Anterior Horn Of Lateral Meniscus Research Articles

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.

A Rare Case: Ganglion Cysts in the Proximal Tibiofibular Joint Causes Lateral Side Knee Pain: A Case Report

Introduction: Proximal tibiofibular joint (PTFJ) ganglion cysts are very rare. The pathophysiology remains unclear. Lateral knee pain was present in dominant case, and some cases accompanied with common peroneal nerve symptoms. In cases of chronic trauma, it is sometimes confused with proximal tibiofibular joint instability. Thorough examination and investigations such as MRI are highly recommended. There is no consensus of management, but some studies indication that excision of the ganglion associated with low recurrences number. Method: We report a case of 28 yeara-old woman, with a chief complain of pain on the lateral side of her right knee. Pain increasing on one last year. She had a trauma on her knee in 5 years ago. She was diagnosis with Lateral Instability of her knee by a previous surgeon and refer to our clinic for second opinion. In physical exam we found, tenderness around fibula head, Lachman, McMurray, Lelli’s test was negative. Shuck test was not evident.. MRI was done and showing partial tear of anterior horn of lateral meniscus and partial tear of anterior proximal tibia fibula ligament also a fluid collection around the fibular head. We planned to repair the meniscus through arthroscopic and stabilize the Proximal tibiofibular joint with open surgery. Results: Standard arthroscopic surgery was performed. Tear anterior horn meniscus was repair using inside out technique. In open surgery we found the anterior proximal tibiofibular ligament quite stable, and also we found a ganglion cyst around the PTFJ. We decided to leave the anterior PTFJ ligament, and excise the ganglion until its sac and follow up the case forward. Conclusion: Symptoms of pain caused by ganglion cysts in PTFJ, although rarely, can be very disturbing. The history of chronic trauma obscures this case with instability condition. There for careful diagnosis is required. Excision of the ganglion into the sac is the treatment of choice because of the very low recurrence rate. The complex anatomical composition of the lateral side of the knee can cause pain to arise from various components. The presence of PTFJ ganglion cysts should not be ignored

Injury Prevention Effect of MRI Imaging Technology in Physical Education and Sports Training.

In order to solve the problem of observing and analyzing the clinical value of MRI diagnosis in patients with knee sports injury and guiding clinical targeted treatment, the author proposed a sports injury prevention method in sports training teaching based on MRI image observation. This method retrospectively analyzed the imaging data of 101 patients with knee joint MRI examination due to osteoarthritis, sports injury and synovitis in joint surgery, and arthroscopic exclusion of true meniscus tear, MR multisequence and multiplane scans were performed to observe the anatomical features of TGL and MFL images and the occurrence rate of the lateral meniscus “false tear sign,” and the χ2 test was used to compare the occurrence rate of “pseudo-tear sign” between genders and sides. Experimental results show that the incidence of TGL on MRI was about 67.3% (68/101), and the incidence of “pseudo-tear sign” in the anterior horn of the lateral meniscus caused by TGL was 2.9% (2/68). The overall appearance rate of MFL on MRI was 91.1% (92/101), the appearance rate of plate anterior ligament (HL) was 13.9% (14/101), and the occurrence rate of “pseudo-tear sign” in the posterior horn of the lateral meniscus caused by HL was 7.1% (1/14). The occurrence rate of the posterior ligament (WL) was 77.2% (78/101), and the incidence of “pseudo-tear sign” in the posterior horn was 20.5% (16/78). According to the shape and course of TGL and MFL on MRI, and the direction and position of the lateral meniscus pseudotear, combined with MRI sagittal plane and coronal plane observation, it can effectively identify the true and false attributes of lateral meniscus anterior and posterior horn tears, thereby reducing unnecessary surgical treatment.

Variances of the intraarticular landmarks for anterior cruciate ligament tibial footprint: Tibial eminencies have less variability than lateral meniscus on sagittal magnetic resonance scans

Objective: The purpose of this study was to analyze the sagittal plane variations of intraarticular landmarks for single bundle anterior cruciate ligament (ACL) reconstruction including lateral meniscus, medial and lateral tibial eminencies. Methods: T2 weighted sagittal magnetic resonance (MR) scans of 80 skeletally mature patients aged between 18 to 60 years and without any sign of ligament and meniscal injuries were viewed. Midpoint of ACL, most posterior aspect of anterior horn of lateral meniscus (LMAH), tip of medial eminence (ME) and lateral eminence (LE) were identified on widest antero-posterior (A-P) distance of tibial plateau according to of Staubli-Rausching method and variances were compared. Results: Mean location of center of tibial footprint of ACL at sagittal plane was found as 38.0±4.2% (range, 29-51%) on A-P distance of tibial plateau. Location of posterior border of LMAH, ME and LE were 38.0±12.4% (range, 21-62%), 52.3±4.2% (range, 41- 60%) and 59.5±4.4% (range, 51- 69%), respectively. Difference between the variances of ACL midpoint and LMAH was large enough to be statistically significant (p=<.001) with a large effect size (f=0.59), however differences between the variances of ACL midpoint and bony landmarks were not significant (ME, p=.65; LE, p=.33). Intra and interobserver agreement for measurement of all parameters were detected as moderate to good. Conclusion: There was no constant relationship between ACL midpoint and posterior border of LMAH on sagittal plane MR images. Difference of variances between ACL midpoint and ME and LE were significantly lower than of variances of LMAH.

Effect of Tibial Tunnel Placement Using the Lateral Meniscus as a Landmark on Clinical Outcomes of Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: It remains unclear if use of the lateral meniscus anterior horn (LMAH) as a landmark will produce consistent tunnel positions in the anteroposterior (AP) distance across the tibial plateau. Purpose: To evaluate the AP location of anterior cruciate ligament (ACL) reconstruction tibial tunnels utilizing the LMAH as an intra-articular landmark and to examine how tunnel placement affects knee stability and clinical outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective review was conducted of 98 patients who underwent primary ACL reconstruction with quadrupled hamstring tendon autografts between March 2013 and June 2017. Patients with unilateral ACL injuries and a minimum follow-up of 2 years were included in the study. All guide pins for the tibial tunnel were placed using the posterior border of the LMAH as an intra-articular landmark. Guide pins were evaluated with the Bernard-Hertel grid in the femur and the Stäubli-Rauschning method in the tibia. Patients were divided by the radiographic location of the articular entry point of the guide pin with relation to the anterior 40% of the tibial plateau. Outcomes were evaluated by the Marx Activity Scale and International Knee Documentation Committee (IKDC) form. Anterior knee laxity was evaluated using a KT-1000 arthrometer and graded with the objective portion of the IKDC form. Rotational stability was evaluated using the pivot-shift test. Results: A total of 60 patients were available for follow-up at a mean 28.6 months. The overall percentage of AP placement of the tibial tunnel was 39.3% ± 3.8% (mean ± SD; range, 31%-47%). Side-to-side difference of anterior knee laxity was significantly lower in the anterior group than the posterior group (1.2 ± 1.1 mm vs 2.5 ± 1.3 mm; P < .001; r = 0.51). The percentage of AP placement of the tibial tunnel demonstrated a positive medium correlation with side-to-side difference of anterior knee laxity as measured by a KT-1000 arthrometer (r = 0.430; P < .001). The anterior group reported significantly better distribution of IKDC grading as compared with the posterior group (26 grade A and 6 grade B vs 15 grade A and 13 grade B; P = .043; V = 0.297). The pivot-shift test results and outcome scores showed no significant differences between the groups. Conclusion: Using the posterior border of the LMAH as an intraoperative landmark yields a wide range of tibial tunnel locations along the tibial plateau, with anterior placement of the tibial tunnel leading toward improved anterior knee stability.

A PROSPECTIVE CROSS-SECTIONAL STUDY ON MRI EVALUATION OF INTERNAL DERANGEMENTS OF THE KNEE JOINT

Introduction: Internal derangements of knee joint constitute a major source of morbidity in patients attending orthopaedic outpatients department of our hospital. It includes a group of disorders due to disruption of normal functioning of ligaments and menisci of knee joint leading to persistent or intermittent signs and symptoms such as pain, instability, or abnormal mobility of the knee. MRI would be a noninvasive, nonoperator dependent effective modality for early detection of these pathologies and has very high negative predictive value.&#x0D; Material and Methods: The study was carried out over a period of one year from April 2018 to April 2019. Fifty patients with clinically suspected internal derangement of knee were included in this prospective study. They were evaluated with detailed clinical history and clinical examinations and were subsequently subjected to imaging of knee using 1.5 T HDxt 8 Channel GE MRI machine.&#x0D; Results: ACL was the commonest ligament to be injured with partial tear being more common than complete tear. MCL was the commonest ligament to be torn in association with ACL. Indirect signs of ACL injury were evaluated and helped to corroborate the tears. Meniscal injury was common in medial meniscus and predominantly involved the posterior horn. In lateral meniscus anterior horn was involved more than posterior horn. In both the meniscus horizontal tear was the most common. Certain pattern of associations of injuries was found such as ACL tear with posterolateral corner injury. &#x0D; Interpretation and Conclusion: MR is an excellent tool for evaluation of ligaments, menisci and osseous structures of knee joint. Various clinical tests and appropriate clinical history complements MR examination. Similarly MR imaging of knee complements therapeutic arthroscopies and would greatly reduce the need of diagnostic arthroscopies. Thus MR is a non-invasive, painless and morbidity-free modality for accurate preoperative assessment that is well accepted by patients.

Biomechanical study of medial meniscus after posterior horn injury: a finite element analysis

We established an effective finite element model of knee joint for observation of stress and displacement of meniscus related changes after medial meniscus injury. Different types of medial meniscus injury can lead to varied meniscus stress and displacement changes. Stress and displacement concentration were found in fissure tip of meniscus tear compared to normal meniscus. The posterior horn injury of medial meniscus may initiate combined injury of medial meniscus posterior horn (MMPH) and that of medial meniscus body, and combined injury of MMPH and that of lateral meniscus anterior horn; fissure expansions regarding horizontal fissure, longitudinal fissure and grip-shaped fissure of MMPH were spotted.

Anatomical and finite element analysis of anterior cruciate ligament reconstruction within biomechanical insertion

To provide new concepts of anterior cruciate ligament (ACL) reconstruction by anatomical gross observation of ACL tibial insertion and finite element analysis of distribution of ACL mechanical insertion. In the anatomical study, ten fresh adult cadaveric knees were dissected, including 6 males and 4 females, all knees were generally observed through standard medial parapatellar approaches, paying attention to the close anatomical relationship of tibial insertion and anterior horn of lateral meniscus, and ACL was exposed and gradually removed from the inside. The shape of tibial insertion of ACL was observed and recorded, and anterior-posterior diameters and left-right diameters of tibial insertion were measured with vernier caliper. For the study of finite element analysis, three-dimensional thin-layer magnetic resonance imaging of normal knee joint was used to establish knee joint model. Three-dimensional reconstruction software MIMICS and finite element analysis software ANSYS were used to establish knee joint model, subsequently, clinical physical examination Lachman test and pivot-shift test were simulated to observe the force distribution of ACL tibial insertion and femoral insertion. The ACL tibial mechanical insertion was rather flat and long similar as an arc shape without a clear separation between anterior medial bundle (AMB) and posterolateral bundle (PLB) in gross observation. The dense fibers lies belonged to the medial intercondylar ridge and ended up anterior with the osseous landmark of anterior ridge. Its average anterior-posterior diameter was (13.8±2.0) mm, the average left-right diameter of midsubstance was (5.3±0.6) mm, and the average left-right diameter of anterior margin was (11.5±1.2) mm. The finite element analysis showed that distribution on the femoral side was oval shape mainly below the residents' ridge, while the tibial side was rather flat mainly along the medial intercondylar ridge, which was consistent with the anatomical observation. The biomechanical characteristics of ACL attachments were verified theoretically. Anatomical study and finite element analysis have confirmed the flat arc shape of ACL tibial insertion. The ideal reconstruction technique of ACL should be based on its biomechanical insertion. Based on anatomical study and biomechanical analysis, we have proposed the idea of ACL biomechanical insertion reconstruction (BIR) and established a surgical model with oval femoral tunnel and rounded-rectangle tibial tunnel.

Systematic review of bone tunnel placement in anterior cruciate ligament near-isometric reconstruction

Objective To identify the optimal placement of bone tunnel during near-isometric anterior cruciate ligament reconstruction (ACLR), and its dimensional relationship with knee anatomic structure after summarizing published researches. Methods PubMed, Embase, and CNKI were screened for Chinese or English articles on clinical studies, cadaveric studies of knee and reviews on bone tunnel placement in anterior cruciate ligament near-isometric reconstruction and isometry of native anatomic fibers. Related articles were extracted and systematically reviewed. Results A total of 21 articles were finally included after screening. This systematic review found that most of the literatures were cadaveric studies, among which three dimensional imaging techniques, combined with cadaveric studies, were commonly used as a method of determining the length change between spots on the tibial plateau and lateral condyle of femur in recent years. There were 3 case series and 1 prospective cohort study. On the side of lateral condyle of femur, Blumensaat's line, lateral intercondylar ridge and insertion of intact anterior cruciate ligament were commonly used as reference to describe the near isometric area, while on the side of tibial plateau, the anterior horn of lateral meniscus were used as reference for reconstruction. The bone tunnel on tibial side was ignored compared with the femoral side when considering the isometry of reconstruction. There were overlaps among areas of bone tunnel placement found by different studies in near-isometric reconstruction. Not all native anterior cruciate ligament fibers were near-isometric. Conclusion The present study found that the area of femoral bone tunnel of anterior cruciate ligament near-isometric reconstruction were near the anterior part of lateral intercondylar ridge, deeply positioned with longitudinal axis close to the extension line of posterior cortical part of femur, coinciding with the distribution of direct fibers. There was contradiction on whether anterior cruciate ligament near-isometric reconstruction areas and anterior cruciate ligament anatomic insertion sites overlapped with each other. The most isometric area within the anatomic insertion site was the area of anterior fibers near lateral intercondylar ridge, which carried a large portion of the total anterior cruciate ligament load. Generally, there was a scarce of clinical researches in the field of isometry of ACLR. For the purpose of attesting the accuracy of the results we found, a combination of intra-operative observation on the displacement of graft relative to bone-tunnel and post-operative imaging such as MRI and three dimensional CT should be considered.

Tibial insertion of the anterior cruciate ligament and anterior horn of the lateral meniscus share the lateral slope of the medial intercondylar ridge: A computed tomography study in a young, healthy population

BackgroundThe central intercondylar ridge (CIR) is an anatomical bony landmark that bisects the slope of the medial intercondylar ridge (MIR) between the tibial insertion of the anterior cruciate ligament (ACL) and anterior horn of lateral meniscus (AHLM) and was recently revealed by computed tomography (CT) evaluation corresponding to histologic slices of cadaveric knees. The purpose of this study was to clarify the shape and size of ACL and AHLM tibial insertion in young, healthy knees using the new bony landmark (CIR) and previously reported landmarks. MethodsThe contralateral healthy knees in 34 ACL-reconstructed patients (18 male patients, 16 female patients, mean age: 24.0 years) were scanned by CT. In the reconstructed coronal/sagittal images, bony landmarks of ACL (anterior: anterior ridge, posterior: blood vessel in tubercle fossa, medial: MIR, lateral: CIR) and AHLM (medial: CIR, lateral: bottom of the slope) were plotted for evaluation. The length of sagittal slices and the width in five coronal slices of the insertion were measured. ResultsThe ACL insertion consistently showed a boot-like-shape adjacent to the square shape of AHLM on three-dimensional imaging. The mean ACL sagittal length was 14.5 ± 1.9 mm, while the mean ACL widths (in mm) from anterior to posterior were 12.7 ± 2.7, 8.1 ± 1.9, 7.9 ± 2.0, 7.5 ± 1.5, and 7.2 ± 1.6, which was highly correlated with the tibial plateau size. ConclusionsThe boot-like-shape of the ACL tibial footprint insertion shared the slope of MIR with the rectangular shape of AHLM in young, healthy knees. This study may provide useful information for safe tibial tunnel creation at the time of ACL reconstruction.

Is There A Relationship Between Three-Dimensionally Measured Baker's Cyst Volume and Knee Pathologies?

Baker's cyst (BC) is also known as popliteal cyst. To evaluate its effect on intra-articular pathology, it is important to have the exact volume of the cyst. As BC may change its shape due to mass effect of the surrounding anatomic structures, it is difficult to measure the exact volume of BC. This study examined the relationship between three-dimensionally measured BC volume and symptomatic intra-articular knee pathologies. The magnetic resonance (MR) images of 45 patients with symptomatic knees were retrospectively examined.The BC volumes were measured via volumetric analysis. The joint effusion was examined in the sagittal plane in T2-proton density-weighted images. The medial plicae were assessed in accordance with the modified Sakakibara classification. Using the MR images, the meniscuses were classified in accordance with the meniscus rupture classification of Stoller et al. The cartilaginous lesions were analyzed using an MR grading system.In this study, correlations between the following measures were analyzed: BC volume and effusion level, medial plica presence, medial femoral condyle, medial tibial condyle, lateral femoral condyle and lateral tibial condyle cartilage degeneration, and medial meniscus anterior horn, medial meniscus posterior horn, lateral meniscus anterior and posterior horn ruptures. Cartilage degeneration, medial plicae, increase in intra-articular effusion, and increase in the BC volume were found to be statistically significant (p<0.01). Cartilage degeneration, medial plicae, and increase in intra-articular effusion may increase the BC volume. We believe that this study may contribute to clinicians in understanding the relationship between BC volume changes and pathologies causing intra-articular knee symptoms.

Anatomical relationship between insertion sites, tunnel placement, and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PurposeThe influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury. MethodsForty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically. ResultsTibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia. ConclusionsThe incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.

Anterior cruciate ligament tibial insertion site is elliptical or triangular shaped in healthy young adults: high-resolution 3-T MRI analysis.

To clarify the morphology of anterior cruciate ligament (ACL) tibial insertion site in healthy young knees using high-resolution 3-T MRI. Subjects were 50 ACL-reconstructed patients with a mean age of 21.4±6.8years. The contralateral healthy knees were scanned using high-resolution 3-T MRI. The tibial insertion sites of the anteromedial (AM) and posterolateral (PL) bundle fibres, and the ACL attachment on the anterior horn of lateral meniscus (AHLM) were segmented from the MR images, and 3D models were reconstructed to evaluate the morphology. The shape of ACL footprint was qualitatively analysed, and the size of AM and PL attachments and AHLM overlapped area was measured digitally. Tibial AM and PL bundles were clearly identified in 42 of 50 knees (84.0%). Morphology of the whole ACL tibial insertion site was elliptical in 23 knees (54.8%) and triangular in 19 knees (45.2%), but not classified as C-shape in any knees. However, the AM bundle attachment was of C-shape in 29 knees (69.0%) and band-like in 13 knees (31.0%). Overlap of ACL on AHLM was found in 26 knees (61.9%), and the size of the overlapped area was 4.8±4.7% of the whole ACL insertion site. 3D morphology of the intact ACL tibial insertion site analysed by high-resolution 3-T MRI was elliptical or triangular in healthy young knees. However, the AM bundle insertion site was of C-shape or band-like. A small lateral portion of the ACL was overlapped with the AHLM. As for clinical relevance, these findings should be considered in order to reproduce the native ACL insertion site sufficiently. III.

T1rho and T2 relaxation times of the normal adult knee meniscus at 3T: analysis of zonal differences

BackgroundPrior studies describe histological and immunohistochemical differences in collagen and proteoglycan content in different meniscal zones. The aim of this study is to evaluate horizontal and vertical zonal differentiation of T1rho and T2 relaxation times of the entire meniscus from volunteers without symptom and imaging abnormality.MethodsTwenty volunteers age between 19 and 38 who have no knee-related clinical symptoms, and no history of prior knee surgeries were enrolled in this study. Two T1rho mapping (b-FFE T1rho and SPGR T1rho) and T2 mapping images were acquired with a 3.0-T MR scanner. Each meniscus was divided manually into superficial and deep zones for horizontal zonal analysis. The anterior and posterior horns of each meniscus were divided manually into white, red-white and red zones for vertical zonal analysis. Zonal differences of average relaxation times among each zone, and both inter- and intra-observer reproducibility were statistically analyzed.ResultsIn horizontal zonal analysis, T1rho relaxation times of the superficial zone tended to be higher than those of the deep zone, and this difference was statistically significant in the medial meniscal segments (84.3 ms vs 76.0 ms on b-FFE, p < 0.0001 and 96.5 ms vs 91.7 ms on SPGR, p = 0.004). In vertical zonal analysis, T1rho relaxation times of the white zone tended to be higher than those of the red zone, and this difference was statistically significant in the posterior horn of the medical meniscus (88.4 ms vs 77.1 ms on b-FFE, p < 0.001 and 104.9 ms vs 96.8 ms on SPGR, p =0.001). Likewise, T2 relaxation times of the superficial zone were significantly higher than those of the deep zone (80.4 ms vs 74.4 ms in the medial meniscus, p = 0.011). T2 relaxation times of the white zone were significantly higher than those of the red zone in the medial meniscus posterior horn (96.8 ms vs 84.3 ms, p < 0.001) and lateral meniscus anterior horn (104.6 ms vs 84.2 ms, p < 0.0001). Inter-class and intra-class correlation coefficients were excellent (>0.74) or good (0.60–0.74) in all meniscal segments on both horizontal and vertical zonal analysis, except for inter-class correlation coefficients of the lateral meniscus on SPGR. Compared with SPGR T1rho images, b-FFE T1rho images demonstrated more significant zonal differentiation with higher inter- and intra-observer reproducibility.ConclusionsThere are zonal differences in T1rho and T2 relaxation times of the normal meniscus.

The prevalence and characteristics of a subcortical cystic lesion at the subspinous region of the knee.

Background Although we observed that subcortical cysts near the attachment of the meniscus or cruciate ligaments are frequently seen with a tear or degeneration of the adjacent meniscus and/or cruciate ligament, there is no large study describing the prevalence, distribution, and associated findings of these cysts. Purpose To evaluate the prevalence and distribution of subcortical cysts near the attachments of the meniscus or cruciate ligaments and evaluate pathologies of the meniscus or cruciate ligaments using magnetic resonance imaging (MRI). Material and Methods We reviewed 1009 knee MRIs for the presence of subcortical cysts near the meniscus or cruciate ligament attachments and evaluated their size, location, edema of the adjacent bone marrow, and integrities of the medial and lateral meniscus and anterior and posterior cruciate ligaments. Results The 110 cysts were found in either the middle (n = 56), posterior (n = 52), or anterior (n = 2) subspinous regions. Sixty-two were at meniscal root insertion, including seven at the lateral meniscus anterior horn, five at the lateral meniscus posterior horn, 48 at the medial meniscus posterior horn, and two at the medial meniscus anterior horn. All were associated with an adjacent meniscal pathology. Of the 34 cysts at the anterior cruciate ligament (ACL) insertion, 28 had ACL pathology. Nine cysts had surrounding edema in the adjacent bone marrow. Conclusion Subcortical cysts at the subspinous region of the knee were seen in 9.6% of knee MRI examinations. Most were in close proximity to the meniscal or cruciate ligaments with associated pathologies, suggesting that abnormal stress on the bone induces cyst formation.

Arthroscopic Management for the Unstable Inferior Leaf of the Lateral Meniscus Anterior Horn and Associated Cysts through a Direct Inframeniscal Portal: A Retrospective Study.

Introduction To investigate the clinical results of arthroscopic management for the unstable inferior leaf of the lateral meniscus anterior horn and associated cysts through an inframeniscal portal. Methods From March 2005 to October 2014, 64 patients with an unstable inferior leaf of the lateral meniscus anterior horn and associated cysts underwent arthroscopic management with an inframeniscal portal. The mean age of the patients was 36.9 years (range, 18 to 49 years). The mean follow-up period was 28 months (range, 24 to 44 months). Clinical results were assessed using physical examination, the Lysholm knee score, and postoperative magnetic resonance scanning. Results The median Lysholm score improved significantly at 1 year after surgery and at final follow-up. Magnetic resonance scanning at least one year after the operation revealed no recurrent meniscal tears or cysts. No reoperations were required after an average follow-up of 28 months. All patients reported significant symptomatic relief after the operation. They had full range of motion at three months and returned to normal activities and sports one year after surgery. ConclusionThe direct inframeniscal portal can provide an effective approach to manage lesions in the anterior horn of the lateral meniscus with predictable clinical outcomes.

Remnant-Preserving Tibial Tunnel Positioning Using Anatomic Landmarks in Double-Bundle Anterior Cruciate Ligament Reconstruction

To assess (1) if 6 anatomic landmarks (ALs) could be arthroscopically confirmed with remnant preservation and (2) if creating tibial tunnels using these landmarks reduces individual variation and improves reproducibility in double-bundle anterior cruciate ligament (ACL) reconstruction. We retrospectively reviewed data of patients who chronologically underwent double-bundle ACL reconstruction by either referencing the footprint after remnant dissection (non-AL group) or subsequently with the ALs (AL group). Using operative videos, 3 independent observers judged whether they could confirm 6 ALs (medial intercondylar ridge, medial and lateral intercondylar tubercles, anterior horn of lateral meniscus, Parsons' knob, and L-shaped ridge) in 20 patients randomly selected from the AL group. We then compared tunnel positions between the 2 groups, measured from the anterior and medial borders of the proximal tibia and expressed as percentage of the total depth and width of the proximal tibia using 3-dimensional computed tomography. One hundred four patients (non-AL group, n= 54; AL group, n= 50) were included. All 6 ALs were arthroscopically confirmed in most cases (89.7% to 100%). The mean percentages of the anteroposterior (AP) depth for anteromedial (AM) tunnel, mediolateral (ML) width for AM tunnel, AP depth for posterolateral (PL) tunnel, and ML width for PL tunnel, respectively, were 27.8% ± 6.6%, 46.7% ± 2.8%, 41.4% ± 7.3%, and 46.1% ± 2.6% for the non-AL group and 30.7% ± 4.5%, 45.7% ± 2.2%, 45.2% ± 4.5%, and 46.9% ± 2.1% for the AL group, revealing significantly less variation in the AL group compared with the non-AL group, excluding the ML width of the PL tunnel (P= .007, .046, .002, .209, respectively). Six landmarks could be reliably confirmed in cases with remnant preservation, and creating tibial tunnels using these landmarks were reproducible and resulted in less individual variation. Level III, retrospective comparative study.

Bony morphology of the knee and non-traumatic meniscal tears: is there a role for meniscal impingement?

Meniscal tears are an important cause of morbidity. The aim of this study was to examine the relationship between non-traumatic meniscal tears and the intrinsic bony morphology of the knee. A retrospective analysis of 160 knee MRI scans in 150 patients was carried out who met the following criteria: (a) age between 20 and 45 years, (b) no history of knee trauma, surgery, infection, metabolic bone disease, and (c) no collateral or cruciate ligamentous injury. The medial tibial slope (MTS), lateral tibial slope (LTS), medial tibial plateau depth (MTPD), and medial and lateral femoral condylar offset ratios were calculated. The anterior horn, body, and posterior horn of the menisci were graded as 0 (no tear), 1 and 2 (degenerative changes), or 3 (definitive tear). One-way ANOVA and linear regression was used for statistical analysis. In patients with grade 3 tears of the posterior horn of the medial meniscus, there was a significant association with shallower MTS (p < 0.05), smaller medial femoral offset ratio (p < 0.05) and smaller lateral femoral offset ratio (p < 0.05). Patients with grade 3 tears of anterior horn of the lateral meniscus had a significant association with shallower LTS (p < 0.05). No significant association was seen between MTPD and meniscal tears. Our results suggest an association between bony morphology of the knee and non-traumatic meniscal tears. Shallower MTS and LTS may result in impingement of posterior horn of medial meniscus and anterior horn of lateral meniscus, respectively. Future kinematic studies will be needed to help confirm our findings.

A Standardized Technique in Performing Pivot-Shift Test on the Knee Joint Provided More Consistent Acceleration Curve Shape, Allowing to Highlight Side-to-Side Differences

A standardized technique in performing pivot-shift test on the knee joint provided more consistent acceleration curve shape, allowing to highlight side-to-side differences. The pivot-shift (PS) test is commonly used to evaluate knee joint dynamic laxity; the PS maneuver is yet highly surgeon-specific and difficult to quantify, thus creating high variability in objective grading. Several non-invasive devices and methods have been proposed to quantify the PS phenomenon, above all, using acceleration [1] and inertial sensors [2,3] The aim of this study was to analyze acceleration signal, evaluating the variability in performing both the surgeon-specific technique and a standardized technique, quantified by means of a triaxial acceleration sensor. We hypothesized that the standardized maneuver would be able to better discriminate PS grade compared to the surgeon-specific one. A complete lower body specimen was used for the study. Two different instability grades were created on right and left knee, cutting the ACL and the ACL plus the anterior horn of lateral meniscus, respectively. Twelve expert surgeons performed 3 repetitions of PS test based on their preferred technique followed by a standardized one. A triaxial acceleration sensor skin-fixed to the proximal tibia [3] was used. Comparisons on normalized acceleration curves were performed analyzing side-to-side differences between the surgeon-specific technique and the standardized technique (Independent Student's t-test). Signals with evidence of major inconsistencies were excluded. Statistical significance was set at the 95% level (p < 0.05). Mean acceleration curves for the personal technique presented low differences - both in shape and in values - between right and left limb; generally the right limb presented lower values of acceleration on the whole curve, but they - and above all the value about the maximum and minimum peak - were not statistically different. Standardized technique highlighted bigger side-to-side differences on the whole curves, above all for what concerned the values between the maximum and minimum peak, that were statistically different. The shapes were also different, highlighting an inflexion between the maximum and minimum value for the right limb. Moreover the variability between the tests performed with standardized technique was reduced, compared to the personal one. We found a reduction of the variability of the curve between tester when using the standardized maneuver. Moreover the trend of the acceleration curves more coherent in standardized PS. Although further studies are required, the acceleration parameter - when standardized technique is performed - seems sensitive enough to allow discrimination of instability grades during PS test.

A New Surgical Technique of Arthroscopic Partial Meniscectomy for Unstable Inferior Leaf of the Anterior Horn in a Horizontal Tear of Lateral Meniscus

We introduce a new arthroscopic partial meniscectomy technique using a three portals and a small skin hook retractor to remove unstable inferior leaf in horizontal meniscal tear that involved the anterior portion of the lateral meniscus. The patient is positioned for a standard knee arthroscopy. After careful estimation of the depth and extent of the cleft and stability of the superior and inferior leaves is done through the standard anteromedial portal, a small skin hook retractor is inserted through the standard anterolateral portal to raise the dominant superior leaf of anterior horn, then the unstable inferior leaf is excised with a 90° rotary punch and a motorized shaver through the extreme far anteromedial portal. This technique is useful method to remove unstable inferior leaf of anterior horn of lateral meniscus which is difficult to remove with a standard technique.