Current trends in the anterior cruciate ligament part 1: biology and biomechanics

Anterior Cruciate Ligament Reconstruction Augmentation With Bone Marrow Aspirate Concentrate, Demineralized Bone Matrix, and Suture Tape Shows No Difference in Outcomes-But Faster Functional Recovery-Versus Non-augmented Anterior Cruciate Ligament Reconstruction

PURPOSE

To compare outcomes after anterior cruciate ligament reconstruction (ACLR) with bone marrow aspirate concentrate (BMAC), demineralized bone matrix (DBM), and suture tape augmentation (STA) versus ACLR without biological augmentation or STA.

METHODS

We performed a prospective randomized controlled trial at a single institution to compare ACLR with BMAC, DBM, and STA (group A) versus ACLR without biological augmentation or STA (group NA). The study sought to include 100 patients. Skeletally mature patients younger than 25 years received quadriceps tendon autograft, whereas patients aged 25 years or older underwent allograft ACLR with an all-inside technique. Patients with concomitant meniscal pathologies were included. The primary outcomes compared were range of motion (ROM), limb symmetry, and patient-reported outcomes. Secondary outcomes included radiographic outcomes and surgical complications. Univariate and mixed-model regression analyses were used to compare outcomes.

RESULTS

Fifty-nine patients were included (29 patients in group A [11 female patients, 38%] and 30 patients in group NA [15 female patients, 50%]). Early ROM at 6 weeks (125° of flexion vs 109° of flexion, P < .0001) and limb symmetry at 12 weeks (80.6% vs 36.7% [delta, 43.9%], P < .001) were significantly improved in group A. At 2 years, International Knee Documentation Committee scores were similar (91.1 ± 12.7 vs 85.3 ± 10.8, P = .109). Quality-of-life subscores of the Knee Injury and Osteoarthritis Outcome Score were significantly enhanced in group A (85.2 ± 20.9 vs 72.1 ± 20.4, P = .042). In 22 patients (12 in group A and 10 in group NA), computed tomography scans were obtained at 6 months to compare bone tunnel healing. Overall, the mean increase in bone tunnel diameter was significantly smaller in group A than in group NA. No difference in graft rerupture or reoperation rate was observed. Reoperations were performed for stiffness in 7 of 59 patients (11.9%) (3 [10%] in group A vs 4 [13%] in group NA; P > .999).

CONCLUSIONS

There were no differences in International Knee Documentation Committee scores between groups at 2-year follow-up. Functional outcomes including early ROM and limb symmetry were significantly improved in patients who received ACLR with BMAC, DBM, and STA.

LEVEL OF EVIDENCE

Level II, randomized controlled trial.

Age not a primary risk factor for ACL injury-A comprehensive review of ACL injury and reinjury risk factors confounded by young patient age

Revision surgery after anterior cruciate ligament reconstruction (ACL-R) is hypothesized to be the result of an interplay between factors associated with the anatomy, physiological characteristics and environment of the patient. The multifactorial nature of revision ACL-R risk is difficult to quantify, and evidence regarding the independent roles of potentially important variables is inconsistent throughout the literature. Young patient age is often cited as one of the most prominent risk factors for reinjury after ACL-R. However, the association between a non-modifiable variable such as patient age and revision ACL-R risk is likely to be a spurious correlation due to the confounding effect of more important variables. From the perspective of healthcare professionals aiming to mitigate revision ACL-R risk through targeted interventions, awareness of factors like generalized joint hypermobility, bone morphology, muscle strength imbalances, and genetic factors is critical for the individualized risk assessment of patients with ACL injury. The aim of this current concepts article is to raise awareness of the essential anatomical, physiological, and activity-related risk factors associated with ACL injury and reinjury risk that are likely captured and confounded by patient age. LEVEL OF EVIDENCE: Level V.

Patients with ACL injury have lower and more posterior position of proximal tibiofibular joint than patients with intact ACL

BACKGROUND

Knees with anterior cruciate ligament (ACL) injury have distinct knee bone morphology. However, the correlation between ACL injury and morphology of the proximal tibiofibular joint has not been investigated.

PURPOSE

To compare proximal tibiofibular joint morphology in patients with injured and intact ACLs to aid in predicting and preventing ACL injuries.

MATERIAL AND METHODS

A total of 50 patients with ACL injury and 50 individuals without structural knee damage (revealed by magnetic resonance imaging [MRI]) were included in this study. In the anteroposterior knee radiographs, the length between the proximal end of the fibular head and the medial and lateral tibia joint line were measured. In the axial knee MRI scans with the most proximal part of the fibular head, the distance calculation was performed between the most anterior point of the tibia plateau (MATP) and the most anterior point of fibular head (MAFH).

RESULTS

The mean length from the proximal end of the fibular head and the medial and lateral tibial joint lines was 8.7 ± 2.8 mm and 13.2 ± 2.6 mm in the ACL-injured group, and 6.5 ± 2.8 mm and 11.1 ± 2.4 mm in the control group. The length for both medial and lateral sides was significantly greater in the ACL-injured group. The length between the MATP and MAFH was significantly larger in the ACL-injured group than the control group.

CONCLUSION

A large distance between the proximal end of the fibular head and the tibial joint line and knees with posterior fibular head placement would be another anatomic risk factor of ACL injury.

Anatomic double-bundle transtibial anterior cruciate ligament reconstruction restores graft length changes but leads to larger graft bending angles

PURPOSE

The purpose of this study was to evaluate the femoral tunnel position using a modified anatomic transtibial (TT) double-bundle anterior cruciate ligament reconstruction (DBACLR) and to investigate the knee kinematics, graft length and graft bending angle following DBACLR.

METHODS

Ten patients who underwent DBACLR using the modified TT technique were included in the study. All patients performed a single-legged lunge under a dual fluoroscopic imaging system to assess the 6 degrees of freedom tibiofemoral kinematics. Femoral tunnel position was evaluated via postoperative three-dimensional (3D) computed tomography. The area centroids of anteromedial (AM) and posterolateral (PL) bundles were determined on 3D knee models. The lengths of AM and PL bundles, as well as graft bending angle at the femoral tunnel aperture, were measured by created virtual fibres.

RESULTS

The reconstructed knee rotated more externally compared with the contralateral knee between 0° and 60° (p ≤ 0.049). There is no significant difference in the length change of AM bundle (n.s.) and PL bundle (n.s.) between the two sides from 0° to 120° during the lunge motion. The maximum graft bending angle at the femoral tunnel aperture occurred at 0° of knee flexion, with the AM graft bending angle was 72.6° ± 9.0° and the PL graft bending angle was 90.3° ± 9.7°.

CONCLUSION

The modified TT technique used in this study could achieve anatomical ACL reconstruction, restoring graft length change patterns compared to contralateral knees. However, residual rotational instability of the reconstructed knee was observed after DBACLR, despite achieving anatomic tunnel placement. Therefore, double-bundle reconstruction may not sufficiently address the persistent rotational instability of the knee. Additionally, larger graft bending angles at the femoral tunnel aperture were found with the modified TT technique. Therefore, further improvement to the TT technique should focus on reducing the graft's curvature while maintaining the anatomical properties of the knee joint. The findings of this study highlight the need for improved surgical techniques to address residual rotational instability and optimise graft curvature. These improvements are crucial for enhancing patient outcomes and long-term joint function following ACL reconstruction.

LEVELS OF EVIDENCE

Level II.

Graft Selection in Anterior Cruciate Ligament Reconstruction: A Comprehensive Review of Current Trends

Anterior cruciate ligament (ACL) injuries are common in sports and often require surgical intervention, e.g., ACL reconstruction (ACLR), aimed at restoring knee stability and enabling a return to pre-injury activity levels. The choice of graft is crucial, impacting biomechanical properties, clinical outcomes, and complication rates, and is especially important in revision surgeries after graft failure. Over the past 30 years, trends in graft selection have evolved towards more individualized approaches, considering factors such as patient activity level, prior injuries, and tissue availability. In Europe, autografts like hamstring tendon (HT), bone-patellar tendon-bone (BTB), and quadriceps tendon (QT) are preferred, with the increasing use of QT grafts. This review synthesizes the current literature on graft selection and its influence on ACLR outcomes.

Validation of CLASS MRI for personalized ACL footprints identification

PURPOSE

In modern anterior cruciate ligament (ACL) surgery, the focus is usually on anatomical reconstruction to restore the natural kinematics of the knee. The individual optimal positioning of the ACL footprints (FPs) in primary surgery is still controversial and, especially in revision surgery, difficult to realize surgically. In this regard, a new MRI-based sequence, the Compressed Lateral and anteroposterior Anatomic Systematic Sequence (CLASS) with marked femoral and tibial FPs as a template, could help. The purpose of this study was to (1) validate the reliability and reproducibility of the localization of femoral and tibial FPs of ACL in the generation of CLASS and (2) compare the identification of ACL FPs by CLASS with previously described methods.

METHODS

Magnetic resonance imaging (MRI) of uninjured knees from a predominantly young cohort is used to apply the CLASS algorithm. ACL FPs were subsequently identified by a board-certified radiologist and an orthopaedic knee surgeon. Intraobserver reliability and interobserver reproducibility were assessed. Measurements of the ACL FPs according to established methods were performed and compared with the results from the literature.

RESULTS

Identification of ACL FPs and generation of CLASS images resulted in 'almost perfect' reliability and reproducibility. Most measurements also showed 'almost perfect' consistency. Statistical analysis showed significant variations between the deep-shallow and high-low positions when compared to the published literature.

CONCLUSIONS

The CLASS MRI sequence is a reliable and reproducible method for identifying ACL FPs. The observed variability in the location of the ACL FP underlines the importance of a patient-specific surgical approach.

LEVEL OF EVIDENCE

Level II.

Factors influencing clavicular tunnel widening after single bundle coracoclavicular ligament reconstruction

BACKGROUND

The coracoclavicular ligament reconstruction (CLR) technique for the treatment of acromioclavicular joint (ACJ) dislocation has gained immense clinical popularity. However, this technique also has some limitations including complications such as distal clavicle fractures, coracoid fractures, bone tunnel widening, implant failure, and loss of reduction. A study was conducted to analyse the extent of CTW after single-bundle CLR by measuring radiographic parameters to determine its relationship with clinical variables to reduce the risk of clavicular tunnel widening (CTW), thereby providing important insights for clinical practice.

METHODS

This retrospective analysis was conducted at Affiliated Fuyang People's Hospital of Bengbu Medical University, and data from 96 patients who underwent single-bundle CLR for type III-VI ACJ dislocation between January 2018 and December 2023 were initially collected. Finally, 84 patients met the inclusion criteria (63 male and 21 female, mean age: 49.5 ± 12.36 years). The clavicle tunnel (CT) width and coracoclavicular distance (CCD) was measured immediately postoperatively and at 6 months follow up using radiographic imaging, and the degree of expansion at 6 months was recorded. Preoperative variables including patient sex, age, injury cause, injury side, body mass index (BMI), Rockwood classification, extent of the CCD after surgery, and the CT location were recorded to analyze their correlation with the extent of CTW at 6 months follow up.

RESULTS

With an average follow-up duration of 10 months (range: 6-18 months). Both the extent of the CCD and CTW measured at 6 months postoperatively were differently enlarged, compared to early postoperative period (EPO) (P < 0.05). The results showed that there were no statistically significant differences in the CTW at 6 months postoperatively with respect to patients' sex, causes of injury, sides of injury, and Rockwood classification types(P > 0.05). However, the location of CT was significantly associated with the extent of CTW at 6 months postoperatively (P < 0.05).

CONCLUSIONS

The location of CT drilling is a significant factor that affects tunnel widening. When the drilling site is situated closer to the conoid tubercle, the extent of CTW is greater than when the tunnel is located farther from the conoid tubercle.

Patient's Height and Sex Predict Graft Diameter: A Cohort Study of 4,519 Patients With Primary Anterior Cruciate Ligament Reconstruction Using Semitendinosus Autograft

PURPOSE

To determine whether anthropometric measurements (height and weight), sex, age, and preinjury Tegner Activity Scale (TAS) were predictors of the quadrupled semitendinosus (ST) graft diameter in primary anterior cruciate ligament reconstruction.

METHODS

A total of 4,519 patients who underwent primary anterior cruciate ligament reconstruction with a quadrupled ST autograft were included. Anthropometric measurements (height and weight), sex, age, and preinjury TAS were collected. Correlation coefficients and multiple linear regression analysis were used to determine the relationships among graft diameter and anthropometrics measurements (height and weight), sex, age, and preinjury TAS.

RESULTS

The diameter of the quadrupled ST graft was correlated positively to height (r = 0.021, P < .001), age (r = 0.005, P < .001), and weight (r = 0.004, P = .001) and negatively to female sex (r = -0.297, P < .001). A regression equation was estimated to predict the ST graft diameter for men as 4.245 + 0.021 × height (cm) + 0.004 × age (years) + 0.005 × weight (kg) and for women as 3.969 + 0.021 × height (cm) + 0.004 × age (years) + 0.005 × weight (kg).

CONCLUSIONS

Height, age, and weight were positively correlated, whereas female sex was negatively correlated, to the diameter of the quadrupled ST graft. Knowledge of these factors can be used for the preoperative estimation of the graft diameter which can be helpful for appropriate graft choice.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

ACL anatomy: Is there still something to learn?

BACKGROUND

The different bony and soft tissue reference points and the micro and macroscopic structures of the knee continue to be the object of focused study and analysis. Upon reviewing the most recent literature, we saw the wide spectrum of studies that seek to define the different anatomical aspects of the anterior cruciate ligament (ACL).

PURPOSE

The purpose of this paper is to review the most recent publications on the ACL and its morphology in which its microscopic composition and macroscopic anatomy are addressed.

RESULTS

The ACL consists of typeI (90%) and typeIII (10%) collagen matrix. Its length ranges from 27 to 38mm and its width from 10 to 12mm. The ACL cross-section area measures an average of 44mm2, and its shape resembles that of an hourglass or a bow tie. ACL bundles have been defined as anteromedial, intermediate, and posterolateral. Femoral and tibial footprints were seen to present a high degree of variability in shape and size. Furthermore, the blood supply is given by the medial genicular artery and innervation by the tibial nerve branches. Additionally, the ACL functionally prevents anterior translation of the tibia and stabilizes against the internal rotation of the tibia and valgus angulation of the knee.

CONCLUSIONS

There is great variability in the anatomy of the ACL as well as its attachment sites. At the same time, the shape and size of its footprint has become a factor in determining individualized ACL reconstruction. The persistence of morphological variability in the aging of the ACL and important aspects of surgical planning and decision making with respect to anatomical risk factors suggest that further studies are called for.

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.

A novel approach for anterior cruciate ligament tibial avulsion fracture: arthroscopic modified suture bridge fixation technique

INTRODUCTION

Anterior cruciate ligament (ACL) tibial avulsion fracture is a rare injury, which usually happens in adults with traffic accidents or sports injuries. Surgery interventions are common treatment methods, they can restore knee function and help to return to normal life. In this study, we described an arthroscopic modified suture bridge fixation technique for ACL tibial avulsion fractures and explored the feasibility and therapeutic effects.

MATERIALS AND METHODS

This retrospective study reviewed data from January 2020 to May 2022. Data were collected on 18 patients (10 males and 8 females) with ACL tibial avulsion fractures and underwent arthroscopic modified suture bridge fixation technique. The study analyzed surgical data about intraoperative blood loss, operation time, hospital stay, fracture healing time, and visual analog scale (VAS). Functional evaluation of the knee joint was performed using the anterior drawer test, Lysholm knee scoring scale, International Knee Documentation Committee (IKDC), and knee range of motion (ROM).

RESULTS

All 18 patients were followed up between 12 and 20 months, with an average of 15.22 ± 1.96 months. The intraoperative blood loss was approximately 15-40 mL, averaging 25.78 ± 6.19 mL. The operation time was 65-85 min, with a mean of 74.89 ± 4.86 min. The hospital stay of patients was 3-5 days, with a mean of 3.89 ± 0.76 days. The mean fracture healing time was 8-12 weeks after surgery, with a mean of 9.22 ± 1.7 weeks. All incisions healed grade I without infection. There were no internal fixation failures, neurovascular injuries, and lower extremity deep venous thrombosis. The anterior drawer test was negative in all patients. At the final follow-up, the mean VAS score was 0-3, averaging 1.56 ± 0.71. The Lysholm score of the injured knee was 89-96, with an average of 92.50 ± 2.50; the IKDC score was 88-93, with an average of 90.44 ± 1.89; the knee ROM was 110-126°, with an average of 120.67° ± 4.31°.

CONCLUSION

Results demonstrated that the modified suture bridge fixation technique under arthroscope could provide reliable fixation and favorable clinical effects for ACL tibial avulsion fractures. This is a simple, minimally invasive, effective, and clinically applicable surgical method for ACL tibial avulsion fracture.

Italian research on anterior cruciate ligament: a bibliometric analysis

INTRODUCTION

This study analysed the trend of publications on anterior cruciate ligament (ACL) in Italy. It was hypothesised that publications on this topic have quickly increased in recent years due to increased knowledge of both clinical and radiological pathology.

METHODS

PubMed and Scopus were accessed on 29/11/2023. This retrieved 838 articles from PubMed and 1050 from Scopus. We analysed the top 10 authors, and journals in publication numbers, citation numbers, and citations per year. We have also looked at the top 10 institutions publishing on anterior cruciate ligament from Scopus as PubMed does not give this information in the output. Data mining was performed using the Orange software, Mac version 3.32.0 ( https://orangedatamining.com/ ) from the titles of all articles. A word cloud analysis of titles, authors, journals and universities was performed.

RESULTS

The peak of citations was in 2017 with 1529, whilst the peak of publications was in 2019 with 59 articles published. Analysing the number of publications and citations for the journal, the most impacted journal is Knee Surgery, Sports Traumatology, Arthroscopy with 5472 citations and 183 articles, followed by The American Journal of Sports Medicine, with 2722 citations and 56 articles and Arthroscopy with 1990 citations and 62 articles. Considering also international collaborations, the most cited author is Della Villa F. in 2020 with 43.67 citations per year. The Italian author with the major number of publications is Zaffagnini S. with 39 articles, whilst the author with the higher number of citations is Aglietti P. with 1612 citations.

CONCLUSIONS

ACL reconstruction has gained growing interest amongst the scientific community. Publications and citations presented a rising trend, the majority of the highly cited papers were contributed by few centres, and clinical trials were the most cited study designs. The long-term outcomes of ACL lesions have attracted interest. The authors hypothesised that shortly there will be an increase in articles analysing the results of ACL revisions, the use of lateral extra-articular tenodesis, and meniscus transplants.

LEVEL OF EVIDENCE IV

Cross-Sectional Study.

ACL anatomy: Is there still something to learn?

BACKGROUND

The different bony and soft tissue reference points and the micro and macroscopic structures of the knee continue to be the object of focused study and analysis. Upon reviewing the most recent literature, we saw the wide spectrum of studies that seek to define the different anatomical aspects of the anterior cruciate ligament (ACL).

PURPOSE

The purpose of this paper is to review the most recent publications on the ACL and its morphology in which its microscopic composition and macroscopic anatomy are addressed.

RESULTS

The ACL consists of type I (90%) and type III (10%) collagen matrix. Its length ranges from 27 to 38mm and its width from 10 to 12mm. The ACL cross-section area measures an average of 44mm2, and its shape resembles that of an hourglass or a bow tie. ACL bundles have been defined as anteromedial, intermediate, and posterolateral. Femoral and tibial footprints were seen to present a high degree of variability in shape and size. Furthermore, the blood supply is given by the medial genicular artery and innervation by the tibial nerve branches. Additionally, the ACL functionally prevents anterior translation of the tibia and stabilizes against the internal rotation of the tibia and valgus angulation of the knee.

CONCLUSIONS

There is great variability in the anatomy of the ACL as well as its attachment sites. At the same time, the shape and size of its footprint has become a factor in determining individualized ACL reconstruction. The persistence of morphological variability in the aging of the ACL and important aspects of surgical planning and decision making with respect to anatomical risk factors suggest that further studies are called for.

Information videos posted on Instagram by orthopaedics and sports traumatology surgeons mostly explain surgical technique, and the least mentioned topics are injury prevention and complications

PURPOSE

Social media has become the new information acquisition platform for all content producers. In the current literature, there are no studies examining the content quality and the strengths and weaknesses of videos on Instagram that explain anterior cruciate ligament (ACL) injuries, which is the most discussed topic of sports surgery. The aim of this study was to evaluate the quality, strengths and weaknesses of information pertaining to ACL surgery that is disseminated on Instagram.

METHOD

An Instagram search was conducted from 30 May 2023 to 30 January 2024. The search encompassed six languages (English, Spanish, German, French, Italian and Turkish) and was performed by six different observers. The investigation focused on eight subheadings derived from current literature on the ACL. These subheadings were addressed in Instagram videos, covering ACL biology or biomechanics, injury mechanism, injury prevention, injury evaluation, surgical technique, injury or surgery complications, injury rehabilitation process and return to sport or work.

RESULT

The content was assessed of 127 videos from 127 Instagram accounts, spanning six different languages. Across the review of eight subheadings, the average number covered for the entire group was 3 (range, 0-8). Further analysis revealed that surgical technique was the most frequently mentioned subheading for the whole group (68.5%), followed by injury evaluation (54.3%). Prevention (10.2%) and complications (19.6%) were the least mentioned subheadings. The number of followers showed a correlation with video content quality.

CONCLUSION

Although the video quality scores were found to be moderate, the content often focused on surgery and evaluation subheadings. The prevalence of incomplete information underscores the importance of developing strategies to ensure more comprehensive and accurate dissemination of medical knowledge.

LEVEL OF EVIDENCE

Level V.

Can the ACL Cross-Sectional Area Be Predicted? Size Correlation and Proportion between the ACL Cross-Sectional Area and the Femoral Intercondylar Notch Area

The purpose of this study was to reveal the correlation and proportion between the anterior cruciate ligament (ACL) cross-sectional area and the femoral intercondylar notch area. Sixty-three subjects (33 female and 30 male) less than 50 years old were included in this study. All subjects complained of knee pain, although magnetic resonance imaging (MRI) showed no structural damage of the knee. Using the T2 axial slice of the MRI perpendicular to the bone shaft, the ACL cross-sectional area and the femoral intercondylar notch area were measured. Measurements were made at the most proximal (S1), ⅓ (S2), ⅔ (S3), and the most distal (S4) Blumensaat's line levels. The correlation and the proportion between the ACL cross-sectional area and the notch area were calculated. The ACL cross-sectional area was: S1: 35.9 ± 10mm2, S2: 59.9 ± 14mm2, S3: 67.2 ± 19.5mm2, and S4: 70.7 ± 20.3mm2. The notch area was: S1: 215.5 ± 43mm2, S2: 311.8 ± 65mm2, S3: 453.8 ± 86mm2, and S4: 503.7 ± 99.8mm2. The ACL cross-sectional area and the notch area were found to be significantly correlated at the S3 (Pearson's coefficient correlation: 0.510, p = 0.000) and S4 (Pearson's coefficient correlation: 0.529, p = 0.000) levels. The proportion of the ACL cross-sectional area to the notch area was 15% in S3 and 14% in S4. The ACL cross-sectional area was found to be significantly correlated with the femoral intercondylar notch area at the distal level of the Blumensaat's line. The ACL cross-sectional area was found to be approximately 15% of the notch area. The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area. This finding can be useful for achieving greater accuracy in anatomical ACL reconstruction. LEVEL OF EVIDENCE:  III.

App-Based Analysis of Fluoroscopic Images According to Bernard-Hertel Method for the Determination of Femoral Tunnel Positioning in Anterior Cruciate Ligament Reconstruction

The accurate positioning of the femoral tunnel is crucial for the success of anterior cruciate ligament reconstruction. Malpositioning of the tunnel is believed to be one of the most important reasons for graft failure. While use of anatomic landmarks and industry-supplied aiming devices aid the surgeon in placing the drill pin in the correct position, fluoroscopic imaging is an additional tool used intraoperatively to verify pin placement. While interpretation of fluoroscopic imaging is frequently based on eyeball measurement, a more accurate analysis of a lateral image uses the quadrant method by Bernard-Hertel. This method has been primarily used for scientific research due to its complexity and has not been integrated into clinical routine yet. We present a digital app-based approach to easily quantify the femoral pin position based on the quadrant method. This approach is mobile and easy to use. Quantification of pin position of femoral bone tunnel on a lateral fluoroscopic image may be used for quality control and teaching purposes or may provide the surgeon with additional information during ACL reconstruction.

Preoperative joint line obliquity, a newly identified factor for overcorrection, can be incorporated into a novel preoperative planning method to optimise alignment in high tibial osteotomy

PURPOSE

The aim of this study was to analyse the factors associated with additional postoperative alignment changes after accurate bony correction by selecting only patients with well-performed bony correction as planned and develop a method of incorporating significant factors into preoperative planning.

METHODS

Among 104 consecutive patients who underwent medial open wedge high tibial osteotomy (MOWHTO) between October 2019 and July 2022, 61 with well-performed bony corrections were retrospectively reviewed. The major criterion for well-performed bony correction was a difference of <1° between the simulated medial proximal tibial angle (MPTA) and the actual postoperative MPTA as measured in three dimensions. Radiographic parameters, such as the joint line convergence angle (JLCA) and joint line obliquity (JLO), were measured preoperatively and postoperatively, utilising standing and supine whole lower extremity anteroposterior, valgus and varus stress radiographs. Multiple linear regression analysis identified the factors affecting alignment changes, and a prediction model was developed. A method for applying this prediction model to preoperative planning was proposed.

RESULTS

Preoperative JLCA on standing (preJLCAstd ), preoperative JLCA on 0° valgus stress radiograph (vgJLCA0 ), and preoperative JLO (preJLO) were significantly correlated with JLCA change (∆JLCA) (p < 0.001, p < 0.001, p = 0.006). The prediction model was estimated as ∆JLCA = 0.493 × (vgJLCA0 ) - 0.727 × (preJLCAstd ) + 0.189 × (preJLO) - 1.587 in. (R = 0.815, modified R2  = 0.646, p < 0.001). The proposed method resulted in a reduced overcorrection rate (p = 0.003) and an improved proportion of acceptable alignments (p = 0.013).

CONCLUSION

PreJLCAstd , vgJLCA0  and preJLO can be used to estimate ∆JLCA. PreJLO was recently identified as a significant factor associated with additional alignment changes. Utilising the proposed preoperative planning and a prediction model with these factors shows promise in calibrating postoperative alignment after MOWHTO.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Patient specific instrumentation in ACL reconstruction: a proof-of-concept cadaver experiment assessing drilling accuracy when using 3D printed guides

INTRODUCTION

Accurate positioning of the femoral tunnel in ACL reconstruction is of the utmost importance to reduce the risk of graft failure. Limited visibility during arthroscopy and a wide anatomical variance attribute to femoral tunnel malposition using conventional surgical techniques. The purpose of this study was to determine whether a patient specific 3D printed surgical guide allows for in vitro femoral tunnel positioning within 2 mm of the planned tunnel position.

MATERIALS AND METHODS

A patient specific guide for femoral tunnel positioning in ACL reconstruction was created for four human cadaveric knee specimens based on routine clinical MRI data. Fitting properties were judged by two orthopedic surgeons. MRI scanning was performed both pre- and post-procedure. The planned tunnel endpoint was compared to the actual drilled femoral tunnel.

RESULTS

This patient specific 3D printed guide showed a mean deviation of 5.0 mm from the center of the planned femoral ACL origin.

CONCLUSION

In search to improve accuracy and consistency of femoral tunnel positioning in ACL reconstruction, the use of a patient specific 3D printed surgical guide is a viable option to explore further. The results are comparable to those of conventional techniques; however, further design improvements are necessary to improve accuracy and enhance reproducibility.

Isolated meniscus allograft transplantation with soft-tissue technique effectively reduces knee laxity in the presence of previous meniscectomy: In-vivo navigation of 18 consecutive cases

OBJECTIVES

Although meniscal allograft transplantation (MAT) is a well-established procedure with satisfactory clinical results, limited in vivo kinematic information exists on the effect of medial and lateral MAT performed in the clinical setting. The purpose of the present study was to evaluate the biomechanical effect of arthroscopic isolated medial and lateral MAT with a soft-tissue fixation on pre- and post-operative knee laxity using a surgical navigation system.

METHODS

18 consecutive patients undergoing MAT (8 medial, 10 lateral) were enrolled. A surgical navigation system was used to quantify the anterior-posterior displacement at 30 and 90 degrees of knee flexion (AP30 and AP90), the varus-valgus rotation at 0 and 30 degrees of knee flexion (VV0 and VV30) and the dynamic laxity on the pivot-shift test (PS), which was determined through the anterior displacement of the lateral tibial compartment (APlat) and posterior acceleration of the lateral tibial compartment during tibial reduction (ACC). Data from laxity before and after MAT were compared through paired t-test (p ​< ​0.05).

RESULTS

After medial MAT, there was a significant decrease in tibial translation of 3.1 ​mm (31%; p ​= ​0.001) for AP30 and 2.3 ​mm (27%; p ​= ​0.020) for AP90, a significant difference of 2.5° (50%; p ​= ​0.002) for VV0 and 1.7° (27%; p ​= ​0.012) for VV30. However, medial MAT did not determine any reduction in the PS kinematic data. Lateral MAT determined a significant decrease in the tibial translation of 2.5 ​mm (38%; p ​< ​0.001) for AP30 and 1.9 ​mm (34%; p ​= ​0.004) for AP90 as well as a significant difference of 3.4° (59%; p ​< ​0.001) for VV0 and of 1.7° (23%; p ​= ​0.011) for VV30. There was also a significant reduction of the PS of 4.4 ​mm (22%; p ​= ​0.028) for APlat and 384.8 ​mm/s2 (51%; p ​= ​0.005) for ACC.

CONCLUSION

MAT with soft-tissue fixation results in a significant laxity reduction in an in-vivo setting. Medial MAT improved knee kinematics by determining a significant reduction with particular emphasis on AP translation and VV manoeuvre. Conversely, Lateral MAT determined a massive reduction of the PS and a mild decrease of the AP translation and VV manoeuvre.

STUDY DESIGN

Controlled laboratory study.

ACL Volume Measurement Using a Multi-truncated Pyramid Shape Simulation

Purpose

The purpose of this study was to measure anterior cruciate ligament (ACL) volume in a newly reported multi-truncated pyramid shape simulation using axial magnetic resonance imaging (MRI) for the detailed knowledge of the ACL anatomy.

Methods

Fifty subjects (27 female and 23 male, average age: 23 ± 7.8) visiting our clinic with knee pain and in whom MRI showed no structural injury were included in this study. Using the axial image of the MRI, four deferent levels of the cross-sectional area of the ACL were measured. ACL height was measured as the distance between the most proximal and distal slices of the MRI. ACL volume was calculated using a multi-truncated pyramid shape simulation. Femoral intercondylar notch height, area, and trans-epicondylar length (TEL) were also measured using MRI.

Results

The measured top, proximal 1/3, distal 1/3, and bottom of the ACL cross-sectional area were, 36.8 ± 10.7, 59.9 ± 15.4, 66.4 ± 20.8, and 107.3 ± 21.1mm2, respectively. ACL height was 26.3 ± 3.9 mm. Using these data, the calculated ACL volume was 1755 ± 874mm3. Significant correlations were observed between ACL volume and notch height, area, and TEL.

Conclusion

Similar ACL volume with previous reports was obtained in this simple and easy multi-truncated pyramid shape simulation from axial MRI evaluation. Significant correlation was observed between ACL volume and knee bony morphology. The ability of surgeons to measure ACL volume simply and effectively can be useful for the detailed ACL anatomical knowledge, and also for prediction and prevention of ACL injury.Level of evidence: IV, Case series.

Effect of anteromedial portal location on femoral tunnel inclination, length, and location in hamstring autograft-based single-bundle anterior cruciate ligament reconstruction: a prospective study

BACKGROUND

Portal positioning in arthroscopic anterior cruciate ligament reconstruction is critical in facilitating the drilling of the femoral tunnel. However, the traditional approach has limitations. A modified inferior anteromedial portal was developed. Therefore, this study aims to compare the modified and conventional far anteromedial portals for femoral tunnel drilling, assessing factors such as tunnel length, inclination, iatrogenic chondral injury risk, and blowout.

MATERIAL AND METHODS

Patients scheduled for hamstring autograft-based anatomical single-bundle arthroscopic anterior cruciate ligament reconstruction were divided into two groups: modified and far anteromedial groups. Primary outcomes include differences in femoral tunnel length intraoperatively, tunnel inclination on anteroposterior radiographs, and exit location on lateral radiographs. Secondary outcomes encompass tunnel-related complications and reconstruction failures. To identify potential risk factors for shorter tunnel lengths and posterior exits, regression analysis was conducted.

RESULTS

Tunnel parameters of 234 patients were analyzed. In the modified portal group, femoral tunnel length and inclination were significantly higher, with tunnels exhibiting a more anterior exit position (p < 0.05). A higher body mass index exerted a negative influence on tunnel length and inclination. However, obese patients in the modified portal group had longer tunnels, increased inclination, and a lower risk of posterior exit. Only a few tunnel-related complications were observed in the far anteromedial group.

CONCLUSION

The modified portal allowed better control of tunnel length and inclination, ensuring a nonposterior femoral tunnel exit, making it beneficial for obese patients.

Reliability of the Tibial Spine Versus ACL Stump in Assisting Tibial Tunnel Positioning During ACL Reconstruction: Analysis Based on 3-Dimensional Computed Tomography Modeling

BACKGROUND

Several techniques have been used by surgeons for anatomic tibial tunnel placement in anterior cruciate ligament (ACL) reconstruction, including the ACL stump positioning (ASP) technique and the tibial spine positioning (TSP) technique.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate whether bony landmarks (medial and lateral tibial spine [MLTS]) can be a reliable reference for improving the accuracy of tibial tunnel placement in anatomic single-bundle ACL reconstruction compared with the ACL stump. It was hypothesized that the MLTS would not be a reliable bony landmark for tibial tunnel placement.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The 3-dimensional computed tomography images of 111 patients who underwent ACL reconstruction between 2020 and 2021 were included in this study. For tibial tunnel placement, the ASP technique was used in 49 patients, and the TSP technique was used in 62 patients. The 3-dimensional computed tomography images were reconstructed to enable measurements of the locations of the MLTS and tunnel center based on a grid method. Statistical analysis was conducted to compare the MLTS location and tibial tunnel position as well as the accuracy (mean distance of each actual location from the anatomic center) and precision (standard deviation of the accuracy, indicating the reproducibility of the tunnel position) of the tunnel position between the ASP and TSP groups.

RESULTS

Significant differences were observed between the ASP and TSP groups in terms of the tibial tunnel position on the mediolateral axis (46.7% ± 2.0% vs 45.9% ± 2.2%, respectively; P = .034), while no significant differences were found in terms of the accuracy (4.1% vs 4.6%, respectively; P = .259) or precision (2.1% vs 2.1%, respectively; P = .259) of tibial tunnel positioning between the 2 groups.

CONCLUSION

In anatomic single-bundle ACL reconstruction, the use of the MLTS for tibial tunnel placement achieved comparable accuracy and precision compared with the use of ACL remnants, supporting its role as a reliable bony landmark in tibial tunnel positioning.

Quadrupled Semitendinosus Anterior Cruciate Ligament Reconstruction Without the Use of Tourniquet and Minimal Instrumentation: The "Double D" Technique

The hamstring tendons are among the most common autografts used for anterior cruciate ligament reconstruction. Typically, the ipsilateral knee's gracilis and semitendinosus tendons are harvested. More recently, studies have described the use of just 1 of the tendons (the semitendinosus [ST]) in a tripled or quadrupled configuration, particularly in all-inside reconstructions. Instead of using a double gracilis and ST, a quadrupled ST tendon allows for a graft with enough diameter to more closely mimic the natural anterior cruciate ligament while lowering the likelihood of graft rupture. The use of tourniquets has been reported to increase the risk of complications, particularly deep vein thrombosis. This Technical Note describes an anterior cruciate ligament reconstruction performed with a quadrupled ST, without the use of a tourniquet, and with only the reamers and a tibial guide as surgical instrumentation.

High anteromedial insertion reduced anteroposterior and rotational knee laxity on mid-term follow-up after anatomic anterior cruciate ligament reconstruction

Background

The position of the femoral insertion has a great influence on the laxity of the knee joint after ACLR, especially for rotational laxity.

Purpose

To compare the effects of different femoral tunnel positions on knee stability after arthroscopic anterior cruciate ligament reconstruction (ACLR).

Methods

The clinical outcomes of 165 patients after autograft ACLR were analyzed retrospectively. The patients were separated into three groups according to the position of the femoral tunnel, as follows: low center (LC) group, 53 patients; high center (HC) group, 45 patients; and high anteromedial (HAM) group, 67 patients. The side-to-side differences (SSDs) in anteroposterior knee laxity measured using a KT-2000 arthrometer and the pivot shift test (PST) pre- and postoperatively were compared among the three groups and analyzed.

Results

After 5 years postoperatively, the SSD in the anteroposterior knee laxity in the three groups was significantly decreased postoperatively compared with preoperatively in knees; meanwhile, the negative PST rate was significantly increased in the three groups. The postoperative SSD in anteroposterior knee laxity was significantly increased in the HC group compared with the LC and HAM groups (1.5 ± 1.3 VS 1.0 ± 1.1 VS 1.0 ± 1.0, P<0.05). The negative postoperative PST rate was higher in both the LC and HAM groups than in the HC group (84.9% VS 91.0% VS 71.1%, P<0.05), and there was no significant difference in the negative PST rate between the LC and HAM groups (84.9% VS 91.0%, P>0.05). The negative postoperative PST rate was significantly higher in the HAM group than in the LC and HC groups for patients with a high degree of laxity preoperatively (31.3% VS 3.3% VS 14.4%, P>0.05).

Conclusion

Patients in HAM group showed better control over anteroposterior laxity, rotational laxity, and subjective knee function compared to other groups post operation. Therefore, the HAM point is the closest to the I.D.E.A.L point concept, and is recommended as the preferred location for the femoral tunnel in ACLR.

The patient with patellar instability has a stenotic intercondylar notch and a thin anterior cruciate ligament: a retrospective comparative study

BACKGROUND

Patellar instability (PI) usually combines with morphological abnormalities of femoral condyles that may affect the morphology of the intercondylar notch and anterior cruciate ligament (ACL), which are important in individualized ACL reconstruction. This study aimed to investigate the morphological characteristics of the intercondylar notch and ACL in patients with PI.

METHODS

80 patients with PI and 160 age- and gender-matched controls from January 2014 to June 2022 were studied. Morphological measurements of the femoral condyles included intercondylar notch height, notch width, medial condylar width, lateral condylar width, bicondylar width, notch width index, notch angle, lateral femoral condyle ratio (LFCR), condyle flexion angle, and posterior tibial slope. Morphological measurements of the ACL included ACL length, inclination angle, and ACL size. The measurements were compared between PI and control groups, and between males and females in PI group. The independent samples t-test was performed to examine differences in continuous variables. The chi-square test was used for comparing categorical variables.

RESULTS

The intercondylar notch width, bicondylar width, notch width index, and notch angle were significantly smaller, while the LFCR was significantly larger in PI group than those of control group (p < 0.05). The ACL thickness (0.70 ± 0.16 cm vs 0.80 ± 0.21 cm, p = 0.023) and width (0.54 ± 0.14 cm vs 0.60 ± 0.13 cm, p = 0.029) were significantly smaller in PI group. The notch width was significantly smaller in female patients than males in PI group, but no significant difference was observed in the notch width index and notch angle (p > 0.05). No sex difference related to the morphology of the ACL was found.

CONCLUSIONS

The patient with PI had a stenotic intercondylar notch and a thin ACL. No significant sex difference in the intercondylar notch stenosis and ACL size was observed. The morphology of the intercondylar notch and ACL should be taken into consideration when planning individualized ACL reconstruction in the presence of PI.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

[Translated article] Three years follow-up outcome of 4-strand semitendinous-gracilis anterior ligament reconstruction in women: A matched-cohort study

INTRODUCTION

Women carry out a greater risk of anterior cruciate ligament (ACL) rupture. However, outcomes following ACL reconstruction remain unclear. The aim of this study was to analyse the outcomes in women following ACL reconstruction and compare these outcomes with men.

MATERIAL AND METHODS

Retrospective study of a prospective database of patients treated with ACL reconstruction between January 2017 and December 2018. Outcome measures included Tegner activity scale, Lysholm scale, EVA scale, and IKDC evaluation form. Clinical significance was measured with minimally clinical important difference, and patient acceptable symptom state.

RESULTS

A total of 33 women were matched with 99 men. The mean follow-up was 36 months. Women showed significant improvement from preoperative PROs to the latest follow-up, with no differences between groups. In patients under 25 years old, there was less significant IKDC subjective score in women compared to men. There were no significant differences in frequency of patients achieving MCID and PASS in women compared with men.

CONCLUSIONS

At 3-year following 4-strand semitendinosus-gracilis anterior ligament reconstruction, women showed significant improvements in PROs, with no differences compared to men.

Outcome of 4-strand semitendinosus-gracilis anterior ligament reconstruction in women: A matched-cohort study

INTRODUCTION

Women carry out a greater risk of anterior cruciate ligament (ACL) rupture. However, outcomes following ACL reconstruction remain unclear. The aim of this study was to analyze the outcomes in women following ACL reconstruction and compare these outcomes with men.

MATERIAL AND METHODS

Retrospective study of a prospective database of patients treated with ACL reconstruction between January 2017 and December 2018. Outcome measures included Tegner activity scale, Lysholm scale, EVA scale, and IKDC evaluation form. Clinical significance was measured with minimally clinical important difference, and patient acceptable symptom state.

RESULTS

A total of 33 women were matched with 99 men. The mean follow-up was 36 months. Women showed significant improvement from preoperative PROs to the latest follow-up, with no differences between groups. In patients under 25 years old, there was less significant IKDC subjective score in women compared to men. There were no significant differences in frequency of patients achieving MCID and PASS in women compared with men.

CONCLUSIONS

At 3-year following 4-strand semitendinosus-gracilis anterior ligament reconstruction, women showed significant improvements in PROs, with no differences compared to men.

Hourglass-shaped grafts are superior to conventional grafts for restoring knee stability and graft force at knee flexion angle of 30° following anterior cruciate ligament reconstruction: A finite element analysis

Background: Anterior cruciate ligament reconstruction (ACLR) using a generally columnar graft is considered the gold standard for treating anterior cruciate ligament ruptures, but such grafts cannot replicate the geometry and mechanical properties of the native anterior cruciate ligament. Purpose: To evaluate the effectiveness of an innovative hourglass-shaped graft versus a traditional columnar graft for restoring joint stability and graft force, while avoiding notch impingement following anterior cruciate ligament reconstruction. Methods: Finite element models of a human knee were developed to simulate ① An intact state, ② anterior cruciate ligament reconstruction using columnar grafts with different diameters (7.5-12 mm in 0.5 mm increments), ③ anterior cruciate ligament reconstruction using columnar grafts with different Young's moduli (129.4, 168.0 and 362.2 MPa) and ④ anterior cruciate ligament reconstruction using hourglass-shaped grafts with different Young's moduli. The knee model was flexed to 30° and loaded with an anterior tibial load of 103 N, internal tibial moment of 7.5 Nm, and valgus tibial moment of 6.9 Nm. The risk of notch impingement, knee stability and graft forces were compared among the different groups. Results: This study found that columnar grafts could not simultaneously restore knee stability in different degree of freedoms (DOFs) and graft force to a level similar to that of the intact knee. The anterior tibial translation and graft force were restored to a near-normal condition when the internal tibial rotation was over-restrained and valgus tibial rotation was lax. A graft diameter of at least 10 mm was needed to restore knee stability and graft force to physiological levels, but such large grafts were found to be at high risk of notch impingement. In contrast, the hourglass-shaped graft was able to simultaneously restore both knee stability and graft force at knee flexion of 30° while also having a much lower risk of impingement. Conclusion: Under knee flexion angle of 30°, an hourglass-shaped graft was better able to restore joint stability and graft force to a near-physiological level than columnar grafts, while also reducing the risk of notch impingement.

The safety and effectiveness comparison of Delta Medical's PEEK interface screw and Endobutton and that of Smith & Nephew's in arthroscopic anterior cruciate ligament reconstruction: A multicenter prospective double-blind randomized controlled clinical trial

Background

To reduce the costs and financial burden in the ACLR treatment, we compare the early clinical outcomes and Magnetic Resonance Imaging (MRI) results of Delta Medical's PEEK (polyether ether ketone) interference screw and EndoButton with those of Smith & Nephew's PEEK interference screw and EndoButton in patients with arthroscopic anterior cruciate ligament reconstruction.

Methods

A total of 104 patients in five different medical centers were randomly allocated into two groups: 1: Delta Medical's PEEK interference screw and EndoButton (53 patients); 2: Smith & Nephew's PEEK interference screw and EndoButton (51 patients). The modified Lysholm knee score, the laxity examination, and clinical and functional range of motion were evaluated at 3 and 6 months postoperatively. The clinical effective rate was calculated and classified as excellent and good at 6 months postoperatively. MRI examinations were performed at 3 and 6 months postoperatively to determine the healing process. Computerized tomography (CT) was performed at 2 weeks and 3 months postoperatively to evaluate the complications.

Results

Significant improvements in knee function and functional scores were observed in both groups after surgery regardless of the fixation materials applied (P < 0.05). No differences were observed in the functional scores and range of motion. The assessments of Lysholm knee scores at 3 and 6 months produced no statistical differences (both P > 0.05). The clinical effective rate revealed no difference between the groups at 6 months postoperatively (non-inferiority analysis P = 0.0220). The differences of laxity examination between the groups were not statistically significant (Fisher's test, P = 0.6139, 0.2004, respectively). No significant differences in the functional range of motion were found at each follow-up time-point (P > 0.05). No major intra- or postoperative complications, such as infection, and vessel or nerve injury were observed.

Conclusions

Knee function and functional scores were improved after ACLR in both groups, regardless of the PEEK interference screw and EndoButton applied. The difference in functional scores and range of motion were not significant in groups 1 and 2. Delta Medical's PEEK interference screw and EndoButton had a non-inferiority effect compared to Smith & Nephew's PEEK interference screw and EndoButton. Delta Medical's PEEK interference screw and EndoButton were suitable for arthroscopic ACLR.

Bilateral changes in knee joint laxity during the first year after non-surgically treated anterior cruciate ligament injury

OBJECTIVES

Analyse changes in knee laxity between 3, 6, 12 and 24 months after non-surgically treated ACL injury and to analyse associations between knee laxity and knee function, self-reported knee stability, ACL-Return to Sport after Injury (ACL-RSI), fear and confidence at different timepoints during recovery.

DESIGN

Prospective cohort study.

PARTICIPANTS

125 patients (67 males, mean age 25.0 ± 7.0 years) with acute ACL injury.

MAIN OUTCOME

Laxity was measured using KT-1000 arthrometer. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). Confidence and fear were assessed with questions from the ACL-RSI scale. Subjectively knee stability was assessed using SANE.

RESULTS

Knee laxity increased bilaterally from 3 to 12 months, and in the non-involved knee from 3 to 24 months (p˂0.05), although mean change was below 1 mm. Side-to-side difference in knee laxity was correlated with IKDC-SKF (r = -0.283) and knee stability in rehabilitation/sport activities (r = -0.315) at 6 months, but not with confidence/fear.

CONCLUSION

Knee laxity increased bilaterally during the first year after non-surgically treated ACL injury, though, the mean change in knee laxity was below 1 mm and the clinical significance is unknown. Knee laxity was weakly associated with knee function and perceived knee stability.

LEVEL OF EVIDENCE

Level II TRIAL REGISTRATION: NCT02931084.

Graft Diameter Should Reflect the Size of the Native Anterior Cruciate Ligament (ACL) to Improve the Outcome of ACL Reconstruction: A Finite Element Analysis

The size of the anterior cruciate ligament (ACL) often varies between individuals, but such variation is not typically considered during ACL reconstruction (ACLR). This study aimed to explore how the size of the ACL affects the selection of a suitable graft diameter. A finite element model of a human knee was implanted with intact ACLs of different dimensions (0.95, 1 and 1.05 times the size of the original ACL) and with grafts of different diameters, to simulate ACLR (diameter 7.5–12 mm in 0.5 mm increments). The knee models were flexed to 30° and loaded with an anterior tibial load of 103 N, internal tibial moment of 7.5 Nm, and valgus tibial moment of 6.9 Nm. Knee kinematics (anterior tibial translation (ATT), internal tibial rotation (ITR) and valgus tibial rotation (VTR)) and ligament forces were recorded and compared among the different groups. The results showed that, compared with the intact knee, a graft diameter of 7.5 mm was found to increase the ATT and VTR, but reduce the graft force. Increasing the graft diameter reduced knee laxity and increased the graft force. A 10% increase in the size of the ACL corresponded to a 3 mm larger graft diameter required to restore knee stability and graft force after ACLR. It was concluded that the graft diameter should be selected according to the dimensions of the native ACL, for better restoration of knee functionality. This study may help to improve the clinical treatment of ACL ruptures.