Knee Pain- Common Knee Problems

Knee Pain

Common Knee Problems

A common knee problem could be patellar chondromalacia. This chronic pain is due to softening of the cartilage beneath the knee cap. Pain is from mild to complete erosion of the cartilage in the back of the knee cap. It causes pain in the front of the knee. It occurs more in young people. It becomes worse from climbing up and down stairs. Treatment for patellar chondromalacia usually includes therapy and NSAIDS. Another common knee problem could be Patellar Bursitis.knee This is characterized by pain and inflammation over the front of the kneecap. This occurs when the bursa becomes inflamed and fills with fluid at the top of the knee. It causes pain, swelling, tenderness, and a lump in the area on top of the kneecap. Lateral Collateral Ligament Rupture usually occurs as a result of sports activities. Medial Collateral Ligament Rupture is an injury to the ligament on the inner part of the knee. It is the most commonly injured knee ligament. Anterior Cruciate Ligament Tear involves valgus stress to the knee. Usually the patient will have swelling and hematoma. It can be diagnosed by MRI or a positive Lachman’s test. Patellar Tendonitis is characterized by inflammation and pain located inferior to the knee cap area. The meniscus is a cusion that protects the cartilage of the knee. A meniscal injury will cause pain of the medial or lateral side of the knee. The outer 30% of the meniscus has blood supply. Meniscal tears can be diagnosed by MRI or a positive McMurrays test. kneeePatient with meniscal tears typically have a history of locking, swelling, and instability of the knee. Arthritis of the Knee Joint is characterized by progressive wearing away of the cartilage of the joint. The knee is a common part of the body that is most affected by arthritis. Knee arthritis causes decreased joint space. A Baker’s Cyst causes swelling in the back of the knee filled with synovial fluid. The cyst is between the semimembranous and medial gastrochnemius muscles. Gout is a type of arthritis or joint inflammation caused by an excessive level of uric acid in the blood. It can affect any joint especially the big toe. The gout crystals look like needles and have a negative birefringence.

Osteonecrosis of the Knee

There are three different types of osteonecrosis of the knee. There is Spontaneous Osteonecrosis of the Knee, Post Arthroscopic Osteonecrosis of the knee, and Secondary Osteonecrosis of the knee. Osteonecrosis is further classified by severity using Ficat Stages of Knee Osteonecrosis. In Stage I, the x-ray appears normal. Stage II, Sclerosis of the condyle is present. In Stage III, the crescent sign is found as well as a subchondral fracture. Stage IV, there is a collapse of subchondral bone.

ficatSpontaneous Osteonecrosis of the Knee typically occurs in females older than 55. Usually one joint and one compartment is affected (medial femoral compartment). No etiology is known. Symptoms typically consist of a sudden onset of severe pain with decreased range of motion as well as swelling in the knee. X-rays will probably appear to be normal. An MRI is helpful, the provider may find a crescent shaped lesion. This conditionspontaneous can cause arthritis. If severe knee pain is present in a middle aged or elderly female patient, and the x-ray is negative, the provider should order an MRI to rule out osteonecrosis of the knee. Treatment consists of protected weightbearing as well as therapy and NSAIDs. An arthroplasty may be required when conservative treatment fails. A unicompartmental knee arthroplasty will be performed for small lesions. A total knee arthroplasty will be completed for large lesions or collapse.

Post Arthroscopy Osteonecrosis of the Knee most commonly occurs in middle aged secondarywomen after a knee arthroplasty. Secondary Osteonecrosis of the knee is common in women under 55 years of age and has associated risk factors. This condition involves more than one compartment or the metaphysis of the knee. Secondary Osteonecrosis occurs bilaterally in 80% of cases and multifocal lesions may be seen. There is a cause for Secondary Osteonecrosis of the knee, which is why it can be bilateral, multiple, and everywhere. Risk factors include:

  • Alcohol use
  • Sickle cell disease
  • Steroid usedissecans
  • Trauma
  • HIV medications
  • Gaucher Disease

 

These patients should be screened for other joint involvement. The lesion is a subcondylar insufficiency fracture and the patient will have severe pain with weight bearing either standing or sitting. An x-ray may show a wedge-shaped lesion and MRI is the better study. A differential diagnosis is Osteochondral Dissecans, which is located in the lateral aspect of the medial femoral condyle in younger patients. Other differentials include: Occult trauma, bone bruise and overuse, as well as transient osteoporosis which is found more in middle-aged men and usually in the hip rather than the knee. Treatment consists of NSAIDs, a decrease in activity and weightbearing, and physical therapy. A scope surgery may be necessary to remove loose fragments or core decompression for lesions not extending to the joint. An Osteocondylar allograft may be performed for large, painful lesions in younger patients. A total knee replacement may be done for larger lesions, for collapse, or if multiple compartments are involved. Conservative treatment is not as successful with secondary avascular necrosis. Without surgery, secondary AVN will advance to osteoarthritis. Bisphosphonates have no effect on knee osteonecrosis.

Q-Angle of the Knee

A well-functioning knee joint is important for mobility. The knee must be able to support the weight of the body during activities such as walking or running.

What is a Q-angle? knee anatomy

The Q Angle, or quadriceps angle, is the angle between the quadriceps tendon and the patellar tendon. An increased Q-angle is a risk factor for patellar subluxation.

How do you measure the Q-angle?

First, you will need to find the patella and its border. Then, you will need to find the center of the patella. You will then need to find the tibial tubercle and draw a line from the ASIS to the center of the patella and a second line from the tibial tubercle through the center of the patella.

normal qThe Q-angle is formed in the frontal plane by the two line segments. It is the angle formed by a line drawn from the Anterior Superior Iliac Spine (ASIS) to the center of the patella. A second line is drawn from the center of the patella to the tibial tubercle. The angle formed by the two lines is called the Q-angle. The normal Q-angle is variable. In males, the angle is usually 14° and 17° in females. A wider pelvis and an increased Q-angle in females is linked to knee pain, patellofemoral pain, and ACL injury. The alignment of the patellofemoral joint is effected by the patellar tendon length and the Q-angle. It is best to measure the Q-angle with the knee in extension as well as flexion.increased q

A larger Q-angle plus a strong quadriceps contraction can dislocate the patella. The Q-angle is increased by:

  • Genu valgum
  • External tibial torsion
  • Femoral anteversion
  • Lateral positioned tibial tuberosity
  • Tight lateral retinaculum

A CT scan study of the patellofemoral articulation is found to be very helpful.

Haemarthrosis of the Knee

Hemarthrosis is blood inside the knee or bleeding into the knee joint space. The swelling and fluid inside the knee joint is usually relieved with an aspiration. During the aspiration, the physician will insert the needle on the lateral side of the knee, just above the upper border of the patella. The needle enters below the patella into the suprapatellar bursa which is continuous with the joint cavity. This aspiration technique is different than how physicians perform injections. For a knee injection, the needle is inserted at the lower border of the patella on either side of the patellar tendon at the soft spot.

aspiration v inspirationThe color of the fluid aspirated—not bloody effusion—is probably due to synovial irritation caused by chronic processes such as gout, pseudogout, arthritis, rheumatoid arthritis, or degenerative meniscus. A degenerated meniscus may be associated with swelling and fluid collection; usually not bloody. The peripheral portion of the meniscus is vascular (about 3-5 mm). The blood supply of the meniscus originates from the medial and lateral genicular arteries. Although a degenerative meniscus effusion is not bloody, a traumatic tear of the meniscus may cause bleeding inside the knee joint.

arthrA bloody effusion could be trauma related or non-trauma related. For example, hemarthrosis can be caused by trauma or injury to the structures of the knee such as the ACL, PCL, or meniscus. Hemarthrosis can also occur due to tibial plateau fractures, chondral fractures, patellar dislocations, or a meniscal tear. Non-traumatic conditions that can cause hemarthrosis include: PVNS, sickle cell anemia, hemophilia, anticoagulation, or hemorrhage following total knee replacement.

Hemoarthrosis from trauma or injury indicates a significant knee injury such as ACL (75-80%) or a meniscal tear. If aspirations of the knee after trauma shows hemarthrosis, early evaluation of the injury may be necessary to define the extent of damage. The physician may get an MRI early.

meniscusAbsence of hemarthrosis does not mean a less severe ligament injury—the blood may escape without distending the capsule. A severe injury may cause minimal or severe joint effusion. More than 20cc of fluid may affect the quadriceps function and prevent full extension of the knee. A hematoma should be evacuated. The bloody aspirate should be examined for fat to rule out a fracture. The aspirate may vary in color depending on the severity of the injury and the duration of the symptoms. Fat is less dense than blood and fat floats on the surface, whereas blood is heavier and stays on the bottom.

mri.The presence of a fat/fluid level is diagnostic of a fracture even if a fracture is not seen on an x-ray (occult). Fat/fluid level is usually seen with tibial plateau, chondral, and patellar fractures. The cross table lateral view of the knee shows it well. When a fat/fluid level is seen, look for intra-articular fractures. Lipohemarthrosis is only seen on horizontal x-ray beams with the beam parallel to the floor. It occurs in 40% of all fractures inside the joint.

lipohemoarthrosis