Usually occurs in young people
- often previous history of tendonitis ± steroid injections
Usually at level of inferior pole of patella
- less common at tibial tubercle
- mid-substance ruptures rare
Severe pain
Palpable defect
Extensor deficit / unable to SLR
Patella alta / high riding patella
Osteochondritis Dissecans
- separation of avascular fragment of bone & cartilage
M : F = 2:1
Mean age 18 years
- can present as young as 9
4:1000
Developmental Anatomy
Knee joint first appears as a mesenchymal cleft at 8 weeks gestation
- ACL and PCL separate entities by week 10
1. Seebacher's 3 layers of the medial knee
Layer 1
- sartorius and sartorius fascia
Layer 2
- superficial MCL
- posterior oblique ligament
- semimembranosus
Layer 3
- deep MCL (meniscofemoral and meniscotibial ligament)
- posteromedial capsule
2. MCL
Superficial MCL
>55 Often mid 30's
Reproduce the normal anatomical centre of rotation
Restore femoral offset
Maintain equal leg lengths
Usually template off normal hip
1. LLD
2. Offset
3. Femoral component
4. Acetabular component
5. Osteotomy / femoral seating
Templating
Approach
Fixation
Bearing Surface
Head Size
Offset
Disabling hip pain
Severe functional impairment
Failed non operative management
Painless deformity
Migration of the femoral head past the medial wall of the acetabulum / ilioischial line
Centre edge angle > 40o
Primary
Otto's Disease
- bilateral in one third
- middle aged females
- pain & decreased ROM early
- coxa vara & OA common
- ? causally related to osteomalacia
Extraskeletal bone formation in periarticular tissues
- HA crystals within osteoid matrix
Different to calcification
- osteoid matrix laid down
1. Myositis Ossificans
- post traumatic
Intrinsic
Infection
Loosening
Thigh pain in uncemented
- micro motion at distal end of stem
- modulus mismatch
Stress fracture / insufficiency fracture
- pubic rami, sacral
Intra-operative fracture
Prosthesis failure
Subtle instability
Extrinsic