![]() The fibula has two epiphyses: one proximal epiphysis and one distal (see Figures 63-1 and 63-2). 37 This epiphysis may not always be identifiable (see Figure 63-2). 19 The epiphysis of the medial malleolus fuses to the distal tibial epiphysis very early in development (4 to 5 months in large-breed dogs). 27 The growth plate is responsible for approximately 60% of longitudinal growth of the tibia. The distal tibial epiphysis interfaces with the metaphysis via two triangular convexities in the metaphysis and corresponding concavities in the epiphysis. Note that the medial malleolar epiphysis is visible in D. C–F, Craniocaudal radiograph of the distal epiphysis of the tibia (arrows) and fibula and the medial malleolar epiphysis (arrowhead): C, 2-month-old cat D, 3-month-old female Bull Terrier E, 6-month-old castrated male Australian Shepherd and F, 9-month-old spayed female Bull Terrier. A, 3-month-old female Bull Terrier B, 9-month-old castrated male Rottweiler. 13, 29, 31įigure 63-2 A–B, Distal epiphysis of tibia and fibula. 41 Premature closure of the associated growth plate may cause tibial deformity. The apophyseal growth plate normally closes relatively late in the development of the dog (>12 months in large-breed dogs). 27, 41 The apophyseal growth plate has a flat interface with the metaphysis. 16 At some point in development (between 6 and 8 months in large-breed dogs), the proximal epiphysis fuses to the tibial tuberosity epiphysis (apophysis). It has a histologically identifiable physis, although growth occurs at a slower rate than in the nearby proximal epiphyseal plate, and it does not contribute substantially to the length of the bone. 19 The tibial tuberosity is a traction epiphysis (apophysis) that forms the prominence to which the patellar ligament attaches. 27 The associated physis (growth plate) is responsible for approximately 40% of the length of the tibia. The proximal epiphysis sits on the metaphysis, and the interface between epiphysis and metaphysis contains two small concavities that help to interdigitate the epiphysis to the metaphysis. ![]() 37 The proximal epiphysis is relatively flat and forms the articular surface of the tibia. The tibia has four separate epiphyses: proximal epiphysis, tibial tuberosity epiphysis, distal epiphysis, and medial malleolar epiphysis (Figures 63-1 and 63-2). A method for radiographic measurement of the bony axis of the tibia has been described recently in dogs. ![]() Wide variation in the length and shape of the tibia and fibula is seen among breeds. The fibula serves as an attachment site for a few muscles and for collateral ligaments of the stifle and the tarsal joints. The fibula articulates with the caudolateral part of the lateral condyle of the tibia proximally, and with the tibia and the talus distally. 12 The fibula is a thin bone that contributes little to weight bearing in dogs and cats. The tibia serves as an attachment site for many muscles, including the quadriceps femoris (stifle joint extensor), the biceps femoris, and the caudal part of the sartorius (stifle joint flexor) and cranial tibial (tarsal flexor) muscles. ![]() The tibia articulates with the femur proximally, with the tarsus distally, and with the fibula on its lateral side both proximally and distally. The tibia is a long bone that is crucial for locomotive function of dogs and cats. 29 The overall prognosis following fracture of the tibia and fibula is generally good when appropriate treatment is applied. Concurrent fracture of the fibula is common, although repair of the fibula generally is not indicated unless the proximal fibula or the lateral malleolus is involved. A variety of repair methods can be applied for tibial fracture, and selection of a repair procedure depends on multiple factors, including the type and location of the fracture, the age of the animal, the presence of associated soft tissue defects and infection (particularly in open fractures), economic considerations, and the surgeon’s preference. Immediate immobilization of the crus is recommended and surgical treatment is often indicated for fracture of the tibia. Ten percent to 20% of all tibia fractures are open fractures, with the distal tibia of mature animals being the most common site of an open fracture. 5, 6, 40 A majority of tibia fractures are diaphyseal fractures. ![]() 5, 6, 40 Tibia fractures often result from trauma, and approximately 50% of tibia fractures occur in young dogs and cats. Fractures of the tibia are relatively common in dogs and cats, accounting for 10% to 20% of all fractures. ![]()
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