July 18, 2024

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.

Osteochondritis dissecans (Knee)
Osteochondritis dissecans (Knee)

Classification of OCD Knee

  1. Juvenile and Adult form
  2. 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)

Plica syndrome
Plica syndrome

During development in the embryonic period, the knee is divided into 3 cavities

  1. Large Supra patellar pouch
  2. Medial compartment
  3. 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