Vol 7 | Issue 2 | July-December 2021 | page: 9-12 | Rohan Bhargava, Parag Sancheti, Kailas Patil, Sunny Gugale, Sahil Sanghavi, Yogesh Sisodia, Obaid UI Nisar, Darshan Sonawane, Ashok Shyam

https://doi.org/10.13107/jmt.2021.v07.i02.164

Author: Rohan Bhargava [1], Parag Sancheti [1], Kailas Patil [1], Sunny Gugale [1], Sahil Sanghavi [1], Yogesh Sisodia [1], Obaid UI Nisar [1], Darshan Sonawane [1], Ashok Shyam [1]

[1] Sancheti Institute of Orthopaedics and Rehabilitation PG College, Sivaji Nagar, Pune, Maharashtra, India.

Address of Correspondence
Dr. Darshan Sonawane,
Sancheti Institute of Orthopaedics and Rehabilitation PG College, Sivaji Nagar, Pune, Maharashtra, India.
Email : researchsior@gmail.com.

Abstract

Background: Anterior cruciate ligament (ACL) rupture significantly reduces activity and quality of life in active individuals. This prospective study assesses whether tailoring hamstring graft diameter and restoring the patient’s native tibial insertion footprint during individualized anatomic single-bundle reconstruction improves early clinical outcomes.
Methods: Two hundred and one consecutive patients with symptomatic ACL tears underwent arthroscopic reconstruction with intraoperative measurement of native tibial footprint area and calculation of restored aperture using an ellipsoid formula. Graft diameters were recorded, and patients followed a standardised rehabilitation protocol. Outcomes included subjective IKDC and Lysholm scores and instrumented KT-1000 laxity at 6 and 12 months.
Results: Mean native tibial footprint area was 97.68 ± 18.86 mm2 and mean restored area was 76.1 ± 12.1 mm2, corresponding to a mean restoration of 79.25 ± 14.61%. The majority of patients received 9 mm grafts. Patients with >70% footprint restoration achieved superior IKDC and Lysholm scores at one year. Complication rates were low.
Conclusion: Individualized restoration of the tibial footprint with appropriately sized hamstring grafts correlates with favorable early outcomes after ACL reconstruction.
Keywords: ACL reconstruction, Tibial footprint, Graft size, IKDC, Lysholm.

Introduction:
Anterior cruciate ligament (ACL) rupture represents a common and functionally significant injury in young and active populations. Over the past century, treatment evolved from open repair and extra-articular tenodesis to arthroscopic intra-articular reconstructions as our understanding of ACL anatomy and biomechanics advanced. These historical and technical shifts are well documented and mark the progression toward less invasive and more anatomic procedures.[1–5] Contemporary practice has shifted the emphasis from simply re-establishing continuity to reproducing the native ACL insertion sites and restoring physiological knee kinematics[.6–10] The concept of anatomic reconstruction therefore focuses on placing tunnels and grafts to match individual patient morphology so as to reproduce native tensioning patterns of the anteromedial and posterolateral fibers and to restore rotational stability.[11–13] Individualized anatomic ACL reconstruction further adapts tunnel position and graft selection to the measured dimensions of the patient’s tibial and femoral footprints rather than applying a single standard technique to all knees.[7,8,11]Biomechanical and clinical studies have raised awareness that graft diameter and footprint coverage each affect knee stability and the risk of revision: smaller hamstring grafts appear linked to higher early revision rates while excessively large grafts risk impingement and damage to adjacent structures.[14–16] Given these considerations, precise intraoperative measurement and calculation of percentage footprint restoration have practical relevance for surgical planning. The present prospective cohort therefore investigates intraoperative footprint measurements, percentage of restored area, graft diameters commonly used, and their association with objective and patient-reported outcomes at one year after individualized single-bundle hamstring ACL reconstruction.[17]

Aims and objectives:
To determine (1) the native tibial ACL insertion site area using intraoperative measurements;
(2) the percentage of that footprint restored by the harvested hamstring graft and tunnel aperture;
(3) the association between percentage restoration, graft diameter, and early functional outcomes measured at 6 and 12 months.

Review of literature:
The evolution of ACL treatment reflects incremental improvements in understanding anatomy, graft biology and fixation.[1–5 ]The arthroscopic era allowed less invasive intra-articular reconstructions and a variety of autograft options emerged.[6–10] Comparative studies of single-bundle and double-bundle reconstructions have reported mixed results but have driven the field toward an anatomic philosophy that aims to reproduce native footprints and kinematics.[11–13] Investigators described practical methods to estimate insertion site area based on elliptical assumptions, establishing that individualized reconstructions commonly restore a substantial proportion of the tibial footprint.[17,18] Subsequent anatomical and cadaveric studies have highlighted population variability in tibial and femoral footprint dimensions, the ribbon-like morphology of the ACL midsubstance, and the need for classification of tibial insertion shapes to guide reconstruction.[12,19] Biomechanical studies and registry analyses reveal that graft diameter influences local knee mechanics and may affect clinical failure rates: smaller hamstring graft sizes have been associated with increased anterior translation and higher revision risk in younger patients, while larger grafts reduce meniscal stress and cartilage contact pressures.[14,15] Nevertheless, clinical outcomes depend on both accurate tunnel placement and sufficient graft size; increased graft diameter cannot fully compensate for malpositioned tunnels.[11,13 ]Recent work also emphasizes preoperative MRI as a useful adjunct to predict insertion dimensions and aid surgical planning.[17,20 ]Overall, the literature supports an individualized anatomic approach combining accurate footprint restoration and appropriate graft sizing to optimize early outcomes after ACL reconstruction.
Relevant anatomy: The knee’s osseous and soft tissue anatomy underlies ACL function and reconstructive strategy. The ACL is a flat, ribbon-like structure with two functional components that demonstrate differential tensioning through knee motion, with anteromedial fibers remaining taut during flexion and posterolateral fibers tightening near extension.[12,19] The primary blood supply derives from the middle geniculate artery with accessory supply from genicular branches; osseous attachments contribute little to intra-ligamentous vascularity.[12,19] Tibial and femoral insertion sites vary in size and shape across individuals and populations; these dimensions, measured as length and mid-width, allow estimation of insertion area by an ellipsoid formula.[17 ] Variation in tibial insertion shape has clinical relevance because different configurations may require modified tunnel trajectories or graft choices to avoid iatrogenic meniscal or root damage.[19]

Materials and methods:
This prospective single-center cohort included 201 patients admitted for primary arthroscopic hamstring ACL reconstruction. Inclusion required clinical and MRI confirmation of ACL rupture; patients with multiligament injuries, previous ipsilateral knee surgery, or contraindications to surgery were excluded. Preoperative workup included demographic data and anthropometric measurements. Semitendinosus harvest was performed, with gracilis added when additional graft bulk was required; grafts were quadrupled and sized. Intraoperative measurements of tibial insertion length and mid-width were taken using an arthroscopic ruler and used to calculate native insertion area by the ellipsoid formula ((length × mid-width) × π/4). Tunnel apertures were measured after reaming to compute restored graft aperture area; percentage restoration was calculated as (aperture area/native insertion area) × 100. Tibial and femoral tunnels were positioned to match the measured native insertion sites where permitted by anatomy and notch dimensions. Graft diameter was recorded (8, 9 or 10 mm most commonly). Postoperative rehabilitation followed a standardised protocol emphasizing early range of motion and graduated muscle strengthening. Outcomes were assessed by IKDC and Lysholm subjective scores and KT-1000 instrumented laxity testing at 6 and 12 months. Statistical analysis used ANOVA and unpaired t-tests to explore associations between graft size, percentage restoration and outcomes with p70% footprint restoration constituted 73.1% of the series. At 12 months, mean IKDC and Lysholm scores were higher in the >70% restoration group (IKDC mean ≈ 89.2; Lysholm mean ≈ 93.7) compared with the ≤70% group (IKDC mean ≈ 79.2; Lysholm ≈ 88.0). Objective KT-1000 measurements showed small, non-significant differences across graft sizes at 12 months. Overall complication rate was low (2.48%), including one deep infection, one DVT, two cases of impingement and one graft re-tear.

Discussion:
This series supports the concept that individualized anatomic ACL reconstruction — tailoring tunnel placement and graft selection to native footprint dimensions — can achieve high percentages of tibial footprint restoration and favorable early functional outcomes. Patients in whom >70% of the native tibial footprint was restored reported superior subjective scores at one year and most commonly received a 9 mm hamstring graft. These clinical observations are consistent with biomechanical data showing that larger grafts reduce anterior translation and articular contact stresses, and with registry studies linking small hamstring graft diameters to higher revision rates.[14,15] However, restoring footprint anatomy remains paramount; increasing graft size cannot fully compensate for non-anatomic tunnel placement.[11,13] The low complication and failure rates in this cohort suggest that individualized single-bundle reconstruction, when performed with careful intraoperative measurement and standardized rehabilitation, provides reliable short-term outcomes. Strengths of the series include prospective recruitment, consistent surgical technique and near-complete follow-up at one year; limitations are single-center design, surgeon-dependent intraoperative measurements and follow-up limited to the early postoperative period. Late outcomes such as osteoarthritis and medium- to long-term re-injury rates require longer observation. Future studies should examine whether the early benefits of footprint restoration translate into durable clinical advantages across broader populations and activity levels.[16–20]

Result
Two hundred and one patients completed one-year follow-up. The cohort was predominantly male (76%) with mean age 29.5 years; 90% were aged 21–40. Injury mechanisms were sports (43%), falls (36%) and road-traffic accidents (22%). Mean native tibial insertion area measured intraoperatively was 97.68 ± 18.86 mm². Mean restored graft aperture area after reaming was 76.1 ± 12.1 mm², yielding a mean percentage footprint restoration of 79.25 ± 14.61%. Seventy-three point one percent of patients achieved >70% footprint restoration. Graft diameters were most commonly 9 mm (62.7%), followed by 8 mm (26.4%) and 10 mm (10.9%). At 12 months, patients with >70% restoration demonstrated higher subjective scores (mean IKDC ≈ 89.2; mean Lysholm ≈ 93.7) compared with those with ≤70% restoration (mean IKDC ≈ 79.2; mean Lysholm ≈ 88.0). Instrumented KT-1000 laxity measurements showed only small, non-significant differences across graft sizes at one year. Overall complication rate was low (2.48%), comprising one deep surgical site infection, one deep vein thrombosis, two cases of graft impingement and one graft re-tear. Mean follow-up adherence was high and return-to-sport rates improved from preoperative baseline levels. No additional surgeries were performed during the follow-up other than the single documented graft re-tear revision within one year.

Conclusion:
In conclusion, individualized anatomic single-bundle hamstring ACL reconstruction that restores a substantial proportion of the native tibial footprint — most commonly achieved with a 9 mm graft in this cohort — is associated with improved early patient-reported outcomes and acceptable objective stability. Accurate intraoperative measurement and tailored graft selection appear to be practical strategies to optimize short-term results after ACL reconstruction. Longer-term studies are required to confirm durability and to evaluate implications for osteoarthritis and late re-injury.

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Institute Where Research was Conducted: Sancheti Institute of Orthopaedics and Rehabilitation PG College, Sivaji Nagar, Pune, Maharashtra, India.
University Affiliation: Maharashtra University of Health Sciences (MUHS), Nashik, Maharashtra, India.
Year of Acceptance of Thesis: 2020

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