Cutting edge Orthopedics

6 • CUTTING EDGE - ORTHOPEDICS Flexion Type In contrast to extension-type supracondylar humerus fractures , flexion-type injuries typically occur from impact directly to the elbow [8]. With the arm flexed, a fall onto, or a direct blow, to the posterior elbow results in an anteriorly directed force. This causes anterior displacement (flexion) of the distal fragment (Fig. 6) [8]. In the series reviewed by Mahan and colleagues (2007), all flexion-type supracondylar injuries were caused by a fall [13]. The fall was most often from the monkey bars or a swing. However, sports and other activities were also cited [13]. Associated Injuries The most common fracture to co-occur with a supracondylar humerus fracture in most studies is an ipsilateral distal radius fracture [20–22], although one series reported approximately equal incidence of ipsilateral distal radius and ipsilateral both bone forearm fractures [23]. These frac- ture patterns represent a “floating elbow,” which is a relative indication for fixation of both inju- ries. Children who have a supracondylar humerus fracture and an ipsilateral diaphyseal forearm fracture are at substantially increased risk for compartment syndrome of the forearm and should be closely monitored [9, 24]. Development of compartment syndrome has been reported to occur in 33% of children with a displaced extension-type supracondylar humerus fracture and a con- comitant displaced forearm fracture [24]. Additionally, vascular compromise occurs in up to 20% of supracondylar humerus fractures [5, 22, 25, 26]. Most commonly, this is due to the brachial artery being stretched or bent over the fracture fragments [25, 27], particularly if the excursion of the artery is limited by the supra- trochlear branch of the brachial artery [19, 25]. However, the brachial artery may be contused, compressed, damaged by an intimal injury that could result in an aneurysm or a delayed occlusive thrombus [25, 28, 29], or partially or fully lacerated [25, 26, 29]. It is also possible for the brachial artery to be caught between the fracture fragments either at the time of the injury or during reduction maneuvers [9, 25, 30]. Brachial artery injuries most frequently occur with posterolateral displacement of the distal fragment but also take place with posteromedial displacement [26, 30]. Neurologic injuries have been noted to occur in 10–20% of children with supracondy- lar humerus fractures [5, 25]. Campbell and colleagues (1995) observed neurologic injuries in approximately 42% of children with Type III supracondylar humerus fractures [26]. In a Fig. 6: A lateral radiograph depicting a flexion- type supracondylar humerus fracture. A fall onto the posterior aspect of a flexed elbow results in flexion (anterior displacement) of the distal humeral fragment (Courtesy of Joshua M. Abzug, MD). fracture stable in ipulation, ed in the tures that be inad- re during are typi- d with the en 3 years ur off of (i.e., bed, ater typi- ost com- dominant red [ 3 , 4 ], n balance g to con- with the bow typi- he olecra- ar forces . The ten- about the ion of the [ 5 ]. In aracteris- the distal al or pos- displace- eriosteum sely, with eriosteum tures, the Type IV erior and lly deter- , 17 ]. Flexion Type In contrast to extension-type supracondylar humerus fractures, flexion-type injuries typically occur from impact directly to the elbow [ 8 ]. With the arm flexed, a fall onto, or a direct blow, to the posterior elbow results in an anteriorly directed force. This causes anterior displacement (flexion) of the distal fragment (Fig. 4.6 ) [ 8 ]. In the series reviewed by Mahan and colleagues (2007), all flexion-type supracondylar injuries were caused by a fall [ 13 ]. The fall was most often from the monkey bars or a swing. However, sports and other activities were also cited [ 13 ]. Associated Injuries The most common fracture to co-occur with a supracondylar humerus fracture in most studies is an ipsilateral distal radius fracture [ 20 – 22 ], although one series reported approximately equal incidence of ipsilateral distal radius and ipsilateral both bone forearm fractures [ 23 ]. These fracture patterns represent a “floating elbow,” which is a relative indication for fixation of both injuries. Children who have a supracondylar h merus frac- ture and an ipsilateral diaphyseal forearm fracture are at substantially increased risk for compartment syndrome of the forearm and should be closely monitored [ 9 , 24 ]. Development of compartment syndrome has been reported to occur in 33% of Fig. 4.6 A lateral radiograph depicting a flexion-type supracondylar humerus fracture. A fall onto the posterior aspect of a flexed elbow results in flexion (anterior dis- placement) of the distal humeral fragment (Courtesy of Joshua M. Abzug, MD) S.A. Russo and J.M. Abzug