Page 1572 - Clinical Small Animal Internal Medicine

1510 Section 13 Diseases of Bone and Joint

Table 171.1 Epiphyseal growth center appearance and growth plate fusion of selected bones in immature dogs
VetBooks.ir Anatomic site Age when ossification center appears Age when fusion occurs

Humerus Diaphysis Birth
Proximal epiphysis 1–2 wk 10–13 mo
Distal epiphysis 6–8 mo to shaft
Medial condyle 2–3 wk 6 wk to lateral condyle
Lateral condyle 2–3 wk
Medial epicondyle 6–8 wk 6 mo to condyle
Radius Diaphysis Birth
Proximal epiphysis 3–5 wk 6–11 mo
Distal epiphysis 2–4 wk 8–12 mo
Ulna Diaphysis Birth
Olecranon 8 wk 6–10 mo
Distal epiphysis 8 wk 8–12 mo
Femur Diaphysis Birth
Proximal epiphysis (head) 2 wk 7–11 mo
Trochanter major 8 wk 6–10 mo
Trochanter minor 8 wk 8–13 mo
Distal epiphysis 8–11 mo to shaft
Trochlea 2 wk 3 mo condyle to trochlea
Medial condyle 3 wk
Lateral condyle 3 wk
Tibia Diaphysis Birth
Medial condyle 3 wk 6 wk to lateral
Lateral condyle 3 wk 6–12 mo to shaft
Tuberosity 8 wk 6–8 mo to condyle
6–12 mo to shaft
Distal epiphysis 3 wk 8–11 mo
Medial malleolus 3 mo 5 mo
Fibula Diaphysis Birth
Proximal epiphysis 9 wk 8–12 mo
Distal epiphysis 2–7 wk 7–11 mo
Tarsus Talus Birth–1 wk
Fibular Birth–1 wk

Source: Modified from Owens JM. Radiographic Interpretation for the Small Animal Clinician. St Louis, MO: Ralston Purina Company, 1982, and
Ticer JW. Radiographic Technique in Small Animal Practice. Philadelphia, PA: Saunders, 1975.

Growth‐Plate Associated Growth
bone. At about the same time – albeit with a different
Growth plates facilitate bone length growth by the circadian rhythm – growth plate cartilage is converted
formation of new cartilage. The volume increase of into bone at the junction of the growth plate and the
cartilage in a growth plate is a function of chondrocyte metaphysis via EO. Because the rate of bone length
proliferation, chondrocyte enlargement, and matrix growth and the rate of advancement of the EO minerali-
formation. Because growth in width of a growth plate is zation from the metaphysis are approximately the same,
constrained, the newly formed cartilage pushes the epi- the thickness of a growth plate will not vary much from
physis away from the metaphysis, thus elongating the day to day.