Sexual dimorphism in articular tissue anatomy - Key to understanding sex differences in osteoarthritis?

OBJECTIVE: Osteoarthritis (OA) prevalence and incidence varies between women and men, but it is unknown whether this follows sex-specific differences in systemic factors (e.g. hormones) and/or differences in pre-morbid joint anatomy. We recognize that classifications of sex within humans cannot be reduced to female/male, but given the lack of literature on non-binary individuals, this review is limited to the sexual dimorphism of articular morphotypes. METHODS: Based on a Pubmed search using relevant terms, and input from experts, we selected articles based on the authors' judgment of their relevance, interest, originality, and scientific quality; no "hard" bibliometric measures were used to evaluate their quality or importance. Focus was on clinical rather than pre-clinical studies, with most (imaging) data being available for the knee joint. RESULTS: After introducing "sexual dimorphism", the specific literature on articular morphotypes is reviewed, structured by: radiographic joint space width (JSW), meniscus, ligaments, articular cartilage morphology, articular cartilage composition and deformation, and articular tissue response to treatment. CONCLUSIONS: Sex-specific differences were clearly observed for JSW, meniscus damage, ligament size, and cartilage morphometry (volume, thickness, and surface areas) but not for cartilage composition. Ligament and cartilage measures were smaller in women even after matching for confounders. Taken together, the findings indicate that female (knee) joints may be structurally more vulnerable and at greater risk of OA. The "one size/sex fits all" approach must be abandoned in OA research, and all observational and interventional studies should report their results for sex-specific strata, at least in pre-specified secondary or post-hoc analyses.

Editorial Commentary: When Managing Patellofemoral Instability, Mind Your P's and Q's: Medial Patellofemoral Ligament Versus Medial Quadriceps Tendon Femoral Ligament Versus Medial Patellofemoral Complex.

Our understanding of patellar instability and the medial patellofemoral complex (MPFC) has evolved over the past 15 years. Despite advancements and appreciation of the anatomy and biomechanics of the MPFC, the best surgical treatment for recurrent patellar instability has yet to be determined. The goals of medial patellofemoral ligament (MPFL), medial quadriceps tendon femoral ligament (MQTFL), or MPFC reconstructions (with grafts from both the patella and quad to the femur) are to return patients back to activity and avoid complications such as recurrent instability, overconstraint, secondary arthrosis, and potential patellar fracture from surgical drill holes. Other considerations when managing recurrent instability include patella alta, hypermobility, and whether an osteotomy procedure is indicated. Although we always need to make good choices and mind our P's and Q's, the big question remains: Is MPFL, MQTFL, or MPFC the best choice for our patients?

Morphological and morphometric analysis of oblique popliteal ligament in North Indian population: a cadaveric study.

PURPOSE: To study the morphology and the morphometry of the oblique popliteal ligament (OPL). METHODS: Thirty cadaver knees were dissected to study the morphology and morphometry of the OPL. For the measurement of the morphology of the OPL a standard tape and the vernier callipers were used. RESULT: Out of 30 specimens 14 were Y shaped, 10 were band shaped, and 6 were Z shaped observed. Total length was measured on both the limbs, on the right side it was 4.5 ± 0.4 cm and on the left side 4.5 ± 0.5 cm was recorded. Width at the medial attachment was also measured on both the limbs, on the right side it was 4.6 ± 0.5 cm and on the left side 4.7 ± 0.5 cm was recorded. And width at the lateral attachment was recorded too, on the right side it was 4 ± 0.3 cm and on the left side it was 4 ± 0.3 cm. Width at the midpoint was recorded as on the right side 3.5 ± 0.2 cm and on the left side 3.5 ± 0.2 cm. CONCLUSION: The OPL is a thick ligament that arises as an extension of the semimembranosus, and it exists in various morphology which includes band, Y, Z, complex shapes.

Anatomical analysis of ligaments surrounding calcaneocuboid joint; implications for role in foot stability.

PURPOSE: The calcaneocuboid joint is located in the lateral part of the foot and acts as a major stabilizer for the foot. Injuries to this joint often occur in association with ankle or foot injuries and are frequently overlooked, subsequently causing chronic pain or osteoarthritis. However, the relationship between ligaments surrounding the joint and joint instability remains unclear. Therefore, this study aimed to clarify the morphology and position of the ligaments surrounding the calcaneocuboid joint, and to reveal the relationship between the ligament structure. METHODS: The position and morphology of the bifurcate ligament (subdivided into calcaneonavicular and calcaneocuboid ligaments), dorsal calcaneocuboid ligament, lateral calcaneocuboid ligament, long plantar ligament, and short plantar ligament were measured (N = 11 feet in 6 Japanese cadavers). The circumference of the joint was quartered, while the ligament-uncovered area and the estimated cross-sectional area of each ligament were compared between the four sides. Furthermore, the estimated cross-sectional area of each ligament was calculated as an index for the ligament strength. RESULTS: The inferolateral side of the calcaneocuboid joint had the most uncovered area (54.63%) by the ligaments. In addition, the cross-sectional area of the ligaments on the lateral side was considerably smaller than that on the medial side. CONCLUSION: Our results suggest that ligament weakness on the inferolateral side may cause instability of the calcaneocuboid joint, especially after an inversion sprain injury, and may decrease the lateral longitudinal arch function, which results in chronic foot pain.

Does ponticulus posticus affect vertebral artery diameter.

PURPOSE: Ponticulus Posticus, atlantooccipital ligament ossification-induced anomaly, surrounds the vertebral artery and the first cervical nerve root. It is believed to wrap around the first cervical nerve root and the vertebral artery, causing compression. We hypothesized that it would also reduce the diameter of the vertebral artery. METHODS: Between January 1, 2022, and December 31, 2022, cervical spine CT scans taken for any reason were retrospectively reviewed. The images of 1365 patients suitable for evaluation were evaluated by two expert radiologists in 3 dimensions. Among patients with PP, those who underwent cervical angiography were identified for vertebral artery diameter measurement. RESULTS: The average age of the 1365 individuals included in the study (732 males, 633 females) was 55.78 (± 18.85) with an age range of 1-96. Among this group, PP was detected in 288 individuals, resulting in a total prevalence of 21.1%. Right and left vertebral artery diameters were significantly lower in patients with complete PP compared to the absent group (p < 0,001, p < 0,001, respectively). Additionally, it was observed that width and height diameters and artery diameters were positively correlated in patients with Complete PP. CONCLUSIONS: Ponticulus posticus can cause vertebrobasilar insufficiency by reducing the diameter of the vertebral artery. Therefore, imaging and detailed evaluation of this region are important in symptomatic patients.

Medial Patellofemoral Reconstruction Techniques for Patellar Instability.

The medial patellofemoral complex (MPFC) is the term used to describe the primary soft tissue stabilizer of the patella, which consists of fibers that attach to the patella (medial patellofemoral ligament, or MPFL), and the quadriceps tendon (medial quadriceps tendon femoral ligament, or MQTFL). Despite the variability of its attachment on the extensor mechanism, the midpoint of this complex is consistently at the junction of the medial quadriceps tendon with the articular surface of the patella, indicating that either patellar or quadriceps tendon fixation can be used for anatomic reconstruction. Multiple techniques exist to reconstruct the MPFC, including graft fixation on the patella, quadriceps tendon, or both structures. Various techniques using several graft types and fixation devices have all reported good outcomes. Regardless of the location of fixation on the extensor mechanism, elements critical to the success of the procedure include anatomic femoral tunnel placement, avoiding placing undue tension on the graft, and addressing concurrent morphological risk factors when present. This infographic reviews the anatomy and techniques for the reconstruction of the MPFC, including graft configuration, type, and fixation, while addressing common pearls and pitfalls in the surgical treatment of patellar instability.

Anatomy and morphology of iliolumbar ligament.

PURPOSE: To address limited amount of available data and contradictory statements in published works 60 Iliolumbar ligaments extracted from 30 cadavers were examined to describe their insertions and morphology. METHODS: The ligaments were removed during the standard autopsy procedures with a use of an oscillating saw, a chisel and a scalpel. The specimens were photographed before the extraction and measured alongside their anterior margin. Next, they were preserved in formaldehyde, stripped of other soft tissues and then examined, photographed and described. RESULTS: The mean length of the ligaments was 31.7 mm. 44 specimens were described as single-banded, 13 as double-banded and 3 as other. In 24 cases costal process of LV has been fixed to the iliac plate by short ligamentous bands. In 38 cases there was a thick fibrous membrane connected to the ligament. No legitimate insertions on LIV vertebra were observed. CONCLUSIONS: Typical iliolumbar ligament consists of a single ligamentous band. Most common variability of the ligament consist of two bands. In approximately 40% of cases the costal process of LV can be additionally stabilized to the iliac plate by short, strong ligamentous bands. In 63% of cases a connection between the iliolumbar ligament and a fibrous membrane placed in the frontal plane, superiorly to the ligament, has been observed. There seems to be no convincing proof of existence of the insertion of the iliolumbar ligament on the LIV vertebra.

Medial patellofemoral ligament is a part of the vastus medialis obliquus and vastus intermedius aponeuroses attaching to the medial epicondyle.

PURPOSE: This study aimed to investigate the bony surface characteristic of the femoral attachment of the medial patellofemoral ligament (MPFL) and the correlation between the relevant layered structures, including muscular aponeurosis and the joint capsule, which contribute to patellofemoral joint (PFJ) stability. METHODS: The morphology of the medial aspect of the medial condyle using micro-computed tomography and analysed cortical bone thickening in 24 knees was observed. For the macroscopic and histological analyses, 21 and 3 knees were allocated, respectively. The Kruskal-Wallis one-way analysis of variance test with Dunn post hoc testing was performed for statistical analysis. RESULTS: At the level of the adductor tubercle, there were no significant differences in cortical bone thickness. At the level of the medial epicondyle (MEC), cortical bone thickness was considerably greater than that in other areas of the medial condyle (mean ± standard deviation, 0.60 ± 0.20 mm; p < 0.0001). Macroscopic analysis revealed that the deep aponeurosis of the vastus medialis obliquus and the tendinous arch of the vastus intermedius distally formed the composite membrane and adjoined to the joint capsule to firmly attach to MEC, which was located at 41.3 ± 5.7 mm posterior and 14.2 ± 3.1 mm superior to the joint cartilage. Histological analysis showed a composite membrane and adjoining capsule attached to MEC via fibrocartilage. CONCLUSION: MPFL could be interpreted as part of the deep aponeurosis of the vastus medialis obliquus (VMO) and the tendinous arch of the vastus intermedius, which combined with the joint capsule to attach to MEC. The cortical bone thickening indicated that the tensile stresses were loaded on MEC in aged cadavers. Involvement of VMO and vastus intermedius aponeuroses in restored graft of MPFL could utilise the dynamic stability of surrounding muscles to mimic a native structure.

MRI evaluation of the peripheral attachments of the lateral meniscal body: the menisco-tibio-popliteus-fibular complex.

PURPOSE: To determine, identify and measure the structures of the menisco-tibio-popliteus-fibular complex (MTPFC) with magnetic resonance imaging (MRI) in knees without structural abnormalities or a history of knee surgery. METHODS: One-hundred-and-five knees without prior injury or antecedent surgery were analyzed by means of MRI. The average age was 50.1 years ± 14.8. All the measurements were performed by three observers. The peripherical structures of the lateral meniscus body were identified to determine the location, size, and thickness of the entire MTPFC. The distance to other "key areas" in the lateral compartment was also studied and compared by gender and age. RESULTS: The lateral meniscotibial ligament (LMTL) was found in 97.1% of the MRIs, the popliteofibular ligament (PFL) in 93.3%, the popliteomeniscal ligaments (PML) in 90.4% and the meniscofibular ligament (MFL) in 39%. The anteroposterior distance of the LMTL in an axial view was 20.7 mm ± 3.9, the anterior thickness of the LMTL was 1.1 mm ± 0.3, and the posterior thickness of the LMTL 1.2 mm ± 0.1 and the height in a coronal view was 10.8 mm ± 1.9. The length of the PFL in a coronal view was 8.7 mm ± 2.5, the thickness was 1.4 mm ± 0.4 and the width in an axial view was 7.8 mm ± 2.2. CONCLUSIONS: The MTPFC has a constant morphological and anatomical pattern for three of its main ligaments and can be easily identified and measured in an MRI; the MFL has a lower prevalence, considering a structure difficult to identify by 1.5 T MRI.

Surgical Anatomy for Fibular Free Flap Focusing on the Inferior Tibiofibular Syndesmotic System: A Cadaveric Study and Case Series of 3-Dimensional Prefabricate Cutting Guided Fibular Free Flap.

ABSTRACT: Even though there are many options for mandibular reconstruction, a free fibula osteocutaneous flap is regarded as the most frequently used flap. Despite having some previous anatomical studies pertaining to syndesmotic ligaments, there is no study pointing out that surgical landmarks can be used while free fibula osteocutaneous flaps are performed and used for surgical landmarks in order to avoid syndesmotic ligament injuries. Therefore, this study investigates the characteristics and relationship between inferior syndesmotic ligaments and fibula in cadavers. A total of 140 legs were obtained from 83 embalmed cadavers as well as other soft ones, which were donated for the inferior tibiofibular syndes- motic system's study. Detailed dissection and measurement of each ligament's distance to the end of the fibula and lateral malleolus were performed. Distances from the distal end of the fibula to anterior inferior tibiofibular ligament, posterior inferior tibiofibular, and inferior transverse ligament, and the lower border of the interosseous membrane are 3.5 ±â€Š0.4 cm, 3.4 ±â€Š0.5 cm, 1.9 ±â€Š0.4 cm, and 5 ±â€Š1 cm (mean ±â€ŠSD), respectively. Distance from the most distal part of the fibula to lateral malleolus is 1.6 ±â€Š0.4 cm (mean ±â€ŠSD). Thus, the remaining distance of the fibular should be left at least 4 cm without disrupting the syndesmotic ligament complex. It is argued that the lateral malleolus can be applied as a surgical landmark while harvesting fibula.

The association between coracoacromial ligament morphology and rotator cuff tears: A cadaveric study.

To determine the association between coracoacromial ligament (CAL) morphology and rotator cuff tears. The present study is a prospective cohort study based on the dissection of 172 shoulders from 86 (46 female, 40 male) formalin embalmed European Caucasian cadavers, with a median age of 82 years. The anatomy of CAL was examined, including its morphology and parametric measurements, while the rotator cuff tendons were inspected for the presence of tears. Gross examination of the CAL in 155 shoulders revealed a variable number of bands as follows: 28 (18%) had one band, 56 (36%) two bands and 71 (46%) three or more bands. Inspection of the rotator cuff tendons showed the presence of tears in 77 (50%) shoulders, of which 37 (24%) were partial and 40 (26%) were full-thickness tears. Statistical analysis showed a significant association (P < 0.05) between CAL band number and the prevalence of a rotator cuff tear. A high proportion of rotator cuff tears were observed in shoulders with two (52%) and three or more CAL bands (56%) compared to single band ligaments (29%). Parametric assessment of the CAL in shoulders with rotator cuff tears showed significantly greater (P < 0.05) attachment widths and ratios, thicker ligament bands, and larger cross-sectional areas compared to the control group. Coracoacromial ligaments with more than a single band have a strong association with rotator cuff tears.

Distal tibiofibular syndesmosis: A meta-analysis of cadaveric studies.

Though injuries to the distal tibiofibular (DTF) syndesmosis are commonly encountered in orthopedic and trauma settings, its anatomical structures have been poorly researched. The commonly overlooked DTF ligament injuries are known to cause chronic ankle pain, instability and post-traumatic osteoarthritis. Quantitative and morphological evidence synthesis has not been yet conducted. A meta-analysis was conducted to collect data from morphological studies to document more accurate details on the prevalence, size, and insertion sites of its components. The Checklist for Anatomical Reviews and Meta-Analyses (CARMA) was followed. Ten studies met the inclusion criteria with a total of 265 investigated ankles. The analysis demonstrated that the anterior and posterior tibiofibular ligaments along with the interosseous ligament were present in 100% of joints. The inferior transverse tibiofibular and the distal fascicle of the anterior tibiofibular ligament were the least prevalent with frequencies of 96% and 86.5%, respectively. The inferior transverse ligament was recorded as the longest ligament. The widest ligament was found to be the interosseous tibiofibular ligament at its fibular attachment. The thickest of the ligamentous components was the posterior tibiofibular ligament. While more cadaveric research is warranted, these results would help directing future biomechanical investigations and planning new research to further aid in diagnostic and therapeutic approaches to the injuries of the distal tibiofibular syndesmosis.

Anatomical and biomechanical evaluation of the lateral calcaneo-cuboid and bifurcate ligaments.

BACKGROUND: This study aims to analyze the ligaments of the dorso-lateral calcaneo-cuboid joint and to assess the biomechanical relevance of the bifurcate ligament. METHODS: 16 specimens were analyzed for their ligamentous anatomy of the dorso-lateral calcaneo-cuboid joint and side-alternating assigned to two groups with varying ligamentous dissection order. The Chopart joint was stressed in plantar, medial, and lateral direction measuring the displacement by an 3D motion tracker for every dissection step. RESULTS: 37.5% of specimens had all ligaments (lateral calcaneo-cuboid, dorsal calcaneo-cuboid, bifurcate calcaneo-cuboid, bifurcate calcaneo-navicular), 37.5% were lacking bifurcate´s calcaneo-cuboid-portion, and 25% presented without dorsal calcaneo-cuboid. Biomechanical testing revealed no significant displacement within the calcaneo-cuboid or talo-navicular joint for any stressed state except for axial compression with dissected dorsal talo-navicular joint capsule in Group 2. CONCLUSION: Broad morphological variability and missing significant displacement regardless of its integrity, make the bifurcate ligament appear of limited biomechanical relevance.

Anatomy and Correlation of the Coracoid Process and Coracoclavicular Ligament Based on Three-Dimensional Computed Tomography Reconstruction and Magnetic Resonance Imaging.

BACKGROUND The anatomy of the coracoid process and coracoclavicular (CC) ligament have been described and the correlation between them has been assessed based on 3-dimensional computed tomography (CT) reconstruction and magnetic resonance imaging (MRI), which provide a guide for coracoclavicular ligament reconstruction. MATERIAL AND METHODS Data were collected from 300 patients who underwent both CT and MRI of the shoulder joint from January 2017 to January 2019 at the Jiang'an Hospital of Traditional Chinese Medicine. The coracoid process was observed and classified and parameters of the CC ligament were measured according to different corneal types. All of the statistics were collected and classified by 2 radiologists, and average values were determined.Measurements of segments were taken as follows: ab - In the coronal plane, the length of the CC ligament from the central point of the CC ligament at the clavicular attachment to the CC ligament at the center of the CC attachment); ac - The distance from the center point of the CC ligament at the supraclavicular attachment to the acromioclavicular joint; de - In the sagittal plane, the length of the CC ligament from the center of the clavicular attachment to the coracoid attachment point; fg - The maximum diameter of the CC ligament at the anterior and posterior margins of the clavicle attachment; hi - The largest diameter of the CC ligament at the anterior and posterior edge of the coracoid process attachment; dj - The distance of the coracoclavicular ligament from the center point of the coracoid process attachment to the coracoid process tip; kl - The distance in the supraclavicular plane from the coracoclavicular ligament to the subcoracoid process. RESULTS The analysis showed that there are 5 types of coracoid process: gourd (31%), short rod (20%), long rod (22.3%), wedge (10.3%), and water drop (6.3%). There were statistically significant differences between the lengths of the ac and hi segments in the among the wedge and gourd-type and the short rod and water drop-type coracoid processes. There were statistically significant differences between the lengths of the ab, de, and fg segments in the short rod, gourd, and long rod-type coracoid processes. There were statistically significant differences between the lengths of the ac, fg, hi, dj, and kl segments in the water drop, gourd, and long rod-type coracoid processes. CONCLUSIONS The present study indicated that measurement of the CC ligament and the different shapes of the coracoid process provide an anatomical basis for the diagnosis and treatment of shoulder diseases and the data can be used to improve the safety of CC ligament reconstruction.

An Unrecognized Ligament and its Ossification in the Craniocervical Junction: Prevalence, Patient Characteristics, and Anatomic Evidence.

BACKGROUND: In the craniocervical junction, the ligaments between the anterior foramen magnum and the anterior arch of the atlas are not well defined, and ossification of the ligaments in this region has rarely been reported. Characterizing the anatomy and ossification of these ligaments may help in the diagnosis and treatment of disorders in this region. QUESTIONS/PURPOSES: (1) What is the prevalence of an unrecognized ossification at the craniocervical junction in patients with cervical spine disorders, and what are the patient characteristics associated with this ossification? (2) Do patients with this ossification have a greater risk of ossification of other structures at the craniocervical junction or cervical spine? (3) Is there an unreported ligament at this ossified site? METHODS: We conducted a retrospective study of 578 hospitalized patients who underwent CT for cervical spine disorders between January 2016 and July 2020. Based on the inclusion criteria, 11% (66 of 578) were excluded because of a cervical or craniocervical tumor, deformity, infection, fracture or dislocation, or prior surgery, leaving 89% (512 of 578) for analysis. These 512 patients had diagnoses of cervical radiculopathy, cervical myelopathy, cervical spondylotic amyotrophy, cervical spinal cord injury without a radiographic abnormality, or axial neck pain. Their mean age was 57 years (range 22-90 years), and 60% of the patients were men. Patient characteristics including age, gender, and diagnosis were retrieved from a longitudinally maintained institutional database. CT images were used to assess the presence of a previously unrecognized ossification and ossification of other structures in the craniocervical junction and cervical spine, including the posterior longitudinal ligament, anterior longitudinal ligament, nuchal ligament, ligamentum flavum, transverse ligament, and apical ligament, as well as diffuse idiopathic skeletal hyperostosis (DISH). The association between these structures was also assessed. This unreported ossification was called the capped dens sign. It was defined and graded from 1 to 3. Grade 3 was defined as the typical capped dens sign. Cervical spine MRI was used to assess whether there was an unreported structure in the same region as where the capped dens sign was detected on CT images. In the database of a recent study, there were 33 patients younger than 41 years. Nine percent (three of 33) were excluded because they did not have cervical spine MRI. MRIs of the remaining 30 patients were assessed. Their mean age was 35 years (range 22-40 years), and 58% were men. All cervical spine CT images and MRIs were reviewed by one senior spine surgeon and one junior spine surgeon twice with a 2-week interval. Blinding was accomplished by removing identifying information from the radiographs and randomly assigning them to each examiner. Any discrepancy with respect to the grade of the capped dens sign was adjudicated by a third blinded senior spine surgeon. Intrarater and interrater reliabilities were assessed by calculating weighted kappa statistics. No ligament or membrane was reported at this site. MRI is not sensitive to identify thin tissue in this region, especially when severe degeneration has occurred. A cadaveric study was conducted to discover a potential ligament between the inferior margin of the foramen magnum and the anterior arch of the atlas, as prompted by the newly discovered ossification in the clinical analysis of this study. Six embalmed human cadaveric craniocervical regions (three male and three female cadavers; median age 56 years, range 45-78 years) were dissected by a senior anatomist and a senior anatomy technician. A mid-sagittal section of the craniocervical junction was created, allowing us to explore the interval between the anterior foramen magnum and anterior arch of the atlas. A histologic analysis was conducted in two of the six cadavers (a male cadaver, 45 years; and a female cadaver, 51 years). Slides were made with 4-µm sections and stained with hematoxylin and eosin. RESULTS: A novel capped dens sign was detected in 39% (198 of 512) of the patients and the most typical capped dens sign was detected in 19% (96 of 512) of patients. The prevalence of this sign was the highest in patients with cervical spondylotic amyotrophy (12 of 25 patients). The prevalence of ossification of the anterior longitudinal ligament, ligamentum nuchae, and apical ligament, as well as DISH, was higher in patients with a capped dens sign than in those without (p = 0.04, p < 0.001, p < 0.001, and p = 0.001, respectively). The capped dens sign was identified in 69% (18 of 26) of the patients with DISH. A thin and short band-like structure or osteophyte was detected on MRI in 87% (26 of 30), in the same region as the capped dens sign. In the cadaveric study, an unreported, distinct ligamentous structure was identified at this ossified site. It originated from the posterosuperior rim of the anterior arch of the atlas to the inferior margin of the foramen magnum, which we called the inter-atlanto-occipital ligament. It was found in all six dissected craniocervical junctions. The histologic analysis revealed dense connective tissue. CONCLUSION: More than one-third of the patients in this series demonstrated CT evidence of a previously unrecognized ossification in the craniocervical junction, which we called the capped dens sign. Anatomic evidence of this sign, which was a previously unidentified ligament, was also newly discovered in this region. This study was conducted among Asian patients and specimens. Further studies among diverse ethnic groups may be needed to generalize the results. An additional well-designed prospective study will be needed to provide further evidence regarding the potential pathophysiology and clinical relevance of the capped dens sign. Furthermore, the cadaveric analysis in this study was only a preliminary report of the ligament; further biomechanical research is needed to investigate its function. CLINICAL RELEVANCE: Knowledge of this novel ligament may improve the diagnosis and treatment of craniocervical stability and dislocation. Ossification of this ligament is correlated with age, cervical spondylotic amyotrophy, and DISH. We wonder whether patients with cervical degenerative disorders who also have a capped dens sign may be at risk for the formation of osteophytes of an uncovertebral joint, which may result in palsy of the upper limb muscles. The capped dens sign may be the craniocervical manifestation of DISH. This possible association between the capped dens sign and DISH should be considered when performing surgery on patients with the capped dens sign.

The Medial structures of the knee have a significant contribution to posteromedial rotational laxity control in the PCL-deficient knee.

PURPOSE: Various reconstruction techniques have been employed to restore normal kinematics to PCL-deficient knees; however, studies show that failure rates are still high. Damage to secondary ligamentous stabilizers of the joint, which commonly occurs concurrently with PCL injuries, may contribute to these failures. The main objective of this study was to quantify the biomechanical contributions of the deep medial collateral ligament (dMCL) and posterior oblique ligament (POL) in stabilizing the PCL-deficient knee, using a joint motion simulator. METHODS: Eight cadaveric knees underwent biomechanical analysis of posteromedial stability and rotatory laxity using an AMTI VIVO joint motion simulator. Combined posterior force (100 N) and internal torque (5 Nm) loads, followed by pure internal/external torques (± 5 Nm), were applied at 0, 30, 60 and 90° of flexion. The specimens were tested in the intact state, followed by sequential sectioning of the PCL, dMCL, POL and sMCL. The order of sectioning of the dMCL and POL was randomized, providing n = 4 for each cutting sequence. Changes in posteromedial displacements and rotatory laxities were measured, as were the biomechanical contributions of the dMCL, POL and sMCL in resisting these loads in a PCL-deficient knee. RESULTS: Overall, it was observed that POL transection caused increased posteromedial displacements and internal rotations in extension, whereas dMCL transection had less of an effect in extension and more of an effect in flexion. Although statistically significant differences were identified during most loading scenarios, the increases in posteromedial displacements and rotatory laxity due to transection of the POL or dMCL were usually small. However, when internal torque was applied to the PCL-deficient knee, the combined torque contributions of the dMCL and POL towards resisting rotation was similar to that of the sMCL. CONCLUSION: The dMCL and POL are both important secondary stabilizers to posteromedial translation in the PCL-deficient knee, with alternating roles depending on flexion angle. Thus, in a PCL-deficient knee, concomitant injuries to either the POL or dMCL should be addressed with the aim of reducing the risk of PCL reconstruction failure.

Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics.

The posterior cruciate ligament (PCL) represents an intra-articular structure composed of two distinct bundles. Considering the anterior and posterior meniscofemoral ligaments, a total of four ligamentous fibre bundles of the posterior knee complex act synergistically to restrain posterior and rotatory tibial loads. Injury mechanisms associated with high-energy trauma and accompanying injury patterns may complicate the diagnostic evaluation and accuracy. Therefore, a thorough and systematic diagnostic workup is necessary to assess the severity of the PCL injury and to initiate an appropriate treatment approach. Since structural damage to the PCL occurs in more than one third of trauma patients experiencing acute knee injury with hemarthrosis, background knowledge for management of PCL injuries is important. In Part 1 of the evidence-based update on management of primary and recurrent PCL injuries, the anatomical, biomechanical, and diagnostic principles are presented. This paper aims to convey the anatomical and biomechanical knowledge needed for accurate diagnosis to facilitate subsequent decision-making in the treatment of PCL injuries.Level of evidence V.

Innervation of the wrist joint: Literature review and clinical implications.

The aim of this study was to review the literature on the innervation of the wrist with an emphasis on pathological and therapeutic aspects. The nerves involved in wrist innervation and their mechanoreceptor endings are described. The literature over the past 30 years includes several topics that are still subjects of discussion and debate and require further research.

The glenohumeral ligaments: Superior, middle, and inferior: Anatomy, biomechanics, injury, and diagnosis.

The three glenohumeral ligaments (superior, middle, and inferior) are discrete thickenings of the glenohumeral joint capsule and are critical to shoulder stability and function. Injuries to this area are a cause of significant musculoskeletal morbidity. A literature search was performed by a review of PubMed, Google Scholar, and OVID for all relevant articles published up until 2020. This study highlights the anatomy, biomechanical function, and injury patterns of the glenohumeral ligaments, which may be relevant to clinical presentation and diagnosis. A detailed understanding of the normal anatomy and biomechanics is a necessary prerequisite to understanding the injury patterns and clinical presentations of disorders involving the glenohumeral ligaments of the shoulder.

Anatomical evaluation of the femoral attachment of the posterior oblique ligament.

INTRODUCTION: Tibiofemoral joint instability reduces patient satisfaction after total knee arthroplasty (TKA). However, surgeons sometimes encounter excessive medial joint laxity without medial over-release on the tibial side. It was hypothesized that over-resection of the posteromedial femoral condyle can injure the medial stabilizers, especially the posterior oblique ligament (POL) at its femoral attachments. MATERIALS AND METHODS: Thirteen fixed cadaveric knees were exposed, and 3 anatomical points were identified: the posterior edge and midpoint of the POL femoral attachment, and the posterior edge of the superficial medial collateral ligament (sMCL) femoral attachment. The distance from the surface of the posteromedial femoral condyle to each point was measured. Correlations between each point and the anterior-posterior or medial-lateral dimensions of the distal femur were also calculated. RESULTS: The average distances to the posterior edge and midpoint of the POL femoral attachment and the posterior edge of the sMCL femoral attachment were 13.7 mm (9.0-18.4), 17.9 mm (11.5-22.6), and 22.7 mm (14.7-29.4), respectively. There were moderate correlations between the distance to each point and the anterior-posterior or medial-lateral dimensions of the distal femur. CONCLUSIONS: The minimal distance from the surface of the posteromedial condyle to the POL posterior edge was 9.0 mm. Over-resection of the posteromedial femoral condyle, even with a general TKA femoral component, might injure the POL at its femoral attachments, especially in patients with small distal femurs, while the sMCL is rarely damaged. LEVEL OF EVIDENCE: Level IV.