1887

The humerus

image of The humerus
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Abstract

The humerus lies within the brachium, articulating proximally with the scapular glenoid to form the shoulder joint and distally with the radius and ulna to form the elbow joint. This chapter looks at humeral diaphyseal fractures, fractures of the distal humerus. Salter-Harris type I and II fractures of the proximal humerus; Salter-Harris type III fractures of the proximal humerus; Medial approach to the humeral diaphysis for bone plate application; Medial approach to the distal humerus for bone plate application; Lateral approach to the humeral diaphysis for bone plate application; Lateral approach to the distal humerus for bone plate application; Lateral condylar fractures; Medial condylar fractures; Intracondylar Y-T fractures; Intramedullary pinning; Pin-plate application; Linear external skeletal fixation of the humerus; Supracondylar humeral fractures; Placement of a medial to lateral transcondylar positional cortical bone screw for humeral intracondylar fissure.

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Figures

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20.1 (a) Salter–Harris type I and (b) Salter–Harris type III separation of the proximal humeral epiphysis. Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
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20.2 (a) Short oblique diaphyseal humeral fracture in a 3-year-old Cavalier King Charles Spaniel. (b) The humeral diaphysis has been anatomically reconstructed using a 1.5 mm lag screw. A veterinary cuttable plate has been applied to the medial aspect of the humerus. Minimal contouring of the bone plate was required.
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20.3 (a) Comminuted grade 2 open humeral fracture in an 11-year old Staffordshire Bull Terrier. (b) Mediolateral and (c) craniocaudal radiographs showing that the large cranial fragment has been anatomically reduced and stabilized using two 2.7 mm lag screws. The humeral diaphysis was then anatomically reduced and stabilized using orthogonal bone plates – a lateral 2.7 mm locking compression plate (LCP) and a cranial 2.7 mm dynamic compression plate (DCP). The proximal humerus would have readily accommodated a 3.5 mm bone plate and screws, however the narrower lateral supracondylar ridge would not, hence the 2.7 mm plates were used. Although the fracture had been anatomically reconstructed the lateral LCP in isolation was not considered mechanically robust enough given both the poor biology and high mechanical challenge that this fracture presented. Note how the supratrochlear foramen limits the distal extent of cranial plate application.
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20.4 (a) Comminuted humeral diaphyseal fracture in a 4-year-old Springer Spaniel. (b) This fracture is non-reconstructable and has been managed using a bridging osteosynthesis technique comprising a type 1a ESF construct and an IM pin. Allogenic cancellous bone chips were placed at the fracture site.
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20.5 (a) Craniocaudal and (b) mediolateral radiographs showing a mid-diaphyseal humeral fracture stabilized using a pin–plate technique. The IM pin has been seated into the medial aspect of the distal humerus and the bone plate placed on the lateral aspect of the humerus. (Courtesy of J Pink)
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20.6 The distal humerus in the dog. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
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20.7 The feline humerus. Note the presence of the supracondylar foramen at the distal extent of the medal supracondylar ridge, through which the median nerve and brachial artery pass. Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
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20.8 (a) Craniocaudal and (b) mediolateral radiographs of a supracondylar fracture in a 4-month-old Cocker Spaniel, which has been stabilized using an IM pin and a type 1a external skeletal fixator. Note the distal position of the IM pin and the use of the humeral condyle for the most distal external fixator pin. (c) The IM pin has been ‘tied in’ to the external skeletal fixator.
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20.9 (a) Craniocaudal and (b) mediolateral radiographs showing a supracondylar humeral fracture in a 6-month-old Springer Spaniel which has been stabilized using bilateral bone plate application. A 2.7 mm locking compression plate (LCP) has been placed medially and a 2.0/2.7 mm veterinary cuttable plate laterally. In this case the use of non-locking screws with the medial LCP allows for more variation in direction of screw orientation, which can be helpful when placing plate screws in the distal humerus.
Image of 20.10
20.10 (a) A craniocaudal radiograph of the elbow showing a sagittal fissure (arrow) within the humeral condyle running from its proximal to distal aspect. Remodelling of the lateral supracondylar ridge (star) is also apparent. (b) The intracondylar fissure is also evident on a transverse CT image. Note the condylar sclerosis immediately adjacent to the fissure.
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20.11 A dorsal plane CT image of the distal humerus in a 9-week-old Cavalier King Charles Spaniel. Note the normal intracondylar physis separating the trochlea (T) and the capitulum (C).
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20.12 A transcondylar shaft screw has been placed for HIF repair. (Courtesy of A Moores)
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20.13 Medial to lateral positional transcondylar screw placement for HIF repair.
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20.14 Salter–Harris type III fracture of the humeral condyle in a 9-week-old crossbreed dog. There is fracture and mild displacement of the medial aspect of the epiphysis of the humeral condyle.
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20.15 Fracture of the lateral portion of the humeral condyle in a 3-year-old Springer Spaniel. (a) The craniocaudal view shows proximal displacement of the lateral humeral condyle and the antebrachium. (b) In this patient, displacement of the fracture is also apparent on the mediolateral view, although less so than on the orthogonal view. It should be noted that fracture displacement is often less readily apparent on the mediolateral view, particularly in skeletally immature patients, and can be missed if an orthogonal view is not obtained.
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20.16 Medial humeral condylar fracture in a 5-month-old Labrador Retriever. (a) As with lateral condylar fractures, displacement of the fracture is most evident on the craniocaudal view. (b) Displacement is less readily apparent on the mediolateral view.
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20.17 (a) The lateral condylar fracture shown in Figure 20.15 has been anatomically reconstructed and stabilized using a transcondylar lag screw and a 5-hole 2.7 mm string-of-pearls plate and screws. (b) In skeletally immature patients with no pre-existing intracondylar pathology, a K-wire can be used to stabilize the lateral supracondylar ridge fracture; however, this is less robust than plate fixation.
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20.18 (a) ‘T’ and (b) ‘Y’ dicondylar humeral fractures.
Image of 20.19
20.19 (a) Three-dimensional CT image of a dicondylar humeral fracture in a 5-year-old Springer Spaniel. (b) Craniocaudal and (c) mediolateral radiographs showing that the fracture has been stabilized using a transcondylar lag screw and bilateral 2.7 mm locking compression plates using both locking and non-locking screws. Note the degree of lateral plate contouring that was required in comparison to the medial plate.
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20.20 (a) Dicondylar fracture with severe comminution of the supracondylar region in a cat. (b) Linear/circular ESF has been used to stabilize the fracture. The articular surface has been anatomically reconstructed and the humeral condyle stabilized using two olive wires placed in opposite orientations to achieve interfragmentary compression. (Courtesy of D Clements)
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20.21 Reduction of a Salter–Harris type I/II fracture.
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20.22 Salter–Harris type I/II fractures of the proximal humerus: methods of fixation.
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20.23 Salter–Harris type III fractures of the proximal humerus: method of fixation.
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20.24 Medial approach to the humerus for the application of a plate.
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20.25 (a–c) Craniolateral approach for application of a plate to the cranial aspect of the humeral shaft. (d) Lateral view of the plate in place.
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20.26 (a) Additional exposure for application of a plate to the lateral side of the humerus. (b) Lateral view of the plate in place.
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20.27 Surgical approach for exposure of lateral condylar fractures.
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20.28 (a) The lateral portion of the humeral condyle is rotated out laterally on its collateral ligament to allow inspection of the fracture site and removal of the fracture haematoma. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission. (b–d) Methods of maintaining reduction of lateral condylar fractures during transcondylar screw placement.
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20.29 Lag screw fixation of lateral condylar fractures (see text for details). In many cases, the epicondylar ridge is fractured more distally, necessitating placement of the K-wire in a distolateral to proximomedial direction. Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
Image of 20.30
20.30 ‘Inside-out’ placement of a transcondylar lag screw (see text for details). The K-wire must cross the epicondylar fracture line but must not enter the supratrochlear foramen. Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
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20.31 Placement of a transcondylar screw for the fixation of a medial condylar fracture using the ‘outside-in’ method. (a) The green line highlights the medial epicondylar ridge; the drill bit should be positioned so that it is parallel to the epicondylar axis. (b) The black circles mark the proximal and distal extent of the medial epicondylar ridge. The red circle marks the entry point. The appropriate start point for transcondylar screw placement is immediately cranial to the medial epicondylar ridge and approximately halfway between its proximal and distal aspect. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 20.32
20.32 Reduction and fixation of a dicondylar fracture by humeral condyle reconstruction and stabilization followed by reattachment of the intact humeral condyle on to the humeral shaft. (a–c) Once it is ascertained that the condyle can be reduced, it is stabilized with a transcondylar lag screw. (d–e) The humeral condyle is then reduced on to the humeral shaft. In this example, a K-wire has been placed to maintain reduction, after which bone plates are placed on the lateral and medial aspects of the distal humerus (see text for details). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 20.33
20.33 Reduction and fixation of a dicondylar fracture by reduction and reattachment of either the medial or lateral humeral condyle on to the humeral shaft followed by repair of the resultant unicondylar fracture. (a–b) The medial humeral condyle is anatomically reduced and stabilized using a bone plate. (c) Subsequently the lateral condylar fracture is repaired using a transcondylar lag screw and bone plate (see text for details). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 20.34
20.34 An oblique humeral fracture in a 4-month-old kitten has been stabilized using an IM pin and cerclage wire. Note how the IM pin occupies all of the narrowest part of the medullary canal. When using a pin this size it has to be seated proximal to the supratrochlear fossa in the cat and the supratrochlear foramen in the dog.
Image of 20.35
20.35 IM pin placement for humeral fractures. (a) For more distal fractures, a smaller pin is used which is placed into the medial epicondyle. (b) For more proximal fractures, a larger pin is used which is seated distally immediately proximal to the supratrochlear foramen. Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
Image of 20.36
20.36 (a) Distal aspect of the canine humeral condyle. The distal entry point for normograde pin placement is on the distal aspect of the caudal part of the medial epicondyle (arrowed) ( ). (b) Distal aspect of the feline humeral condyle. The distal entry hole is pre-drilled, starting immediately medial to the humeral trochlea and cranial to the caudal cortex of the medial epicondyle (arrowed) ( ). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
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20.37 Areas suitable for ESF pin placement in the canine humerus ( ). Similar areas are present in the feline humerus ( ). Drawn by Vicki Martin Design, Cambridge, UK and reproduced with her permission.
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20.38 External skeletal fixator placement in combination with an IM pin (see text for details). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 20.39
20.39 Stabilization of a supracondylar fracture using an IM pin and K-wire. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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