Cutting edge Orthopedics

2 • CUTTING EDGE - ORTHOPEDICS 6 or 7 years of age, which may make the cortex even thinner during that timeframe [6]. Given these factors, the supracondylar humerus is at a relatively high risk for fracture [5, 6, 8, 9]. Although supracondylar humerus fractures occur in the metaphyseal region with the most common deformity (extension) in the plane of motion of the elbow joint [10], they have little remodeling potential [11]. This is due to the relatively small longitudinal growth of the distal humerus [11]. It contributes only approximately 20% of the growth of the humerus, while the proximal humerus accounts for the majority of longitudinal growth, at roughly 80% [5, 9, 12]. Classification Supracondylar humerus fractures are characterized as extension or flexion types depending on the direction of displacement of the distal fragment. Flexion-type injuries are uncommon, as approximately 97–99% of supracondylar humerus fractures are extension type [3, 13]. Extension-type supracondylar humerus fractures are typically classified using the modified Gartland classification system [5, 14–16]. The original Gartland classification described three extension-type injuries [15], and a fourth type has been proposed more recently (Table 1) [17]. Type I fractures are nondisplaced (Fig. 2) or minimally displaced (<2 mm) with an intact ante- rior humeral line (described in the "Radiographic Evaluation" section). Type II fractures main- tain an intact posterior hinge of periosteum but demonstrate extension of the distal fragment. Wilkins (1984) divided Type II fractures into two subtypes: Type IIA fractures (Fig. 3) have no rotational deformity, while Type IIB fractures (Fig. 4) exhibit rotational deformity despite the intact posterior hinge [16]. While this distinction aids in determination of appropriate treatment, low interrater reliability has been reported for differentiation between Type IIA and IIB frac- tures [18]. Type III fractures are characterized by complete displacement with no cortical contact (Fig. 5). They commonly demonstrate rotational deformity. The Type IV fracture is described as a Fig. 1: The thin bone in between the coronoid fossa (anterior) and olecranon fossa (posterior) is readily visualized in a lateral view of the distal humerus (Courtesy of Shriners Hospitals for Children, Philadelphia). mately 20% of the growth of the humerus, while the proximal humerus accounts for the majority of longitudinal growth, at roughly 80% [ 5 , 9 , 12 ]. fractures are extension type [ 3 , 13 ]. Extension-type supracondylar humerus frac- tures are typically classified using the modified Gartland classification system [ 5 , 14 – 16 ]. The original Gartland classification described three extension-type injuries [ 15 ], and a fourth type has been proposed more recently (Table 4.1 ) [ 17 ]. Type I fractures are nondisplaced (Fig. 4.2 ) or minimally displaced (<2 mm) with an intact ante- rior humeral line (described in the Radiographic Evaluation section). Type II fractures maintain an intact posterior hinge of periosteum but demon- strate extension of the distal fragment. Wilkins (1984) divided Type II fractures into two sub- types: Type IIA fractures (Fig. 4.3 ) have no rota- tional deformity, while Type IIB fractures (Fig. 4.4 ) exhibit rotational deformity despite the intact posterior hinge [ 16 ]. While this distinction aids in determination of appropriate treatment, low interrater reliability has been reported for differentiation between Type IIA and IIB frac- tures [ 18 ]. Type III fractures are characterized by complete displacement with no cortical con- ta t (Fig. 4.5 ). They commonly d monstrate rotational deformity. The Type IV fracture is Fig. 4.1 The thin bone in between the coronoid fossa (anterior) and olecranon fossa (posterior) is readily visual- ized in a lateral view of the distal humerus (Courtesy of Shriners Hospital for Children, Philadelphia) Table 4.1 Radiographic findings, fracture characteristics, and typical anagement recommendations for each exten- sion fracture type of the modified Gartland classification Fracture type Radiographic findings Stability Treatment recommendations I Minimal displacement, AHL intersects center of capitellum Stable Immobilization in long arm cast for 3 weeks II IIa Posterior cortex intact, AHL anterior to capitellum Stable Closed reduction and pinning in most cases, some may be treated like Type I IIb Posterior cortex intact, rotational deformity, AHL anterior to capitellum Rotational instability Closed reduction and pinning III No cortical contact, AHL anterior to capitellum Unstable in extension Closed reduction and pinning IV Typically no cortical contact, AHL anterior or posterior to capitellum Unstable in flexion and extension Closed reduction and pinning AHL anterior humeral line