Tibial Footprint Research Articles

Posterior Cruciate Ligament Reconstruction Using a Trans-septal Approach With Preserved Hamstrings Tibial Insertion

Posterior cruciate ligament reconstruction is a challenging procedure and requires a safe approach that provides a proper visualization of the tibial footprint while avoiding neurovascular damage and facilitating graft passage. Recent studies have shown that the preservation of the hamstring tibial attachment improves fixation and vascularization in the setting of anterior cruciate ligament reconstruction. This Technical Note reports an effective and reproducible arthroscopic single-bundle posterior cruciate ligament reconstruction through a trans-septal approach wit preserved hamstring tibial insertion.

Anterior Cruciate Ligament Reconstruction: 3-Incision Technique With Allograft Quad Tendon ACL Reconstruction

Background: Anterior cruciate ligament (ACL) ruptures are becoming more common in younger and older athletes. Approximately 250,000 ACL injuries occur each year, requiring the need for an effective and reproducible surgical technique. Indications: The 3-incision outside-in technique utilizes the donor quadriceps tendon, an extraordinarily strong graft, without damage from autogenous harvesting of patellar tendon or hamstrings. While some data suggest higher re-rupture risk with donor tissue, this is counterbalanced by avoiding secondary surgical site damage. Technique Description: The ruptured ACL is removed and the intercondylar notch is cleaned to visualize the anatomical ACL insertion site. Using the 3-tunnel technique a gaff is passed through the intercondylar notch, through a puncture hole (incision 1) and a rear entry guide hooked to its tip. The guide point is pulled into the knee and placed in posterior aspect of the anatomic footprint of the native ACL. Through incision 2, a guide pin is drilled to this point and overdrilled with a 10-mm drill. The edges of the hole in the intercodylar notch are smoothed with a currette. The tibial footprint is cleared, a tibial aiming guide placed. Through incision 3, a guide pin is placed and over drilled with a 10-mm drill followed by a Gore-Tex reamer to ensure no impingement would inhibit graft passage. The proximal bone of a quadriceps tendon graft is sized through a 10-mm sizer and compacted. Two holes are drilled to hold sutures for the proximal aspect of the femoral graft. The quadriceps tendon graft is sized to fit through a 9-mm tunnel and the free end whipped with a stitch before being passed from outside-in through the smoothed tunnels. The femoral bone block is tapped to have a press fit initially and then is fixed with a Milagro screw. The knee is cycled ten times to remove slack and the interference fit guide pin is placed on the anterior aspect of the graft, and fixed with the knee at 15° to 30° of flexion. Stability is tested with confirmation of no impingement, and then an extra-articular reconstruction with a semitendinosus allograft is performed. The extra articular reconstruction is placed at the point between Gerdy's tubercle and the fibular head, passed under the skin and the iliotibial band, and then inserted just anterior and superior to the ACL femoral drill hole. Results: Patient outcomes in our initial experience are comparable to our autogenous bone-tendon-bone (BTB) procedures without anterior knee pain. Return to sport is similar with autogenous procedures, with a delay of 6 to 12 months. In addition, there is a possibility for acceleration of healing with the addition of platelet-rich plasma and hyaluronic acid between 1 and 3 months postsurgery. We have insufficient data so far to determine if the re-rupture rate will decline compared with reported outcomes. Conclusion: The 3-incision technique with allograft quadriceps tendon for ACL reconstruction is a reproducible surgical technique that avoids harvest from the patient's own body. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Can patient anthropometry predict the anterior cruciate ligament footprint dimensions? - An MRI-based observational study on north Indian population

BackgroundAnterior Cruciate Ligament (ACL) reconstruction is one of the most common surgeries being currently done. As we usher into the era of Individualized Anatomic Reconstruction, it is very important to understand the native anatomy of ACL. We aimed to assess the ACL footprint dimensions in our patients and correlate it with anthropometric variables, which can help in preoperative decision making. MethodA total of 143 eligible patients with suspected ACL injury presented during the study period. Out of which 92 were included in the study. Data on patient's age, sex, height, weight and body mass index (BMI) was recorded. The length and area of both the tibial and femoral footprints were measured on MRI. The footprint dimensions were correlated with the recorded anthropometric data. ResultsThe ACL tibial footprint length and area, and femoral footprint length and area were found to be 13.3 ± 2.23 mm, 142.6 ± 26.16 mm2, 11.2 ± 1.97 mm, 125.8 ± 28.75 mm2 respectively. Footprint in males was significantly larger than females. A weak (ρ- 0.21 to 0.4) correlation with weight and moderate (ρ- 0.41 to 0.6) correlation with height was observed. Multivariate linear regression analysis yielded height to be the only significant predictor of footprint dimension from which predictive equations were drawn. ConclusionsHeight was found to be the most significant predictor of footprint dimensions in our patients. The predictive equations and graphs can aid in preoperative surgical decision making resulting in a more anatomical ACL reconstruction and improve the post-operative results.

Finite element analysis of anterior cruciate ligament reconstruction techniques: A comparison of the mechanical properties of all-inside fixation and traditional fixation.

The main purpose of this study was to explore the mechanical properties of the anterior cruciate ligament and its attachments following reconstruction with the all-inside technique after anterior cruciate ligament injury. Knee joint computed tomography data were collected from healthy volunteers, and knee joint models were created using Mimics software. A normal knee joint model, an all-inside reconstructed anterior cruciate ligament model, and a traditional reconstructed anterior cruciate ligament model were established. A tensile force of 134N and a bending moment of 5N/m were applied at the anterior aspect of the proximal tibia in these three models. The knee joint was subjected to external rotation, internal rotation, varus, valgus, flexion, and extension under this bending moment. The magnitude and distribution of stress on the ligament or graft and the magnitude and distribution of stress on the graft attachments were observed under different loading conditions. Under different external forces, the maximum stress on the ligament in the normal model fluctuated from 1.949 to 18.302MPa, with an uncertain distribution of maximum stress. The maximum stress on the graft in the all-inside reconstructed anterior cruciate ligament model fluctuated from 0.705 to 3.465MPa and was mainly distributed at the junction of the graft and the tibial footprint. In the traditional reconstructed anterior cruciate ligament model, the maximum stress on the graft fluctuated from 5.012 to 59.269MPa and was primarily distributed at the junction of the interference screw and the graft. The concentration of stress on the loop and plate in the all-inside reconstructed anterior cruciate ligament model fluctuated from 70.461 to 346.363MPa, with maximum stress distributed at the junction of the loop and the tibial surface. The maximum stress on the interference screw in the traditional reconstructed anterior cruciate ligament model fluctuated from 10.184 to 92.298MPa, with maximum stress primarily distributed at the end of the interference screw. Under different external forces, the graft used in all-inside anterior cruciate ligament reconstruction is subjected to fewer external forces than that used in traditional anterior cruciate ligament reconstruction, which may indicate a relatively stable mechanical environment. The strength of the loop and plate can theoretically tolerate daily knee joint movements of patients without injury.

POSTERIOR CRUCIATE LIGAMENT INJURIES MANAGED WITH INTERNAL BRACING

Poor availability of allografts in South Africa has led to an increased use of synthetic augmentation to stabilize knee joints in the treatment of knee dislocations. This study aims to evaluate multiligament knee injuries treated with a posterior cruciate ligament internal brace.The study included patients with knee dislocations who were treated with a PCL internal brace. The internal brace involved the insertion of a synthetic suture tape, which was drilled into the femoral and tibial footprint. Chronic injuries were excluded. Patient-reported outcome scores (PROMs), range of motion, stress X-Rays, and MRI scans were reviewed to assess outcomes. Acceptable outcomes were defined as a Lysholm score of 84 or more, with grade II laxity in no more than one ligament and a range of motion from full extension to 90° or more.The study included eight patients, with a median age of 42, of which five were female. None of the patients had knee flexion less than 90° or an extension deficit of more than 20°. PROMs indicated acceptable outcomes (EQ5D, Tegner Lysholm). Stress radiographs showed less than 7mm (Grade I) of posterior translation laxity in all patients. Four patients underwent MRI scans 1–2 years after the initial surgery, which revealed healing of the PCL in all patients. However, increased signal in a continuous ligament suggested only partial healing in two patients. Tunnel widening of 200% and 250% was noted around the tibial and femoral PCL footprints, respectively.All patients demonstrated stable knees and acceptable PROMs. Tunnel widening was observed in all patients who had MRI scans. Factors such as suspensory fixation, anisometric tunnel position, and the absence of PCL tear repair may have contributed to the tunnel widening.

Anatomic Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament reconstruction (ACLR) techniques have substantially evolved over the past several decades, driven by evidence that nonanatomic techniques increase the risk for instability, loss of motion, surgical failure, and posttraumatic osteoarthritis. Early techniques used transtibial femoral tunnel drilling, although improved understanding of the anatomy and biomechanics has led to independent femoral tunnel. Anatomic ACLR requires careful consideration of the native ACL dimensions and orientation. Although there is significant variation between patients, understanding of anatomic patterns allows for reliable identification of the ACL footprints and appropriate tunnel positioning, particularly in chronic injuries where the remanent ACL stump is degraded or absent. The femoral tunnel should be placed low and posterior on the lateral femoral condyle using the lateral intercondylar and bifurcate ridges as landmarks. The center of the tibial footprint can be determined by referencing the medial tibial spine and posterior border of anterior horn of lateral meniscus. Measurement of the dimensions of the native ACL and intercondylar notch is also critical for determining graft size and minimizing the risk of impingement, with a goal of reconstructing 50% to 80% of the tibial footprint area. Clinical outcome studies have demonstrated superior anteroposterior and rotatory knee stability with low surgical revision rates (reported between 3% and 5%). By adhering to the principles of anatomic ACLR, surgeons can produce an appropriately sized and located graft for the individual patient, thereby best restoring native knee kinematics and maximizing function. The aim of this infographic is to highlight essential features of anatomic ACLR techniques, which a focus on the native anatomy and surgical planning to achieve an anatomic ACLR.

Significant race and gender differences in anterior cruciate ligament tibial footprint location: a 3D-based analysis

BackgroundThe aim of the present study was to identify potential race- or gender-specific differences in anterior cruciate ligament (ACL) tibial footprint location from the tibia anatomical coordinate system (tACS) origin, investigate the distances from the tibial footprint to the anterior root of the lateral meniscus (ARLM) and the medial tibial spine (MTS), determine how reliable the ARLM and MTS can be in locating the ACL tibial footprint, and assess the risk of iatrogenic ARLM injuries caused by using reamers with various diameters (7–10 mm).Patients and methodsMagnetic resonance images of 91 Chinese and 91 Caucasian subjects were used for the reconstruction of three-dimensional (3D) tibial and ACL tibial footprint models. The anatomical coordinate system was applied to reflect the anatomical locations of scanned samples.ResultsThe average anteroposterior (A/P) tibial footprint location was 17.1 ± 2.3 mm and 20.0 ± 3.4 mm in Chinese and Caucasians, respectively (P < .001). The average mediolateral (M/L) tibial footprint location was 34.2 ± 2.4 mm and 37.4 ± 3.6 mm in Chinese and Caucasians, respectively (P < .001). The average difference between men and women was 2 mm in Chinese and 3.1 mm in Caucasians. The safe zone for tibial tunnel reaming to avoid ARLM injury was 2.2 mm and 1.9 mm away from the central tibial footprint in the Chinese and Caucasians, respectively. The probability of damaging the ARLM by using reamers with various diameters ranged from 0% for Chinese males with a 7 mm reamer to 30% in Caucasian females with a 10 mm reamer.ConclusionsThe significant race- and gender-specific differences in the ACL tibial footprint should be taken in consideration during anatomic ACL reconstruction. The ARLM and MTS are reliable intraoperative landmarks for identifying the tibial ACL footprint. Caucasians and females might be more prone to iatrogenic ARLM injury.Level of evidence: III, cohort study.Trial registration: This study has been approved by the ethical research committee of the General Hospital of Southern Theater Command of PLA under the code: [2019] No.10.

Correlation between femoral and tibial footprint of the anterior cruciate ligament using specific (CLASS) MRI novel sequences

Breaking the capacity barrier in intercalation-type anode materials for lithium-ion batteries while preserving other essential electrochemical properties remains a significant challenge. Here, using perovskite SrVO3 as a model, we demonstrate the feasibility of employing defect engineering to provide extra active sites for electrochemical reactions. Defective SrxVO3-δ samples with a unique amorphous-crystalline dual-phase structure are successfully prepared by regulating the nonstoichiometric Sr/V ratio and using a non-equilibrium solution combustion strategy to alleviate nucleation. The dual-phase SrxVO3-δ electrodes, which take advantage of both the high defect concentration advantage of amorphous and the high electrical/ionic conductivity of crystalline, give a high specific capacity of 508 mAh/g at a safe potential of 1.0 V vs. Li/Li+, showing a 40% increase over SrVO3 electrodes and outperforming most state-of-the-art intercalation-based anodes. In addition, when coupling with LiFePO4 cathode, the SrxVO3-δ electrodes can operate over 10,000 cycles with 91% capacity retention, overcoming the limited structural stability exhibited in typical defective electrodes. The study demonstrates the viability of modulating the crystallinity in intercalation-based anodes to enhance electrochemical performance and paves the way for the advancement of Li-ion battery technology.

Double-Bundle Anterior Cruciate Ligament Reconstruction With Primary Repair and Hamstring Autograft Augmentation

The optimal treatment of a ruptured anterior cruciate ligament (ACL) restores the patient’s native anatomy and biomechanics as close to normal as possible. The purpose of this technical note is to describe an ACL reconstruction technique in which a double-bundle concept is used, wherein one bundle contains repaired ACL tissue and the second bundle contains a hamstring autograft, and each bundle is tensioned independently. Even in chronic cases, this technique allows for incorporation of the native ACL because, more often than not, there is sufficient tissue of good quality available for repair of one bundle. By augmenting the ACL repair with an autograft sized to the fit the individual anatomy, the patient’s ACL tibial footprint can be closely restored to normal, and the potential benefits of tissue preservation are combined with the biomechanical strengths of an autograft double-bundle ACL reconstruction.

“Over-the-Top” Anterior Cruciate Ligament Reconstruction Associated With a Lateral Extra-Articular Tenodesis in Children

Anterior cruciate ligament (ACL) tears are one of the most frequent injuries in growing children, and they are often associated with other injuries such as meniscal and chondral injuries. In the past, treatment of ACL tears in growing patients relied on activity modification and bracing. However, surgical treatment has prevailed over conservative treatment in recent years. A surgical technique is presented for ACL reconstruction using an “over-the-top” technique associated with a lateral extra-articular tenodesis procedure in children. An extra-articular lateral tenodesis is done first. The gracilis and semitendinous tendons are then extracted using a tenotome without releasing their distal desinsertions. The tibial guide is then centered over the ACL tibial footprint under arthroscopic vision and an image intensifier, proximal to the physis. Then, a Kocher-type forceps is used to pass a suture “over the top” from the posterolateral window to the tibial tunnel. The double-bundle graft and iliotibial tract graft are fixed within the tunnel in full extension and neutral rotation with an interference screw.

Anterior Cruciate Ligament Reconstruction With Transtibial Medial Meniscus Root Repair

Background: The incidence of anterior cruciate ligament (ACL) injuries has rapidly increased. Patients with ACL injuries frequently present with concomitant meniscal pathologies. Posterior medial meniscal root tears (PMMR) are less commonly seen with acute ACL injuries as compared with lateral tears and are often degenerative in nature or more rarely in an acute setting. Clinical studies have demonstrated medial meniscal deficiency to be a significant risk factor for graft failure and poor postoperative clinical outcomes. As such, given its demonstrated efficacy, there has been growing interest in transtibial meniscal repair mechanisms in combination with an ACL reconstruction as a potential solution to this challenging pathology. Indication: Patients are indicated for surgery when presenting with symptomatic ACL deficiency verified on provocative testing and advanced imaging and objective insufficiency of the medial meniscal root. Contraindications for this procedure include advanced osteoarthritis (Kellgren–Lawrence grade ≥3) on weight-bearing x-rays, age &lt;50 years, and body mass index (BMI) &gt; 30 as well as poor-quality meniscal tissue and unrepairable chondral defects. Technique Description: The ACL stump is debrided and a burr hole is created. A femoral aiming guide is used to drill the femoral tunnel. Following medial collateral ligament (MCL) release, a healing bony bed is prepared with a curette and shaver at the anatomic tibial footprint. An aiming device is then used through the anterior medial portal to create 2 transosseous tibial tunnels. A vertical mattress suture and simple suture are placed through the meniscal root, shuttled through the posterior and anterior transosseous tunnels, respectively. The tibial ACL tunnel is placed using a standard guide to avoid tunnel convergence with the root tunnels and prevent graft tunnel mismatch. After graft passage, interference screws are inserted while maintaining graft tension. The sutures are then tied over a cortical button over the tibia. Results: Within 2 years postoperatively, patients are expected to have improved overall knee-specific quality of life, reduced pain, and a successful return to activities with low rates of graft failure. Discussion/Conclusion: Recent advancements in our understanding of the relationship between the medial meniscus and the ACL should prompt surgeons to continue considering such combined treatments in indicated patients. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Anatomical and Biomechanical Characteristics of the Anterolateral Ligament: A Descriptive Korean Cadaveric Study Using a Triaxial Accelerometer.

Background and Objectives: The anterolateral ligament (ALL) could be the potential anatomical structure responsible for rotational instability after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to investigate the anatomical and biomechanical characteristics of the ALL in Korean cadaveric knee joints. Materials and Methods: Twenty fresh-frozen cadaveric knees were dissected and tested. Femoral and tibial footprints of the ALL were recorded. Pivot shift and Lachman tests were measured with KiRA. Results: The prevalence of ALL was 100%. The average distance of the tibial footprint to the tip of the fibular head was 19.85 ± 3.41 mm; from the tibial footprint to Gerdy's tubercle (GT) was 18.3 ± 4.19 mm; from the femoral footprint to the lateral femoral epicondyle was 10.25 ± 2.97 mm. ALL's footprint distance was the longest at 30° of flexion (47.83 ± 8.05 mm, p < 0.01) in a knee with intact ALL-ACL and neutral rotation. During internal rotation, the footprint distance was the longest at 30° of flexion (50.05 ± 8.88 mm, p < 0.01). Internal rotation produced a significant increase at all three angles after ACL-ALL were transected (p = 0.022), where the footprint distance was the longest at 30° of flexion (52.05 ± 7.60 mm). No significant difference was observed in KiRA measurements between intact ALL-ACL and ALL-transected knees for pivot shift and Lachman tests. However, ACL-ALL-transected knees showed significant differences compared to the intact ALL-ACL and ALL-transected knees (p < 0.01). Conclusions: The ALL was identified as a distinct ligament structure with a 100% prevalence in this cadaveric study. The ALL plays a protective role in internal rotational stability. An isolated ALL transection did not significantly affect the ALL footprint distances or functional stability tests. Therefore, the ALL is thought to act as a secondary supportive stabilizer for rotational stability of the knee joint in conjunction with the ACL.

Surgical technique: posterior cruciate ligament (PCL) reconstruction using double posteromedial arthroscopic portals

The posterior cruciate ligament (PCL) reconstruction is a technically demanding surgical procedure that requires optimal identification of both the femoral and the tibial anatomical footprints. To aid the tibial tunnel placement and many authors recommend creating a posteromedial (PM) portal. The further addition of a second PM portal, which could be used as a “working portal”, may further allow a more straightforward reconstruction by improving the identification of the anatomical footprint, the clearing of the stump, and the graft passage.

Surgically adjust tibial tunnel in anatomical anterior cruciate ligament single-bundle reconstruction: A time-zero biomechanical study in vitro.

The anatomical positioning of the graft during anterior cruciate ligament reconstruction (ACLR) is of great significance for restoring normal knee kinematics and preventing early joint degeneration. Therefore, the adjustment of the mispositioned guide pin becomes extremely important. Our research aims to test the time-zero biomechanical properties in adjusting inaccurate guide pins to the center of the tibial footprint in anatomical anterior cruciate ligament single-bundle reconstruction. Porcine tibias and bovine extensor tendons were used to simulate a transtibial ACL reconstruction in vitro. Load-to failure testing was carried out in 4 groups: control group (n = 45): the guide pin was drilled at the center of the ACL footprint; group I, group II and group III (n = 45, respectively): the guide pin was respectively drilled 1mm, 2mm and 3mm away from the center of the ACL footprint. In the experimental groups, a small tunnel with a 4.5mm reamer is made and the guide pin is shifted to the center of the footprint. All the reamed tibias were scanned by CT to measure the area of the tunnel in the footprint, and time-zero biomechanical properties were recorded. All graft-tibia complexes failed because the grafts slipped past the interference screws. Compare to control group, the ultimate load, yield load, and tunnel exit area in group III decreased significantly (p < 0.05). Regarding to the ultimate load, yield load, tensile stiffness, twisting force and tunnel exit area, t-test showed no significant differences between control group and group I, group II respectively (p > 0.05). Pearson test showed that tunnel exit area was negatively correlated with other characteristics (p < 0.05). Surgical adjustment of the guide pin to the center of the tibial footprint may have significant influence in time-zero biomechanical properties in anatomical anterior cruciate ligament single-bundle reconstruction when the adjusted tibial tunnel was significantly enlarged compare to the standard tibial tunnel.

Morphometry of the Tibial Footprint of the Anterior Cruciate Ligament in Punjabi Population

Background: The anterior cruciate ligament (ACL) is responsible for knee joint stability during all possible movements. The purpose of our present study was to estimate normal values of the position and dimensions of the tibial attachment of ACL for its successful reconstruction. Methodology: A sagittal magnetic resonance imaging (MRI) sample of the knee joint of 120 patients (58 men and 62 women) of 18–50 years of age was reviewed. Results: Anterior end of the tibial footprint was located at a mean of 14.92 mm ± 3.42 mm from the anterior end of the tibial plateau. The posterior end of the tibial footprint was located with a mean of 28.76 mm (±7.02) from the anterior end of the tibial plateau. The mean tibial footprint sagittal length was 14.56 mm ± 0.66 mm. The mean anterior cruciate sagittal center was located at 42.62% ±2.99% of the anteroposterior length of the tibial plateau. The present study will provide the baseline morphometric data for the position and size of the tibial footprint of the ACL on MRI in Punjab. Mean roof angle in the present study was 35.16° (±3.49°). Mean ACL-inclination angle was 50.13°(±4.56°). Mean ACL-Bluemensaat angle in the present study was 4.23°(±2.87°). Conclusion: Present study can help surgeons to ascertain the positioning of the tibial tunnel in routine ACL reconstruction as well as revised ACL reconstruction surgeries.

A deep learning approach for anterior cruciate ligament rupture localization on knee MR images.

Purpose: To develop and evaluate a deep learning-based method to localize and classify anterior cruciate ligament (ACL) ruptures on knee MR images by using arthroscopy as the reference standard. Methods: We proposed a fully automated ACL rupture localization system to localize and classify ACL ruptures. The classification of ACL ruptures was based on the projection coordinates of the ACL rupture point on the line connecting the center coordinates of the femoral and tibial footprints. The line was divided into three equal parts and the position of the projection coordinates indicated the classification of the ACL ruptures (femoral side, middle and tibial side). In total, 85 patients (mean age: 27; male: 56) who underwent ACL reconstruction surgery under arthroscopy were included. Three clinical readers evaluated the datasets separately and their diagnostic performances were compared with those of the model. The performance metrics included the accuracy, error rate, sensitivity, specificity, precision, and F1-score. A one-way ANOVA was used to evaluate the performance of the convolutional neural networks (CNNs) and clinical readers. Intraclass correlation coefficients (ICC) were used to assess interobserver agreement between the clinical readers. Results: The accuracy of ACL localization was 3.77 ± 2.74 and 4.68 ± 3.92 (mm) for three-dimensional (3D) and two-dimensional (2D) CNNs, respectively. There was no significant difference in the ACL rupture location performance between the 3D and 2D CNNs or among the clinical readers (Accuracy, p < 0.01). The 3D CNNs performed best among the five evaluators in classifying the femoral side (sensitivity of 0.86 and specificity of 0.79), middle side (sensitivity of 0.71 and specificity of 0.84) and tibial side ACL rupture (sensitivity of 0.71 and specificity of 0.99), and the overall accuracy for sides classifying of ACL rupture achieved 0.79. Conclusion: The proposed deep learning-based model achieved high diagnostic performances in locating and classifying ACL fractures on knee MR images.

Application of CT-MRI Fusion-Based Three-Dimensional Reconstruction Technique in the Anatomic Study of Posterior Cruciate Ligament.

During PCL reconstruction surgery, precise and personalized positioning of the graft tunnel is very important. In order to obtain patient-specific anatomical data, we established a three-dimensional knee joint fusion model to provide a unified imaging strategy, as well as anatomical information, for individualized and accurate posterior cruciate ligament (PCL) reconstruction. This is an exploration study. From January 2019 to January 2020, 20 healthy adults randomly were enrolled and assessed via CT and MRI imaging. A three-dimensional fusion model of the knee joint was generated using the modified MIMIMICS and image fusion software. On the fused image, the areas of the femoral and tibial PCL footprint of both knees were measured. The anatomical center of the PCL footprint was measured at the femoral and tibial ends. The relevant bony landmarks surrounding the PCL femoral and tibial attachment were also measured. Paired t-tests were employed for all statistical analyzes, and p < 0.05 was considered as statistically significant. All 20 subjects achieved successful image fusion modeling and measurement, with an average duration of 12h. The lengths of the LF1-LF3 were 32.1 ± 1.8, 6.8 ± 2.5, and 23.3 ± 2.1 mm, respectively. The lengths of the LT1-LT3 were 37.3 ± 3.3, 45.6 ± 5.3, and 6.0 ± 1.2 mm, respectively. The distances between the tibial PCL center of the left knee to the medial groove, champagne-glass drop-off, and the apex of the medial intercondylar were 8.4 ± 2.4, 9.2 ± 1.8, and 15.3 ± 1.4 mm, respectively, and the corresponding distances from the right knee were 8.0 ± 2.0, 9.4 ± 2.2, and 16.1 ± 1.8 mm, respectively. We observed no difference between the bilateral sides, in terms of the distance from the PCL center to the PCL attachment-related landmark, under arthroscopic guidance. The area of the femoral and tibial PCL footprints on the left knee were 115.3 ± 33.5 and 146.6 ± 24.4 mm2 , respectively, and the corresponding areas on the right knee were 121.8 ± 35.6 and 142.8 ± 19.5 mm2 , respectively. There was no difference between the bilateral sides in terms of the PCL footprint areas. In the fusion image, the PCL attachment center and relevant bony landmarks which can be easily identified under arthroscopy can be accurately measured. The model can also obtain personalized anatomical data of the PCL on the unaffected side of the patient, which can guide clinical PCL reconstruction.

Age-Related Posterior Cruciate Ligament Surgical Anatomy in a Skeletally Immature Population: An MRI Study

Background: Magnetic resonance imaging (MRI) analysis of the developmental morphology of the anterior cruciate ligament (ACL) in pediatric and adult patients has led to the identification of anatomical risk factors for injury and optimization of surgical reconstruction. Similar work regarding the pediatric posterior cruciate ligament (PCL) is limited. The aim of this study was to describe age-dependent changes in ligamentous and osseous anatomy of the pediatric PCL by comparison of MRI measurements. Methods: Sixty randomly selected patients were categorized into three skeletal age groups (ages 7-9 years, 10-12 years, and 13-15 years) with 20 patients in each. Twelve anatomical dimensions were measured on MRI by two independent reviewers. Pairwise comparisons were conducted between the youngest and intermediate, as well as the intermediate and oldest age groups. Results: Statistically significant growth in femoral physis width (p&lt;0.001), tibial physis width (p&lt;0.001), and medial femoral condyle (MFC) width (p&lt;0.001) and height (p&lt;0.001) was found across all skeletal age groups. Growth in femoral PCL height (p=0.02), femoral PCL footprint to femoral physis height (p=0.004), tibial PCL insertion width (p&lt;0.001), tibial PCL footprint to tibial physis distance (p&lt;0.001), and tibial epiphysis height (p=0.003) and width (p&lt;0.001) was only statistically significant between the youngest and intermediate groups. Only MFC height (p=0.03) and width (p=0.001), femoral PCL height (p=0.05), and tibial physis width (p=0.02) were significantly larger in the oldest compared to the intermediate group. Intrarater reliability for all measurements was excellent; interrater reliability was variable. Conclusions: Morphological changes of the pediatric PCL and associated surgical anatomy vary by skeletal age throughout childhood and adolescence. Differences were most evident between preadolescents with open physes compared to adolescents with closing physes, who demonstrated slowed or plateaued growth in most dimensions. The femoral physis was located proximal to the origin of the PCL in all age groups. The relationship of the distal PCL footprint to posterior proximal tibial physis varied. Young children (7-9 years) had footprints significantly more distal to the tibial physis, thus, native PCL reconstruction in this age group may be possible. Anatomical reconstruction in adolescents poses greater risk as the PCL footprint is closest to the tibial physis. Analysis of age-dependent transformations of the PCL and surrounding anatomy may inform surgical planning and enhance understanding of physeal location in this active population.

Patellar tendon rupture as a first presentation for undiagnosed primary hyperparathyroidism

Introduction: patellar tendon rupture is usually traumatic in origin; however, spontaneous or atraumatic rupture is uncommon and often signify underlying pathological processes involving the tendon substance. One of these pathological processes is primary hyperparathyroidism.Case Presentation: In this case report we present a unique case of a patient not diagnosed previously with hyperparathyroidism. The patient’s initial presentation was atraumatic knee pain and knee extension weakness, imaging studies showed complete avulsion of the patellar tendon from its tibial footprint. Another clinical finding was an index finger swelling, which, after laboratory and imaging studies of the parathyroid gland, turned out to be brown tumor of undiagnosed primary hyperparathyroidism. The patient underwent excision of the parathyroid adenoma, and repair of the patellar tendon using semitendinosus tendon graft and intraosseous tibial anchors at the footprint. Patient regained pain-free and good movement of her knee. Conclusion: Atraumatic patellar tendon rupture, especially in the absence of renal impairments should raise the suspicion of pathological process involving the tendon substance, this should alert the orthopedic surgeon to look for secondary causes of degeneration of the tendon substance, of which hyperparathyroidism is an important differential diagnosis.

Poster 218: Biomechanical Function of the Lateral Meniscus Posterior Root and Meniscofemoral Ligaments: A Computational Study

Objectives:Tear of the posterior root of the lateral meniscus (LMPR[ICP1] ) is commonly associated with ACL rupture. Surgical repair of the LMPR is indicated to stabilize the knee and protect the knee from progressive osteoarthritis. However, this surgery may be technically challenging or the location of the tear may not support anatomic repair to the tibial footprint. Even in the setting of a torn LMPR, a common intraoperative observation is that the anterior (Humphrey) meniscofemoral ligament (aMFL) remains intact. We denote this constellation as the HIRO lesion (Humphrey Intact, Root Out). This studied utilized a computational model of the knee to understand load sharing between the ACL, LMPR, and the MFLs in response to pivoting maneuvers. We hypothesized that (1) lateral compartment ATT would be greater in the knee with a combined deficiency of the LMPR and MFLs compared to intact MFLs (i.e. HIRO lesion, Figure 1) and that (2) the ACL force would be lower in the presence of a HIRO lesion as compared to combined LMPR and MFL injury.Methods:A previously developed computational model of the native tibiofemoral joint was utilized. The model including geometries of the tibia, femur, cartilage and menisci incorporating average properties for ligaments, capsule, meniscal attachments, and MFLs. Multiplanar torques simulating a pivoting maneuver were applied to the computational model at 30° of flexion, consisting of valgus (8 Nm), and internal rotation (4 Nm) to assess the impact of simulated sectioning of the ACL, LMPR, and MFLs. Lateral compartment anterior tibial translation and force carried by the ACL, LMPR, and each MFL were assessed at the peak applied pivoting loads.Results:With all structures intact, peak applied pivoting loads resulted in lateral compartment anterior tibial translation of 10.4 mm. With sequential ligament sectioning, lateral compartment anterior translation increased by 0.5 mm with LMPR deficiency; 5.8 mm with ACL deficiency; 8.5 mm with combined LMPR and ACL deficiency; and 8.9 mm with combined LMPR, ACL, and aMFL deficiency. Force carried by the ACL was 100 N at baseline; this increased by 12 N with LMPR deficiency and by an additional 1 N with combined sectioning of the LMPR and both MFLs. The intact LMPR saw an increase in force by 18 N with ACL deficiency from baseline. The aMFL force increased by 12 N with LMPR sectioning and by an additional 4 N with combined LMPR and ACL deficiency. The posterior MFL did not see force with simulated pivot shift testing at 30° knee flexion.Conclusions:A HIRO lesion results in a 14% increase in lateral compartment ATT (versus ACL deficiency alone) compared to a 16% increase when both the LMPR and MFLs are sectioned. While the ACL saw 12% increased force with a HIRO lesion, there was a 1 N increase in ACL force with combined LMPR and MFL sectioning. The load-bearing role of the aMFL was more pronounced with combined ACL and LMPR tear compared to LMPR tear with intact ACL. The biomechanical model confirms that, during a pivot shift, the LMPR has a primary role in lateral compartment ATT and load-sharing with the ACL compared to the aMFL. Surgeons should attempt to repair the LMPR with ACL reconstruction.Figure 1.Arthroscopic image demonstrating Humphrey Intact Root Out (HIRO) lesion in a 34-year-old male patient with combined anterior cruciate ligament/ lateral meniscus posterior root (LMPR) injury. The lateral meniscus (LM) body is disrupted from the LMPR footprint as a consequence of a radial tear (note the gap in the tissue continuity from LM body to LMPR). The anterior meniscofemoral ligament of Humphrey is visible with robust attachment to LM body connecting to the medial femoral condyle. LFC = Lateral femoral condyle (visualized in figure 1B).Table 1.Lateral compartment ATT and forces subjected to ACL, LMPR, aMFL and pMFL as outputs of a computational cadaveric knee model subjected to peak applied pivoting loads at 30° of flexion, consisting of valgus (8 Nm) and internal rotation (4 Nm).