The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting

The structure and function of the anterolateral complex (ALC) of the knee has created much controversy since the 're-discovery' of the anterolateral ligament (ALL) and its proposed role in aiding control of anterolateral rotatory laxity in the anterior cruciate ligament (ACL) injured knee. A group of surgeons and researchers prominent in the field gathered to produce consensus as to the anatomy and biomechanical properties of the ALC. The evidence for and against utilisation of ALC reconstruction was also discussed, generating a number of consensus statements by following a modified Delphi process. Key points include that the ALC consists of the superficial and deep aspects of the iliotibial tract with its Kaplan fibre attachments on the distal femur, along with the ALL, a capsular structure within the anterolateral capsule. A number of structures attach to the area of the Segond fracture including the capsule-osseous layer of the iliotibial band, the ALL and the anterior arm of the short head of biceps, and hence it is not clear which is responsible for this lesion. The ALC functions to provide anterolateral rotatory stability as a secondary stabiliser to the ACL. Whilst biomechanical studies have shown that these structures play an important role in controlling stability at the time of ACL reconstruction, the optimal surgical procedure has not yet been defined clinically. Concern remains that these procedures may cause constraint of motion, yet no clinical studies have demonstrated an increased risk of osteoarthritis development. Furthermore, clinical evidence is currently lacking to support clear indications for lateral extra-articular procedures as an augmentation to ACL reconstruction. The resulting statements and scientific rationale aim to inform readers on the most current thinking and identify areas of needed basic science and clinical research to help improve patient outcomes following ACL injury and subsequent reconstruction. Level of evidence V

A Finite Element Analysis of the Effects of Lateral Meniscus Posterior Root Avulsions on Tibiofemoral Contact Mechanics

Purpose: The effects of lateral meniscus posterior root avulsions have been studied in combination with meniscofemoral ligament (MFL) deficiencies. This submission updates progress from a poster presentation at last year’s WMed Research day with preliminary results done to validate a set of biomechanical finite element analyses (FEA) against previously reported experimental results done on cadaveric knees. Methods: A finite element model which examines intact and deficient knees with the following conditions will be presented: (1) intact, (2) lateral posterior root avulsion, (3) deficient MFLs and lateral meniscus posterior root avulsion. The model of each condition will maintain a fixed flection angle of 0° under a 1000 N compressive load. The model outputs include contact area and pressure in the tibiofemoral contact region. Results: A preliminary set of FEA computations will be presented providing contact area and pressure distribution across the tibiofemoral contact region. This will include discussion of early development work including MRI segmentation and mesh creation using 3D slicer and HyperMesh software packages as well as model setup and parameters used to run the analysis in Abaqus finite element solver. Conclusion: Development of musculoskeletal finite element models, especially those validated against laboratory experimentation, are critical to describe the biomechanics of dynamic axial loads, rotational loads, and shear stress incident upon the knee. The preliminary results will help provide progress to further work in order to validate the set of models to describe the contact mechanics of intact and structurally deficient knee joints. The clinical relevance includes providing orthopaedic surgeons will an improved knowledge of the biomechanical consequences of the available repair techniques, and thus improved capability for surgical decision making. This research project would like to present this work in an oral, podium format

Experimental Characterization and Numerical Simulations of Surgical Knots

INTRODUCTION: Suture strength and knot topology are two of the several factors impacting the strength of surgical repairs in soft tissue such as a tendon and skin. The measurement and comparison of the strength of knotted suture is complicated by the lack of consensus test methods. Several prior studies assess FiberWire and others sutures, however, they evaluate or compare only the gross structural response of specific sutures or their knots without direct investigation of the governing mechanics. Little has been reported about the constituents of the suture, the core and jacket separately, nor their impact on the knot strength and failure mechanisms. PURPOSE: To develop a 3D finite element model of a surgical knot in order to determine the influence of knot topology and other factors governing the mechanics of surgical suture. MATERIAL & METHODS: An experimental study No.2 FiberWire was performed to observe the governing mechanics and to obtain data for finite element model validation. FiberWire suture is composed of a core covered with a jacket; each was tested separately and together as manufactured. A finite element model was created consisting of one knot throw. RESULTS: The maximum load of the core and jacket are approximately 65 N and 210 N respectively, and the maximum strain is 2.6% for the core and 9% for the jacket. The as-manufactured suture exhibited a failure mechanism akin to a child’s “finger trap” toy, that is, the core failed several times prior to complete failure of the suture. The finite element results were consistent with the experiments. They explain that the knot’s ~50% strength reduction relative to suture is due to the stresses from bending, twisting, and the stress concentrations from knot frictional contact. CONCLUSIONS: Under tension, the braided jacket lengthens and narrows while the angle between the warp and weft threads changes. Therefore, the circumference shrinks with increases in tension and “traps” the core with compression. This permits shear load transferred between the core and the jacket after core failure. The finite element of the knot is qualitatively consistent with experimental results. Thus, the model can be used in additional investigations

Comprehensive Clinical Evaluation of Femoroacetabular Impingement: Part 3, Magnetic Resonance Imaging

Radiologic imaging is an essential supplement to the physical examination in the evaluation of a patient with femoroacetabular impingement. Plain radiographs are the initial modality of choice for the evaluation of bony anatomy and pathology. Magnetic resonance imaging supplements the physical examination and standard radiographs by enabling qualitative and quantitative evaluation of both articular cartilage and soft tissues about the hip. Magnetic resonance imaging also provides improved 3-dimensional characterization of the bony anatomy owing to the multiplanar nature of this technique. This article describes a comprehensive approach to interpretation of magnetic resonance examination of the hip

Comprehensive Clinical Evaluation of Femoroacetabular Impingement: Part 2, Plain Radiography

The use of hip arthroscopy to treat various forms of hip pathology continues to grow. As part of a standard evaluation for eligibility for hip arthroscopy, we routinely obtain standard radiographs to assess the hip joint. These include orthogonal projections of the acetabulum and proximal femur, which can be obtained with a standing false profile, supine anteroposterior pelvis, and a lateral view of the proximal femur (either Dunn 45° or 90°, frog-leg lateral, or cross-table lateral). A comprehensive analysis of the radiographs is of utmost importance in order to indicate a patient for hip arthroscopy, for preoperative planning, and to determine prognosis. The purpose of this Technical Note is to provide a comprehensive guide of how our group performs qualitative and quantitative analysis of hip radiographs in a potential candidate for hip arthroscopy

Bone Marrow Aspirate Concentrate Harvesting and Processing Technique

Bone marrow obtained by iliac crest aspiration is a common source for harvesting mesenchymal stem cells, other progenitor cells, and associated cytokine/growth factors. Recent studies have reported good to excellent outcomes with the use of bone marrow aspirate concentrate (BMAC) for pain relief in the treatment of focal chondral lesions and osteoarthritis of the knee. However, the harvesting and processing technique are crucial to achieve satisfactory results. Several studies have examined outcomes after BMAC injection, with encouraging results, but there is a lack of consensus in terms of the frequency of injection, the amount of BMAC that is injected, and the timing of BMAC injections. The purpose of this Technical Note was to describe a standardized bone marrow aspiration harvesting technique and processing method

Comprehensive Clinical Evaluation of Femoroacetabular Impingement: Part 1, Physical Examination

A thorough evaluation of the hip must include a comprehensive medical and surgical history focused on the hip joint, surrounding soft tissues, and the associated structures of the spine, pelvis, and lower extremities. These details can guide the physical examination and provide insight into the cause of the patient's chief complaints. A proper examination includes physical examination while the patient is in the upright, supine, prone, and lateral position, as well as an evaluation of gait. Guided by a thorough history, the physical examination enables the surgeon to distinguish between intra-articular and extra-articular contributors to hip pain, selection of appropriate imaging modalities, and ultimately supports medical decision making

Meniscal Repair With Fibrin Clot Augmentation

Meniscal injuries and meniscal loss are associated with changes in knee kinematics and loading, ultimately leading to poor functional outcomes and increased risk of progression to osteoarthritis. Biomechanical studies have shown restored knee function, and clinical studies have reported improved outcomes and decreased risk of osteoarthritis after meniscal repair. This has led orthopaedic surgeons to try and save the meniscus by repair whenever possible, as shown by increasing incidence of meniscal repair surgeries. Historically, meniscal lesions, particularly those greater in size and located in the white-white region of the meniscus, have been shown to have poor healing. In recent years, there has been an increasing interest in the use of biologic agents to help stimulate and expedite healing in traditionally more avascular tissue. Preliminary results for biologic therapeutic agents, such as platelet rich plasma and bone marrow aspirate concentrate, have been encouraging. However, these options are more demanding in regard to time, financial burden, resources, and regulations than some more classic agents such as fibrin clots. Fibrin clot is readily available, easy to use, affordable, and minimally invasive. This Technical Note describes a step-by-step and reproducible technique for harvesting, preparation, and using a fibrin clot to augment healing of meniscal repairs

Anterolateral Knee Extra-articular Stabilizers: A Robotic Sectioning Study of the Anterolateral Ligament and Distal Iliotibial Band Kaplan Fibers

© 2018, © 2018 The Author(s). Background: The individual kinematic roles of the anterolateral ligament (ALL) and the distal iliotibial band Kaplan fibers in the setting of anterior cruciate ligament (ACL) deficiency require further clarification. This will improve understanding of their potential contribution to residual anterolateral rotational laxity after ACL reconstruction and may influence selection of an anterolateral extra-articular reconstruction technique, which is currently a matter of debate. Hypothesis/Purpose: To compare the role of the ALL and the Kaplan fibers in stabilizing the knee against tibial internal rotation, anterior tibial translation, and the pivot shift in ACL-deficient knees. We hypothesized that the Kaplan fibers would provide greater tibial internal rotation restraint than the ALL in ACL-deficient knees and that both structures would provide restraint against internal rotation during a simulated pivot-shift test. Study Design: Controlled laboratory study. Methods: Ten paired fresh-frozen cadaveric knees (n = 20) were used to investigate the effect of sectioning the ALL and the Kaplan fibers in ACL-deficient knees with a 6 degrees of freedom robotic testing system. After ACL sectioning, sectioning was randomly performed for the ALL and the Kaplan fibers. An established robotic testing protocol was utilized to assess knee kinematics when the specimens were subjected to a 5-N·m internal rotation torque (0°-90° at 15° increments), a simulated pivot shift with 10-N·m valgus and 5-N·m internal rotation torque (15° and 30°), and an 88-N anterior tibial load (30° and 90°). Results: Sectioning of the ACL led to significantly increased tibial internal rotation (from 0° to 90°) and anterior tibial translation (30° and 90°) as compared with the intact state. Significantly increased internal rotation occurred with further sectioning of the ALL (15°-90°) and Kaplan fibers (15°, 60°-90°). At higher flexion angles (60°-90°), sectioning the Kaplan fibers led to significantly greater internal rotation when compared with ALL sectioning. On simulated pivot-shift testing, ALL sectioning led to significantly increased internal rotation and anterior translation at 15° and 30°; sectioning of the Kaplan fibers led to significantly increased tibial internal rotation at 15° and 30° and anterior translation at 15°. No significant difference was found when anterior tibial translation was compared between the ACL/ALL- and ACL/Kaplan fiber–deficient states on simulated pivot-shift testing or isolated anterior tibial load. Conclusion: The ALL and Kaplan fibers restrain internal rotation in the ACL-deficient knee. Sectioning the Kaplan fibers led to greater tibial internal rotation at higher flexion angles (60°-90°) as compared with ALL sectioning. Additionally, the ALL and Kaplan fibers contribute to restraint of the pivot shift and anterior tibial translation in the ACL-deficient knee. Clinical Relevance: This study reports that the ALL and distal iliotibial band Kaplan fibers restrain anterior tibial translation, internal rotation, and pivot shift in the ACL-deficient knee. Furthermore, sectioning the Kaplan fibers led to significantly greater tibial internal rotation when compared with ALL sectioning at high flexion angles. These results demonstrate increased rotational knee laxity with combined ACL and anterolateral extra-articular knee injuries and may allow surgeons to optimize the care of patients with this injury pattern