Chapter 96 - Radius and Ulna Flashcards
Classification scheme for ulnar fractures. Type 1a, fracture along the apophyseal physis;
Type 1b Articular, fracture starting out along the apophyseal physis and then breaking into the metaphyseal part of olecranon process and finally entering the elbow joint;
Type 1b Nonarticular, fracture starting out along the apophyseal physis and breaking out the cranial cortex of the olecranon proximal to the anconeal process;
Type 2, simple fracture through the body of the olecranon with articular involvement;
Type 3, simple fracture through the body of the olecranon without articular involvement;
Type 4, multifragment fracture of the olecranon with or without articular involvement;
Type 5, distal oblique ulnar fracture with marginal articular involvement.
What comprises the equine antebrachium?
Radius and Ulna
Which bone in the antebrachium is the major weight-supporting bone?
Radius
What is the primary function of the olecranon?
Acts as a lever arm during elbow and carpal extension
How common are fractures of the ulna in horses?
Relatively common
What is the treatment of choice for fractures of the ulna in horses?
Fracture fixation using a bone plate as a tension band
What is the structure of the ulna in horses?
Triangular in cross-section and tapers distally
What is the olecranon in relation to the ulna?
The proximal part of the ulna
What can result from disturbances in the growth of the olecranon physis?
Development of elbow dysplasia
What is the most common cause of fractures of the ulna in horses?
Direct blow from a kick or fall
Where do fractures often occur when a foal rears up and falls?
The body of the ulna or the olecranon
What is a common fracture type in horses less than one year of age?
A. Type 1b fracture
B. Type 2 fracture
C. Type 3 fracture
D. Type 5 fracture
A. Type 1b fracture
What is the most common fracture configuration in neonates?
A. Physeal separations (type 1a)
B. Transverse fractures (type 2)
C. Nonarticular, nonphyseal fractures (type 3)
D. Comminuted fractures (type 4)
Physeal separations (type 1a)
What kind of fractures are encountered commonly in horses over one year of age?
Distal olecranon-proximal ulnar body fractures
What is a typical presentation of a horse with nondisplaced olecranon fractures?
Dropped elbow and lameness is the primary complaint
What type of radiograph is necessary for complete visualization of the cubital joint and proximal olecranon?
Medial to lateral projection
Which diagnostic tool is occasionally indicated to determine communication between a soft tissue wound and the cubital joint?
Contrast arthrogram
What indicates the severity of soft tissue injury accompanying an olecranon fracture?
A. Degree of lameness
B. Size of the wound
C. Displacement of the fracture
D. Swelling in the humeral region
C. Displacement of the fracture
What is the first step in the initial care for horses with a fractured ulna accompanied by a wound?
Wound therapy with hair removal at the wound margins
What may be used in extensive soft tissue wounds to reduce bacterial numbers?
A. Antibiotic ointments
B. Sterile saline solution
C. Antimicrobial-impregnated PMMA beads
D. Anti-inflammatory drugs
C. Antimicrobial-impregnated PMMA beads
What is a common problem in horses with displaced fractures?
they cannot engage their stay apparatus
What is the purpose of splinting the carpus in extension in horses with a dropped elbow?
To allow weight to be supported on the affected limb
what is the artery responsable for the scapulohumeral joint?
brachia artery and vein
axillary artery and vein
the cephalic vein diverges from external jugular and continues distad in the groove between (name the 2 muscles)
Brachiocephalicus
descending pectoral
The radial nerve supplies the extensor or flexor muscles of the distal shoulder?
Extensor
What happens in total loss of radial nerve and partial nerve?
proximal (totaL) nerve paralysis loss function of the extensors of the thoracic limb (anconeous + triceps muscles
distal radial paralysis (partial/less severe) ONLY extensor carpus muscles and digit are affect (dorsal surface of the hoof touch the groun, horse can’t bear weight)
which nerve is responsable for the palmar region and flexor portion of the limb?
Musculocutaneous
Median
Ulnar
The musculocutaneous nerve joins the _____ nerve proximally after supplying the coracobrachialis and biceps brachii and brachialis muscles
median nerve
The median nerve innerveates the flexor carpi radialis, humeral and radial heads of the ________
deep digital flexor
Is it common to have ulnar and median nerves affected?
No, and usually one nerve compensates the other
Ulnar nerve courses along the caudal border of _________artery before passing over the medial epicondyle of the humerus and entering the forearm
brachial artery
which muscles stabilize the shoulder (name the 4)
Supraspinatus
Infraspinatus
Subscapularis
Teres minor
does shoulder have collateral ligaments?
no, instead it has small glenohumeral ligaments
which muscle is the main stabilizer of the shoulder?
the biceps tendon it partially blocks the shoulder joint when it passes in teh intertubercular groove
What is the differential diagnosis of dropped elbow (NAME 4)
Triceps myopathy
Huemral fracture
Olevranon fracture
Radial neuropathy
What type of ulna fracture can you consider conservative tx?
NON-ARTICULAR + NON DISPLACED fractures = TYPE 5
Prolonged convalescent perod, healing is slow
What is reported in horses with type 5 fractures managed conservatively?
Functional soundness in a small number of cases
Why do horses with type 5 fractures that are managed conservatively have a prolonged convalescent period?
Due to the instability of the fracture
Why might surgical treatment be preferred despite the inherent risks?
It leads to improved patient outcomes and shorter
What is the main concern with type 5 fractures that do not violate the articular surface?
isk of degenerative articular changes
Why might synovial fluid entering the fracture line be problematic?
It disrupts healing and may lead to pseudarthrosis
What is indicated for open, articular fractures in horses?
Immediate surgical intervention
In horses with a dropped elbow, what reduces anxiety and minimizes fatigue of the contralateral limb?
Splinting the limb in extension
What is the preferred treatment for articular or displaced fractures of the olecranon in horses?
Open reduction and internal fixation (ORIF)
What principle is used in stable fixation of olecranon fractures?
A. The compression-band principle
B. The tension-band principle
C. The immobilization principle
D. The flexibility principle
B. The tension-band principle
How is tension-band fixation usually accomplished?
Using a plate applied to the caudal aspect of the olecranon
What is another method employed for tension-band fixation beside the plate?
Tension-band wire fixation
Where should screws not penetrate during the surgical approach to olecranon fractures?
A. The articular cartilage
B. The trochlear notch
C. The joint
D. The anconeal process
C. The joint, the screws at the level of trochlear notch should not penetrate joint
describe the incision and surgical acess for fracture of the ulna repair
GA - LR - the skin incision proximally in lateral direction to avoid the point of the elbow. Wounds should also be avoided when approaching the fracture.
After the skin and subcutaneous fascia have been incised, deep dissection between the ulnaris lateralis muscle and ulnar head of the deep digital flexor tendon exposes the caudal and lateral aspects of the olecranon and ulna.
Distally, the ulna is exposed for plate application by subperiosteal dissection.
Proximally, the** caudal and lateral aspects of the olecranon are closely invested in the dense fibrous connective tissue aponeuroses of the ulnar head of the deep digital flexor and flexor carpi ulnaris muscles.**
Sharp dissection of the fibrous connective tissue attachments from the olecranon is necessary for plate application. Additional dissection exposes the proximal aspect of the olecranon tuberosity for fixation of **types 1 and 3 fractures. In these cases, the insertion of the triceps** is sharply divided in the sagittal plane parallel to the longitudinal fiber bundles, and dissected abaxially at their insertion on the olecranon far enough to accommodate the width of the plate. Once exposed, the bone is inspected for hair line fractures
describe the insertion of plate in the ulna once the dissection was performed
4.5 mm LCP or DCP plate Contoured plate is applied by positioning **one screw proximal **and **another screw distal to the fracture with the fracture held in reduction.
It is important to apply the plate to the caudal border** and not to the caudolateral aspect to prevent screws from exiting through the medial aspect of the olecranon tuberosity proximally and potentially impinging on the medial epicondyle of the humerus. The** first cortex screw** is placed in the proximal fragment using the neutral drill guide. This screw is not tightened completely, and the plate is displaced distally before placing the second cortex screw in the distal fragment using the load drill guide.
Tightening of these two screws compresses the fracture and brings the plate into contact with the underlying bone. Overcompression of minimally displaced fractures with comminution at the articular surface can result in fragment displacement.
Therefore screws should be applied in the neutral position with comminuted fractures.At this point in the repair, an intraoperative LM radiograph should be obtained to assess the fixation(Figure 96-7).
The intraoperative radiograph can be used to evaluate the adequacy of reduction and screw position and as a guide for directing and gauging the approximate length of the remaining screws.If further compression is needed, an additional cortex screw on either side of the fracture can be placed in the** load configuration.**
Before tightening these additional load screws, the previously placed screw in the same fragment should be loosened slightly (see Chapter 77).
The remainder of the cortex screws are placed in the neutral position. If an LCP is used, one or two locking screws are placed on either side of the fracture with another locking screw positioned at either end of the plate. Screw placement in the proximal fragment must avoid penetration of the concave medial cortex. By aligning the drill bit parallel to a Steinman pin inserted along the medial aspect of the olecranon process in a cranial direction, the surgeon is assured that the drill hole will exit at the cranial border of the bone. Screws at the level of the trochlear notch should not penetrate the joint.Distally, screws should not engage the caudal cortex of the radius in foals.
If the fracture is transverse initial screws on each side of fracture are placed in load
oblique fracture a** lag screw** can be placed on each side or through the plate to reduce fracture
what is the prognosis for plate fixation in olecranon fractures?
conservative 33%
Surgical 72-83% (article Jimenez EVE 2023)
favorable 68-76%
Type 1 b - 81%
Type 2 - 80%
Type 4 -30%
Type 5 - 85%
What factors influence the decision between surgical and conservative treatment for olecranon fractures?
Fracture type, stability, displacement, articular involvement, triceps engagement, and patient risk factors.
What is the benefit of using a locking compression plate (LCP) in equine fracture repair (Jimenez EVE 2023)
It withstands tension stresses during healing and reduces the need for precise bicortical screw placement.
Jimenez - Rihuete EVE 2023 Why are standing surgeries preferred for some equine olecranon fractures?
They avoid the risks associated with general anesthesia, such as recovery-associated catastrophic fractures.
Jimenez - Rihuete EVE 2023 What are the risks associated with standing surgical repair?
Higher risk of infection, challenges in achieving precise screw trajectories, and potential injury to the surgical team.
Jimenez - Rihuete EVE 2023 How does the use of self-tapping screws benefit equine standing surgeries?
It reduces surgery time by eliminating the need to tap predrilled holes.
what is the particularty about the screws placement in foals vs adults in the ulna?
in foals or young horses AVOID place screws across the ulna and into the radius
adults mature placing screws across ulna into the radius can offer additional strengh
In adults in comminuted fractures a second plate laterally can be placed
What surgical technique is used to remove a comminuted anconeal process?
Flexing the leg and removing the fragment through the fracture gap
How is reduction achieved in displaced fractures?
By applying caudal and distal traction
What is used to model plate contouring once the fracture is reduced?
A soft aluminum template
How many cortices should the plate engage on either side of the fracture?
At least five
What type of plate is ideally used for fixation?
A. A narrow plate, ideally a locking compression plate (LCP)
B. A broad plate
C. A flexible plate B. A broad plate
C. A compression plate
D. A custom-made plate
A. A narrow plate, ideally a locking compression plate (LCP)
How is the first cortex screw placed in the proximal fragment?
First screw in proximal fragment with neutral guide in compression hole without penetration of medial cortex and not tightened completely, plate is pulled distally and 2nd screw is placed in distal fragment with load drill guide, both screws tightened alternately to compress fragments
What should be obtained intraoperatively to assess the fixation?
Lateromedial radiograph
What should be avoided in screw placement in the proximal fragment?
Penetration of the concave medial cortex
What type of screws may be used if an LCP is employed?
Locking screws and cortex screws
What is a critical consideration when placing screws in the distal end of the plate?
Avoiding the lateral cortex of the radius, specially if you use LHS screws so avoid it
When is engaging the caudal cortex of the radius not recommended in foals?
In foals younger than 1 year of age
What is the advised treatment if subluxation occurs post-surgery?
Osteotomy of the body of the ulna
What is a challenge in fixing types 1 and 3 fractures?
The small size of the proximal fragment
For a type 1b fracture, where is the plate contoured?
Over the proximal aspect of the apophysis
What adds strength to the fixation of type 1b fractures?
Purchase in the cranial cortex of the olecranon
What is important to avoid in type 1b fractures to prevent displacement?
Overcompressing the caudal aspect of the fracture
Which type of fracture was the most common configuration encountered in the studies?
Type 2
What percentage of type 4 fracture patients returned to full function according to the studies?
29%
What is the reported long-term outcome for horses with type 1b fractures?
81% were sound
What percentage of horses treated with LC P fixation were sound for their intended purpose?
83%
What is the ideal candidate weight for tension-band wire fixation?
200 kg or less
What type of fractures are best suited for tension-band wiring?
Simple fractures
What is the union rate for fractures managed with tension-band wiring?
82%
What is the advantage of tension-band wiring compared to plate fixation?
Less risk of screws entering the joint space
What is the recommended treatment for fractures in foals and weanlings?
At least two or three 1.2-mm diameter cerclage wires
Figure 96-5. (A) Photograph of a wound associated with a type 2 olecranon fracture. (B) Lateromedial contrast arthrogram radiographic image demonstrating articular communication with the wound.
Figure 96-6. Intraoperative image showing opening of a fracture to allow removal of the anconeal process fragment through the fracture gap. The articular cartilage of the humeral condyle is visible through the fracture gap.
Figure 96-7. Intraoperative lateromedial radiographic view documenting fracture reduction and plate application by means of a proximal and distal 4.5-mm cortex screw. Subsequently, the remaining cortex screws are placed in lag fashion through the narrow DCP into the cranial cortex of the olecranon in a type 1b fracture.
Figure 96-8. (A) Mediolateral radiographic image of a type 5 ulnar fracture with associated anconeal process fracture (arrow). (B) Postoperative mediolateral radiographic view of the fracture repair demonstrating complete removal of the anconeal process fragment (arrow), application of an 11-hole narrow 4.5-/5.0-mm LCP with cortex screws placed in load configuration on either side of the fracture to achieve axial compression, and the remaining plate holes filled with locking head screws. (C) Postoperative craniocaudal radiographic view demonstrating the placement of the two most distal screws with angulation towards the central axis to avoid penetration of the lateral cortex of the radius. Antibiotic impregnated PMMA beads were placed adjacent to the implants.
Figure 96-9. Illustration of the placement of a Steinman pin parallel to the medial aspect of the olecranon process, allowing parallel drill alignment to the pin and exit of the drill bit at the cranial border of the olecranon process.ABC
Figure 96-10. (A) Follow-up radiographic views of a mid-diaphyseal radius fracture in a foal treated with bone plates. The fracture shows progressive healing; however, there is a subluxation of the elbow joint. (B) An ulnar osteotomy was performed 10 days prior to taking this radiograph, which resulted in correction of the subluxation and restoration of the normal joint anatomy. An osteotomy gap of 10 mm developed. (C) The 6-year follow-up of the same animal included a radiographically normal configuration of the joint without osteoarthritis and a sound animal. (Courtesy G. Bodo, Budapest, Hungary.)
Figure 96-11. Postoperative mediolateral oblique radiographic view of a repaired type 1b articular ulnar fracture. Note the two long interfragmentary screws reaching to the cranial edge of the olecranon process.
Figure 96-12. (A) Preoperative mediolateral radiographic view of a type 5 ulnar fracture. (B) Postoperative mediolateral radiographic view of the fracture repaired with a single 4.5-mm cortex screw placed in lag fashion supported by two 1.25-mm cerclage wires placed through separate drill holes located proximal and distal to the fracture and tightened caudally. (C) Postoperative craniocaudal radiographic view demonstrating the figure-of-eight wire placement.
type 2 fracture
Radiograph of the right elbow after surgery, showing a complete reduction of the fracture
how do you transport an ulna fracture?
single cranial splint
extending from proximal antebrachium to distal metacarpus
applied over a relatively light bandage to minimize
the pendulum effect while protecting the skin
(Figure 7.24a).
what is wrong?
Figure 11.7 Post-operative
radiograph after fixation of a type
IV ulnar fracture. The most distal screw is too long and has bent
as a result of contact with the cranial cortex of the radius: the
screw could not be tightened because the thread hole was
damaged. The second screw is also too long and has contacted
the subchondral bone so that the screw has bent and its head
has not engaged the plate.
what is wrong?
Figure 14.2 Partial implant failure. Lateromedial radiograph
two weeks after fixation of a type IV ulnar fracture. Screw
bending (closed arrows) and loosening (open arrow) suggest
instability.
Figure 26.2 Comminuted and widely displaced fracture of the
olecranon tuberosity sustained by a broodmare in recovery from
general anaesthesia for dystocia.
Figure 26.3 Apophyseal fractures. (a) Salter–Harris type I avulsion with proximal and cranial displacement of the apophysis in a foal.
Figure 26.3proximal and cranial displacement of the apophysis in a foal.
Figure 26.10 Radiographic development of the ulnar apophysis in the first 18 months of life.
Lateral recumbency in horse to be submitted to surgery of ulna
Figure 26.13 Surgical approach to the left ulna demonstrated on a cadaver limb. (a) Palpation of the groove between the muscles of
ulnaris lateralis (lateral) and ulnar head of the deep digital flexor (medial) on the caudal antebrachium distal to the olecranon. (b) A
linear incision over the groove, extending from the level of the distal ulnar diaphysis proximally before curving laterally over the
olecranon tuberosity and terminating at the caudal insertion of triceps brachii. (c) Division of the thick antebrachial fascia revealing
the fascial plane between ulnaris lateralis and the ulnar head of the deep digital flexor. (d) Ulnaris lateralis and the ulnar head of the
deep digital flexor are separated by blunt (digital) dissection to expose the caudal surface at the ulna. Self-retaining
retractors are
inserted between the two muscles proximally and distally. The thin muscle overlying the caudal distal diaphysis of the ulna is the
ulnar origin of the radial head of the deep digital flexor.
type 1a olecranon fracture (through apophysis)
type 1b ( articular) olecranon fracture (starts through apophysis and break into joint)
type 1b (non articular) olecranon fracture (starts through apophysis and break into metaphysics to joint)
Type 2, simple fracture through the body of the olecranon with articular involvement;
Type 3, simple fracture through the body of the olecranon without articular involvement;
Type 2, simple fracture through the body of the olecranon with articular involvement;
Type 3, simple fracture through the body of the olecranon without articular involvement;
Type 4, multifragment fracture of the olecranon with or without articular involvement;
Type 5, distal oblique ulnar fracture with marginal articular involvement.
First aid for radial fracture:
Immediate immobilization with Robert Jones bandage and splint under sedaton
Figure 96-14. An appropriate external coaptation of a radius fracture in an adult horse before surgical repair. Note the contact between the lateral splint and the brachium and shoulder when the limb is positioned directly beneath the body (A). A caudal splint extending from the ground to the olecranon process is also present (B). The splints are affixed with fiberglass casting tape.
Figure 96-15. Craniocaudal (A) and lateromedial (B) radiographic views of a nondisplaced fracture of the radius in an adult horse secondary to a kick injury.
VetBooks
Figure 96-16. (A) Caudomedial–craniolateral oblique radiographic view demonstrating presence of the medially located wound (vertical arrow) and the vaguely evident fracture line (double arrow). (B) Craniocaudal radiographic view of the same bone 7 days later revealed a more evident fracture. (C) Caudomedial–
craniolateral oblique radiographic image taken at presentation to the hospital 1 day after the image shown in Figure 96-16, B had been taken. The fracture is complete, comminuted, displaced, and open.
Figure 96-17. Craniocaudal radiographic view of a comminuted radial fracture in an adult horse before internal fixation (A) and after application of a 4.5-mm DCS plate applied to the lateral cortex and a 4.5-/5.0-mm LCP applied to the cranial cortex (B). The plates span the length of the radius (not visible on the radiographs). A lateral radiographic view (C) demonstrates the importance of distal placement of the implants because of the configuration of the fracture and short distal fracture segment.
Figure 96-18. Craniocaudal radiographic view of a radial fracture in an adult horse before internal fixation (A), and after application of a 4.5-mm DCS plate applied to the cranial cortex and a broad 4.5-mm DCP applied to the lateral cortex. Note the lateral plate was rotated into a craniolateral position (B). A lateral radiographic view (C) demonstrates the cranial and proximal placement of the DCS because of the more cranial location of the fracture fragment.
Figure 96-19. Craniocaudal radiographic view of a proximal metaphyseal radial fracture in a foal before internal fixation (A), and after application of a 4.5-mm DCP to the cranial cortex and a 4.5-mm narrow DCP applied to the lateral cortex distally and spiraled cranially at its proximal aspect (B).
Figure 96-20. (A) Craniocaudal and lateromedial radiographic views of a middiaphyseal radius fracture in a 2-week-old foal supported by a caudal PVC-pipe splint upon presentation at the clinic. (B) Craniocaudal and lateromedial postoperative radiographic views of the radius following application of a 15-hole reinforced 3.5-mm LCP to the cranial aspect of the bone.
Figure 96-21. Craniocaudal radiographic view of a Salter-Harris type II fracture of the proximal radius prior to repair (A), and after the application of a narrow 4.5-mm DCP to the lateral aspect of the proximal radius, and a narrow 4.5-/5.0-mm LCP applied to the ulna (B). Lateral radiographic view (C) demonstrates screws transfixing the ulna to the radius. AIPMMA beads are present adjacent to the implants.
Figure 96-23. Craniocaudal radiographic view of a foal with a Salter-Harris type I fracture of the distal radius before (A) and after repair with a transphyseal bridge using screws and wires (B). Note the separate center of ossification (the lateral styloid process), which represents morphologically the distal end of the ulna and fuses with the distal radial epiphysis in the first year of life. This separate center should not be confused with a fracture line.
Figure 96-22. Lateromedial radiographic view of Salter-Harris type II fracture of the proximal radius accompanied by an ulnar fracture with cranial displacement of the distal fragment, resulting in temporary radial nerve paresis.
Figure 96-24. Craniocaudal radiographic view of a radial fracture in an adult horse following internal fixation with a dynamic condylar screw plate and broad DCP (A) and 25 days later, following cyclic fatigue and implant failure secondary to development of support limb laminitis (B).
Figure 96-25. Craniocaudal radiographic view of a radial fracture in an adult horse following internal fixation with a cranially applied 4.5-mm DCS plate and laterally applied broad DCP (A), and 5 months later, following cyclic fatigue and implant failure secondary to implant infection and delayed union resulting in humane euthanasia (B).
diagnosis
Figure 96-26. Lateromedial radiographic view demonstrating a solitary osteochondroma of the caudal aspect of the radius proximal to the distal physeal scar.
Figure 96-27. Endoscopic view of a caudal radial osteochondroma before its removal. Note the injury to the deep digital flexor tendon on the right side of the photograph caused by the osteochondroma.
Figure 96-29. Craniocaudal radiographic view of the proximal medial radial subchondral cystic lesion seen in Figure 96-28 following débridement and transcystic position 4.5-mm cortex screw placement. The drill tract placed to facilitate transosseous débridement of the cyst prior to screw placement can be seen extending distomedially from the lesion
Figure 96-30. Craniolateral approach to the elbow joint (A). Illustration of the accessible regions (highlighted in white) of the elbow joint using this approach (B). CDE, Common digital extensor muscle; ECR, extensor carpi radialis muscle; LCH, lateral condyle of the humerus; MCH, medial condyle of the humerus; SF, synovial fossa of the humerus.
Figure 96-32. Caudoproximal approach to the elbow joint (A). Illustration of the accessible regions (highlighted in white) of the elbow joint using this approach (B). AP, Anconeal process of the ulna; LCH, lateral condyle of the humerus; LEH, lateral epicondyle of the humerus; MCH, medial condyle of the humerus.
