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CHAPTER 19 • Clavicle and Scapula Fractures and Acromioclavicular and Sternoclavicular Injuries

joint should be palpated, as a posteriorly displaced proximal fragment may be felt entrapped in the trapezius muscle, and is critical to treatment decision-making. In addition, palpation of the entire upper extremity, hemithorax, and cervical spine should be performed to identify the location of maximal tender- ness as well as additional areas that may have sustained a con- comitant injury. A complete neurovascular examination should be performed to evaluate for rare brachial plexus injury. Patients involved in high-energy mechanisms should have a complete head-to-toe survey performed by the orthopedic physician as well as either a member of the trauma team or the emergency room physician. Initial imaging should be performed by obtaining plain radio- graphs of the shoulder including a true AP view and a cephalic tilt view, which may be performed most commonly with a 15-degree cephalic or 45-degree cephalic tilt. 163 Due to the significance of assessing posterior displacement of the medial fragment relative to the acromion or distal fragment, the axil- lary lateral view is of critical importance, and should be pur- sued, even if it requires assistance from a member of the clinical team, with gentle, gradual abduction of the arm to facilitate a clear view of the shoulder. A CT scan may be diagnostic for intra-articular fractures, which may require operative interven- tion for best results, and can be helpful to assess the precise degree and direction of the displaced medial fragment, the posi- tion of which will determine the need for surgery when phys- ical examination and the axillary view do not allow for a clear assessment. CLASSIFICATION OF DISTAL CLAVICLE FRACTURES The most commonly used classification scheme for distal clavicle fractures is that proposed by Neer and modified by Craig. 33,110 This classification scheme includes five types based on the relationship of the fracture line to the CC ligaments, the AC ligaments, and the physis. Most lateral clavicle fractures in the skeletally immature patients are periosteal disruptions in which the bone displaces away from the periosteal sleeve whereas the CC ligaments remain attached to the intact inferior portion of the periosteum. Type I fractures occur distal to the CC ligaments but do not involve the AC joint. Minimal displacement occurs due to the proximal fragment being stabilized by the intact CC ligaments and the distal fragment being stabilized by the AC joint capsule, the AC ligaments, and the deltotrapezial fascia. Type II fractures are subdivided into type IIA and type IIB fractures, with type IIA fractures occurring medial to the CC ligaments and type IIB fractures occurring between the CC ligaments with concomitant injury to the conoid ligament. In type IIA injuries, the proximal fragment loses the stability pro- vided by the CC ligaments and displaces superiorly out of the periosteal sleeve. In contrast, the distal fragment remains stable because of the attachments of the AC joint capsule, AC liga- ments, and the CC ligament(s). This remains true for type IIB IMAGING AND OTHER DIAGNOSTIC STUDIES FOR DISTAL CLAVICLE FRACTURES

fractures as well, because even though the conoid ligament is disrupted, the trapezoid ligament remains attached. Type III fractures occur distal to the CC ligaments and extend into the AC joint. As these fractures do not disrupt the ligamen- tous structures, minimal displacement is the norm. Type IV fractures occur in skeletally immature patients and involve a fracture medial to the physis. The epiphysis and physis remain uninjured and attached to the AC joint. However, signif- icant displacement can occur between the physis and metaph- yseal fragment, as the CC ligaments are attached to the physis. This is especially true if the periosteal sleeve is disrupted. In essence, this is analogous to a type IIA fracture. Type V fractures have a fracture line that leaves a free-floating inferior cortical fragment attached to the CC ligaments with an additional fracture line dividing the distal clavicle from the remainder of the clavicle. Therefore, neither the proximal nor distal fragment is attached to the CC ligaments. The end result is instability with the potential for significant displacement of the distal end of the proximal fragment. No outcome measures have been specifically applied to pedi- atric distal clavicle fractures. Commonly utilized measures for adult distal clavicle fractures include the ASES score, the DASH Score, the QuickDASH, and the Constant Shoulder Score. The recent publication of a novel Pedi-ASES demon- strated that adult shoulder outcome scores such as the DASH and ASES surveys are associated with poor validity and com- prehensibility in pediatric populations, and this new met- ric, when more comprehensively validated, may emerge as a future standard for use in pediatric and adolescent shoulder research. 60 OUTCOME MEASURES FOR DISTAL CLAVICLE FRACTURES The distal aspect of the clavicle forms the articulation with the scapula via the AC joint. Ligamentous connections between this portion of the clavicle and the scapula include the AC lig- aments and CC ligaments. The CC ligaments include the trap- ezoid ligament, located more laterally with an attachment to the distal clavicle approximately 2 cm from the AC joint, and the conoid ligament, located more medially with an attach- ment to the distal clavicle approximately 4 cm from the AC joint. 126 The presence of these ligamentous attachments and the acromioclavicular joint capsule permits fluid scapulotho- racic motion. 11 Stability of the clavicle in the horizontal/AP plane is provided by the AC ligaments, whereas stability in the vertical/superoin- ferior plane is provided by the CC ligaments. 45 This stability permits the definition of the CC space, the space between the coracoid process and the undersurface of the clavicle, which should be 1.1 to 1.3 cm. 16 PATHOANATOMY AND APPLIED ANATOMY RELATED TO DISTAL CLAVICLE FRACTURES