treatment. Arthroscopy. 2003;19(7):762\u0026ndash;770.\u003c/li\u003e\n\u003cli\u003eDelince P, Ghafil D. ACL tears: conservative or surgical treatment? Knee Surg Sports Traumatol Arthrosc. 2012;20(8):1545\u0026ndash;1556.\u003c/li\u003e\n\u003cli\u003eArundale AJ, Bizzini M, Giordano A, et al. Rehabilitation and return to sport after ACL reconstruction: a systematic review. Br J Sports Med. 2018;52(22):1437\u0026ndash;1448.\u003c/li\u003e\n\u003cli\u003eWebster KE, Hewett TE. Meta-analysis of predictors of ACL graft rupture: younger age and return to sport. Br J Sports Med. 2019;53(15):943\u0026ndash;952.\u003c/li\u003e\n\u003cli\u003eSanders TL, Pareek A, Kremers HM, et al. Long-term follow-up of isolated ACL tears. Am J Sports Med. 2017;45(4):815\u0026ndash;820.\u003c/li\u003e\n\u003cli\u003eGrassi A, Zaffagnini S, Marcheggiani Muccioli GM, et al. Clinical outcomes and return to sport after ACL reconstruction in skeletally immature patients. Knee Surg Sports Traumatol Arthrosc. 2017;25(2):559\u0026ndash;566\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8278664/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8278664/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eAnterior 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.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eForty 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.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eManual 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\u0026thinsp;\u0026le;\u0026thinsp;2 mm difference, compared with 67% in the motorized group. Stabilometry showed an increase in ellipse area from 175 to 215 mm\u0026sup2; in the manual group and a decrease from 246 to 163 mm\u0026sup2; 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\u0026rarr;0.913) and increases in the motorized group (0.903\u0026rarr;0.938). None of these differences were statistically significant.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eManual 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.\u003c/p\u003e","manuscriptTitle":"Comparative Analysis of Clinical and Biomechanical Outcomes of Manual Versus Motorized Drilling Techniques in Bone Tunnel Preparation for Anterior Cruciate Ligament Reconstruction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-22 09:15:40","doi":"10.21203/rs.3.rs-8278664/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c628bffe-c4b2-44ae-959b-f0f3bd5d4e48","owner":[],"postedDate":"December 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-22T09:15:40+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-22 09:15:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8278664","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8278664","identity":"rs-8278664","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}