Relatively rare
Average age 50
Men 4:1 Women
Usually dominant arm
Primary
- associated with strenuous manual labour
Secondary
- trauma
- OCD
- synovial chondromatosis
- valgus extension overload / MCL insufficiency
Occurs 10% of supracondylar humeral fractures
- varus malunion
Lateral condyle fracture
- AVN trochlea
Growth arrest of medial aspect physis
- rare
- post traumatic
A valgus knee has a tibiofemoral angle of > 10o
Inflammatory
- RA
Increased pressure within a closed fibro-osseous space
Seen in athletes, associated with repetitive exertion
Leg
1. Anterior compartment
- anterior tibial artery
- deep peroneal nerve
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
Round or "D" shaped rather than crescenteric meniscus
- occupies > 70% of tibial surface
- 90% occur on lateral side
Uncommon
- 1:100
- usually presents in children & adolescents
Most common lower limb neuropathy
Valgus TKR - 3%
HTO - 10%
Direct Trauma / Compression
Knee Dislocation
Tibial fracture
Cast / Dressing
Lateral Meniscus Repair
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
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
Primary THR 1%
Revision THR 3%
DDH 5%
Sciatic nerve 90% of nerve palsy
Other
- femoral nerve
- CPN
- ulna / radial nerve from positioning
Direct
Laceration
- exposure / sciatic and superior gluteal nerve
- drill reamer / obturator nerve
- spike of cement / obturator nerve