Osteochondritis dissecans (OCD) is the condition due to inadequate blood supply where the underneath portion of the joint becomes avascular.
80% of cases of lesion occur in the Lateral part of the medial femoral condyle, exactly where the patella makes contact with the knee in full flexion.
In this area subchondral bone becomes avascular and within this area, an ovoid osseocartilaginous segment is demarcated from surrounding bone.
Cartilage intact with fragment stable: Fragment separated but remains in position and fragment breaks free and becomes loose bodies.
Classification of OCD Knee
- Juvenile and Adult form
- Stable and Unstable form
Clinical Features
Generally seen in the age group of 15-20 years
Complaints of intermittent ache or swelling
Attacks of giving away
Locking
Quadriceps wasting with small effusions can be seen in long term
Diagnostic signs of OCD knee
Tenderness is localized to one femoral condyle
Wilson’s sign is positive
Wilson sign: Knee flexed 90° rotated medially and gradually straightened pain is felt but repeating the test with knee rotated laterally it is painless
Imaging
X-Ray shows the line of demarcation ( usually lateral part of medial femoral condyle)
Special view: Intercondylar (tunnel) view
Once the fragment is detached we can see the empty hollow sign (possibly loose bodies)
MRI is used to locate the site, size, and activity of the lesion
Arthroscopy is diagnostic and helps to know whether OCD is either stable or unstable
Differential diagnosis
AVN of the femoral condyle
Treatment Options for OCD Knee
Treatment is decided according to the stage of the lesion
In Juvenile cases, they are typically stable
In Adult cases, OCD is generally unstable
Earliest stage
As the treatment is needed but activity is curtailed for 6-12 months.
Small lesions often heal spontaneously
If the fragment is unstable or in later stages
Surrounded by the clear boundary with radiographic sclerosis
Treatment depends upon the size and age of the patient
Small fragments: (< 1cm)
Fragments are removed by arthroscopy, the base is drilled which is later filled by fibrocartilage
Larger Fragments: (>1 cm)
In younger patients with open growth plates, is fixed in-situ with a herbert screw
In older patients, removal of unstable fragments and cartilage repair technique, and microfracture or Autologous cartilage implantation (ACI)
Plica Syndrome
Remnant of embryonic synovial partition which persists till adult life
One of the important causes of knee pain
(Plicare- to fold)
During development in the embryonic period, the knee is divided into 3 cavities
- Large Supra patellar pouch
- Medial compartment
- Lateral compartment
Separated from each other from membranous septa
Later during development, this septa disappeared but in around 20% of cases, it persist as a plica.
Mostly in the medial infrapatellar fold ( ligamentum mucosum)
Less often in the suprapatellar curtain
There will be clicking on the medial aspect of the knee when flexed to 90° as hypertrophic plica rubs against the medial condyle
Arthroscopic removal of plica is done
