Fractures and Growth Deformities of the Radius and Ulna, Luxation of the Elbow

Chapter 105 Fractures and Growth Deformities of the Radius and Ulna, Luxation of the Elbow



James Tomlinson



FRACTURES OF THE RADIUS AND ULNA


Fractures of the radius and ulna are commonly seen in small animal practice. Although most of these fractures occur as a result of automobile accidents, they also result from falling or jumping. Fractures of one or both bones and a wide variety of fracture types are seen. Open fractures of the distal one-half of the radius and ulna are common, owing to minimal soft tissue coverage. Complications include delayed union, nonunion, joint stiffness, and arthritis.



Anatomy



Radius



• The radius and ulna make up the antebrachium.

• The radius is the main weight-bearing bone of the antebrachium and is shorter than the ulna. The radius is composed of the head, neck, body, and distal extremity. The medullary canal is elliptical in shape owing to flattening of the radius.

• The radius is attached to the ulna by an interosseous ligament that helps to maintain their spatial relationship following fracture. The short radial collateral ligament runs from the styloid process of the radius to the radial carpal bone and provides medial support to the antebrachiocarpal joint.

• The cranial surface of the distal radius contains three grooves that contain (from medial to lateral) the tendons of abductor pollicis longus, extensor carpi radialis, and common digital extensor muscles.


Ulna



• The ulna is the longest bone in the body and is composed of the olecranon, trochlear notch, anconeus, body, and the distal extremity called the styloid process.

• The olecranon has a strong muscular attachment, the triceps muscle.

• The ulnar body tapers as it crosses caudal to the radius to articulate with the palmarolateral aspect of the carpus. The medullary canal of the ulna functionally ends about one-third from the distal end.

• The strong, short ulnar collateral ligament runs from the tip of the styloid process of the ulna to the ulnar carpal bone, giving lateral support to the antebrachiocarpal joint.


Vascular Supply



• The radial and interosseous arteries provide the main arterial supply to the antebrachium and are subject to injury from trauma or surgery.

• The radial artery travels along the palmaromedial aspect of the radius just under the flexor carpi radialis muscle.

• The interosseous artery branches into other interosseous arteries that run in the space between the radius and ulna.


Nerve Supply



• The radial, median, and ulnar nerves supply the antebrachium and manus.


General Preoperative Considerations



• Evaluate the thorax for pulmonary contusions, pneumothorax, and diaphragmatic hernia with thoracic radiography. Evaluate for traumatic myocarditis with electrocardiography.

• Examine the animal for concurrent injuries; inspect other limbs for fractures or other significant injury.

• Inspect the antebrachium for evidence of wounds indicating an open fracture.

• Evaluate nerve function of the affected limb by testing reaction to a painful stimulus to the skin of the various dermatomes and by withdrawal of the limb.

• Initially place the limb in a Robert Jones bandage or splint to prevent further soft tissue damage and to prevent the fracture from becoming an open fracture.

• Obtain two radiographic views of the fractured limb to include the elbow and carpus.


General Objectives of Surgical Procedures



• Align and stabilize the fracture(s) to permit uncomplicated healing with normal joint and limb function.



Key Point


Exact anatomic alignment and rigid fixation (compression) of articular fractures is imperative.



• Allow early return to weight bearing.

• Preserve neurovascular structures during repair.


General Postoperative Care and Complications for Radial and Ulnar Fractures



• Place the limb in a soft padded bandage for 3 to 10 days to reduce postoperative swelling. Provide more rigid external support if needed.

• Reevaluate the fracture radiographically every 3 to 4 weeks until the fracture has healed.

• Restrict activity until the fracture has healed.


Complications



• Delayed and nonunion healing (see Chapter 122), osteomyelitis (see Chapter 121), and implant failure may occur.

• Joint fractures are prone to subsequent degenerative joint disease and callus that interferes with joint mobility if anatomic alignment and rigid stability have not been achieved.

• Joint stiffness can develop with articular fractures. Rigid stability of the fracture allows early, controlled use of the joint.



Key Point


Radius and ulna fractures in immature animals may cause premature closure of the growth plates and synostosis of the radius and ulna. Both conditions cause growth deformities of the limb. Early recognition and intervention is necessary to minimize growth deformities.



Olecranon Fractures



Objective



• Counteract the distractive force of the triceps and convert it into a compressive force using the tension band principle.


Equipment



• General surgery pack and standard suture material

• Monofilament stainless steel surgical wire (20 and 18 gauge)

• Intramedullary pins and Kirschner wires (K-wires)

• Jacobs chuck or power drill

• Wire-tightening device (vise grips or wire twister)

• Pin and wire cutter

• Bone reduction forceps


Technique



1. Place the patient in lateral recumbency, with the affected leg up, and prepare the limb for aseptic surgery.

2. Make a caudolateral skin incision centered over the olecranon.

3. Reflect the skin and subcutaneous tissue to expose the olecranon and proximal shaft of the ulna. Subperiosteally elevate the extensor and flexor carpi ulnaris muscles from the proximal shaft of the ulna.

4. Reduce the fracture and hold it in reduction with bone reduction forceps.

5. Drive two K-wires or small intramedullary pins parallel from the tip of the olecranon across the fracture line and into the distal segment of the ulna (in very small animals, drive only one K-wire).

6. Drill a hole (perpendicular to the ulnar long axis) in the distal ulnar segment 1.5 to 2 times the distance from the olecranon to the fracture line.

7. Insert surgical wire in the hole and place the wire around the pins in a figure-eight fashion.

8. Twist the wire to achieve equal tension on the wire.

9. Bend the pins over and cut them off short. Cut the wires leaving two to four twists and bend the wire tips over (Fig. 105-1).

10. Close the subcutaneous tissue and skin routinely.

image

Figure 105-1 Pin and wire placement for olecranon fracture repair.



Trochlear Notch Fractures



Objectives



• Maintain precise anatomic alignment of the fracture (because it is an articular fracture).

• Perform rigid fixation of the fracture to minimize periosteal callus.

• Counteract the distractive forces of the triceps muscle using the tension band principle.


Equipment



• Same as for olecranon fractures with the addition of bone plating equipment.


Technique



Small and Medium-Sized Dogs; Cats; No Fracture Comminution Present



1. Repair the fracture with a tension band wiring technique, as described previously under Olecranon Fractures.

2. Maintain anatomic alignment of the fracture while driving the pins and tightening the wire in a figure-eight configuration.


Large Dogs; Fractures with Comminution



1. Expose the trochlear notch, as described for olecranon fractures.

2. Reattach butterfly segments of bone with lag screws and Kirschner wires.

3. Contour a bone plate to the caudal or caudolateral side of the ulna and secure it to the ulna with bone screws (Fig. 105-2).

4. If comminution is not present, apply the plate with a compression technique. If comminution is present, apply the plate in a neutralization manner (e.g., no compression).

image

Figure 105-2 Bone plate and screw replacement for trochlear notch fracture repair.



Radial Head Fractures



Objective



• Perform precise anatomic reduction of the fracture with rigid fixation of the fragments.


Equipment



• General surgery pack and standard suture material

• Hohmann retractor

• Bone screws and bone screw insertion equipment

• Power drill and Jacobs pin chuck

• K-wires


Technique



1. Place the patient in lateral recumbency, with the affected limb up, and prepare the limb for aseptic surgery.

2. Incise the skin, beginning at the proximal end of the lateral epicondyle of the humerus and continuing distally over the radial head to the proximal one-fourth of the radius.

3. Incise the subcutaneous tissue and the antebrachial fascia along the same line to expose the extensor muscles of the antebrachium.

4. Dissect between the ulnaris lateralis muscle and the lateral digital extensor. Cut the ulnaris lateralis tendon, leaving sufficient tendon for suturing. If necessary, incise the anconeus muscle from the lateral epicondyle of the humerus.

5. Reflect the lateral digital extensor muscle cranially with a Hohmann retractor to expose the fracture.

6. Drive a K-wire across the fracture line to hold the fracture in reduction.

7. Insert a screw in “lag screw” fashion to compress the fracture line.

8. For small fragments, place two or three K-wires in a divergent pattern.

9. Reattach the ulnaris lateralis tendon with non-absorbable monofilament suture material in a horizontal mattress pattern. Suture the muscle fascia and subcutaneous tissue in a simple continuous pattern, using absorbable suture material. Close the skin routinely.


Radial Neck and Proximal Physeal Fractures



Objectives



• Stabilize the fracture in immature animals without fracture compression to help prevent premature closure of the growth plate.

• Stabilize and align the radial head so that it articulates properly with the humeral condyle.


Equipment



• General surgery pack and standard suture material

• Jacobs pin chuck

• K-wires


Technique



1. Approach the fracture as described for radial head fractures, and reduce the fracture.

2. Stabilize the fracture with two K-wires placed in cross-pin fashion from the lateral side. Start one pin just below the articular surface of the radius and drive it distomedially. Start the second pin distal to the fracture and drive it proximomedially.

3. Bend the pins over and cut them off short.

4. Take care not to penetrate the articular surface of the radius.

5. Close the incision as described under Radial Head Fractures.


Postoperative Care



• Remove the K-wires in 3 to 4 weeks and monitor for premature closure of the growth plate.


Monteggia Fractures


This is a fracture of the ulna that can occur at various levels, combined with a radial head luxation.



Objectives



• Reduce and stabilize the radial head luxation.

• Align and stabilize the ulnar fracture.


Equipment



• General surgery pack and standard suture material

• Bone plating equipment

• Power drill

• Bone reduction forceps


Technique



1. Expose the ulnar fracture, as described under Olecranon Fractures and Trochlear Notch Fractures. Expose the ulna as far distally as needed.

2. Expose the radial head, as described under Radial Head Fractures, if the luxation cannot be reduced closed.

3. Reduce the ulnar fracture and hold it in reduction with bone reduction forceps.

4. If the annular ligament is ruptured, contour and apply a bone plate to the caudal aspect of the ulna. Insert a screw in “lag screw” fashion into the radius from the ulna through the plate to secure the radial head in position (Fig. 105-3).

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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Fractures and Growth Deformities of the Radius and Ulna, Luxation of the Elbow

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