Ligament Function Research Articles

Hip capsule biomechanics after arthroplasty

The hip's capsular ligaments passively restrain extreme range of movement (ROM) by wrapping around the native femoral head/neck. We determined the effect of hip resurfacing arthroplasty (HRA), dual-mobility total hip arthroplasty (DM-THA), conventional THA, and surgical approach on ligament function. Eight paired cadaveric hip joints were skeletonized but retained the hip capsule. Capsular ROM restraint during controlled internal rotation (IR) and external rotation (ER) was measured before and after HRA, DM-THA, and conventional THA, with a posterior (right hips) and anterior capsulotomy (left hips). Hip resurfacing provided a near-native ROM with between 5° to 17° increase in IR/ER ROM compared with the native hip for the different positions tested, which was a 9% to 33% increase. DM-THA generated a 9° to 61° (18% to 121%) increase in ROM. Conventional THA generated a 52° to 100° (94% to 199%) increase in ROM. Thus, for conventional THA, the capsule function that exerts a limit on ROM is lost. It is restored to some extent by DM-THA, and almost fully restored by hip resurfacing. In positions of low flexion/extension, the posterior capsulotomy provided more normal function than the anterior, possibly because the capsule was shortened during posterior repair. However, in deep flexion positions, the anterior capsulotomy functioned better. Native head-size and capsular repair preserves capsular function after arthroplasty. The anterior and posterior approach differentially affect postoperative biomechanical function of the capsular ligaments. Cite this article: Bone Joint J 2019;101-B:426-434.

Necessity of early correction of anal-coccygeal ligaments in traumatic damage to a coccyx

In order to prevent and correct the defecation disorders after destruction of the anococcygeal ligament, the meth-od of restoring its functional capacity was proposed (Patent of Ukraine for Invention No. 115280 “Method for Coccyx Re-moving”).
 It is proved that the damaging effect in the area of the traction and contraction mechanism of action on the rectum in 90.0% leads to continence disorders due to changes in the size of the anorectal angle due to the persistent disorders of the anococcygeal ligament function. The developed special mathematical model of the anococcygeal ligament function testifies that, when it is destroyed, the change in the anorectal angle value may reach changes in its value up to ≈63°, which distorts the direction of the anal canal and the distal rectum. Restoration by simulating of the anatomical fixation of anococcygeal ligament connection after its damage creates conditions for resto-ration of its physiological functioning.

Function of ankle ligaments for subtalar and talocrural joint stability during an inversion movement \u2013 an in vitro study

BackgroundThe lateral ankle ligament complex consisting of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL) and the posterior talofibular ligament (PTFL) is known to provide stability against ankle joint inversion. As injuries of the ankle joint have been reported at a wide range of plantarflexion/dorsiflexion angles, the aim of the present study was to evaluate the stabilizing function of these ligaments depending on the sagittal plane positioning of the ankle joint.MethodsEight fresh-frozen specimens were tested on a custom-built ankle deflection tester allowing the application of inversion torques in various plantarflexion/dorsiflexion positions. A motion capture system recorded kinematic data from the talus, calcaneus and fibula with bone-pin markers during inversion movements at 10° of dorsiflexion, at neutral position and at plantarflexion 10°. ATFL, CFL and PTFL were separately but sequentially sectioned in order to assess the contribution of the individual ligament with regard to ankle joint stability.ResultsJoint- and position-specific modulations could be observed when the ligaments were cut. Cutting the ATFL did not lead to any observable alterations in ankle inversion angle at a given torque. But subsequently cutting the CFL increased the inversion angle of the talocrural joint in the 10° plantarflexed position, and significantly increased the inversion angle of the subtalar joint in the 10° dorsiflexed position. Sectioning of the PTFL led to minor increases of inversion angles in both joints.ConclusionsThe CFL is the primary ligamentous stabilizer of the ankle joint against a forced inversion. Its functioning depends greatly on the plantar−/dorsiflexion position of the ankle joint complex, as it provides the stability of the talocrural joint primarily during plantarflexion and the stability of the subtalar joint primarily during dorsiflexion.

Reducing Fear of Reinjury and Pain Perception in Athletes With First-Time Anterior Cruciate Ligament Reconstructions by Implementing Imagery Training.

Clinical Scenario: The anterior cruciate ligament is one of the major stabilizing ligaments of the knee joint by preventing anterior translation of the femur in the closed kinetic chain. A ruptured anterior cruciate ligament may require reconstructive surgery for patients who wish to return to physical activity. For the most part, surgeries are successful at repairing the ruptured ligament and restoring ligamentous function; the percentage of athletes that return to a competitive level of physical activity is only 44%, and 24% of patients report a main factor of preventing their return is fear of reinjury and pain. Most physiotherapy and rehabilitation research has focused on the physical treatment and is limited on the psychological aspects of recovery. Imagery has been suggested to be effective at reducing anxiety, tension, and pain, while promoting and encouraging healing after an injury. Imagery is defined as a process of performing a skill in one's mind using the senses (touch, feel, smell, vision, etc) without any overt actions. Clinical Question: In athletes who are first-time anterior cruciate ligament reconstruction patients, does imagery training in combination with standard physical therapy reduce the fear of reinjury and pain perception? Summary of Key Findings: Previous research has primarily looked at the physical treatment aspect, and few studies have focused on the psychological factors affecting recovery. Researchers concluded that fear of reinjury was the unique predictor of return to sport even in a sample of participants that reported very little or almost no pain at all. Imagery as a therapy is an effective intervention in reducing fear of reinjury and confidence building. Furthermore, mental imagery is suggested to assist with a reduction in anxiety, pain, and tension, while promoting healing. Clinical Bottom Line: Based on the strength of recommendation taxonomy, there is a combination of level A and B evidence proposing that imagery, in combination with traditional physical therapy, can be effective at reducing psychological distress such as fear of reinjury and pain perception in first-time anterior cruciate ligament reconstruction patients.

Effects of Cutting the Sacrospinous and Sacrotuberous Ligaments.

The sacrospinous (SS) and sacrotuberous (ST) ligaments form a complex at the posterior pelvis, with an assumed role as functional stabilizers. Experimental and clinical research has yielded controversial results regarding their function, both proving and disproving their role as pelvic stabilizers. These findings have implications for strategies for treating pelvic injury and pain syndromes. The aim of the present simulation study was to assess the influence of altered ligament function on pelvis motion. A finite elements computer model was used. The two-leg stance was simulated, with the load of body weight applied via the fifth lumbar vertebra and both femora, allowing for nutation of the sacroiliac joint. The in-silico kinematics were validated with in-vitro experiments using the same scenario of load application following SS and ST transection in six human cadavers. Modeling of partial or complete ligament failure caused significant increases in pelvis motion. This effect was most pronounced if the SS and ST were affected with 164% and 182%, followed by the sacroiliac and iliolumbar ligaments with 123% and 147%, and the pubic ligaments with 113% and 119%, for partial and complete disruption, respectively. Simultaneous ligament transection multiplied the effects on pelvis motion by up to 490%. Unilateral ligament injury altered the motion at the pelvis contralaterally. The experiments presented here provide strong evidence for the stabilizing role of the SS and ST. A fortiori, the instability resulting from partial or complete SS and ST injury merits consideration in treatment strategies involving these ligaments as important stabilizers. Clin. Anat. 32:231-237, 2019. © 2018 Wiley Periodicals, Inc.

Load transfer, damage, and failure in ligaments and tendons.

The function of ligaments and tendons is to support and transmit loads applied to the musculoskeletal system. These tissues are often able to perform their function for many decades; however, connective tissue disease and injury can compromise ligament and tendon integrity. A range of protein and non-protein constituents, combined in a complex structural hierarchy from the collagen molecule to the tissue and covering nanometer to centimeter length scales, govern tissue function, and impart characteristic non-linear material behavior. This review summarizes the structure of ligaments and tendons, the roles of their constituent components for load transfer across the hierarchy of structure, and the current understanding of how damage occurs in these tissues. Disease and injury can alter the constituent make-up and structural organization of ligaments and tendons, affecting tissue function, while also providing insight to the role and interactions of individual constituents. The studies and techniques presented here have helped to understand the relationship between tissue constituents and the physical mechanisms (e.g., stretching, sliding) that govern material behavior at and between length scales. In recent years, new techniques have been developed to probe ever smaller length scales and may help to elucidate mechanisms of load transfer and damage and the molecular constituents involved in the in the earliest stages of ligament and tendon damage. A detailed understanding of load transfer and damage from the molecular to the tissue level may elucidate targets for the treatment of connective tissue diseases and inform practice to prevent and rehabilitate ligament and tendon injuries. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3093-3104, 2018.

Capsular Ligament Function After Total Hip Arthroplasty

Background:The hip joint capsule passively restrains extreme range of motion, protecting the native hip against impingement, dislocation, and edge-loading. We hypothesized that following total hip arthroplasty (THA), the reduced femoral head size impairs this protective biomechanical function.Methods:In cadavers, THA was performed through the acetabular medial wall, preserving the entire capsule, and avoiding the targeting of a particular surgical approach. Eight hips were examined. Capsular function was measured by rotating the hip in 5 positions. Three head sizes (28, 32, and 36 mm) with 3 neck lengths (anatomical 0, +5, and +10 mm) were compared.Results:Internal and external rotation range of motion increased following THA, indicating late engagement of the capsule and reduced biomechanical function (p < 0.05). Internal rotation was affected more than external. Increasing neck length reduced this hypermobility, while too much lengthening caused nonphysiological restriction of external rotation. Larger head sizes only slightly reduced hypermobility.Conclusions:Following THA, the capsular ligaments were unable to wrap around the reduced-diameter femoral head to restrain extreme range of motion. The posterior capsule was the most affected, indicating that native posterior capsule preservation is not advantageous, at least in the short term. Insufficient neck length could cause capsular dysfunction even if native ligament anatomy is preserved, while increased neck length could overtighten the anterior capsule.Clinical Relevance:Increased understanding of soft-tissue balancing following THA could help to prevent instability and improve early function. This study illustrates how head size and neck length influence the biomechanical function of the hip capsule in the early postoperative period.

The Stabilising Effect of the Anterior Oblique Ligament to Prevent Directional Subluxation at the Trapeziometacarpal Joint of the Thumb: A Biomechanical Cadaveric Study.

The trapeziometacarpal joint (TMCJ) is inherently unstable, relying on ligament restraint to prevent subluxation. Subluxation of the thumb in a dorsoradial direction is often observed in clinical practice, either after acute ligament injury or more commonly with osteoarthritis (OA). This subluxation follows loss of function of trapeziometacarpal ligaments that stabilise this joint, resisting the deforming force of abductor pollicis longus (APL). The exact ligaments that stabilise and prevent the thumb from the pull of APL causing dorsoradial subluxation remain unknown, although the anterior oblique ligament (AOL) has been implicated. The aim of this study was to measure the direction of subluxation resisted by the AOL. In this study we used cadaveric limbs and custom made biomechanical testing to measure the influence AOL has in stabilising the thumb against subluxation in three planes: radial, dorsal and dorsoradial. Three fresh frozen hands were dissected to expose the TMCJ, leaving all ligaments, capsule and APL attachment in place. The force required to create a displacement of 5mm between the first metacarpal and the trapezium in these three planes was measured before and after AOL division. The average force to displace in the dorsoradial plane prior to division was 6.68N, and a statistically significant reduction to 1.15N (P<0.001) was found after division of the AOL. A statistically significant increase in force (P<0.001) from 2.89N to 4.04N was seen in the radial plane, while no change was seen dorsally (P=0.98), with average forces of 2.74N and 2.62N found pre and post division. There is clinical significance in reporting quantifiable data in this field, as subluxation of the thumb is often seen with OA. The results of our study provide support for surgical reconstruction of the AOL as the primary surgical stabilizer against dorsoradial subluxation of the thumb.Level of evidence: III.

Morphometric study of the posterior longitudinal ligament at the lumbar spine.

There are only two descriptions of posterior longitudinal ligament (PLL) at the lumbar spine level but its morphologic characteristics are different to cervical and thoracic levels. Spine explantation (from Th12 to L5) followed by resection of the neural arch and the dural sheath in 13 fresh cadavers was performed. The PLL was isolated from other epidural structures and its width was measured and compared to the vertebral body width at each vertebral levels. It was conducted at a microanatomic study concerning the PLL and the posterior outer annulus fibrosus. The PLL width was reduced craniocaudaly significantly, becoming thin from L4. The average width of PLL was 7.8mm at L1 and 1.9mm at L5. The width decreased gradually from L1 to L5 or abruptly from L4. The ratio of PLL width compared to the vertebral body width was 21% at L1 and 3% at L5. Microanatomic study confirmed that the PLL is less thick at its annulus fibrosus adhesion at L4-L5 and L5-S1. The relationship between the PLL and other epidural structures are discussed. The presence and function of the ilio-lumbar ligaments and the articular process orientation of L5-S1 may be explanations for PLL width decrease at L4-L5 and L5-S1. Furthermore, this aspect may be considered as one factor contributing to the occurrence of disc herniations at these levels, which levels are more frequently involved in this pathology.

New parameters describing how knee ligaments carry force in situ predict interspecimen variations in laxity during simulated clinical exams

Knee laxity, defined as the net translation or rotation of the tibia relative to the femur in a given direction in response to an applied load, is highly variable from person to person. High levels of knee laxity as assessed during routine clinical exams are associated with first-time ligament injury and graft reinjury following reconstruction. During laxity exams, ligaments carry force to resist the applied load; however, relationships between intersubject variations in knee laxity and variations in how ligaments carry force as the knee moves through its passive envelope of motion, which we refer to as ligament engagement, are not well established. Thus, the objectives of this study were, first, to define parameters describing ligament engagement and, then, to link variations in ligament engagement and variations in laxity across a group of knees. We used a robotic manipulator in a cadaveric knee model (n=20) to quantify how important knee stabilizers, namely the anterior and posterior cruciate ligaments (ACL and PCL, respectively), as well as the medial collateral ligament (MCL) engage during respective tests of anterior, posterior, and valgus laxity. Ligament engagement was quantified using three parameters: (1) in situ slack, defined as the relative tibiofemoral motion from the neutral position of the joint to the position where the ligament began to carry force; (2) in situ stiffness, defined as the slope of the linear portion of the ligament force–tibial motion response; and (3) ligament force at the peak applied load. Knee laxity was related to parameters of ligament engagement using univariate and multivariate regression models. Variations in the in situ slack of the ACL and PCL predicted anterior and posterior laxity, while variations in both in situ slack and in situ stiffness of the MCL predicted valgus laxity. Parameters of ligament engagement may be useful to further characterize the in situ biomechanical function of ligaments and ligament grafts.

Influence of Preoperative Range of Motion on Varus-Valgus Laxity in Total Knee Arthroplasty

In cases of TKA admitting flexion contracture, a treat to acquire soft tissue balance was required attention to the change throughout from full extension to flexion, because preoperative flexion contracture influenced on varus-valgus laxity after TKA at not only extended but also flexed knee position. Total knee arthroplasty (TKA) is one of the excellent treatments for osteoarthritis (OA) of knee. However varus and valgus stability of knee joint after TKA is important factor to improve patients’ quality of life, it remains unclear that what factors influence on varus-valgus laxity. It is assumed that there are many factors concerned with varus-valgus laxity, such as muscle strength, bony alignment, ligament function, implant design, and preoperative range of motion (ROM). In this study, we examined the influence of the flexion contracture on varus-valgus laxity in patients of OA of knee. A total of 42 knees underwent TKA using posterior stabilized (PS) type component by the measured resection method in our hospital were assessed in this study. The mechanical varus-valgus laxity was measured by the navigation system (precision N Knee Navigation Software v4.0; Stryker, Kalamazoo, Michigan) during operation at every 10° throughout the range of movement before and after implanted compornents. The objected knees divided into two groups, one was full extended group and the other was flexion contracture group. We analyzed two groups were compared using a non-parametric Mann-Whitney U test, and pre- and post-TKR comparisons were made using a non-parametric Wilcoxon signed-rank test. Analyses were performed with JMP statistical software v6.0 (SAS Institute, Tokyo, Japan). A p-value < 0.05 was considered to indicate statistical significance. We also evaluated correlation between preoperative ROM and postoperative varus-valgus laxity using the Spearman rank correlation coefficient. There was no significant difference of postoperative varus-valgus laxity between two groups. In the flexion contracture group, postoperative varus-valgus laxity were significantly greater than preoperative one at flexion of 10, 20, 30, 40, 50, and 60 degree. And the changing ratio of varus-valgus laxity in the flexion contracture group, which indicated postoperative varus-valgus laxity per preoperative one, were significantly greater than that in the full extended group at flexion of 80 and 90 degree. There were correlations between preoperative extension angle and changing ratio of varus-valgus laxity at flexion of 10, 20, 30, 60, and 90 degree. The rank correlation coefficient of Spearman were 0.36, 0.33, 0.33, 0.31, and 0.33 (p <0.05) each. In this study, it was observed influence of preoperative ROM on varus-valgus laxity not only at extended knee position but also at flexed knee position in the cases with flexion contracture after TKA. It suggested that treat of soft tissue to improve extension angle is involved varus-valgus laxity at flexed knee position. In cases admitting flexion contracture, a treat to acquire soft tissue balance was required attention to the change throughout from full extension to flexion.

3-Tesla MRI: Beneficial visualization of the meniscofemoral ligaments?

BackgroundRecent investigations have confirmed an important stabilizing and protective function of the meniscofemoral ligaments (MFLs) to the knee joint and suggest a clinical relevance. Concerning their incidences, however, there have been discrepancies between data acquired from cadaveric studies and MRI data using 0.3- to 1.5-Tesla field strengths probably due to lower resolution. This study aims to investigate whether imaging with 3-Tesla magnetic resonance imaging (3-T MRI) is beneficial in gaining information regarding the ligaments' incidence, length, width and anatomic variation. Methods3-T MRI images of 448 patients (224 males, 224 females, with, respectively, 32 patients of each sex in the age groups: 0–20, 21–30, 31–40, 41–50, 51–60, 61–70, >70years) were retrospectively reviewed. The influence of the parameters ‘sex’ and ‘age’ was determined. ResultsWhereas 71% of the patients had at least one MFL, 22% had an anterior MFL (aMFL), 53% had a posterior MFL (pMFL) and five percent had coexisting ligaments. The pMFLs were more likely to be present in female patients (P<0.05) but if so, they were longer in the males (P<0.05). The pMFL was categorized according to its insertion on the medial femoral condyle. Conclusions3-T MRI enables an excellent illustration of the anatomic variations of pMFLs. By modifying an anatomic classification for radiological use we measured lengths and widths of the MFLs without any difficulties. Despite its increased resolution, 3-T MRI lends no diagnostic benefit in visualizing the course of the aMFL or filigree coexisting ligaments as compared to MRI at lower field strengths.

The Sacral X Axes: Location, Structure, Movement, Parallel Kinetic Ligamentous Loading, Function, Biotensegrity Technology and Pathology. The Essential Pieces of the Low Back Pain Puzzle.

In the last century much research was accomplished on the pelvis yet the pelvis remains an enigma. Movement was located and measured, but not specified, comprehended or described. An oblique axis was suspected but not identified. Some function of the pelvis is suspected, but it has not been described or understood. Many practitioners suspect the pelvis to be the source of common low back pain, but just as many practitioners believe this not to be true. Ten years ago two separate points were located that looked like they could function as bony transverse sacral X axes providing the pelvis was symmetrical, however, if and when the pelvis is asymmetrical each point could also function with a related pelvic point and act as an oblique axis. The resting pelvis is unmoving and almost immobile, however, the erect and loaded pelvis is dynamic and filled with kinetic energy. Primary sacral loading is on the posterior interosseous ligaments and serve to suspend the sacrum. The primary loading initiates a secondary loading on the sacrotuberous ligaments that balances the primary loading. These two sets of balanced ligaments create two sets of interactive force couples and a trigger for biotensegrity. During normal gait an initial unilateral posterior innominate rotation on the side of the first step causes the ilial tuberosity to push caudad directly on the lateral sacrum causing a lateral sacral flexion with rotation. The trunk is caused to counter rotate thus decreasing loading forces to the femoral head. When loading is shifted to the contra lateral side on the second step the weight shift takes place with biotensegrity mechanics. Movement is through balanced, interchangeable, parallel, kinetically loaded ligaments that create interactive force couples. None of this was possible to determine without the sacral x axes. This is all way beyond conventional biomechanics. Acute and chronic back pain is essentially all caused from an anterior innominate rotation (lifting, bending lowering, shoveling, sweeping, pregnancy or a postural forward head) that causes the innominates to rotate cephalad and laterally at the PIIS. This is a measurable movement that puts a vertical shear on the lateral axis points and separates the sacral origins of both the gluteus maximus and the piriformis from their ilial origins resulting pain in the buttocks, piriformis syndrome and sciatica. Dysfunction is all initiated at the sacral x axes. This is corrected effectively simply with a manual bilateral posterior innominate rotation that reverses all symptoms leaving the patient free of pain.

3D Mimicry of Native-Tissue-Fiber Architecture Guides Tendon-Derived Cells and Adipose Stem Cells into Artificial Tendon Constructs.

Tendon and ligament (T/L) function is intrinsically related with their unique hierarchically and anisotropically organized extracellular matrix. Their natural healing capacity is, however, limited. Here, continuous and aligned electrospun nanofiber threads (CANT) based on synthetic/natural polymer blends mechanically reinforced with cellulose nanocrystals are produced to replicate the nanoscale collagen fibrils grouped into microscale collagen fibers that compose the native T/L. CANT are then incrementally assembled into 3D hierarchical scaffolds, resulting in woven constructions, which simultaneously mimic T/L nano-to-macro architecture, nanotopography, and nonlinear biomechanical behavior. Biological performance is assessed using human-tendon-derived cells (hTDCs) and human adipose stem cells (hASCs). Scaffolds nanotopography and microstructure induce a high cytoskeleton elongation and anisotropic organization typical of tendon tissues. Moreover, the expression of tendon-related markers (Collagen types I and III, Tenascin-C, and Scleraxis) by both cell types, and the similarities observed on their expression patterns over time suggest that the developed scaffolds not only prevent the phenotypic drift of hTDCs, but also trigger tenogenic differentiation of hASCs. Overall, these results demonstrate a feasible approach for the scalable production of 3D hierarchical scaffolds that exhibit key structural and biomechanical properties, which can be advantageously explored in acellular and cellular T/L TE strategies.

A Single-Tunnel Technique for Coracoclavicular and Acromioclavicular Ligament Reconstruction

Acromioclavicular (AC) joint separation is a common injury seen in the young adult athletic population. Both the indications for surgical management and the best operative technique remain controversial. One of the most popular reconstruction techniques is the anatomic double-tunnel coracoclavicular (CC) ligament reconstruction. However, there have been several case reports of clavicle fractures with this technique. This article presents a single-tunnel reconstruction technique that aims to restore both the CC and AC ligament function, while minimizing fracture risk.

Variations in Anterior Cruciate Ligament Anatomy

The aim of anterior cruciate ligament (ACL) reconstruction is to restore native ligament anatomy to potentially restore function. Morphologic measurements of the native ACL are a valuable asset to effective surgical planning, influencing decisions such as graft choice and single- vs double-bundle reconstruction. Several studies support the existence of high interindividual morphologic variabilities, an important factor that should be taken into account for each patient to ensure native ligament anatomy restoration and function. Anatomical features that can be objectively evaluated before and during ACL reconstruction surgery include the ACL length, tibial and femoral insertion site sizes, inclination angle, and intercondylar notch size.

Three-dimensional dynamic motion analysis of the first carpometacarpal ligaments.

The purpose of this study was to analyze the dynamic motion of the first carpometacarpal (CMC) ligaments on a three-dimensional (3-D) surface model and to examine the changes in the ligament lengths during the motion of the first CMC joint. Six fresh-frozen cadaver wrists were used to analyze the motion of the first CMC ligaments on a 3-D coordinate system using a digitizer. Four ligaments, namely, dorsoradial ligament (DRL), posterior oblique ligament (POL), superficial anterior oblique ligament (SAOL), and deep anterior oblique ligament (dAOL), were dissected and identified. Their attachments were digitized and represented on 3-D bone images. The distances between the ligament attachments of the first metacarpal and the trapezium, which were the ligament lengths, were measured during the extension-flexion and adduction-abduction of the first CMC joint. Both the DRL and POL lengthened during flexion of the first CMC joint, and both the SAOL and dAOL lengthened during extension. Both the DRL and SAOL lengthened during adduction, and both the POL and dAOL lengthened during abduction. The DRL alone lengthened significantly at flexion and adduction when the first CMC joint was in dorsoradial dislocation. The lengths of four ligaments changed significantly during first CMC joint motion. This study suggested that the DRL contributes substantial stability to the first CMC joint, preventing dorsoradial dislocation. This 3-D information improves the knowledge and understanding of the function of individual ligaments and their roles in the stability of the first CMC joint.

The effects on calcaneofibular ligament function of differences in the angle of the calcaneofibular ligament with respect to the long axis of the fibula: a simulation study

BackgroundIn the present study, CFLs harvested from cadavers were categorized according to the differences in the angle of the CFL with respect to the long axis of the fibula and their shape, and then three-dimensional reconstructions of the CFLs were used to simulate and examine the differences in the angles of the CFLs with respect to the long axis of the fibula and how they affect CFL function.MethodsThe study sample included 81 ft from 43 Japanese cadavers. CFLs were categorized according to their angle with respect to the long axis of the fibula and the number of fiber bundles. Five categories were subsequently established: CFL20° (angle of the CFL with respect to the long axis of the fibula from 20° to 29°); CFL30° (range 30–39°); CFL40° (range 40–49°); CFL50° (range 50–59°); and CFL2 (CLFs with two crossing fiber bundles). Three-dimensional reconstructions of a single specimen from each category were then created. These were used to simulate and calculate CFL strain during dorsiflexion (20°) and plantarflexion (30°) on the talocrural joint axis and inversion (20°) and eversion (20°) on the subtalar joint axis.ResultsIn terms of proportions for each category, CFL20° was observed in 14 ft (17.3%), with CFL30° in 22 ft (27.2%), CFL40° in 29 ft (35.8%), CFL50° in 15 ft (18.5%), and CFL2 in one foot (1.2%). Specimens in the CFL20° and CFL30° groups contracted with plantarflexion and stretched with dorsiflexion. In comparison, specimens in the CFL40°, CFL50°, and CFL2 groups stretched with plantarflexion and contracted with dorsiflexion. Specimens in the CFL20° and CFL2 groups stretched with inversion and contracted with eversion.ConclusionsCFL function changed according to the difference in the angles of the CFLs with respect to the long axis of the fibula.

The History and Future of Unlinked Total Elbow Arthroplasty.

Unlinked total elbow arthroplasty (TEA), which has no mechanical connection between the humeral and ulnar components, has theoretical advantages based on its near-normal elbow kinematics and the preservation of bone stock. Unlinked TEA is appropriate only for patients who have limited bone loss or limited deformity and good ligamentous function. This is because postoperative instability has been a major complication of unlinked prostheses. The concept and goal of unlinked TEA is to share the loading stress on the bone implant interface with the surrounding tissues. Although the loosening rate of unlinked prostheses theoretically should be lower than that of linked prostheses (which have a mechanical connection between the humeral and ulnar components), there is no clear evidence that unlinked TEAs are superior to linked TEAs in this respect. However, we believe that primary TEA should be performed using an unlinked TEA, especially for younger patients, because revision surgery for unlinked TEA results in longer prosthesis survival than revision surgery for linked TEA. Improvement of the design of unlinked prostheses and the introduction of less invasive surgical techniques are required to reduce postoperative instability.

Medial patellofemoral ligament reconstruction using a bone groove and a suture anchor at patellar: a safe and firm fixation technique and 3-year follow-up study.

BackgroundGraft fixation is critical to the restoration of the medial patella of femoral ligament function and long-term success. Numerous fixations at the patella have been described, while the complications including patellar fractures, violation of the posterior patella and delay of tendon-to-bone healing remain significant challenges. Here, we describe a safe and firm fixation at the patellar for medial patellofemoral ligament (MPFL) reconstruction and explore the safety angle of drilling the suture anchor at different morphology of the patellar. Moreover, we evaluate the results at a 3-year follow-up.MethodsCombined bone groove and suture anchor fixation at the patella was performed on 26 patients (16 females, 10 males; mean age 26.3 ± 4.7 years) diagnosed with recurrent patellar dislocation. The drilling direction of the suture anchor referred to the safety angle according to the Wiberg type classification. The safety angle was defined as the angle between the drill tunnel and a line that connected the medial and lateral margins of the patella and was established following computed tomography assessment of 117 patients who were diagnosed with patellar dislocation in our hospital according to the Wiberg type classification (I:29, II:65, III:23). X-ray, Lysholm, Kujala and Tegner scores were obtained preoperatively and at the time of final follow-up.ResultsThere were no patellar complications, including fracture and redislocation. Average congruence, patella tilt angles and lateral patella angle were significantly changed (P < 0.01). The Lysholm, Kujala and Tegner scores were significantly increased (P < 0.01). The safe angles of male and female patients according to the patellar Wiberg type classification were less than 45.32 ± 1.76 and 41.20 ± 1.33, 69.74 ± 1.38 and 63.66 ± 1.45 and 84.11 ± 1.67 and 80.26 ± 1.73, respectively.ConclusionsWe achieved encouraging results with this fixation at the patellar. When drilling from Wiberg type I to type III patellar, the suture anchor should be more vertical. When fixing the patellar of female patients, the drilling suture anchor should be more sloping.