Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee

Learning curve for combined reconstruction of the anterolateral and anterior cruciate ligaments: a report of 108 cases with a single surgeon

BACKGROUND

Anterior cruciate ligament (ACL) rupture is a common lesion among young sports players, for whom isolated surgical repair remains the gold standard. However, there is a high risk of re-rupture after ACL reconstruction. Recent results of ACL reconstruction combined with reconstruction of the anterolateral ligament (ALL) have shown a significant decrease in this risk. However, as with all new techniques, this requires a learning curve.

HYPOTHESIS

Combined reconstruction of the ACL and ALL would have a short learning curve, be reproducible and have no specific complications.

PATIENTS AND METHODS

This retrospective study included the first 108 patients who underwent combined ACL and ALL reconstruction by a single surgeon. The patients were divided into four similar sized chronological groups (groups 1-4). Tourniquet time and associated procedures were analysed. The results of the IKDC subjective knee evaluation, Lysholm, KOOS and SANE functional scores were collected postoperatively at 1-year through an online database. The position of the femoral tunnel was evaluated using the quadrant method of Bernard and Hertel.

RESULTS

A significant improvement in the position of the femoral tunnel in the proximo-distal axis was observed between groups 1 and 4 (p < 0.01), as well as between groups 3 and 4 (p < 0.001). The Lysholm functional score was significantly higher in group 4 at 1-year (difference between groups 1 and 4 (+3.2 (1.4-5.1), p = 0.017)). The tourniquet time decreased significantly between the first group and groups 2, 3 and 4 (p < 0.002).

DISCUSSION

Precise positioning of the femoral tunnel in the proximo-distal axis is important during combined reconstruction of the ACL and ALL. The combined technique had a rapid learning curve, was reproducible, and resulted in a rapid decrease in the tourniquet time.

LEVEL OF EVIDENCE

III; observational study.

Virtual triple-bundle ACL graft via femoral tunnels behind the resident's ridge on 3D CT demonstrates equivalent orientation to native ACL

Purpose

To clarify the femoral tunnel location for a virtual anterior cruciate ligament (ACL) graft to simulate the native ACL.

Methods

Three-dimensional (3D) computed tomography (CT) and magnetic resonance imaging (MRI) were obtained in 14 normal knees in full extension. Two types of virtual triple bundle ACL grafts (VACLG) were created. In one type, the femoral tunnels for anteromedial bundle (AM = AMM/anteromedial bundle medial part + AML/anteromedial bundle lateral part) and posterolateral bundle (PL) were positioned behind the resident's ridge (RR) based on the bone landmark strategy (BR-VACLG group). In the other type, the tunnels were placed on the RR (OR-VACLG group). VACLG was displayed as three straight lines by connecting the two centres of the femoral attachment areas of AM and PL to those of the three tibial footprints of AMM, AML and PL attachments on 3D CT, and then superimposed on MRI. The ACL/ACL graft-the tibial plateau (ACL-TP) angles were compared among normal ACL (N-ACL), BR-VACLG and OR-VACLG.

Results

The mean ACL-TP angles of N-ACL, BR-VACLG and OR-VACLG were 74.4 ± 3.4°, 75.2 ± 4.5° and 68.7 ± 5.0° for AMM, 81.9 ± 3.8°, 82.9 ± 5.1° and 76.3 ± 4.0° and for AML, 71.1 ± 6.4°, 70.0 ± 7.2° and 61.0 ± 4.7° for PL on the oblique-coronal slices; 55.3 ± 4.9° 53.9 ± 4.4° and 50.5 ± 4.3° for AMM; 54.9 ± 4.5°, 54.7 ± 2.6° and 50.7 ± 3.2° for AML; 51.4 ± 3.3°, 51.2 ± 2.4° and 48.1 ± 2.0° for PL on the oblique-sagittal slices. There was no significant difference in the angles between N-ACL and BR-VACLG, while those of AMM and PL in OR-VACLG were significantly lower compared to N-ACL.

Conclusion

The virtual triple bundle ACL graft via femoral tunnels behind the RR on 3D CT shows equivalent orientation to the native ACL on MRI in full extension.

Level of Evidence

Level III.

Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction Shows Superior Graft Remodeling, Maturation, and Stability Compared With Isolated Anterior Cruciate Ligament Reconstruction

PURPOSE

To compare graft remodeling, as measured by magnetic resonance imaging (MRI), and clinical outcomes between patients who underwent isolated anterior cruciate ligament reconstruction (ACLR) versus combined anterior cruciate ligament and anterolateral ligament reconstruction (ACLR + ALLR).

METHODS

A retrospective review was conducted on patients who underwent primary ACLR with quadruple hamstring grafts between January 2019 and March 2022, with a minimum follow-up period of 2 years. Patients were categorized into two groups based on the addition of ALLR with tibialis anterior allografts: an isolated ACLR group and an ACLR + ALLR group. Graft ligamentization was assessed using signal-to-noise quotient (SNQ) values obtained from postoperative MRI scans, with lower SNQ values indicating superior graft remodeling. Clinical outcomes were evaluated through knee stability tests (pivot-shift test, side-to-side laxity), functional outcomes, and graft retear rates. The minimal clinically important difference (MCID) for the clinical scores was calculated using the distribution-based method of a half standard deviation of the delta (difference between postoperative and baseline values). Regression analyses identified potential predictive factors for inferior ACL graft remodeling.

RESULTS

A total of 122 patients in the isolated ACLR group and 54 in the ACLR + ALLR group were evaluated. The mean follow-up periods were similar between the groups (34.1 ± 7.4 months vs 36.4 ± 9.0 months; P = .755). The mean SNQ values were significantly lower in the ACLR + ALLR group compared to the isolated ACLR group (2.8 ± 1.6 vs 4.7 ± 3.5 mm, respectively; P = .001). Inferior ACL graft maturity was associated with an increased posterior tibial slope (P = .016), narrow notch width (P =.018), and concomitant medial meniscal lesion (P = .017). At the final evaluation, the ACLR + ALLR group demonstrated better rotational stability as indicated by the residual pivot-shift test (P = .005). No statistically significant differences were observed between the two groups in side-to-side laxity, functional outcomes, or graft retear rates. There were no differences in the percentage of patients achieving MCID for the International Knee Documentation Committee subjective score between the groups (P = .536).

CONCLUSIONS

Combined ACLR and ALLR resulted in superior graft remodeling, demonstrated by a mean SNQ value that was 1.9 lower than in isolated ACLR, along with improved rotational stability.

LEVEL OF EVIDENCE

Level III, retrospective, nonrandomized, comparative therapeutic study.

Nonanatomic femoral tunnel placement increases the risk of subsequent meniscal surgery after ACLR: Part II-Patients without recurrent ACL injury

PURPOSE

The purpose of this study was to identify risk factors for subsequent meniscal surgery following anterior cruciate ligament (ACL) reconstruction (ACLR) in patients without recurrent ACL injury.

METHODS

Patients aged ≥14 years who underwent primary ACLR with minimum 1-year follow-up and without recurrent ACL injury were retrospectively reviewed. Patient demographics and surgical data at the time of ACLR were collected. Postoperative radiographs were used to measure femoral and tibial tunnel position, and posterior tibial slope. Univariate and multivariate analyses were performed to identify risk factors for subsequent meniscal surgery.

RESULTS

Of 629 ACLRs that fulfilled the inclusion criteria, subsequent meniscal surgery was performed in 65 [10.3%] patients. Multivariate analysis revealed that medial meniscal repair at the time of ACLR, younger age, anterior femoral tunnel position and distal femoral tunnel position were significantly associated with subsequent meniscal surgery (p < 0.001, p = 0.016, p = 0.015, p = 0.035, respectively). The frequency of femoral tunnel placement >10% outside of the literature-established anatomic position was significantly higher in those who underwent subsequent meniscal surgery compared to those who did not (38.3% vs. 20.3%, p = 0.006). Posterior tibial slope and ACL graft type were not significantly associated with subsequent meniscal surgery.

CONCLUSION

Medial meniscal repair at the time of ACLR, younger age and nonanatomic femoral tunnel placement were risk factors for subsequent meniscal surgery in patients without recurrent ACL injury. Femoral tunnel placement <10% outside of the native anatomic position is important to reduce the risk of subsequent meniscal surgery.

LEVEL OF EVIDENCE

Level IV.

Proximally positioned femoral grafts decrease passive anterior tibial subluxation in anterior cruciate ligament reconstruction using a posterior trans-septal portal

PURPOSE

To compare the anterior and posterior trans-septal (TS) portal approaches in anterior cruciate ligament reconstruction (ACLR) by evaluating femoral tunnel positioning and passive anterior tibial subluxation (PATS).

METHODS

A total of 205 patients who underwent primary ACLR using the outside-in technique between March 2018 and December 2021 were retrospectively enrolled. Patients were classified into two groups based on the viewing techniques: the anterior group was treated using anteromedial or anterolateral portals (n = 155), and the TS group was treated using posterior TS portal (n = 55). The relative locations of the femoral tunnel were evaluated using the deep-shallow planes (X-axis) and superior-inferior planes (Y-axis) with the quadrant method in the lateral femoral condyle on a 3-dimensional computed tomography image. Anterior tibial subluxation for the lateral and medial compartments relative to the femoral condyles was evaluated as measured on magnetic resonance imaging. Knee laxity was assessed using the pivot-shift test and stress radiography.

RESULTS

In the posterior TS group, the femoral tunnel was usually located deeper on the X-axis and more superior on the Y-axis, which corresponds to a more proximal position, than in the anterior group (deeper on the X-axis and superior on the Y-axis). Moreover, the femoral tunnel locations in this group were more compactly distributed than those in the anterior group. The TS group showed significantly better reduction of postoperative PATS in the lateral compartments than the anterior group (anterior group vs. TS group: lateral compartment, 3.2 ± 3.1 vs. 4.5 ± 3.2 mm; p = .016). Significantly better results were found in the TS group for knee stability as assessed by the pivot-shift grade (p = .044); however, there were no significant differences between the two groups with respect to patient-reported outcome measures (p > .05) and other complications (p = .090).

CONCLUSION

Our results suggest that positioning the femoral tunnel using the posterior TS portal approach may lead to better outcomes in terms of PATS and rotational stability compared to the anterior portal approach in ACLR.

Comparison of femoral tunnel position and knee function in anterior cruciate ligament reconstruction: a retrospective cohort study using measuring-fluoroscopy method versus bony marker method

BACKGROUND

Previous studies have shown that surgical technique errors especially the wrong bone tunnel position are the primary reason for the failure of anterior cruciate ligament (ACL) reconstruction. In this study, we aimed to compare the femoral tunnel position and impact on knee function during the ACL reconstruction using measuring combined with fluoroscopy method and bony marker method for femoral tunnel localization.

METHODS

A retrospective cohort study of patients undergoing ACL reconstruction using the bony marker method or measuring combined with fluoroscopy for femoral tunnel localization was conducted between January 2015 and January 2020. A second arthroscopic exploration was performed more than 1 year after surgery. Data regarding patient demographics, the femoral tunnel position, results of the Lysholm score, the International Knee Documentation Committee (IKDC) score, KT-1000 side-to-side difference, pivot shift grade, and Lachman grade of the knee were collected.

RESULTS

A total of 119 patients were included in the final cohort. Of these, 42 cases were in the traditional method group, and 77 cases were in the measuring method group. The good tunnel position rate was 26.2% in the traditional method group and 81.8% in the measuring method group (p < 0.001). At the final follow-up, the Lysholm and IKDC scores were significantly greater in the measuring method group than the traditional method group (IKDC: 84.9 ± 8.4 vs. 79.6 ± 6.4, p = 0.0005; Lysholm: 88.8 ± 6.4 vs. 81.6 ± 6.4, p < 0.001). Lachman and pivot shift grades were significantly greater in the measuring method group (p = 0.01, p = 0008). The results of KT-1000 side-to-side differences were significantly better in the measuring method group compared with those in the traditional method group (p < 0.001).

CONCLUSIONS

The combination of the measuring method and intraoperative fluoroscopy resulted in a concentrated tunnel position on the femoral side, a high rate of functional success, improved knee stability, and a low risk of tunnel deviation. This approach is particularly suitable for surgeons new to ACL reconstructive surgery.

Surgical Techniques in Primary ACL Reconstruction: Getting It Right the First Time

The ideal anterior cruciate ligament reconstruction (ACLR) is an individualized anatomic approach aimed at restoring the native structure and function of the knee. Surgeons are tasked with difficult decisions during operative planning, including the optimal graft choice for the patient and appropriate anatomic tunnel placement. Special considerations should additionally be given for skeletally immature patients and those at high-risk for failure, including younger, active patients participating in pivoting sports. The purpose of this review is to provide an overview of the individualized approach to ACLR, including the necessary preoperative and operative considerations to optimize patient outcomes.

App-based analysis of the femoral tunnel position in ACL reconstruction using the quadrant method

PURPOSE

The purpose of this study was to examine the intra- and interobserver variability of an app-based analysis of the femoral tunnel position using the quadrant method in primary anterior cruciate ligament reconstruction.

MATERIALS AND METHODS

Between 12/2020 und 12/2021 50 patients who underwent primary anterior cruciate ligament reconstruction were included in this retrospective study. Intraoperative strictly lateral fluoroscopic images of the knee with marked femoral tunnel were analyzed by four observers using the quadrant method. For retest reliability analysis, measurements were repeated once by 2 observers after 4 weeks.

RESULTS

The femoral tunnel position of all included patients averaged 27.86% in the depth relation and 15.61% in the height relation. Statistical analysis showed an almost perfect intra- and interobserver reliability in the depth and height relation. The ICC was 0.92 in the depth relation and 0.84 in the height relation. The Pearson's correlation coefficient in the depth and height relation of observer 1 (0.94/0.81) was only slightly different from the Pearson's correlation coefficient of observer 2 (0.92/0.85). The app-based tunnel analysis took on average 59 ± 16 s per measurement.

CONCLUSION

The femoral tunnel analysis with the app-based quadrant method has an almost perfect intra- and interobserver reliability. By smartphone camera, a fast and highly accurate, if necessary also intraoperative, control of the tunnel position can be performed.

LEVEL OF EVIDENCE

Level 3-diagnostic retrospective cohort study.

Evaluating femoral graft placement using three-dimensional magnetic resonance imaging in the reconstruction of the anterior cruciate ligament via independent or transtibial drilling techniques: a retrospective cohort study

PURPOSE

Anterior cruciate ligament (ACL) reconstruction is a common surgical procedure, yet failure still largely occurs due to nonanatomically positioned grafts. The purpose of this study was to retrospectively evaluate patients with torn ACLs before and after reconstruction via 3D MRI and thereby assess the accuracy of graft position on the femoral condyle.

METHODS

Forty-one patients with unilateral ACL tears were recruited. Each patient underwent 3D MRI of both knees before and after surgery. The location of the reconstructed femoral footprint relative to the patient's native footprint was compared.

RESULTS

Native ACL anatomical location of the native ACL had a significant impact on graft position. Native ACLs that were previously more anterior yielded grafts that were more posterior (3.70 ± 1.22 mm, P = 0.00018), and native ACL that were previously more proximal yielded grafts that were more distal (3.25 ± 1.09 mm, P = 0.0042). Surgeons using an independent drilling method positioned 76.2% posteriorly relative to the native location, with a mean 0.1 ± 2.8 mm proximal (P = 0.8362) and 1.8 ± 3.0 mm posterior (P = 0.0165). Surgeons using a transtibial method positioned 75% proximal relative to the native location, with a mean 2.2 ± 3.0 mm proximal (P = 0.0042) and 0.2 ± 2.6 mm posterior (P = 0.8007). These two techniques showed a significant difference in magnitude in the distal-proximal axis (P = 0.0332).

CONCLUSION

The femoral footprint position differed between the native and reconstructed ACLs, suggesting that ACL reconstructions are not accurate. Rather, they are converging to a normative reference point that is neither anatomical nor isometric.

Incidence of Convergence Between Distally and Anteriorly Oriented ALL Femoral Tunnels and ACL Femoral Tunnels in Combined ACL and ALL Reconstruction: 3-Dimensional Computed Tomography Analysis of 227 Patients

BACKGROUND

Adjusting the direction of the anterolateral ligament (ALL) femoral tunnel is suggested to avoid tunnel convergence during anterior cruciate ligament (ACL) reconstruction. Yet, there has been no in vivo clinical study reporting the effect of changing the direction of the ALL tunnel on the incidence of convergence with the ACL tunnel.

PURPOSE

To report the incidence of convergence between the ACL femoral tunnel and a distally and anteriorly directed ALL femoral tunnel and to determine a safe distal angle and anterior angle.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 227 patients undergoing concomitant ALL and anatomic single-bundle ACL reconstruction between January 2020 and December 2022 were retrospectively reviewed. The tunnel convergence rate, angular orientation of the tunnels, and distance between tunnels were obtained using postoperative computed tomography. The patients were grouped based on the direction of the ALL tunnel (transverse vs distal anterior) and the presence of tunnel convergence (convergence vs no convergence).

RESULTS

The overall tunnel convergence rate was 53.3% (121/227 patients). Tunnel convergence was observed less frequently in the distal anterior group (33.7%) than in the transverse group (65.2%) (P < .001). The no convergence group showed an ALL tunnel oriented more distally (20.2°± 11.1°) and anteriorly (19.5°± 10.2°) compared with the convergence group (8.7°± 6.5° and 6.9°± 5.3°, respectively) (P = .005 and P = .008, respectively). There were no cases of tunnel convergence for ALL tunnels >24.3° distally and >25.5° anteriorly. There was no difference in the angle of the ACL femoral tunnel between all groups.

CONCLUSION

A distally and anteriorly directed ALL femoral tunnel reduced the incidence of convergence with the ACL femoral tunnel. A distal angle >24.3° and an anterior angle >25.5° of an ALL tunnel are suggested to safely avoid convergence with the ACL tunnel.

Anteromedial Portal versus Transtibial Drilling Techniques for Femoral Tunnel Placement in Arthroscopic Anterior Cruciate Ligament Reconstruction: Radiographic Evaluation and Functional Outcomes at 2 Years Follow-Up

The aim of this study was to compare the functional and radiographic outcomes of arthroscopic single-bundle anterior cruciate ligament reconstruction (ACLR) using either the anteromedial (AM) portal technique or transtibial (TT) technique. We identified 404 patients who underwent arthroscopic ACLR by a single surgeon between January 2006 and December 2016 at our institution. The TT portal was utilized in femoral tunnel drilling in 202 patients (TT group) while the AM portal was used in 202 patients (AM group). The mean postoperative follow-up duration was 26 months (range: 24-33 months). Postoperative radiographic femoral and tibial tunnel positions were assessed by two independent observers. Functional outcomes were evaluated with Tegner, Lysholm, and Knee Injury and Osteoarthritis Outcome score (KOOS) scores. On the anteroposterior plain radiographs, the mean femoral tunnel position relative to the lateral femoral condyle was 46.8% for the AM group versus 48.6% in the TT group, respectively (p=0.003). The mean graft inclination angle was 31.9° and 22° in the AM and TT groups, respectively (p<0.0001). On the lateral radiographs, the mean femoral tunnel placement across Blumensaat's line in relation to the anterior femoral cortex was 84% in the AM group while it was 78% in the TT group (p<0.0001). At 2 years postoperatively, there were no significant differences in the mean Tegner, Lysholm, and KOOS scores between the two patient groups. The graft failure rate at 2 years follow-up was 4.5% (n=9) in the AM group while it was 2.5% (n=5) in the TT group (p=0.2). Femoral tunnel placement was more anatomical with the AM portal technique compared with the TT technique. However, there was no significant difference in postoperative functional outcomes between the two patient groups. The AM portal technique appears to have a higher graft failure rate. This might be attributed to increased graft loading in an anatomical position.

Usefulness of 3-Dimensional Computed Tomography Assessment of Femoral Tunnel after Anterior Cruciate Ligament Reconstruction

Positioning of the femoral tunnel during anterior cruciate ligament (ACL) reconstruction is the most crucial factor for successful procedure. Owing to the inter-individual variability in the intra-articular anatomy, it can be challenging to obtain precise tunnel placement and ensure consistent results. Currently, the three-dimensional (3D) reconstruction of computed tomography (CT) scans is considered the best method for determining whether femoral tunnels are positioned correctly. Postoperative 3D-CT feedback can improve the accuracy of femoral tunnel placement. Precise tunnel formation obtained through feedback has a positive effect on graft maturation, graft failure, and clinical outcomes after surgery. However, even if femoral tunnel placement on 3D CT is appropriate, we should recognize that acute graft bending negatively affects surgical results. This review aimed to discuss the implementation of 3D-CT evaluation for predicting postoperative outcomes following ACL re-construction. Reviewing research that has performed 3D CT evaluations after ACL reconstruction can provide clinically significant evidence of the formation of ideal tunnels following anatomic ACL reconstruction.

Femoral Tunnel Position Affects Postoperative Femoral Tunnel Widening after Anterior Cruciate Ligament Reconstruction with Tibialis Anterior Allograft

This study aims to identify potential factors for both femoral and tibial tunnel widening (TW) and to investigate the effect of TW on postoperative outcomes after anterior cruciate ligament (ACL) reconstruction with a tibialis anterior allograft. A total 75 patients (75 knees) who underwent ACL reconstruction with tibialis anterior allografts were investigated between February 2015 and October 2017. TW was calculated as the difference in tunnel widths between the immediate and 2-year postoperative measurements. The risk factors for TW, including demographic data, concomitant meniscal injury, hip-knee-ankle angle, tibial slope, femoral and tibial tunnel position (quadrant method), and length of both tunnels, were investigated. The patients were divided twice into two groups depending on whether the femoral or tibial TW was over or less than 3 mm. Pre- and 2-year follow-up outcomes, including the Lysholm score, International Knee Documentation Committee (IKDC) subjective score, and side-to-side difference (STSD) of anterior translation on stress radiographs, were compared between TW ≥ 3 mm and TW < 3 mm. The femoral tunnel position depth (shallow femoral tunnel position) was significantly correlated with femoral TW (adjusted R² = 0.134). The femoral TW ≥ 3 mm group showed greater STSD of anterior translation than the femoral TW < 3 mm group. The shallow position of the femoral tunnel was correlated with the femoral TW after ACL reconstruction using a tibialis anterior allograft. A femoral TW ≥ 3 mm showed inferior postoperative knee anterior stability.

The apex of the deep cartilage is a stable landmark to evaluate the femoral tunnel position in ACL reconstruction

PURPOSE

To develop a simple and effective method for evaluating the femoral tunnel position using the apex of the deep cartilage (ADC) as the landmark.

METHODS

A total of 52 patients who underwent arthroscopic ACL reconstruction were recruited between June and September 2021. The femoral tunnel was placed on the central point of the anteromedial footprint with an accessory anteromedial and a high anterolateral portal. Then, the length from the ADC to the shallow cartilage margin (L₁) and to the center of the femoral tunnel (l₁), as well as the center to the low cartilage margin (H₁, intraoperative height), was measured under arthroscopy and on postoperative CT scans (L₂, l₂ and H₂). Moreover, intraoperative and postoperative cartilage ratios were equivalent to l₁/L₁ and l₂/L₂, respectively. Linear regression, Pearson correlation and Bland-Altman analysis were performed to evaluate the consistency between these two measurements of cartilage ratio (l/L) and height (H).

RESULTS

The mean age at the time of surgery was 28.7 years; 42 patients were male, and 17 patients were hurt in the left knee among 52 patients. The intraoperative cartilage ratio was 0.37 ± 0.04, and the height was 8.1 ± 1.1 mm with almost perfect inter-observer reproducibility. After the surgery, the cartilage ratio and height were measured as 0.39 ± 0.04 and 8.2 ± 1.3 mm on 3D-CT, respectively, with almost perfect intra- and inter-observer reproducibility. Significant positive correlations and linear regression were detected in the cartilage ratio (r = 0.844, p < 0.001), and height (r = 0.926, p < 0.001) intraoperatively and postoperatively. The Bland-Altman plot also showed excellent consistency between arthroscopy and 3D-CT.

CONCLUSIONS

The ADC is a good landmark in the assessment of femoral tunnel position, with excellent consistency between intraoperative arthroscopic measurements and postoperative 3D-CT.

CLINICALTRIALS

gov Identifier: NCT04937517.

LEVEL OF EVIDENCE

Level III.

Global research status of anterior cruciate ligament reconstruction: a bibliometric analysis

Purpose

The aim of this study is to comprehensively analyze the publications of anterior cruciate ligament reconstruction (ACLR) research and display the current research status in this field.

Methods

Articles regarding ACLR research published before October 7, 2021, were downloaded from the Web of Science Core Collection. Excel 2016 and Bibliometric website were used to analyze the annual article trends and international cooperation network. CiteSpace V and VOSviewer were used to perform co-occurrence and citation analyses for journals, institutions, authors, cocitation authors and keywords. Burst keyword detection was also performed with CiteSpace V.

Results

A total of 12 223 ACLR articles were identified. The American Journal of Sports Medicine (1636 publications, 92,310 citations), the Pennsylvania Commonwealth System of Higher Education (624 publications, 25,304 citations) and Freddie H. Fu (321 publications, 15,245 citations) were journals, institutions and authors with the most publications and citations, respectively. Patellar tendon was the keyword with the most occurrences (1618 times) and return to sport was the keyword with the most burst strength (burst strength: 46.99).

Conclusion

ACLR-related publications showed a rapid increasing trend since 1990. A large number of articles have been published by authors from different institutions and countries, some of which have gained great academic influence. Based on keyword analysis, patellar tendon is identified as the research hotspot and return to sport is identified as the current research frontier.

Finite Element Analysis and Experimental Validation of the Anterior Cruciate Ligament and Implications for the Injury Mechanism

This study aimed to establish a finite element model that vividly reflected the anterior cruciate ligament (ACL) geometry and investigated the ACL stress distribution under different loading conditions. The ACL’s three-dimensional finite element model was based on a human cadaveric knee. Simulations of three loading conditions (134 N anterior tibial load, 5 Nm external tibial torque, 5 Nm internal tibial torque) on the knee model were performed. Experiments were performed on a knee specimen using a robotic universal force/moment sensor testing system to validate the model. The simulation results of the established model were in good agreement with the experimental results. Under the anterior tibial load, the highest maximal principal stresses (14.884 MPa) were localized at the femoral insertion of the ACL. Under the external and internal tibial torque, the highest maximal principal stresses (0.815 MPa and 0.933 MPa, respectively) were mainly concentrated in the mid-substance of the ACL and near the tibial insertion site, respectively. Combining the location of maximum stress and the location of common clinical ACL rupture, the most dangerous load during ACL injury may be the anterior tibial load. ACL injuries were more frequently loaded by external tibial than internal tibial torque.

Computer-assisted navigation in ACL reconstruction improves anatomic tunnel placement with similar clinical outcomes

BACKGROUND

While the use of navigation systems in anterior cruciate ligament (ACL) reconstruction theoretically improves tunnel placement accuracy and clinical outcomes, the existing literature remains inconclusive. We aimed to evaluate the potential benefits of navigated ACL reconstruction on tunnel placement and clinical outcomes.

METHODS

In this retrospective study, we evaluated a cohort of patients who underwent conventional or navigated (OrthoPilot system) primary ACL reconstruction at our institution from June 2004 to October 2009. Anteroposterior and lateral radiographic knee assessments were evaluated to assess postoperative tunnel positioning. Clinical outcomes, including the International Knee Documentation Committee classification, Lysholm score, and Tegner score, were evaluated preoperatively and 1-year postoperatively. Radiographic and clinical outcomes were compared and analysed using independent 2-sample t-tests and Chi-square tests.

RESULTS

Sixty patients met the inclusion criteria and were included for analysis, comprising of 26 navigated and 34 conventional reconstructions. Postoperative radiographs showed no differences in tibial tunnel position between both groups, but a significantly smaller deviation from the recommended position in the navigated group (navigated: 5.96 %; conventional: 7.92 %; p = 0.008). Femoral tunnel placements in the navigated group were significantly more perpendicularly away from the Blumensaat line (navigated: 38.90 %; conventional: 31.94 %; p = 0.001), with a greater deviation from recommended position (navigated: 11.00 %; conventional: 6.94 %; p = 0.009). There were no differences in 1-year postoperative clinical outcomes (p > 0.05).

CONCLUSION

Navigated ACL reconstruction resulted in a more anatomic femoral tunnel placement and similar clinical outcomes as conventional reconstruction. Further research should be conducted to clarify the potential biomechanical and clinical impacts of navigated ACL reconstruction.

Graft isometry during anatomical ACL reconstruction has little effect on surgical outcomes

PURPOSE

To investigate the surgical outcomes of anatomical anterior cruciate ligament (ACL) reconstruction according to the graft isometry measured during surgery.

METHODS

Electrical medical records of patients who underwent an arthroscopic ACL reconstruction through the transportal technique using hamstring tendon autograft between 2012 and 2016 were retrospectively reviewed. The patients were classified into two groups based on the graft length change throughout the knee range of motion measured just before graft fixation (Group 1, graft length change ≤ 2 mm; Group 2, graft length change > 2 mm). Comparative analyses, including a non-inferiority trial, were performed regarding the clinical scores, knee laxity, and radiographic parameters between the groups.

RESULTS

A total of 67 patients were included in the study. The total change in the length of ACL graft throughout the knee range of motion was 1.4 ± 0.4 mm in Group 1 (range, 0.2-2.0 mm), and 3.0 ± 0.7 mm in Group 2 (range, 2.2-5.0 mm). Group 1 showed a relatively high (proximal) femoral tunnel and shallow (anterior) tibial tunnel compared to Group 2 (P < 0.001 and P = 0.028, respectively), but there were no apparent differences in the macroscopic view. There were no statistically significant differences in the clinical outcomes between groups at 2 years after surgery, which satisfied the non-inferiority criterion of Group 1 in terms of clinical scores and knee laxity compared to Group 2.

CONCLUSION

The surgical outcomes of anatomical ACL reconstruction in patients with non-isometric ACL graft were not inferior in terms of clinical scores and knee laxity, compared to those with nearly-isometric ACL graft. The graft tunnel placement in the isometric position during anatomical ACL reconstruction, which is technically challenging in the clinical setting, is not a crucial factor in terms of clinical outcomes.

LEVEL OF EVIDENCE

Level IV.

Non-anatomic tunnel position increases the risk of revision anterior cruciate ligament reconstruction

PURPOSE

Anterior cruciate ligament (ACL) graft failure is a complication that may require revision ACL reconstruction (ACL-R). Non-anatomic placement of the femoral tunnel is thought to be a frequent cause of graft failure; however, there is a lack of evidence to support this belief. The purpose of this study was to determine if non-anatomic femoral tunnel placement is associated with increased risk of revision ACL-R.

METHODS

After screening all 315 consecutive patients who underwent primary single-bundle ACL-R by a single senior orthopedic surgeon between January 2012 and January 2017, 58 patients were found to have both strict lateral radiographs and a minimum of 24 months follow-up without revision. From a group of 456 consecutive revision ACL-R, patients were screened for strictly lateral radiographs and 59 patients were included in the revision group. Femoral tunnel placement for each patient was determined using a strict lateral radiograph taken after the primary ACL-R using the quadrant method. The center of the femoral tunnel was measured in both the posterior-anterior (PA) and proximal-distal (PD) dimensions and represented as a percentage of the total distance (normal center of anatomic footprint: PA 25% and PD 29%).

RESULTS

In the PA dimension, the revision group had significantly more anterior femoral tunnel placement compared with the primary group (38% ± 11% vs. 28% ± 6%, p < 0.01). Among patients who underwent revision; those with non-traumatic chronic failure had statistically significant more anterior femoral tunnel placement than those who experienced traumatic failure (41% ± 13% vs. 35% ± 8%, p < 0.03). In the PD dimension, the revision group had significantly more proximal femoral tunnel placement compared with the primary group (30% ± 9% vs 38% ± 9%, p < 0.01).

CONCLUSION

In this retrospective study of 58 patients with successful primary ACL-R compared with 59 patients with failed ACL-R, anterior and proximal (high) femoral tunnels for ACL-R were shown to be independent risk factors for ACL revision surgery. As revision ACL-R is associated with patient- and economic burden, particular attention should be given to achieving an individualized, anatomic primary ACL-R. Surgeons may reduce the risk of revision ACL-R by placing the center of the femoral tunnel within the anatomic ACL footprint.

LEVEL OF EVIDENCE

Level III.

Failure rate analysis and clinical outcomes of two different femoral tunnel positions using anteromedial portal technique in anterior cruciate ligament reconstruction

AIM

To analyze two different femoral tunnel positions and to evaluate their correlation with clinical, functional outcomes and surgical revision rate in patients who underwent primary arthroscopic anterior cruciate ligament (ACL) reconstruction with anteromedial (AM) portal technique.

METHODS

From January 2015 to October 2018, we recruited 244 patients that underwent primary single-bundle ACL reconstruction, using four strand-semitendinosus graft and AM portal technique for femoral tunnel placement. Patients were divided into two groups based on the different femoral tunnel positions: 117 patients of group A had ACL footprint center femoral tunnel position compared with 127 patients of group B, with femoral tunnel placement close to the AM bundle footprint. Preoperatively and at last follow up, all patients were assessed subjectively by Lysholm, Tegner, and International Knee Documentation Committee (IKDC) scores, while Lachman, Pivot-shift, and KT-1000 tests were performed to evaluate knee joint stability.

RESULTS

Group B patients showed significantly better results in Lysholm, objective, and subjective IKDC scores compared with patients of group A (P < 0.001). A significantly higher surgical failure rate was found in group A than in group B (10.26% vs. 2.3%; P < 0.001). A higher anterior knee laxity was recorded in patients of group A than in patients of group B (1.9 ± 1.1 vs. 1.3 ± 1 mm; P < 0.001); a reduction in mean anterior tibial translation from preoperative to final follow up was found in group B compared with group A (3.5 ± 1.2 vs. 2.7 ± 1.1 mm; P < 0.001). No significant differences in the Tegner scale were found between the two groups.

CONCLUSION

ACL reconstruction performed using the AM portal technique showed better and more satisfactory clinical and functional outcomes associated with a lower failure rate when the femoral tunnel had been placed more eccentrically in the footprint, in the AM bundle center position.

Freehand Anatomic Transtibial Single-Bundle Anterior Cruciate Ligament Reconstruction

Creation of the femoral tunnel for single-bundle anterior cruciate ligament (ACL) reconstruction has a high rate of nonanatomic placement with the transtibial (TT) technique but yields better restoration with the anteromedial portal technique and close restoration of the anatomic femoral footprint with the outside-in technique. Modifications of the traditional (TT) technique have been described to restore the native femoral ACL footprint and to simulate double-bundle reconstruction. Modified TT techniques try to capture the anatomic femoral footprint through an anatomic tibial tunnel. In the technique described in this article, the anatomic femoral footprint is drilled first by the use of a 2.5-mm Kirschner wire through the parapatellar anteromedial portal, making an angle 30° to the sagittal plane and 20° to the horizontal plane. The wire is drilled while the knee is hyperflexed and then withdrawn from outside until its distal end reaches the intercondylar notch. The wire is then advanced in an antegrade manner while the knee is flexed 90° until it reaches the center of the marked tibial footprint. The angle of knee flexion may be slightly increased or decreased around 90° with or without slight internal rotation to capture the anatomic tibial footprint. The procedure is completed as a TT single-bundle ACL reconstruction.

Revision Anterior Cruciate Ligament Reconstruction after Surgical Management of Multiligament Knee Injury

The purpose of this study is to determine factors associated with the need for revision anterior cruciate ligament reconstruction (ACLR) after multiligament knee injury (MLKI) and to report outcomes for patients undergoing revision ACLR after MLKI. This involves a retrospective review of 231 MLKIs in 225 patients treated over a 12-year period, with institutional review board approval. Patients with two or more injured knee ligaments requiring surgical reconstruction, including the ACL, were included for analyses. Overall, 231 knees with MLKIs underwent ACLR, with 10% (n = 24) requiring revision ACLR. There were no significant differences in age, sex, tobacco use, diabetes, or body mass index between cohorts requiring or not requiring revision ACLR. However, patients requiring revision ACLR had significantly longer follow-up duration (55.1 vs. 37.4 months, p = 0.004), more ligament reconstructions/repairs (mean 3.0 vs. 1.7, p < 0.001), more nonligament surgeries (mean 2.2 vs. 0.7, p = 0.002), more total surgeries (mean 5.3 vs. 2.4, p < 0.001), and more graft reconstructions (mean 4.7 vs. 2.7, p < 0.001). Patients in both groups had similar return to work (p = 0.12) and activity (p = 0.91) levels at final follow-up. Patients who had revision ACLR took significantly longer to return to work at their highest level (18 vs. 12 months, p = 0.036), but similar time to return to their highest level of activity (p = 0.33). Range of motion (134 vs. 127 degrees, p = 0.14), pain severity (2.2 vs. 1.7, p = 0.24), and Lysholm's scores (86.3 vs. 90.0, p = 0.24) at final follow-up were similar between groups. Patients requiring revision ACLR in the setting of a MLKI had more overall concurrent surgeries and other ligament reconstructions, but had similar final outcome scores to those who did not require revision surgery. Revision ligament surgery can be associated with increased pain, stiffness, and decrease patient outcomes. Revision surgery is often necessary after multiligament knee reconstructions, but patients requiring ACLR in the setting of a MLKI have good overall outcomes, with patients requiring revision ACLR at a rate of 10%.

Feasibility and accuracy of orthopaedic surgical robot system for intraoperative navigation to locate bone tunnel in anterior cruciate ligament reconstruction

BACKGROUND

The combination of navigational system and robotics has the potential to accurately identify and drill bone tunnels in anterior cruciate ligament (ACL) reconstruction. This study explores the feasibility and accuracy of bone tunnel positioning using the TiRobot, an orthopaedic surgical robot.

METHODS

The experiment was divided into two groups. In group A, the bone tunnels were positioned using the TiRobot surgical robot (n = 8). In group B, handheld locators were used for positioning (n = 8).

RESULTS

TiRobot can be used for positioning the ACL bone tunnel. The accuracy of positioning the femoral tunnel in group A and B was 1.00 ± 0.20 and 3.10 ± 0.59 mm, respectively (t = -9.49, P < 0.001). As for tibial tunnel, the accuracy was 1.02 ± 0.20 and 2.64 ± 0.14 mm, respectively (t = -18.54, P < 0.001).

CONCLUSIONS

The bone tunnel drilling precision using TiRobot for ACL reconstruction surgery was more accurate than traditional surgical techniques.

Clinical Outcomes of Anterolateral Ligament Reconstruction or Lateral Extra-articular Tenodesis Combined With Primary ACL Reconstruction: A Systematic Review With Meta-analysis

BACKGROUND

Residual rotational instability after isolated anterior cruciate ligament reconstruction (ACLR) has been a challenge for many years. Anterolateral extra-articular procedures (AEAPs), including anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET), are performed as a surgical option for additional rotational stability, but clear evidence for their usefulness is lacking.

PURPOSE

To conduct a systematic review and meta-analysis of the literature regarding the efficacy of AEAP in primary ACLR.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

A literature search, data extraction, and quality assessment were conducted by 2 independent reviewers. MEDLINE, EMBASE, and the Cochrane Library were searched in April 2020, following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A total of 3444 studies were screened, and 20 studies (11 randomized controlled trials and 9 nonrandomized studies) were evaluated. Functional outcomes, stability, and complications were compared between patients who underwent primary ACLR with AEAP and those who underwent isolated primary ACLR. For subgroup analysis, outcomes were compared according to AEAP technique (ALLR vs LET) and time from injury to surgery (≤12 vs >12 months). The methodological quality of the included studies was assessed using the Cochrane risk-of-bias tool, Jadad scale, and Newcastle-Ottawa Scale.

RESULTS

Compared with isolated ACLR, combined ACLR with AEAP led to improved pivot-shift grades and graft failure rates, regardless of the AEAP technique or of time from injury to surgery. A limited, marginal improvement in subjective function score was observed in patients who underwent AEAP combined with ACLR. In contrast to ALLR, patients who underwent LET combined with ACLR had an increased risk of knee stiffness and adverse events.

CONCLUSION

Our review suggests that when there is a need to improve rotational stability and subjective function, AEAP combined with primary ACLR can be considered regardless of time from injury. ALLR appeared to be a better option for improving rotational stability compared with LET.

Sagittal Inclination Angle of Graft Is Associated With Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To evaluate whether the sagittal inclination angle (SIA) of a graft is associated with postoperative knee stability after anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

All patients who had undergone anatomic ACL reconstruction between April 2014 and September 2015 in addition to volunteers with no history of knee injury were eligible for inclusion in this study. The patients were evaluated by magnetic resonance imaging of the knee in full extension at 1 year after surgery, as were volunteers. The posterior tibial slope (PTS) angle and the SIA of the intact ACL and reconstructed graft were measured relative to each medial and lateral tibial plateau. The patients were examined for knee stability by the side-to-side difference in the anterior tibial translation on stress radiographs at minimum 2-year follow-up.

RESULTS

We included 43 patients (26 male, 17 female, mean age 32.8 ± 14.8 years) and 12 volunteers (7 male, 5 female, mean age 28.7 ± 3.1 years) as normal controls. The mean follow-up duration was 29.8 ± 3.6 months. The mean PTS angle and mean SIA in the patients did not significantly differ from those of the intact ACL. The PTS angle in the patients was not significantly correlated with postoperative side-to-side difference in the anterior tibial translation. However, the graft SIA was significantly correlated with the postoperative anterior tibial translation (medial SIA; r = 0.42, P = .005, lateral SIA; r = 0.52, P < .001).

CONCLUSIONS

Even if anatomically reconstructed, the graft SIA in reference to the tibial plateau at full knee extension is variable and is associated with postoperative knee stability. The larger graft SIA was correlated with graft laxity after anatomic ACL reconstruction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Clinical and Radiological Outcomes of Anteromedial Portal Versus Transtibial Technique in ACL Reconstruction: A Systematic Review

Background:

The drilling technique used to make a femoral tunnel is critically important for determining outcomes after anterior cruciate ligament (ACL) reconstruction. The 2 most common methods are the transtibial (TT) and anteromedial (AM) techniques.

Purpose:

To determine whether graft orientation and placement affect clinical outcomes by comparing clinical and radiological outcomes after single-bundle ACL reconstruction with the AM versus TT technique.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Articles in PubMed, EMBASE, the Cochrane Library, ISI Web of Science, Scopus, and MEDLINE were searched from inception until April 25, 2020, using the following Boolean operators: transtibial OR trans-tibial AND (anteromedial OR trans-portal OR independent OR three portal OR accessory portal) AND anterior cruciate ligament.

Results:

Of 1270 studies retrieved, 39 studies involving 11,207 patients were included. Of these studies, 14 were clinical, 13 were radiological, and 12 were mixed. Results suggested that compared with the TT technique, the AM technique led to significantly improved anteroposterior and rotational knee stability, International Knee Documentation Committee (IKDC) scores, and recovery time from surgery. A higher proportion of negative Lachman (P = .0005) and pivot-shift test (P = .0001) results, lower KT-1000 arthrometer maximum manual displacement (P = .00001), higher Lysholm score (P = .001), a higher incidence of IKDC grade A/B (P = .05), and better visual analog scale score for satisfaction (P = .00001) were observed with the AM technique compared with the TT technique. The AM drilling technique demonstrated a significantly shorter tunnel length (P = .00001). Significant differences were seen between the femoral and tibial graft angles in both techniques. Low overall complication and revision rates were observed for ACL reconstruction with the AM drilling technique, similar to the TT drilling technique.

Conclusion:

In single-bundle ACL reconstruction, the AM drilling technique was superior to the TT drilling technique based on physical examination, scoring systems, and radiographic results. The AM portal technique provided a more reproducible anatomic graft placement compared with the TT technique.

Clinical Outcome Evaluation of Anatomic Anterior Cruciate Ligament Reconstruction With Tunnel Positioning Using Gold Standard Techniques: A Systematic Review and Meta-analysis

Background:

There have been conflicting results about the theoretical advantages of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

Purpose:

To evaluate the clinical and functional outcomes comparing anatomic single- versus double-bundle techniques, anatomic versus nonanatomic techniques, and transportal versus outside-in tunnel drilling for ACL reconstruction.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

A search was performed in the MEDLINE and EMBASE databases up to August 2018 for clinical trials comparing anatomic ACL reconstruction (with tunnel positioning demonstrated using gold standard radiologic techniques) with another technique, with a minimum functional and biomechanical follow-up of 6 months. A meta-analysis was performed to compare clinical and functional outcomes between anatomic single- versus double-bundle reconstruction and between anatomic versus nonanatomic techniques, using the risk difference or the mean difference. Risk of bias of the included studies was assessed using the Newcastle-Ottawa Scale for cohort and case-control studies and the Cochrane Risk of Bias tool and Jadad Score for randomized controlled trials.

Results:

Included were 15 studies comprising 1290 patients (follow-up, 12-36 months). No significant differences favoring anatomic double-bundle over anatomic single-bundle reconstruction or outside-in over transportal techniques were found. The meta-analyses showed significant differences in the International Knee Documentation Committee (IKDC) objective score (risk difference, –0.14; 95% confidence interval, –0.27 to –0.01) favoring anatomic over nonanatomic reconstruction. No statistically significant differences were found between anatomic and nonanatomic surgical techniques on other functional scores or clinical examination outcomes, including the IKDC subjective score, Lysholm score, Tegner score, KT-1000 arthrometer test, or pivot-shift test.

Conclusion:

Double-bundle reconstruction was not superior to the single-bundle technique in clinical and functional outcomes. Anatomic ACL reconstruction shows significantly superior results over nonanatomic ACL reconstruction, reinforcing the anatomic technique as the gold standard choice for clinical practice.

Establishment of near and non isometric anterior cruciate ligament reconstruction with artificial ligament in a rabbit model

Background

Tunnel position deicide the isometry of graft attachment in synthetic anterior cruciate ligament (ACL) reconstruction. Near-isometric tunnel position may have advantage in graft integration and knee function in ACL reconstruction (ACLR) with polyethylene terephthalate (PET) ligament. Few studies focused on tunnel position isometry when conduct ACLR with an animal model. This study aimed to establish a preclinical rabbit model of near and non isometric ACLR with PET ligament and investigate the advantage of near-isometric ACLR compared to non-isometric ACLR.

Methods

Nine hind limbs of rabbit were used in tunnel position study. Two femoral(anatomic, nonanatomic) tunnels and three tibial(anterior, middle, posterior) tunnels were used to measure tunnel position isometry during knee full range of motion. The tunnel position combination with minimal isometry was considered as near-isometric tunnel position. Then, 48 rabbits divided into two groups were conducted near or non isometric ACLR with PET ligament with graft fixation angle of 30° and constant tension of 5N. PET ligament isometry, range of motion(ROM) restriction, knee laxity were recorded after operation and followed up with macroscopic observation, microcomputed tomography (micro-CT) analysis, histology assessment and biomechanical test at 4 and 8 weeks postoperatively.

Results

The tunnel combination with minimal isometry was femoral anatomic position and tibial posterior position(5.19 ​± ​1.78%) and considered as near-isometric tunnel position. ROM restriction were observed in non-isometric group (22.50 ​± ​14.14°) while none in near-isometric group. However, no ROM restriction observed at 8 weeks in both group. Knee laxity compared to contralateral knee were better in near-isometric group than non-isometric group (stable/slack/total 10/2/12 VS 3/9/12, p ​= ​0.012) at 8 weeks postoperatively. Supeiror PET ligament integration were also observed in near-isometric group through macroscopic observation, micro-CT analysis, histology assessment at both 4 and 8 weeks. The failure load in the Near-Isometric group at 8 weeks were higher than timezero reconstruction with statistical difference (156.8N ​± ​25.98N vs.102.6 ​± ​22.96N, p ​= ​0.02).

Conclusion

A rabbit model of ACLR based on tunnel position isometry was successfully established in this study. The near-isometric tunnel position in rabbit model was femoral anatomic position and tibial posterior position. A near-isometric ACLR with PET ligament did not cause ROM restriction and had a better graft integration and follow-up stability than non-isometric ACLR with ROM restriction.

The Translational Potential of this Article

The study demonstrate the establishmentof near-isometric tunnel position and non-isometric tunnel position with significant difference of ROM restriction and graft-bone integration. The described tunnel positions with differential isometry in a rabbit ACLR provides a reproducible and translational small animal model and enables preclinical research between tunnel position isometry and its affection on variable grafts, graft integration and knee function.

No differences in clinical outcomes and graft healing between anteromedial and central femoral tunnel placement after single bundle ACL reconstruction

PURPOSE

The purpose of this study was to compare clinical outcomes and graft healing after anterior cruciate ligament (ACL) reconstruction with anteromedial and central femoral tunnel placement.

METHODS

During 2016 and 2018, 110 consecutive patients underwent single bundle ACL reconstruction; 85 patients met the inclusion criteria, and each patient underwent 3D-CT within 1 week and MRI 1.5 years after the operation. The central point of the femoral tunnel and signal/noise quotient (SNQ) of three regions of interest (ROI) in the intra-articular graft were measured to analyse the tunnel position and graft healing extent. Clinical assessments, including functional scores, KT-2000 arthrometer measurements and pivot-shift tests, were evaluated at the 2-year follow-up. Patients were divided into two groups depending on the femoral tunnel position: the anteromedial position group (Group A) and the centre position group (Group B).

RESULTS

Seventy-one patients were available for the 2-year follow-up and MRI examination: 34 patients in Group A and 35 patients in Group B, and 2 patients were excluded for an eccentric tunnel position. No graft failure occurred, and compared with the preoperative assessment outcomes, the outcomes of both groups improved at the final follow-up. Group A was significantly better than Group B regarding the KT-2000 arthrometer measurements (P = 0.031). No significant differences were observed in terms of functional scores, pivot-shift test results, or the SNQ between groups.

CONCLUSIONS

No differences in clinical outcomes or graft healing were found between AM and central femoral tunnel placements in single bundle ACL reconstruction. Therefore, satisfactory clinical outcomes, knee stability and graft healing can be obtained for both femoral tunnel placements.

LEVEL OF EVIDENCE

II.

Superior Postoperative Stability and Functional Outcomes With Anteromedial Versus Transtibial Technique of Single-Bundle Autologous Hamstring Anterior Cruciate Ligament Reconstruction: A Meta-analysis of Prospective Randomized Controlled Trials

PURPOSE

The aim of this meta-analysis was to compare the postoperative stability and functional outcomes of anteromedial (AM)- and transtibial (TT)-based single-bundle hamstring anterior cruciate ligament (ACL) reconstruction techniques.

METHODS

A meta-analysis comparing the outcomes of single-bundle hamstring ACL reconstruction using the AM and TT techniques was performed. Prospective randomized controlled trials identified from searches of PubMed, Cochrane, and Embase were included in this review. The outcome measures analyzed included postoperative Lachman test and pivot-shift test results, side-to-side difference, International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity score.

RESULTS

A total of 7 randomized controlled trials (654 patients) were included in this review. The AM technique, compared with the TT technique, resulted in superior postoperative stability based on the negative Lachman test rate (risk ratio [RR], 1.12; 95% confidence interval [CI], 1.01 to 1.24; P = .03; 95% prediction interval [PI], 0.32 to 3.46), negative pivot-shift test rate (RR, 1.16; 95% CI, 1.06 to 1.28; P = .002; 95% PI, 0.40 to 2.88), and side-to-side difference (weighted mean difference [WMD], -0.32 mm; 95% CI, -0.48 to -0.16; P < .0001; 95% PI, -0.55 to -0.09). Likewise, the AM technique contributed to superior postoperative functional outcomes based on the proportion of IKDC grade A findings (RR, 1.16; 95% CI, 1.02 to 1.32; P = .03; 95% PI, 0.40 to 2.83) and the Lysholm score (WMD, 0.82; 95% CI, 0.23 to 1.41; P = .007; 95% PI, -0.22 to 1.86). However, the AM and TT techniques had comparable subjective IKDC scores (WMD, 0.98; 95% CI, -0.91 to 2.88; P = .31; 95% PI, -3.18 to 5.14) and Tegner activity scores (WMD, 0.32; 95% CI, -0.23 to 0.86; P = .25; 95% PI, -3.84 to 4.48).

CONCLUSIONS

The AM method of single-bundle hamstring ACL reconstruction results in superior postoperative stability and functional outcomes compared with the TT method.

LEVEL OF EVIDENCE

Level I, systematic review of Level I studies.

Editorial Commentary: Remember the Risk Factors During Individualized, Anatomic, Value-Based Anterior Cruciate Ligament Reconstruction

Understanding the etiology behind anterior cruciate ligament (ACL) reconstruction failure is a complex topic still being investigated heavily. The 3 classes of failure are technical, traumatic, and biologic. Technical errors are most common and most frequently reflect tunnel malposition. In addition, tibial slope has long been understood to be a risk factor for failed ACL reconstruction. Although not routinely performed at time of primary ACL reconstruction, osteotomy may be considered in the setting of failed ACL reconstruction. Relative quadriceps weakness is a risk factor, and we recommend sport-specific return-to-play testing as well as benchmarks for relative quadriceps strength before full return to activity. Revision ACL reconstruction is associated with both increased costs and worse patient outcomes, so every effort should be made to give patients the best chance of success after the index surgery. Whereas this begins with understanding the patient's history and risk factors for failure, it crescendos with careful attention to the individually variable factors that make each case unique, tailoring one's management to ensure that each patient receives an anatomic, individualized, and value-based ACL reconstruction.

Anterior Cruciate Ligament Graft Tunnel Placement and Graft Angle Are Primary Determinants of Internal Knee Mechanics After Reconstructive Surgery

BACKGROUND

Graft placement is a modifiable and often discussed surgical factor in anterior cruciate ligament (ACL) reconstruction (ACLR). However, the sensitivity of functional knee mechanics to variability in graft placement is not well understood.

PURPOSE

To (1) investigate the relationship of ACL graft tunnel location and graft angle with tibiofemoral kinematics in patients with ACLR, (2) compare experimentally measured relationships with those observed with a computational model to assess the predictive capabilities of the model, and (3) use the computational model to determine the effect of varying ACL graft tunnel placement on tibiofemoral joint mechanics during walking.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen participants who had undergone ACLR were tested. Bilateral ACL footprint location and graft angle were assessed using magnetic resonance imaging (MRI). Bilateral knee laxity was assessed at the completion of rehabilitation. Dynamic MRI was used to measure tibiofemoral kinematics and cartilage contact during active knee flexion-extension. Additionally, a total of 500 virtual ACLR models were created from a nominal computational knee model by varying ACL footprint locations, graft stiffness, and initial tension. Laxity tests, active knee extension, and walking were simulated with each virtual ACLR model. Linear regressions were performed between internal knee mechanics and ACL graft tunnel locations and angles for the patients with ACLR and the virtual ACLR models.

RESULTS

Static and dynamic MRI revealed that a more vertical graft in the sagittal plane was significantly related (P < .05) to a greater laxity compliance index (R² = 0.40) and greater anterior tibial translation and internal tibial rotation during active knee extension (R² = 0.22 and 0.23, respectively). Similarly, knee extension simulations with the virtual ACLR models revealed that a more vertical graft led to greater laxity compliance index, anterior translation, and internal rotation (R² = 0.56, 0.26, and 0.13). These effects extended to simulations of walking, with a more vertical ACL graft inducing greater anterior tibial translation, ACL loading, and posterior migration of contact on the tibial plateaus.

CONCLUSION

This study provides clinical evidence from patients who underwent ACLR and from complementary modeling that functional postoperative knee mechanics are sensitive to graft tunnel locations and graft angle. Of the factors studied, the sagittal angle of the ACL was particularly influential on knee mechanics.

CLINICAL RELEVANCE

Early-onset osteoarthritis from altered cartilage loading after ACLR is common. This study shows that postoperative cartilage loading is sensitive to graft angle. Therefore, variability in graft tunnel placement resulting in small deviations from the anatomic ACL angle might contribute to the elevated risk of osteoarthritis after ACLR.

Positioning of the Tibial Tunnel After Single-Bundle ACL Primary Reconstruction on 3D CT scans: A New Method

Purpose

To assess intra-articular tunnel aperture positioning after primary anterior cruciate ligament (ACL) reconstruction with either the reference standard method or the intercondylar area method in a single center using 3-dimensional (3D) computed tomography (CT) scans and to evaluate the intra-articular position of the tibial tunnel relative to the ACL footprint.

Methods

3D CT scans were performed after 120 single-bundle primary ACL reconstruction cases. The center of the tibial tunnel aperture and the center of the ACL footprint were referenced on axial views of the tibial plateau in the anteroposterior (AP) and mediolateral (ML) planes according to a centimetric grid system including the whole plateau (reference standard). This was compared with a grid system based on intercondylar area bony anatomy. The posterior aspect of intertubercular fossa, anterior aspect of the tibial plateau, medial intercondylar ridge, and crossing point between lateral intercondylar ridge and posterior margin were used as landmarks to define the grid.

Results

According to the reference standard method, the center of the tibial tunnel aperture was positioned 0.57 ± 2.62 mm more posterior and 0.67 ± 1.55 mm more medial than the center of the footprint. According to the intercondylar area method, the center of the tibial tunnel aperture was positioned 1.32 ± 2.74 mm more posterior and 0.66 ± 1.56 mm more medial than the center of the footprint. The position difference between the center of the tunnel aperture and the center of the footprint were statistically correlated for both grids, with r = –0.887, P < .001 for AP positioning and r = 0.615, P < .001 for ML positioning.

Conclusion

This intercondylar area method using arthroscopic landmarks can be used to assess tunnel placement on 3D CT scans after ACL reconstruction.

Level of Evidence

III, retrospective comparative study.

Clinical and Radiographic Outcomes of Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Graft and Femoral Cortical Button Fixation at Minimum 20-Year Follow-up

BACKGROUND

The short-term outcomes of anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone or hamstring tendon (HT) graft are excellent with good clinical stability and patient-reported outcomes. Although some studies have reported the long-term outcomes of bone-patellar tendon-bone graft ACL reconstruction, few have reported the outcomes of HT graft ACL reconstruction.

PURPOSE

To assess clinical and radiographic outcomes of HT graft ACL reconstruction with femoral cortical button fixation at a minimum 20-year follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A prospective study was performed in which all patients undergoing isolated transtibial primary ACL reconstruction between 1994 and 1996 with HT graft and femoral cortical button fixation were assessed clinically and radiographically. Follow-up was obtained in 48 of 94 patients (51%). Median (interquartile range) age at operation was 31 years (26-39 years); median follow-up was 21 years (20-22 years); 65% were male; and 48% had meniscal injury at surgery and underwent partial meniscectomy. Graft rupture, reoperation, and contralateral injury rates were assessed; clinical stability was measured using the KT-1000 arthrometer; patient-reported outcomes were assessed (International Knee Documentation Committee [IKDC], Lysholm, Forgotten Joint Score, Tegner activity, Knee injury and Osteoarthritis Outcome Score [KOOS], Anterior Cruciate Ligament Quality of Life [ACL-QOL], EuroQol 5-Dimension 5-Level [EQ-5D-5L]); and radiographic osteoarthritis (defined as Kellgren-Lawrence grade ≥2) was assessed for the ipsilateral and the contralateral knee.

RESULTS

Graft rupture occurred in 4 patients (8%), contralateral injury in 4 patients (8%), and reoperation in 15 patients (31%), which consisted mainly of meniscal tears or hardware removal. In patients with an intact graft, excellent patient-reported outcome measures (PROMs) were noted, with a median Lysholm of 90 (78-100), subjective IKDC of 86 (72-95), and KOOS-Sports of 86 (58-100). There was low awareness of the operated knee (Forgotten Joint Score, 81 [60-96]) and good quality of life (ACL-QOL, 85 [75-94]; EQ-5D-5L, 0.87 [0.83-1.00]). Median side-to-side difference, as measured with the KT-1000 arthrometer, was 1 mm (-1 to 3 mm). Radiographic osteoarthritis was evident in 49% of ipsilateral and 10% of contralateral knees and was associated with meniscectomy at index surgery and decreased PROMs at follow-up.

CONCLUSION

Long-term outcomes of transtibial HT graft ACL reconstruction with femoral cortical button fixation are generally good with a low failure rate, low awareness of the operated knee, and good clinical stability. Radiographic osteoarthritis was evident in approximately half of the patients at 20-year follow-up and was associated with meniscectomy at index surgery and decreased PROMs at follow-up.

Clinical Outcome of Remnant-Preserving and I.D.E.A.L. Femoral Tunnel Technique for Anterior Cruciate Ligament Reconstruction

Objective

To assess the clinical results of the remnant‐preserving and I.D.E.A.L. femoral tunnel technique in the arthroscopic treatment of anterior cruciate ligament (ACL) injuries.

Methods

This was a retrospective single‐center, single‐surgeon study reviewing data from November 2016 to March 2019. Based on our inclusion/exclusion criteria, a total of 31 patients (18 males, 13 females; mean age, 23.6 years) who underwent arthroscopic ACL reconstruction with the remnant preservation and I.D.E.A.L. femoral tunnel technique were recruited and had a minimum follow‐up of 12 months. Clinical data and status of knee stability were recorded. The International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity scale were collected both preoperatively and at a minimum of 1‐year follow‐up.

Results

Statistically significant differences were detected between the preoperative and postoperative values for Lachman test and pivot‐shift test (P < 0.01). The mean postoperative Lysholm score was 89.6 ± 9.4, whereas the mean preoperative Lysholm score was 47.3 ± 12.8 (P < 0.01). The mean Tegner activity score was significantly higher at postoperative evaluation than at preoperative evaluation (6.5 ± 2.1 vs 2.6 ± 1.8; P < 0.01). The mean IKDC score was significantly improved from 49.5 ± 10.6 preoperatively to 88.2 ± 10.7 postoperatively (P < 0.01). No case of infection was reported. No radiograph showed any joint space narrowing or degenerative change at the last postsurgical follow‐up.

Conclusion

The anatomical remnant‐preserving and I.D.E.A.L. femoral tunnel technique achieves a satisfactory clinical outcome and provides an effective option for the treatment of ACL injuries.

Can Surgeons Identify ACL Femoral Ridges Landmark and Optimal Tunnel Position? A 3D Model Study

Purpose

To examine the ability of surgeons to identify the osseous landmarks associated with the femoral anterior cruciate ligament (ACL) footprint and locate optimal tunnel placement on 3-dimensional (3D) printed models compared with intraoperative placement.

Methods

Twelve sports fellowship-trained orthopaedic surgeons were asked to identify a femoral landmark and an ACL footprint on 10 different 3D printed knees. The 3D models were made based on 20 real patients with different anatomical morphology who later received ACL reconstructive surgery using independent drilling. ImageJ software was used to quantify the measurements, which were then analyzed using descriptive statistics.

Results

Overall, none of the surgeons were able to consistently identify the junction of the bony ridges. The mean error per participant ranged from 2.81 to 7.34 mm in the proximal direction (P = 3.30e-05) and from 2.42 to 8.05 mm in the posterior direction (P =4.88e-12). None of the surgeons were able to appropriately identify the center of the femoral footprint on the anatomic 3D models. The difference between the center of the footprint surgeons identified on the 3D model and the tunnel graft location in surgery was significantly different (P = .0046). On average, the magnitude of the error when the surgeons performed the actual surgery was 3.72 ± 2.43 mm, whereas on the 3D models it was 5.82 ± 1.97 mm.

Conclusions

Experienced sports fellowship-trained orthopaedic surgeons were unable to correctly identify the junction of the intercondylar and bifurcate ridges and the native ACL footprint on 3D models. Operatively placed tunnels were more accurate implying that looking either through a scope or soft-tissue landmarks play a significant role in surgeons ACL footprint localization.

Clinical Relevance

The graft position for ACL reconstruction plays an important role on the kinematics of the knee. This paper shows that soft tissue landmarks are needed to provide reliable reference points for reconstruction.

Central patellar portal placement frequently provokes anterior knee compartment radiological abnormalities in anterior cruciate ligament reconstruction

PURPOSE

A central patellar (CP) portal can be used to view the native femoral insertion site of the anterior cruciate ligament (ACL). It aids in the drilling of an anatomical tunnel; however, its impact on the patellar tendon and the infrapatellar fat pad remains a concern. The aim of this study was to investigate complications associated with the CP portal use in arthroscopic ACL reconstruction (ACLR).

METHODS

A total of 105 patients (107 knees, 60 females) who underwent ACLR with a CP portal from 2012 to 2017 were included in this study. The mean age was 28.3 ± 12.4 years. All surgeries were single-bundle reconstructions using the trans-tibial technique via the CP and anteromedial portals. Post-operative events, magnetic resonance imaging (MRI), and arthroscopic findings associated with CP portal creation were evaluated.

RESULTS

Five patients (4.7%) had symptomatic postoperative complications, which included two patients with patellar tendonitis and three patients with fibrosis in the anterior knee compartment. Abnormal signal intensity of the patellar tendon on MRI and increased thickness at the CP portal area were found in 18 of 25 knees (72%). Three of 56 knees (5.4%) that underwent second-look arthroscopy showed fibrosis of the infrapatellar fat pad. Seven patients (12.5%) showed hypertrophy of the ligamentum mucosum.

CONCLUSIONS

The rate of symptomatic complications associated with CP portal placement was 4.7%; however, abnormal MRI or follow-up arthroscopy findings were much higher than clinically symptomatic patients. This study suggests that CP portal placement could provoke anterior knee compartment fibrosis or hypertrophy.

LEVEL OF EVIDENCE

IV.

Inclination of Blumensaat's line influences on the accuracy of the quadrant method in evaluation for anterior cruciate ligament reconstruction

PURPOSE

The quadrant method is used to evaluate the bone tunnel position with the grid based on the Blumensaat's line in anterior cruciate ligament (ACL) reconstruction. This study aimed to clarify the influence of variation in the Blumensaat's line on the accuracy of the quadrant method measurements.

METHODS

A retrospective review of the radiological records of patients aged 18-30 years who underwent computed tomography (CT) scanning of the knee joint was conducted. The Blumensaat's line inclination angle (BIA), along with the most posterior point of the posterior condyle (point P) position using the quadrant method and morphology of the Blumensaat's line were measured on true lateral transparent three-dimensional CT images of the distal femoral condyle in 147 patients. Statistical analysis was conducted to determine associations among these measurements.

RESULTS

BIA was 37.5° (standard deviation 4.2°; range 27°-48°). The point P position was significantly correlated with BIA in the high/low (R² = 0.590, P < 0.0001) and deep/shallow (R² = 0.461, P < 0.0001) directions. The morphology of the Blumensaat's line was straight in 35 knees (23.8%); whereas, the remaining 112 knees (76.2%) were not straight but had some hill on the Blumensaat's line. No significant difference among the morphological variation of the Blumensaat's line was observed in BIA and the point P position.

CONCLUSION

There was a strong correlation between BIA and the point P measured using the quadrant method, suggesting the influence of the Blumensaat's line on the accuracy of the quadrant method measurements in ACL reconstruction. As for the clinical relevance, surgeons should be careful in application of the quadrant method for ACL reconstruction, because the variation of the Blumensaat's line inclination influences the accuracy of this method.

Intraoperative fluoroscopy shows better agreement and interchangeability in tibial tunnel location during single bundle anterior cruciate ligament reconstruction with postoperative three-dimensional computed tomography compared with an intraoperative image-free navigation system

BACKGROUND

Fluoroscopy and navigation systems provide an accurate and reproducible method of guiding anatomical tunnel positioning during anterior cruciate ligament reconstruction (ACLR). The aim was to evaluate the differences in tibial tunnel location assessed by both an intraoperative navigation system and fluoroscopy, validated using a one-week postoperative three-dimensional computed tomography (3DCT).

METHODS

The tibial tunnel location in a consecutive series of 35 patients who received a single-bundle ACLR was evaluated by intraoperative navigation system, fluoroscopic image and compared with postoperative 3DCT position. The location to the anterior-posterior (AP) and medial-lateral (ML) direction were compared between all three methods.

RESULTS

The tibial tunnel locations were 46.7 ± 4.5%, 44.5 ± 1.9%, and 43.6 ± 2.4% in ML direction, and 42.8 ± 7.6%, 37.9 ± 3.8%, and 37.9 ± 3.7% in AP direction using an intraoperative navigation system, fluoroscopic image and postoperative 3DCT, respectively. Significant differences between the navigation system and fluoroscopic image (ML, P = 0.001; AP, P = 0.006), and the navigation system and 3DCT (ML, P = 0.001; AP, P < 0.001) were seen. However, there was no significant difference between fluoroscopy and 3DCT (ML, P = 0.315; AP, P = 0.999). There was a significant lack of agreement for analyses measured using a navigation system and 3DCT. Fluoroscopy and 3DCT demonstrated an acceptable agreement (ML, r_pt = -0.21, P = 0.232; AP, r_pt = 0.04, P = 0.826).

CONCLUSIONS

A tibial tunnel location assessed by intraoperative fluoroscopy shows better agreement and interchangeability with one-week postoperative 3DCT validation during single-bundle ACLR compared with an intraoperative image-free navigation system.

Femoral Tunnel Placement Analysis in ACL Reconstruction Through Use of a Novel 3-Dimensional Reference With Biplanar Stereoradiographic Imaging

Background:

The femoral-sided anatomic footprint of the anterior cruciate ligament (ACL) has been widely studied during the past decades. Nonanatomic placement is an important cause of ACL reconstruction (ACLR) failure.

Purpose:

To describe femoral tunnel placement in ACLR through use of a comprehensive 3-dimensional (3D) cylindrical coordinate system combining both the traditional clockface technique and the quadrant method. Our objective was to validate this technique and evaluate its reproducibility.

Study Design:

Descriptive laboratory study.

Methods:

The EOS Imaging System was used to make 3D models of the knee for 37 patients who had undergone ACLR. We designed an automated cylindrical reference software program individualized to the distal femoral morphology of each patient. Cylinder parameters were collected from 2 observers’ series of 3D models. Each independent observer also manually measured the corresponding parameters using a lateral view of the 3D contours and a 2-dimensional stereoradiographic image for the corresponding patient.

Results:

The average cylinder produced from the first observer’s EOS 3D models had a 30.0° orientation (95% CI, 28.4°-31.5°), 40.4 mm length (95% CI, 39.3-41.4 mm), and 19.3 mm diameter (95% CI, 18.6-20.0 mm). For the second observer, these measurements were 29.7° (95% CI, 28.1°-31.3°), 40.7 mm (95% CI, 39.7-41.8 mm), and 19.7 mm (95% CI, 18.8-20.6 mm), respectively. Our method showed moderate intertest intraclass correlation among all 3 measuring techniques for both length (r = 0.68) and diameter (r = 0.63) but poor correlation for orientation (r = 0.44). In terms of interobserver reproducibility of the automated EOS 3D method, similar results were obtained: moderate to excellent correlations for length (r = 0.95; P < .001) and diameter (r = 0.66; P < .001) but poor correlation for orientation (r = 0.29; P < .08). With this reference system, we were able to describe the placement of each individual femoral tunnel aperture, averaging a difference of less than 10 mm from the historical anatomic description by Bernard et al.

Conclusion:

This novel 3D cylindrical coordinate system using biplanar, stereoradiographic, low-irradiation imaging showed a precision comparable with standard manual measurements for ACLR femoral tunnel placement. Our results also suggest that automated cylinders issued from EOS 3D models show adequate accuracy and reproducibility.

Clinical Relevance:

This technique will open multiple possibilities in ACLR femoral tunnel placement in terms of preoperative planning, postoperative feedback, and even intraoperative guidance with augmented reality.

Anterior Cruciate Ligament Femoral Tunnel Placement: An Analysis of the Intended Versus Achieved Position for 221 International High-Volume ACL Surgeons

BACKGROUND

Femoral tunnels that are not anatomically placed within the native anterior cruciate ligament (ACL) footprint during ACL reconstruction are associated with residual instability, graft rupture, and poor clinical outcomes. Although surgeons may intend to place their femoral tunnels within the native ACL attachment, this is not always achieved. This study assesses the variation between intended and achieved femoral tunnel positions in a large cohort of experienced ACL surgeons.

HYPOTHESIS

The accuracy with which experienced ACL surgeons achieve their intended femoral tunnel position is dependent on viewing portal, localization strategy, and drilling technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 221 surgeons indicated their intended femoral tunnel location on a true lateral radiograph of a cadaveric knee specimen and a scaled photograph. Each surgeon then arthroscopically demonstrated the femoral tunnel on the specimen. The position was captured using fluoroscopy. The Euclidean distance (the straight-line distance between 2 points) between the intended and achieved tunnel positions, referenced to a grid applied to the lateral femoral condyle, was compared. Data were analyzed according to surgeons' viewing portal (anteromedial [AM] or anterolateral [AL]), tunnel localization strategy (offset aimer, estimation from landmarks, ACL ruler, or C-arm fluoroscopy), and stated drilling technique (transtibial, AM portal, or outside-in).

RESULTS

Surgeons who viewed the lateral intercondylar notch wall through the AM portal were closer (mean distance, 9.5) to their intended position than those who viewed through the AL portal (mean distance, 15.1; P < .0001). By localization strategy, the mean distance between achieved and intended tunnel positions was greater for surgeons who used an offset aimer (14.5) and estimated the femoral tunnel position (12.9) than for those using a malleable ACL ruler (8.1; P < .0001) and fluoroscopy (4.3; P < .0001). Surgeons' preferred drilling technique (AM portal, transtibial, or outside-in) had no effect on distance between intended and achieved positions. However, the mean achieved position was higher in the intercondylar notch for those using transtibial drilling (P < .042).

CONCLUSION

Surgeons using the AM portal to view the femoral attachment site were closer to their intended tunnel position than those who viewed it with the arthroscope in the AL portal. Surgeons who used fluoroscopy to localize femoral tunnel position were the closest to their intended position. Those who used estimation or an offset aimer had the farthest distance between achieved and intended tunnel positions.

CLINICAL RELEVANCE

Although accurate tunnel placement can be achieved using any method, given the disparity between intended and achieved tunnel positions, it may be advisable, even for high-volume surgeons, to verify the placement of their tunnels using either fluoroscopy or a malleable ACL ruler to ensure that they achieve their intended position. Fluoroscopy may be particularly useful for cases where the native femoral stump is no longer visible and for revisions. Viewing through the AM portal is recommended to aid accuracy of tunnel placement.

A novel approach for optimal graft positioning and tensioning in anterior cruciate ligament reconstructive surgery based on the finite element modeling technique

BACKGROUND

In ACL-reconstructed patients the postoperative knee biomechanics may differ from the intact knee biomechanical behavior which can alter knee kinematics and kinetics, and as a result lead to the progression of knee osteoarthritis. The aim of this study was to demonstrate the potential of finite element models to define the optimal choices in surgical parameters in terms of optimal graft positioning in combination with graft type in order to restore the kinematic and kinetic behavior of the knee as best as possible.

METHODS

A workflow was proposed based on cadaveric experiments in order to restore the injured knee to a near normal physiological condition. Femoral and tibial graft insertion sites and graft fixation tension were optimized to obtain similar intact knee laxity, for three common single-bundle and one double-bundle reconstructions. To verify the success of the surgery with the variables calculated using the proposed workflow, a full walking cycle was simulated with the intact, ACL-ruptured, optimal ACL-reconstructed and non-optimal reconstructed knees.

RESULTS

Our results suggested that for patellar tendon and hamstring tendon grafts, anatomical positioning (fixation force: 40 N), and for quadriceps tendon graft, isometric positioning (fixation tension: 85 N) could recover the intact joint kinematics and kinetics. Also for double-bundle reconstruction, with the numerically calculated optimal insertion sites, both bundles needed 50-N fixation force.

CONCLUSIONS

With optimal graft positioning parameters, following the proposed workflow in this study, any of the single-bundle graft types and surgical techniques (single vs. double-bundle) may be used to acceptably recover the intact knee joint biomechanical behavior.

Knee Extension Deficit in the Early Postoperative Period Predisposes to Cyclops Syndrome After Anterior Cruciate Ligament Reconstruction: A Risk Factor Analysis in 3633 Patients From the SANTI Study Group Database

BACKGROUND

Cyclops syndrome is characterized by a symptomatic extension deficit attributed to impingement of a cyclops lesion within the intercondylar notch. The syndrome is an important cause of reoperation after anterior cruciate ligament reconstruction (ACLR). It has been suggested that remnant-preserving ACLR techniques may predispose to cyclops syndrome, but there is very limited evidence to support this. In general terms, risk factors for cyclops syndrome are not well-understood.

PURPOSE

To determine the frequency of and risk factors for reoperation for cyclops syndrome in a large series of patients after ACLR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A retrospective analysis of prospectively collected data was performed, including all patients who underwent primary ACLR between January 2011 to December 2017. Patients undergoing major concomitant procedures were excluded. Demographic data, intraoperative findings (including the size of preserved remnants), and postoperative outcomes were recorded. Those patients who underwent reoperation for cyclops syndrome were identified, and potential risk factors were evaluated in multivariate analysis.

RESULTS

A total of 3633 patients were included in the study, among whom 65 (1.8%) underwent reoperation for cyclops syndrome. Multivariate analysis demonstrated that preservation of large remnants did not predispose to cyclops lesions (odds ratio [OR], 1.11; 95% CI, 0.63-1.93). The most important risk factor was extension deficit in the early postoperative period. If present at 3 weeks postoperatively, it was associated with a >2-fold increased risk of cyclops syndrome (OR, 2.302; 95% CI, 1.268-4.239; P < .01), which was increased to 8-fold if present 6 weeks after ACLR (OR, 7.959; 95% CI, 4.442-14.405; P < .0001). None of the other potential risk factors evaluated were found to be significantly associated with an increased frequency of cyclops syndrome.

CONCLUSION

Failure to regain full extension in the early postoperative period was the only significant risk factor for cyclops syndrome after ACLR in a large cohort of patients. Other previously hypothesized risk factors, such as preservation of a large anterior cruciate ligament remnant, did not predispose to the development of this debilitating postoperative complication.

Do Rotation and Measurement Methods Affect Reliability of Anterior Cruciate Ligament Tunnel Position on 3D Reconstructed Computed Tomography?

Background:

The literature has seldom investigated the anterior cruciate ligament (ACL) tunnel position while considering the effect of rotation of 3-dimensional computed tomography (3D-CT) images during measurements.

Hypothesis:

We hypothesized that (1) measurement of the ACL tunnel position in the femur and tibia through use of 3D-CT is considerably influenced by rotation of the 3D model and (2) there exists a reliable measurement method for ACL tunnel position least affected by rotation.

Study Design:

Controlled laboratory study.

Methods:

The 3D-CT images of 30 randomly selected patients who underwent single-bundle ACL reconstruction were retrospectively reviewed. For femoral tunnel assessments, rectangular reference frames were used that involved the highest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 1), the highest point of the intercondylar notch and outer margins of the lateral wall of the intercondylar notch (method 2), and the lowest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 3). For tibial tunnel assessments, rectangular reference frames with the cortical outline at the articular surface of the tibia (method A) and the cortical outline of the proximal tibia (method B) were used. For both femoral and tibial assessments, the tunnel positions at 5°, 10°, and 15° of rotation of the 3D model were compared with that at a neutral position.

Results:

The values measured by methods 1 and 3 showed significant differences at greater than 5° of rotation compared with the value at the neutral position, whereas method 2 showed relatively consistent results. However, the values measured with both methods A and B showed significant differences at greater than 5° of rotation compared with the value at the neutral position.

Conclusion:

The tunnel position on 3D-CT images was significantly influenced by rotation during measurements. For femoral tunnel position, measurement with a reference frame using the lateral wall of the intercondylar notch (method 2) was the least affected by rotation, with relatively consistent results.

Clinical Relevance:

This study demonstrates that measurement using the lateral wall of the intercondylar notch might be a consistent and reliable method for evaluating the ACL femoral tunnel position considering the effect of 3D-CT image rotation during measurements. However, both methods to measure tibial tunnel position described in this study were similarly affected by rotation.

In vivo gait kinematics of the knee after anatomical and non-anatomical single-bundle anterior cruciate ligament reconstruction-a prospective study

Background

The factors that influence functions of knees after anterior cruciate ligament reconstruction (ACLR) still remains uncertain. The functional restoration of knees after ACLR can be reflected on gait kinematics restoration. The purpose of this study was to evaluate the gait kinematics and clinical outcomes of knees after anatomical and non-anatomical single-bundle ACLR during level walking.

Methods

Thirty-four patients with unilateral primary single-bundle ACLR and 18 healthy people were recruited. Patients were divided into anatomical reconstruction group (AR group; n=13) and non-anatomical reconstruction group (Non-AR group; n=21) according to Bernard Quadrant method. The ACL graft orientations on coronal and sagittal planes were measured on 3D models from medical images. The 6 degrees of freedom (DOF) kinematics of knees and range of motion (ROM) of 6 DOF kinematics were measured with a portable optical tracking system. The comparison of 6 DOF kinematics and ROM of 6 DOF kinematics were performed between the ACLR knees and contralateral knees. The following assessments were also performed including clinical examination, KT-2000 arthrometer measurement, International Knee Documentation Committee (IKDC) and Lysholm scores.

Results

All patients reached a minimum follow-up of 6 months (10±4 months). For AR group and Non-AR group, no statistically significant differences were observed in gait kinematics between the ACLR knees and contralateral knees. No statistically significant differences between the ACLR knees and contralateral knees were observed in terms of ROM of 6 DOF kinematics in AR group. However, in Non-AR group, the ACLR knees exhibited significant ROM of anterior-posterior translation by approximately 0.5 cm than contralateral knees (P=0.0080). No statistically significant differences between the two groups were observed regarding IKDC subjective score, Lysholm score and KT-2000 arthrometer test.

Conclusions

The anatomical ACLR can restore close to normal gait kinematics and ROM of 6 DOF kinematics compared with non-anatomical ACLR. The ACL graft after anatomical ACLR simulated native ACL fibers to function in terms of graft orientation.

Primary ACL reconstruction using the LARS device is associated with a high failure rate at minimum of 6-year follow-up

PURPOSE

The Ligament Augmentation and Reconstruction System (LARS^®) is a synthetic ligament consisting of fibres made of polyethylene terephthalate. Despite the LARS being used as an anterior cruciate ligament (ACL) device for nearly 30 years and the well-documented complications from earlier synthetic ligament designs, there is a paucity of published medium- to long-term results. The aim of this study is to report the clinical and functional outcomes after ACL reconstruction using the LARS at a minimum follow-up of 6 years.

METHODS

Results of a single surgeon's entire cohort of 55 patients who underwent primary LARS ACL surgery were reviewed at a median of 7.8 years (6.0-9.4). Patient-reported outcome measures including the International Knee Documentation Committee (IKDC) score and 36-Item Short Form Health Survey (SF-36) were collected and clinical assessment consisted of range of motion (ROM) and the KT-1000 arthrometer to assess the side-side difference in the operative and non-operative knee. Mechanical failures of the graft were confirmed at revision surgery and a survivorship analysis was performed using the Kaplan-Meier method.

RESULTS

The overall mechanical failure rate was 17/51 (33.3%) with ruptures occurring at a median 3.9 years (0.6-8.8 years) following primary LARS ACL surgery. Secondary operative procedures were performed in 39.2% of patients. For intact grafts, there was no statistically significant difference is side-to-side ROM or anterior knee laxity and subjective scores revealed a median IKDC subjective score of 85.1 (26.4-100) and SF-36 physical component score of 94.1.

CONCLUSION

The rates of LARS ACL construct failure (33.3%) in this cohort are high and based on these results the LARS should not be considered as a graft option for primary ACL reconstruction.

LEVEL OF EVIDENCE

III, cohort study.