Osteochondritis Dissecans of the Knee

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Osteochondritis Dissecansof the Knee

• Tim Francisco
• Orthopedics Topic

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Osteochondritis Dissecans

• Definition
• 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

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Osteochondritis Dissecans

• Incidence
• 30-60/100,000
• 10-20 years of age
• can occur up through 50 years of age
• Male/Female-31
• Right kneegtLeft knee
• Bilateral 30

• 2 Types
• Juvenile (JOCD)
• before epiphyseal closure
• Adult (ACOD or OCD)
• closed physes

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OCD History

• 1854 Broca postulated that spontaneous necrosis
  and subsequent mobilization of fragments
  accounted for loose bodies

• 1870 Paget agreed and described OCD in the knee

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OCD History

• 1887 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

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OCD Etiology
Many etiologies have been proposed and
investigated.

• 1 Exogenous Trauma
• 2 Endogenous Trauma
• 3 Ischemia

• 4 Abnormal ossification
• 5 Genetic
• 6 Combination

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OCD Etiology

• Trauma likely a key factor, especially in JOCD
• 40 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

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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

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OCD Physical Exam

• Exam may be normal
• Joint effusion
• Crepitus
• Painful joint motion
• Palpable loose body

• Localized pain to palpation at the lesion
• medial femoral condyle
• Common finding of thigh atrophy

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OCD Physical Exam

• Wilsons 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

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OCD Differential DX

• Meniscal tears
• Osteochondral Fracture
• Osteonecrosis
• DJD
• Multiple epiphyseal dysplasia

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OCD Diagnostic Studies

• Radiographic examination diagnostic
• AP
• Lateral
• Patellofemoral
• Tunnel view most important

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Insert xrays here
A/P View
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Tunnel View
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OCD Diagnostic Studies

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

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T1 weighted coronal
T1 weighted sagittal
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T2 weighted sagittal
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OCD Diagnostic Studies

• Bone Scintigraphy
• prognostic indicator
• Monitor lesion healing with serial scans
• Classification schemes

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OCD Diagnostic Studies

• Arthroscopy
• Definitive assessment of lesion stability and
  articular cartilage integrity
• Identification of loose bodies
• Classification Schemes
• Treatment

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OCD Classification

• MRI
• 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

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OCD Classification

• Bone Scintigraphy
• Stages 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

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OCD Classification

• Arthroscopic 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

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Partially detached lesion
Elevation of lesion demonstrating the crater
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OCD Prognosis

• JOCD generally good prognosis
• 50 spontaneously heal within 10-18 months
• compliant patient, stable lesion, not near age of
  physeal closure
• AOCD or OCD worse prognosis with physeal
  closure
• Linden reported 80 of patients showed evidence
  of DJD 10 years earlier than matched controls
• included all 3 compartments
• many had loose bodies

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OCD Treatment

• Treatment based on
• lesion size, stability, symptoms, skeletal
  maturity
• Goals
• eliminate symptoms
• restore joint surface
• healing of fragment
• avoiding long term degenerative changes

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OCD Treatment

• Nonsurgical 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

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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 cartilage
• Decrease activity to achieve pain free status

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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

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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

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OCD Treatment (surgical)

• Drilling K wire
• Bone peg fixation
• Pin fixation
• Cannulated screw
• Herbert screw

• Retrograde bone grafting
• Fragment removal with drilling and abrasion
• Osteochondral allografts

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OCD Summary

• Early recognition
• Staging of lesion as to stability, size, skeletal
  maturity to determine treatment plans
• Follow-up to monitor healing
• Goals
• eliminate symptoms
• restore joint surface
• healing of fragment
• avoiding long term degenerative changes