Marjorie Johnson

A cadaveric study of the anterolateral ligament: re-introducing the lateral capsular ligament.

PurposeThe purpose of this study was to verify and characterize the anatomical properties of the anterolateral capsule, with the aim of establishing a more accurate anatomical description of the anterolateral ligament (ALL). Furthermore, microscopic analysis of the tissue was performed to determine whether the ALL can morphologically be classified as ligamentous tissue, as well as reveal any potential functional characteristics.MethodsThree different modalities were used to validate the existence of the ALL: magnetic resonance imagining (MRI), anatomical dissection, and histological analysis. Ten fresh-frozen cadaveric knee specimens underwent MRI, followed by anatomical dissection which allowed comparison of MRI to gross anatomy. Nine additional fresh-frozen cadaveric knees (19 total) were dissected for a further anatomical description. Four specimens underwent H&E staining to look at morphological characteristics, and one specimen was analysed using immunohistochemistry to locate peripheral nervous innervation.ResultsThe ALL was found in all ten knees undergoing MRI and all nineteen knees undergoing anatomical dissection, with MRI being able to predict its corresponding anatomical dissection. The ALL was found to have bone-to-bone attachment points from the lateral femoral epicondyle to the lateral tibia, in addition to a prominent meniscal attachment. Histological sectioning showed ALL morphology to be characteristic of ligamentous tissue, having dense, regularly organized collagenous bundles. Immunohistochemistry revealed a large network of peripheral nervous innervation, indicating a potential proprioceptive role.ConclusionFrom this study, the ALL is an independent structure in the anterolateral compartment of the knee and may serve a proprioceptive role in knee mechanics.

Development and Validation of a New Technique for Ultrasound-guided Stellate Ganglion Block

Background and Objectives: Although the stellate ganglion is located anteriorly to the first rib, anesthetic block is routinely performed at the C6 level. Ultrasonography allegedly improves accuracy of needle placement and spread of injectate. The technique is relatively new, and the optimal approach has not been determined. Moreover, the location of the cervical sympathetic trunk relative to the prevertebral fascia is debatable. Methods: Three-dimensional sonography was performed on 10 healthy volunteers, and image reconstruction was completed. On the basis of analysis of pertinent anatomy, a lateral trajectory for needle placement was simulated. Accuracy was tested by injection of methylene blue in cadavers. A clinical validation study was then conducted. A block needle was inserted according to the predetermined lateral path, and 5 mL of a mixture of bupivacaine and iohexol was injected. Spread of the contrast agent was verified fluoroscopically. Results: Image reconstruction revealed that the cervical sympathetic trunk is located posterolaterally to the prevertebral fascia on the surface of the longus colli muscle. The mean anteroposterior width of the muscle at the C6 level was 11 mm. The lateral approach does not interfere with any visceral or nerve structures. Anatomic dissection in cadavers confirmed entirely subfascial spread of the dye and staining of the sympathetic trunk. The contrast agent spread was seen in all patients between the C4 and T1 levels in a typical prevertebral pattern. Conclusions: This study revealed that, at the C6 level, the cervical sympathetic trunk lies entirely subfascially. Subfascial injection via the lateral approach ensures reliable spread of a solution to the stellate ganglion.

Explorable three-dimensional digital model of the female pelvis, pelvic contents, and perineum for anatomical education.

The anatomy of the pelvis is complex, multilayered, and its three‐dimensional organization is conceptually difficult for students to grasp. The aim of this project was to create an explorable and projectable stereoscopic, three‐dimensional (3D) model of the female pelvis and pelvic contents for anatomical education. The model was created using cryosection images obtained from the Visible Human Project, in conjunction with a general‐purpose three‐dimensional segmentation and surface‐rendering program. Anatomical areas of interest were identified and labeled on consecutive images. Each 2D slice was reassembled, forming a three‐dimensional model. The model includes the pelvic girdle, organs of the pelvic cavity, surrounding musculature, the perineum, neurovascular structures, and the peritoneum. Each structure can be controlled separately (e.g. added, subtracted, made transparent) to reveal organization and/or relationships between structures. The model can be manipulated and/or projected stereoscopically to visualize structures and relationships from different angles with excellent spatial perception. Because of its ease of use and versatility, we expect this model may provide a powerful teaching tool for learning in the classroom or in the laboratory. Anat Sci Educ.

Increased motor unit potential shape variability across consecutive motor unit discharges in the tibialis anterior and vastus medialis muscles of healthy older subjects

OBJECTIVE To study the potential utility of using near fiber (NF) jiggle as an assessment of neuromuscular transmission stability in healthy older subjects using decomposition-based quantitative electromyography (DQEMG). METHODS The tibialis anterior (TA) and vastus medialis (VM) muscles were tested in 9 older men (77 ± 5 years) and 9 young male control subjects (23 ± 0.3 years). Simultaneous surface and needle-detected electromyographic (EMG) signals were collected during voluntary contractions, and then analyzed using DQEMG. Motor unit potential (MUP) and NF MUP parameters were analyzed. RESULTS NF jiggle was significantly increased for both the TA and VM in the old age group relative to the younger controls (P<0.05). NF jiggle was significantly higher in the TA compared to VM (P<0.05). For TA, NF jiggle was negatively correlated with MUNE, and positively correlated with S-MUP amplitude, NF count, MUP duration, MUP peak-to-peak voltage, and MUP area (P<0.05). For VM, NF jiggle was positively correlated with NF count and MUP area (P<0.05), and no significant correlations were found between NF jiggle and S-MUP amplitude, MUP duration, or MUP peak-to-peak voltage (MUNE was not calculated for VM, so no correlation could be made). CONCLUSIONS Healthy aging is associated with neuromuscular transmission instability (increased NF jiggle) and MU remodeling, which can be measured using DQEMG. SIGNIFICANCE NF jiggle derived from DQEMG can be a useful method of identifying neuromuscular dysfunction at various stages of MU remodeling and aging.

The development and assessment of an online microscopic anatomy laboratory course.

Increasing enrollment in post‐secondary institutions across North America, along with an increase in popularity of and demand for distance education is pressuring institutions to offer a greater number and variety of courses online. A fully online laboratory course in microscopic anatomy (histology) which can be taught simultaneously with a face‐to‐face (F2F) version of the same course has been developed. This full year course was offered in the Fall/Winter (FW) terms in both F2F and online formats. To ensure that the online course was of the same quality as the F2F format, a number of performance indicators were evaluated. The same course, offered exclusively online during the summer with a compressed time frame, was also evaluated. Senior undergraduate students self‐selected which version of the course they would enroll in. Course assessment outcomes were compared while incoming grades were used as a predictor for course performance. There were no significant differences between the incoming grades for the F2F FW and Online FW courses; similarly, there were no significant differences between outcomes for these formats. There were significant differences between the incoming grades of the F2F FW and Summer Online students. However, there were no significant differences among any of the outcomes for any of the formats offered. Incoming grades were strong, significant predictors of course performance for both formats. These results indicate that an online laboratory course in microscopic anatomy is an effective format for delivering histology course content, therefore giving students greater options for course selections. Anat Sci Educ 6: 246–256.

An anatomic study of coronoid cartilage thickness with special reference to fractures.

BACKGROUND Current coronoid fracture classification systems are based on fragment size and configuration using plain radiographs and/or computed tomography (CT). During surgery, coronoid fracture fragments appear much larger than anticipated because cartilage is radiolucent and therefore not accounted for with preoperative imaging. The purpose of this imaging study was to quantify the articular cartilage thickness of the coronoid, with reference to coronoid fractures. MATERIALS AND METHODS Twenty-four cadaveric ulnae were dissected, imaged with CT, and analyzed by use of image analysis software. Thirteen identifiable landmarks were chosen on the coronoid, olecranon, and proximal radioulnar joint to measure articular cartilage thickness. Intraobserver reliability and interobserver reliability were determined. RESULTS Cartilage thickness was highest at the coronoid tip, with a mean of 3.0 mm (range, 1.7-4.6 mm). Cartilage thickness at the tip correlated inversely with age (P < .01) and correlated strongly with overall ulnar height and ulnar length (P < .05). All measurements had excellent intraobserver and interobserver reliability. CONCLUSION The thickness of cartilage on the coronoid tip is not inconsequential. The results of this study indicate that a 2-mm coronoid tip fracture on CT scan may actually appear to be a mean of 5 mm thick when viewed at the time of surgery. Clinically, this is important because it may alter the classification, the decision to treat, or the type of fixation used. Importantly, biomechanical cadaveric studies assessing coronoid injuries have incorporated cartilage thickness into coronoid size measurements when creating simulated fractures; therefore, it is critical that the conclusions of such biomechanical studies be scrutinized with regard to their clinical recommendations. Surgeons should be aware of these discrepancies.

Injectate spread following ultrasound-guided lateral to medial approach for dual transversus abdominis plane blocks.

Bilateral dual transversus abdominis plane (BD‐TAP) injections were devised to cover the T7–8 and L1 dermatomes, which are usually spared with classical and mid‐axillary TAP injections. The purpose of this study was to delineate the vertical and lateral extent of injectate spread following a lateral to medial approach for TAP injections in embalmed cadavers.

Comparison of anatomic landmarks and ultrasound guidance for intercostal nerve injections in cadavers.

Background and Objectives Intercostal nerve (ICN) injections are routinely performed under anatomic landmark or fluoroscopic guidance for acute and chronic pain indications. Ultrasound (US) is being used increasingly to perform ICN injections, but there is lack of evidence to support categorically the benefits of US over conventional techniques. We compared guidance with US versus anatomic landmarks for accuracy and safety of ICN injections in cadavers in a 2-phase study that included evaluation of deposition of injected dye by dissection and spread of contrast on fluoroscopy. Methods A cadaver experiment was performed to validate US as an imaging modality for ICN blocks. In the first phase of the study, 12 ICN injections with 2 different volumes of dye were performed in 1 cadaver using anatomic landmarks on one side and US-guidance on the other (6 injections on each side). The cadaver was then dissected to evaluate spread of the dye. The second phase of the study consisted of 74 ICN injections (37 US-guided and 37 using anatomic landmarks) of contrast dye in 6 non-embalmed cadavers followed by fluoroscopy to evaluate spread of the contrast dye. Results In the first phase of the study, the intercostal space was identified with US at all levels. Injection of 2 mL of dye was sufficient to ensure compete staining of the ICN for 5 of 6 US-guided injections but anatomic landmark guidance resulted in correct injection at only 2 of 6 intercostal spaces. No intravascular injection was found on dissection with either of the guidance techniques. In the second phase of the study, US-guidance was associated with a higher rate of intercostal spread of 1 mL of contrast dye on fluoroscopy compared with anatomic landmarks guidance (97% vs 70%; P = 0.017). Conclusions Ultrasound confers higher accuracy and allows use of lower volumes of injectate compared with anatomic landmarks as a guidance method for ICN injections in cadavers. Ultrasound may be a viable alternative to anatomic landmarks as a guidance method for ICN injections.

Defining the Efficacy of Aortic Root Enlargement Procedures: A Comparative Analysis of Surgical Techniques

BACKGROUND Aortic root enlargement (ARE) procedures are believed to allow implantation of larger valve prostheses; however, little evidence exists to support the specific efficacy of various techniques. METHODS Using a cadaveric model, 20 adult (72.4 ± 15.3 years) hearts were stratified into 4 groups based on annular diameter: <20 mm, 20-22 mm, 22-24 mm, and >24 mm. Each heart underwent an aortic valve replacement following a Nicks, Manougian, aortoventriculoplasty and modified Bentall procedure, with appropriate reversals between procedures. RESULTS All 4 groups experienced similar increases in annular diameter (P = 0.43) and prosthesis size implanted (P = 0.51) with each enlargement technique. The Nicks, Manougian, modified Bentall and aortoventriculoplasty procedures enlarged the annulus by 0.43 ± 0.45 mm, 3.63 ± 0.95 mm, 0.78 ± 0.65 mm, and 6.08 ± 1.19 mm, respectively (P < 0.001). No significant change in prosthesis size was observed after the Nicks procedure (P = not significant). Increases of 1.3 ± 0.5, 1.3 ± 0.5, and 2.7 ± 0.6 prosthesis sizes were achieved with the Manougian, modified Bentall and aortoventriculoplasty techniques respectively (P < 0.001). CONCLUSIONS ARE procedures appear equally efficacious in both small and larger aortic roots. Although all 4 ARE techniques increased the annular diameter, only the Manougian, modified Bentall and aortoventriculoplasty procedures allowed for the implantation of a larger prosthetic valve. The Nicks procedure, which is likely the most commonly performed ARE, does not allow for the implantation of a larger prosthesis. Surgeon preference and patient factors may help in selecting the most appropriate ARE technique, as the modified Bentall and Manougian procedures achieved similar increases in valve size.

Integrating Anatomy Training into Radiation Oncology Residency: Considerations for Developing a Multidisciplinary, Interactive Learning Module for Adult Learners.

Radiation oncologists require an in‐depth understanding of anatomical relationships for modern clinical practice, although most do not receive formal anatomy training during residency. To fulfill the need for instruction in relevant anatomy, a series of four multidisciplinary, interactive learning modules were developed for a cohort of radiation oncology and medical physics residents. Instructional design was based on established learning theories, with the intent of integrating knowledge of specific anatomical regions with radiology and radiation oncology practice. Each session included presentations by a radiologist and a radiation oncologist, as well as hands‐on exploration of anatomical specimens with guidance from anatomists. Pre‐ and post‐tests distributed during each session showed significant short‐term knowledge retention. According to qualitative surveys and exit interviews, participants felt more comfort’ with delineating structures, gross anatomy, and radiograph interpretation at the end of each session. Overall participant experience was positive, and the modules were considered effective for learning radiologic anatomy. Suggestions for future interventions include more time, increased clinical application, additional contouring practice and feedback, and improved coordination between each of the three disciplines. Results and conclusions from this study will be used to inform the design of a future multi‐day national workshop for Canadian radiation oncology residents. Anat Sci Educ 8: 158–165.