B Assessment Bone Loss
Indications
1. Loosening
2. Infection
3. Instability
4. Periprosthetic fracture
etiology
A Osteolysis and Loosening
Definition
Biological response to particulate matter
- characterised by periprosthetic osteolysis
- stimulated by wear debris
- debris gains access to any area accessible by fluid
Sources of particulate debris
1. Wear
Mechanisms of wear
Proximal hamstring avulsions
Epidemiology
Adolescent apophyseal avulsion
- treat non operatively
- unless displaced > 2 cm
Adult
- soft tissue avulsion
Aetiology
Usually associated with sporting activities
- skiing
- water skiing
Violent contraction
- knee extended
- hip flexing
Anatomy
Heterotopic ossification
Definition
Pathological bone formation in soft tissues
Epidemiology
In elbow
- 3% of trauma
- 89% if head injury + trauma
Types
Completely different
1. Myosisitis Ossificans Circumscripta
- post traumatic
- more common
- recognised as a consequence of neurological injury
Synovial Chondromatosis
Definition
Chondroid Metaplasia of synovium affecting large joints
Nodules of hyaline cartilage
- formed in the subsynovial layer of joint capsules
Epidemiology
Rare lesion
Most common in 20's and 30's
Sex: M > F (2:1)
Monoarticular
Site
Multiple Hereditary Exostosis
AKA
Diaphyseal Aclasis / Multiple Osteochondromas
Definition
Heritable skeletal dysplasia
Epidemiology
AD with variable penetrance (96%)
Malignant Transformation
Incidence of malignant transformation much higher
- 10% overall
- 1 % / year
Chondrosarcoma (CS) > Osteosarcoma (OS)
Hip Dislocation
Incidence
Young men
Posterior / Anterior 9:1
Aetiology
High velocity injury
- head direction at impact decides direction of dislocation
Anterior Dislocation
Externally rotated & abducted leg
- flexion = inferior dislocation
Transient Osteoporosis Hip
Definition
Self limiting syndrome of unknown aetiology
- hip pain associated with osteoporosis of proximal femur
DDx
AVN
- AVN of the hip in pregnancy is rare but possible
- TOH tends to be diffuse on MRI, while AVN is localised
- extends to neck and metaphysis
- transient osteoporosis has normal bone scan
Incidence
Rare
- M: F 3:1
Background
Definition
Non-traumatic or traumatic condition of femoral head with bone death
Epidemiology
20 - 50 yo (average 38)
- M: F 4:1
NHx
70-80% with AVN will progress within 1 year
Background
Deformities
Mallet
- DIP flexed
- MTP / PIPJ neutral
Hammer
- PIP flexion
- DIPJ neutral / extended
Simple - MTP not involved
Complex - MTP hyper-extended
Claw
- PIPJ and DIPJ flexed
- MTPJ hyperextended
Curly toe
- PIP and DIP flexion