Lateral Supporting Structures Research Articles

Wing serial homologues and the diversification of insect outgrowths: insights from the pupae of scarab beetles.

Modification of serially homologous structures is a common avenue towards functional innovation in developmental evolution, yet ancestral affinities among serial homologues may be obscured as structure-specific modifications accumulate over time. We sought to assess the degree of homology to wings of three types of body wall projections commonly observed in scarab beetles: (i) the dorsomedial support structures found on the second and third thoracic segments of pupae, (ii) the abdominal support structures found bilaterally in most abdominal segments of pupae, and (iii) the prothoracic horns which depending on species and sex may be restricted to pupae or also found in adults. We functionally investigated 14 genes within, as well as two genes outside, the canonical wing gene regulatory network to compare and contrast their role in the formation of each of the three presumed wing serial homologues. We found 11 of 14 wing genes to be functionally required for the proper formation of lateral and dorsal support structures, respectively, and nine for the formation of prothoracic horns. At the same time, we document multiple instances of divergence in gene function across our focal structures. Collectively, our results support the hypothesis that dorsal and lateral support structures as well as prothoracic horns share a developmental origin with insect wings. Our findings suggest that the morphological and underlying gene regulatory diversification of wing serial homologues across species, life stages and segments has contributed significantly to the extraordinary diversity of arthropod appendages and outgrowths.

Lateral support structure for 600 mm primary mirror of laser communication

The main function of the laser communication large-caliber ground optical transceiver is to establish a communication link with the satellite to realize data transmission between the satellite and the ground station. The 600 mm microcrystalline primary mirror of one laser communication station is heavy, and its working angle changes constantly. In order to decrease the mirror surface error, the support system not only has a 9-pose axial support structure but also simultaneously balances the radial component of gravity of the primary mirror at its working angle by using a radial support structure. Flexible lateral support structures have large size and stress, so it is not suit for the mirror that works in a wide range of rotation. The paper researches the lateral support structure with a mercury band and central shaft, and analyses the impact of mercury band parameters on the surface error. The designed lateral structure has small size and improves the surface quality of the mirror. The measured values of PV and RMS are smaller than λ/5 and λ/37, respectively. These result shows that the designed lateral support structure reaches the design purpose and satisfies the requirements.

The naked capitellum: a surgeon's guide to intraoperative identification of posterolateral rotatory instability

This study's purpose was to provide a reproducible way for surgeons to intraoperatively assess the elbow's lateral ulnar collateral ligament origin and determine whether there is posterolateral rotatory instability (PLRI) despite an intact common extensor origin (CEO). We hypothesized that we could re-create clinically relevant disruption of lateral supporting structures despite an intact CEO and illustrate progressive elbow PLRI. The relationship of the lateral capsule to the capitellum articular surface was noted in 8 cadaveric upper extremities. The lateral capsule and extensor origin were sequentially sectioned at 4 stages: intact, release to the lateral epicondyle, release of the posterior capsular insertion, and release of the CEO. Posterior and lateral translation of the radial head (RH) relative to the capitellum was measured with the forearm in extension and supination. The average specimen age was 78.9 years. The lateral capsule originated within 1 to 2 mm of the capitellum articular surface. Lateral capsular sectioning to the 6-o'clock position of the lateral epicondyle created an unstable elbow with posterior and lateral RH translation. Sequential sectioning of the posterior capsular insertion created significant additional RH translation posteriorly (P < .05). With release of the capsule and the extensor origin, the elbow was grossly unstable. The elbow's lateral capsuloligamentous complex plays an important role in preventing PLRI. Larger degrees of elbow laxity are associated with further peel back of the capsuloligamentous complex despite an intact CEO. The surgeon must retract the extensor origin intraoperatively to assess for lateral ulnar collateral ligament and/or lateral capsule disruption to prevent a missed case of PLRI.

Snowboarder's fracture caused by a wakeboarding injury: a case report

Objective The purpose of this case report is to describe the clinical presentation of a patient who had a lateral talar process fracture due to a wakeboarding injury. Clinical Features A 29-year-old male patient sustained a left ankle injury when the front edge of his wakeboard became immersed in the water. As he fell forward, his foot remained attached to the board, leading to inversion and dorsiflexion stress of the ankle. He presented to a chiropractic clinic with diffuse ankle swelling, tenderness, and pain at the distal aspect of the lateral malleolus. Mild ligamentous laxity of the lateral supporting structures was observed during the physical examination. Intervention and Outcome Static and stress radiographs of the left ankle demonstrated a small (McCrory-Bladin type 1) lateral talar process fracture without evidence of gross instability. The patient was referred to a local orthopedic medical specialist for immobilization of the ankle. The patient was treated conservatively with an air cast walking boot for 2 weeks (non–weight-bearing) followed by a 2-week period of partial weight-bearing. At 6 weeks following the injury, a repeated radiographic examination demonstrated complete healing of the fracture. The patient reported minimal tenderness and normal ankle function. Conclusion Because of the similar mechanism of injury to those sustained in snowboarding, this case demonstrates the need for increased awareness of lateral process fractures in wakeboarders.

Knee: Ligamentous Injuries of the Knee

Injuries of the knee causing ligament failure are common, especially in amateur and professional athletes. These injuries affect the anterior and posterior cruciate ligaments, the medial collateral ligamentous complex, or the lateral supporting structures, or combinations of these ligaments. The presence of marrow edema on MR images obtained shortly after the injury provide an important clue to accurate diagnosis and to the mechanism of the traumatic event. In this presentation, the effects of external and internal forces applied to the knee will be studied. The modifications in the distribution of the marrow edema caused by such factors as impaction/distraction, flexion, rotation, hyperextension, and translation will be illustrated. Stages of ligament injury during specific traumatic mechanisms will be discussed, and examples of some of the 010 most important mechanisms of knee injury will be shown.

Orthotic design and foot impression procedures to control foot alignment

The traditional theory on subtalar joint neutral position and intrinsic foot deformities for the evaluation and treatment of foot and ankle disorders has been the basis for foot orthotics for many years. Although clinical evaluations have suggested a relationship between subtalar pronation and a variety of lower limb problems, such as shin splints and anterior knee pain, recent research has raised serious concerns about the reliability and validity of the assessment and intervention methods. Results of recent studies in foot biomechanics suggest that the orthosis design to control foot alignment should stabilise the medial apical bony structure of the arch to control the first ray mobility and transmit load through the lateral support structures of the foot, locking the calcaneocuboid joint and decreasing strain in the plantar aponeurosis. The concept of "posting" according to a measured foot deformity is de-emphasised. Reliable foot impression procedures are required to provide appropriate orthotic design and thus management. A prone lying position manipulated foot impression method using polycaprolactone based low temperature thermoplastic material was introduced. Ten (10) subjects were recruited to participate in the reliability tests, which were conducted by 2 orthotists specialized in foot orthotics. Results showed high intrarater and interrater reliability of the measured forefoot width and the navicular height. The reliability of the forefoot-rearfoot relationship was demonstrated by the small variance of the root mean square calculation. Subsequently orthotic intervention can be done in a more consistent manner.

The influence of iliotibial tract on patellar tracking.

Thirty patients with 49 snapping hips and patellar malalignment underwent surgical release of the iliotibial tract contracture over the trochanteric area. Minimal follow-up was 2 years (average 4.6 years, range: 2-9 years). Eight patients underwent computed tomography (CT) preoperatively and 1 month postoperatively to investigate the patellar location in the patellofemoral articulation with knee bending at 0 degrees, 20 degrees, 45 degrees, 60 degrees, and 90 degrees. Significant improvements in the congruence angle and lateral patellofemoral angle were noted on Merchant radiograph for all knees (P<.01). On CT, at 20 degrees and 45 degrees knee bending, all congruence, lateral patellofemoral, and patellar tilt angles significantly improved postoperatively in 8 knees (P<.01). Iliotibial tract affects patellar tracking and dominates lateral patellar supporting structures.

Pathogenesis of the Segond fracture: anatomic and MR imaging evidence of an iliotibial tract or anterior oblique band avulsion.

To demonstrate the normal anatomy of the stabilizing structures of the lateral aspect of the knee and to investigate pathogenesis of the Segond fracture, with emphasis on the iliotibial tract (ITT) and anterior oblique band (AOB) of the fibular collateral ligament. Dissection of the region of the AOB, ITT, and lateral capsular ligament was performed in three cadaveric knees, with placement of gadopentetate dimeglumine-filled tubes along their course and tibial insertions. These knees, in addition to three nondissected knees, were studied with magnetic resonance (MR) imaging by using standard and specialized oblique planes. Specimen sectioning provided anatomic correlation. Retrospective review of radiographs and MR images in 17 patients with acute Segond fractures was performed, and the relationship between the fragment and the demonstrated lateral supporting structures of the knee was noted. Anatomic dissection and MR imaging of the cadaveric knees demonstrated a broad tibial insertion of the ITT, with fibers extending posterior to the Gerdy tubercle. A firm band of tissue, the AOB, extended from the fibular collateral ligament to the midportion of the lateral tibia, the typical site of a Segond fracture. The lateral capsular ligament proved to be a mere thickening of the capsule, inserting at the lateral tibia. Clinical analysis of acute Segond fractures confirmed the frequent attachment of the ITT and AOB to the avulsed fragment. Anatomic and clinical findings suggest that fibers of the ITT and AOB are important factors in the pathogenesis of the Segond fracture.

KSTAR magnet structure design

The Korea Superconducting Tokamak Advanced Research (KSTAR) device is a steady-state-capable experimental fusion device with a fully superconducting magnet system, including toroidal field (TF) coils, central solenoid (CS) coils, and poloidal field (PF) coils. The major design consideration of the magnet system is to meet the KSTAR mission with plasma current of 2 MA and toroidal field of 3.5 T at the major radius 1.8 m and z=0. The preliminary analyses show that the magnet structure design has mechanical, electrical, and thermal stability during operation. The TF magnets have a wedged structure, including coil cases, inter-coil structures, and inter-octant joints. The CS and PF structures are designed to support the electromagnetic forces. To support the coil system against gravity and lateral loads, gravity support and lateral load structures are designed.

Lateral Ligamentous Instability

Summary: Acute and chronic elbow instability continues to be a vexing problem. The role of the lateral supporting structures in recurrent elbow dislocation has been recognized for more than 30 years; however, the condition of posterolateral rotatory instability of the elbow has only recently been described. Unlike medial collateral ligament insufficiency, virtually all cases of chronic lateral ligamentous instability are related to previous trauma. Recognition and appropriate treatment of acute lateral ligament injuries may help prevent chronic elbow instability. Reconstruction of the lateral ulnar collateral ligament is an effective treatment for recurrent elbow dislocation and posterolateral rotatory instability. The diagnosis, indications, surgical techniques, and postoperative care of patients with lateral ligamentous instability are presented here.

Anatomic and biomechanical aspects of pie crusting posterolateral structures for valgus deformity correction in total knee arthroplasty: A cadaveric study

Correction of valgus deformity during total knee arthroplasty is usually carried out by releasing lateral supporting structures from the femoral side of the joint. A new technique has been advocated that involves multiple stabs of the scalpel blade or pie crusting of the posterolateral corner. It is the hypothesis of this study that the correction achieved by using this technique occurs when the lateral collateral ligament is effectively released and that the common peroneal nerve may be at risk. Using a cadaveric model with 6 knees tested, significant differences were determined between 2 separate pie crusting steps as well as between releasing the lateral collateral ligament and popliteus tendons. Anatomic dissection studies also showed that in full extension the peroneal nerve may be less than the depth of a number 1 1 blade (16 mm) from the posterolateral corner, and the nerve may be at risk during this technique. These results show that major deformity correction obtained using the pie crusting technique is probably through effective release of the lateral collateral ligament.

Flexion-extension joint gap changes after lateral structure release for valgus deformity correction in total knee arthroplasty: A cadaveric study

At the time of total knee arthroplasty, the surgeon generally corrects excessive valgus knee alignment to anatomic valgus through release of lateral supporting structures. This study used a Cadaveric model to i) study the amount of correction achieved with each release step in 2 sequences of lateral release, ii) compare the amount of release in extension versus flexion, and iii) measure any associated rotational changes of the tibia. Six fresh-frozen Cadaveric knees were used to test the amount of change into varus after sectioning the iliotibial band (ITB), the popliteus tendon (Pop), the lateral collateral ligament (LCL), and the tendon of the lateral head of the gastrocnemius (LG). This sequence was then compared with a second sequence in another 6 cadavers as follows: LCL, Pop, ITB, and LG. The amount of valgus correction was tested in 90°, 45° flexion, and full extension. At each flexion angle, the corresponding releases were assessed with the tibia oriented vertically under its own weight, under tibial distraction with equal support from the lateral and medial soft tissues, and under a maximal varus deforming stress. Results showed that complete lateral structure release provides limited correction into a varus direction with a balanced distracted soft tissue gap or extension space (8.9° with the LG released), and the lateral aspect of the flexion gap opens more than the extension gap (8.9° compared with 18.1° in flexion). Early LCL release provided a more uniform release of the joint gap, and rotational changes were variable, tending toward external rotation of the tibia (6.0° in full extension with release of the LCL). We suggest that when severe valgus deformities are present, the LCL should be considered first for release and the Pop and ITB be used to grade the release.

The influence of medial and lateral placement of orthotic wedges on loading of the plantar aponeurosis.

Repetitive trauma and overuse of the plantar aponeurosis are believed to be causal factors of plantar fasciitis. Therefore, it is important to know how an orthosis influences loading of the plantar aponeurosis. The aim of this study was to quantify strain in the plantar aponeurosis in cadaveric feet with the use of various combinations of orthotic wedges. An in vitro test that simulated static stance was used to determine the loading characteristics of the plantar aponeurosis. A differential variable reluctance transducer was operatively implanted into the plantar aponeurosis of nine fresh-frozen cadaveric lower limbs. Each specimen was mounted in an electromechanical testing machine that applied an axial load of as much as 900 newtons to the tibia. Eight different combinations of test conditions, in which wedges (each with a 6-degree incline) were or were not positioned under the medial and lateral aspects of the forefoot and hindfoot, were evaluated, with the plantigrade foot used as a neutral control. Each of the test conditions that involved a wedge under the forefoot resulted in strain that was significantly different from that in the neutral control. A wedge under the lateral aspect of the forefoot decreased strain in the plantar aponeurosis, and a wedge under the medial aspect increased strain (p < 0.05). The test conditions that involved a wedge under the hindfoot but not under the forefoot resulted in strains that were not significantly different from those in the neutral control (p > 0.05). A wedge under the lateral aspect of the forefoot transmits loads through the lateral support structures of the foot, locking the calcaneocuboid joint and decreasing strain in the plantar aponeurosis. A wedge under the medial aspect of the forefoot transmits loads through the medial support structures of the foot, which produces a truss-like action that increases strain in the plantar aponeurosis.

MEDIAL AND LATERAL SUPPORTING STRUCTURES OF THE KNEE: Normal MR Imaging Anatomy and Pathologic Findings

The supporting structures of the knee can be divided into several layers: fascial boundaries, the collateral ligaments and tendons, and the joint capsule. MR imaging's ability to demonstrate these findings has helped to validate this anatomic concept. An appreciation for the organization of the medial and lateral compartments facilitates MR imaging interpretation.

Talar Shift

An effort was made to evaluate the importance of the supporting medial, lateral, and posterior ankle structures in preventing talar shift. A series of fresh autopsy specimen ankles were subjected to manual mediolateral and anteroposterior stressing of the talus as intact specimens and after deletion of credited stabilizing structures. The fibula and attached ligaments were major factors in preventing talar shift, both mediolaterally and anteriorly. The lateral supporting structures were also noted to securely stabilize the talus against posterior subluxation in the absence of the posterior and medial malleoli.

Posterior Instability of the Talus: An Anatomic Evaluation

A cadaver study was conducted to evaluate the role of the posterior tibial margin or posterior malleolus, as well as medial and lateral supporting structures, in providing posterior stability for the talus. Posterior malleolar fractures consisting of approximately 30%, 40%, and 50% of the articular margin on the lateral radiograph were created in specimens that were then subjected to posterior stressing. No posterior talar subluxation was noted in any specimen. Repeat stressing following removal of the medial malleolus again revealed no subluxation in any specimen. The lateral supporting structures, primarily the posterior fibulotalar and fibulocalcaneal ligaments, appeared to be the key structures providing posterior talar stability. If the fibula is stable in an anatomic position, feared posterior instability of the talus would not appear to be an indication for internal fixation of posterior malleolar fractures.

Acute straight lateral instability of the knee.

Although ligamentous injuries of the knee joint represent a common orthopaedic problem, damage to the lateral supporting structures is a relatively rare occurrence.

???Normal??? Talar Tilt Angle

A study to determine the degree of normal talar tilt in individuals with no history of ankle injuries was performed on 404 ankles of 202 midshipmen at the U.S. Naval Academy. Manual inversion stress roentgenograms were used to test this group of young healthy adults, most of whom were males. Of the 404 ankles tested, only 39 (9.7%) had any measurable talar tilt and only 7 ankles (1.7%) had a tilt over 5 degrees. Normal talar tilt does not range to 23 degrees. A normal ankle in a healthy young adult with no history of trauma has a small probability of having any talar tilt. When stress roentgenograms are used to evaluate a fresh lateral ankle ligament sprain in this type of individual, there is a very high probability that talar tilt over 5 degrees would represent significant injury to one or more of the lateral supporting structures.