Metaphyseal Fractures

The classification system of Salter and Harris which separates fractures into five main types is most widely used (Salter and Harris 1963) (Fig. 10.5). Other fracture types have since been added to the original classification (Ogden 1981 Rang 1983). In a further classification Peterson added additional categories (Peterson et al. 1994) while including type I to IV Salter Harris injuries, type V is deleted and two new types of fractures metaphyseal fractures with linear injuries that pass into the growth plate, and major trauma that results in destruction of part of the physis. 

At the microscopic level, bone consists of two structures woven and lamellar (Fig. la). Woven bone (with an average mineral grain size of 10 to 50 nm) is the immature, or primitive, form of bone and is normally found in the metaphyseal region of growing bone as well as in fracture callus (Kaplan et al., 1994 Park and Lakes, 1992). Woven bone is coarse-fibered and... 

OI type V is now widely recognized as a distinct OI phenotype with characteristic clinical and radiological features, such as predisposition to formation of hypertrophic callus at sites of fractures or surgical interventions, early calcification of the interosseous membrane of the forearm, and appearance of dense metaphyseal bands in radiographs. Patients have moderate... 

Stmctural load-bearing applications of bone grafts cannot be performed by injection but in situ setting bone graft substitutes can be injected to provide structural support or fixation for metaphyseal and epiphyseal fractures. 

Metaphyseal corner fractures are highly associated with non-accidental trauma and it is important not to confuse certain normal metaphyseal variants with these injuries. The normal metaphyseal variants include metaphyseal step-off, beak or spur, and proximal tibial cortical irregularity (Kleinman et al. 1991). All of these variants may be unilateral or bilateral. It is important to be familiar with their appearances in order that they are not mistaken for signs of abuse, with often devastating consequences. A metaphyseal step off is an acute, near 90 degree angulation in the extreme portion of the metaphysis adjacent to the physis (Fig. 7.68). The adjacent corti-... 

Midshaft diaphyseal fractures of the forearm unite more slowly than diaphyseal injuries. Nevertheless, most fractures will be solid by 6 weeks. Whilst the presence of periosteal callus around metaphyseal fractures usually indicates that the bone will be stable, this is not the case with midshaft injuries. Here, the bones may still move within the cast... 

Transverse fractures result from direct blows. Twisting injuries produce the more common spiral fracture. In infants, this injury should always rouse suspicion of child abuse. The position of the bony fragments will be determined by the pull of adjacent muscles. For proximal metaphyseal fractures, the rotator cuff abducts the proximal fragment while the distal fragment is adducted by the pectoralis muscle. 

Fig. 10.10. a AP radiograph of the left knee showing metaphyseal fracture of both the distal femur and proximal tibia, b Lateral radiograph of the same patient shows periosteal reaction around the proximal tibia due to healing... 

Due to the child s more flexible skeleton and increased amount of stretch allowed by the soft tissues, the majority of childhood fractures are undisplaced. Greater strength of the joint capsule and ligaments compared with the metaphyseal bone also means that fractures occur much more readily than dislocations. In the infant, hard tissues (cartilage and bone) may be considered as soft, while soft tissues (tendons and ligaments) should be considered as hard. 

Fig. 11.2. Metaphyseal fractures. AP view of a knee shows the two typical appearances of corner fractures arrows) and a bucket handle fracture arrowhead)...

Kleinman and co-workers have thrown new light on this classic metaphyseal lesion (CML) associated with abuse (Kleinman et al. 1986 Kleinman and Marks 1995,1996,1998). They have shown that the fundamental abnormality is a complete or incomplete transmetaphyseal fracture through the most immature metaphyseal primary spongiosa. Furthermore, as the fracture line passes peripherally towards the cortex it deviates away from the physis to undercut a thicker peripheral segment that encompasses the subperiosteal bone collar (Fig. 11.3). 

As Caffey originally pointed out, metaphyseal fractures are the result of tractional and torsional forces applied to a limb. This can occur when a limb is used as a handle or when centrifugal forces act during violent shaking. Rarely, an isolated metaphyseal fracture maybe found and correlated with a plausible accidental event. However, in all other circumstances this injury in an otherwise normal child is virtually diagnostic of non-accidental injury. 

Fig. 11.4a,b. Healing of a metaphyseal fracture without the typical changes of a healing fracture, a Acute metaphyseal fracture. b Follow-up film with no evidence of callus or subperiosteal new hone formation... 

Fig. 11.5. A healed metaphyseal fracture, but with focal scalloping of its epiphyseal margin...

Fresh fractures, including metaphyseal fractures, have sharply defined margins. With the development of an osteoclastic response to necrotic bone, the fracture ends become less well defined and the fracture widens. There are no objective criteria to estimate fracture healing using this sign but it is not apparent radiologically before 10 days and reaches a peak at 2-3 weeks. 

Condition Shaft fractures SNBF Metaphyseal abnormalities Osteopenia Comments... 

Anderson WA (1982) The significance of femoral fractures in children. Ann Emerg Med 11 174-177 Anilkumar A, Fender LJ, Broderick NJ et al (2006) The role of the follow-up chest radiograph in suspected non-accidental injury. Pediatr Radiol 36 216-218 AstleyR (1979) Metaphyseal fractures in osteogenesis imperfecta. Br J Radiol 52 441-443... 

SH 11 is the commonest fracture pattern with the metaphyseal fragment often on the lateral (compression) side, due to a valgus force (Fig. 14.5). A direct anterior force will cause a hyperextension injury where the distal epiphysis is displaced anteriorly... 

SH II injuries are associated with subsequent growth disturbance usually on the contralateral side to the metaphyseal fracture, as this is the point of maximal injury of the physis. 

---