Understanding Tunnel Malposition

https://pubmed.ncbi.nlm.nih.gov/8998862/

👥 Patient population

• 25 patients underwent revision ACL reconstruction after failure of a prior intra-articular ACL reconstruction
• Mean age at revision: 25 years
• Mean interval from primary to revision surgery: 30 months
• Mean follow-up after revision: 28 months.

📊 Etiology of primary graft failure

• After history, examination, radiographs, and review of prior operative records, the authors assigned a cause of failure for each case.
• The most common category was surgical technique
• Within this, tunnel placement accounted for 9 cases, making it the single most frequent technical error.

📍 Failure classification proposed by the Pittsburgh group

The paper’s classification of ACL graft failure included:

• Surgical technique
• Mechanical/biomechanical factors
• Failure of graft incorporation
• Trauma.

Within technical errors, the authors listed:

• Tunnel location
• Graft impingement
• Graft tension
• Graft fixation.

⚠️ Important nuance

• This paper does not report a specific percentage for femoral tunnel malposition alone
• It reports tunnel placement more broadly as the leading technical cause of failure.

🦴 Interpretation

• By 1996, the Pittsburgh group had already identified tunnel location as a central problem in failed ACL reconstruction
• This paper is therefore important as an early conceptual paper showing that technical tunnel errors were a major driver of graft failure.

💡 Key message

• Tunnel placement was the most frequent technical cause of failure in this revision ACL series, making this one of the early papers to highlight the tunnel-position problem in ACL reconstruction.

https://pubmed.ncbi.nlm.nih.gov/14967325/

👥 Patient population

• 20 patients undergoing revision ACL reconstruction
• All presented with persistent instability following primary ACL reconstruction
• Mid-term follow-up with clinical examination, KT-1000 testing, and functional assessment.

📊 Causes of primary ACL graft failure

• Technical errors were the most common cause of graft failure
• Femoral tunnel malposition identified as the leading technical error
• Other causes included:
• Tibial tunnel malposition
• Traumatic re-injury
• Graft stretching or rupture.

📍 Objective outcomes after revision surgery

• Residual anterior laxity remained common on KT-1000 testing
• However, many patients reported improved knee stability and function.

⚠️ Objective stability vs patient satisfaction

• Patient-reported outcomes were generally good despite measurable laxity
• Objective laxity did not correlate strongly with patient satisfaction.

🦴 Interpretation

• Malpositioned femoral tunnels can lead to persistent rotational instability and graft overload, resulting in graft failure.
• Accurate femoral positioning is therefore critical for successful ACL reconstruction.

💡 Key message

• Femoral tunnel malposition is a major technical cause of ACL reconstruction failure, emphasizing the importance of precise graft positioning in primary ACL surgery.

https://pubmed.ncbi.nlm.nih.gov/16458807/

👥 Patient population

• 31 patients underwent revision ACL reconstruction for recurrent instability
• 28 patients available for follow-up
• Mean follow-up: 4.2 years
• Mean age at revision surgery: 27 years.

📊 Tunnel malposition in failed ACL reconstructions

• 79% of failed ACL reconstructions showed radiographic FEMUR tunnel malposition
• Only 21% had anatomically positioned femoral and tibial tunnels on imaging (MRI/CT).

📍 Patterns of malposition

• Several cases showed excessively central femoral tunnel placement
• Malpositioned tunnels contributed to persistent instability and graft failure.

📈 Outcomes after revision surgery

• Revision ACL reconstruction corrected tunnel position
• Significant improvement in Lachman and pivot shift tests
• 97% of patients had ≤5 mm side-to-side difference on KT-1000 testing postoperatively.

🦴 Interpretation

• Incorrect tunnel placement is a major contributor to recurrent instability after ACL reconstruction.
• Revision surgery can improve stability when tunnel positioning is corrected.

💡 Key message

• Tunnel malposition was present in nearly 80% of failed ACL reconstructions, highlighting the importance of accurate graft positioning in primary ACL surgery.

https://pubmed.ncbi.nlm.nih.gov/20889962/

• 👥 460 patients enrolled across 87 surgeons (52 sites); median age 26 years, 57% male; 89% undergoing their first revision.
• ⚠️ Mode of failure:
• Traumatic: 32%
• Technical: 24%
• Biologic: 7%
• Combination of factors: 37% (most common overall category).
• 🎯 Technical failure details:
• Femoral tunnel malposition = 80% of technical failures (most common cause).
• Tibial tunnel malposition = 37%.
• 🦴 Graft choice in revision:
• 54% allograft
• 45% autograft
• Bone–patellar tendon–bone most common graft overall.
• 📉 Concomitant pathology common:
• 74% meniscal injury
• 73% chondral damage (Outerbridge ≥2)
• Only 10% had neither meniscal nor cartilage injury.

Key Insight

Revision ACL failure is rarely isolated — it is often multifactorial, with femoral tunnel malposition emerging as the dominant technical contributor.

https://pubmed.ncbi.nlm.nih.gov/20644911/

👥 Patient population

• Multicenter retrospective study across 10 French orthopaedic centers
• 293 patients undergoing revision ACL reconstruction
• Failures of primary ACL reconstruction analyzed over a 12-year period (1994–2005).

📊 Main causes of ACL reconstruction failure

• Femoral tunnel malposition: 36% (most common cause)
• Other causes included:
• Untreated laxity
• Tibial tunnel malposition
• Impingement
• Fixation failure
• New trauma
• Infection.

📍 Typical pattern of femoral tunnel malposition

• Failures were frequently associated with anterior placement of the femoral tunnel
• This produces a vertical graft orientation and inadequate rotational stability.

⚠️ Outcomes after revision surgery

• When failure was caused by anterior femoral tunnel malposition, revision surgery produced better outcomes:
• 44% IKDC A after revision
• compared with 24% IKDC A when failure was due to other causes.

🦴 Additional finding — meniscus preservation

• Total meniscectomy worsened outcomes after revision ACL reconstruction
• Patients with preserved menisci had better knee stability and function.

💡 Key message

• Anterior femoral tunnel malposition was the most common cause of ACL reconstruction failure (36%), highlighting the critical importance of accurate femoral tunnel placement.

https://pubmed.ncbi.nlm.nih.gov/23150344/

• 👥 Population:

Subset analysis of the MARS cohort (460 revision ACLRs).

Femoral tunnel malposition identified in 219 cases (47.6%), and as the sole cause in 117 patients (mean age 28.7 years).

• 📍 Most common technical error:

Femoral tunnel malposition was the leading technical cause of failure in revision ACLR.

• 📐 Type of malposition:
• Too vertical – 36%
• Too anterior – 30%
• Vertical + anterior – 27%

→ Vertical/anterior errors dominate.

• 🔧 Revision strategy:
• 82% required drilling an entirely new femoral tunnel
• Tibial tunnel could be reused in ~50%
• Both transtibial and AM portal techniques were used in revision
• 🦴 Graft choice highly variable:

No clear consensus—mix of autograft and allograft used in revision, reflecting surgeon preference rather than standardized algorithm.

Core Insight

In revision ACL surgery, femoral tunnel malposition—especially vertical/anterior placement—is the dominant preventable cause of failure, and most cases require creation of a new anatomic femoral tunnel.

https://pubmed.ncbi.nlm.nih.gov/28721590/

• 👥 110 revision ACL patients (mean age 28.7 yrs); failures classified as:
• Technical (non-traumatic): 64.5%
• Traumatic: 29.1%
• Biological: 6.4%
• 📍 Non-anatomic femoral tunnel = most common cause of technical failure (83.1%)

Tibial malposition also common (45.1%), but femoral malposition showed the strongest correlation with non-traumatic failure (p ≤ 0.05).

• 🔧 Technique matters:

Transtibial femoral drilling and femoral transfixation fixation were significantly associated with non-traumatic technical failure (p < 0.05).

• ⏱ Earlier failure in technical cases:

Non-traumatic failures occurred significantly earlier (mean 40 months) than traumatic failures (75 months).

• ⚠️ Important nuance:

High rates of non-anatomic tunnels were also seen in traumatic failures, suggesting tunnel error may predispose grafts to rupture under stress.

Core Message

Most revision ACL failures are technical rather than traumatic, and femoral tunnel malposition remains the dominant preventable factor.

https://pubmed.ncbi.nlm.nih.gov/33983487/

• 👥 117 patients total
• 58 successful primary ACLR
• 59 revision ACLR

Strict lateral radiographs used with Bernard quadrant method.

• 📍 Revision group had significantly more anterior femoral tunnels
• 38% ± 11% vs 28% ± 6% (p < 0.01)

Native center = 25% (PA dimension).

• 📐 Revision group also had more proximal (high) tunnels
• 30% ± 9% vs 38% ± 9% (p < 0.01)

Native center = 29% (PD dimension).

• ⚠️ Risk thresholds:
• ≥30% anterior → OR 6 for revision
• ≥40% anterior → OR 39
• PD ≤25% (high tunnel) → OR 13
• 🔄 Non-traumatic failures were the most anterior

Chronic failures averaged 41% PA vs 35% in traumatic failures.

Core Message

Anterior and proximal (high) femoral tunnel placement independently predicts revision ACL reconstruction — reinforcing that anatomic femoral positioning reduces revision risk.

https://pmc.ncbi.nlm.nih.gov/articles/PMC9165258/

👥 Patient population

• 78 patients from a prior randomized trial
• Mean follow-up 11.4 years
• All underwent primary transtibial ACL reconstruction.

📍 Main finding

• More anterior femoral tunnels were associated with higher long-term failure
• No-failure group: femoral tunnel at 37.7% posterior-to-anterior
• Failure group: 44.1% posterior-to-anterior.

⚠️ Safe zone identified

• A femoral tunnel placed within the most posterior 35% of the femoral condyle (parallel to Blumensaat) was associated with lower failure
• 15 of 16 failures (93.8%) were anterior to this cut-off.

📊 What tunnel position did not affect

• No significant relationship between femoral or tibial tunnel position and:
• IKDC subjective score
• Radiographic osteoarthritis.

🦴 Failure and OA rates

• 24.6% overall failure at 10 years
• 28.2% developed radiographic osteoarthritis.

✅ Key message

• Anterior femoral tunnel placement increases long-term ACL failure risk, while a more posterior femoral position is protective.

https://pubmed.ncbi.nlm.nih.gov/35219217/

👥 Patient population

• 244 patients undergoing primary ACL reconstruction
• Single surgeon, quadrupled semitendinosus autograft
• Compared two femoral tunnel positions using the anteromedial portal technique.

📍 Study groups

• Group A (117 patients): femoral tunnel at central ACL footprint
• Group B (127 patients): femoral tunnel placed closer to the AM bundle footprint.

⚠️ Failure rates differed significantly

• Central tunnel position: 10.3% failure (12/117)
• AM bundle position: 2.3% failure (3/127).

📊 Clinical outcomes

• AM bundle tunnel position showed:
• Higher Lysholm scores
• Better subjective IKDC scores
• Lower anterior knee laxity.

🦴 Knee stability findings

• Less anterior tibial translation in the AM bundle group
• Greater improvement in KT-1000 measurements compared with central tunnel placement.

💡 Key message

• Femoral tunnel position significantly affects ACL reconstruction outcomes, with central footprint tunnels showing up to 4× higher failure rates than tunnels placed closer to the AM bundle footprint.

https://pubmed.ncbi.nlm.nih.gov/37422027/

• 👥 104 patients (Level III study)
• 52 non-traumatic ACLR failures
• 52 matched controls (≥48-month follow-up)
• Mean age ≈ 32 years
• 📍 Femoral tunnel malposition matters
• Failed grafts had significantly more anterior & superior femoral tunnels
• DS ratio > 37.4% independently predicted failure (OR 1.09 per % increase)
• 📐 Lateral tibial slope (LTS) is the strongest predictor
• LTS > 6.7° → AUC 0.804
• OR 1.31 per degree increase
• 🦴 Narrow notch increases risk
• NWI < 26.4% independently associated with failure
• OR 0.81 (protective effect decreases as notch narrows)
• ⚠️ Multifactorial risk
• 73% of failed cases had ≥2 risk factors
• All patients with 3 risk factors failed
• Combination of anatomy + tunnel error dramatically increases risk

https://pmc.ncbi.nlm.nih.gov/articles/PMC11813002/

👥 Patient population

• 65 patients undergoing revision ACL reconstruction
• Mean age 30 years
• Retrospective analysis of failures between 2014–2022.

📊 Most common cause of failure

• Traumatic reinjury: 54.7% of failures
• 24 high-energy injuries (sports, collisions)
• 11 low-energy injuries (slips, falls).

📍 Technical failure: tunnel malposition

• Inappropriate tunnel placement: 18.8% of failures
• Femoral tunnel errors included anterior and posterior malposition, while some involved anterior tibial tunnel placement.

⚠️ Other causes of failure

• Graft failure: 12.5%
• Fixation problems: 6.3%
• Infection: 7.8%
• Multiple ligament injuries: 1.6%.

🦴 Associated intra-articular pathology

• Meniscal injuries present in 77% of revision cases.

💡 Key takeaway

• ACL reconstruction failure is multifactorial, but technical factors—particularly bone tunnel positioning—remain a critical determinant of surgical success.

https://pubmed.ncbi.nlm.nih.gov/16897068/

👥 Study population

• Cadaveric anatomical study analyzing the femoral insertion of the anterior cruciate ligament
• Detailed dissection performed to evaluate the anteromedial (AM) and posterolateral (PL) bundle insertions.

📊 Distinct bundle insertions

• The ACL femoral footprint consists of two distinct functional bundles:
• Anteromedial (AM) bundle
• Posterolateral (PL) bundle

These bundles have separate femoral attachment areas.

📍 Different functional roles

• AM bundle
• Tight in knee flexion
• Primarily controls anterior tibial translation
• PL bundle
• Tight in knee extension
• Contributes more to rotational stability

⚠️ Implications for ACL reconstruction

• A single round femoral tunnel cannot reproduce the distinct insertion areas of both bundles
• This anatomical complexity partly explains the interest in double-bundle reconstruction techniques.

🦴 Interpretation

• The femoral ACL insertion is not a single point but a complex anatomical region composed of functionally distinct bundle insertions.
• Simplified reconstruction techniques may therefore fail to replicate native ACL anatomy.

💡 Key message

• The ACL femoral footprint contains separate functional bundle insertions, highlighting the anatomical complexity that reconstruction techniques attempt to reproduce.

https://www.sciencedirect.com/science/article/abs/pii/S0749806311013429

👥 Study population

• Cadaveric knee specimens analyzed to evaluate arthroscopic landmarks used for femoral tunnel placement
• Aim: determine whether commonly used landmarks reliably identify the anatomic femoral ACL footprint.

📊 Key finding — variability of femoral anatomy

• Significant variability in femoral condyle size and morphology was observed across specimens
• This variability makes consistent identification of the ACL femoral footprint difficult using fixed arthroscopic landmarks.

📍 Limitations of arthroscopic visualization

• Arthroscopic viewing introduces parallax error, meaning the apparent location of structures changes depending on camera position
• Because of this optical effect, the anatomic center of the ACL footprint cannot be reliably quantified arthroscopically.

⚠️ Implications for femoral tunnel placement

• Surgeons relying on visual landmarks may misidentify the true femoral footprint
• This contributes to variability and potential malposition of femoral tunnels in ACL reconstruction.

🦴 Interpretation

• Femoral tunnel placement is technically challenging because:
• Arthroscopic visualization introduces parallax distortion
• Femoral anatomy varies significantly between patients.

💡 Key message

• Arthroscopic landmarks alone cannot reliably identify the anatomic femoral ACL footprint, contributing to variability in femoral tunnel placement.

https://pubmed.ncbi.nlm.nih.gov/20847222/

👥 Study population

• 137 knees analyzed

• Detailed measurements of femoral and tibial ACL insertion sites

• Aim: quantify size variability of the ACL footprints.

📊 Substantial variability in ACL insertion size

• Mean femoral ACL insertion length: ~16 mm

• Mean tibial ACL insertion length: ~18 mm

However, large variability was observed:

• Femoral insertion length ranged approximately 11–19 mm

• Tibial insertion length ranged approximately 9–24 mm

📍 Clinical relevance for ACL reconstruction

• In two-thirds of knees, the ACL insertion length was ≤16 mm

• Smaller insertion sites may not accommodate larger grafts or double-bundle reconstructions.

⚠️ Implications for surgical techniques

• A single standardized tunnel size or position may not reproduce native ACL anatomy in all patients

• Surgeons should measure the native footprint intraoperatively to guide reconstruction strategy.

🦴 Interpretation

• The ACL insertion sites demonstrate considerable inter-individual variability in size

• Reconstruction techniques should therefore be adapted to patient-specific anatomy.

💡 Key message

• ACL insertion site size varies substantially between individuals, meaning a standardized tunnel strategy may not reproduce native anatomy in all knees.

https://pubmed.ncbi.nlm.nih.gov/24972997/

👥 Study population

• 111 cadaveric knees analyzed to study native ACL femoral anatomy
• Detailed dissection of ACL insertion morphology.

📊 Key anatomical finding

• The ACL is not cylindrical or round
• The femoral attachment is a flat ribbon-like structure.

Typical dimensions reported:

• Width ≈ 16–18 mm
• Thickness ≈ 3–4 mm

This produces a flat, elongated insertion along the femoral wall.

📍 Implications for ACL reconstruction

• Conventional ACL reconstruction uses round reamers (7–10 mm)
• These create circular femoral tunnels.

However:

• A round tunnel cannot reproduce the flat ribbon-like femoral insertion of the native ACL.

⚠️ Geometric mismatch

This creates a fundamental mismatch:

Native ACL insertion

→ flat ribbon structure

Reconstruction tunnel

→ cylindrical bone tunnel.

Even if placed “anatomically”, the graft cannot replicate the native insertion geometry.

🦴 Interpretation

• ACL reconstruction techniques based on round tunnels inherently simplify native anatomy
• This may partly explain why reconstructed grafts often appear more cylindrical and vertical than the native ligament.

💡 Key message

• The native ACL femoral attachment is flat and ribbon-like, whereas ACL reconstruction relies on round tunnels, creating a fundamental mismatch between native anatomy and reconstruction geometry.

https://pubmed.ncbi.nlm.nih.gov/32613337/

• 👥 95 ACL-ruptured patients (mean age 26 yrs) underwent 3D MRI-based femoral footprint analysis.
• 📍 Marked intersubject variability

Femoral ACL center ranged:

1. 1.8–12.3 mm posterior
2. 7.7 mm distal to 4.8 mm proximal

(posterior condyle reference system).

• 📏 Distance from Over-the-Top (OTT) position:

Mean 1.9 ± 1.5 mm posterior and 13.8 ± 2.7 mm distal.

• ⚠️ Contemporary OTT femoral guides (4–10 mm offset) could restore the true femoral center in only 6.5% of patients.
• 🔧 Authors suggest AM-portal femoral guides with 10–18 mm proximal–distal offset may be required for true anatomic restoration.

Core Insight

The native femoral ACL center varies widely between patients — and standard over-the-top offset guides are insufficient to consistently reproduce it anatomically.

https://pubmed.ncbi.nlm.nih.gov/41426266/

👥 Study population

• 50 anatomical studies included
• 1652 knees analyzed in total

The meta-analysis compared ACL femoral and tibial footprint anatomy between the two populations.

📊 Femoral ACL footprint location

Location measured relative to the posterior edge of the lateral femoral condyle:

• Asian population: 35.2%
• Western population: 27.3%
• Statistically significant difference (P < 0.001)

Location relative to the Blumensaat line:

• Asian population: 39.4%
• Western population: 33%
• Statistically significant difference (P = 0.049)

➡️ This indicates the ACL femoral footprint lies more anterior and distal in Asian knees.

📐 Femoral footprint size

• Asian population:

96.3 mm² (95% CI 81.1–111.4)

• Western population:

126.8 mm² (95% CI 103.5–150)

• Significant difference (P = 0.03)

➡️ Asian knees have a smaller femoral ACL footprint.

📍 Tibial footprint

• No significant difference between Asian and Western populations for:
• Tibial footprint size
• Tibial footprint location

⚠️ Key implication

The femoral ACL footprint differs significantly between populations in both:

• Location
• Size

This demonstrates that the “anatomic footprint” is not universal.

🦴 Interpretation

If the ACL femoral footprint varies between populations, then:

• A single standardized femoral tunnel position may not reproduce native anatomy in every patient.

This variability partly explains why consistent anatomic femoral tunnel placement is challenging in clinical practice.

💡 Key message

• Meta-analysis of 50 studies (1652 knees) shows significant population differences in ACL femoral footprint size and location, highlighting the variability surgeons must contend with when drilling femoral tunnels.

https://pubmed.ncbi.nlm.nih.gov/32875301/

• 👥 12 sports fellowship–trained surgeons evaluated 10 patient-specific 3D printed femoral models derived from MRI.
• 📍 None could consistently identify the junction of the intercondylar and bifurcate ridges.

Mean ridge identification error:

1. 2.8–7.3 mm (proximal)
2. 2.4–8.0 mm (posterior) (p < .05).
• 🎯 None accurately identified the true femoral footprint center on bony models.

Mean tunnel error ranged:

1. 1.3–5.9 mm (proximal)
2. up to 4.3 mm posterior deviation (p < .05).
• 🔬 Intraoperative tunnels were more accurate than model-based placement.
• Surgical error: 3.7 ± 2.4 mm
• 3D model error: 5.8 ± 2.0 mm

(p = .0046).

• 🧠 Implication:

Osseous ridges alone are unreliable landmarks. Soft tissue cues and arthroscopic visualization significantly improve femoral tunnel localization.

Core Insight

Even experienced ACL surgeons cannot reliably identify femoral ridges on bone-only models — highlighting how dependent tunnel placement is on intraoperative soft-tissue landmarks.

https://pubmed.ncbi.nlm.nih.gov/28972789/

• 👥 41 patients underwent pre- and postoperative 3D MRI; 4 experienced sports surgeons using contemporary “anatomic” techniques (AM portal + transtibial).
• 📍 Mean femoral tunnel error distance:

3.6 ± 2.6 mm from the native footprint center (range 0–9.3 mm).

• 📉 29% of grafts had >50% of their footprint outside the native ACL footprint.
• 📐 Native footprint center (contralateral knee reference):

12.0 mm distal and 9.3 mm anterior to apex of deep cartilage.

Reconstructed tunnels were significantly different in both axes (P = .02, P = .01).

• 🔧 No difference between techniques or surgeons

Independent drilling vs transtibial → similar error (P = .07).

Error distribution similar across all 4 surgeons.

Core Message

Even with modern “anatomic” techniques and experienced surgeons, femoral tunnel placement frequently fails to reproduce the patient’s true native footprint, with clinically meaningful deviation.

https://pubmed.ncbi.nlm.nih.gov/34049511/

👥 Study population

• 20 patients with confirmed ACL rupture
• MRI scans evaluated by 8 observers:
• Orthopaedic surgeons
• Orthopaedic residents
• Musculoskeletal radiologists
• Observers identified the center of the femoral ACL footprint twice using MRI with 3D femur models.

📊 Intra-observer reliability (same observer repeating measurement)

• Mean 3D difference: 3.82 mm
• Indicates good repeatability when the same person performs the measurement.

📍 Inter-observer variability (between different observers)

• Mean 3D difference: 8.67 mm between observers
• Indicates substantial disagreement on where the femoral ACL footprint is located.

⚠️ Influence of observer experience

• Orthopaedic surgeons showed higher agreement than residents and radiologists
• Identifying the femoral footprint remains experience-dependent.

🦴 Interpretation

• Even with MRI and 3D modeling, there is considerable variability between observers in identifying the femoral ACL origin.
• Determining the correct femoral tunnel position therefore remains technically challenging and subjective.

💡 Key message

• Different observers identify the femoral ACL footprint up to ~9 mm apart on MRI, highlighting the variability and difficulty in defining the exact femoral tunnel position.

https://pubmed.ncbi.nlm.nih.gov/10524823/

👥 Study population

• 30 cadaver knees from 15 fresh male cadavers
• Compared 3 femoral tunnel drilling techniques:
• Double-incision (DI)
• Transtibial (TT)
• Anteromedial portal (AM).

📊 Study aim

• To test whether a correct deep femoral tunnel position could be achieved equally with the 3 techniques
• The reference point was placed just deep to the insertion of the anteromedial bundle of the ACL.

📍 Main radiographic findings

• Mean position of the superficial aspect of the intra-articular tunnel exit along Blumensaat’s line:
• DI: 36%
• TT: 36%
• AM: 34%
• No statistically significant difference between techniques
• None of the femoral holes was more anterior than 40%.

⚠️ Clinical background highlighted by the authors

• The paper cites prior clinical work showing that 88% of knees with correct deep femoral tunnel placement had satisfactory stability
• In contrast, superficial placement in the anterior 50% of the condylar width was associated with graft failure in 62.5% of knees.

🦴 Interpretation

• The key message of this paper is not that one technique was superior, but that all 3 techniques were capable of reaching a deep femoral position in the cadaver model
• The authors conclude that technique choice should depend on surgeon preference and clinical results.

💡 Key message

• Deep femoral tunnel placement could be achieved with DI, TT, and AM techniques in a cadaver model, reinforcing the importance of femoral tunnel position rather than simply the drilling approach.

https://pubmed.ncbi.nlm.nih.gov/23276417/

👥 Patient population

• 8,375 primary ACL reconstructions from the Danish Knee Ligament Reconstruction Register
• Compared anteromedial (AM) portal drilling vs transtibial (TT) drilling for femoral tunnel placement.

📊 Revision risk

• AM technique: 5.16% revision at 4 years
• TT technique: 3.20% revision at 4 years.

📈 Relative risk of revision

• AM drilling doubled the risk of revision ACL surgery
• Adjusted RR = 2.04 compared with transtibial drilling.

⚠️ Objective instability findings

• AM technique associated with:
• Higher pivot shift risk (RR 2.86)
• Higher sagittal instability >2 mm (RR 3.70).

📊 Patient-reported outcomes

• KOOS and Tegner scores were similar between techniques despite differences in revision risk.

💡 Key message

• Femoral drilling technique significantly affects revision risk, with anteromedial portal drilling showing higher revision rates than transtibial techniques in registry data.

https://pubmed.ncbi.nlm.nih.gov/28721590/

👥 Patient population

• 101 patients undergoing revision ACL reconstruction
• Prior primary ACL reconstructions performed using:
• Transtibial (TT): 64 cases
• Anteromedial (AM): 37 cases.

📊 Non-anatomic tunnel positioning

• 77.2% had non-anatomic femoral tunnel positions
• 40.1% had non-anatomic tibial tunnel positions on CT analysis.

📍 Comparison between drilling techniques

• TT technique:
• Non-anatomic femoral tunnels 79.7%
• AM technique:
• Non-anatomic femoral tunnels 73%.

⚠️ No significant difference between techniques

• Rates of malposition were similar between TT and AM techniques (p > 0.05).

🦴 Interpretation

• Even with techniques designed to improve anatomical placement (AM drilling), accurate femoral tunnel positioning remains difficult in clinical practice.

💡 Key message

• Most failed ACL reconstructions show non-anatomic tunnel placement, and changing drilling technique alone does not reliably prevent femoral tunnel malposition.

https://pubmed.ncbi.nlm.nih.gov/36435433/

• 🏷️ Stop using the word “anatomic.”

A single cylindrical graft cannot recreate a ribbon-like ACL that is ~3.5× wider at its insertions than its midsubstance. The term is vague, misleading, and implies superiority without precision.

• 📍 Femoral tunnel: restore the direct fibers.

The direct fibers (just posterior to the lateral intercondylar ridge) bear 85–95% of load and are most critical for resisting anterior translation and pivot shift.

• 🦴 Tibial tunnel precision matters.

The native ACL tibial insertion is C-shaped and large; any tunnel within it could be labeled “anatomic.” Authors prefer placement in the central footprint without impingement, with clear description of exact position.

• 🔄 Address associated lesions.

Rotational control often depends on the IT band / anterolateral complex, not just ACL graft position. High-grade pivot shift may require lateral extra-articular tenodesis.

• 🔬 Future direction:

Techniques should be described with precise anatomical tunnel coordinates, not marketing terminology — and validated with patient outcomes and return-to-play data.

Core Message

Don’t call it “anatomic.”

Describe it precisely. Restore the load-bearing fibers. Validate it clinically.

https://pmc.ncbi.nlm.nih.gov/articles/PMC12575944/

• 🎯 Core Argument:

Many procedures labeled “anatomic” are actually pseudo-anatomic and may not be biomechanically superior. The term can be misleading and used as a proxy for “better.”

• 🦴 ACL Example:

Moving the femoral tunnel from the traditional AM bundle position to the so-called “central footprint anatomic” position increased graft rerupture rates in professional soccer players (up to 18.5% with hamstrings). The author reverted to AM placement.

• 🔄 LET Example:

Lateral extra-articular tenodesis (LET) is clearly not anatomic, yet significantly reduces ACL graft rerupture (as low as 2% in elite athletes when combined with patellar tendon graft + AM position).

• ⚖️ PLC & MCL Reconstructions:

Several “anatomic” techniques fail to reproduce true dynamic biomechanics and may not restore rotational stability as effectively as simpler, biomechanically optimized constructs.

• 🔬 Philosophical Shift:

Authors advocate for:

1️⃣ Biomechanical validation over cosmetic anatomy

2️⃣ Abandoning the misleading “anatomic” label

3️⃣ Laboratory testing + clinical outcomes as the gold standard

Core Message

Biomechanical function—not visual resemblance to native anatomy—should define successful ligament reconstruction.

https://www.sciencedirect.com/science/article/abs/pii/S074980632300587X

• 👥 Paper type: Editorial commentary reviewing evidence on non-traumatic ACL graft failure and femoral tunnel malposition (Arthroscopy 2024, Lucidi et al.)
• 🎯 Main message: The number one cause of ACL reconstruction failure is a misplaced femoral tunnel, typically too anterior or too vertical (Arthroscopy 2024, Lucidi et al.)
• 📊 Technical error prevalence: In revision cohorts, technical errors account for ~60% of failures, and femoral tunnel malposition is implicated in up to 80% (Arthroscopy 2024, Lucidi et al.)
• ⚠️ Consequences of malposition:
• Increased anterior translation
• Residual pivot shift
• Higher postoperative meniscal tears
• Increased revision rates (Arthroscopy 2024, Lucidi et al.)
• 🔁 Proposed solution:

The Over-The-Top technique + lateral extra-articular tenodesis (LET) avoids femoral tunnel malposition and improves rotatory control, particularly in patients with narrow notch or high tibial slope (Arthroscopy 2024, Lucidi et al.)

• 🛠 Revision advantage:

If failure occurs, there is no femoral tunnel widening, osteolysis, or hardware conflict, simplifying revision surgery (Arthroscopy 2024, Lucidi et al.)