The Knee Flashcards
Describe the screw home mechanism
Find out:
Extension:
• The femur glides anteriorly on tibia.
• Last 20o of extension, anterior glide persists on the tibia’s medial condyle.
• This anterior glide produces external tibial rotation.
Flexion:
• Initiation of flexion occurs with posterior glide on the longer medial condyle.
• Between 0-20o flexion, posterior glide on the medial side reverses the screw-home mechanism, unlocking the knee through internal tibial rotation.
What is discoid meniscus?
A discoid meniscus is thicker than normal, and often oval or disc-shaped. It is more prone to injury than a normally shaped meniscus.
Most common on the lateral meniscus.
What are the types of discoid meniscus?
There are three types of discoid menisci:
• Incomplete. The meniscus is slightly thicker and wider than normal.
• Complete. The meniscus completely covers the tibia.
• Hypermobile Wrisberg. This occurs when the ligaments that attach the meniscus to the femur and tibia are absent. Without these ligaments, even a fairly normally shaped meniscus can sometimes slip into the joint and cause pain, as well as locking and popping of the knee.
What causes discoid meniscus?
The cause of discoid meniscus is not known. It is a congenital (present at birth) defect.
Injuries to the discoid meniscus often occur with twisting motions to the knee, such as during sports that require pivoting or fast changes in direction.
Why are discoid meniscus more prone to injuries?
A discoid meniscus is more prone to injury than a normal meniscus. The thick, abnormal shape of a discoid meniscus makes it more likely to get stuck in the knee or tear. If the meniscofemoral ligament attachment to the femur is also missing, the risk for injury is even greater.
Once injured, even a normal meniscus is difficult to heal. This is because the meniscus lacks a strong blood supply and the nutrients that are essential to healing cannot reach the injured tissues.
In many cases of discoid meniscus, patients experience symptoms without there being any injury to the meniscus.
What is the treatment for discoid meniscus?
Surgical Procedure. Treatment will depend upon the type of discoid meniscus.
Complete and incomplete discoid menisci with no tears are typically treated with saucerization, a procedure in which the meniscus is cut and re-shaped into a crescent.
If the discoid meniscus is also torn, the surgeon may perform a saucerization and then trim away the torn portion. Some tears can be repaired with stitches, rather than removed.
The hypermobile Wrisberg form of discoid meniscus is saucerized if necessary, then stabilized with stitches to sew the meniscus to the lining of the joint.
What is Osgoods Schlaters Disease?
Sindig Larsen Johannsen syndrome
Osgood-Schlatter disease is a condition that causes pain and swelling below the knee joint, where the patellar tendon attaches to the top of the shinbone (tibia), a spot called the tibial tuberosity. There may also be inflammation of the patellar tendon, which stretches over the kneecap.
Inflammation of the tibial tuberosity where the patella tendon inserts -> tibial tubercle
Sindig Larsen Johannsen syndrome -> proximal pole of patella
What causes Osgoods Schlaters Disease?
Osgood-Schlatter disease is caused by irritation of the bone growth plate. Bones do not grow in the middle, but at the ends near the joint, in an area called the growth plate. While a child is still growing, these areas of growth are made of cartilage instead of bone. The cartilage is never as strong as the bone, so high levels of stress can cause the growth plate to begin to hurt and swell.
X-ray of the knees, identifying the location of the growth plates
The tendon from the kneecap (patella) attaches down to the growth plate in the front of the leg bone (tibia). The thigh muscles (quadriceps) attach to the patella, and when they pull on the patella, this puts tension on the patellar tendon. The patellar tendon then pulls on the tibia, in the area of the growth plate. Any movements that cause repeated extension of the leg can lead to tenderness at the point where the patellar tendon attaches to the top of the tibia. Activities that put stress on the knee—especially squatting, bending or running uphill (or stadium steps)—cause the tissue around the growth plate to hurt and swell. It also hurts to hit or bump the tender area. Kneeling can be very painful.
What are the symptoms of osgood schlatter disease?
Painful symptoms are often brought on by running, jumping, and other sports-related activities. In some cases, both knees have symptoms, although one knee may be worse than the other.
Knee pain and tenderness at the tibial tubercle
Swelling at the tibial tubercle
Tight muscles in the front or back of the thigh
This will include applying pressure to the tibial tubercle, which should be tender or painful for a child with Osgood-Schlatter disease
What is the treatment for osgood schlatter disease?
In almost every case, surgery is not needed. This is because the cartilage growth plate eventually stops its growth and fills in with bone when the child stops growing. The bone is stronger than cartilage and less prone to irritation. The pain and swelling go away because there is no new growth plate to be injured. Pain linked to Osgood-Schlatter disease almost always ends when an adolescent stops growing.
In rare cases, the pain persists after the bones have stopped growing. Surgery is recommended only if there are bone fragments that did not heal. Surgery is never done on a growing athlete, since the growth plate can be damaged.
Treatment for Osgood-Schlatter disease focuses on reducing pain and swelling. This typically requires limiting exercise activity until your child can enjoy activity without discomfort or significant pain afterwards. In some cases, rest from activity is required for several months, followed by a strength conditioning program. However, if your child does not have a large amount of pain or a limp, it may be safe for them to continue participating in sports.
Your child’s doctor may recommend additional treatment methods, including:
Stretching exercises. Stretches for the front and back of the thigh (quadriceps and hamstring muscles) may help relieve pain and prevent the disease from returning.
Nonsteroidal anti-inflammatory drugs (NSAIDs). Drugs like ibuprofen, aspirin, and naproxen reduce pain and swelling.
Ice. Icing the inflamed area may reduce pain and swelling. Use cold packs for 20 minutes at a time, several times a day. Do not apply ice directly to the skin.
What is Knee OA?
What are the risk factors?
Osteoarthritis (OA) is a degenerative joint disease, characterised by the loss of articular cartilage. This is associated with periarticular bone response, the features of which can be seen on plain film radiographs.
Genetic factors – Estimates suggest a genetic component for hand, knee and hip OA at around 40-60%, however the specific genes involved remain largely unknown
Constitutional factors – Factors including increasing age, female gender, obesity, and low bone density (specifically in the progression of OA)
Local factors – Previous joint injury, occupational or recreational stresses on the joint, reduced surrounding muscle strength, or any joint laxity or malalignment
What are the symptoms of Knee OA?
The most common feature of knee OA is pain. Pain is typically felt around the knee, however can radiate to the thigh and hip. This pain is usually exacerbated by exercise and relieved by rest.
Patients will often have bilateral disease. There is associated joint stiffness, which can result in reduced function, and even joint swelling in severe cases.
On examination, there will be a reduced range of movement and often evidence of muscle wasting. Crepitus can be felt in severe cases.
How is Knee OA investigated?
Most cases of OA can be investigated with a plain film radiograph alone (lateral and antero-posterior (AP) views). The diagnostic features* (Fig. 2) that can be seen are (mnemonic LOSS):
Loss of joint space
Osteophytes -> try to widen surface of bone
Subchondral sclerosis -> whitening of bone
Subchondral cysts -> lesions
How is Knee OA treated?
Management
Initial Management
Lifestyle modifications play an essential part of the management plan, including weight loss, regular exercise, and smoking cessation. Adequate pain control is important, using the WHO analgesic ladder, to ensure ongoing mobility and quality of life.
Physiotherapy is commonly used and should be provided for all individuals with OA, aiming to slow disease progression and improve joint mechanics.
If conservative management efforts do not work, surgical management is warranted, which is typically either total or partial knee replacement.
Surgical Management
Total knee replacement (TKR) is the standard treatment for advanced osteoarthritis (Fig. 3). During this procedure, plastic and metal inserts are used to replace bone and cartilage in all sections of the knee. The vast majority of total knee replacements will function for at least 10 years and the majority of patients experience a significant reduction in knee pain.
Around 10% of patients only require partial (unicondylar) knee replacement, which is mainly used for those with disease localised to either the medial or lateral compartment, meaning the affected compartment will be replaced and healthy compartment left intact. Partial knee replacements are more conservative, therefore have faster recovery times, but may need conversion to total knee replacement at a later date.
What is RA?
Describe its morphology
- Genetic autoimmune
- Production of rheumatoid factor production (Anti-IgG Ab) that leads to an autoimmune response
- It is macrophage mediated local joint inflammation and destruction
Morphology: erosion of the articular cartilage, pannus (inflamed thickened hyperplastic synovium with papillary injections) and Fibrous Ankylosis (bone fusion)
