Pathology & Pathology & Biomechanics of Biomechanics of

Unicompartmental Unicompartmental ArthritisArthritis

John GoodfellowJohn GoodfellowNuffield Orthopaedic Centre, Oxford

Extremecase

Typical cases

• Antero-medial OA

• Functionally intact ACL

PosteriorPosteriorPosterior

Anterior

Anterior

Anterior

Preserved Cartilage

LostCartilage& Bone

Antero-medial OA

Preserved Cartilage

LostCartilage& Bone

Antero-medial OA

Varus deformitycorrects in

flexion

Medial collateralligament

tightPreventsligament

shortening

Loss of cartilage & bone

Varus deformity

Medial collateralligament

lax

Antero-medial OA

Varus deformitycorrects in

flexion

Medial collateralligament

tightPreventsligament

shortening

CorrectableVarus

Deformity

ACLIntact

ACL rupture

Loss of cartilage & bone

Posteriorly

Medial collateralligament

lax

Varus deformitypersists in

flexion

Medial collateralligament

laxMCL short

Fixed deformity

Extremecase

Extreme case

Deformity corrects in flexion

Bone preservedposteriorly

Deformity corrects

with stress

Anteromedial Osteoarthritis

• Cartilage loss limited to ANTERIOR TIBIAL PLATEAU

INFERIOR FEMORAL CONDYLE

• ACL INTACT

• CORRECTABLE VARUS DEFORMITY

Varus Valgus

Lateral X-ray

ANTERIOR

Posterior extent of cartilage loss correlates with the state of the ACL

ACL+

ACL+

ACL-Gross(sublux)

ACL?

AnteromedialOsteoarthritis

Thank you