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Study Objective: Part 1: To describe cases of emphysema (subcutaneous and/or mediastinal) and pneumothorax after percutaneous dilational tracheostomy (PDT) in a series of 326 patients, and to review the existing literature describing the incidence and possible mechanisms. Part 2: To analyze the potential mechanisms for the development of emphysema and pneumothorax in human cadaver models.Design: A retrospective analysis of PDTs, in combination with an anatomic study in human cadavers.Materials and Methods: Part 1: All ICU patients who underwent PDT between 1997 and 2002 were enrolled in the study. We analyzed the cases of emphysema and pneumothorax. Similar cases were retrieved from the literature and underwent a systematic review. Part 2: The relevant anatomic structures were studied. We simulated the clinical situation after PDT in a human pathologic study in order to induce subcutaneous emphysema and pneumothorax.Measurements and Results: Part 1: Five cases of subcutaneous emphysema (1.5%) and two cases of pneumothorax (0.6%) are described. In the literature search, we found 41 cases of emphysema (1.4%) and 25 cases of pneumothorax (0.8%) in a total of 3,012 patients. Part 2: Subcutaneous emphysema could easily be induced in a human cadaver model by inflating air in the pretracheal tissues and after posterior tracheal wall laceration. Air leakage was also possible through a fenestrated cannula via the space between the inner nonfenestrated cannula and outer cannula and then through the fenestration.Conclusions: We conclude that one mechanism for the development of emphysema is an imperfect positioning of the fenestrated cannula, whereby the fenestration is extraluminal. For this reason, fenestrated cannulas should not be used immediately after placement of a PDT. Posterior tracheal wall laceration is another mechanism responsible for emphysema after PDT. After perforation of the posterior tracheal wall, the pleural space can be reached easily. This may result in a pneumothorax. [ABSTRACT FROM AUTHOR]

Over the years, various vascular injection products have been developed to facilitate anatomical dissections. This study aimed to compare the most commonly used vascular injection products in fresh-frozen and formalin-embalmed cadaver specimens. An overview of the properties, advantages and limitations of each substance was given, and a comparison of vascular infusion procedures in both preservation methods was made. A literature search was performed in order to identify the most commonly used vascular injection products. Acrylic paint, latex, gelatin, silicone, Araldite F and Batson's No. 17 were selected for the study. One fresh-frozen and one embalmed cadaver forearm were infused with each injection product according to a uniform protocol. The curing time, skin- and subcutaneous tissue penetration, degree of filling of the arterial tree, extravasations, consistency of the injected vessels during dissection, and the costs of each injection fluid were noted. There was a large variation between the injection fluids in processing- and curing time, colour intensity, flexibility, fragility, elasticity, strength, toxicity and costs. All fluids were suitable for infusion. The penetration of injection fluid into the skin and subcutaneous tissue was significantly better in fresh-frozen specimens (P = 0.002 and P = 0.009, respectively), with significantly smaller branches casted (P = 0.004). Vascular infusion of fresh-frozen cadaver specimens results in a significantly better filled coloured arterial tree, enabling more detail to be achieved and smaller branches casted. The biomechanical properties of fresh-frozen soft tissues are less affected compared with formalin fixation. All the injection fluids studied are suitable for vascular infusion, but their different properties ensure that certain products and procedures are more suitable for specific study purposes., (© 2016 Anatomical Society.)

Background: Misconceptions are ideas that are inconsistent with current scientific views. They are difficult to detect and refractory to change. Misconceptions can negatively influence how new concepts in science are learned, but are rarely measured in biomedical courses. Early identification of misconceptions is of critical relevance for effective teaching, but presents a difficult task for teachers as they tend to either over- or underestimate students' prior knowledge. A systematic appreciation of the existing misconceptions is desirable. This explorative study was performed to determine whether written questions generated by students can be used to uncover their misconceptions., Methods: During a small-group work (SGW) session on Tumour Pathology in a (bio)medical bachelor course on General Pathology, students were asked to write down a question about the topic. This concerned a deepening question on disease mechanisms and not mere factual knowledge. Three independent expert pathologists determined whether the content of the questions was compatible with a misconception. Consensus was reached in all cases. Study outcomes were to determine whether misconceptions can be identified in students' written questions, and if so, to measure the frequency of misconceptions that can be encountered, and finally, to determine if the presence of such misconceptions is negatively associated with the students' course formal examination score. A subgroup analysis was performed according to gender and discipline., Results: A total of 242 students participated in the SGW sessions, of whom 221 (91 %) formulated a question. Thirty-six questions did not meet the inclusion criteria. Of the 185 questions rated, 11 % (n = 20) was compatible with a misconception. Misconceptions were only found in medical students' questions, not in biomedical science students' questions. Formal examination score on Tumour Pathology was 5.0 (SD 2.0) in the group with misconceptions and 6.7 (SD 2.4) in the group without misconceptions (p = 0.003)., Conclusions: This study demonstrates that misconceptions can be uncovered in students' written questions. The occurrence of these misconceptions was negatively associated with the formal examination score. Identification of misconceptions creates an opportunity to repair them during the remaining course sessions, in advance of the formal examination.

Medical students have to process a large amount of information during the first years of their study, which has to be retained over long periods of nonuse. Therefore, it would be beneficial when knowledge is gained in a way that promotes long-term retention. Paper-and-pencil drawings for the uptake of form-function relationships of basic tissues has been a teaching tool for a long time, but now seems to be redundant with virtual microscopy on computer-screens and printers everywhere. Several studies claimed that, apart from learning from pictures, actual drawing of images significantly improved knowledge retention. However, these studies applied only immediate post-tests. We investigated the effects of actual drawing of histological images, using randomized cross-over design and different retention periods. The first part of the study concerned esophageal and tracheal epithelium, with 384 medical and biomedical sciences students randomly assigned to either the drawing or the nondrawing group. For the second part of the study, concerning heart muscle cells, students from the previous drawing group were now assigned to the nondrawing group and vice versa. One, four, and six weeks after the experimental intervention, the students were given a free recall test and a questionnaire or drawing exercise, to determine the amount of knowledge retention. The data from this study showed that knowledge retention was significantly improved in the drawing groups compared with the nondrawing groups, even after four or six weeks. This suggests that actual drawing of histological images can be used as a tool to improve long-term knowledge retention., (© 2015 American Association of Anatomists.)

Because of a decrease of the time available for anatomy education, decisions need to be made to reduce the relevant content of the anatomy curriculum. Several expert consensus initiatives resulted in lists of structures, lacking analysis of anatomical competence. This study aims to explore the use of anatomical knowledge by medical doctors in an attempt to delineate the nature of anatomical competence. The research question is: what kind of anatomical knowledge do junior medical doctors use during a consultation with a patient presenting with a shoulder complaint? Ten junior medical doctors participated in this stimulated recall study. Each of them was videotaped while performing a consultation with a standardized patient with a complex shoulder complaint. The recording was viewed immediately after. Participants were videotaped again while verbalizing the thoughts they remembered having during the consultation. Verbatim transcriptions were coded by two coders using the qualitative data analysis ATLAS.ti software. Results were that these junior medical doctors used anatomical knowledge in all phases of the consultation, especially during physical examination. The use of anatomical terms was strongly associated with clinical reasoning and it was apparent that every subject visualized relevant anatomical information. Conclusion is that young medical doctors actively use their anatomical knowledge and it seems that the relevant anatomy consists largely of adequate visual representations in memory. Anatomy teachers should focus the students' learning activity on building an adequate visual representation of anatomical structures. This should be supported by assessments that test the quality of the students' visual representations., (© 2015 American Association of Anatomists.)

Background: It is generally assumed that learning in context increases performance. This study investigates the relationship between the characteristics of a paper-patient context (relevance and familiarity), the mechanisms through which the cognitive dimension of context could improve learning (activation of prior knowledge, elaboration and increasing retrieval cues), and test performance., Methods: A total of 145 medical students completed a pretest of 40 questions, of which half were with a patient vignette. One week later, they studied musculoskeletal anatomy in the dissection room without a paper-patient context (control group) or with (ir)relevant-(un)familiar context (experimental groups), and completed a cognitive load scale. Following a short delay, the students completed a posttest., Results: Surprisingly, our results show that students who studied in context did not perform better than students who studied without context. This finding may be explained by an interaction of the participants' expertise level, the nature of anatomical knowledge and students' approaches to learning. A relevant-familiar context only reduced the negative effect of learning the content in context. Our results suggest discouraging the introduction of an uncommon disease to illustrate a basic science concept. Higher self-perceived learning scores predict higher performance. Interestingly, students performed significantly better on the questions with context in both tests, possibly due to a 'framing effect'., Conclusions: Since studies focusing on the physical and affective dimensions of context have also failed to find a positive influence of learning in a clinically relevant context, further research seems necessary to refine our theories around the role of context in learning.

Background: Underutilization of dialogue among students during small-group work is a threat to active meaningful learning. To encourage small-group learning, we challenged students to generate written questions during a small-group work session. As gender differences have been shown to affect learning, these were also inventoried., Methods: Prospective randomized study during a bachelor General Pathology course including 459 (bio) medical students, 315 females and 144 males. The intervention was to individually generate an extra written question on disease mechanisms, followed by a selection, by each student group, of the two questions considered to be most relevant. These selected questions were open for discussion during the subsequent interactive lecture. Outcome measure was the score on tumour pathology (range 1-10) on the course examination; the effect of gender was assessed., Results: The mean score per student was 7.2 (intervention) and 6.9 (control; p = 0.22). Male students in the intervention group scored 0.5 point higher than controls (p = 0.05). In female students, this was only 0.1 point higher (p = 0.75)., Conclusions: Formulating and prioritizing an extra written question during small-group work seems to exert a positive learning effect on male students. This is an interesting approach to improve learning in male students, as they generally tend to perform less well than their female colleagues.

Despite increasing use of lateral lower leg perforator flaps, comprehensive anatomical data are still lacking. The aim of this article was to comprehensively document the pattern of usable lateral lower leg perforators. Systematic mapping of 16 cadaver leg perforators in a well-defined area was performed to elucidate location, course, length, diameter, and origin. Overall, 197 perforators were found in 16 lateral lower legs. The mean number of perforators per leg with a diameter ≥ 0.3 mm was 13.4 ± 3.6. Most perforators were found in the distal third (39.0%), followed by the middle third (32.0%), and proximal third (29.0%). A musculocutaneous course was found in 26.9% of the perforators, whereas 73.1% revealed a septocutaneous course. Most septocutaneous perforators (50.0%) were found in the distal third and most musculocutaneous perforators (58.5%) in the proximal third (P < 0.001). The majority of perforators originated from the anterior tibial artery (53.0%), followed by the peroneal artery (41.6%), and the popliteal artery (5.1%). Popliteal artery perforators (1.64 mm) were significantly larger than anterior tibial artery (0.91 mm) and peroneal artery perforators (1.02 mm; P < 0.001). These results may facilitate tissue transfer around the lateral lower leg., (© 2014 Wiley Periodicals, Inc.)

Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments, the learning effects of clay modeling were compared to either live observations (Experiment I) or video observations (Experiment II) of the clay-modeling exercise. The effects of learning were measured with multiple choice questions, extended matching questions, and recognition of structures on illustrations of cross-sections. Analysis of covariance with pretest scores as the covariate was used to elaborate the results. Experiment I showed a significantly higher post-test score for the observers, whereas Experiment II showed a significantly higher post-test score for the clay modelers. This study shows that (1) students who perform clay-modeling exercises show less gain in anatomical knowledge than students who attentively observe the same exercise being carried out and (2) performing a clay-modeling exercise is better in anatomical knowledge gain compared to the study of a video of the recorded exercise. The most important learning effect seems to be the engagement in the exercise, focusing attention and stimulating time on task., (© 2014 American Association of Anatomists.)

Assessment is an important aspect of medical education because it tests students' competence and motivates them to study. Various assessment methods, with and without images, are used in the study of anatomy. In this study, we investigated the use of extended matching questions (EMQs). To gain insight into the influence of images on the validity of test items, we focused on students' cognitive processes while they answered questions with and without images. Seventeen first-year medical students answered EMQs about gross anatomy, combined with either labeled images or answer lists, while thinking aloud. The participants' verbal reports were transcribed verbatim and then coded. Initial codes were based on a task analysis and were adapted into final codes during the coding process. Results showed that students used more cues from EMQs with images and visualized more often in EMQs with answer lists. Ready knowledge and verbal reasoning were used equally often in both conditions. In conclusion, EMQs with and without images elicit different results in this think aloud experiment, indicating different cognitive processes. They seem to measure different skills, making them valid for different testing purposes. The take-home message for anatomy teachers is that questions without images seem to test the quality of students' mental images while questions with images test their ability to interpret visual information. It makes sense to use both response formats in tests. Using images from clinical practice instead of anatomical drawings will help to improve test validity., (Copyright © 2013 American Association of Anatomists.)

In recent years, there has been a growing interest in white matter anatomy of the human brain. With advances in brain imaging techniques, the significance of white matter integrity for brain function has been demonstrated in various neurological and psychiatric disorders. As the demand for interpretation of clinical and imaging data on white matter increases, the needs for white matter anatomy education are changing. Because cross-sectional images and formalin-fixed brain specimens are often insufficient in visualizing the complexity of three-dimensional (3D) white matter anatomy, obtaining a comprehensible conception of fiber tract morphology can be difficult. Fiber dissection is a technique that allows isolation of whole fiber pathways, revealing 3D structural and functional relationships of white matter in the human brain. In this study, we describe the use of fiber dissection in combination with plastination to obtain durable and easy to use 3D white matter specimens that do not require special care or conditions. The specimens can be used as a tool in teaching white matter anatomy and structural connectivity. We included four human brains and show a series of white matter specimens of both cerebrum and cerebellum focusing on the cerebellar nuclei and associated white matter tracts, as these are especially difficult to visualize in two-dimensional specimens and demonstrate preservation of detailed human anatomy. Finally, we describe how the integration of white matter specimens with radiological information of new brain imaging techniques such as diffusion tensor imaging tractography can be used in teaching modern neuroanatomy with emphasis on structural connectivity., (© 2013 American Association of Anatomists.)

Spatial ability is an important factor in learning anatomy. Students with high scores on a mental rotation test (MRT) systematically score higher on anatomy examinations. This study aims to investigate if learning anatomy also oppositely improves the MRT-score. Five hundred first year students of medicine (n = 242, intervention) and educational sciences (n = 258, control) participated in a pretest and posttest MRT, 1 month apart. During this month, the intervention group studied anatomy and the control group studied research methods for the social sciences. In the pretest, the intervention group scored 14.40 (SD: ± 3.37) and the control group 13.17 (SD: ± 3.36) on a scale of 20, which is a significant difference (t-test, t = 4.07, df = 498, P < 0.001). Both groups show an improvement on the posttest compared to the pretest (paired samples t-test, t = 12.21/14.71, df = 257/241, P < 0.001). The improvement in the intervention group is significantly higher (ANCOVA, F = 16.59, df = 1;497, P < 0.001). It is concluded that (1) medical students studying anatomy show greater improvement between two consecutive MRTs than educational science students; (2) medical students have a higher spatial ability than educational sciences students; and (3) if a MRT is repeated there seems to be a test effect. It is concluded that spatial ability may be trained by studying anatomy. The overarching message for anatomy teachers is that a good spatial ability is beneficial for learning anatomy and learning anatomy may be beneficial for students' spatial ability. This reciprocal advantage implies that challenging students on spatial aspects of anatomical knowledge could have a twofold effect on their learning., (© 2013 American Association of Anatomists.)

In the last decade perforator flaps have been used increasingly for different indications. Many regions may serve as donor site. In this respect the posterior thigh region (PTR) has been neglected as a potential donor site for many years. The purpose of this study was to provide complete mapping of perforators supplying the posterior thigh region. Twelve fresh cadaver thighs were prepared injecting diluted acrylic paint into the iliac artery. Thereafter the posterior thighs were dissected from medial to lateral, distinguishing the perforators at the level of the superficial fascia. The perforators were localized and origin, source, length and diameter of the perforators were documented. Analysis occurred using ANOVA and the two proportion Z test. The distribution of musculocutaneous and septocutaneous perforators was respectively 69.1% and 30.9% (P = 0.002). The PTR was divided in thirds. Most perforators (53.2%) were found in de middle third of the PTR. The deep femoral artery (DFA) was the main origin of perforators (61.7%), followed by the superficial femoral artery (SFA) (27.7%) and the popliteal artery (PA) (10.6%). The DFA perforators were the longest with a mean length of 13.7 ± 4,69 cm, the SFA perforators were 9.79 ± 3.76 cm and the PA perforators were 8.6 ± 3.37 cm. The PTR offers a sufficient number of suitable perforators to serve as an adequate donorsite for pedicled and free flaps., (Copyright © 2013 Wiley Periodicals, Inc.)

A teaching tool that facilitates student understanding of a three-dimensional (3D) integration of dermatomes with peripheral cutaneous nerve field distributions is described. This model is inspired by the confusion in novice learners between dermatome maps and nerve field distribution maps. This confusion leads to the misconception that these two distribution maps fully overlap, and may stem from three sources: (1) the differences in dermatome maps in anatomical textbooks, (2) the limited views in the figures of dermatome maps and cutaneous nerve field maps, hampering the acquisition of a 3D picture, and (3) the lack of figures showing both maps together. To clarify this concept, the learning process can be facilitated by transforming the 2D drawings in textbooks to a 3D hands-on model and by merging the information from the separate maps. Commercially available models were covered with white cotton pantyhose, and borders between dermatomes were marked using the drawings from the students' required study material. Distribution maps of selected peripheral nerves were cut out from color transparencies. Both the model and the cut-out nerve fields were then at the students' disposal during a laboratory exercise. The students were instructed to affix the transparencies in the right place according to the textbook's figures. This model facilitates integrating the spatial relationships of the two types of nerve distributions. By highlighting the spatial relationship and aiming to provoke student enthusiasm, this model follows the advantages of other low-fidelity models., (© 2013 American Association of Anatomists.)

Anatomists often use images in assessments and examinations. This study aims to investigate the influence of different types of images on item difficulty and item discrimination in written assessments. A total of 210 of 460 students volunteered for an extra assessment in a gross anatomy course. This assessment contained 39 test items grouped in seven themes. The answer format alternated per theme and was either a labeled image or an answer list, resulting in two versions containing both images and answer lists. Subjects were randomly assigned to one version. Answer formats were compared through item scores. Both examinations had similar overall difficulty and reliability. Two cross-sectional images resulted in greater item difficulty and item discrimination, compared to an answer list. A schematic image of fetal circulation led to decreased item difficulty and item discrimination. Three images showed variable effects. These results show that effects on assessment scores are dependent on the type of image used. Results from the two cross-sectional images suggest an extra ability is being tested. Data from a scheme of fetal circulation suggest a cueing effect. Variable effects from other images indicate that a context-dependent interaction takes place with the content of questions. The conclusion is that item difficulty and item discrimination can be affected when images are used instead of answer lists; thus, the use of images as a response format has potential implications for the validity of test items., (Copyright © 2012 American Association of Anatomists.)

Anatomy students studying dissected anatomical specimens were subjected to either a loosely-guided, self-directed learning environment or a strictly-guided, preformatted gross anatomy laboratory session. The current study's guiding questions were: (1) do strictly-guided gross anatomy laboratory sessions lead to higher learning gains than loosely-guided experiences? and (2) are there differences in the recall of anatomical knowledge between students who undergo the two types of laboratory sessions after weeks and months? The design was a randomized controlled trial. The participants were 360 second-year medical students attending a gross anatomy laboratory course on the anatomy of the hand. Half of the students, the experimental group, were subjected without prior warning to station-based laboratory sessions; the other half, the control group, to loosely-guided laboratory sessions, which was the course's prevailing educational method at the time. The recall of anatomical knowledge was measured by written reproduction of 12 anatomical names at four points in time: immediately after the laboratory experience, then one week, five weeks, and eight months later. The strictly-guided group scored higher than the loosely-guided group at all time-points. Repeated ANOVA showed no interaction between the results of the two types of laboratory sessions (P = 0.121) and a significant between-subject effect (P ≤ 0.001). Therefore, levels of anatomical knowledge retrieved were significantly higher for the strictly-guided group than for the loosely-guided group at all times. It was concluded that gross anatomy laboratory sessions with strict instructions resulted in the recall of a larger amount of anatomical knowledge, even after eight months., (Copyright © 2012 American Association of Anatomists.)

Background: Collaborative group sessions in Nijmegen include 15 students who work all together on a group assignment. Sometimes, the group is split-up in three and every subgroup elaborates a part of the assignment. At the end, they peer-teach each other. It is believed that the split-up enhances participation and therefore learning gain., Aims: To establish the effect of group size and structure of the assignment on the perceived participation, the satisfaction and learning gain of collaborative group sessions., Methods: In this study, 27 groups of 15 students were equally divided into: A-group: all 15 students working on the complete assignment. B-group: subgroups of 5 students working on the complete assignment. C-group: subgroups of 5 students working on a smaller part, and peer-teaching each other at the end of the group session. All students took a pre-test, a post-test and a follow-up test and completed a questionnaire. Questionnaires were analyzed with a one-way analysis of variance (ANOVA) and post hoc by multiple comparisons. Learning gain was analyzed using a repeated measures ANOVA., Results: A group size effect is observed in favor of working in subgroups. Perceived participation of the students differs between A and B (p ≤ 0.001) and between A and C (p ≤ 0.001), but not between B and C. Also, an assignment effect is found in favor of the smaller assignment combined with peer-teaching. The students' satisfaction differs between A and C (p ≤ 0.003) and between B and C (p ≤ 0.001), but not between A and B. The C-group also shows higher test results (p ≤ 0.043)., Conclusions: The students prefer smaller groups as well as smaller assignments including peer-teaching. A possible larger learning gain of this format needs to be re-investigated.

On All Saints Day 2009 a monument for body donors was unveiled by the Department of Anatomy, at the Radboud University Nijmegen Medical Centre (RUNMC). Although body donation to medical science contributes substantially to the quality of medical education, the ceremony was only the first time that the RUNMC publicly reciprocated the anatomical gift. By means of the monument the department of Anatomy endeavors to express gratitude for the gift of body donors and raise awareness among students to value the gift and treat donor bodies with the proper respect. Furthermore, the large attendance of bereaved at the unveiling ceremony, revealed another equally important meaning of the monument, which is the significance of the monument to the donor kin. The wish of a body donor has large implications for the way bereaved can take leave of the donor; there is limited time to bade the deceased farewell, the body will not be available for a funeral, and the donor kin stay behind empty handed without even a grave or ashes. Therefore the monument can be meaningful by facilitating the bereaved with a place of commemoration. The design of the monument anticipates on these multiple meanings and symbolisms by placing an old marble dissection table in the shape of an altar and fixing a bronze sculpture of a phoenix as symbol of imperishableness.

Bone specific, CT-based finite element (FE) analyses have great potential to accurately predict the fracture risk of deteriorated bones. However, it has been shown that differences exist between FE-models of femora scanned in a water basin or scanned in situ within the human body, as caused by differences in measured bone mineral densities (BMD). In this study we hypothesized that these differences can be reduced by re-creating the patient CT-conditions by using an anatomically shaped physical model of the lower body. BMD distributions were obtained from four different femora that were scanned under three conditions: (1) in situ within the cadaver body, (2) in a water basin and (3) in the body model. The BMD of the three scanning protocols were compared at two locations: proximally, in the trabecular bone of the femoral head, and in the cortical bone of the femoral shaft. Proximally, no significant differences in BMD were found between the in situ scans and the scans in the body model, whereas the densities from the water basin scans were on average 10.8% lower than in situ. In the femoral shaft the differences between the three scanning protocols were insignificant. In conclusion, the body model better approached the in situ situation than a water basin. Future studies can use this body model to mimic patient situations and to develop protocols to improve the performance of the FE-models in actual patients.

Until now, research on flaps in the anteromedial thigh region has focused on flaps in specific regions. To elucidate the complete pattern of suitable anteromedial thigh perforators, an anatomical study was performed by dissecting nine thighs from different cadavers. The ideal perforator has maximum length and diameter and runs through a septum. According to the data found in our study, these perforators can predominantly be found in the middle third of the anteromedial thigh region. All of the three main thigh vessels supply perforators which can be used for flaps. Pertaining to length and diameter the most suitable perforators originate from the deep femoral artery, which can be found in the proximal and middle third of the anteromedial thigh. Musculocutaneous perforators are found to be longer than septocutaneous perforators. Because of their position, the proximal and distal third perforators should preferentially be used for local pedicled flaps. Defects in the pelvic area and around the knee can be closed with perforator flaps from the proximal and distal anteromedial thigh, respectively. Because of their diameter, length, and number, the middle third perforators should be the first choice for harvesting free flaps. Skin closure is easily achieved in the anteromedial thigh region even when larger flaps are used.

Free and pedicled flaps are frequently used in reconstruction of the lower two-thirds of the face. For these reconstructions, the submandibular facial vessels are extensively used as a receptor site. In this anatomic study, we investigate if the facial vessels in the nasolabial fold can be used as a receptor site as well. In 13 human cadavers, the facial artery and vein were dissected in the nasolabial fold in the same way as would be done during surgery. The ease of dissection and length, diameter, and location of the vessels were analyzed. The average length of the dissected artery was 28 mm (+/-11 standard deviations [SD]) and of the dissected vein, 19 mm (+/-6 SD). The mean diameter of the artery was 1.5 mm (+/-0.4 SD) and 2.5 mm (+/-0.8 SD) for the vein. In 85% of the sides, both vessels were suitable to use as a microsurgical receptor site. The easy access and the measured diameter of the facial vessels in the nasolabial fold make it a potential site for microsurgical anastomosis., (Copyright Thieme Medical Publishers.)

The anterior cruciate ligament (ACL) consists of an anteromedial bundle (AMB) and a posterolateral bundle (PLB). A reconstruction restoring the functional two-bundled nature should be able to approximate normal ACL function better than the most commonly used single-bundle reconstructions. Accurate tunnel positioning is important, but difficult. The purpose of this study was to provide a geometric description of the centre of the attachments relative to arthroscopically visible landmarks. The AMB and PLB attachment sites in 35 dissected cadaver knees were measured with a 3D system, as were anatomical landmarks of femur and tibia. At the femur, the mean ACL centre is positioned 7.9 +/- 1.4 mm (mean +/- 1 SD) shallow, along the notch roof, from the most lateral over-the-top position at the posterior edge of the intercondylar notch and from that point 4.0 +/- 1.3 mm from the notch roof, low on the surface of the lateral condyle wall. The mean AMB centre is at 7.2 +/- 1.8 and 1.4 +/- 1.7 mm, and the mean PLB centre at 8.8 +/- 1.6 and 6.7 +/- 2.0 mm. At the tibia, the mean ACL centre is positioned 5.1 +/- 1.7 mm lateral of the medial tibial spine and from that point 9.8 +/- 2.1 mm anterior. The mean AMB centre is at 3.0 +/- 1.6 and 9.4 +/- 2.2 mm, and the mean PLB centre at 7.2 +/- 1.8 and 10.1 +/- 2.1 mm. The ACL attachment geometry is well defined relative to arthroscopically visible landmarks with respect to the AMB and PLB. With simple guidelines for the surgeon, the attachments centres can be found during arthroscopic single-bundle or double-bundle reconstructions.

Objective: To measure energy cost and gait analysis in persons with stroke with and without a newly developed orthosis., Design: Immediate and long-term (3wk) intervention (before-after trial)., Setting: University medical center., Participants: Volunteer sample of 27 persons with long-term (range, 0.6-19y) hemiparetic stroke., Intervention: Three-week familiarization to the new walking aid., Main Outcome Measures: Energy cost (per distance walked), preferred walking speed (PWS), and step length. Energy cost was examined in all subjects while walking on a treadmill at 3 different velocities (PWS, PWS+30%, PWS-30%) during 3 different situations (without orthosis, with orthosis, after 3-wk orthosis familiarization). Spatiotemporal aspects of the gait pattern were examined using a 6-m instrumented walkway system., Results: Using the orthosis immediately decreased energy cost in persons with stroke during walking at the PWS (P<.001) and significantly increased walking speed (P<.005) and step length (P<.001). After 3 weeks of familiarization to the orthosis, energy cost at the PWS and at PWS+30% showed further improvement in energy cost (P<.05)., Conclusions: The newly developed orthosis immediately decreases energy cost and improves walking speed and step length in persons with long-term stroke. After only 3 weeks of orthosis familiarization, energy cost shows additional improvement.

A kinematic analysis of the knee function is important for the evaluation of total knee arthroplasties (TKA). We used the coordination and variability of rising from a chair as functional knee parameters. Twelve knee patients were measured prior to surgery (=pre-TKA group) and one year after surgery (=post-TKA group). A group of 15 healthy, age-matched subjects was selected as control group. The WOMAC questionnaire, frequently used by orthopaedic surgeons, was administered prior to the test. The test consisted of 10 times rising from a low chair and 10 times from a high chair. Knee and hip angles and angular velocities were measured with electrogoniometers. The relative phase (=MRP) between hip and knee was a measure for the coordination of rising and the standard deviation of the relative phase of the 10 trials (=SRP) was a measure for the variability. The coordination and variability of rising of the TKA patients were compared to the control group, and the relationship with the WOMAC questionnaire was calculated. The coordination of rising from a high chair and the variability of rising from both chair heights were significantly different for the pre-TKA group compared to the control group (p<0.05). The post-TKA group showed no significant differences with the control group, which indicates a functional recovery after TKA implantation. The functional parameters correlated adequately with the subjective WOMAC questionnaire. This study showed that our method is an objective measure of functionality and it will be worthwhile to use it as an additional evaluation tool.

Study Design: Semiexperimental study., Objective: To investigate the effect of an external wrist extension force on extensor muscle activity during hand gripping in patients with lateral epicondylalgia., Background: Lateral epicondylalgia or "tennis elbow" is a common, often disabling ailment affecting millions of people. An optimal treatment strategy remains to be identified. The use of an external wrist extension force may reduce the extensor muscle activity during gripping in these patients., Methods: Muscle activity of the extensor carpi radialis brevis (ECRB), extensor digitorum communis (EDC), and extensor carpi radialis longus (ECRL) was measured using surface EMG. Subjects gripped at an intensity of 10%, 20%, and 30% of the maximum voluntary contraction (MVC) force with and without the dynamic extensor brace and with and without an applied external wrist extension force of 1%, 2%, and 3% of MVC., Results: At all levels of MVC gripping, the EMG signal of the ECRB and EDC were significantly lower for gripping with than without brace. An extension force of 3% of the MVC force significantly reduced the EMG signal of all muscles in almost all measurement conditions., Conclusions: The results of this study indicate that the dynamic extensor brace as well as the external extension force significantly reduced the EMG signal of the wrist extensor muscles during gripping in patients with lateral epicondylalgia. Based on these results, the dynamic extensor brace could be a promising new intervention for lateral epicondylalgia.

Unlabelled: Lateral epicondylitis (tennis elbow) is a common, often disabling ailment. Based on the failure of current therapies, a new dynamic extensor brace has been developed. In this study, the effects of application of this brace for 3 months on the most important and disabling symptoms of patients with lateral epicondylitis were assessed. After prestratification for the duration of complaints (ie, < or = 3 months and > or = 3 months), 63 patients initially were assigned randomly to 12 weeks of brace treatment (Group 1; n = 30) or no brace treatment (Group 2; n = 33). Outcome measures included pain (VAS), pain-free grip strength, maximum grip strength, and functionality of the arm. All outcomes were assessed at 6, 12, 18, and 24 weeks. Brace treatment resulted in significant pain reduction, improved functionality of the arm, and improvement in pain-free grip strength. The beneficial effects of the dynamic extensor brace observed after 12 weeks were significantly different from the treatment group that received no brace. The beneficial effects were sustained for another 12 weeks. No correlation between duration of symptoms and treatment effects of the brace was revealed. The dynamic extensor brace is an effective therapeutic tool for treating lateral epicondylitis., Level of Evidence: Therapeutic study. Level I (randomized controlled trial with statistically significant difference). See the Guidelines for Authors for a complete description of levels of evidence.

We have quantitatively documented the insertion geometry of the main stabilising structures of the posterolateral corner of the knee in 34 human cadavers. The lateral collateral ligament inserted posterior (4.6 mm, sd 2) and proximal (1.3 mm, sd 3.6) to the lateral epicondyle of the femur and posterior (8.1 mm, sd 3.2) to the anterior point of the head of the fibula. On the femur, the popliteus tendon inserted distally (11 mm, sd 0.8) and either anterior or posterior (mean 0.84 mm anterior, sd 4) to the lateral collateral ligament. The popliteofibular ligament inserted distal (1.3 mm, sd 1.2) and anterior (0.5 mm, sd 2.0) to the tip of the styloid process of the fibula. The ligaments had a consistent pattern of insertion and, despite the variation between specimens, the standard deviations were less than the typical size of drill hole used in reconstruction of the posterolateral corner. The data provided in this study can be used in the anatomical repair and reconstruction of this region of the knee.

Objective: To gain insight in gait and calf muscle endurance in patients with severe chronic venous insufficiency., Methods: Fifteen patients with severe chronic venous insufficiency (healed or active ulcers) and 19 healthy controls were selected for this study. Subjects had to perform eight trials at preferred walking speed and eight trials at instructed walking speed (1.25 m/s) during which the gait parameters were recorded. The calf muscle endurance was tested by use of the heel-rise test., Results: Patients had a significantly lower preferred walking speed (1.25 m/s +/- 0.31) compared with healthy controls (1.44 m/s +/- 0.0.15) (p = 0.039). During preferred walking speed patients had a wider base of support (p = 0.003), a bigger step time (p = 0.005), and a bigger stride time (p = 0.004) compared with healthy controls. At instructed walking speed only base of support was different between the two groups (p = 0.016). Patients had a significantly (p = 0.003) smaller number of heel rises (14.6 +/- 7.34), indicating decreased calf muscle endurance compared with controls (23.5 +/- 6.54)., Conclusion: This study indicates a disturbed gait and decreased calf muscle endurance in patients with severe chronic venous insufficiency. The results of this study point to a possible role for gait and strength training in the rehabilitation process of patients with severe chronic venous insufficiency.

Background: In clinical practice, visual gait observation is often used to determine gait disorders and to evaluate treatment. Several reliability studies on observational gait analysis have been described in the literature and generally showed moderate reliability. However, patients with orthopedic disorders have received little attention. The objective of this study is to determine the reliability levels of visual observation of gait in patients with orthopedic disorders., Methods: The gait of thirty patients referred to a physical therapist for gait treatment was videotaped. Ten raters, 4 experienced, 4 inexperienced and 2 experts, individually evaluated these videotaped gait patterns of the patients twice, by using a structured gait analysis form. Reliability levels were established by calculating the Intraclass Correlation Coefficient (ICC), using a two-way random design and based on absolute agreement., Results: The inter-rater reliability among experienced raters (ICC = 0.42; 95%CI: 0.38-0.46) was comparable to that of the inexperienced raters (ICC = 0.40; 95%CI: 0.36-0.44). The expert raters reached a higher inter-rater reliability level (ICC = 0.54; 95%CI: 0.48-0.60). The average intra-rater reliability of the experienced raters was 0.63 (ICCs ranging from 0.57 to 0.70). The inexperienced raters reached an average intra-rater reliability of 0.57 (ICCs ranging from 0.52 to 0.62). The two expert raters attained ICC values of 0.70 and 0.74 respectively., Conclusion: Structured visual gait observation by use of a gait analysis form as described in this study was found to be moderately reliable. Clinical experience appears to increase the reliability of visual gait analysis.

Study Design: Experimental repeated-measures study., Objective: To investigate the effect of different extension forces applied to the palm of the hand on electromyographic (EMG) activity of the wrist extensor muscles during hand gripping., Background: Lateral epicondylitis is usually caused by repetitive wrist extension that leads to an overuse injury. The current theory is that the process of lateral epicondylitis begins with an overuse injury that leads to microtearing of the extensor carpi radialis brevis muscle and occasionally the extensor digitorum communis muscle. Use of an external wrist extension force might reduce muscle activity during gripping., Methods: Muscle activity was measured using surface EMG while subjects gripped at an intensity of 10%, 20%, and 30% of the maximum voluntary contraction force without, and with, an applied external wrist extension force of 1%, 2%, and 3% of maximum voluntary contraction., Results: Applying an extension force to the palm of the hand reduced EMG activity of the extensor muscles at the same strength generation during hand gripping. The muscles with the most significant reduction in EMG level, the extensor carpi radialis brevis and extensor digitorum communis, are those muscles that are most often involved with lateral epicondylitis., Conclusions: This study shows that an external extension force reduces EMG activity of the wrist extensor muscles during gripping in healthy volunteers. As the extension force increased, a greater reduction in muscle activity was noted.

The knee joints of mice can serve as a model for studying knee ligament properties. The goal of our study was to measure the structural stiffness of the medial collateral ligament (MCL) of the murine knee. A tensile test was developed for this purpose. First 84 femur-MCL-tibia complexes of 11-week-old C57Black6 mice were tested. Of four groups (n = 14 per group) the right MCL was ruptured. The mice were sacrificed at 1.5, 3, 6, and 9 weeks after the operation. The other two groups served as controls at 0 and 9 weeks after the operation. Absolute values of the structural stiffness of the healed MCLs at 1.5 weeks were initially significantly lower than their unoperated controls, but were not different from normal values at three, six, and nine weeks of healing. The structural stiffness of the unoperated controls increased by 11% at 20 weeks compared to 11 weeks of age.

Objectives: To investigate whether the intralimb coordination of the lower extremity during one-legged hopping in patients with anterior cruciate ligament reconstruction is different and less stable compared to control subjects., Design: Measures of coordination dynamics are applied to study the coordination and stability of movement patterns of the knee and ankle in patients and control subjects., Background: Due to several factors, such as loss of proprioceptive function and muscle weakness, the intralimb coordination of the lower extremity might be altered., Methods: Seven patients and 13 healthy control subjects were instructed to hop in place on one leg for 10 seconds at a comfortable frequency for each leg separately., Results and Conclusions: The one-legged hopping movement pattern of patients with anterior cruciate ligament reconstruction one-year post-operative is different and less stable compared to healthy subjects, and thus is still impaired., Relevance: This paper shows that patients, one year after reconstruction of the anterior cruciate ligament, have a different coordination pattern of the lower limb compared to a matched control group. Intersegmental coordination and stability, features that are often observed by eye during a rehabilitation process, are objectified in this study.

In vertebrates, possibly also in man, the pattern of activation of muscles during locomotion can be generated by the spinal cord (locomotor CPG, central pattern generator). However, sensory feedback is crucial to adapt the functioning of the CPG to the external requirements during gait. It is postulated that afferent input from skin and muscles can contribute to the EMG activation patterns as observed in various limb muscles during gait. The activity of the hamstrings at end swing may be partially due to stretch reflexes of these muscles. At end stance the hamstring activity may be assisted by reflexes from natural skin activation from the dorsum of the foot. In addition, more specific actions are also incorporated. For example, sural nerve stimulation induces an activation of biceps femoris (BF) whereas a suppression is usually obtained for semitendinosus (ST), indicating that the induced activation is aimed at exorotation of the lower leg. Similarly, the preferential activation of medial versus lateral gastrocnemius (GM versus GL) in sural nerve induced reflexes could favor such exorotation. It is concluded that the present evidence points towards a possible contribution of various reflexes to the motor output seen during gait for movements both inside and outside the sagittal plane.

During knee motion, the fiber bundles of ligaments are nonuniformly loaded in a recruitment pattern which is different for successive knee-joint positions. As a result, the restraining functions of these ligaments are variable. To analyze the relative restraint contributions of the fiber bundles in different knee-joint positions, a new method was developed. Its application was illustrated for the cruciate ligaments of one knee-joint specimen. The methods developed to estimate bundle forces comprise five steps. First, the three-dimensional motions of a knee specimen are measured for anterior-posterior forces, using Röntgen Stereophotogrammetric Analysis. Second, bone-ligament-bone tensile tests are performed to evaluate the mechanical properties of these structures in several relative orientations of the bones. Third, multiple fiber bundles are identified in each ligament, based on the main fiber orientations. Fourth, the nonlinear force-length relationship of each functional bundle, as defined by a stiffness and a recruitment parameter, is determined by combining the multidirectional tensile tests with a multiline-element ligament model. Finally, the information obtained is combined in a whole-joint computer model of the knee, to determine the internal forces in the initial kinematic experiment, using an inverse dynamics approach. The technique appeared to be extremely time consuming and technologically involved. However, it was demonstrated to be useful and effective. The preliminary results reveal that the fiber bundle restraints are extremely sensitive to the knee flexion angle and the restraining forces are highly variable within the ligaments. For both cruciate ligaments, a gradual transition was demonstrated in load transfer from the posterior bundles to the more anteriorly positioned ones during knee flexion. Furthermore, it appeared that relatively high forces were carried by only a few fiber bundles at each flexion angle. Based on these preliminary results, it is concluded that the determination of forces in multiple ligament bundles is important for the understanding of failure mechanisms of ligaments. In particular, alternate loading of different fiber bundles suggests that successful operative reconstruction of the cruciate ligaments may not be achieved simply by a one-bundle preparation.

The ligaments of the knee consist of fiber bundles with variable orientations, lengths and mechanical properties. In concept, however, these structures were too often seen as homogeneous structures, which are either stretched or slack during knee motions. In previous studies, we proposed a new structural concept of the ligaments of the knee. In this concept, the ligaments were considered as multi-bundle structures, with nonuniform mechanical properties and zero force lengths. The purpose of the present study was to verify this new concept. For this purpose, laxity characteristics of a human knee joint were compared as measured in an experiment and predicted in a model simulation study. In the experiment, the varus-valgus and anterior-posterior laxities of a knee-joint specimen containing the ligaments and the articular surfaces only, were determined. From this knee-joint, geometric and mechanical parameters were derived to supply the parameters for a three-dimensional quasi-static knee-joint model. These parameters included (i) the three-dimensional insertion points of bundles, defined in the four major knee ligaments, (ii) the mechanical properties of these ligament, as functions of their relative insertion orientations and (iii) three-dimensional representations of the articular surfaces. With this model the experiments were simulated. If knee-model predictions and experimental results agree, then the multi-bundle ligament models are validated, at least with respect to their functional role in anterior-posterior and varus-valgus loading of the joint. The model described the laxity characteristics in AP-translation and VV-rotation of the cadaveric knee-joint specimen reasonably well. Both display the same patterns of laxity changes during knee flexion. Only if a varus moment of 8 N m was applied and if the tibia was posteriorly loaded, did the model predict a slightly higher laxity than that measured experimentally. From the model-experiment comparisons it was concluded that the proposed structural representations of the ligaments and their mechanical property distributions seem to be valid for studying the anterior-posterior and varus-valgus laxity characteristics of the human knee-joint.

The carpal mechanism is studied during a sectioning of the ligament between the lunate and the scaphoid. A tear in this ligament is frequently observed in the clinic. After experimental lesions of this ligament, some authors say there is little effect while others report significant changes. We have conducted repetitions of these sectioning experiments using roentgen stereophotogrammetry to assess the kinematics of the carpal bones. We have found very little effect. We have also fused the scaphoid to the lunate to find out what happens to the carpal mechanism when the ligament between these bones is made stiffer. Fusion is carried out with K-wires and the effect upon the carpal mechanism is studied again. Our K-wiring of the scaphoid and lunate shows that the carpus starts to behave unpredictablely. The positions of the wires influence the outcome significantly. RELEVANCE--:The ligament between the scaphoid and the lunate has been assigned a main function in the carpal mechanism. It is still in debate, however, whether a lesion of this ligament by itself leads to the typical scapho-lunate dissociation pattern of the carpus. We have shown that a disruption of this ligament hardly influences the carpal mechanism. In time though, other ligaments may become overstretched so that finally the typical pattern may show up. K-wiring of the lunate and scaphoid to restore the connection between these bones results in a primarily unstable joint.

During knee-joint motions, the fiber bundles of the knee ligaments are nonuniformly loaded in a recruitment pattern, which depends on successive relative orientations of the insertion sites. These fiber bundles vary with respect to length, orientation and mechanical properties. As a result, the stiffness characteristics of the ligaments as a whole are variable during knee-joint motion. The purpose of the present study is to characterize this variable mechanical behavior. It is hypothesized that for this purpose it is essential to consider the ligaments mechanically as multi-bundle structures in which the variability in fiber bundle characteristics is accounted for, rather than as one-dimensional structures. To verify this hypothesis, bone-ligament-bone preparations of the ligaments were subjected to series of unidirectional subfailure tensile tests in which the relative insertion orientations were varied. For each individual test specimen, this series of tensile tests was simulated with a mathematical ligament model. Geometrically, this model consists of multiple line elements, of which the insertions and orientations are anatomically based. In a mathematical optimization process, the unknown stiffness and recruitment parameters of the line elements are identified by fitting the variable stiffness characteristics of the model to those of the test series. Thus, lumped parameters are obtained which describe the mechanical behavior of the ligament as a function of the relative insertion orientation. This method of identification was applied to all four knee ligaments. In all cases, a satisfactory fit between experimental results and computer simulation was obtained, although the residual errors were lower for the cruciate ligaments (1.0-2.4%) than for the collateral ligaments (3.7-8.1%). It was found that models with three or less line elements were very sensitive to geometrical parameters, whereas models with more than 7 line elements suffered from mathematical redundancy. Between 4 and 7 line elements little difference was found. It is concluded that the present ligament models can realistically simulate the variable tensile behavior of human knee ligaments. Hereby the hypothesis is verified that it is essential to consider the ligaments of the knee as multi-bundle structures in order to characterize fully their mechanical behavior.

The cruciate ligaments of the knee consist of numerous fascicles, groups of which comprise fibre bundles. The stabilising function of these ligaments is established by changes in the lengths and orientations of the fascicles. Understanding the function of knee ligaments thus requires an understanding of their 3-dimensional fascicle architecture. Hitherto, the cruciate ligaments have been considered functionally as single-dimensional 'ropes' or, at the most, as consisting of anterior and posterior parts. It is evident from the appearance of these ligamentous structures, however, that fascicles in more than 2 directions are present. This study investigated how many and which fibre bundles are minimally needed to preserve the main fascicle directions in the ligaments. An anatomical analysis of the cruciate ligaments was performed using a 3-dimensional measuring device. Three anterior and 3 posterior cruciate ligaments were isolated and their fascicles measures. Based on the courses of the fascicles, fibre bundles were defined, dissected bluntly, and their corresponding insertion sites measured. Finally, the insertion sites of the bundles were connected into straight-line representations by a computer and transformed to the anatomical position of the knee, so as to be useful for functional analyses of the ligaments. It was found that 6-10 bundles are sufficient to represent the main fascicle directions of the ligaments. Although the number of fibre bundles is not identical for all ligaments, the femur and the tibia are connected in a consistent way by these bundles. Even the ways in which the fibre bundles change their interrelationship from the femoral to the tibial insertion sites are comparable. The results serve as a detailed anatomical basis for functional analyses of the cruciate ligaments.

In order to evaluate the contribution of the knee ligaments to restrain joint motions, knowledge about their structural properties is required. Due to the variable relative insertion orientation of the ligaments during knee motion, however, different fiber bundles are recruited, each with their specific mechanical properties. Hence, the structural properties vary as a function of knee motion. For this reason, a relationship between the structural tensile properties and the relative insertion orientation is required in order to define the role of the ligaments in knee mechanics. In the present study, this relationship is determined by performing a series of tensile tests in which the relative orientations of the insertion sites of human knee bone-ligament-bone preparations were varied systematically. The experimentally obtained stiffness was significantly affected by the relative orientation of the insertion sites, but more profoundly for the anterior and posterior cruciate ligaments (ACL and PCL) as compared to the medial and lateral collateral ligaments (MCL and LCL). The average decreases in stiffness per 5 degrees tilt of the insertion sites were estimated at -11.6 +/- 3.5 N mm-1 (ACL), -20.9 +/- 2.7 N mm-1 (PCL), -2.6 +/- 0.9 N mm-1 (MCL) and -3.7 +/- 0.3 N mm-1 (LCL). For the PCL and the MCL these changes in stiffness with tilt were rather insensitive to the side of the femoral insertion site which was lifted. The ACL and the LCL, conversely, displayed significant differences in stiffness changes between the different tilt directions.(ABSTRACT TRUNCATED AT 250 WORDS)

The orientations of the radiotriquetral ligaments in the wrist joint suggest the role of counteracting torsions in the radiocarpal joint. This is tested in a series of kinematic experiments with three specimens, the joints being forced to rotate about the longitudinal axis of the third metacarpal. The reorientations of the marked insertion sites of the dorsal and palmar radiotriquetral ligaments are assessed and related to the individual carpal-bone movements. The three specimens react similarly to the imposed torsions: a hyperpronation is related to a dorsal flexion and a hypersupination to a palmar flexion. The dorsal radiotriquetral ligaments are highly addressed during hypersupination, but the palmar ligaments show no significant elongations during hyperpronations. The mechanism of wrist joint injuries due to trauma like a fall on the outstretched hand is poorly documented. The torsions occurring during these trauma are simulated in cadaver experiments. Large effects upon the dorsal ligaments are found in comparison to the palmar ligaments. This indicates that the palmar radiotriquetral ligaments protect the joint against hyperpronations. Planning of the restoration of hand function in the injured hand should include the different roles of these two ligaments., (Copyright © 1994. Published by Elsevier Ltd.)

It is generally recognized that the mechanical properties of soft connective tissues are affected by their structural components. We documented collagen density distributions in human knee ligaments to quantify differences in density within and between these ligaments. In order to explain the variations in mechanical properties within and between different knee ligaments as described in the literature, the distributions of collagen density were correlated with these biomechanical findings. Human knee ligaments were shown to be nonhomogeneous structures with regard to collagen density. The anterior bundles of all ligaments contained significantly more collagen mass per unit of volume than the posterior bundles did. The percentage differences between the anterior and posterior bundles, in relation to the posterior bundles, were about 25% for the anterior cruciate ligament (ACL) and the collateral ligaments and about 10% for the posterior cruciate ligament (PCL). Along the cruciate ligaments, the central segments had higher collagen densities than did segments adjacent to the ligament insertions (ACL 9%, PCL 24%). The collagen density in the ACL was significantly lower than that in the other ligaments. These variations within and between the ligaments correlate well with the variations in mechanical properties described in the literature; however, other structural differences have to be taken into account to fully explain the variations in mechanical properties from the structural components.

Present data on carpal kinematics and carpal ligament behaviour are limited to flexion and deviation movements of the hand. These motions do not represent all the wrist-joint motions which are important for the activities of daily living. The goal of this project was to obtain insight into carpal kinematics and carpal ligament behaviour during motions of the hand covering the full range of motion of the wrist joint. The carpals and the ligaments of four wrist-joint specimens were provided with radiopaque markers. These joints were subjected to Röntgenstereophotogrammetric experimentation in a large number of hand positions to determine carpal positions and ligament lengths. The movements of the carpal bones were described by means of finite helical axes (FHA). It was found that the movements of the carpals in the distal row closely resemble those of the hand. Conversely, the motions of the carpals of the proximal row appeared not to be directly proportional to the hand motions and exhibited clear out-of-plane movements. Furthermore, it could be shown that movements of the hand into the ulnodorsal quadrant of the full range of hand motion corresponds to larger helical rotations and translations for most of the carpals than when the hand was moved into any other quadrant. The maximal ligament length changes determined did not exceed the length changes reported for pure flexion and pure deviation movements of the hand.

A method has been developed to calculate the forces that are developed in the ligaments of a joint specimen during motions. This indirect method is needed since direct measurements fail in the case of small ligaments. As an example the small ligaments of the carpal joint are considered. The rationale of the method is that the force generated in a ligament depends on the amount of strain to which it is subjected and on its material characteristics. In the method presented the lengths of the ligaments are determined in vitro at several joint positions by means of röntgenstereophotogrammetry. The zero-force length and the force-elongation relationship are determined on the same ligaments isolated in a materials testing machine. Over a considerable part of the strain range the measurement errors are relatively small compared to the forces determined, less than 10%. The method is applicable to joints in situations where other measuring methods cannot be used. The present analysis shows, however, that the force values determined are susceptible to preconditioning of the ligaments. In preconditioned ligaments the forces could be up to 50% lower than in the non-preconditioned situation. This suggests that ligament forces may vary considerably in vivo, depending on the extent of preconditioning provoked by a particular function.

The forces induced in tiny wrist joint ligaments must be estimated in order to understand their role in the mechanism of the joint. We estimated forces in a number of selected ligaments in seven human wrist joint specimens, using a noninvasive method. The method is based on the rationale that the force generated in a ligament depends on its change of length with the joint under load. In vitro length changes of the ligaments were determined during flexion and deviation movements of the hand, using a roentgenstereophotogrammetric analysis technique. Subsequently, bone-ligament-bone (BLB) preparations were dissected from the specimens. From these BLB preparations the zero-force length and the force-elongation relationship were determined in a material testing machine. The forces generated in the ligaments during flexion and deviation were calculated by combining results on the in vitro ligament length changes, the zero-force length, and the force-elongation relationship. Large interspecimen variations of the force patterns were found. Due to this variability, it is not possible to obtain quantitative models for the kinetic behavior of the ligaments. However, qualitative trends could be distilled from the strain and force patterns. It is clear that for most ligaments, the zero-force lengths were not equal to the lengths they possessed in the neutral position of the hand. Furthermore, it could be shown which motions of the hand would most likely strain a particular ligament. It could be shown that the variations in the force patterns originate mainly from variations in the zero-force lengths, and from variations in the force-strain relationship between specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

In the present study the stiffness of the superficial ligaments of 14 human cadaver wrist joints have been determined. In these experiments the tested, fresh-frozen carpal joints are divided into a number of bone-ligament-bone complexes, which are loaded in a tensile testing machine at a rate of 66% of the ligaments' initial length per second to a maximal strain of 15%. From the force-elongation curves and ligament dimensions the tangent moduli for the ligament-bone strips are derived. The results show that, with regard to the tangent modulus, there is not a clear differentiation among ligament strips. Only the dorsal radiotriquetrum ligament (RTD) and the palmar radiocapitate ligament (RCP) appear to consist of a material of a relatively high tangent modulus, about 93 and 83 MPa, respectively. The other seven ligaments tested have similar tangent moduli, ranging from 25 to about 50 MPa.

The cross-sectional area of a particular ligament is an important characteristic in order to establish the biomechanical properties of this ligament. Calculations of the cross-sectional areas of the ligaments of the wrist joint are made from two three-dimensional models. It is discussed that differences between the presented and the scarcely published data on cross-sectional areas are the result of different divisions of the wrist-joint ligamentous complex into separate ligaments.

In five fresh human cadaver wrist joints six carpal ligaments and seven carpal bones were marked with small, radio-opaque pellets. Using a roentgenstereophotogrammetric measuring system, the ligamentous length changes and the kinematics of carpal bones were determined in different flexion and deviation positions of the hand. The data generated by this method differ significantly from lengthening data predicted by current concepts on carpal ligament functioning. The motions of carpal bones and the lengthening of the carpal ligaments were related to each other. It appeared that most carpal ligaments lengthen only during one half of a full movement cycle. Hence, ligaments seem to constrain either a dorsal- or a palmar-directed motion of the hand, or an ulnar- or a radial-directed motion of the hand. When the hand is in maximal radial deviation or maximal palmar flexion, none of the ligaments has a greater length than in the neutral situation. The tested parts of the lunatotriquetrum palmar ligament do not lengthen during any movement of the hand. Significant lengthening relative to the neutral situation was found for the radiocapitate palmar ligament (6.5% in maximal ulnar deviation and 11.7% in maximal dorsal flexion of the hand), and for the distal string of the radiolunate palmar ligament (6.4% in maximal ulnar deviation). It was confirmed that the carpals, apart from moving in the plane in which the hand motion takes place, also execute considerable out-of-plane motions during hand motions. The combination of these experimentally and simultaneously determined data on length change and on the movements of carpal bones are found to be necessary in order to give suitable explanations for the observed separate kinematical phenomena.

This paper is one of several contributions in a series, illustrating the application of a specific deductive methodology to explain diversity of form. The methodology facilitates the explanation of feeding morphologies in various ducks as a transformation of the mallard's feeding design maximized for specific proportions of performance that are contributed by pecking and filter feeding mechanisms. The earlier described anatomy and formal analyses of the three mechanisms in the mallard served as the initial conditions used in simulation models. Four elements of the feeding system were chosen that play a major role in all three mechanisms. For each element, the main parameter was selected: storage capacity of the rostral mouth cavity, transport capacity of the rostral mouth tube, storage capacity of the caudal mouth cavity and transport capacity of the caudal mouth tube. The boundary conditions for the simulation were determined from internal organismic constraints. The total food uptake of the mallard was regarded as the function to be maximized. This 'object' function is the summation of the food uptake by one second of pecking and one second of filter feeding. The drinking mechanism was shown not to interfere, since that mechanism operates sufficiently whenever the pumping mechanism works properly. The 'object' function, made up by the pecking and filter feeding performances was graphed. From these graphs a morphospace was developed: the region within which modifications of the mouth design are feasible. This procedure allowed examination of the general hypothesis that different modifications of one design for a complex multi-role system are explainable from differences in proportions of the functional performance contributed by each of the roles. Two predictions were evaluated more specifically: 1) If filter feeding performance must increase for a specific change in total food uptake, the volume of the rostral mouth cavity must increase; this requires widening and lengthening of the rostral maxillar portion and also a phase shift in jaw and lingual motion patterns, increasing the stroke volume. 2) If pecking performance must increase, the transport capacity of the rostral mouth tube must increase; this requires shortening of the maxillar mid portion. These two predictions regarding change in mouth morphology were borne out by shovelers and tufted ducks, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

The shape and size of insertion sites associated to the relevant carpal ligaments are given in terms of outlines and surface areas. The sites are reconstructed as areas on the contours of the carpal bones with the use of three-dimensional reconstruction of serially sectioned wrists. The computer-models of the wrist-joint show accurately the sofar uncharted three-dimensional orientations of the insertions. The documentation of the surface areas is a first approach to the quantitative analysis of the bone-ligament complex of the wrist-joint. This is needed in future studies about the role of the ligament behavior in wrist-joint motion.