Next Article in Journal
Attitudes Toward Perioperative Antibiotic Prophylaxis in Primary Hip and Knee Arthroplasty and Hip Hemiarthroplasty: A Survey of Egyptian Joint Replacement Surgeons—Is It Time for Developing National Guidelines?
Previous Article in Journal
Artificial Intelligence-Based Prediction of Surgeon Stress in Robot-Assisted Minimally Invasive Surgery Using ECG Sensor Data
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Surgeries
Volume 7
Issue 2
10.3390/surgeries7020068
surgeries-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Effect of Sagittal TTTG on Graft Failure After Anterior Cruciate Ligament Reconstruction

by
Sebastian Schmidt
1,2,*,
Chilan B. G. Leite
1,
Domenico Franco
1,3,
Ali Darwich
2,
Cale A. Jacobs
1 and
Christian Lattermann
1
1
Department of Orthopedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
2
Department of Orthopaedic and Trauma Surgery, University Medical Centre Mannheim, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
3
Operative Research Unit of Orthopaedic and Trauma Surgery, Fondazione Policlinico Universitario Campus Bio-Medico, 00128 Rome, Italy
*
Author to whom correspondence should be addressed.
Surgeries 2026, 7(2), 68; https://doi.org/10.3390/surgeries7020068
Submission received: 24 February 2026 / Revised: 28 April 2026 / Accepted: 20 May 2026 / Published: 9 June 2026
(This article belongs to the Section Minimally Invasive and Robotic Surgery Group)
Browse Figures
Versions Notes

Abstract

Background: Anterior cruciate ligament reconstruction (ACLR) is a common orthopedic procedure with generally favorable outcomes, yet graft failure remains a significant challenge, particularly in young and active patients. While various anatomical and biomechanical risk factors for graft failure have been proposed, the influence of the sagittal tibial tubercle–trochlear groove (sTTTG) distance, representing anterior–posterior alignment of the tibial tubercle, has not been sufficiently explored. This study aimed to evaluate the association between sTTTG and ACL graft failure and assess contributing biomechanical variables, including tibiofemoral rotation (TFR), posterior tibial slope (PTS), and knee flexion angle. Methods: For this secondary analysis, a retrospective matched case–control study was conducted, involving 151 patients with ACL graft failure who underwent revision ACLR and 151 controls with intact grafts after a minimum 2-year follow-up period. sTTTG was measured on axial MRI as the anteroposterior distance from the trochlear groove to the tibial tubercle, perpendicular to the posterior femoral condylar axis. Secondary measurements included TT-TG, TFR, medial and lateral PTS, and knee flexion angle. Group differences as well as factors predictive of sTTTG were analyzed. Results: The ACLR failure group demonstrated a significantly lower sTTTG distance compared to controls (0.5 ± 4.6 mm vs. 2.4 ± 4.8 mm, p = 0.001). Logistic regression analysis revealed that a 1 mm increase in sTTTG was associated with an 8% reduction in revision risk (OR = 0.93 per 1 mm increase; 95% CI, 0.88–0.97; p = 0.003), although the predictive accuracy was low (AUC = 0.6). Multivariable analysis identified lateral PTS and knee flexion as significant independent predictors of sTTTG. Conclusions: A decreased sTTTG distance was significantly associated with ACL graft failure, underscoring the relevance of sagittal tibial tubercle positioning in ACL biomechanics. While not an independent clinical decision-making tool, sTTTG appears relevant to graft failure and may be considered in future risk assessment strategies.

1. Introduction

Anterior cruciate ligament reconstruction (ACLR) is a widely performed orthopedic procedure, yielding favorable outcomes for many patients [1,2]. Nonetheless, graft failure remains a significant concern, particularly among active individuals, with reported failure rates ranging from 5% to 10% [2,3,4]. While various anatomical and biomechanical factors, such as posterior tibial slope, tunnel placement, and graft type, have been associated with ACLR failure, the role of axial alignment, particularly the sagittal positioning of the tibial tubercle, has garnered increasing attention [4,5,6,7].
Traditionally, the tibial tubercle–trochlear groove (TT-TG) distance, measured in the axial plane, has been utilized to assess lateralization of the tibial tubercle, especially in the context of patellofemoral instability (PI) [8,9,10]. More recently, the sagittal TT–TG (sTTTG) distance has been introduced to describe the anteroposterior position of the tibial tubercle relative to the trochlear groove, providing a potential surrogate for sagittal alignment of the extensor mechanism [11,12,13]. Current knowledge regarding sTTTG is primarily derived from studies on patellofemoral instability, where altered sagittal alignment has been associated with cartilage damage and abnormal joint loading [11].
While these findings provide a useful biomechanical framework, their direct applicability to ACL biomechanics remains uncertain. Specifically, it has been hypothesized that a more anterior tibial tubercle may increase anterior tibial shear forces and thereby elevate stress on the ACL graft [14]. Despite this plausible association, the influence of sTTTG on ACL graft survival remains underexplored.
Furthermore, dynamic joint behaviors, such as tibiofemoral rotation (TFR), have been implicated in ACL injuries and failures [15,16]. Increased internal tibial rotation has been associated with higher-grade pivot-shift phenomena and injuries to the anterolateral ligament (ALL), underscoring the complex interplay between rotational control and ligamentous integrity [15,16]. However, the extent to which rotational malalignment affects static measures like the sTTTG, and whether this interaction predisposes patients to graft failure, remains unclear.
Therefore, the primary aim of this study was to evaluate the association between the sTTTG distance and ACL graft failure, hypothesizing that a more anterior tibial tubercle (i.e., lower sTTTG) correlates with an increased risk of revision surgery. A secondary objective was to assess the influence of knee flexion, tibiofemoral rotation, and posterior tibial slope on the sTTTG measurement, thereby elucidating its dynamic nature and contextual relevance in ACL biomechanics.

2. Methods

This secondary analysis of a previously published study was conducted with approval from our institutional review board [16].

2.1. Patient Selection

Medical records from our institutional database were reviewed for patients who had undergone either revision ACLR due to graft failure (ACLR failure group) or primary ACLR with an intact graft after a minimum follow-up of 2 years (intact ACLR group). From the original dataset, the full cohort was used for the analysis of demographic variables as well as tibiofemoral rotation (TFR), posterior tibial slope (PTS), and TT–TG distance. Primary ACLR for all patients in the intact ACLR group was performed by one of two senior surgeons. For the ACLR failure group, primary ACLR was conducted by one of these surgeons, or patients were referred for revision after having primary ACLR performed at an external facility. All patients who had revision ACLR performed by either senior surgeon between December 2006 and May 2021 were included. ACLR was indicated in all patients based on clinical signs of knee instability. Although minor technical refinements occurred over the study period, all procedures were consistently performed using an anteromedial portal technique with anatomical placement of the femoral tunnel. Graft selection was made on an individual basis through shared decision-making between the surgeon and the patient, with allografts preferentially used in older patients.
Surgery was performed once the acute inflammatory phase had resolved, defined by minimal joint effusion and restoration of at least 120° of knee flexion. Postoperative management followed standardized rehabilitation protocols, including structured physical therapy. Weight-bearing and range of motion were temporarily restricted depending on concomitant procedures, particularly in cases involving cartilage repair or meniscal treatment. Graft failure was defined as anterior knee instability in symptomatic patients, confirmed by clinical examination, with an ACL graft tear also identified on magnetic resonance imaging (MRI) and verified during arthroscopic surgery. Patients were excluded if they had: (1) combined ligamentous injuries requiring additional ligament reconstruction (e.g., posterior cruciate ligament, lateral collateral ligament, medial collateral ligament, or posterolateral corner), (2) coronal malalignment of the lower limb (e.g., varus or valgus deformity > 3° on long-leg standing radiographs) necessitating corrective osteotomy, (3) advanced knee osteoarthritis (Kellgren–Lawrence grade 3 or 4), or (4) incomplete data at 2 years, including unavailable preoperative imaging. Grade 1 or 2 medial collateral ligament injuries and meniscal injuries requiring partial meniscectomy, meniscal repair, or cartilage repair procedures were not considered exclusionary. A total of 151 patients meeting these criteria were included in the ACLR failure group. A control group of patients who had undergone primary ACLR with no evidence of failure at final follow-up was created. Knee instability was ruled out in these asymptomatic patients through clinical examination, with a minimum follow-up of 2 years, and surgery was performed between December 2006 and September 2019. Patients were matched 1:1 based on sex, age (≤20, 21–30, 31–40, and >40 years), and the presence of concomitant meniscal injury at the time of primary ACLR.
A subgroup analysis evaluated injuries of the anterolateral ligament (ALL). All patients from the intact ACLR group who were skeletally mature and had MRI scans capable of detecting the ALL were included.
Demographic parameters, including age, body mass index (BMI), affected side, as well as injury and surgical details (e.g., time to failure for the ACLR failure group, follow-up duration for the intact ACLR group, and graft type), were recorded for all patients. Baseline patient characteristics of the previously established cohort at the time of primary ACL reconstruction have been reported [16]. Briefly, the study cohort comprised 302 patients with a mean age of 25.8 ± 10.2 years and a mean follow-up duration of 4.8 ± 3.6 years, consisting of 174 males (57.6%) and 128 females (42.4%). No group differences were noted in sex (p > 0.99), mean BMI (p = 0.211), concomitant meniscal injuries (p > 0.99), or allograft utilization (p = 0.25; Table 1).
Additionally, for the subgroup analysis, the presence and grading of pivot-shift were recorded. Pivot-shift was assessed under anesthesia by senior surgeons using the International Knee Documentation Committee’s 4-point scale: normal/negative (0), glide (1), clunk (2), and gross (3) [17].

2.2. Imaging Evaluation and Measurements

For patients with multiple MRI scans, the preoperative MRI examination conducted closest to the time of their ACLR was selected for analysis. The MRI scans, comprising 1.5 T and 3.0 T images with the knee in extension, were evaluated. All measurements were executed using standardized angle and distance measurement tools within the institution’s picture archiving and communication system. As this study represents a secondary analysis, measurement reliability demonstrated good to excellent reproducibility with interobserver ICCs ranging from 0.88 to 0.94 and intraobserver ICCs from 0.88 to 0.96 [15,16].

2.3. Sagittal TT-TG Distance

The sTTTG distance was measured on axial T2-weighted MRI (Figure 1). The measurement was defined as the anteroposterior distance between the deepest point of the trochlear cartilage and the most anterior point of the tibial tubercle at the patellar tendon insertion, referenced perpendicular to the posterior femoral condylar axis [13,18,19]. Positive values indicated that the tibial tubercle was located posterior to the trochlear groove.

2.4. Knee Flexion Assessment

As an additional measurement, the knee flexion angle of the MRI was measured on the mid-sagittal image as the angle subtended by the long axes of the femur and tibia (Figure 2).

2.5. Tibiofemoral Rotation Angle

The tibiofemoral rotation angle (TFR) between the distal femur and proximal tibia at the knee joint level, consistent with prior descriptions, was assessed on axial MRI [16]. TFR was defined as the angle between the posterior femoral condylar axis at the level of the trochlea’s deepest point and the posterior tibial condylar axis just distal to the tibial plateau articular surface. A positive angle indicates a tibial internal rotation. In the prior study, knee rotation angle was significantly larger for those with ACL failure versus those with an intact ACL (5.8° ± 4.6° vs. 3.0° ± 3.4°, p < 0.001) [16].

2.6. Posterior Tibial Slope

The posterior tibial slope (PTS) was measured using established methods [16,20]. On mid-sagittal MRI, the tibial longitudinal axis was defined by two circles: a proximal circle fit to the articular cortices and a distal circle fit to the metaphyseal cortices, with its center constrained to the proximal circle’s circumference. The axis was drawn through the centers of both circles. For medial and lateral PTS, the angle was measured between a line perpendicular to the tibial axis and a tangent line along each plateau’s articular surface on their respective mid-sagittal slices. In the previous study, the medial posterior tibial slope (PTS) measured 4.3° ± 2.8° in the ACL failure group and 4.6° ± 3.0° in the ACL-intact group. The lateral PTS was 4.7° ± 3.1° in the failure group and 4.2° ± 3.0° in the intact group. None of these differences reached statistical significance (p = 0.376 and 0.146, respectively) [16].

2.7. TT-TG Distance

The tibial tubercle–trochlear groove (TT-TG) distance was assessed on axial MRI sequences according to established measurement protocols [21]. After identifying the deepest point of the trochlear groove and drawing a reference line perpendicular to the posterior femoral condylar tangent line, a parallel line through the central axis of the tibial tuberosity at the patellar tendon insertion site was constructed. The TT-TG distance was then calculated as the linear distance between these two parallel reference lines, representing the degree of lateralization of the tibial tubercle relative to the trochlear groove. In the previous study, the tibial tubercle–trochlear groove (TT-TG) distance measured 12.5 ± 4.4 mm in the ACL failure group and 13.2 ± 3.7 mm in the intact ACL reconstruction group, with no statistically significant difference (p = 0.065) [16].

2.8. ALL Assessment

The ALL was identified using standardized MRI criteria [15,22]. On coronal T2 images, the ligament consistently appeared as a well-defined hypointense band originating from the posterosuperior aspect of the lateral femoral epicondyle and coursing distally to insert on the tibial plateau between Gerdy’s tubercle anteriorly and the fibular head posteriorly. Following a comprehensive evaluation, each ALL was systematically analyzed in three anatomical segments: femoral, meniscal, and tibial portions. Ligaments were classified as intact when demonstrating continuous fibers with homogeneous low signal intensity throughout all segments, while injuries were characterized by the presence of fiber discontinuity, abnormal contour irregularity, focal signal hyperintensity or the presence of a Segond fracture [15,22].
The following measures were collected as part of the prior study [16], and the methods are summarized below.

2.9. Statistical Analysis

Descriptive statistics are reported as the mean ± standard deviation (SD) for continuous variables and as numbers and percentages for categorical variables. Data distribution and normality were evaluated by histogram analysis and the Shapiro–Wilk test. A comparison between descriptive statistics was performed using the independent-samples t test or Mann–Whitney U test, when appropriate, for continuous variables, and using the Fisher exact test for categorical variables. A multivariable linear regression model was used to identify factors influencing sTTTG distance and previously reported TFR and TT-TG, as well as medial and lateral posterior tibial slope measurements [16]. Given the significant impact of knee flexion angle on sTTTG, this influence was removed through linear regression, and the residualized sTTTG values were used in subsequent predictive analyses. A univariable logistic regression model was then applied to assess the association between flexion-adjusted sTTTG and the risk of revision surgery. In addition, the discriminative capacity of sTTTG was evaluated using receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC).
All analyses were performed using R 4.4.2. (R Foundation for Statistical Computing, Vienna, Austria). Statistical significance was set as p < 0.05. Post hoc power analysis revealed that a sample size of 151 patients per group provided a power of 0.93 (effect size d = 0.40; α = 0.05) to detect differences in the sTTTG between the intact ACLR and failed ACLR groups.

3. Results

Significant differences were observed for sTTTG distance between the ACLR failure group (0.5 ± 4.6 mm) and the intact ACLR group (2.4 ± 4.8 mm, p < 0.001) and knee flexion on MRI (6.6° ± 5.4° vs. 8.0° ± 5.2°, p = 0.022). Additionally, the influence of graft choice on the sTTTG was examined. There was no significant difference between BPTB (bone–patellar tendon–bone) autograft (1.95 ± 4.98 mm) and hamstring autograft (1.45 ± 4.46 mm; p = 0.502).
The multivariable linear regression model identified several factors significantly associated with sTTTG (Table 2). Increased knee flexion on MRI (β = 0.17, p < 0.001) was associated with higher sTTTG values, while a steeper lateral posterior tibial slope (β = −0.37, p = 0.022) was associated with lower sTTTG values. TFR, TT-TG, and medial PTS did not show significance. The overall explanatory power of the model was modest, with an R2 of 0.11.
In univariable logistic regression, the sagittal tibial tubercle–trochlear groove (sTTTG) distance, adjusted for knee flexion angle through linear regression, was significantly associated with revision risk (OR = 0.93 per 1 mm increase; 95% CI, 0.88–0.97; p = 0.003), indicating a protective effect of higher sTTTG values. Despite this statistical significance, the discriminative ability of flexion-adjusted sTTTG to differentiate between revision and non-revision cases remained limited, with an AUC of 0.60.
For the subgroup analysis on the ALL assessment, 115 patients from the intact ACLR group were identified. Among them, 16 patients had an intact ALL, while 99 showed ALL injury. Of these patients, 87 had signal abnormalities without discontinuity, and 12 had complete discontinuity. No significant differences in pivot-shift grade were observed between the groups. Similarly, differences in the sTTTG distance (p = 0.218) and knee flexion angle (p = 0.802) on MRI were not statistically significant (Table 3). In addition, there was no significant correlation between pivot-shift grade and sTTTG (p = 0.591) or knee flexion angle on MRI (p = 0.32). Only the differences in TFR reached statistical significance (injured ALL: 4.8 ± 3.4°; intact ALL: 2.1 ± 2.7°, p = 0.003).

4. Discussion

The most important finding of this study is that a lower sTTTG distance is associated with an increased risk of graft failure following ACLR, suggesting that a more posterior position of the tibial tubercle relative to the trochlear groove may be protective against graft failure. This finding highlights the potential role of sagittal plane malalignment in contributing to biomechanical stress on the ACL graft. While this association was statistically significant, the discriminative ability of sTTTG was limited (AUC ~0.60), indicating that it should not be considered a standalone predictive parameter. Instead, sTTTG appears to represent one component within a multifactorial biomechanical framework. In this context, its relevance lies in combination with other factors, particularly sagittal alignment parameters such as posterior tibial slope, TFR, and ALL integrity [15,16,23,24].
The study further identified concomitant factors that interact with sTTTG to influence graft survival. Increased tibiofemoral internal rotation (5.8° vs. 3.0°, p < 0.001), reduced knee flexion on MRI (6.6° vs. 8.0°, p = 0.022), and a steeper lateral posterior tibial slope (9.5° vs. 8.8°, p = 0.026) were significantly associated with the failure group. These findings suggest a complex interplay between static alignment and dynamic joint kinematics. For instance, excessive internal rotation may exacerbate rotational instability, compounding the anterior shear stress imposed by a low sTTTG. Similarly, a steeper lateral tibial slope, known to increase anterior tibial translation, likely synergizes with anterior tubercle positioning to create a “perfect storm” of biomechanical risk [25,26]. Multivariable regression reinforced these relationships, demonstrating that lateral slope independently influenced sTTTG values. There is currently disagreement in the literature regarding the influence of knee flexion on the measurement of sTTTG [1,13]. This study demonstrated a clear relationship between knee flexion on MRI and the sTTTG value. Furthermore, this study showed no significant influence between TFR and sTTTG, although it could be assumed that increased tibial internal rotation increases the sTTTG, as the tibial tubercle moves posterior in relation to the trochlear groove. Similarly, an injury to the ALL did not lead to this effect.
The univariable logistic regression revealed that each 1 mm increase in sTTTG reduced revision risk by 8%, confirming its protective effect. Yet, the poor discriminative ability of sTTTG alone underscores its limitations as an isolated predictor. This aligns with the multifactorial nature of ACL failure, where no single parameter fully captures risk. For example, while sTTTG reflects static sagittal alignment, dynamic factors like TFR or anterolateral ligament (ALL) integrity, which showed no significant correlation with sTTTG in subgroup analysis, may independently contribute. The lack of association between sTTTG and pivot-shift grade (p = 0.591) or ALL injury (p = 0.218) suggests that rotational instability and lateral compartment pathology operate through distinct pathways. Notably, the subgroup analysis revealed higher internal tibiofemoral rotation (TFR) in patients with ALL injuries (4.8° vs. 2.1°, p = 0.003), emphasizing rotational malalignment’s role in lateral structural compromise [16]. These findings collectively argue for a holistic evaluation of alignment, rotation, and soft tissue integrity when assessing graft failure risk.
Traditional parameters for assessing patellofemoral instability have been repeatedly investigated to determine their influence on ACL graft failure [10,27,28]. For the TT-TG in particular, some studies have shown that an increased TT-TG distance predicts increased rotational laxity after an ACL injury, especially in a concomitant ALL injury [27,29]. The current findings extend this concept to sTTTG and ACL graft failure, bridging patellofemoral and tibiofemoral biomechanics. Although studies have shown that a posteriorly positioned tibial tubercle (reflected by higher sTTTG values) correlates with increased patellofemoral contact pressures and symptomatic cartilage lesions [12,13,19,30], in the context of ACL graft failure, the same posterior tibial tubercle positioning appears protective. This divergence underscores the biomechanical duality of sTTTG: while posterior alignment may overload the patellofemoral compartment, it stabilizes the tibiofemoral joint by mitigating graft strain.
The protective effect of increased sTT-TG in ACL grafts likely stems from reduced anterior translation during dynamic movements, which is also associated with a lower internal TFR. This stands in contrast to the increased patellofemoral pressure that predisposes its cartilage to degeneration [29].
Clinically, these findings suggest that sTTTG may be considered as part of a comprehensive preoperative assessment in ACL-injured patients, particularly in the presence of additional risk factors such as an increased posterior tibial slope. However, given the multifactorial nature of graft failure and the limited predictive performance observed, sTTTG should not be used in isolation to guide surgical decision-making. To mitigate biomechanical stressors, additional surgical procedures, such as tibial tubercle osteotomy or slope correction, may be considered; however, supporting biomechanical evidence is currently limited, and further research is required before clinical recommendations can be made. Rehabilitation protocols emphasizing neuromuscular control to counteract anterior shear and rotational forces could further reduce the risk of ACL injury.
Future research should prioritize prospective cohorts to validate the associations found in this study. Dynamic imaging modalities, such as weight-bearing MRI or 4D CT, could clarify how sTTTG interacts with functional kinematics.

5. Limitations

This study has several limitations. Although its retrospective design may introduce selection bias, strict inclusion criteria and 1:1 matching based on age, sex, and meniscal status helped reduce confounding. Variability in surgical techniques could also affect outcomes; however, the fact that only two experienced surgeons performed all primary ACLRs in the control and in the failure group minimizes procedural heterogeneity. Although graft choice was recorded and the two most common autografts (BPTB and hamstring) were compared, allografts were not analyzed separately due to limited sample size.
Imaging was conducted using both 1.5 T and 3.0 T MRI scanners, which could impact measurement consistency, particularly for small distances such as sTTTG. All evaluations were performed using standardized protocols and within a single PACS system, reducing interobserver variability. Although variations in knee flexion during MRI acquisition may affect sTTTG measurements, imaging was standardized near full extension, and knee flexion was additionally accounted for through statistical adjustment; however, residual effects cannot be fully excluded. The ALL subgroup analysis was limited by substantially imbalanced group sizes (n = 16 intact vs. n = 99 injured). While the sample size may have been sufficient to detect large between-group effects, it was underpowered to reliably detect small-to-moderate differences. Therefore, non-significant findings for sTTTG, knee flexion angle, and pivot-shift grade should be interpreted as inconclusive findings. Finally, no functional or patient-reported outcomes were included, as this was beyond the scope of the present imaging-based analysis. Moreover, the proposed biomechanical interpretations are not supported by direct experimental or in vivo validation and should therefore be considered hypothesis-generating.

6. Conclusions

A decreased sTTTG distance was significantly associated with ACL graft failure, underscoring the relevance of sagittal tibial tubercle positioning in ACL biomechanics. While not an independent clinical decision-making tool, sTTTG appears relevant to graft failure and may be considered in future risk assessment strategies.

Author Contributions

Conceptualization, S.S., C.B.G.L., D.F. and C.L.; Data curation, S.S., C.B.G.L. and D.F.; Formal analysis, S.S. and C.B.G.L.; Investigation, S.S. and D.F.; Methodology, A.D. and C.A.J.; Resources, C.A.J. and C.L.; Project administration, C.L.; Writing—original draft preparation, S.S., C.B.G.L. and D.F.; Writing—review and editing, A.D., C.A.J. and C.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Mass General Brigham Human Research Committee (protocol no. 2020P003747; date of approval: 23 December 2020).

Informed Consent Statement

Patient consent was waived by the institutional ethics committee due to the retrospective analysis. All patient data were de-identified to ensure confidentiality.

Data Availability Statement

The datasets generated and analyzed during the current study are not publicly available due to ethical and data protection restrictions.

Acknowledgments

During the preparation of this work, the authors used ChatGPT 4o ( OpenAI, USA) in order to improve grammar and style. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication. For the publication fee we acknowledge financial support by Heidelberg University.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Sanders, T.L.; Maradit Kremers, H.; Bryan, A.J.; Kremers, W.K.; Levy, B.A.; Dahm, D.L.; Stuart, M.J.; Krych, A.J. Incidence of and Factors Associated with the Decision to Undergo Anterior Cruciate Ligament Reconstruction 1 to 10 Years After Injury. Am. J. Sports Med. 2016, 44, 1558–1564. [Google Scholar] [CrossRef] [PubMed]
  2. Widner, M.; Dunleavy, M.; Lynch, S. Outcomes Following ACL Reconstruction Based on Graft Type: Are all Grafts Equivalent? Curr. Rev. Musculoskelet. Med. 2019, 12, 460–465. [Google Scholar] [CrossRef]
  3. Arnold, M.P.; Calcei, J.G.; Vogel, N.; Magnussen, R.A.; Clatworthy, M.; Spalding, T.; Campbell, J.D.; Bergfeld, J.A.; Sherman, S.L. ACL Study Group survey reveals the evolution of anterior cruciate ligament reconstruction graft choice over the past three decades. Knee Surg. Sports Traumatol. Arthrosc. 2021, 29, 3871–3876. [Google Scholar] [CrossRef] [PubMed]
  4. Kemler, B.; Coladonato, C.; Sonnier, J.H.; Campbell, M.P.; Darius, D.; Erickson, B.J.; Tjoumakaris, F.P.; Freedman, K.B. Evaluation of Failed ACL Reconstruction: An Updated Review. Open Access J. Sports Med. 2024, 15, 29. [Google Scholar] [CrossRef]
  5. Kaeding, C.C.; Aros, B.; Pedroza, A.; Pifel, E.; Amendola, A.; Andrish, J.T.; Dunn, W.R.; Marx, R.G.; Mccarty, E.C.; Parker, R.D.; et al. Allograft versus autograft anterior cruciate ligament reconstruction: Predictors of failure from a moon prospective longitudinal cohort. Sports Health 2011, 3, 73–81. [Google Scholar] [CrossRef]
  6. Lucidi, G.A.; Roberti di Sarsina, T.; Zaffagnini, S. Editorial Commentary: The Number One Cause of Anterior Cruciate Ligament Reconstruction Graft Failure Is a Misplaced Femoral Tunnel: Over-the-Top Technique Plus Lateral Extra-Articular Tenodesis Is Recommended. Arthrosc.—J. Arthrosc. Relat. Surg. 2024, 40, 435–437. [Google Scholar] [CrossRef]
  7. Wright, R.W.; Huston, L.J.; Haas, A.K.; Spindler, K.P.; Nwosu, S.K.; Allen, C.R.; Anderson, A.F.; Cooper, D.E.; DeBerardino, T.M.; Dunn, W.R.; et al. Effect of graft choice on the outcome of revision anterior cruciate ligament reconstruction in the multicenter ACL revision study (MARS) cohort. Am. J. Sports Med. 2014, 42, 2301–2310. [Google Scholar] [CrossRef]
  8. Chen, Y.; Tian, W.; Yuan, M.; Yang, H.; Lv, F.; Lv, F.; Li, J. Ratio of Tibial Tubercle–Trochlear Groove Distance to Patellar Width as a Predictor of Patellar Dislocation: Analysis of Individualized Tibial Tubercle Lateralization Parameters. Orthop. J. Sports Med. 2024, 12, 1–9. [Google Scholar] [CrossRef]
  9. Lin, K.M.; James, E.W.; Aitchison, A.H.; Schlichte, L.M.; Wang, G.; Green, D.W. Increased tibiofemoral rotation on MRI with increasing clinical severity of patellar instability. Knee Surg. Sports Traumatol. Arthrosc. 2021, 29, 3735–3742. [Google Scholar] [CrossRef]
  10. Liu, J.; Wang, J.; Tao, L.; Liu, C.; Wang, Y.; Wei, B.; Li, P.; Bao, H.; Ma, B.; Qi, Y.; et al. Comparison of Tibial Tuberosity-Trochlear Groove (TT-TG) distances between different anterior cruciate ligament reconstructions: A retrospective clinical and imaging study. Technol. Health Care 2019, 27, 229. [Google Scholar] [CrossRef] [PubMed]
  11. Ackermann, J.; Bergheim, N.; Hartmann, M.; Vlachopoulos, L.; Fucentese, S.F. Trochlear Dysplasia Is Associated with Increased Sagittal Tibial Tubercle Trochlear-Groove Distance in Patients with Patellar Instability. Arthroscopy 2025, 41, 1002–1008. [Google Scholar] [CrossRef]
  12. Lansdown, D.A.; Christian, D.; Madden, B.; Redondo, M.; Farr, J.; Cole, B.J.; Yanke, A.B. The Sagittal Tibial Tubercle-Trochlear Groove Distance as a Measurement of Sagittal Imbalance in Patients with Symptomatic Patellofemoral Chondral Lesions. Cartilage 2021, 13, 449S–455S. [Google Scholar] [PubMed]
  13. Tanaka, M.J.; D’Amore, T.; Elias, J.J.; Thawait, G.; Demehri, S.; Cosgarea, A.J. Anteroposterior distance between the tibial tuberosity and trochlear groove in patients with patellar instability. Knee 2019, 26, 1278–1285. [Google Scholar] [CrossRef]
  14. Floyd, E.R.; Carlson, G.B.; Monson, J.; LaPrade, R.F. Tibial Tubercle Preserving Anterior Closing Wedge Proximal Tibial Osteotomy and ACL Tunnel Bone Grafting for Increased Posterior Tibial Slope in Failed ACL Reconstructions. Arthrosc. Tech. 2021, 10, e2221. [Google Scholar] [CrossRef] [PubMed]
  15. Leite, C.B.G.; Bumberger, A.; Moreira da Silva, A.G.; Merkely, G.; Smith, R.; Helito, P.V.P.; Asnis, P.; Helito, C.P.; Lattermann, C. Increased internal tibiofemoral rotation is associated with anterolateral ligament injury and high-grade pivot-shift in ACL-injured patients. Knee Surg. Sports Traumatol. Arthrosc. 2025, 33, 4128–4135. [Google Scholar] [CrossRef] [PubMed]
  16. Leite, C.B.G.; Merkely, G.; Farina, E.M.; Smith, R.; Görtz, S.; Hazzard, S.; Asnis, P.; Lattermann, C. Effect of Tibiofemoral Rotation Angle on Graft Failure After Anterior Cruciate Ligament Reconstruction. Am. J. Sports Med. 2023, 51, 2291–2299. [Google Scholar] [CrossRef]
  17. Hefti, E.; Müller, W.; Jakob, R.P.; Stäubli, H.U. Evaluation of knee ligament injuries with the IKDC form. Knee Surg. Sports Traumatol. Arthrosc. 1993, 1, 226–234. [Google Scholar] [CrossRef]
  18. Ackermann, J.; Hartmann, M.; Berger, A.M.; Neopoulos, G.; Jud, L.; Vlachopoulos, L.; Fucentese, S.F. The Sagittal Tibial Tubercle Trochlear-Groove Distance Is Not Equivalent on Magnetic Resonance Imaging and Computed Tomography Measurements in Patients with Patellar Instability. Arthroscopy 2025, 41, 3392–3398. [Google Scholar] [CrossRef]
  19. Kaplan, D.J.; Mojica, E.S.; Ortega, P.F.; Triana, J.; Strauss, E.J.; Jazrawi, L.M.; Gonzalez-Lomas, G. Posterior tibial tubercle measured by the sagittal TT-TG distance correlates with increased risk for patellofemoral chondral lesions. Knee Surg. Sports Traumatol. Arthrosc. 2022, 30, 3733–3741. [Google Scholar] [CrossRef]
  20. Hudek, R.; Schmutz, S.; Regenfelder, F.; Fuchs, B.; Koch, P.P. Novel measurement technique of the tibial slope on conventional MRI. Clin. Orthop. Relat. Res. 2009, 467, 2066–2072. [Google Scholar] [CrossRef]
  21. Schoettle, P.B.; Zanetti, M.; Seifert, B.; Pfirrmann, C.W.A.; Fucentese, S.F.; Romero, J. The tibial tuberosity-trochlear groove distance; a comparative study between CT and MRI scanning. Knee 2006, 13, 26–31. [Google Scholar] [CrossRef]
  22. Helito, P.V.P.; Helito, C.P.; Rodrigues, M.B. Anterolateral ligament MRI of the knee in ACL injuries: MRI abnormalities association with instability. Eur. Radiol. 2023, 33, 1456–1464. [Google Scholar] [CrossRef]
  23. Weiler, A.; Berndt, R.; Wagner, M.; Scheffler, S.; Schatka, I.; Gwinner, C. Tibial Slope on Conventional Lateral Radiographs in Anterior Cruciate Ligament-Injured and Intact Knees: Mean Value and Outliers. Am. J. Sports Med. 2023, 51, 2285–2290. [Google Scholar] [CrossRef] [PubMed]
  24. Zeng, C.; Borim, F.M.; Lording, T. Increased posterior tibial slope is a risk factor for anterior cruciate ligament injury and graft failure after reconstruction: A systematic review. J. ISAKOS 2025, 12, 100854. [Google Scholar] [CrossRef] [PubMed]
  25. Bernhardson, A.S.; Aman, Z.S.; Dornan, G.J.; Kemler, B.R.; Storaci, H.W.; Brady, A.W.; Nakama, G.Y.; LaPrade, R.F. Tibial Slope and Its Effect on Force in Anterior Cruciate Ligament Grafts: Anterior Cruciate Ligament Force Increases Linearly as Posterior Tibial Slope Increases. Am. J. Sports Med. 2019, 47, 296–302. [Google Scholar] [CrossRef]
  26. Hung, Y.C.; Chuang, C.A.; Yao, S.Y.; Lin, K.Y.; Hung, S.F.; Chen, Y.J.; Chiu, C.H.; Ho, C.S.; Yang, C.P.; Chan, Y.S. Correlation between higher lateral tibial slope and inferior long term subjective outcomes following single bundle anterior cruciate ligament reconstruction. J. Orthop. Surg. Res. 2024, 19, 315. [Google Scholar] [CrossRef] [PubMed]
  27. Chen, K.J.; Lee, E.J.; Kliethermes, S.A.; Scerpella, T.A. Association of Tibial Tubercle–Trochlear Groove Distance with Risk of ACL Graft Failure. Orthop. J. Sports Med. 2023, 11, 1–9. [Google Scholar] [CrossRef]
  28. Ziegler, C.G.; DePhillipo, N.N.; Kennedy, M.I.; Dekker, T.J.; Dornan, G.J.; LaPrade, R.F. Beighton Score, Tibial Slope, Tibial Subluxation, Quadriceps Circumference Difference, and Family History Are Risk Factors for Anterior Cruciate Ligament Graft Failure: A Retrospective Comparison of Primary and Revision Anterior Cruciate Ligament Reconstructions. Arthrosc.—J. Arthrosc. Relat. Surg. 2021, 37, 195–205. [Google Scholar]
  29. Polat, A.E.; Polat, B.; Gürpınar, T.; Sarı, E.; Çarkçı, E.; Erler, K. Tibial tubercle–trochlear groove (TT–TG) distance is a reliable measurement of increased rotational laxity in the knee with an anterior cruciate ligament injury. Knee 2020, 27, 1601–1607. [Google Scholar] [CrossRef]
  30. Namiri, N.K.; Càliva, F.; Martinez, A.M.; Pedoia, V.; Lansdown, D.A. A More Posterior Tibial Tubercle (Decreased Sagittal Tibial Tubercle-Trochlear Groove Distance) Is Significantly Associated with Patellofemoral Joint Degenerative Cartilage Change: A Deep Learning Analysis. Arthroscopy 2023, 39, 1493–1501.e2. [Google Scholar] [CrossRef]
Surgeries 07 00068 g001
Figure 1. The sagittal tibial tubercle–trochlear groove (sTTTG) distance is determined by referencing two axial levels. (Top) The posterior condylar axis (solid line) and the deepest point of the trochlear groove are identified at the level of the femoral condyles. (Bottom) This reference is projected onto the level of the patellar tendon insertion at the tibial tubercle ( dashed line). The sTTTG is defined as the anteroposterior distance (yellow double arrow) between the deepest point of the trochlear cartilage and the most anterior point of the tibial tubercle, measured perpendicular to the posterior femoral condylar axis. Positive values indicate a tibial tubercle located posterior to the trochlear groove.
Figure 1. The sagittal tibial tubercle–trochlear groove (sTTTG) distance is determined by referencing two axial levels. (Top) The posterior condylar axis (solid line) and the deepest point of the trochlear groove are identified at the level of the femoral condyles. (Bottom) This reference is projected onto the level of the patellar tendon insertion at the tibial tubercle ( dashed line). The sTTTG is defined as the anteroposterior distance (yellow double arrow) between the deepest point of the trochlear cartilage and the most anterior point of the tibial tubercle, measured perpendicular to the posterior femoral condylar axis. Positive values indicate a tibial tubercle located posterior to the trochlear groove.
Surgeries 07 00068 g001
Surgeries 07 00068 g002
Figure 2. The knee flexion angle was defined as the angle subtended by the longitudinal axes of the femur and the tibia. The femoral axis was determined by connecting the midpoints of the femoral shaft, while the tibial axis was defined by the line connecting the midpoints of the proximal tibial diaphysis.
Figure 2. The knee flexion angle was defined as the angle subtended by the longitudinal axes of the femur and the tibia. The femoral axis was determined by connecting the midpoints of the femoral shaft, while the tibial axis was defined by the line connecting the midpoints of the proximal tibial diaphysis.
Surgeries 07 00068 g002
Table 1. Patient characteristics adapted from Leite et al. [16]. ACLR, anterior cruciate ligament reconstruction; BMI, body mass index.
Table 1. Patient characteristics adapted from Leite et al. [16]. ACLR, anterior cruciate ligament reconstruction; BMI, body mass index.
Characteristics Intact ACLR
(n = 151 )		ACLR Failure
(n = 151)		 
Mean ± SD (Range)Mean ± SD (Range)p
Age (years)25.9 ± 10 (15–59)25.7 ± 10.4 (13–59)0.706
BMI (kg/m2)25.7 ± 4 (17.2–42.2)25.1 ± 3.3 (17.7–34.8)0.221
N (%)N (%)
Sex >0.999
Male87 (57.6%)87 (57.6%)
Female64 (42.4%)64 (42.4%)
Side affected 0.107
Left83 (55%)68 (45%)
Right68 (45%)83 (55%)
Type of graft 0.250
Allograft27 (17.9%)30 ( 19.9%)
Hamstring tendon autograft39 (25.8%)50 (33.1%)
Bone–patellar tendon–bone autograft85 (56.3%)71 (47%)
Meniscus injury86 (57%)86 (57%)>0.999
Table 2. Multivariable linear regression model of factors associated with sTTTG. Bold p value indicates statistical significance (p < 0.05). TFR, tibiofemoral rotation angle; TT-TG, tibial tubercle–trochlear groove; PTS, posterior tibial slope.
Table 2. Multivariable linear regression model of factors associated with sTTTG. Bold p value indicates statistical significance (p < 0.05). TFR, tibiofemoral rotation angle; TT-TG, tibial tubercle–trochlear groove; PTS, posterior tibial slope.
β CoefficientStandard Errorp
Intercept4.261.480.004
TFR−0.140.070.051
TT-TG0.030.070.713
Medial PTS−0.040.150.771
Lateral PTS−0.370.160.022
Knee flexion0.170.05<0.001
R2 = 0.11
Table 3. Imaging measurements of subgroup analysis (ALL injury). Bold p value indicates statistical significance (p < 0.05). ALL, anterolateral ligament; sTTTG, sagittal tibial tubercle–trochlear groove; TFR, tibiofemoral rotation angle.
Table 3. Imaging measurements of subgroup analysis (ALL injury). Bold p value indicates statistical significance (p < 0.05). ALL, anterolateral ligament; sTTTG, sagittal tibial tubercle–trochlear groove; TFR, tibiofemoral rotation angle.
 Intact ALL
(n = 16 )		Injured ALL
(n = 99)		 
Mean ± SD (Range)Mean ± SD (Range)p
sTTTG (mm)3.04 ± 3.73 (−3.48–9.37)1.71 ± 4.75 (−12.5–11.6)0.218
TFR (°)4.79 ± 3.37 (−1–15)2.06 ± 2.69 (−3–7)0.003
Knee flexion (°)7.44 ± 4.83 (0–20)7.36 ± 4.91 (−3–27)0.802
N (%)N (%)
Pivot Shift Grade 0.413
101
21689
309
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Schmidt, S.; Leite, C.B.G.; Franco, D.; Darwich, A.; Jacobs, C.A.; Lattermann, C. Effect of Sagittal TTTG on Graft Failure After Anterior Cruciate Ligament Reconstruction. Surgeries 2026, 7, 68. https://doi.org/10.3390/surgeries7020068

AMA Style

Schmidt S, Leite CBG, Franco D, Darwich A, Jacobs CA, Lattermann C. Effect of Sagittal TTTG on Graft Failure After Anterior Cruciate Ligament Reconstruction. Surgeries. 2026; 7(2):68. https://doi.org/10.3390/surgeries7020068

Chicago/Turabian Style

Schmidt, Sebastian, Chilan B. G. Leite, Domenico Franco, Ali Darwich, Cale A. Jacobs, and Christian Lattermann. 2026. "Effect of Sagittal TTTG on Graft Failure After Anterior Cruciate Ligament Reconstruction" Surgeries 7, no. 2: 68. https://doi.org/10.3390/surgeries7020068

APA Style

Schmidt, S., Leite, C. B. G., Franco, D., Darwich, A., Jacobs, C. A., & Lattermann, C. (2026). Effect of Sagittal TTTG on Graft Failure After Anterior Cruciate Ligament Reconstruction. Surgeries, 7(2), 68. https://doi.org/10.3390/surgeries7020068

Article Metrics

Back to TopTop