Rockwood, Green, and Wilkins' Fractures, 10e Package

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SECTION ONE • General Principles

Diaphyseal (Fig. 5-8) For diaphyseal fractures, the morphology is defined as follows: Type A: Simple-one fracture line of at least 90% of the circum ference of bone. This can include spiral, oblique, and trans verse fracture lines. Type B: Wedge-fractures characterized by contact between the main fragments after reduction, which usually restores the normal length of bone. The wedge may be intact or in mul tiple fragments (i.e., Fragmentary wedge). Type C: Multifragmentary fractures that are characterized by many fracture lines and fracture fragments. As introduced above the term “complex” was replaced in the 2018 com pendium update by the term “multifragmentary,” which in the diaphysis implies that even after reduction, if fracture fragments were removed, bone-to-bone contact in the diaph ysis would not exist. End Segment (Fig. 5-9) The morphology of the end segment is described based on the level of articular involvement. Type A: Extra-articular. There are no fracture lines that enter the articular surface (see Fig. 5-7). Type B: Partial articular. The fracture involves only part of the articular surface, and the remainder of the joint is intact and connected to the supporting end segment. Type C: Complete articular. The fracture or fractures disrupt the articular surface such that the articular surface is com pletely separated from the diaphysis. The process of classification and coding of an individual fracture based on the OTA/AO classification scheme then fol lows the format in Tables 5-1 and 5-2. The 2018 Compen dium includes added Universal Modifiers and Qualifications (Table 5-3), which capture additional useful information when added to the end of the fracture-specific codes. SELECTED RECENT STUDIES ON THE OTA/AO 2018 FRACTURE COMPENDIUM CLASSIFICATION Studies of the 2018 OTA/AO classification are gradually being published. Beebe et al. reviewed 2,885 open fractures of the tibia and noted that the OTA/AO classification was highly pre dictive of compartment syndrome. 66 From their patient pop ulation, OTA/AO 41-C injuries were 5.5 times more likely to advance to acute compartment syndrome (ACS) compared with OTA/AO 41-As; conversely, OTA/AO 43 injuries were at least 4.0 times less likely to progress to ACS. 4 Marmor et al. compared the Neer classification with the 2018 classification by giving x-rays and CT scans to seven inde pendent raters. 35 They found that all raters graded the OTA/AO classification as “good or better than the Neer classification for an adequate description of the fracture pattern.” 35 The full-form of the OTA/AO classification was superior for characterizing specific fracture types. 35 Nonetheless, they noted that the “low inter-rater reliability of the full 2018 OTA/AO classification is a concern that needs to be addressed in the future.” 35

lies between the two squares or end segments. The parts of bones are numbered as follows: the proximal end segment is 1, the diaphyseal segment is 2, and the distal end segment is 3. The location of the fracture can be found by identifying the center. In a simple fracture, the center is intuitive; in a wedge fracture, the center is at the level of the broadest part of the wedge; and in a multifragmentary wedge, the center can only be determined after reduction. The segment of a long bone (proximal—1, diaphyseal—2, distal—3) that contains the cen ter of the fracture is then assigned the appropriate numerical code. Any diaphyseal fracture that includes a displaced articular component is considered an articular fracture. If a single bone has multiple fractures, each fracture is classified separately. The description of the morphology of fractures depends on whether it is a diaphyseal or an end-segment fracture. Figure 5-6. The OTA/AO classification of fractures requires identifica tion of which bone is fractured according to an alphanumeric scheme. (Reprinted with permission from Meinberg E, et al. Fracture and dis location classification compendium—2018 International Comprehen sive Classification of Fractures and Dislocations Committee. J Orthop Trauma . 2018;32(1 Suppl):S1–S10. Copyright © 2018 by AO Foun dation, Davos, Switzerland; Orthopaedic Trauma Association, IL, US.)