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21 Cards in this Set
- Front
- Back
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What type of distal humerus fracture is most common?
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Intercondylar fractures of the distal humerus are the most common fracture pattern.
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When compared to the longitudinal axis, how many degrees off is the trochlear axis? How many degrees is the trochlea rotated?
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The trochlear axis compared with the longitudinal axis is 4 to 8 degrees of valgus.
The trochlear axis is 3 to 8 degrees externally rotated. |
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Where does the intramedullary canal of the humerus end?
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The intramedullary canal ends 2 to 3 cm above the olecranon fossa.
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What is the most common mechanism of injury for distal humerus fractures?
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Most low-energy distal humeral fractures result from a simple fall in middle-aged and elderly women in which the elbow is either struck directly or is axially loaded in a fall onto the outstretched hand.
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Which neurovascular structures are at risk in a distal humerus fracture?
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A careful neurovascular evaluation is essential because the sharp, fractured end of the proximal fragment may impale or contuse the brachial artery, median nerve, or radial nerve.
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How far does the lateral epicondyle of the distal humerus jut from the line of the shaft?
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The articular segment juts forward from the line of the shaft at 40 degrees and functions architecturally as the tie arch at the point of maximum column divergence distally.
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What could be an outcome of increased swelling of the distal humerus following a fracture?
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Serial neurovascular examinations with compartment pressure monitoring may be necessary with massive swelling; cubital fossa swelling may result in vascular impairment or the development of a volar compartment syndrome resulting in Volkmann ischemia.
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What type of radiographs beyond AP and laterals would be helpful for preoperative planning?
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Traction radiographs may better delineate the fracture pattern and may be useful for preoperative planning.
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What might change on a lateral radiograph with a non-displaced fracture of the distal humerus?
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Minimally displaced fractures may result in a decrease in the normal condylar shaft angle of 40 degrees seen on the lateral radiograph.
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How does one nonoperatively treat an extension-type supracondylar humerus fracture that is non-displaced?
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Posterior long arm splint is placed in at least 90 degrees of elbow flexion if swelling and neurovascular status permit, with the forearm in neutral.
Posterior splint immobilization is continued for 1 to 2 weeks, after which range-of-motion exercises are initiated. The splint may be discontinued after approximately 6 weeks, when radiographic evidence of healing is present. |
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How much of a change in the condylar angle relative to the shaft may be tolerated?
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Up to a 20-degree decrease in the condylar-shaft angle may be tolerated owing to compensatory motion of the shoulder.
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How are flexion type supracondylar humerus fractures treated nonoperatively?
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Nondisplaced or minimally displaced fractures may be immobilized in a posterior elbow splint in relative extension. Elbow flexion may result in fracture displacement.
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Which muscles tend to displace the lateral and medial epicondyles in an intercondylar distal humerus fracture?
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Medial epicondyle - flexor mass
Lateral epicondyle - extensor mass |
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What tends to be the mechanism of injury with a intercondylar distal humerus fracture?
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Force is directed against the posterior aspect of an elbow flexed >90 degrees, thus driving the ulna into the trochlea.
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What is the classification system for intercondylar humerus fractures?
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RISEBOROUGH AND RADIN
Type I: Nondisplaced Type II: Slight displacement with no rotation between the condylar fragments Type III: Displacement with rotation Type IV: Severe comminution of the articular surface |
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What are the typical mechanisms of injury in patients with condylar fractures?
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Abduction or adduction of the forearm with elbow extension.
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What is the classification system of condylar fractures?
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MILCH
Two types are designated for medial and lateral condylar fractures; the key is the lateral trochlear ridge : Type I: Lateral trochlear ridge left intact Type II: Lateral trochlear ridge part of the condylar fragment (medial or lateral) |
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In a Milch Type II fracture, what is a possible complication?
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They may allow for radioulnar translocation if capsuloligamentous disruption occurs on the contralateral side.
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How is a condylar fracture treated nonoperatively?
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It consists of posterior splinting with the elbow flexed to 90 degrees and the forearm in supination or pronation for lateral or medial condylar fractures, respectively.
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What is the classification system for capitellum fractures?
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Type I: Hahn-Steinthal fragment: large osseous component of capitellum, sometimes with trochlear involvement
Type II: Kocher-Lorenz fragment: articular cartilage with minimal subchondral bone attached: "uncapping of the condyleâ" Type III: Markedly comminuted |
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What ligament is a fibrous arch connecting the supracondylar process with the medial epicondyle, from which fibers of the pronator teres or the coracobrachialis may arise.
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The ligament of Struthers
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