An ethmoid exposure (os planum) in the orbit of Indri indri (Primates, Lemuriformes).

In 6 of 17 skulls of Indri indri retaining distinct sutures in the medial orbital wall, a small separate bony element intervenes between the frontal and the maxillolacrimal suture. This element is demonstrably continuous with the ethmoid on one such skull. The occurrence of an ethmoid exposure in the orbit of Indri suggests that this trait is not a simple function of orbital size and convergence. Since such an exposure is found in non-cheirogaleine lemuriforms, its distribution provides no support for the hyothesis that lorises and galagos are derived from cheirogaleines.     

Glued fixation of split-skin graft to the bony orbit following exenteration

A technique is described to fix a split-skin graft to the bony orbit with a new homologous fibrin adhesive system. This shortens the time between the exenteration and the fitting of an epithesis to the bony orbit as compared with the granulation technique or fitting the graft with a prolonged pressure bandage. The advantages and risks connected to the glue system are discussed.     

Can markers injected into a single-loop anterior cruciate ligament graft define the axes of the tibial and femoral tunnels? A cadaveric study using roentgen stereophotogrammetric analysis

Lengthening of a soft-tissue anterior cruciate ligament (ACL) graft construct over time, which leads to an increase in anterior laxity following ACL reconstruction, can result from relative motions between the graft and fixation devices and between the fixation devices and bone. To determine these relative motions using Roentgen stereophotogrammetry (RSA), it is first necessary to identify the axes of the tibial and femoral tunnels. The purpose of this in vitro study was to determine the error in using markers injected into the portions of a soft-tissue tendon graft enclosed within the tibial and femoral tunnels to define the axes of these tunnels. Markers were injected into the tibia, femur, and graft in six cadaveric legs the knees of which were reconstructed with single-loop tibialis grafts. The axes of the tunnels were defined by marker pairs that were injected into the bones on lines parallel to the walls of the tibial and femoral tunnels (i.e., standard). By using marker pairs injected into the portions of the graft enclosed within the tibial and femoral tunnels and the marker pairs aligned with the tunnel axes, the directions of vectors were determined by using RSA, while a 150 N anterior force was transmitted at the knee. The average and standard deviations of the angle between the two vectors were 5.5+/-3.3 deg. This angle translates into an average error and standard deviation of the error in lengthening quantities (i.e., relative motions along the tunnel axes) at the sites of fixation of (0.6+/-0.8)%. Identifying the axes of the tunnels by using marker pairs in the graft rather than marker pairs in the walls of the tunnels will shorten the surgical procedure by eliminating the specialized tools and time required to insert marker pairs in the tunnel walls and will simplify the data analysis in in vivo studies.     

Combined conchal cartilage-ethmoid bone grafts in nasal surgery

Septal cartilage grafts are frequently required in rhinoplasties and nasal reconstructions. Unfortunately, sufficient septum is not always available for graft purposes. Conchal cartilage can serve as a substitute, but its usefulness is limited because of its soft, elastic nature. Applying thin sheets of pliable ethmoid bone to conchal cartilage gives the cartilage greater strength and, at the same time, allows it to retain some flexibility. This article examines the role of combined conchal cartilage-ethmoid bone grafts in nasal surgery. These grafts are simple to construct and are versatile in their application. By maintaining a free cartilage edge, they are readily sutured into place. The results seem to last long term.     

The role of gap junctions in patterning of the chick limb bud

The role of gap junctional communication during patterning of the chick limb has been investigated. Affinity-purified antibodies raised against rat liver gap junctional proteins were used to block communication between limb mesenchyme cells. Co-injection of the antibodies and Lucifer yellow into mesenchyme cultures demonstrated that communication was inhibited almost immediately. When antibodies were loaded into mesenchyme tissue by DMSO permeabilization, [3H]nucleotide transfer was prevented for at least 16 h. Polarizing region tissue from the posterior limb bud margin causes digit duplications when grafted to the anterior margin. Quail polarizing region cells were loaded with gap junction antibody and grafted into chick wing buds. The antibody had no effect on growth or survival of the grafted cells. As very few polarizing region cells are required to initiate duplications, the number of polarizing region cells in the grafts was reduced by diluting 1:9 with anterior mesenchyme tissue. When either polarizing region or anterior mesenchyme tissue in the graft was loaded separately with antibody, there was little effect on respecification of the digit pattern. However, loading both tissues in the graft caused a significant decrease in duplications. This indicates that a major role of gap junctions in limb patterning may be to enable polarizing region cells to communicate directly with adjacent anterior mesenchyme. A role for gap junctional communication between anterior mesenchyme cells cannot be excluded. The results are discussed in relation to the role of retinoic acid as a putative morphogen.     

Frontal cranioplasty: risk factors and choice of cranial vault reconstructive material

A study of patients with large cranial defects involving the frontal bone, frontal sinus, nose, and orbit does not support the contention that there is a clear superiority of reconstructive material despite a history of previous bone infection. No patient with an isolated cranial reconstruction experienced an infection despite location in the area of the frontal sinus or the use of acrylic material. All patients experiencing infection underwent simultaneous reconstruction of the frontal cranium and nose and three- or four-wall reconstruction of the orbit, where the frontal sinus had previously been eliminated and where a previous bone infection had been present. Risk factors associated with cranioplasty were timing (p = 0.001) and cranial vault reconstruction in communication with previously infected ethmoid sinuses and the nose (p = 0.03). A history of previous bone infection suggests increased risk (p = 0.15). The choice of reconstructive material was not significant, although acrylic cranioplasties did not experience the complications expected from a review of the literature.     

Roentgen stereophotogrammetric analysis methods for determining ten causes of lengthening of a soft-tissue anterior cruciate ligament graft construct

There are many causes of lengthening of an anterior cruciate ligament soft-tissue graft construct (i.e., graft+fixation devices+bone), which can lead to an increase in anterior laxity. These causes can be due to plastic deformation andor an increase in elastic deformation. The purposes of this in vitro study were (1) to develop the methods to quantify eight causes (four elastic and four plastic) associated with the tibial and femoral fixations using Roentgen stereophotogrammetric analysis (RSA) and to demonstrate the usefulness of these methods, (2) to assess how well an empirical relationship between an increase in length of the graft construct and an increase in anterior laxity predicts two causes (one elastic and one plastic) associated with the graft midsubstance, and (3) to determine the increase in anterior tare laxity (i.e., laxity under the application of a 30 N anterior tare force) before the graft force reaches zero. Markers were injected into the tibia, femur, and graft in six cadaveric legs whose knees were reconstructed with single-loop tibialis grafts. To satisfy the first objective, legs were subjected to 1500 cycles at 14 Hz of 150 N anterior force transmitted at the knee. Based on marker 3D coordinates, equations were developed for determining eight causes associated with the fixations. After 1500 load cycles, plastic deformation between the graft and WasherLoc tibial fixation was the greatest cause with an average of 0.8+/-0.5 mm followed by plastic deformation between the graft and cross-pin-type femoral fixation with an average of 0.5+/-0.1 mm. The elastic deformations between the graft and tibial fixation and between the graft and femoral fixation decreased averages of 0.3+/-0.3 mm and 0.2+/-0.1 mm, respectively. The remaining four causes associated with the fixations were close to 0. To satisfy the remaining two objectives, after cyclic loading, the graft was lengthened incrementally while the 30 N anterior tare laxity, 150 N anterior laxity, and graft tension were measured. The one plastic cause and one elastic cause associated with the graft midsubstance were predicted by the empirical relationships with random errors (i.e., precision) of 0.9 mm and 0.5 mm, respectively. The minimum increase in 30 N anterior tare laxity before the graft force reached zero was 5 mm. Hence, each of the eight causes of an increase in the 150 N anterior laxity associated with the fixations can be determined with RSA as long as the overall increase in the 30 N anterior tare laxity does not exceed 5 mm. However, predicting the two causes associated with the graft using empirical relationships is prone to large errors.     

Lengthening of a single-loop tibialis tendon graft construct after cyclic loading: a study using Roentgen stereophotogrammetric analysis

Although single-loop tibialis tendon allografts have increased in popularity owing to their many advantages over patellar tendon and double-loop hamstring tendon autografts, some percentage of the patient population do not have clinically stable knees following anterior cruciate ligament reconstruction with single-loop tibialis tendon allografts. Therefore, it would be advantageous to determine the causes of increased anterior laxity which ultimately must be traced to lengthening of the graft construct. One objective of this study was to demonstrate the feasibility of using Roentgen stereophotogrammetric analysis (RSA) to determine the causes of lengthening of a single-loop graft construct subjected to cyclic loading. A second objective was to determine which cause(s) contributes most to an increase in length of this graft construct. Radio-opaque markers were inserted into ten grafts to measure the lengthening at the sites of the tibial and femoral fixations and between the sites of fixation. Each graft was passed through a tibial tunnel in a calf tibia, looped around a rigid cross-pin, and fixed to the tibia with a Washerloc fixation device. The grafts were cyclically loaded for 225,000 cycles from 20 to 170 N. Prior to and at intervals during the cyclic loading, simultaneous radiographs were taken. RSA was used to determine the three-dimensional coordinates of the markers from which the lengthening at the sites of fixation and between the sites of fixation was computed at each interval. The sites of the femoral and tibial fixations were the largest contributors to the increase in length of the graft construct, with maximum average values of 0.68 and 0.55 mm, respectively, after 225,000 cycles. The graft substance between the sites of fixation contributed least to lengthening of the graft, with a maximum average value of 0.31 mm. Ninety percent of the maximum average values occurred before 100,000 cycles of loading for the largest contributors. RSA proved to be a useful method for measuring lengthening due to all three causes. Lengthening of the graft construct at the sites of both fixations is sufficiently large that the combined contributions may manifest as a clinically important increase in anterior laxity.     

Empirical relationship between lengthening an anterior cruciate ligament graft and increases in knee anterior laxity: a human cadaveric study

Lengthening of an anterior cruciate ligament (ACL) graft construct can occur as a result of lengthening at the sites of tibial and/or femoral fixation and manifests as an increase in anterior laxity. Although lengthening at the site of fixation has been measured for a variety of fixation devices, it is difficult to place these results in a clinical context because the mathematical relationship between lengthening of an ACL graft construct and anterior laxity is unknown. The purpose of our study was to determine empirically this relationship. Ten cadaveric knees were reconstructed with a double-looped tendon graft. With the knee in 25 degrees of flexion, the position of the proximal end of the graft inside the femoral tunnel was adjusted by moving the femoral fixation device until the anterior laxity at an applied anterior force of 134 N matched that of the intact knee. In random order, the graft construct was lengthened 1, 2, 3, 4, and 5 mm by moving the femoral fixation device distally along the femoral tunnel and anterior laxity was measured. The increase in the length of the graft construct was related to the increase in anterior laxity by a simple linear regression model. Lengthening the graft construct from 1 to 5 mm caused an equal increase in anterior laxity (slope=1.0 mmmm, r(2)=0.800, p<0.0001). Because an anterior laxity increase of 3 mm or greater in a reconstructed knee is considered unstable clinically and because many fixation devices in widespread use clinically allow 3 mm or greater of lengthening in in vitro tests, our empirical relationship indicates that lengthening at the site of fixation probably is an important cause of knee instability following ACL reconstructive surgery. Our empirical relation also indicates that an important criterion in the design of future fixation devices is that lengthening at the sites of fixation in in vitro tests should be limited to less than 3 mm.     

Hedgehog signaling is required for cranial neural crest morphogenesis and chondrogenesis at the midline in the zebrafish skull

Neural crest cells that form the vertebrate head skeleton migrate and interact with surrounding tissues to shape the skull, and defects in these processes underlie many human craniofacial syndromes. Signals at the midline play a crucial role in the development of the anterior neurocranium, which forms the ventral braincase and palate, and here we explore the role of Hedgehog (Hh) signaling in this process. Using sox10:egfp transgenics to follow neural crest cell movements in the living embryo, and vital dye labeling to generate a fate map, we show that distinct populations of neural crest form the two main cartilage elements of the larval anterior neurocranium: the paired trabeculae and the midline ethmoid. By analyzing zebrafish mutants that disrupt sonic hedgehog (shh) expression, we demonstrate that shh is required to specify the movements of progenitors of these elements at the midline, and to induce them to form cartilage. Treatments with cyclopamine, to block Hh signaling at different stages, suggest that although requirements in morphogenesis occur during neural crest migration beneath the brain, requirements in chondrogenesis occur later, as cells form separate trabecular and ethmoid condensations. Cell transplantations indicate that these also reflect different sources of Shh, one from the ventral neural tube that controls trabecular morphogenesis and one from the oral ectoderm that promotes chondrogenesis. Our results suggest a novel role for Shh in the movements of neural crest cells at the midline, as well as in their differentiation into cartilage, and help to explain why both skeletal fusions and palatal clefting are associated with the loss of Hh signaling in holoprosencephalic humans.     

A model of anterior cruciate ligament reconstructive surgery: A validation construct and computational insights

This study sought to develop a computational framework that emulates the anterior cruciate ligament reconstruction surgery using transtibial portal technique. The proposed model included the tibia–femoral and patella–femoral joints, articular cartilage and menisci. Key surgical parameters were incorporated including bone-patellar-tendon-bone graft excision and pre-tensioning, tunnel morphology, bone plugs, and bone plug fixation. Several simulation steps were parameterized to reflect the clinically reported surgical procedure. Our focus was to explore the intra-operative effects of variations in tunnel directions on the selected metrics of joint mechanics during Lachman and Anterior Drawer tests. A mathematical construct capable of transforming the limited and heterogeneous experimental and surgical data to evidence-based validation was adopted to ensure the viability of the finite element models. We found that the proposed models, subject to a variation in tunnel directions, resulted in simulation outputs that favor the reported experimental data of Lachman and Anterior Drawer tests under uncertainty. Simulation results for a population of three-dimensional tunnel orientations provided insights into the graft–tunnel contact mechanics and the spatial stress distribution in the graft, insights that have been anecdotally observed in prior experimental studies. The intraarticular graft tension was found to be higher than the estimated in tunnel graft force, and larger differences were found for the least inclined tunnels exhibiting higher contact pressures, transverse bending and twisting of the graft and Von-Mises stress at the graft–femoral tunnel interface. Conversely, tunnels with high inclination angles exhibited higher intraarticular graft tension and Von-Mises stress at the graft–tibial bone plug interface.     

A new genus, Leptomelanosoma, for the polynemid fish previously known as Polydactylus indicus (Shaw, 1804) and a redescription of the species

A new genus, Leptomelanosoma, is proposed for the polynemid fish, Polydactylus indicus (Shaw, 1804). The genus differs from all other genera in the family Polynemidae by the following combination of characters: anterior one-third of lower jaw with small teeth extending onto lateral surface, adjacent portion of lip poorly developed; ethmoid not covered dorsally by frontals; sphenotics visible dorsally between anterior margins of parietal and pterotic; upper and lower caudal fin lobes very long, filamentous; swimbladder with many appendages inserted into lateral walls of abdominal cavity; grayish-black body. The type species, Polydactylus indicus, is redescribed as Leptomelanosoma indicum. Received: September 19, 1999 / Revised: June 9, 2000 / Accepted: July 10, 2000     

Deformation of nasal septal cartilage during mastication

The cartilaginous nasal septum plays a major role in structural integrity and growth of the face, but its internal location has made physiologic study difficult. By surgically implanting transducers in 10 miniature pigs (Sus scrofa), we recorded in vivo strains generated in the nasal septum during mastication and masseter stimulation. The goals were (1) to determine whether the cartilage should be considered as a vertical strut supporting the nasal cavity and preventing its collapse, or as a damper of stresses generated during mastication and (2) to shed light on the overall pattern of snout deformation during mastication. Strains were recorded simultaneously at the septo‐ethmoid junction and nasofrontal suture during mastication. A third location in the anterior part of the cartilage was added during masseter stimulation and manipulation. Contraction of jaw closing muscles during mastication was accompanied by anteroposterior compressive strains (around ?1,000 με) in the septo‐ethmoid junction. Both the orientation and the magnitude of the strain suggest that the septum does not act as a vertical strut but may act in absorbing loads generated during mastication. The results from masseter stimulation and manipulation further suggest that the masticatory strain pattern arises from a combination of dorsal bending and/or shearing and anteroposterior compression of the snout. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

The use of cranial bone grafts in the closure of alveolar and anterior palatal clefts

A method is described for harvesting cancellous bone from the diploic space. In our opinion, this is the material of choice for bone grafting alveolar clefts in the 7- to 11-year age group. The procedure could be performed at an earlier age if the maxillary segments are under orthopedic control and in proper alignment. Success of the procedure depends on proper orthodontic preparation of the maxillary segments and careful, complete closure of the soft tissues across the anterior palatal cleft, the nasal lining defect, and the anterior alveolus. Results have been encouraging in terms of bone formation, and tooth migration into the bone graft can be expected if there has been no damage to the dental sac. Closure of the alveolar defect at the time of the primary lip closure would preclude the eventual need for a bone graft, but it cannot be accomplished without early, precise alignment of the maxillary segments if extensive periosteal denudation is to be avoided. The age beyond which periosteal closure alone will be inadequate to provide sufficient bone formation and should be supplemented by a bone graft remains to be established.     

Migration of radio-opaque markers injected into tendon grafts: a study using roentgen stereophotogrammetric analysis (RSA)

An increase in anterior laxity following reconstruction of the anterior cruciate ligament (ACL) can result from lengthening of the graft construct either at the sites of fixation and/or between the sites of fixation (i.e., graft substance). Roentgen stereophotogrammetric analysis (RSA), which requires that radio-opaque markers be attached to the graft, has been shown to be a useful technique in determining lengthening in these regions. Previous methods have been used for attaching radio-opaque markers to the graft, but they all have limitations particularly for single-loop grafts. Therefore, the objective of this study was to evaluate injecting markers directly into the substance of a tendon as a viable method for measuring lengthening of single-loop graft constructs by determining the maximum amount of migration after cyclic loading. Tantalum spheres of 0.8 mm diameter were used as tendon markers. Ten single-loop tendon grafts were passed through tibial tunnels drilled in calf tibias and fixed with a tibial fixation device. Two tendon markers were inserted in one tendon bundle of each graft and the grafts were cyclically loaded for 225,000 cycles from 20 N to 170 N. At specified intervals, simultaneous radiographs were obtained of the tendon markers. Marker migration was computed as the change in distance between the two tendon markers parallel to the axis of the tibial tunnel. Marker migration had a root mean square (RMS) value of less than 0.1 mm. Because the RMS value indicates the error introduced into measurements of lengthening and because this error is negligible, the method described for attaching markers to single-loop ACL grafts has the potential to be useful for determining lengthening of single-loop ACL graft constructs in in vivo studies in humans.     

Potential transformation of the anterior corneal epithelium of the common frog]

The possibility of transformation of the corneal anterior epithelium in the lens following its separation from the stroma was studied. The corneal epithelium was implanted into: a) empty eye orbit and b) cavity of lensless eye of the Rana temporaria tadpoles. In the eye orbit it continued, as in the normal development, to form the basal membrane. Although in the eye cavity the structures similar to lentoids arose but the specific lens proteins were shown to be asbent from them using immunofluorescence. In both the cases, thus, no transformation of the corneal epithelium in the lens was observed. The role of stroma in the stabilization of differentiation of the corneal anterior epithelium is discussed. It is suggested that the absence of increase in the mitotic activity is one of the causes of failure of the corneal epithelium transformation in the lens.     

The development of the connective tissue in the human orbit.

The development of the mesenchymal structures of the human orbit was studied using 10 mu or 60 mu serial sections of orbits of foetuses of 35 to 320 mm stages (C.R. length; 2-9 months). The ontogenesis of the orbital walls, the eye muscles, the blood vessels and the connective tissue was compared. This comparison revealed that the eye muscles and their fasciae together with the adventitial layers of the larger blood vessels and nerves develop first, closely linked in time to the progress of ossification and growth of most of the orbital bones. Only the (endochondral) ossification of the ethmoid starts much later. The orbital connective tissue septa development commences later, i.e. from the third month onwards, concurrently with the development of special mesenchymal condensations, a particular capillary system and adipose tissue. About five months later the adult configuration is attained.     

Ossification of the human fetal basicranium

Previous investigations of prenatal development of the human cranium have not identified the sequence of its ossification. The purpose of the present study was to elucidate the pattern of skeletal maturity of the cranial bones in the midsagittal region anterior to the foramen magnum. This study is based upon a radiographic and histochemical investigation of midsagittal tissue blocks of the cranial bases of 73 human fetuses derived from the first half of the prenatal period. A marked regularity in the ossification pattern of the bones in the midsagittal part of the human cranium was observed. Ossification starts in the frontal bone. The sequence in which the next bones ossify is occipital bone, basisphenoid bone, presphenoid bone, and ethmoid bone. The material was divided into 7 maturity stages devised for this analysis. The stages were related to general fetal size (crown-rump length) and to general fetal maturation (composite number of ossified bones in hand and foot). Skeletal development of the median part of the human cranium is not strictly correlated with the size or the stage of general maturation of the fetuses. Knowledge of normal skeletal development is necessary for understanding anomalies of development.     

Measurement of the flow in coronary artery bypass grafts

The aim of our study was to measure the flow in coronary artery bypass grafts and to compare the flow between two groups of patients. In group A the arterial revascularization was performed with both internal thoracic arteries using as a Y graft and in group B conventional revascularization using left internal thoracic artery (ITA) attached to the left anterior descending artery (LAD) and venous grafts to the other branches of the left coronary artery was performed. The flow in all grafts was measured at six time points during the operation. The cumulative flow at the end of the operation in the group A (arterial Y graft) was 51.8 +/- 24.5 ml/min and in group B (conventional technique) it was 96.8 +/- 41.1 ml/min (p < 0.05). The flow in left ITA to LAD was similar in both groups (27.3 +/- 15.9 ml/min and 26.3 +/- 16.1 ml/min in group A and B). The flow in right ITA (25.2 +/- 18.4 ml/min) was significantly lower than in venous grafts (72.5 +/- 45.5 ml/min). The calculated flow reserve was 2.2 in group A and 2.1 in group B. We found that the cumulative flow in arterial Y graft was lower in comparison with conventional revascularization. This is due to the lower flow in the right ITA branch of the Y graft compared to venous grafts. However based on clinical results, we can postulate that the flow in the Y graft is sufficient to meet the demand of the myocardium originally supplied by the left coronary artery.     

A test of positional properties of avian wing-bud mesoderm

Supernumerary wing structures are readily produced by grafting pieces of wing-bud mesoderm into different locations of host wing buds, but the mechanism underlying their formation remains obscure. The major aim of this study was to examine the ability of posterior quail wing-bud mesoderm, cultured in vitro long enough to lose ZPA (zone of polarizing activity) activity, to stimulate or participate in the formation of supernumerary structures when grafted into anterior slits of host chick wing buds. Small pieces of anterior and posterior quail wing-bud mesoderm (HH stages 21-23) were placed in in vitro culture for up to 3 days. After 2 days, ZPA activity of cultured mesoderm was lost. After the grafting of 2- to 3-day cultured anterior quail wing-bud mesoderm into posterior slits of host chick wing-buds, a consistently high percentage (70%-90%) of grafts result in formation of supernumerary cartilage; in this experiment, however, only a low percentage of grafts resulted in supernumerary cartilage when 2- to 3-day cultured posterior mesoderm was grafted into anterior slits. Taken with controls, these results show that positional differences exist between cultured anterior and posterior wing-bud mesoderm. Serial-section analysis of numerous operated wings has shown several patterns of contribution to supernumerary structures by cells of graft and host. Single supernumerary digits induced by grafts of ZPA mesoderm into anterior slits were normally composed entirely of host cells, but graft cells regularly contributed to skeletal elements of more complex supernumerary structures. Cartilage rods produced by anterior-to-posterior grafts were composed mostly of graft cells, but cartilage nodules and the bases of some rods were often mosaics of chick and quail cells. The results support the proposition that mesodermal cells of the quail wing-bud possess a form of anteroposterior positional memory, but its nature and the means by which the memory of grafted cells interacts with host mesoderm are still not clear.