Chapter 14

Open Reduction and Internal Fixation of Capitellum and Capitellar-Trochlear Shear Fractures

 

Asif M. Ilyas Michael Rivlin Jesse B. Jupiter

 

 

DEFINITION

Capitellar fractures are uncommon, accounting for less than 1% of all elbow fractures and 6% of all distal humerus fractures.4

They often are associated with radial head fractures and posterior elbow dislocations.

A classification system for capitellar fractures has been proposed by Bryan and Morrey4 and modified by McKee:

Type 1: complete fractures of the capitellum14

Type 2: superficial subchondral fractures of the capitellar articular surface29 Type 3: comminuted fractures2

Type 4: coronal shear fractures that include a portion of the trochlea as well as the capitellum as one

piece21 ( FIG 1)

Ring et al25 have proposed a new classification, expanding on the growing understanding that isolated capitellum fractures are rare and often are involved as part of articular shear fractures of the distal humerus. The classification includes five anatomic components, with type 1 articular injuries encompassing the capitellum and capitellar-trochlear shear patterns ( FIG 2):

Type 1: capitellum and lateral aspect of the trochlea Type 2: lateral epicondyle

 

 

 

FIG 1 • Type 4 coronal shear fractures of the distal humerus. (Adapted from McKee MD, Jupiter JB, Bamberger HB, et al. Coronal shear fractures of the distal end of the humerus. J Bone Joint Surg Am 1996;78[1]:49-54.)

 

 

 

Type 3: posterior aspect of the lateral column Type 4: posterior aspect of the trochlea

 

Type 5: medial epicondyle

 

More recently, Dubberley and colleagues8 introduced a classification system based on radiographic pattern of injury taking posterior comminution into account.

 

 

Type 1: fracture of the capitellum (with or without trochlear ridge involvement) Type 2: capitellum and trochlea fracture that remain as one fragment

 

 

Type 3: capitellum and trochlea as separate fragments Type A: no posterior condyle comminution

 

Type B: posterior condyle comminution present

 

ANATOMY

 

The two condyles of the distal humerus diverge from the humeral shaft to form the lateral and medial columns, which support the trochlea between them. The anterior aspect of the lateral column is covered with articular cartilage, forming the capitellum. Distally, these two condyles can be visualized as forming a triangle at the end of the humerus.

 

The capitellum is the first epiphyseal center of the elbow to ossify.

 

 

 

FIG 2 • Articular fractures of the distal part of the humerus, including type 1 fractures that encompass capitellum and capitellar-trochlear shear fractures. (Adapted from Ring D, Jupiter JB, Gulotta L. Articular fractures of the distal part of the humerus. J Bone Joint Surg Am 2003;85-A[2]:232-238.)

 

 

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It is covered by articular surface anteriorly but devoid of it posteriorly.

 

The capitellum is directed distally and anteriorly at an angle of 30 degrees to the long axis of the humerus.

 

 

The radial head rotates on the anterior surface of the capitellum in elbow flexion and articulates with its inferior surface in elbow extension.

 

The lateral collateral ligament inserts next to the lateral margin of the capitellum.

 

The blood supply of the capitellum is derived posteriorly. It arises from the lateral arcade, which is the anastomosis of the radial collateral arteries of the profunda brachii and the radial recurrent artery.30

PATHOGENESIS

 

Capitellum and capitellar-trochlear shear fractures involve impaction of the radial head against the lateral column of the distal humerus in a partially extended position, resulting in shearing of the articular cartilage of the distal humerus.

 

Fracture fragments vary in size and displace superiorly and anteriorly into the radial fossa, resulting in impingement with elbow flexion.

 

Associated injuries include proximal and distal radial as well as carpal fractures; ligamentous injuries include collateral ligament (lateral more common than medial) and triceps ruptures.8

NATURAL HISTORY

 

Capitellar fractures occur almost exclusively in adults. These fractures do not occur in children because in that age group, the capitellum is largely cartilaginous, and a similar mechanism of injury would instead cause a supracondylar or lateral condyle fracture.

 

Capitellar fractures are more common in females, a finding that can be attributed to the increased carrying angle of the female elbow.

 

Displaced fractures that go untreated can be expected to have a poor outcome owing to the progressive loss of motion from the mechanical block to flexion, potential longitudinal instability of the forearm, and the likely development of subsequent posttraumatic arthrosis from the residual articular incongruity.

 

 

 

FIG 3 • A. Characteristic double arc sign on lateral radiographs of coronal shear fractures. B,C. 3-D CT reconstructions of a coronal shear fracture of the distal humerus.

 

 

Capitellar and trochlear fractures are prone to nonunion if multiple articular fragments are present or the posterior column is involved.3

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Symptoms of capitellar fractures are similar to those of radial head fractures, including pain and swelling along the lateral elbow and pain with elbow motion.

 

Although there may be variable loss of forearm rotation, loss of flexion and extension is most common, often accompanied by crepitus and pain.

 

 

The association of concomitant radial head fractures and ligamentous injuries with capitellar fractures is high.22 The shoulder and wrist should also be examined for concomitant injury.

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

 

Standard radiographs are often inadequate for accurate assessment of capitellar fractures. Lateral radiographs are best for obtaining an initial evaluation of capitellar fractures.

 

Anteroposterior views do not reliably show the fracture because the outline of the distal humerus is not consistently affected.

 

The radial head-capitellum view can help identify fractures of the capitellum. This view is a lateral oblique projection taken with the x-ray beam pointing 45 degrees dorsoventrally, thereby eliminating the ulno- and radiohumeral articulation shadows.13

 

A type 1 fracture appears as a semilunar fragment sitting superiorly with its articular surface pointing up and

away from the radial head in most cases.

 

Type 2 fractures are more difficult to diagnose, depending on the amount of subchondral bone accompanying the articular fragment. They may appear as a loose body lying in the superior part of the joint.

 

Type 3 fractures display variable amounts of comminution.

 

Coronal shear fractures show a characteristic “double arc” sign on lateral radiographic views (FIG 3A).

 

Computed tomography (CT) scans can provide excellent characterization of the fracture, and we subsequently recommend routine use of it for preoperative planning.

 

 

CT scanning of the elbow should be done at 1- to 2-mm intervals using axial or transverse cuts.

 

 

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Three-dimensional (3-D) CT reconstructions provide the best detail and ability to appreciate the anatomic orientation of the fracture patterns and should be considered if 3-D imaging is available (FIG 3B,C).

 

DIFFERENTIAL DIAGNOSIS

Radial head fracture

Distal humeral lateral condyle fracture Elbow dislocation

 

 

NONOPERATIVE MANAGEMENT

 

We recommend operative management for capitellum and capitellar-trochlear shear fractures.

 

Truly nondisplaced and isolated capitellum fractures can be splinted for 3 weeks, followed by protected motion. However, close supervision is required, as this fracture is inherently unstable and prone to displacement.

 

Closed reduction techniques, which have been described in the literature, should be performed with caution, and only complete anatomic reduction should be accepted for nonoperative management.5, 23

 

Capitellar-trochlear shear fractures should not be treated nonoperatively because of their inherent instability and the expectant loss of motion and posttraumatic arthrosis from residual articular incongruity.

 

SURGICAL MANAGEMENT

 

The short-term goal of surgery is anatomic reduction and stable fixation of the fracture to allow for early motion without mechanical block.

 

The long-term goals of surgery are a pain-free elbow with maximal motion, minimal stiffness, and avoidance of posttraumatic arthrosis.

 

Capitellar fractures are uncommon, and the wide array of treatment options presented in the literature is based on relatively small series.

 

Treatment options include closed reduction,5, 23 open excision,1, 10, 20 open reduction and internal fixation (ORIF), and arthroplasty.6, 11

 

With the improvement in techniques for fixation of small fragments and management of articular surfaces, ORIF has become the mainstay of treatment.

 

 

Advantages of ORIF include restoration of the native anatomy and function.

 

Disadvantages include stiffness and possible failure of fixation.

 

 

In elderly patients, we do consider total elbow arthroplasty for complex intra-articular distal humerus fractures.15,

17

 

 

 

Advantages include early return to function and motion. Disadvantages include functional limitations.

Preoperative Planning

 

Before proceeding with surgery, a thorough understanding of the fracture and its orientation should be obtained with the help of a CT scan, and if possible, 3-D reconstructions.

 

The timing of surgery is important. Fractures preferably should be approached within 2 weeks, before osseous healing sets in, but after swelling has diminished.

 

Ensure that the necessary implants and hardware are available.

 

Reduction and fixation of the fracture will require minimum K-wires, articular or headless screws, and small fragment AO screws.

 

Additional implants to consider include lateral column periarticular locking plates.

 

An image intensifier should be used during surgery to confirm reduction of the fracture and proper positioning of implanted hardware.

 

Positioning

 

General anesthesia is recommended for maximum soft tissue relaxation.

 

The patient usually is positioned supine on the operating table, with the arm extended onto a radiolucent hand table, facilitating the lateral approach.

 

Alternatively, a lateral or prone position can be considered, with the anterior surface of the elbow supported by a padded bolster if a posterior approach is planned.

 

Approach

 

Either a lateral or posterior midline incision should be used.

 

A lateral incision allows for direct visualization to a lateral approach to the elbow.

 

A posterior incision also allows for access to the lateral approach to the elbow but also facilitates access to the posterior and medial approaches to the elbow, if necessary.

 

Multiple intervals can be used in the lateral approach to the elbow, including the Kocher, Hotchkiss, and Wagner approaches.

 

 

We advocate the Wagner approach, which uses the interval between the extensor carpi radialis longus (ECRL) and the extensor digitorum communis (EDC), as it provides ready access to the anterolateral aspect of the radiocapitellar joint while protecting the insertion of the lateral collateral ligament complex.

 

To increase exposure, the lateral collateral ligament complex can be raised posteriorly sharply with a scalpel or osteotomized with a wedge of lateral epicondyle for subsequent suture anchor repair or internal fixation, respectively.

 

Alternatively, the Kocher approach, which uses the interval between the extensor carpi ulnaris (ECU) and the anconeus can provide access to the capitellum while affording greater protection of the posterior interosseous

nerve.

 

In many cases, a capsular violation has occurred. This can be exploited and used as the interval to expose the fracture, thereby avoiding the need to cause an additional soft tissue defect.

 

 

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TECHNIQUES

• Capitellar Fractures

  Exposure

  The incision should begin 2 cm proximal to the lateral epicondyle and extend 3 to 4 cm distally toward the radial neck.

  If no large soft tissue or capsular defect is present, a direct lateral Wagner approach between the ECRL and EDC interval is recommended.

  The remaining common extensor origin is sharply raised off the lateral epicondyle and reflected anteriorly to expose the anterolateral elbow joint.

  The capitellar fracture will most likely be found displaced anteriorly and proximally.

  Care must be taken to avoid excessive proximal dissection and injury to the radial nerve traveling between the brachialis and brachioradialis.

  Care must also be taken to avoid excessive distal dissection and injury to the posterior interosseous nerve by limiting dissection to only the radial neck. In addition, the forearm should be kept pronated, and no retractors should be placed anteriorly around the radial neck.

  Often, the lateral ligamentous complex will be avulsed from the distal aspect of the humerus, with or without some aspect of the lateral epicondyle.

  This ligamentous violation can be exploited to improve exposure by hinging open the joint on the medial collateral ligament with a varus stress.

  The capitellar fracture fragment will typically be displaced anteriorly and proximally (TECH FIG 1).

   

  TECH FIG 1 • A,B. The displaced capitellar fracture fragment will typically be displaced anteriorly and proximally and will be devoid of any soft tissue attachments.

   

  The fracture fragment will also typically be devoid of any soft tissue attachments and therefore prone to displacing out of the joint with excessive manipulation. Hence, care must be taken to avoid losing the fragment off the surgical field.

  Reduction and Fixation

   

  The fragment is reduced under direct visualization, held with reduction tenaculums, and provisionally fixed with 0.045-inch K-wires. Alternatively, the guidewires that will be used for cannulated screw fixation can be used for provisional fixation as well.

   

  Internal fixation options include fixation with (1) headless compression screws from either an anterior or posterior direction, (2) cancellous screws from a posterior direction, (3) posterolateral column locking plate fixation, or (4) a hybrid construct using any or all of these techniques.

   

  Headless compression screws allow for guidewire-directed placement, direct fracture reduction, and maximal compression of the fracture fragment. Similarly, headless compression screws may be particularly useful in cases with fragments with less subchondral bone, such as type 2 and small type 1 fracture fragments (TECH FIG 2A). However, anterior screw placement can be challenging due to the thick anterior soft tissue envelope that will be present with an intact lateral collateral ligament complex. Alternatively, headless compression screws can be placed retrograde from a posterior direction to ease hardware placement (TECH FIG 2B). However, this direction does not achieve maximum fracture compression and can risk fracture distraction.

   

  Cancellous screws are best for fracture fragments with a large subchondral component as with type 1 fracture fragments. However, extending the dissection posteriorly around the lateral column

   

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  theoretically increases the risk of osteonecrosis (TECH FIG 2C). We recommend using partially threaded cannulated screw to optimize fracture reduction, screw placement, and fracture compression.

   

   

   

  TECH FIG 2 • Fixation of capitellar fractures with (A) anteriorly placed headless compression screws, (B) posteriorly placed headless compression screws, (C) combination of a headless screw anteriorly and cancellous screws posteriorly, and (D) hybrid fixation using anteriorly placed headless compression screws followed by neutralization of the fracture with a locked periarticular plate applied posteriorly.

   

  Use of a periarticular locking plate alone or in a hybrid construct with headless compression screws can be of value to improve the stability of the construct (TECH FIG 2D). This technique will require greater posterior dissection, therefore increasing the theoretical risk of osteonecrosis. However, application of a posterolateral plate can provide posterior stability in cases with posterior cortical extension or comminution.

   

  Excision of fracture fragments can be considered in type 2 fractures with small, thin articular pieces and type 3 comminuted fractures where the fragments are not amenable to internal fixation.

   

  Fragment reduction and hardware position should be confirmed by image intensifier.

   

  Unrestricted forearm rotation and elbow flexion-extension without mechanical block or catching should be confirmed intraoperatively.

   

  If the lateral collateral ligament complex is found to be avulsed, it should be repaired back to the lateral epicondyle with drill holes and heavy nonabsorbable sutures or suture anchors.

   

  The capsule should be closed.

   

  The retracted extensor origin should be relaxed and closed to the surrounding soft tissue.

• Capitellar-Trochlear Shear Fractures

Exposure

 

A posterior midline incision should be used, but initially, a lateral approach to the joint will be performed.

 

A posterior incision provides extensile exposure, access to both sides of the elbow, and ease of osteotomy, if necessary (TECH FIG 3A).

 

A direct lateral Wagner approach between the ECRL and EDC interval is recommended.

 

The remaining common extensor origin is sharply raised off the lateral epicondyle and reflected anteriorly to expose the anterolateral elbow joint. Alternatively, a capsular violation may be present that can be exploited (TECH FIG 3B).

 

The capitellar-trochlear shear fracture will most likely be found displaced anteriorly and proximally.

 

Care must be taken to avoid excessive proximal dissection and injury to the radial nerve traveling between the brachialis and brachioradialis.

 

Care must also be taken to avoid excessive distal dissection and injury to the posterior interosseous nerve by limiting dissection to only the radial neck. In addition, the forearm should be kept pronated, and no retractors should be placed anteriorly around the radial neck.

 

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TECH FIG 3 • A. Posterior midline incision used for capitellar-trochlear shear fractures. B. Deep lateral approach to the elbow using the capsular violation to enter the radiocapitellar joint. C. The fracture fragments tend to displace proximally and internally rotate. Note, avulsion of the lateral epicondyle with subsequent retraction allowing for excellent visualization. D. The fracture is reduced and provisionally pinned with 0.045-inch K-wires.

 

 

Often, the lateral ligamentous complex will be avulsed from the distal aspect of the humerus, with or without some aspect of the lateral epicondyle.

 

This ligamentous violation can be exploited to improve exposure by hinging open the joint on the medial collateral ligament with a varus stress.

 

Alternatively, a formal lateral epicondyle osteotomy can be performed to enhance visualization while maintaining the integrity of the lateral ligamentous complex.

 

Additionally, a formal olecranon osteotomy may be performed to improve visualization and fixation of fractures extending medially and posteriorly.

 

The fracture fragments should now be visualized and accounted for. They are most commonly displaced proximally and internally rotated (TECH FIG 3C).

 

 

 

TECH FIG 4 • Postoperative radiographs illustrating (A) repair of the lateral epicondyle and anterior fixation of a capitellar-trochlear shear fracture with multiple headless compression screws. Alternatively, (B) note repair of a different capitellar-trochlear shear fracture using a periarticular locking plate applied to the posterolateral aspect of the distal humerus, facilitated with an olecranon osteotomy.

Reduction and Fixation

 

The fragment is reduced under direct visualization, held with reduction tenaculums, and provisionally fixed with 0.045-inch K-wires (TECH FIG 3D).

 

Inability to reduce the fracture anatomically may represent fracture impaction, requiring either disimpaction or bone grafting, or both.

 

Internal fixation options include fixation with (1) headless compression screws from either an anterior or posterior direction, (2) cancellous screws from a posterior direction, (3) posterolateral column locking plate fixation, or (4) a hybrid construct using any or all of these techniques.

 

Headless compression screws allow for guidewire-directed placement, direct fracture reduction, and maximal compression of the fracture fragment (TECH FIG 4A). Similarly, headless

 

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compression screws may be particularly useful in cases with fragments with less subchondral bone, such as type 2 and small type 1 fracture fragments.

 

Cancellous screws are best for fracture fragments with a large subchondral component as with type 1 fracture fragments. However, extending the dissection posteriorly around the lateral column theoretically increases the risk of osteonecrosis. We recommend using partially threaded cannulated screw to optimize fracture reduction, screw placement, and fracture compression.

 

Use of a periarticular locking plate alone or in a hybrid construct with headless compression screws can be of value to improve the stability of the construct (TECH FIG 4B). This technique will require greater posterior dissection, therefore increasing the theoretical risk of osteonecrosis. However, application of a posterolateral plate can provide posterior stability in cases with posterior cortical extension or comminution.

 

Fragment reduction and hardware position should be confirmed by image intensifier.

 

Unrestricted forearm rotation and elbow flexion-extension without mechanical block or catching should be confirmed intraoperatively.

 

The lateral epicondyle, if avulsed or osteotomized, should be repaired with a tension band technique or plate and screws.

 

The capsule should be closed.

The interval and released extensor origin should be relaxed and closed to the surrounding soft tissue.

 

 

PEARLS AND PITFALLS

Diagnosis

• Diligence should be paid to identifying concomitant injuries such as elbow

dislocations, radial head fractures, and ligamentous instability.

Imaging

• Plain radiographs are insufficient, and a CT scan should be considered routinely.

• Order 3-D reconstructions if possible.

Nonoperative

management

• Nonoperative management should be chosen cautiously. Anatomic and stable

  reduction of the fracture is necessary. Otherwise, a painful elbow with restricted motion may result.

• We do not recommend nonoperative management of any capitellar-trochlear shear fractures.

Surgical

management

• Lateral epicondyle osteotomy can enhance exposure.

• A posterior skin incision will afford access to both sides of the joint and an olecranon osteotomy, if necessary.

• Inability to reduce the fracture anatomically may represent impaction of the lateral column and require disimpaction or bone grafting.

• Excision of small comminuted fragments that cannot be fixed internally is preferred over nonanatomic reduction and malunion.

• Concomitant fractures and ligamentous injuries should be treated simultaneously to optimize outcomes.

Postoperative ▪ Stable fixation should be sought to facilitate early motion.

management ▪ Heterotopic ossification is common after elbow fractures, and prophylaxis with nonsteroidal anti-inflammatory drugs should be considered.

 

 

POSTOPERATIVE CARE

 

If secure fixation has been obtained, immediate mobilization can be initiated postoperatively.

 

If fixation is tenuous, splint or cast the elbow for 3 to 4 weeks, followed by active and assisted range-of-motion exercises. Some advocate the use of hinged external fixator for complex articular fractures or with severe ligamentous injuries.12

 

OUTCOMES

Focusing initially on outcomes after ORIF of types 1 and 2 capitellar fractures, multiple small series have shown good results using Herbert screws in an anterior to posterior direction.7, 16, 18, 24

More recently, Mahirogullari et al19 reported on 11 cases of type 1 capitellum fractures treated with Herbert screws, which yielded 8 excellent and 3 good results. They recommended fixation in a posterior to anterior

 

direction with at least two Herbert screws.

 

Reported outcomes on type 4 capitellar-trochlear shear fractures are limited. McKee et al21 originally described this pattern and reported on 6 cases.

 

Each case involved an extended lateral Kocher approach and fixation with Herbert screws from an anterior to posterior direction. Good or excellent results were achieved in all cases, with average elbow motion of 15 to 141 degrees, and forearm rotation of 83 degrees pronation, and 84 degrees supination.

 

Ring and Jupiter examined 21 cases of articular fractures of the distal humerus treated with Herbert screw fixation and found 4 excellent results, 12 good results, and 5 fair results.

 

All of the fractures healed and had an average range of motion of 96 degrees. No ulnohumeral instability, arthrosis, or osteonecrosis was reported.

 

 

The authors stressed the importance of proper evaluation of these fractures and awareness that apparent capitellum fractures often are complex articular fractures of the distal humerus.25

 

 

Dubberley et al8 further subclassified type 4 fractures in their series of 28 cases. They achieved an

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average range of motion of flexion-extension of 25 degrees less than the contralateral elbow and 4 degrees of supination-pronation less than the contralateral elbow.

 

Two comminuted cases required conversion to a total elbow arthroplasty.

 

Varied fixation methods were used, including Herbert screws, cancellous screws, absorbable pins, and supplementation with K-wires.

 

 

 

Ruchelsman and colleagues26, 27 reported a case series of 16 patients that were treated with ORIF. All patients achieved full forearm rotation and all but two had functional arc of elbow range of motion. They reported 15 good to excellent results and one fair result.

 

The authors did not find association between concomitant radial head fracture and worse outcomes.

 

Sen and colleagues28 reported internal fixation of isolated trochlear fractures with promising results in a small case series.

 

Comminuted fractures (Dubberley type B) have been shown to be more prone to inferior outcomes complicated by avascular necrosis, degenerative arthritis, and heterotopic ossification.9

 

 

COMPLICATIONS

The most common complication of capitellar fractures is loss of elbow motion and residual pain. The compromised motion most commonly is manifested in loss of flexion and extension.

Ulnar neuropathy has been noted after ORIF, and some recommend routine ulnar nerve decompression.25 This is especially important in capitellar-trochlear shear fractures, as hinging of the elbow on the medial side increases the risk of ulnar nerve compression.

Osteonecrosis may occur from the initial fracture displacement or surgical exposure. Blood is supplied to the capitellum from a posterior to anterior direction and may be compromised by surgical dissection.

In symptomatic cases in which revascularization after fixation has not occurred, delayed excision is indicated.

Malunions may occur when the patient has delayed seeking treatment, when inadequate reduction or loss

 

of closed reduction occurs, or after ORIF. Malunions result in loss of motion and may require excision of

the fragment and soft tissue releases.

Nonunions may occur, although this is uncommon. They most likely result secondary to inadequate reduction or lack of revascularization of the fragment.

 

 

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