In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.
Arthroscopy is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the joint through a small incision. Arthroscopic procedures can be performed during ACL reconstruction.
Anterior cruciate ligament reconstruction is a surgical tissue graft replacement of the anterior cruciate ligament, located in the knee, to restore its function after an injury. The torn ligament can either be removed from the knee, or preserved before reconstruction through an arthroscopic procedure. ACL repair is also a surgical option. This involves repairing the ACL by re-attaching it, instead of performing a reconstruction. Theoretical advantages of repair include faster recovery and a lack of donor site morbidity, but randomised controlled trials and long-term data regarding re-rupture rates using contemporary surgical techniques are lacking.
A meniscus is a crescent-shaped fibrocartilaginous anatomical structure that, in contrast to an articular disc, only partly divides a joint cavity. In humans they are present in the knee, wrist, acromioclavicular, sternoclavicular, and temporomandibular joints; in other animals they may be present in other joints.
A meniscus transplant or meniscal transplant is a transplant of the meniscus of the knee, which separates the thigh bone (femur) from the lower leg bone (tibia). The worn or damaged meniscus is removed and is replaced with a new one from a donor. The meniscus to be transplanted is taken from a cadaver, and, as such, is known as an allograft. Meniscal transplantation is technically difficult, as it must be sized accurately for each person, positioned properly and secured to the tibial plateau. As of 2012, only a few surgeons have significant volume of experience in meniscus transplantation worldwide.
Articular cartilage, most notably that which is found in the knee joint, is generally characterized by very low friction, high wear resistance, and poor regenerative qualities. It is responsible for much of the compressive resistance and load bearing qualities of the knee joint and, without it, walking is painful to impossible. Osteoarthritis is a common condition of cartilage failure that can lead to limited range of motion, bone damage and invariably, pain. Due to a combination of acute stress and chronic fatigue, osteoarthritis directly manifests itself in a wearing away of the articular surface and, in extreme cases, bone can be exposed in the joint. Some additional examples of cartilage failure mechanisms include cellular matrix linkage rupture, chondrocyte protein synthesis inhibition, and chondrocyte apoptosis. There are several different repair options available for cartilage damage or failure.
Meniscal cartilage replacement therapy is surgical replacement of the meniscus of the knee as a treatment for where the meniscus is so damaged that it would otherwise need to be removed.
The unhappy triad, also known as a blown knee among other names, is an injury to the anterior cruciate ligament, medial collateral ligament, and meniscus. Analysis during the 1990s indicated that this 'classic' O'Donoghue triad is actually an unusual clinical entity among athletes with knee injuries. Some authors mistakenly believe that in this type of injury, "combined anterior cruciate and medial collateral ligament disruptions that were incurred during athletic endeavors" always present with concomitant medial meniscus injury. However, the 1990 analysis showed that lateral meniscus tears are more common than medial meniscus tears in conjunction with sprains of the ACL.
Microfracture surgery is an articular cartilage repair surgical technique that works by creating tiny fractures in the underlying bone. This causes new cartilage to develop from a so-called super-clot.
A tear of a meniscus is a rupturing of one or more of the fibrocartilage strips in the knee called menisci. When doctors and patients refer to "torn cartilage" in the knee, they actually may be referring to an injury to a meniscus at the top of one of the tibiae. Menisci can be torn during innocuous activities such as walking or squatting. They can also be torn by traumatic force encountered in sports or other forms of physical exertion. The traumatic action is most often a twisting movement at the knee while the leg is bent. In older adults, the meniscus can be damaged following prolonged 'wear and tear'. Especially acute injuries can lead to displaced tears which can cause mechanical symptoms such as clicking, catching, or locking during motion of the joint. The joint will be in pain when in use, but when there is no load, the pain goes away.
Articular cartilage repair treatment involves the repair of the surface of an articular joint's hyaline cartilage. Over the last few decades, surgeons and researchers have made progress in elaborating surgical cartilage repair interventions. Though these solutions do not perfectly restore the articular cartilage, some of the latest technologies have started to bring very promising results in repairing cartilages from traumatic injuries or chondropathies. These treatments have been shown to be especially beneficial for patients who have articular cartilage damage. They can provide some measure of pain relief, while at the same time slowing down the accumulation of damage, or considerably delaying the need for joint replacement surgery.
Articular cartilage damage in the knee may be found on its own but it will more often be found in conjunction with injuries to ligaments and menisci. People with previous surgical interventions face more chances of articular cartilage damage due to altered mechanics of the joint. Articular cartilage damage may also be found in the shoulder causing pain, discomfort and limited movement. Cartilage structures and functions can be damaged. Such damage can result from a variety of causes, such as a bad fall or traumatic sport-accident, previous knee injuries or wear and tear over time. Immobilization for long periods can also result in cartilage damage.
Autologous chondrocyte implantation is a biomedical treatment that repairs damages in articular cartilage. ACI provides pain relief while at the same time slowing down the progression or considerably delaying partial or total joint replacement surgery. The goal of ACI is to allow people suffering from articular cartilage damage to return to their old lifestyle; regaining mobility, going back to work and even practicing sports again.
Mesenchymal stem cells (MSCs) are multipotent cells found in multiple human adult tissues including bone marrow, synovial tissues, and adipose tissues. Since they are derived from the mesoderm, they have been shown to differentiate into bone, cartilage, muscle, and adipose tissue. MSCs from embryonic sources have shown promise scientifically while creating significant controversy. As a result, many researchers have focused on adult stem cells, or stem cells isolated from adult humans that can be transplanted into damaged tissue.
The Stone Clinic is a sports medicine clinic in San Francisco, California, offering orthopaedic surgery and medical care, physical therapy and rehabilitation, and radiology imaging services. The Stone Clinic was founded by Kevin R. Stone, M.D., an orthopaedic surgeon, combining himself with a team of nurses, physical therapists, imaging specialists, and patient coordinators, in 1988 to focus on caring for injured athletes and people experiencing arthritis pain.
Cartilage repair techniques are the current focus of large amounts of research. Many different strategies have been proposed as solutions for cartilage defects. Surgical techniques currently being studied include:
Gene therapy for osteoarthritis is the application of gene therapy to treat osteoarthritis (OA). Unlike pharmacological treatments which are administered locally or systemically as a series of interventions, gene therapy aims to establish sustained therapeutic effect after a single, local injection.
High tibial osteotomy is an orthopaedic surgical procedure which aims to correct a varus deformation with compartmental osteoarthritis. Since the inception of the procedure, advancements to technique, fixation devices, and a better understanding of patient selection has allowed HTO to become more popular in younger, more active patients hoping to combat arthritis. The idea behind the procedure is to realign the weight-bearing line of the knee. By realigning the knee, the force produced from weight-bearing is shifted from the arthritic, medial compartment to the healthy, lateral compartment. This decrease in force or load in the diseased part of the knee joint decreases knee pain and can delay the development or progression of osteoarthritis in the medial compartment.
Artificial cartilage is a synthetic material made of hydrogels or polymers that aims to mimic the functional properties of natural cartilage in the human body. Tissue engineering principles are used in order to create a non-degradable and biocompatible material that can replace cartilage. While creating a useful synthetic cartilage material, certain challenges need to be overcome. First, cartilage is an avascular structure in the body and therefore does not repair itself. This creates issues in regeneration of the tissue. Synthetic cartilage also needs to be stably attached to its underlying surface i.e. the bone. Lastly, in the case of creating synthetic cartilage to be used in joint spaces, high mechanical strength under compression needs to be an intrinsic property of the material.
Artificial ligaments are devices used to replace damaged ligaments. Today, the most common use of artificial ligaments is in anterior cruciate ligament reconstruction. Although autotransplantation remains the most common method of ligament reconstruction, numerous materials and structures were developed to optimize the artificial ligament since its creation in the World War I era. Many modern artificial ligaments are made of synthetic polymers, such as polyethylene terephthalate. Various coatings have been added to improve the biocompatibility of the synthetic polymers. Early artificial ligaments developed in the 1980s were ineffective due to material deterioration. Currently, the Ligament Advanced Reinforcement System (LARS) artificial ligament has been utilized extensively in clinical applications. Tissue engineering is a growing area of research which aims to regenerate and restore ligament function.
