Objectives. Ligaments which heal spontaneously have a healing process that is similar to skin wound healing. Menopause impairs skin wound healing and may likewise impair ligament healing. Our purpose in this study was to investigate the effect of surgical menopause on ligament healing in a rabbit medial collateral ligament model. Methods. Surgical menopause was induced with ovariohysterectomy surgery in adult female rabbits. Ligament injury was created by making a surgical gap in the midsubstance of the medial collateral ligament. Ligaments were allowed to heal for six or 14 weeks in the presence or absence of oestrogen before being compared with uninjured ligaments. Molecular assessment examined the messenger ribonucleic acid levels for collagens, proteoglycans, proteinases, hormone receptors, growth factors and inflammatory mediators. Mechanical assessments examined ligament laxity, total creep strain and failure stress. Results. Surgical menopause in normal medial collateral ligaments initiated molecular changes in all the categories evaluated. In early healing medial collateral ligaments, surgical menopause resulted in downregulation of specific collagens, proteinases and inflammatory mediators at 6 weeks of healing, and proteoglycans, growth factors and hormone receptors at 14 weeks of healing. Surgical menopause did not produce mechanical changes in normal or early healing medial collateral ligaments. With or without surgical menopause, healing ligaments exhibited increased total creep strain and decreased failure stress compared with uninjured ligaments. Conclusions. Surgical menopause did not affect the mechanical properties of normal or early healing medial collateral ligaments in a rabbit model. The results in this preclinical model suggest that menopause may result in no further impairment to the ligament healing process. . Cite this article: Bone Joint Res 2015;4:38–44

In-situ assessment of collateral ligaments strain could be key to improving total knee arthroplasty outcomes by improving the ability of surgeons to properly balance the knee intraoperatively. Ultrasound (US) speckle tracking methods have shown promise in their capability to measure in-situ soft tissue strain in large tendons but prior work has also highlighted the challenges that arise when attempting to translate these approaches to the in-situ assessment of collateral ligaments strain. Therefore, the aim of this project was to develop and validate an US speckle tracking method to specifically assess in-situ strains of both the MCL and LCL. We hypothesize that coefficients of determination (R. 2. ) would be above 0.90 with absolute differences below 0.50% strain for the comparison between US-based and the reference strain, with better results expected for the LCL compared with the MCL. Five cadaveric legs with total knee implants (NH019 2017-02-03) were submitted to a varus (LCL) and valgus (MCL) ramped loading (0 – 40N). Ultrasound radiofrequency (rf) data and reference surface strains data, obtained with 3D digital image correlation (DIC), were collected synchronously. Prior to processing, US data were qualitatively assessed and specimens displaying substantial imaging artefacts were discarded, leaving five LCL and three MCL specimens in the analysis. Ultrasound rf data were processed in Matlab (The MathWorks, Inc., Natick, MA) with a custom-built speckle tracking approach adapted from a method validated on larger tendons and based on normalized cross-correlation. Digital image correlation data were processed with commercial software VIC3D (Correlated Solutions, Inc., Columbia, SC). To optimize speckle tracking, several tracking parameters were tested: kernel and search window size, minimal correlation coefficient and simulated frame rate. Parameters were ranked according to three comparative measures between US- and DIC-based strains: R. 2. , mean absolute error and strains differences at 40N. Parameters with best average rank were considered as optimal. To quantify the agreement between US- and DIC-based strain of each specimen, the considered metrics were: R. 2. , mean absolute error and strain differences at 40N. The LCL showed a good agreement with a high average R. 2. (0.97), small average mean absolute difference (0.37%) and similar strains at 40N (DIC = 2.92 ± 0.10%; US = 2.99 ± 1.16%). The US-based speckle tracking method showed worse performance for the MCL with a lower average correlation (0.55). Such an effect has been observed previously and may relate to the difficulty in acquiring sufficient image quality for tracking the MCL compared to the LCL, which likely arises due to structural or mechanical differences; notably MCL is larger, thinner, more wrapped around the bone and stretches less. However, despite these challenges, the MCL tracking still showed small average mean absolute differences (0.44%) and similar strains at 40N (DIC = 1.48 ± 0.06%; US = 1.44 ± 1.89%). We conclude that the ultrasound speckle tracking method developed is ready to be used as a tool to assess in-situ strains of LCL. Concerning the MCL strain assessment, despite some promising results in terms of strain differences, further work on acquisition could be beneficial to reach similar performance

There is currently no commercially available and clinically successful treatment for scapholunate interosseous ligament rupture, the latter leading to the development of hand-wrist osteoarthritis. We have created a novel biodegradable implant which fixed the dissociated scaphoid and lunate bones and encourages regeneration of the ruptured native ligament. To determine if scaphoid and lunate kinematics in cadaveric specimens were maintained during robotic manipulation, when comparing the native wrist with intact ligament and when the implant was installed. Ten cadaveric experiments were performed with identical conditions, except for implant geometry that was personalised to the anatomy of each cadaveric specimen. Each cadaveric arm was mounted upright in a six degrees of freedom robot using k-wires drilled through the radius, ulna, and metacarpals. Infrared markers were attached to scaphoid, lunate, radius, and 3rd metacarpal. Cadaveric specimens were robotically manipulated through flexion-extension and ulnar-radial deviation by ±40° and ±30°, respectively. The cadaveric scaphoid and lunate kinematics were examined with 1) intact native ligament, 2) severed ligament, 3) and installed implant. Digital wrist models were generated from computed tomography scans and included implant geometry, orientation, and location. Motion data were filtered and aligned relative to neutral wrist in the digital models of each specimen using anatomical landmarks. Implant insertion points in the scaphoid and lunate over time were then calculated using digital models, marker data, and inverse kinematics. Root mean squared distance was compared between severed and implant configurations, relative to intact. Preliminary data from five cadaveric specimens indicate that the implant reduced distance between scaphoid and lunate compared to severed configuration for all but three trials. Preliminary results indicate our novel implant reduced scapho-lunate gap caused by ligament transection. Future analysis will reveal if the implant can achieve wrist kinematics similar to the native intact wrist

Introduction and Objective. The human body is designed to walk in an efficient way. As energy can be stored in elastic structures, it is no surprise that the strongest elastic structure of the human body, the iliofemoral ligament (IFL), is located in the lower limb. Numerous popular surgical hip interventions, however, affect the structural integrity of the hip capsule and there is a growing evidence that surgical repair of the capsule improves the surgical outcome. Though, the exact contribution of the iliofemoral ligament in energy efficient hip function remains unelucidated. Therefore, the objective of this study was to evaluate the influence of the IFL on energy efficient ambulation. Materials and Methods. In order to assess the potential passive contribution of the IFL to energy efficient ambulation, we simulated walking using the large public dataset (n=50) from Schreiber in a the AnyBody musculoskeletal modeling environment with and without the inclusion of the IFL. The work required from the psoas, iliacus, sartorius, quadriceps and gluteal muscles was evaluated in both situations. Considering the large uncertainty on ligament properties a parameter study was included. Results. A significant reduction in the active component of all hip flexors was observed when the IFL is intact. The required muscle work was found to be reduced by as much as 48% (CI: 29–62%), 61% (CI: 35–84%) and 38% (CI: 2–69%) for the psoas, iliacus, and sartorius muscle respectively. The IFL inclusion has no major effect on the required work from the quadriceps and the gluteal muscle group. The energy storage in the IFL is largest at maximal hip extension and the contribution to forward motion is the largest at the start of the swing phase. Conclusions. The iliofemoral ligament seems to be a crucial structure in energy efficient walking. The findings support need for meticulous reconstruction of the capsule ligament in case of surgical damage

This study aims to create a novel computational workflow for frontal plane laxity evaluation which combines a rigid body knee joint model with a non-linear implicit finite-element model wherein collateral ligaments are anisotropically modelled using subject-specific, experimentally calibrated Holzpfel-Gasser-Ogden (HGO) models. The framework was developed based on CT and MRI data of three cadaveric post-TKA knees. Bones were segmented from CT-scans and modelled as rigid bodies in a multibody dynamics simulation software (MSC Adams/view, MSC Software, USA). Medial collateral and lateral collateral ligaments were segmented based on MRI-scans and are modelled as finite elements using the HGO model in Abaqus (Simulia, USA). All specimens were submitted varus/valgus loading (0-10Nm) while being rigidly fixed on a testing bench to prevent knee flexion. In subsequent computer simulations of the experimental testing, rigid bodies kinematics and the associated soft-tissue force response were computed at each time step. Ligament properties were optimised using a gradient descent approach by minimising the error between the experimental and simulation-based kinematic response to the applied varus/valgus loads. For comparison, a second model was defined wherein collateral ligaments were modelled as nonlinear no-compression spring elements using the Blankevoort formulation. Models with subject-specific, experimentally calibrated HGO representations of the collateral ligaments demonstrated smaller root mean square errors in terms of kinematics (0.7900° +/− 0.4081°) than models integrating a Blankevoort representation (1.4704° +/− 0.8007°). A novel computational workflow integrating subject-specific, experimentally calibrated HGO predicted post-TKA frontal-plane knee joint laxity with clinically applicable accuracy. Generally, errors in terms of tibial rotation were higher and might be further reduced by increasing the interaction nodes between the rigid body model and the finite element software. Future work should investigate the accuracy of resulting models for simulating unseen activities of daily living

Chronic lateral ankle instability (CLAI) is treated operatively, whereas acute ligament injury is usually treated nonoperatively. Such treatments have been widely validated. Apoptosis is known to cause ligament degeneration; however, few reports have focused on the possible role of apoptosis in degeneration of ruptured lateral ankle ligaments. The aim of our study is to elucidate the apoptosis that occurs within anterior talofibular ligament (ATFL) to further validate current CLAI treatments by adducing molecular and cellular evidence. Between March 2019 and February 2021, 50 patients were prospectively enrolled in this study. Ruptured ATFL tissues were collected from 21 CLAI patients (group C) and 17 acute ankle fracture patients (group A). Apoptotic cells were counted using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Western blotting for caspases 3, 7, 8, and 9 and cytochrome c, was performed to explore intrinsic and extrinsic apoptotic pathways. Immunohistochemistry was used to detect caspases 3, 7, 8, and 9 and cytochrome c, in ligament vessel endothelial cells. More apoptotic cells were observed in group C than group A in TUNEL assay. Western blotting revealed that the apoptotic activities of group C ligaments were significantly higher than those of group A (all p < 0.001). Immunohistochemistry revealed increased expression of caspases 3, 7, 8, and 9, and cytochrome c, in group C compared to group A. The ATFL apoptotic activities of CLAI patients were significantly higher than those of acute ankle fracture patients, as revealed biochemically and histologically. Our data further validate current CLAI treatments from a molecular and cellular perspective. Efforts should be made to reverse or prevent ATFL apoptosis in CLAI patients

Being commonly missed in the clinical practice, Lisfranc injuries can lead to arthritis and long-term complications. There are controversial opinions about the contribution of the main stabilizers of the joint. Moreover, the role of the ligament that connects the medial cuneiform (MC) and the third metatarsal (MT3) is not well investigated. The aim of this study was to investigate the influence of different Lisfranc ligament injuries on CT findings under two specified loads. Sixteen fresh-frozen human cadaveric lower limbs were embedded in PMMA at mid-shaft of the tibia and placed in a weight-bearing radiolucent frame for CT scanning. All intact specimens were initially scanned under 7.5 kg and 70 kg loads in neutral foot position. A dorsal approach was then used for sequential ligaments cutting: first – the dorsal and the (Lisfranc) interosseous ligaments; second – the plantar ligament between the MC and MT3; third – the plantar Lisfranc ligament between the MC and the MT2. All feet were rescanned after each cutting step under the two loads. The average distances between MT1 and MT2 in the intact feet under 7.5 kg and 70 kg loads were 0.77 mm and 0.82 mm, whereas between MC and MT2 they were 0.61 mm and 0.80 mm, without any signs of misalignment or dorsal displacement of MT2. A slight increase in the distances MT1-MT2 (0.89 mm; 0.97 mm) and MC-MT2 (0.97 mm; 1.13 mm) was observed after the first disruption of the dorsal and the interosseous ligaments under 7.5 kg and 70 kg loads. A further increase in MT1-MT2 and MC-MT2 distances was registered after the second disruption of the ligament between MC and MT3. The largest distances MT1-MT2 (1.5 mm; 1.95 mm) and MC-MT2 (1.74 mm; 2.35 mm) were measured after the final plantar Lisfranc ligament cut under the two loads. In contrast to the previous two the previous two cuts, misalignment and dorsal displacement of 1.25 mm were seen at this final disrupted stage. The minimal pathological increase in the distances MT1-MT2 and MC-MT2 is an important indicator for ligamentous Lisfranc injury. Dorsal displacement and misalignment of the second metatarsal in the CT scans identify severe ligamentous Lisfranc injury. The plantar Lisfranc ligament between the medial cuneiform and the second metatarsal seems to be the strongest stabilizer of the Lisfranc joint. Partial lesion of the Lisfranc ligaments requires high clinical suspicion as it can be easily missed

Tendon and ligament injuries represent highly prevalent and unmet clinical challenge that may significantly benefit from tissue engineering therapeutic strategies, once optimal cell source and biomolecules regulating tendon homeostasis are properly defined. Herein, we aimed to evaluate the expression of tendon/ligament markers in two novel cell populations, namely human dental pulp stem cells (DPSCs) and periodontal ligament cells (PDLCs), in response to supplementation with TGF-β ligands relevant for tendon development and healing, as well as under standard tri-lineage differentiation conditions. DPSCs and PDLCs were isolated from sound human permanent molars removed for orthodontic reasons. Pulp tissue and periodontal ligament were minced and digested with collagenase (3mg/mL) and cells were expanded in α-MEM supplemented with 10% fetal bovine serum (basal medium). To evaluate the susceptibility of DPSCs and PDLCs to tenogenic induction, cells were seeded at density of 1000 cells/cm. 2. and cultured up to 21 days in basal medium or media supplemented with TGF-β3 (10ng/ml), or GDF-5 (50 ng/ml). Cell response was evaluated weakly by analysis of expression of tendon, bone and cartilage markers, employing real time RT-PCR and immunocytochemistry. A significant increase in collagen I and collagen III expression was observed with the culture progression in all conditions, with abundant matrix being deposited by day 14. A significant upregulation of scleraxis expression was demonstrated in response to supplementation with TGF-β3 in both cell populations, when compared to basal medium and medium with GDF-5. It was concluded that TGF-β3 may represent an effective inducer of stem cell tenogenic differentiation

Poor soft tissue balance in total knee arthroplasty (TKA) is one of the most primary causes of dissatisfaction and reduced joint longevity, which are associated with postoperative instability and early implant failure. 1. Therefore, surgical techniques, including mechanical instruments and 3-D guided navigation systems, in TKA aim to achieve optimum soft tissue balancing in the knee to improve postoperative outcome. 2. Patella-in-Place balancing (PIPB) is a novel technique which aims to restore native collateral ligament behaviour by preserving the original state without any release. Moreover, reduction of the joint laxity compensates for the loss of the visco-elastic properties of the cartilage and meniscus. Following its clinical success, we aimed to evaluate the impact of the PIPB technique on collateral ligament strain and laxity behaviour, with the hypothesis that PIPB would restore strains in the collateral ligaments. 3. . Eight fresh-frozen cadaveric legs were obtained (KU Leuven, Belgium, H019 2015-11-04) and CT images were acquired while rigid marker frames were affixed into the femur, and tibia for testing. After carefully removing the soft tissues around the knee joint, while preserving the joint capsule, ligaments, and tendons, digital extensometers (MTS, Minnesota, USA) were attached along the length of the superficial medial collateral ligament (MCL) and lateral collateral ligament (LCL). A handheld digital dynamometer (Mark-10, Copiague, USA) was used to apply an abduction or adduction moment of 10 Nm at fixed knee flexion angles of 0°, 30°, 60° and 90°. A motion capture system (Vicon Motion Systems, UK) was used to record the trajectories of the rigid marker frames while synchronized strain data was collected for MCL/LCL. All motion protocols were applied following TKA was performed using PIPB with a cruciate retaining implant (Stryker Triathlon, MI, USA). Furthermore, tibiofemoral kinematics were calculated. 4. and combined with the strain data. Postoperative tibial varus/valgus stresses and collateral ligament strains were compared to the native condition using the Wilcoxon Signed-Rank Test (p<0.05). Postoperative tibial valgus laxity was lower than the native condition for all flexion angles. Moreover, tibial valgus of TKA was significantly different than the native condition, except for 0° (p=0.32). Although, tibial varus laxity of TKA was lower than the native at all angles, significant difference was only found at 0° (p=0.03) and 90° (p=0.02). No significant differences were observed in postoperative collateral ligament strains, as compared to the native condition, for all flexion angles, except for MCL strain at 30° (p=0.02) and 60° (p=0.01). Results from this experimental study supported our hypotheses, barring MCL strain in mid-flexion, which might be associated with the implant design. Restored collateral ligament strains with reduced joint laxity, demonstrated by the PIPB technique in TKA in vitro, could potentially restore natural joint kinematics, thereby improving patient outcomes. In conclusion, to further prove the success of PIPB, further biomechanical studies are required to evaluate the success rate of PIPB technique in different implant designs

Abstract. Objectives. The scapholunate interosseous ligament (SLIL) has a unique C-shape following the arc of the scaphoid and lunate surfaces from distal dorsal around to distal volar. This ligament comprises of three subregions: dorsal, proximal and volar. The SLIL enthesis, a specialized region where this ligament attaches to the scaphoid and lunate, has not previously been studied despite its important mechanical function in the biomechanics of the wrist joint. This study therefore aims to compare the histomorphological differences between the SLIL subregions, including at their entheses. This study will examine the qualitative and quantitative differences between the three subregions, as well as between the scaphoid and lunate attachments. Methods. Twelve fresh-frozen human cadaveric wrists were dissected and the gross dimensions of each SLIL subregion measured. Subregions were then histologically processed for qualitative and quantitative morphological and compositional analyses, including quantification of enthesis calcified fibrocartilage (CF) area. Results. From the gross measurements taken, the dorsal subregion was the thickest. There were no significant differences in lengths and widths between the three subregions. Qualitatively, the dorsal and volar subregions had fibrocartilaginous entheses while the proximal subregion inserted into cortical bone via articular cartilage. Quantitatively, the dorsal subregion had significantly more CF than the volar subregion. There was no significant difference in the enthesis CF between scaphoid and lunate attachments in the three subregions. Conclusions. There are significant histomorphological differences between the SLIL subregions. The dorsal subregion has the largest amount of CF, which is consistent with the greater biomechanical force subjected to this subregion compared to the other subregions. This result confirms that the dorsal subregion is the strongest of the three subregions. The similar histomorphology of the ligament at the scaphoid and lunate entheses suggests that similar biomechanical forces are applied to both attachments. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Ligaments and tendons are vital musculoskeletal soft tissues, which are commonly injured due to overuse and trauma. Their distinct functions are well known however their unique structure and biochemical composition and how they change with disease is poorly described. The most commonly injured ligament in the dog and man is the cranial cruciate (CCL) and anterior cruciate ligament (ACL) respectively. Therefore, the structure, function and pathophysiology of disease of this ligament has been most commonly studied in both species. Canine cranial cruciate ligament rupture (CCLR) most commonly occurs following gradual ligament degeneration or disease (CCLD) followed by a non-contact injury or a minor trauma. Several studies have described marked degenerative histological changes in ligament structure prior to and following rupture which consist of loss of the collagen fascicular structure, areas of poor collagen fibril staining, a marked increase in “chondroid” type cells and mineralisation. The ECM protein profile is also altered with increased sulphated glycosaminoglycans content, increased immature collagen cross-links as well as enzymes involved in collagen remodelling. In man, similar findings have been described in the ACL with age and in osteoarthritis (OA). Previously it had been thought that ligament degeneration occurred following OA but these more recent studies suggest that ligament degeneration can lead to joint destabilisation and OA. Being able to determine early degenerative ligament changes in spontaneous clinical cohorts and the mechanisms which cause them are ideal starting points to determine targets for future therapies in the prevention of ligament degradation and rupture. Further identification of ligament cell types in terms of degenerative, responsive and regenerative (stem) types is essential to try and alter ligament cellular and extracellular matrices harnessing their therapeutic potential

Abstract. Cranial cruciate ligament (CrCL) disease/rupture causes pain and osteoarthritis (OA) in dogs. α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-2 and kainate (KA)-1 glutamate receptors (GluR) and the excitatory amino acid transporter-1 (EAAT-1) and EAAT-3 are expressed in joint tissues from OA patients and rodent arthritis models and represent potential therapeutic targets. Objectives. To evaluate glutamate signalling in canine diseased and normal CrCL and meniscus by immunohistochemistry (IHC). Methods. Surgical waste (CrCL, n=5 and medial meniscus, n=3) were obtained from canines with CrCL disease (RCVS ethics approval:2017/14/Alves) and normal analogous tissues (n=2). IHC optimization was performed for rabbit polyclonal (AMPA-2:ab52176, KA-1:ab67402, EAAT-1:ab416) and monoclonal (EAAT-3:ab124802) antibodies from Abcam. IHC was optimised over antibody dilutions from 1:100 to 1:5000 alongside equivalent IgG isotype controls (ab37415 and ab172730) and negative controls (TBS/Tween buffer without primary antibodies). IHC staining was compared in diseased and normal tissues and disclosed with 3,3’-Diaminobenzidine (DAB). Results. Specific immunostaining was observed for all primary antibodies, at concentrations between 2.0×10. −4. mg/mL to 1.0×10. −2. mg/mL, depending on the tissue and primary antibody. All GluR and transporters were expressed in the cellular membrane, in the normal and diseased CrCL and meniscus. Healthy CrCL showed a well-organized microstructure, with normal positively labelled ligamentocytes, whereas diseased CrCL microstructure was disrupted, with many positively stained fibroblastic cells in the epiligamentous region and evident neovascularization, indicative of ongoing repair. The normal and diseased meniscal tissues showed similar chondrocytes-like cells labelling and microstructure. Negative controls demonstrated no labelling. Conclusions. GluR and transporters expression is altered in canine diseased CrCLs, implicating glutamate signalling in this pathology. Since AMPA/KA GluR antagonists alleviate joint degeneration in post-traumatic OA in rodent models, they may be useful for the treatment of CrCL disease in dogs, as well as translated to other veterinary and human orthopaedic diseases

Although multifunctional delivery systems can potentially improve safety and efficacy of therapeutic protein delivery in the biological treatment of injured tissues, ability to track and manipulate protein delivery systems in vivo to ensure localization at the treatment site is still a concern. We hypothesized that incorporating superparamagnetic iron oxide (SPIO) into calcium phosphate (CaP) coated β-tricalcium phosphate (β-TCP) microparticles would allow for Magnetic Resonance Imaging (MRI) based tracking in vivo and SPIO incorporation would not impact the biological activity of proteins delivered with these microparticles. To address the efficacy and limitations in therapeutic protein delivery, a CaP coated microparticle which incorporates superparamagnetic iron oxide (SPIO-CaP-MP) was created and used in a rat knee medial collateral ligament. The system has trifunctional properties: (1) it is trackable using magnetic resonance imaging (MRI), (2) it can be manipulated with a magnetic field, (3) it can release active proteins in the injury site. SPIO-Ca-MPs were formed on β-tricalcium phosphate cores. Using MRI, SPIO-CaP-MPs were visible in T2 weighted sequences as an area of hypointesive signal. SPIO-CaP-MPs could be visualized and remained localized for at least 15 days after injection into the medial collateral ligament. Recombinant human basic fibroblast growth factor delivered with SPIO-CaP-MPs stimulated the proliferation of human dermal fibroblasts. Finally, SPIO-CaP-MPs could be localized to a bar magnet when suspended in solution. Taken together, these results suggest that SPIO-CaPMPs could be useful for protein delivery applications in the treatment of ligament injury that may benefit from externally controlled localization and MRI-based tracking

Summary Statement. This study explores the therapeutic use of MSCs to enhance ligament healing from an immuno-modulatory perspective. We report improved healing with MSC treatment, but inconsistent effects on inflammatory markers. Introduction. Mesenchymal stem cell (MSC) use continues to hold untapped potential as a therapeutic agent because: 1) MSCs have the ability to differentiate into several different connective tissues such as cartilage, bone, muscle and fat (1–3), and 2) MSCs can modulate immune and inflammatory responses that affect healing (4, 5). This paradigm shift from differentiation to immune modulation is being studied for different applications (6). Several studies suggest MSCs decrease inflammation by reducing pro-inflammatory cytokines and changing the macrophage phenotype from M1 (classically-activated) to M2 (alternatively-activated) (7–10). However, their immune-modulatory effects within a healing ligament remain unexplored. MSCs can behave differently depending on the tissue and healing environment they encounter, which leads to our interest in MSC immune-modulation in healing ligaments. Methods. Forty-four rats underwent bilateral MCL transection. Days 5 and 14 healing were examined comparing two cell doses (1×10. 6. MSCs or 4×10. 6. MSCs). At the time of surgery, fluorescently-labeled rat MSCs (passage 8–10) were injected into the right MCL, while the left MCL served as a control for normal healing. MCLs were collected at the different time points and processed with immunohistochemistry (n=12). Type 1 macrophages (M1) and type 2 macrophages (M2) were quantified spatially within the healing ligaments. Twelve rats with MSC injections underwent mechanical testing. A multiplex cytokine reader measured 10 different cytokines in the healing ligaments at days 5 and 14. Results. MSCs were detected solely in the healing region and healing region edges at Days 5 and 14 in both dose groups using fluorescence microscopy. At day 5, the higher dose of cells produced significant M2 changes throughout the ligament. There were more M2′s (p=.05) in the distal and proximal healing regions of the normal healing ligament compared to the MSC injection group. There were significant changes in both the low dose and high dose groups at day 14. Fewer M1′s were found in the ends (p=.01) and throughout the MCL (p=.04) in the low dose group. M2′s were decreased in the ends (p=.04), but only in the ligaments that received the higher dose of MSCs. Cytokine analysis showed a greater amount of pro-inflammatory cytokines in the high dose MSC group at Day 5 (IL-1β, IL-2, and Interferon-Y) compared to controls, along with increased IL-12 at Day 14. The low dose MSC injection group demonstrated increased strength with an average failure load of 26.4N compared to 20.9N in the control group (p=.03). Low dose ligaments also exhibited increased stiffness with an average of 12.2 N/mm compared to 10.0 N/mm (p=.01) in control ligaments. Discussion. MSCs improved healing when applied at an appropriate dose as shown by improved mechanical properties at day 14. Interestingly, the smaller dose of 1 million cells proved more successful than the larger dose of 4 million cells. MSCs also affected the cytokine profile and macrophage phenotype at both healing time points, but not always as expected with regard to inflammatory cells and cytokines

Background. The anatomy of the human body has been studied for centuries. Despite this, recent articles have announced the presence of a new knee ligament- the anterolateral ligament. It has been the subject of much discussion and media commentary. Previous anatomical studies indicate its presence, and describe its location, origin, course and insertion. Magnetic resonance imaging (MRI) is the best and most commonly used investigation to assess the ligamentous structure of the knee. To date, most MRI knee reports make no mention of the anterolateral ligament. The aim of this study was to assess for the presence of the anterolateral ligament using MRI, and to describe the structure if visualised. Methods. All right knee MRIs performed on a Siemens Magnetom Espree 1.5 Tesla scanner in Merlin Park Hospital over a 4 year period were retrospectively analysed. Patients born before 1970, or with reported abnormalities were excluded. The normal MRIs were then analysed by a consultant radiologist specialising in musculoskeletal imaging. Measurements on origin, insertion, course and length were noted. Results. 942 right knee MRIs were performed in the time period. 62 were classed as normal, and within the specified age range. 10 were randomly sampled. Of these the ligament was visible on all 10 MRIs, best viewed in the coronal plane. The average length (visible in 8/10) was 28.88mm +/− 5.14mm. The origin (visible in all 10) was 2.25mm +/− 0.39mm. The insertion (visible in 9/10) was 1.93mm +/− 0.424. The mid thickness was 1.87mm +/− 0.2mm. Conclusions. This study indicates that the ALL is a discrete, visible structure on MRI. This furthers the evidence of the presence of the ALL and also provides information that may be beneficial in future studies, and assessment of knee injuries. Level of evidence. 4

Background. Return to sports after anterior cruciate ligament reconstruction (ACLR) is multifactorial and rotational stability is one of the main concerns. Anterolateral ligament reconstruction (ALLR) has been recommended to enhance rotational stability. Purpose. To assess the effect of ALLR on return to sports. Study Design. Retrospective comparative cohort study;. Level of evidence: III. Methods. A total of 68 patients who underwent ACLR after acute ACL injury between 2015 and 2018 with a follow-up of at least 24 months were enrolled in the study. Patients with isolated ACLR (group ALL(-), n=41) were compared to patients with ACLR+ALLR (group ALL(+), n=27) in regard to subjective knee assessment via Tegner activity scale, Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale, Knee Documentation Committee (IKDC) form and Lysholm score. All tests were performed before the surgery, at 6 months and 24 months postoperatively. Results. Mean follow-up was 29.7±2.9 months for group ALL(-) and 31.6±3.0 for ALL(+) (p=0.587). Tegner, ACL-RSI and IKDC scores at last follow-up were significantly better in ALL(+) compared to ALL(-). There were no significant differences in isokinetic extensor strength and single-leg hop test results between the groups. 40 (97.6%) patients in ALL(-) and 27 (100%) in ALL(+) had a grade 2 or 3 pivot shift (p=0.812) preoperatively. Postoperatively, 28 (68.3%) patients in ALL(-) and 25 (92.6%) patients in ALL(+) had a negative pivot shift (p<0.001). 2 (5.9%) patients in ALL(-) and 1 (3.7%) patient in ALL(+) needed ACLR revision due to traumatic re-injury (p=0.165). There was no significant difference in the rate of return to any sports activity (87.8% in ALL(-) vs 88.9% in ALL(+); p=0.532), but ALL(+) showed a higher rate of return to the same level of sports activity (55.6%) than group ALL(-) (31.7%) (p=0.012). Conclusion. ACLR combined with ALLR provided a significantly higher rate of return to the same level sports activity than ACLR alone, probably due to enhanced rotational stability

Limited information is published regarding the activity level after gracilis autograft reconstruction, and usually a knee-injury based score is used rather than a specific ankle PROM. The purpose of this study was to investigate the activity level and functional results after lateral ankle gracilis autograft reconstruction in patients with severe lateral ankle instability. The hypothesis was that patients would regain their pre-injury Tegner activity level or one level below and secondary to compare a specific ankle activity score, instability and function score. Finally, donor site and graft complications, clinical stability and range of motion were measured. All 69 patients (50 women, 19 men) recorded at the hospital with severe instability who underwent reconstruction of the anterior talofibular and the calcaneofibular ligament with a gracilis autograft and were minimum 6 months post-operative, were invited to participate in the study. Outcomes measures included the Tegner Activity level (1–10), Ankle Activity Score (0–10) recorded as pre-injury and at follow up. The Karlsson Petterson Ankle Function Score (0–100) and Visual Analog Score (VAS)(0–10) recorded pre-operatively and at follow up. All pre-injury and pre-operative data were recalled retrospectively from memory. Identification of functional ankle instability (IDFAI)(0–37) was recorded at follow up. The clinical tests, Anterior drawer test (0–4), Talar tilt test (0–4) and Range of motion (ROM)(degrees) were compared to the unaffected side at follow up. A difference of 1 in the activity scores was chosen as a clinical relevant difference. Data was tested for normal distribution and for statistical significant difference with a students t-test. study design: Cross sectional clinical study with a retrospective questionnaire. A total of 33 patients (27 women, 6 men), with a mean age on 45 years (range 19–68), were included in this study. Mean follow up was 3.7 years. Mean pre-operative Tegner score was 5.8 vs 5.6 at follow up (p. On average, the patients returned to their pre-injury activity level, with similar specific ankle activity scores to the Tegner. The majority had good functional results and few residual symptoms of functional instability. The response rate was low with few men responding; hence a prospective study is called for to establish the true effect of the surgical technique

The anterolateral ligament (ALL) has been recently recognized as a distinct stabilizer for internal rotation in the ACL-deficient knee and it has been hypothesized that ALL reconstruction may play an important role in improving anterolateral instability following ACL reconstruction. Both the gracilis tendon (GT) and a portion of the iliotibial band (ITB) have been suggested as graft materials for ALL reconstruction, however, there is an ongoing debate concerning whether GT or ITB are appropriate grafting materials. Furthermore, there is limited knowledge in how the mechanical properties of these potential grafts compare to the native ALL. Consequently, the aim of this study was to characterize the elastic (Young's modulus and failure load) and viscoelastic (dynamic and static creep) mechanical properties of the ALL and compare these results with the characteristics of the grafting materials (GT and ITB), in order to provide guidance to clinicians with respect to graft material choice. Fourteen fresh-frozen cadaveric knees (85.2±12.2 yr) were obtained. The ALL, ITB, and the distal (GTD) and proximal gracilis tendons (GTP) (bisected at mid portion) were harvested from each donor and tested with a dynamic material testing frame. Prior to testing, the cross-sectional area of each tissue was measured using a casting method and the force required to achieve a min-max stress (1.2–12 MPa) for the testing protocol was calculated (preconditioning (20 cycles, 3–6 MPa), sinusoidal cycle (200 cycles, 1.2–12 MPa), dwell at constant load (100 s, 12 MPa), and load to failure (3%/s)). Kruskall-Wallis tests were used to compare all tissue groups (p<0.05). The Young's modulus of both ALL (181.3±63.9 MPa) and ITB (357.6±94.4 MPa) are significantly lower than GTD (835.4±146.5 MPa) and GTP (725.6±227.1 MPa). In contrast, the failure load of ALL (124.5±40.9 N) was comparable with GTD (452.7±119.3 N) and GTP (433±133.7 N), however, significantly lower than ITB (909.6±194.7 N). Dynamic creep of the ALL (0.5±0.3 mm) and ITB (0.7±0.2 mm) were similar (p>0.05) whereas the GTD (0.26±0.06 mm) and GTP (0.28±0.1 mm) were significantly lower. Static creep progression of the ALL (1.09±0.4 %) was highest across all tissues, while GTD (0.24±0.05 %) and GTP (0.25±0.0.04 %) were lowest and comparable with ITB (0.3±0.07 %) creep progression. Since grafts from the ITB, GTD and GTP were comparable to the ALL only for certain mechanical properties, there was no clear preference for using one over another for ALL reconstruction. Therefore, further studies should be performed in order to evaluate which parameters play a vital role to determine the optimum grafting choice

Introduction:. The transverse acetabular ligament (TAL) antomy is not a well explored aspect of the hip joint with limited morphological description in the reviewed literature. It is often used as an anatomical landmark for orientation of the acetabular component in total hip arthroplasty (THA). There is debate as to whether it represents an appropriate guide to cup placement in THA. Present descriptions in orthopaedic literature conside it as a single plane structure to which the surgeon can align the cup. The aim of the current study was to investigate the morphology of the TAL and it was hypothesised that the current description of it being a plane would prove insufficient. Materials and methods:. Seven dry bone hemi-pelves were reconstructed using a microscribe and rhinoceros 4.0 3D software to visualise attachment sites. Three hips from two female donors were dissected to expose the acetabulum and the TAL. This structure was removed and a footprint taken of its perimeter and attachment sites for measurement of ligament length, breadth and area of attachment from digital photographs. Finally, 3D models of the dissected acetabuli with an outline of the TAL and attachment sites were created as before. Results:. The TAL extended beyond the acetabular notch, around the circumference of the acetabular rim. Two attachment sites were identified in each specimen, found at two sites in the superior half of the acetabular rim; one anterior and one posterior. In one specimen, an additional attachment site was identified on the posterior horn. TAL length in each specimen as measured from 2D digital photographs were 132 mm, 117 mm and 179 mm, with attachment areas of 215 mm. 2. , 150 mm. 2. and 350 mm. 2. , respectively. There was marked variation in ligament breadth both between and within individual specimens, ranging from 2.6 to 5.3mm in the smallest specimen and 3.2 to 6.3mm in the largest specimen. The whole structure as one does not conform to be a plane of orientation. Discussion:. Contrary to previous literature assumption, the TAL extended far beyond the acetabular notch. Likewise, its attachment sites were found further round the acetabular rim than previously described. The unexpected breadth may explain the disagreement between studies looking at the structure as an anatomical plane. Further biomechanical research may determine which part – if any – of the ligament, should the acetabular component be orientated to. The details will be presented in the paper

Introduction. Tendons and ligaments (TLs) play key roles in the musculoskeletal system. However, they are commonly damaged due to age-related wear and tear or torn in traumatic/sport related incidents resulting in pain and immobility. TLs contain cells and extracellular matrix (ECM) comprised of collagen, elastin, glycoproteins and proteoglycans. Although TLs are composed of similar components, their precise composition and arrangement of matrix macromolecules differ to provide specific mechanical properties and functions. To date little is known about how the main ECM proteins are arranged between the two tissue types. This data will provide essential information on fundamental structure of TLs leading to increased understanding of the function relationship between these tissue types. The aim of this study was to compare tendon-ligament differences in their ECM distribution of collagens, proteoglycans and elastic fibres. Materials and Methods. Anterior cruciate ligament (ACL) and long digital extensor tendon (LDET) were harvested from disease free cadaveric canine knee joints (n=3). Distributions of the main ECM components were assessed on longitudinal sections of ACL and LDET mid-substance. Antibody staining were assessed for collagen type I, III, VI, agreccan, versican, decorin, biglycan, elastin, fibrillin 1 and fibrillin 2. Results. Marked staining of collagen type I was present at fascicular regions, but also present at the interfascicular matrix (IFM). Collagen type III was present at the IFM of tendon, whilst in the ligament it was more widespread being located at both fascicles and IFM. In both TLs, collagen type VI was localised at IFM, but also present surrounding TL fibroblasts. A marked staining of aggrecan and versican was observed in ligament IFM, with pericellular staining of aggrecan present only in ligament. Decorin was found in both fascicular and IFM, whilst biglycan was occasionally present pericelullarly and at IFM in tendon. A similar pattern of elastic fibre distribution was found in both TLs. Discussion. This study has revealed a different ECM distribution of collagen type III, aggrecan, versican in ligament than when compared to tendon. These finding may relate to different functions between TLs and indicate that ligament is subjected to more compressive forces, resulting in different macromolecular arrangements that protect the tissue from damage