Features of the popliteal lymph nodes seen on musculoskeletal MRI in a Western population

To asses the features and explore the clinical relevance of popliteal lymph nodes (PLNs) detected on MRI examination for different pathologies of the knee. A total of 150 knee MRIs, which were conducted for various indications, were retrospectively collected from the Picture Archiving and Communication System. Imaging planes in at least two orthogonal planes were mandatory, with a field of view extending 15 cm cranial from the joint space. The localization of the PLN was determined by measuring the distance of the lowest border of the PLN to the lowest border of the lateral femoral condyle. Clinical diagnosis was obtained from radiology reports and a statistician performed the statistical analysis. The patients were 70 males [mean age 36.6 years (range: 5-72 years)] and 80 females [mean age 41.1 years (range: 9-76 years)]. In 36.7% of the patients, a PLN was visible. The number of PLNs was negatively associated with age (p < 0.001). The mean number of PLNs was 0.5 PLN per patient. The mean length, height, and width were respectively: 0.57 cm (SD = 0.15), 0.84 cm (SD = 0.26), and 0.71 cm (SD = 0.23). The mean location was 5.8 cm (SD = 1.61). No association was found between the presence of PLNs and internal derangement, inflammation, or cancer (p = 0.368). PLNs appearance is age related, with a higher frequency at a young age. The presence of the PLNs showed no relation to a specific clinical situatio

Skin marker-based versus bone morphology-based coordinate systems of the hindfoot and forefoot

Segment coordinate systems (CSs) of marker-based multi-segment foot models are used to measure foot kinematics, however their relationship to the underlying bony anatomy is barely studied. The aim of this study was to compare marker-based CSs (MCSs) with bone morphology-based CSs (BCSs) for the hindfoot and forefoot. Markers were placed on the right foot of fifteen healthy adults according to the Oxford, Rizzoli and Amsterdam Foot Model (OFM, RFM and AFM, respectively). A CT scan was made while the foot was loaded in a simulated weight-bearing device. BCSs were based on axes of inertia. The orientation difference between BCSs and MCSs was quantified in helical and 3D Euler angles. To determine whether the marker models were able to capture inter-subject variability in bone poses, linear regressions were performed. Compared to the hindfoot BCS, all MCSs were more toward plantar flexion and internal rotation, and RFM was also oriented toward more inversion. Compared to the forefoot BCS, OFM and RFM were oriented more toward dorsal and plantar flexion, respectively, and internal rotation, while AFM was not statistically different in the sagittal and transverse plane. In the frontal plane, OFM was more toward eversion and RFM and AFM more toward inversion compared to BCS. Inter-subject bone pose variability was captured with RFM and AFM in most planes of the hindfoot and forefoot, while this variability was not captured by OFM. When interpreting multi-segment foot model data it is important to realize that MCSs and BCSs do not always align.</p

The impact of using three-dimensional digital models of human embryos in the biomedical curriculum

Background: Knowledge of embryonic development is essential to understand the positioning of organs in the human body. Unfortunately, (bio)medical students have to struggle with textbooks that use static, two-dimensional (2D) schematics to grasp the intricate three-dimensional (3D) morphogenesis of the developing human body. To facilitate embryology education on an understandable and scientific level, a 3D Atlas of Human Embryology (3D Atlas) was created (Science, 2016), encompassing 14 interactive 3D-PDFs of various stages of human embryonic development (freely available from http://www.3datlasofhumanembryology.com). This study examined whether the use of the 3D atlas has added educational value and improves the students learning experience. Methods: The 3D atlas was introduced and integrated in lectures and practical classes of an existing embryology course at our university for first year biomedical students. By means of a questionnaire the use of the 3D atlas was evaluated. The outcomes in written examinations was compared between cohorts that followed the course before and after integration of the 3D atlas. Results: Our results showed that the 3D Atlas significantly improves students’ understanding of human embryology, reflected in significant higher test scores for new students. Furthermore, the 3D atlas also significantly improved repeaters’ test scores. Conclusions: The results indicate that the3D Atlas of Human Embryology facilitates students’ learning experience as a resource to support embryology lectures. Students appreciated the use of the 3D atlas in practical classes and liked its interactive aspect. Interestingly, the students also appreciated the physical hand-painted embryological models that were used in addition to the digital 3D atlas during practical classes. The 3D Atlas of Human Embryology has proven to be a valuable resource in addition to the existing resources to teach the intricate developmental processes of human embryology, especially in a blended learning curriculum

A new bone-cutting approach for minimally invasive surgery

Aims: Resection of bone is performed in over 75% of all orthopaedic procedures and the electrically powered oscillating saw is commonly used to cut bone. Drawbacks are relatively large incisions and tissue damage due to overshooting often occur. Therefore, the goal of this study is to develop an improved bone-cutting system that has minimally invasive characteristics. Methods: A new reusable sawing system was designed that can be used in Minimally Invasive Surgery (MIS) consisting of a steerable wire passer and a tissue saving wire saw guide. The system was tested during surgery on a human cadaveric tibia and calcaneus. Results: A MIS steerable compliant Nitinol needle was built and successfully used in a cadaveric surgery to position the cutting wire around a tibia and calcaneus. A wire saw operating system was built that was successfully used to cut the tibia and calcaneus. Conclusion: A MIS bone-cutting system was successfully designed, manufactured and used in a cadaver study showing that safe minimally invasive bone-cutting is feasible for two bone types with minimal damage to the surrounding tissue. Design optimization is needed to stabilize the compliant Nitinol needle during wire saw positioning and to allow cutting of bones with smaller diameters.</p

The plantaris tendon and a potential role in mid-portion Achilles tendinopathy: an observational anatomical study

The source of pain and the background to the pain mechanisms associated with mid-portion Achilles tendinopathy have not yet been clarified. Intratendinous degenerative changes are most often addressed when present. However, it is questionable if degeneration of the tendon itself is the main cause of pain. Pain is often most prominent on the medial side, 2-7cm from the insertion onto the calcaneus. The medial location of the pain has been explained to be caused by enhanced stress on the calcaneal tendon due to hyperpronation. However, on this medial side the plantaris tendon is also located. It has been postulated that the plantaris tendon might play a role in these medially located symptoms. To our knowledge, the exact anatomy and relationship between the plantaris- and calcaneal tendon at the level of complaints have not been anatomically assessed. This was the purpose of our study. One-hundred and seven lower extremities were dissected. After opening the superficial fascia and paratendon, the plantaris tendon was bluntly released from the calcaneal tendon moving distally. The incidence of the plantaris tendon, its course, site of insertion and possible connections were documented. When with manual force the plantaris tendon could not be released, it was defined as a 'connection' with the calcaneal tendon. In all specimens a plantaris tendon was identified. Nine different sites of insertion were found, mostly medial and fan-shaped onto the calcaneus. In 11 specimens (10%) firm connections were found at the level of the calcaneal tendon mid-portion. Clinical and histological studies are needed to confirm the role of the plantaris tendon in mid-portion Achilles tendinopath

Study on the three-dimensional orientation of the posterior facet of the subtalar joint using simulated weight-bearing CT

The purpose of this study was to describe the normal 3D orientation and shape of the subtalar calcaneal posterior facet. This is not adequately described in current literature. In a supine position both feet of 20 healthy subjects were imaged in a simulated weight-bearing CT. A cylinder and plane were fitted to the posterior facet of the surface model. The orientation of both shapes was expressed by two angles in (1) the CT-based coordinate system with the axis of the foot aligned with the sagittal axis and (2) a coordinate system based on the geometric principal axes of the subject's calcaneus. The subtalar vertical angle was determined in the intersection in three different coronal planes of the cylinder. The cylinder's axis oriented from supero-postero-laterally to infero-antero-medially. The plane's normal directed supero-antero-medially in the CT-based coordinate system, and supero-antero-laterally in the other coordinate system. The subtalar vertical angle was significantly different (p < 0.001) between the three defined coronal planes and increased from anterior to posterior. The mean diameter of the fitted cylinder was 42.0 ± 7.7 mm and the root mean square error was 0.5 ± 0.1 mm. The posterior facet can be modelled as a segment of a cylinder with a supero-postero-lateral to infero-antero-medial orientation. The morphometry of the posterior facet in a healthy population serves as a reference in identifying abnormal subtalar joint morphology. More generally this study shows the need to include the full 3D morphology in assessing the orientation of the subtalar posterior facet. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1–8, 2018

Skin marker-based versus bone morphology-based coordinate systems of the hindfoot and forefoot

Segment coordinate systems (CSs) of marker-based multi-segment foot models are used to measure foot kinematics, however their relationship to the underlying bony anatomy is barely studied. The aim of this study was to compare marker-based CSs (MCSs) with bone morphology-based CSs (BCSs) for the hindfoot and forefoot. Markers were placed on the right foot of fifteen healthy adults according to the Oxford, Rizzoli and Amsterdam Foot Model (OFM, RFM and AFM, respectively). A CT scan was made while the foot was loaded in a simulated weight-bearing device. BCSs were based on axes of inertia. The orientation difference between BCSs and MCSs was quantified in helical and 3D Euler angles. To determine whether the marker models were able to capture inter-subject variability in bone poses, linear regressions were performed. Compared to the hindfoot BCS, all MCSs were more toward plantar flexion and internal rotation, and RFM was also oriented toward more inversion. Compared to the forefoot BCS, OFM and RFM were oriented more toward dorsal and plantar flexion, respectively, and internal rotation, while AFM was not statistically different in the sagittal and transverse plane. In the frontal plane, OFM was more toward eversion and RFM and AFM more toward inversion compared to BCS. Inter-subject bone pose variability was captured with RFM and AFM in most planes of the hindfoot and forefoot, while this variability was not captured by OFM. When interpreting multi-segment foot model data it is important to realize that MCSs and BCSs do not always align.</p

A new bone-cutting approach for minimally invasive surgery

Aims: Resection of bone is performed in over 75% of all orthopaedic procedures and the electrically powered oscillating saw is commonly used to cut bone. Drawbacks are relatively large incisions and tissue damage due to overshooting often occur. Therefore, the goal of this study is to develop an improved bone-cutting system that has minimally invasive characteristics. Methods: A new reusable sawing system was designed that can be used in Minimally Invasive Surgery (MIS) consisting of a steerable wire passer and a tissue saving wire saw guide. The system was tested during surgery on a human cadaveric tibia and calcaneus. Results: A MIS steerable compliant Nitinol needle was built and successfully used in a cadaveric surgery to position the cutting wire around a tibia and calcaneus. A wire saw operating system was built that was successfully used to cut the tibia and calcaneus. Conclusion: A MIS bone-cutting system was successfully designed, manufactured and used in a cadaver study showing that safe minimally invasive bone-cutting is feasible for two bone types with minimal damage to the surrounding tissue. Design optimization is needed to stabilize the compliant Nitinol needle during wire saw positioning and to allow cutting of bones with smaller diameters.Medical Instruments & Bio-Inspired Technolog

Difference in orientation of the talar articular facets between healthy ankle joints and ankle joints with chronic instability

Since both the talocrural and subtalar joints can be involved in chronic ankle instability, the present study assessed the talar morphology as this bone is the key player between both joint levels. The 3D orientation and curvature of the superior and the posteroinferior facet between subjects with chronic ankle instability and healthy controls were compared. Hereto, the talus was segmented in the computed tomography images of a control group and a chronic ankle instability group, after which they were reconstructed to 3D surface models. A cylinder was fitted to the subchondral articulating surfaces. The axis of a cylinder represented the facet orientation, which was expressed by an inclination and deviation angle in a coordinate system based on the cylinder of the superior talar facet and the geometric principal axes of the subject's talus. The curvature of the surface was expressed as the radius of the cylinder. The results demonstrated no significant differences in the radius or deviation angle. However, the inclination angle of the posteroinferior talar facet was significantly more plantarly orientated (by 3.5°) in the chronic instability group (14.7 ± 3.1°) compared to the control group (11.2 ± 4.9°) (p < 0.05). In the coronal plane this corresponds to a valgus orientation of the posteroinferior talar facet relative to the talar dome. In conclusion, a more plantarly and valgus orientated posteroinferior talar facet may be associated to chronic ankle instability

The Mechanical Functionality of the EXO-L Ankle Brace: Assessment With a 3-Dimensional Computed Tomography Stress Test

A new type of ankle brace (EXO-L) has recently been introduced. It is designed to limit the motion of most sprains without limiting other motions and to overcome problems such as skin irritation associated with taping or poor fit in the sports shoe. To evaluate the claimed functionality of the new ankle brace in limiting only the motion of combined inversion and plantar flexion. Controlled laboratory study. In 12 patients who received and used the new ankle brace, the mobility of the joints was measured with a highly accurate and objective in vivo 3-dimensional computed tomography (3D CT) stress test. Primary outcomes were the ranges of motion as expressed by helical axis rotations without and with the ankle brace between the following extreme positions: dorsiflexion to plantar flexion, and combined eversion and dorsiflexion to combined inversion and plantar flexion. Rotations were acquired for both talocrural and subtalar joints. A paired Student t test was performed to test the significance of the differences between the 2 conditions (P ≤ .05). The use of the ankle brace significantly restricted the rotation of motion from combined eversion and dorsiflexion to combined inversion and plantar flexion in both the talocrural (P = .004) and subtalar joints (P < .001). No significant differences were found in both joints for the motion from dorsiflexion to plantar flexion. The 3D CT stress test confirmed that under static and passive testing conditions, the new ankle brace limits the inversion-plantar flexion motion that is responsible for most ankle sprains without limiting plantar flexion or dorsiflexion. This test demonstrated its use in the objective evaluation of brace