Most common reason for litigation against orthopaedic surgeons in THR
Usually from lengthening
1. Nerve palsy
Sciatic nerve - tolerate average 4.4cm lengthening
Common peroneal nerve - tolerate average 2.7 cm lengthening
Lengthen by up to 15-20% of the resting nerve length
- but in reality is unknown and multifactorial
1. Spinal dysraphism
Failure of the neural tube to close (i.e. spina bifida + failure of neural tube development)
May see one of 5 telltale skin defects
- tail
- skin dimpling
- sacral pit
- hair tuft
- lipoma
Myelodysplasia: Any developmental defect of the spinal cord
2. Spina Bifida Cystica
Prevalence of 25-100%
Ambulation
- walking decreases incidence
Age
- worse with young onset
Exact biomechanical explanation of origin & progression of curves unclear
Associated with
- weakness
- poor muscle control
- no proprioception
Lateral curvature of the spine 2° to vertebral anomaly
- causes an imbalance in longitudinal spine growth
True incidence unknown
F > M
Typically Thoracic
No association in twins / suggests not inherited
5% risk in family if complex multi-level
< 4 years by definition
M : F
75% left thoracic
Actually very uncommon
- likely most patients once had spinal dysraphism (Arnold-chiari / syrinx / tethered cord)
- reduced by prenatal folate
Age < 1
- 90 % spontaneously regress
- very important
Disproportionate dwarfism with a short trunk
Problems with dwarfism, spine, vision and hearing
Primary involvement of vertebrae & epiphyseal centres of limbs
Resulting short-trunk dwarfism
- Limb are short, but trunk is even shorter
(cf Metaphyseal Chondrodysplasia - Short limbed Dwarf)
Abnormality of type 1 collagen
- amino acid substitution of glycine with another amino acid
- prevents triple helix formation
Many many deformities described
- some 286 mutations of Type 1 collagen described
There are actually now 7
Type I
- mild
- AD
- blue sclera
Benign, bone-forming neoplasm
- characterized by a small nidus of neoplastic tissue
- surrounded by a wide zone of mature, reactive bone
10% of benign bone tumours
Age 5-25
M:F 2:1
Unknown
- thought may be glomus tumour of bone
Pain secondary to prostaglandin production