Line 1: |
Line 1: |
| ==Introduction== | | ==Introduction== |
− | The '''physis''' consists of four zones: | + | The '''physis''' allows long bones to continue to grow in length after birth and consists of [[Bones - Anatomy & Physiology#Bone Growth|five zones]]. |
− | #'''Reserve zone''': adjacent to the epiphysis, where the chondrocytes divide and produce matrix
| |
− | #'''Proliferating zone''': chondrocyte division produces organised columns extending away from the epiphysis. The true germinal cells of the physis are closest to the epiphysis.
| |
− | #'''Hypertrophic zone''': chondrocytes increase in volume (80%) a,d ùatrox decreases and undergoes biochemical changes in preparation for calcification.
| |
− | #'''Provisional calcification zone''': matrix becomes seeded with calcium phosphate. | |
| | | |
| The physis is weaker than the surrounding ligaments and bone, and therefore most '''susceptible to injury'''. | | The physis is weaker than the surrounding ligaments and bone, and therefore most '''susceptible to injury'''. |
| | | |
− | The physis is weakest at the junction between the proliferative and hypertrophic zones, and the '''hypertrophic zone''' itself is structurally weak due to the large cell:matrix ratio. | + | The physis is weakest at the junction between the proliferative (aka maturation) and hypertrophic zones, and the '''hypertrophic zone''' itself is structurally weak due to the large cell:matrix ratio. |
| | | |
| Physeal fractures involve the '''growth plate''' in all animals, and are classified according to the system described by Salter-Harris. | | Physeal fractures involve the '''growth plate''' in all animals, and are classified according to the system described by Salter-Harris. |
Line 28: |
Line 24: |
| | | |
| ==Pathophysiology== | | ==Pathophysiology== |
− | In most physeal fractures, both the hypertrophipc and germinal zones are involved and therefore all types have the potential to produce '''altered growth and limb deformities'''. | + | In most physeal fractures, both the hypertrophic and germinal zones are involved and therefore all types have the potential to produce '''altered growth and limb deformities'''. |
| | | |
| '''Compression''' of the physis is more detrimental than shearing, and this is determined partly by the shape of the growth plate. For example, the distal ulnar physis can easily become compressed. | | '''Compression''' of the physis is more detrimental than shearing, and this is determined partly by the shape of the growth plate. For example, the distal ulnar physis can easily become compressed. |