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Background: Quantitative magnetic resonance (MR) imaging techniques are established for evaluation of cartilage composition and trabecular bone microstructure at the knee. It remains unclear whether quantitative MR parameters predict the midterm morphological outcome after matrix-associated chondrocyte implantation (MACI) with autologous bone grafting (ABG)., Purpose: To assess longitudinal changes and associations of the biochemical composition of cartilage repair tissue, the subchondral bone architecture, and morphological knee joint abnormalities on 3-T MR imaging after MACI with ABG at the knee., Study Design: Case series; Level of evidence, 4., Methods: Knees of 18 patients (28.7 ± 8.4 years [mean ± SD]; 5 women) were examined preoperatively and 3, 6, 12, and 24 months after MACI and ABG using 3-T MR imaging. Cartilage composition was assessed using T 2 relaxation time measurements. Subchondral bone microstructure was quantified using a 3-dimensional phase-cycled balanced steady-state free precision sequence. Trabecular bone parameters were calculated using a dual threshold algorithm (apparent bone fraction, apparent trabecular number, and apparent trabecular separation). Morphological abnormalities were assessed using the MOCART (magnetic resonace observation of cartilage repair tissue) score, the WORMS (Whole-Organ Magnetic Resonance Imaging Score), and the CROAKS (Cartilage Repair Osteoarthritis Knee Score). Clinical symptoms were assessed using the Tegner activity and Lysholm knee scores. Statistical analyses were performed by using multiple linear regression analysis., Results: Total WORMS ( P = .02) and MOCART ( P = .001) scores significantly improved over 24 months after MACI. Clinical symptoms were significantly associated with the presence of bone marrow edema pattern abnormalities 24 months after surgery ( P = .035). Overall there was a good to excellent radiological outcome found after 24 months (MOCART score, 88.8 ± 10.1). Cartilage repair T 2 values significantly decreased between 12 and 24 months after MACI ( P = .009). Lower global T 2 values after 3 months were significantly associated with better MOCART scores after 24 months ( P = .04). Moreover, trabecular bone parameters after 3 months were significantly associated with the total WORMS after 24 months (apparent bone fraction, P = .048; apparent trabecular number, P = .013; apparent trabecular separation, P = .013)., Conclusion: After MACI with ABG, early postoperative quantitative assessment of biochemical composition of cartilage and microstructure of subchondral bone may predict the outcome after 24 months. The perioperative global joint cartilage matrix quality is essential for proper proliferation of the repair tissue, reflected by MOCART scores. The subchondral bone quality of the ABG site is essential for proper maturation of the cartilage repair tissue, reflected by cartilage T 2 values.

Background: For focal cartilage defects, biological repair might be ineffective in patients over 45 years. A focal metallic implant (FMI) (Hemi-CAP Arthrosurface Inc., Franklin, MA, USA) was designed to reduce symptoms. The aim of this study was to evaluate the effects of a FMI on the opposing tibial cartilage in a biomechanical set-up. It is hypothesized that a FMI would not damage the opposing cartilage under physiological loading conditions., Methods: An abrasion machine was used to test the effects of cyclic loading on osteochondral plugs. The machine applied a compressive load of 33 N and sheared the samples 10 mm in the anteroposterior direction by 1 Hz. Tibial osteochondral plugs from porcine knees were placed in opposition to a FMI and cycled for 1 or 6 h. After testing each plug was fixed, stained and evaluated for cartilage damage., Results: After 1 h of loading (n = 6), none of the osteochondral plugs showed histologic signs of degradation. After 6 h of loading (n = 6) three samples had histologic signs of injury in the tangential zone (grade 1) and one had signs of injury in the transitional and deep zones (grade 2). Exploration for 6 h resulted in significant more cartilage damage compared to the shorter exploration time (p = 0.06). However, no significant difference between saline and hyaluronic acid was evident (p = 0.55)., Conclusion: Under physiologic loading conditions, contact with a FMI leads to cartilage damage in the opposing articular cartilage in six hours. In clinical practice, a thorough analysis of pre-existing defects on the opposing cartilage is recommended when FMI is considered.

Purpose: Arthroscopic partial meniscectomy of medial meniscus tears and varus alignment are considered independent risk factors for increased medial compartment load, thus contributing to the development of medial osteoarthritis. The purpose of this biomechanical study was to investigate the effect of lower limb alignment on contact pressure and contact area in the knee joint following sequential medial meniscus resection. It was hypothesized that a meniscal resection of 50% would lead to a significant overload of the medial compartment in varus alignment., Methods: Eight fresh-frozen human cadaveric knees were axially loaded with a 750 N compressive force in full extension with the mechanical axis rotated to intersect the tibia plateau at 30%, 40%, 50%, 60% and 70% of its width. Tibiofemoral mean contact pressure (MCP), peak contact pressure (PCP), and contact area (CA) of the medial and lateral compartment were measured separately using pressure-sensitive films (K-Scan 4000, Tekscan) in four different meniscal conditions, respectively, intact, 50% resection, 75% resection, and total meniscectomy., Results: Medial MCP was significantly increased when comparing the intact meniscus to each meniscal resection in all tested alignments (p < 0.05). Following meniscal resection of 50%, MCP was significantly higher with greater varus alignment compared to valgus alignment (p < 0.05). Similarly, medial PCP was higher at varus alignment compared to valgus alignment (p < 0.05). Further resection to 75% and 100% of the meniscus resulted in a significantly higher medial PCP at 30% of tibia plateau width compared to all other alignments (p < 0.05). Medial CA of the intact meniscus decreased significantly after 50%, 75% and 100% meniscal resection in all alignments (p < 0.05). Lateral joint pressure was not significantly increased by greater valgus alignment., Conclusion: Lower limb alignment and the extent of medial meniscal resection significantly affect tibiofemoral contact pressure. Combined varus alignment and medial meniscal resection increased MCP and PCP within the medial compartment, whereas valgus alignment prevented medial overload. As a clinical consequence, lower limb alignment should be considered in the treatment of patients undergoing arthroscopic partial meniscectomy with concomitant varus alignment. In patients presenting with ongoing medial joint tenderness and effusion, realignment osteotomy can be a surgical technique to unload the medial compartment.

Purpose: Assessment of medial meniscus extrusion (MME) has become increasingly popular in clinical practice to evaluate the dynamic meniscus function and diagnose meniscus pathologies. The purpose of this biomechanical study was to investigate the correlation between MME and the changes in joint contact pressure in varus and valgus alignment. It was hypothesized that varus alignment would result in significantly higher MME along with a higher joint contact pressure in the medial compartment., Methods: Eight fresh-frozen human cadaveric knees were axially loaded, with a 750 N compressive load, in full extension with the mechanical axis shifted to intersect the tibial plateau at 30% and 40% (varus), 50% (neutral), 60% and 70% (valgus) of its width (TPW). Tibiofemoral peak contact pressure (PCP), mean contact pressure (MCP) and contact area (CA) were determined using pressure-sensitive films. MME was obtained via ultrasound at maximum load., Results: MME was significantly increased from valgus (1.32 ± 0.22 mm) to varus alignment (3.16 ± 0.24 mm; p < 0.001). Peak contact pressure at 30% TPW varus alignment was significantly higher compared to 60% TPW valgus (p = 0.018) and 70% TPW valgus (p < 0.01). MME significantly correlated with PCP (r = 0.56; p < 0.001) and MCP (r = 0.47, p < 0.01) but not with CA (r = 0.23; n.s.)., Conclusion: MME was significantly increased in varus alignment, compared to neutral or valgus alignment, with an intact medial meniscus. It was also significantly correlated with PCP and MCP within the medial compartment. However, valgus malalignment and neutral axis resulted in reduced MME and contact pressure. Lower limb alignment must be taken into account while assessing MME in clinical practice., Level of Evidence: Controlled laboratory study.

Background: Clinical cartilage repair strategies can be tested using the sheep model as suggest by the European Medicines Agency. To characterize variation within the joint a full biomechanical mapping is necessary. The aim of this study is to establish a loading model, to map regional differences within the knee and determine reference areas for area specific replacement techniques., Methods: A porous indenter was selected to evaluate 22 defined test locations (femoral condyles, tibia plateau, patella, femoral groove) on ovine knees (n = 7). A high-dynamic force-controlled micro creep and creep-recovery indentation test system applied five loading (0.11 MPa) and unloading (5.6 kPa) cycles for 60 s each and recorded creep-recovery. Needle indentation was used to measure cartilage thickness and calculate total strain., Findings: Steady state behaviour was observed from the third cycle and further evaluated. Little variation of stiffness in N/mm was found within the patella (4.3SD0.5) and femoral groove (8.1SD0.7) compared to larger variations in the femur (7.9SD2.0) and tibia (7.5SD3.2). Creep indentation showed values of 14.5%(SD2.7%) for the patella and 17.4%(SD3%) for the femoral grove opposed to 13.4%(SD4.3%) for the femoral condyles and 21.8%(SD6.6%) for the tibia plateau. Similar trends were observed analysing creep-recovery. Values were normalized to cartilage thickness which ranged between 0.36 mm and 1.14 mm., Interpretation: Our setup allows a reliable evaluation of zonal differences. Homogenous biomechanical behaviour is found within the patella and femoral groove whereas significant biomechanical variation within the femoral condyles and tibia plateau indicates the need for site-specific cartilage repair products., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the stabilizing effect of a lateral meniscus posterior root repair in an ACL and root deficient knee., Methods: The hypothesis of the current study was that a sequential transection of the posterior root and the meniscofemoral ligaments in an ACL-deficient knee increases rotational instability, and conversely, a repair of the meniscus root reduces the internal tibial rotation. Therefore, eight human knee joints were tested in a robotic setup (5 N m internal torque, 50 N m anterior translation load). Five conditions were tested: intact, ACL cut, ACL cut + lateral meniscus posterior root tear (LMRT), ACL cut + LMRT + transection of the MFL and ACL cut + lateral meniscus root repair. The angles of internal tibial rotation as well as anterior tibial translation were recorded., Results: Transection of the lateral meniscus posterior root increased the internal tibial instability as compared to the ACL-insufficient state. A significant increase was detected in 60° and 90° of flextion. Sectioning of the meniscofemoral ligament further destabilized the knees significantly at all flexion angles as compared to the ACL-deficient state. Even in 30°, 60° and 90° a significant difference was detected as compared to the isolated root tear. A tibial fixation of the lateral meniscus root reduced the internal tibial rotation in all flexion angles and led to a significant decrease of internal tibial rotation in 30° and 90° as compared to the transection of the root and the MFL. The anterior tibial translation was increased in all conditions as compared to the native state., Conclusion: A lateral meniscus root repair can reduce internal tibial rotation in the ACL-deficient knee. To check the condition of the lateral posterior meniscus root attachment is clinical relevant as a lateral meniscus root repair might improve rotational stability.

Background: Previously published data indicate that BMP-2 gene activated muscle tissue grafts can repair large bone defects in rats. This innovative abbreviated ex vivo gene therapy is appealing because it does not require elaborative and time-consuming extraction and expansion of cells. Hence, in the present study, we evaluated the potential of this expedited tissue engineering approach for regenerating osteochondral defects in rabbits., Methods: Autologous muscle tissue grafts from female White New Zealand rabbits were directly transduced with an adenoviral BMP-2 vector or remained unmodified. Osteochondral defects in the medial condyle of rabbit knees were treated with either BMP-2 activated muscle tissue implants or unmodified muscle tissue or remained empty. After 13 weeks, repair of osteochondral defects was examined by biomechanical indentation testing and by histology/imunohistochemistry applying an extended O'Driscoll scoring system and histomorphometry., Results: Biomechanical investigations revealed a trend towards slightly improved mechanical properties of the group receiving BMP-2 activated muscle tissue compared to unmodified muscle treatment and empty defect controls. However, a statistically significant difference was noted only between BMP-2 muscle and unmodified muscle treatment. Also, histological evaluation resulted in slightly higher histological scores and improved collagen I/II ratio without statistical significance in the BMP-2 treatment group. Histomorphometry indicated enhanced repair of subchondral bone after treatment with BMP-2 muscle, with a significantly larger bone area compared to untreated defects., Conclusions: Gene activated muscle tissue grafts showed potential for osteochondral defect repair. There is room for improvement via the use of appropriate growth factor combinations., (Copyright © 2017 John Wiley & Sons, Ltd.)

Background: Meniscus extrusion or hypertrophy may occur in knee osteoarthritis (OA). However, currently no data are available on the position and size of the meniscus in asymptomatic men and women with normal meniscus integrity., Methods: Three-dimensional coronal DESSwe MRIs were used to segment and quantitatively measure the size and position of the medial and lateral menisci, and their correlation with sex, height, weight, and tibial plateau area. 102 knees (40 male and 62 female) were drawn from the Osteoarthritis Initiative "non-exposed" reference cohort, including subjects without symptoms, radiographic signs, or risk factors for knee OA. Knees with MRI signs of meniscus lesions were excluded., Results: The tibial plateau area was significantly larger (p < 0.001) in male knees than in female ones (+23% medially; +28% laterally), as was total meniscus surface area (p < 0.001, +20% medially; +26% laterally). Ipsi-compartimental tibial plateau area was more strongly correlated with total meniscus surface area in men (r = .72 medially; r = .62 laterally) and women (r = .67; r = .75) than contra-compartimental or total tibial plateau area, body height or weight. The ratio of meniscus versus tibial plateau area was similar between men and women (p = 0.22 medially; p = 0.72 laterally). Tibial coverage by the meniscus was similar between men and women (50% medially; 58% laterally), but "physiological" medial meniscal extrusion was greater in women (1.83 ± 1.06mm) than in men (1.24mm ± 1.18mm; p = 0.011)., Conclusions: These data suggest that meniscus surface area strongly scales with (ipsilateral) tibial plateau area across both sexes, and that tibial coverage by the meniscus is similar between men and women.

To restore walking after transfemoral amputation, various actuated exoprostheses have been developed, which control the knee torque actively or via variable damping. In both cases, an important issue is to find the appropriate control that enables user-dominated gait. Recently, we suggested a generic method to deduce intended motion of impaired or amputated limbs from residual human body motion. Based on interjoint coordination in physiological gait, statistical regression is used to estimate missing motion. In a pilot study, this complementary limb motion estimation (CLME) strategy is applied to control an active knee exoprosthesis. A motor-driven prosthetic knee with one degree of freedom has been realized, and one above-knee amputee has used it with CLME. Performed tasks are walking on a treadmill and alternating stair ascent and descent. The subject was able to walk on the treadmill at varying speeds, but needed assistance with the stairs, especially to descend. The promising results with CLME are compared with the subject's performance with her own prosthesis, the C-Leg from Otto Bock.

Objective: Magnetic resonance imaging (MRI) of articular cartilage has evolved to be an important tool in research on cartilage (patho)physiology and osteoarthritis (OA). MRI provides a wealth of novel and quantitative information, but there exists no commonly accepted terminology for reporting these metrics. The objective of this initiative was to propose a nomenclature for definitions and names to be used in scientific communications and to give recommendations as to which minimal methodological information should be provided when reporting MRI-based measures of articular cartilage in OA., Methods: An international group of experts with direct experience in MRI measurement of cartilage morphology or composition reviewed the existing literature. Through an iterative process that included a meeting with a larger group of scientists and clinicians (December 2nd, 2004, Chicago, IL, USA), they discussed, refined, and proposed a nomenclature for MRI-based measures of articular cartilage in OA., Results: The group proposes a nomenclature that describes: (1) the anatomical location and (2) the structural feature being measured, each name consisting of a metric variable combined with a tissue label. In addition, the group recommends minimal methodological information that should be described., Conclusions: Utilization of this nomenclature should facilitate communication within the scientific community. Further, the uniform adoption of comprehensive nomenclature to describe quantitative MRI- features of articular cartilage should strengthen epidemiological, clinical, and pharmacological studies in OA.

Recent studies have shown that thinning of human cartilage occurs with unloading, but no data are available on the effect of remobilization (after immobilization) on knee joint cartilage status in humans. We examined a 36-year-old patient after 6 weeks of unilateral immobilization. Knee joint cartilage morphology (patella and tibia), patellar cartilage deformation, and thigh muscle cross-sectional areas were assessed with quantitative MR imaging and bone density with peripheral quantitative computed tomography (pQCT) during 24 months of remobilization. The immobilized limb displayed lower muscle cross-sectional areas (MCSA) of the knee extensors (-36%), lower bone density of the femur and tibia (-12/-6%), lower patellar cartilage thickness (-14%), but no side differences of tibial cartilage thickness. During remobilization, side differences decreased to -4% for knee extensor MCSAs, to -6%/-3% for femoral and tibial BMD, and to -8% for patellar cartilage thickness. No change was observed in tibial cartilage. Patellar deformation decreased from 9% to 4% after 15 months. In conclusion, we observed substantial changes of thigh MCSAs, but little (patella) to no (tibia) change in cartilage thickness during remobilization. These preliminary results indicate that human cartilage macro-morphology may be less adaptive to variations of the mechanical loading than muscle and bone.

An analytical, dynamic model of the human knee joint has been developed to simulate the unloaded knee joint behaviour in 6 degrees of freedom. It is based on extensive robot-based measurements of the elastic properties of a human cadaver knee joint. The measured data are compared with data from the literature to ensure that a proper database for modelling is used. The analytical modelling of the passive elastic joint properties is done with Local Linear Model Trees. The deduced knee joint model incorporates passive elastic properties of the internal knee joint structures, passive elastic muscle forces, damping forces, gravitational forces, and external forces. There are two sets of parameters, one simulating the movement of the intact knee joint, and a second simulating the knee joint with ruptured anterior cruciate ligament. The dynamic model can be easily processed in real-time. It is implemented in the haptic display of the Munich Knee Joint Simulator (MKS), which enables a person to move a plastic leg driven by a robot manipulator and feel the simulated knee joint force. Orthopaedic physicians judged the performance of the dynamic knee joint model by executing physical knee joint tests at the MKS.

Background: Arthrotic deformities with changes in knee geometry can produce difficulties in implanting long stem knee prosthesis systems using intramedullary alignment. They can result in incorrect lower limb axis and prosthesis positioning. The aim of the presented study was to measure knee geometry in patients with varus and valgus gonarthrosis in order to define diagnosis related differences., Methods: A total of 75 patients with indication for total knee arthroplasty were divided in two groups using the weight bearing lower limb axis: patients with varus gonarthrosis (n=43) and with valgus gonarthrosis (n=32). Angles and extensions, important for knee prosthesis implantation, were measured, digitalized and analyzed. The results were investigated for diagnosis specific differences., Results: After regulation of the measured extension in mean femur/tibia lengths, significant diagnosis specific differences were found: femur condyles were widened towards pathologic weight bearing (P<0.044), and the mechanical tibia axis of the varus gonarthrosis group is transferred to the lateral side (P<0.046) and in projection over the lateral internal cortical substance., Conclusion: The significant differences in deformed arthrotic knees indicate that for an optimal postoperative result the use of standard implants is not always sufficient. Modular knee prosthesis systems can provide adequately for individual demands.

Simulation environments based on virtual reality technologies can support medical education and training. In this paper, the novel approach of an "interactive phantom" is presented that allows a realistic display of haptic contact information typically generated when touching and moving human organs or segments. The key idea of the haptic interface is to attach passive phantom objects to a mechanical actuator. The phantoms look and feel as real anatomical objects. Additional visualization of internal anatomical and physiological information and sound generated during the interaction with the phantom yield a multimodal approach that can increase performance, didactic value, and immersion into the virtual environment. Compared to classical approaches, this multimodal display is convenient to use, provides realistic tactile properties, and can be partly adjusted to different, e.g., pathological properties. The interactive phantom is exemplified by a virtual human knee joint that can support orthopedic education, especially for the training of clinical knee joint evaluation. It is suggested that the technical principle can be transferred to many other fields of medical education and training such as obstetrics and dentistry.

Objective: Follow up of osteoarthritis (OA) and evaluation of structure modifying OA drugs require longitudinal data on cartilage structure. The aim of this study was to analyse the long term and resegmentation precision of quantitative cartilage analysis with magnetic resonance imaging (qMRI) in vivo, and to relate precision errors to the estimated cartilage loss in OA., Method: Sagittal MR images of the knee were obtained in 14 individuals, four datasets being acquired in a first imaging session. In 12 subjects, two further datasets were acquired over the next months. Image analysis was performed in the same session for image data obtained under short-term and long-term imaging conditions, and in three different sessions (months apart) for the first data set (resegmentation precision)., Results: Long-term precision errors ranged from 1.4% (total knee) to 3.9% (total femur) for cartilage volume and thickness and were only marginally higher than those under short term conditions. In the medial tibia, the error was 84 mm(3) compared with an estimated loss of >1,200 mm(3) in varus OA. Precision errors for resegmentation were somewhat higher, but considerably smaller than the intersubject variability., Conclusions: Scanner drift and changes in imaging or patient conditions appear not to represent a critical problem in quantitative cartilage analysis with magnetic resonance imaging (qMRI). In longitudinal studies, image analysis of sequential data should be performed within the same post-processing session. Under these conditions, qMRI promises to be a very powerful method to assess structural change of cartilage in OA., (Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd.)

In orthopaedics more than 50 different clinical knee joint evaluation tests exist that have to be trained in orthopaedic education. Often it is not possible to obtain sufficient practical training in a clinical environment. The training can be improved by Virtual Reality technology. In the frame of the Munich Knee Joint Simulation project an artificial leg with anatomical properties is attached by a force-torque sensor to an industrial robot. The recorded forces and torques are the input for a simple biomechanical model of the human knee joint. The robot is controlled in such way that the user gets the feeling he moves a real leg. The leg is embedded in a realistic environment with a couch and a patient on it.

Due to limited simultaneous access to a greater pool of patients an effective training of medical students or young orthopedic physicians is difficult. A knee joint simulator that comprises the properties of a healthy or pathological knee can support medical education and training. In this paper a mechatronic system is presented that provides visual, acoustic, and haptic (force) feedback so that it allows a user to touch and move a virtual shank, bones or muscles within the leg, and simultaneously observe the generated movement, feel the contact force, and hear sounds. These and further features enable the user to study and assess the properties of the knee, e.g. by testing the joint laxity and end-point stiffness in six degrees-of-motion (DOF) and by grasping and pulling at muscles, rupturing ligaments or changing muscle/ligament paths. Such a tool can support training of physical knee evaluation required for diagnosis and therapeutic planning, since any kind of pathology of any subject type can be tested at any time. Furthermore, it can provide a better understanding of functional anatomy, e.g. for the education of medical students.

The aim of this study was to analyze the precision of tibial cartilage morphometry, by using a fast, coronal water-excitation sequence with high spatial resolution, to compare the reproducibility of 3D thickness vs volume estimates, and to test the technique in patients with severe osteoarthritis. The tibiae of 8 healthy volunteers and 3 patients selected for total knee arthroplasty were imaged repeatedly with a water-excitation sequence (image time 6 h 19 min, resolution 1.2 x 0.31 x 0.31 mm(3)), with the knee being repositioned between each replicate acquisition. After 3D reconstruction, the cartilage volume, the mean, and the maximal tibial cartilage thickness were determined by 3D Euclidean distance transformation. In the volunteers, the precision of the volume measurements was 2.3 % (CV%) in the medial and 2.6 % in the lateral tibia. The reproducibility of the mean cartilage thickness was similar (2.6 and 2.5 %, respectively), and that of the maximal thickness lower (6.5 and 4.4 %). The patients showed a considerable reduction in volume and thickness, the precision being comparable with that in the volunteers. We find that, using a new imaging protocol and computational algorithm, it is possible to determine tibial cartilage morphometry with high precision in healthy individuals as well as in patients with osteoarthritis.

We assessed the anatomy of the anterior cruciate ligament (ACL) and femoral intercondylar notch on cryosections from one cadaveric knee specimen in the coronal oblique plane oriented parallel to the intercondylar roof. We determined the course of the ACL, the widths of the cruciate ligaments at intersection, and the intercondylar notch configuration on coronal oblique plane magnetic resonance images in 51 adult cruciate ligament-intact knees (25 women, 26 men; age range, 16 to 47 years). The intercondylar notch widths were measured at the notch entrance, at the intersection of the ACL and posterior cruciate ligament (PCL), and at the notch outlet. In the coronal oblique plane, the ACL exhibited a diagonal course from the central and medial part of the anterior intercondylar area of the tibia distally, across the lateral third of the intercondylar notch, to the intercondylar surface of the lateral femoral condyle proximally. At the cruciate ligament intersection, the absolute widths of the ACLs measured on average 6.1+/-1.1 mm in men and 5.2+/-1.0 mm in women representing 31.9% and 31.1% of the ACL/central intercondylar notch width ratios. The absolute widths of the PCLs measured on average 9.6+/-1.3 mm in men and 8.5+/-1.3 mm in women representing 50.4% and 51.4% of PCL/central intercondylar notch width ratios. On average for both groups, men and women, the absolute widths of the PCLs were significantly larger than the absolute widths of the ACLs. However, the relative widths of the cruciate ligaments with respect to corresponding intercondylar notch widths were not significantly different. In the coronal oblique plane, the intercondylar notch widths showed on average a significant decrease from posterior to intersection and from intersection to anterior. At notch outlet, the mean notch width measured 21.4 mm in men and 18.5 mm in women. At intersection, the mean notch width measured 19.1 mm in men and 16.6 mm in women. At notch entrance, the notch width measured 14.6+/-1.8 mm in men and 12.7+/-2.1 mm in women. We recommend magnetic resonance tomography of the knee in the coronal oblique plane oriented parallel to the intercondylar roof as the imaging modality of choice to visualize accurately the anatomic diagonal course of the ACL and its relation to the intercondylar notch and posterior cruciate ligament complex.

The objective of this work was to characterize tibial plateau coverage and morphometric differences of the medial (MM) and lateral meniscus (LM) in a male reference cohort using three-dimensional imaging. Coronal multiplanar reconstructions of a sagittal double-echo steady state with water excitation magnetic resonance sequence (slice thickness: 1.5 mm, and in-plane resolution: 0.37 × 0.70 mm) were analyzed in 47 male participants without symptoms, signs or risk factors of knee osteoarthritis of the reference cohort of the Osteoarthritis Initiative. The medial and lateral tibial (LT) plateau cartilage area and the tibial, femoral and external surfaces of the MM and LM were manually segmented throughout the entire knee. This process was assisted by parallel inspection of a coronal intermediately weighted turbo spin echo sequence. Measures of tibial coverage, meniscus size, and meniscus position were computed three-dimensionally for the total menisci, the body, and the anterior and the posterior horn. The LM was found to cover a significantly greater (p < 0.001) proportion of the LT plateau (59 ± 6.8%) than the MM of the medial plateau (50 ± 5.5%). Whereas the volume of both menisci was similar (2.444 vs. 2.438 ml; p = 0.92), the LM displayed larger tibial and femoral surface areas (p < 0.05) and a smaller maximal (7.2 ± 1.0 vs. 7.7 ± 1.1 mm; p < 0.01) and mean thickness (2.7 ± 0.3 vs. 2.8 ± 0.3 mm; p < 0.001) than the medial one. Also, the LM displayed less (physiological) extrusion than the medial one. These data may guide strategies for meniscal tissue engineering and transplantation aiming to restore normal joint conditions. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]