The fibular collateral ligament of the knee: a detailed review.

The fibular collateral ligament (FCL) is one of the larger ligaments of the knee. The FCL, along with the popliteus tendon, arcuate popliteal ligament, and joint capsule, make up the posterolateral corner of the knee. Recently, there has there been an increased awareness and research on the structures of the posterolateral corner of the knee, particularly the FCL. Studying the detailed structure of the FCL may provide a better understanding that can lead to better diagnosis and treatments following injury. Therefore, this article reviews the FCL, which appears to be the primary restraint to varus rotation but is poorly oriented to resist external rotation of the knee.

Morphometry of the fibular collateral ligament: anatomic study with comprehensive review of the literature.

There is no consensus in the literature related to the morphology, bony attachments, and variations of the fibular collateral ligament (FCL) of the knee. Our purpose was to investigate FCL morphology and to review reports in the literature regarding this structure. Seventy knees from formalin-fixed, adult cadavers were dissected and a digital caliper was used to measure FCL length, width, distance from proximal attachment to articular surface (PA→AS), and distance from distal attachment to articular surface (DA→AS). The mean (SE) length and width of all FCLs was 48.3 (1.1) mm and 4 (0.16) mm, respectively. The mean (SE) PA→AS and DA→AS of all FCLs was 22 (0.8) mm and 24.8 (1) mm, respectively. We found a direct relationship between the PA→AS and DA→AS distances (Spearman rho = 0.527, P = 0.002) and this association was independent of age and sex. Two FCL variations were found: a bifurcate ligament with two distal bands and a trifurcate ligament with three distal bands, all of which attached to the fibular head. Our literature review revealed that only 2/10 cadaveric FCL morphology studies reported variations similar to the current study. Further, there was variability in the reported location of the FCL proximal attachment. When combining our data with these studies, 105/219 FCLs directly attached to the apex of the lateral epicondyle (LE), 10/219 to a fovea posterior to the LE, and 104/219 posterior and proximal to the LE. These data may have implications related to FCL injury and repair.

Anatomic study of the suboccipital artery of Salmon with surgical significance.

The anatomy of the muscular branches of the vertebral arteries has clinical relevance during surgical procedures, suboccipital injections, and manual therapies. Each vertebral artery is divided into four segments. Segment V3, found in the suboccipital triangle, courses posteromedially around the lateral mass to lie in a groove on the posterior arch of the atlas, ultimately coursing beneath the posterior atlanto-occipital membrane to enter the skull. Although not always present, any muscular branch that emanates from this segment to supply the suboccipital muscles is called the suboccipital artery of Salmon. There is a paucity of literature on this artery despite its clinical relevancy. We found the suboccipital artery of Salmon in 10 (67%) of 15 embalmed adult cadavers. This frequency is considerably higher than that in previous reports. Two (20%) of the 10 cadavers demonstrated bilateral and symmetrical suboccipital arteries of Salmon (one artery on each side). Four (40%) of the 10 cadavers had an arrangement of two parallel suboccipital arteries of Salmon on one side, and one on the contralateral side. Three (30%) of the 10 cadavers displayed an asymmetrical unilateral arrangement (only one artery). One (10%) of the 10 cadavers displayed the unique arrangement of three arteries of Salmon on one side and one artery on the contralateral side. This study adds to a limited, but growing, body of knowledge by providing photographic evidence of the course and arrangement of these arteries and, therefore, can be of value to surgeons and other clinicians whose procedures focus on the suboccipital region.

Anatomico-radiological Study of the Bifurcate Ligament of the Foot with Clinical Significance.

Introduction Lateral ankle sprain caused by forcible plantar flexion and inversion of the foot commonly damages the anterior talofibular ligament and other ligaments. Unfortunately, involvement of the bifurcate ligament (BL) is often overlooked when assessing such injuries in clinical practice and identification of this ligament on magnetic resonance (MR) scans can be challenging. Anatomically, the BL is a Y-shaped structure with two bands: the calcaneonavicular ligament (CNL) and calcaneocuboid ligament (CCL). There are few anatomical studies on the morphometric characteristics of the BL and even fewer biomechanical studies. Therefore, the objective of this anatomico-radiological study was to investigate the morphology of the BL using a multifaceted approach, and classify the fiber characteristics of the CNL and CCL. Materials and methods We measured the length and the width of 53 embalmed cadaveric feet. Meticulous dissection of each foot was performed to expose the BL. Measurements of the length, width, thickness, and shape of the CNL and CCL were taken using a digital caliper. We also documented the fiber orientation of each ligament, and used a goniometer to measure the bifurcation angle between the CNL and CCL via two methods. Confirmatory histologic analysis of the ligaments was performed and digital radiographs of the ligaments with attached radiopaque monofilament were taken. We also included an MR scan of the BL. Using descriptive and inferential statistics, we documented any significant relationships between the variables. Results  Mean (range) age at death of cadavers was 76 (42-94) years. The CNL was found in all the feet and the CCL was not present in 9.4% of the feet. Mean (standard deviation) length of the CNL and CCL was 22.7 (4.12) mm and 10.9 (2.53) mm, respectively. Mean (standard deviation) thickness of the CNL and CCL was 3.23 (1.56) mm and 1.48 (0.71) mm, respectively. Related to ligament morphology, the CNL was most frequently cord shaped (67.92%) and the CCL was most frequently flat shaped (83.33%). The mean bifurcation angle measured 32.75o and 29.31o in methods 1 and 2, respectively. The correlation between the two measured angles was very strong (p < 0.001). Discussion We found that 90.6% of feet had both the CNL and CCL, 9.4% had the CNL and no CCL, and none (0%) had the CCL and no CNL. These frequencies are similar to a recent Japanese study. Our sample of donors were American and predominantly white. Whether the difference in frequencies between the studies is related to ethnicity is unknown and requires future investigation. Interestingly, on average the CNLs were twice as long and twice as thick as the CCLs. The CCLs tended to be wider distally and tapered compared to the CNLs. Conclusions Our findings better classify the morphology and fiber orientation of the BL. Coupled with the radiographs and MR scan, our data may be of particular value to radiologists and surgeons. Our BL fiber orientation classification system and angle measurements can pave the way for future biomechanical studies to investigate any relationships between fiber type, angle, and strength of the constituent bands. More accurate descriptions of the BL should lead to improved diagnosis and treatment of ligamentous injuries of the foot.

Morphometric analysis of temporomandibular joint elements.

PURPOSE: To study the morphology of temporomandibular joint (TMJ) elements and examine the feasibility of a novel biofidelic articular disc casting technique. METHODS: 18 formalin-fixed cadavers (77.8% female, 22.2% male) with mean (SD) death age of 71.9 (13.7) years were used for this study. In each specimen the masseter muscle, mandibular ramus, and articular disc were dissected bilaterally and measured for length, width, and thickness. All anatomic measurements were made using a digital slide caliper (Hawk Inc., Cleveland, OH). Further, a novel method for the creation of biofidelic articular disc models was established through trial and error. Models were measured for accuracy against their biological counterparts. RESULTS: Left articular disc length and thickness were inversely correlated (r = -0.58, p < 0.049). Direct correlations existed between right disc and ramus thickness (r = 0.56, p < 0.039), masseter length and thickness (r = 0.59, p < 0.009), and masseter width and thickness (r = 0.66, p < 0.003). Comparison of the model measurements with their biological counterparts found no significant differences. DISCUSSION: These observed correlations between elements of the TMJ hold relevance for oral-maxillofacial surgeons and researchers examining disorders of the TMJ. Additionally, our casting technique proved accurate in modeling human articular discs.

Anatomical Study of the Cervical and Interosseous Talocalcaneal Ligaments of the Foot with Surgical Relevance.

There is conflicting evidence regarding the morphology and orientation of the cervical ligament (CL) and interosseous talocalcaneal ligament (ITCL). The morphology of the CL and its relationship to the ITCL were studied to obtain an understanding of these structures. Twenty-six feet (13 left, 13 right) were obtained from formalin-fixed cadavers (14 females, four males) with the mean standard deviation (SD) age at death 80.9 (12.9) years. All measurements were made with a digital caliper. The length and width of the foot, the width and height of the talus, were measured. The talus was cut coronally to expose the ITCL and qualitative observations were noted. The mean (SD) heights and widths of the CL at the anterior, posterior, superior, and inferior points were 8.27 (2.52), 13.95 (5.96), 9.15 (2.45), and 11.90 (4.30) mm, respectively. The mean (SD) thicknesses of the CL at the superoanterior, superoposterior, inferoanterior, inferoposterior, and central points were 0.62 (0.24), 1.05 (0.30), 0.70 (0.26), 1.20 (0.34), and 0.97 (0.31) mm, respectively. The fibers of the CL are oriented at a slight superoanterior to inferoposterior angle, whereas the fibers of the ITCL are oriented in a slight superomedial to inferolateral angle. The fibers of the CL and ITCL overlap inside the tarsal sinus with the CL positioned anteriorly, which helps to distinguish the two ligaments. In this study, we identified the morphometrics of the CL and described the CL and ITCL qualitatively. These results are relevant to introducing innovative techniques for reconstructive surgery of the subtalar ligaments in order to repair, for example, subtalar instability.

Relationship Between the Intersesamoid Ligament and Sesamoid Bones in Cadaveric Feet with Hallux Valgus.

There is heterogeneity in the literature regarding the anatomy, exact location, and definition of the intersesamoid ligament (IL). Anatomic knowledge of the IL and its variations are important for surgeons who undertake corrective surgery for hallux abducto valgus (HAV). The IL was dissected in 16 feet from 32 formalin-fixed cadavers (12 females, four males; mean age at death, 76.6 years) to examine its morphology. The length, width, and thickness of its constituent bands were recorded with a digital caliper. Descriptive and correlational statistics were used to investigate the relationships between band size, age at death, and sex. A literature review was conducted to compare our data to those of previous studies. Results suggest that the size of the sesamoids may change as a result of HAV deforming forces, which may cause lengthening of the IL. The IL stabilizes the sesamoid apparatus of the first metatarsophalangeal joint (MPJ) and should be evaluated in HAV correction. Anatomic knowledge of the complex morphology and relations between the IL and sesamoids is critically important for surgeons correcting HAV deformities.

Anatomic study of the deltoid ligament of the ankle.

BACKGROUND: There is heterogeneity in the literature regarding the anatomy and number of ligamentous bands that form the deltoid ligament (DL). Anatomic knowledge of the DL and its variations are important for surgeons who repair ankle fractures. METHODS: The DL was dissected in 33 ankles from 17 formalin-fixed cadavers (mean age at death, 76.6 years) to examine its morphology. The length, width, and thickness of its constituent bands were recorded with a digital caliper. Descriptive and correlational statistics were used to investigate the relationships between band size, age at death, and sex. A literature review was conducted to compare our data to those of previous studies. RESULTS: The DL has superficial and deep layers with up to 8 different bands. CONCLUSION: The DL stabilizes the medial ankle and should be evaluated in flatfoot deformities and severe ankle fractures. CLINICAL RELEVANCE: Anatomic knowledge of DL variations should aid the surgeon in repairing torn DLs.

A chemical application method with underwater dissection to improve anatomic identification of cadaveric foot and ankle structures in podiatric education.

BACKGROUND: Many cadaver-based anatomy courses and surgical workshops use prosections to help podiatry students and residents learn clinically relevant anatomy. The quality of these prosections is variable and dependent upon the methods used to prepare them. These methods have not been adequately described in the literature, and few studies describe the use of chemicals to prepare prosections of the cadaveric foot and ankle. Recognizing the need for better teaching prosections in podiatric education, we developed a chemical application method with underwater dissection to better preserve anatomic structures of the cadaveric foot and ankle. METHODS: We used inexpensive chemicals before, during, and after each step, which ultimately resulted in high-quality prosections that improved identification of anatomic structures relevant to the practice of podiatric medicine. RESULTS: Careful preservation of clinically important nerves, vessels, muscles, ligaments, and joints was achieved with these prosections. CONCLUSIONS: Although this method required additional preparation time, the resultant prosections have been repeatedly used for several years to facilitate learning among podiatry students and residents, and they have held up well. This method can be used by educators to teach podiatry students throughout their medical training and even into residency.

Psychometric properties and podiatric medical student perceptions of USMLE-style items in a general anatomy course.

BACKGROUND: In 2010, the New York College of Podiatric Medicine general anatomy course was redesigned to emphasize clinical anatomy. Over a 2-year period, United States Medical Licensing Examination (USMLE)-style items were used in lecture assessments with two cohorts of students (N =200). Items were single-best-answer and extended-matching formats. Psychometric properties of items and assessments were evaluated, and anonymous student post-course surveys were administered. METHODS: Mean grades for each assessment were recorded over time and compared between cohorts using analysis of variance. Correlational analyses were used to investigate the relationship between final course grades and lecture examinations. Post-course survey response rates for the cohorts were 71 of 97 (73%) and 81 of 103 (79%). RESULTS: The USMLE-style items had strong psychometric properties. Point biserial correlations were 0.20 and greater, and the range of students answering the items correctly was 25% to 75%. Examinations were highly reliable, with Kuder-Richardson 20 coefficients of 0.71 to 0.76. Students (>80%) reported that single-best-answer items were easier than extended-matching items. Students (>76%) believed that the items on the quizzes/examinations were similar to those found on USMLE Step 1. Most students (>84%) believed that they would do well on the anatomy section of their boards (American Podiatric Medical Licensing Examination [APMLE] Part I). CONCLUSIONS: Students valued USMLE-style items. These data, coupled with the psychometric data, suggest that USMLE-style items can be successfully incorporated into a basic science course in podiatric medical education. Outcomes from students who recently took the APMLE Part I suggest that incorporation of USMLE-style items into the general anatomy course was a successful measure and prepared them well.

The transverse occipital ligament: an anatomic, histologic, and radiographic study.

BACKGROUND CONTEXT: The craniocervical region is an osteoligamentous complex that provides structural stability and movement by means of numerous ligaments. Fundamental knowledge of these ligaments is important for physicians who treat patients with disorders of this region to reduce morbidity and mortality. There is a paucity of data in the literature regarding the morphology, function, and classification of the transverse occipital ligament (TOL). PURPOSE: The purpose of this study was to investigate the prevalence, morphology, and variations of the TOL in a large number of adult human cadavers using dissection, histology, and digital radiography. STUDY DESIGN: Cadaveric laboratory study. SAMPLE: Thirty-two formalin-fixed human adult cadavers were dissected in the study. Fourteen cadavers were found to have a TOL. OUTCOME MEASURES: Measurements using a digital caliper, high-resolution digital photography, histologic staining with bright-field microscopy, and digital radiography. METHODS: The posterior musculature and related soft tissues were dissected and underlying bony elements removed. The TOL was identified, isolated, measured, and then removed for histologic preparation with hematoxylin and eosin staining. Anteroposterior open-mouth digital radiographs of the upper cervical spine with monofilament attached to the TOL were used to demonstrate its relations to the occiput, atlas, and axis. RESULTS: The TOL was present in 14 of 32 (44%) of the dissected cadavers (six male and eight female). Three types of TOLs were identified. Type 1 had bilateral connections to the alar ligaments and had fibers inserting onto the dens. Type 2 also had bilateral connections to the alar ligaments but did not have fibers inserting onto the dens. Type 3 neither had any connections to the alar ligaments nor had fibers that connected to the dens. Male cadavers always had a Type 1 TOL compared with 3 of 8 (38%) female cadavers and this difference was significant (p=.031). The TOL consisted of dense regular connective tissue with parallel arrangements of collagen fibers and interposed fibroblasts. CONCLUSIONS: Our data suggest that the TOL is not an anatomic variant and can be classified into three types. Future biomechanical studies can be designed to investigate the function of the TOL, although we hypothesize that it may act as a fulcrum during flexion and extension of the head because it is located between the apical ligament and superior crus of the cruciform ligament. Anteroposterior open-mouth digital radiographs revealed the location of the TOL with respect to the upper two cervical vertebrae. Future research should investigate the radiologic characteristics of the TOL using magnetic resonance imaging.