Osteochondritis Dissecansof the Knee

Tim FranciscoOrthopedics Topic

Osteochondritis DissecansDefinition:

Idiopathic Lesion of subchondral bone that becomes necrotic.

With motion and lack of underlying support, the cartilage may degenerate and eventually a focal area of subchondral bone (with or without articular cartilage) will separate from adjacent bone

Osteochondritis DissecansIncidence

30-60/100,00010-20 years of age

can occur up through 50 years of age

Male/Female-3:1Right knee>Left

kneeBilateral 30%

2 Types Juvenile (JOCD)

before epiphyseal closure

Adult (ACOD or OCD)

closed physes

OCD: History1854: Broca postulated that spontaneous

necrosis and subsequent mobilization of fragments accounted for loose bodies

1870: Paget agreed and described OCD in the knee

OCD: History1887: König provided the term,

osteochondritis dissecans described trauma to articular surface

leading to necrosis and then zone of “dissection inflammation

No histologic evidence for an inflammatory component

OCD: Etiology

1 Exogenous Trauma

2 Endogenous Trauma

3 Ischemia

4 Abnormal ossification

5 Genetic 6 Combination

Many etiologies have been proposed and investigated.

OCD: EtiologyTrauma likely a key factor, especially in

JOCD40% relate Hx of mild to moderate knee

trauma Cyclic or repetitive trauma

1976 Linden reports incidence related to popularity of sports

1975 Cahil notes average age from 12.9 to 11.3 years with in females with JOCD. He also relates this earlier participation in organized sports

OCD: Clinical Presentation

Vague symptoms of low grade knee pain Usually of several months duration related to level of physical activity

No acute trauma but possible past Hx of trauma

Swelling, locking, crepitus may be present

OCD: Physical Exam

Exam may be normal

Joint effusionCrepitusPainful joint motionPalpable loose

body

Localized pain to palpation at the lesion medial femoral

condyleCommon finding of

thigh atrophy

OCD: Physical ExamWilson’s test (Positive for lesions in classic

site) Patient seated with 90° knee flexion examiner internally rotates tibia then

extends knee Patient experiences pain at 30° of flexion External rotation of tibia relieves pain

Anterior tibial spine impacts on the medial femoral condyle

OCD: Differential DXMeniscal tearsOsteochondral FractureOsteonecrosisDJDMultiple epiphyseal dysplasia

OCD: Diagnostic StudiesRadiographic examination diagnostic

AP Lateral Patellofemoral

Tunnel view most important

Insert xrays here

A/P View

Tunnel View

OCD: Diagnostic StudiesMRI

Assess articular cartilage integrity Assess lesion stability less useful for identifying loose bodies

T1 weighted coronal

T1 weighted sagittal

T2 weighted sagittal

OCD: Diagnostic StudiesBone Scintigraphy

prognostic indicator Monitor lesion healing with serial scans Classification schemes

OCD: Diagnostic StudiesArthroscopy

Definitive assessment of lesion stability and articular cartilage integrity

Identification of loose bodies Classification Schemes Treatment

OCD: ClassificationMRI

1. Junction of fragment and underlying bone

2. Discreet, round homogeneous area deep to lesion

3. Focal defect in articular cartilage 4. Line traversing cartilage and

subchondral bone

OCD: ClassificationBone ScintigraphyStages I-IV have abnormal radiographs

Stage 0 Normal knee Stage I normal bone scan poor Stage II isotope uptake Stage III isotope uptake in lesion and femoral

condyle Stage IV isotope uptake in adjacent tibial plateau

OCD: ClassificationArthroscopic appearance

Type I intact articular surfaces, not mobile

Type II early separation, intact articular cartilage but fragment mobile

Type III disrupted articular surface Type IV crater with loose or fragmented

lesion

Partially detached lesion Elevation of lesion demonstrating the crater

OCD: PrognosisJOCD: generally good prognosis

50% spontaneously heal within 10-18 monthscompliant patient, stable lesion, not near age of

physeal closureAOCD or OCD: worse prognosis with

physeal closureLinden reported 80% of patients showed evidence

of DJD 10 years earlier than matched controls included all 3 compartments many had loose bodies

OCD: TreatmentTreatment based on

lesion size, stability, symptoms, skeletal maturity

Goals eliminate symptoms restore joint surface healing of fragment avoiding long term degenerative changes

OCD: TreatmentNonsurgical indications

All JOCD except for loose or detached bodies

Not much role for AOCD, even with stable fragment.Trial of conservative treatment?

Compliance is necessary

OCD: Treatment (non-surgical)

10-12 weeks Relative rest with or without protective

weight bearing Immobilization should be avoided b/c of

detriment to articular cartilageDecrease activity to achieve pain

free status

OCD: Treatment (surgical)

Indications Failed conservative treatment unstable lesions detached lesions skeletal maturity

Goals Enhance vascularization of fragment to encourage union reduction for anatomic restoration of joint surface enhance revascularization of replaced fragment to promote

union

OCD: Treatment (surgical)

Removal of loose bodies Every attempt should be made to replace the fragment

especially on weight bearing surfaces• long term results of fragment removal poor

Preparation of fragment and base of lesion is essential curette fibrous tissue drill subchondral bone crater add cancellous bone graft if surface not

congruous

OCD: Treatment (surgical)

Drilling K wireBone peg fixationPin fixationCannulated screwHerbert screw

Retrograde bone grafting

Fragment removal with drilling and abrasion

Osteochondral allografts

OCD: SummaryEarly recognitionStaging of lesion as to stability, size, skeletal

maturity to determine treatment plansFollow-up to monitor healingGoals

eliminate symptoms restore joint surface healing of fragment avoiding long term degenerative changes