The ends and the tips of a long bone that ossify from secondary centers are known as epiphyses.
1. Pressure Epiphyses:
- These epiphyses are articular that is they take part in joint formation.
- These epiphyses are the weight transmitting epiphyses.
- Examples are head of the humerus, lower end of the radius etc.
2. Traction Epiphyses:
- These are non-articular and do not take part in the formation of joints.
- They also do not take part in transmission of weight.
- They provide attachment to tendons of muscles.
- The traction epiphyses ossify later than the pressure epiphyses.
- Examples of these epiphyses are tubercles of humerus (greater tubercle and lesser tubercle) and trochanters of femur (greater trochanter and lesser trochanter).
3. Atavistic Epiphyses:
- These epiphyses are phylogenetically independent but they become fused in man.
- Examples are coracoid process of scapula and os trigonum.
4. Aberrant Epiphyses:
- As the name indicates (aberrant = not usual) these epiphyses are not always present.
- Examples are epiphyses at the head of the first metacarpal bone and at the base of other metacarpal bones.
Epiphysiodesis
- Phemister described epiphysiodesis in 1933, and his original technique, with minor modifications, has been widely used for limb-length equalization.
- Currently, epiphysiodesis is not recommended for shortening of > 5 cm.
- Phemister – Green technique: Rectangular piece of bone removed, growth plate curetted, the block of bone turned 180 degree and replaced.
- Bowen – Percutaneous epiphysiodesis
- Epiphyseal stapling
- Metaizeau – Percutaneous transphyseal screws
- White developed special hollow chisels to remove a square block of bone and curetted the physeal cartilage deep in the hole before replacing the bone block in a reversed position.
- A newer technique of epiphysiodesis involves the use of percutaneous instrumentation to obliterate the physis through small, cosmetically pleasing incisions.
Regardless of the technique used, careful timing and consideration of the final height of the knee are important.
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