Osteochondritis Dissecans

Definition

Localised injury or condition affecting an articular surface that involves separation of cartilage & subchondral bone

Epidemiology

Two distinct populations of patients involved

Juvenile form

Children & adolescents between 5-15 years with open physes

Adult form

Older adolescents & adults

Rare in patients younger than 10 & older than 50

Most frequently in young male athletes

Can be multifocal & familial

Areas affected

Lateral surface medial femoral condyle knee

Posteromedial corner talus in the ankle

Superomedial part femoral head

Humeral capitellum

1st metatarsal head

Knee most commonly affected joint - 75%

Aetiology

Trauma (repeated minor trauma)

Ischaemia

Defect of ossification

Genetic

Trauma

Indirect trauma most likely as the posterolateral area of the MFC most involved

Repeated minor trauma

Fairbank proposed impingement of the tibial spine on lateral part of the MFC during internal rotation of the knee

Aichroth proposed that odd facet of patella articulates with lateral part of the MFC during flexion & causes lesion with patellofemoral contact

The osteochondral fractures of the LFC after patellar dislocation is not OCD

Ischaemia

Abnormal subchondral bone structure predisposes to pathological fracture

Enneking suggested that subchondral bone has vascular end-arterial arcade (mesentery like) & so ischaemic segment of bone could occur & act as sequestrum

Granulation tissue thus forms between the viable & necrotic bone

The lesion of osteonecrosis should be distinguished

Histological studies of loose bone showed no AVN

Defects of Ossification

Abnormality of ossification that fails to heal

Stress to the affected segment leads to partial or complete detachment

Some investigators suggested that irregularity or roughening of the distal femoral epiphysis may be normal

Genetic Causes

Families identified with predisposition of OCD in multiple joints

Associations with OCD and

Dwarfism

Tibia vara

Perthes disease

General Treatment Principles

Nonoperative

Load reduction

Restrict activity

Complete healing in children may take 2 years

Consider operative intervention if

Loose bodies present

Symptoms > 6-12 months

Healing unlikely from radiographic indices

If operate then options are

Debride & drill to promote healing }

Reattach fragment } protected WB & early ROM

Mosaicoplasty }

Salvage procedure (eg HTO)

Knee

Clinical

Early poorly-defined symptoms

Pain

Swelling

Progression associated with

Catching

Locking

Giving way

Intermittent & related to activity or exertion

Age of patient at time of presentation is primary determinant of treatment

Examination

Lateral aspect of medial femoral condyle most commonly affected

Medial femoral condyle tenderness & crepitus

Joint effusion

Wilson Test positive

Flex to 90°

Internal tibial rotation

Slow extension giving pain

Seen at 30° of extension

Relieved by external rotation of tibia

Imaging Studies

MFC affected in 75-85% of cases

1/4 on the weight bearing area

Notch A-P XR best way to visualise this lesion

Lateral XR has two lines described by Harding

- One along the posterior femoral cortex &

- One along Blumensaat line

- Segment A is above Blumensaats line

- Segment B is in area between lines

- Segment C is in area below the posterior femoral cortex line

Arc between these two lines is common site for lesions

Cahill & Berg - Classified A-P radiograph into 5 segments

- Medial Tibiofemoral area is segments 1 & 2

- Notch area is 3

- Lateral Tibiofemoral area is segment 4 & 5

The same authors described the lesions from bone scan performed 6 weekly

Four stages of lesions

- Stage 1 - Visible on plain XR but normal bone scan

- Stage 2 - Visible on plain XR & ↑ uptake on scan

- Stage 3 - Above with ↑ uptake in whole of MFC

- Stage 4 - All of above & ↑ uptake in area of adjacent tibial

condyle

They used this as guide for treatment with stage 2 & above thought to heal due to osteoblastic activity

MRI

More sensitive than plain XR & correlates closely with arthroscopic findings (XR does not)

Determination of

Displacement of fragment

Fluid interfaces

Integrity of the articular surface

Improved with Gadolinium contrast

Arthroscopic Classification

Described by Guhl & used to plan operative management

- Intact lesions – cartilage intact

- Lesions showing early separation

- Partially detached lesions

- Craters with loose bodies

salvageable

unsalvageable

Natural History & Treatment

Dependent on age of patient at presentation

Juvenile lesions frequently heal

Once separation of fragment of bone from the base occurs healing unlikely

Healing of articular cartilage occurs through fibrocartilaginous metaplasia

Less resilient & degeneration more rapid

Principles of Operative Treatment

Restoration of articular congruity

Enhancement of local blood supply to fragment or crater

Rigid fixation of unstable fragments

Protected weight-bearing with motion ASAP

Accepted Indications

Symptomatic loose bodies

Detachment during observation

Predicted physeal closure within 6-12 months

Juvenile lesions that remain symptomatic despite non op treatment

Established non union of fragment

Surgical options

Excision of fragment & drilling the base

- Poor results when large & in weight bearing area

- But may be better to excise than reattach poorly fitting fragment

Reattachment of fragment

- Bone graft may be used & fixation varies from K-wires to Herbert Screws

- Articular congruity of paramount importance

Osteochondral allo/ auto grafts

- Good early results with the autografts obtained from around the knee – Mosaicoplasty

Summary of Treatment Plan

Children with symptomatic lesion managed non op with limitation of activity & protected weight-bearing

Operative intervention if

- Loose bodies present

- Symptoms > 6-12 months

- Healing unlikely from radiographic indices

Preserve the fragment if possible

In adults

- Lesions with intact articular cartilage drilled in retrograde fashion

- Separated lesions treated with curettage & drilling of base of lesion & replacement of lesion

- May need bone grafting to produce congruity of articular surface

- Excise only if small fragment or not reconstructable

- Consider mosaicoplasty

- Protected weight-bearing with early motion essential

In much older adult may consider TKR or HTO with advanced secondary Osteoarthritis

Ankle

Clinical Presentation

Catching with walking or active ROM

First seen in early adulthood usually

Often history of trauma

Swelling frequent & initial symptoms attributed often to sprain

Lesions classically

- Anterolateral

- Posteromedial

Posteromedial often asymptomatic with no history of trauma

Physical Examination

Crepitus or joint effusion

Well defined tenderness

Pain with compression of the tibiotalar joint common

Imaging Studies

Berndt & Harty classification system of osteochondral talar lesions

- Stage 1 - Small area of subchondral bone compression

- Stage 2 - Partially detached flap of cartilage

- Stage 3 - Completely detached fragment that lies in the bed (most

common)

- Stage 4 - Loose body

CT scan will help distinguish from cystic lesions or osteonecrosis

Help determine size & location of lesion

MRI will help distinguish between the Stage 2 & 3 lesions with the fluid interface

Aetiology

More clear relationship with trauma than in other sites

Impingement of talus on the tibia or fibula produces lesion

Cadaveric studies by Berndt & Harty showed

- Anterolateral lesions by talar impaction on fibula during inversion in dorsiflexion

- Posteromedial lesions by impaction against the posterior tibial plafond during inversion in plantarflexion

Canale had found that the lateral lesions more likely to be traumatic in nature

The lateral lesions are wafer shaped but medial lesions dome-shaped

Natural History & Treatment

Suggest that Stage 1 & 2 lesion be treated non op with protected weight-bearing

The Stage 3 & 4 should have debridement & drilling of base but the anterolateral lesions more likely to give symptoms & lead to greater degree of degenerative changes than the medial lesions

Arthroscopic debridement useful but often difficult to access the posteromedial lesion & so arthrotomy may be required

Elbow

Clinical Presentation

Pain, swelling & loss of motion

Adolescence to early adulthood

Uncommon but related to overuse particularly throwing

Little Leaguers Elbow - valgus compression overuse in immature elbow causing OCD of the capitellum

Pappas divided into 3 categories dependant on age of patient

- Category 1 - patients < 13 years of age

- Category 2 - 13 years to adulthood

- Category 3 - adults

Better prognosis seen in younger patients

Imaging Studies

X-ray often sufficient to make diagnosis

See area of rarefaction or radiolucency on lateral or central portion of the capitellum

Loose bodies in late stages

Radial head hypertrophy also in later stages

If entire capitellum involved in child 4-8 years of age then suspect Panner’s disease

MRI very sensitive as per previous text

Aetiology

Trauma

Proposed by many investigators

Valgus overload on the radiocapitellar joint

Fatigue failure of the subchondral area

Separation of the bone from its bed

Overlying cartilage fails under shear stress & separates

The cartilage remains alive with synovial nutrition but bone avascular

Ischaemia

Predominant blood supply to the capitellum from posteriorly located vessels

Thus tenuous blood supply & at risk here

Natural History & Treatment

Poorly understood

Treatment usually involves debridement of loose bodies

Drilling of base of lesion did not affect outcome

Loss of full extension of elbow common

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