Knee Osteochondritis Dissecans , Wilson's Test - Everything You Need To Know - Dr. Nabil Ebraheim

Video Description

Dr. Ebraheim’s educational animated video describes the condition of Osteochondritis Dissecans of the knee joint.

Osteochondritis Dissecans is a condition that affects the articular cartilage and the subchondral bone of the knee. The lesion usually occurs in the knee on the lateral and posterior aspect of the medial femoral condyle. (70% of lesion are in the posterolateral aspect of the knee)
Distribution of OCD lesion around the knee
•Medial femoral condyle 85%.
•Lateral femoral condyle 13%
•Patella 1%
•Trochlea 1%
The chances of the lesion occurring at the lateral condyle and patellar aspect of the knee is rare. Lateral condylar and patellar lesions will have a bad prognosis.
The mechanism and causes of injury for OCD lesions:
May be multifactorial (vascular?). It is usually caused by repetitive overloading causing fragmentation and separation of bony fragments. It occurs in juveniles with an open epiphysis usually during the ages 10-15 years. Prognosis is usually very good. It can also occur in adults with a less favorable prognosis.
Four stages:
•Stage I: depressed OCD: intact cartilage. Small areas of compressed subchondral bone.
•Stage II: partially detached fragment.
•Stage III: completely detached bit non-displaced. Most common type.
•Stage VI: completely detached & displaced: displaced fragment can be a loose body.
Symptoms and physical exam:
•Activity related vague pain
•Poorly localized tenderness
•Effusion
•Swelling and stiffness with or without mechanical symptoms
•Mechanical symptoms indicates an advanced problem.
Wilson’s test0
The Wilson's test is a test used to detect the presence of Osteochondritis Dissecans of the knee. Ask the patient to sit on a table with his legs dangling over the edge. The patient’s knee should be flexed at 90-degree angle. Grasp the patient’s leg and internally rotate the tibia. Instruct the patient to extend the leg until pain is felt. The test is positive when the patient reports pain in the knee about 30 degrees from full extension. When rotating the leg back in its normal position the pain disappears. Internal rotation causes impingement of the tibial eminence on the OCD lesion of the medial femoral condyle which causes pain. External rotation moves the eminence away from the lesion, which relieves the pain.
Imaging
•X-rays: weight bearing AP & lateral view radiographs. Tunnel view (intercondylar notch view).
•MRI: check the size of lesion, signal intensity surrounding the lesion and any presence of loose bodies.
Prognosis
•Age: prognosis correlates with age. Younger the age, better the prognosis.
•Location: lesions in the lateral femoral epicondyle and patella have a worse prognosis.
•MRI findings: synovial fluid appearing behind the lesion on MRI correlates with a aworse prognosis. A fluid signal on MRI behind the lesion indicates that the fragment is unstable and is less likely to heal.
•Adult has worse prognosis.
Treatment
•Non-operative treatment: observation, limitation of activity, crutches, trial of non-weight bearing for six weeks and close follow-up.
Indication of nonoperative treatment: stable lesions in children with open physes. The majority will heal as long as the physes is open (good prognosis).
•Operative treatment: indicated if the fragment is detached, unstable or loose in patients where the physes has already closed, is near closing or if there is failure of the non-operative treatment. Surgical treatment usually includes arthroscopy and removal o loose fragment or fixation of unstable lesion or micro-fracture which is drilling of the lesion. Arthroscopic drilling of the subchondral bone is done in children who approach skeletal maturity. Drilling of the lesion has a high success rate especially if the lesion is stable.


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Background music provided as a free download from YouTube Audio Library.
Song Title: Every Step