Capitellar Fractures


Background

Fractures of the capitellum are rare but may be more complex and extensive than is apparent from conventional radiographs. [1The complete capitellar fracture pattern was first described in 1853 by Hahn and Steinthal; the eponym for this fracture pattern includes their names. Later, Kocher and Lorenz described an additional variation of this fracture pattern; a classification system includes their names.

Because of the rarity of capitellar fractures, controversies exist regarding the most appropriate treatment. [2The fracture fragment is intra-articular and requires treatment and reduction to reestablish normal elbow motion. Difficulty arises from the varying size of the fracture fragment and from the varying amount of suitable subchondral bone that is present to achieve stable fixation and to allow early elbow motion. Failure of adequate intervention may result in an incongruous joint, as well as in stiffness, instability, and chronic pain.

For patient education resources, see the First Aid and Injuries Center, as well as Broken Arm and Broken Elbow.

Etiology

Fractures of the capitellum occur in the coronal plane. Separating the capitellum from the lateral column, capitellar factures are the result of shear forces from a fall onto the outstretched hand or of a fall directly onto the elbow. The capitellum is susceptible to shear forces because its center of rotation is 12-15 mm anterior to the humeral shaft.

Capitellar fractures may be associated with radial head fractures and posterior dislocations of the elbow. Other associated injuries include the disruption of the medial (ulnar) collateral ligament, the interosseous membrane, and the distal radioulnar joint.

Epidemiology

Capitellar fractures account for 0.5-1% of all elbow fractures and 6% of all distal humeral fractures. [3Capitellar fractures are seen with greater frequency in females than in males; this is thought to be secondary to a greater carrying angle and an increased possibility of osteoporosis in females. In 20% of patients with capitellar fractures, radial head fractures also are found. [4]

Capitellar fractures do not occur in children younger than 10 years. Because of the cartilaginous composition of the capitellum in children, a similar injury in a child would be a supracondylar or lateral condylar fracture.

Prognosis

Although some authors have advocated fragment excision, a study by Grantham et al demonstrated unsatisfactory results at 5-year follow-up. [5The greatest complaint was stiffness and instability. In the same study, more favorable results were seen with open reduction and internal fixation (ORIF).

McKee et al also demonstrated improved results with early ORIF, along with early motion. [6A 125º flexion-extension arc was achieved.

Despite the presence of greater flexion contractures at the time of follow-up in elbows with type IV fractures or fractures with an ipsilateral radial head fracture, good-to-excellent outcomes with functional ulnohumeral motion can be achieved following internal fixation of these complex fractures. [7]

Nonoperative and operative management of isolated capitellar fractures leads to satisfactory clinical outcomes as determined by postoperative range of motion (ROM), improvements in pain, and a return to previous levels of function. [8No statistical difference in outcomes was observed between patients undergoing operative management and those undergoing closed reduction and immobilization

Ashwood et al presented the results of treatment of capitellar fractures in 26 patients who were followed prospectively and treated within a week of the injury. [9According to the Mayo Elbow Performance Index (MEPI), nine patients had excellent results, nine had good results, and eight had fair results. Poorer outcomes were associated with posterior comminution of the humerus requiring more extensive procedures. All patients were able to return to work within 6 months, but six changed work roles from manual to administrative work.

Ruchelsman et al evaluated clinical, radiographic, and functional outcomes after ORIF of capitellar fractures in 16 patients. [7Extensile lateral exposure and articular fixation with buried cannulated variable-pitch headless compression screws was performed at a mean of 10 days after injury. Injuries consisted of six type I, two type III, and eight type IV fractures according to the Bryan and Morrey classification (see Classification). Supplemental minifragment screws were used in four of the type IV fractures and in one of the type III fractures. Mean ulnohumeral motion was 123º (range, 70-150º).

Functional arc-of-elbow motion was achieved in 16 patients, and all patients had full forearm rotation. [7Mean MEPI score showed nine excellent results, six good results, and one fair result. Patients with type IV fractures had greater magnitude of flexion contracture, reduced terminal flexion, and reduced net ulnohumeral arc.

Guitton et al studied 30 partial articular fractures involving the capitellum and trochlea. [10One or more subsequent surgical procedures were required in 18 patients (67%), eight of which were for surgical complications. Routine removal of implants occurred in 15 patients. In addition to the fracture of the distal part of the humerus, four patients had an elbow dislocation; three had a fracture of the olecranon or the proximal part of the ulna; and two had a fracture of the radial head. The majority of capitellar fractures in this study turned out to be complex fractures of the articular surface involving both the capitellum and the trochlea.



History

The patient is usually elderly or middle-aged and presents following a fall onto an outstretched extremity or following direct trauma to the elbow. The primary complaints are as follows:

  • Pain
  • Swelling
  • Decreased elbow range of motion (ROM)

Physical Examination

Pain, swelling, and tenderness that are localized to the lateral elbow are evident on physical examination. Any attempt at flexion or extension motion is resisted, and the pain is accentuated with forearm rotation. Examination of the shoulder and wrist is mandatory to exclude associated injuries.



Imaging Studies

Standard anteroposterior (AP) and lateral radiographic projections should be obtained. In most instances, these will demonstrate the fracture. In type II fractures, a radial head–capitellum view may be useful in assisting in subchondral bone visualization. Radiographs of the shoulder or wrist should be obtained if the patient has any complaints of pain or tenderness on examination. Capitellar fractures may be associated with radial head fractures and posterior dislocation of the elbow.

Linear tomography and computed tomography (CT) sometimes may be necessary to achieve better delineation of the fracture pattern and the amount of subchondral bone present.

Classification

Capitellar fractures have been conventionally classified as types I and II, but a more extensive and descriptive classification system, the Bryan and Morrey system, [11 has also been developed and is now in common use.

The conventional classification includes the following types:

  • Type I (Hahn-Steinthal fracture) - Complete fracture with a large osteochondral fragment that is equivalent to the entire capitellum
  • Type II (Kocher-Lorenz fracture) - Thinner, more superficial layer of subchondral bone with attached cartilage; rarely, a complete-thickness, chondral-shearing fragment is present and may be difficult to identify on radiographs
  • Type III - Comminuted capitellar fracture

The Bryan and Morrey classification system includes the following types [11:

  • Type I - Complete osteochondral fracture of the capitellum
  • Type II - Superficial osteochondral fracture fragment
  • Type III - Comminuted fracture fragment
  • Type IV - Coronal shear fracture described by McKee et al, involving the capitellum and a portion of the trochlea [610]

Another classification, the Dubberley system, stratifies these injuries into three types, each of which has A and B subtypes, as follows [12:

  • Type 1 - Fracture of capitellum with or without lateral trochlear ridge: (A) without posterior condylar comminution; (B) with posterior condylar comminution
  • Type 2 - Fracture of capitellum and trochlea as one piece: (A) without posterior condylar comminution; (B) with posterior condylar comminution
  • Type 3 - Fracture of capitellum and trochlea as separate pieces: (A) without posterior condylar comminution; (B) with posterior condylar comminution.


Approach Considerations

Treatment of capitellar fractures is similar to that of any intra-articular fracture. Every effort should be made to repair and stabilize displaced capitellar fractures. However, should a significant amount of comminution be present, fixation may not be possible, and excision of the fragments may prove necessary instead. No contraindications for surgical treatment exist, other than those imposed by the patient's medical status, ability to tolerate anesthesia, and activity level. (See Surgical Therapy.)

The development of smaller screws and absorbable implants has led to more successful results with open reduction and internal fixation (ORIF). All efforts should be made to reduce a displaced capitellar fragment, whether by closed or by open techniques.

Closed reduction can be attempted for type I fractures (see Medical Therapy). However, soft-tissue attachments are rare, and stability allowing early motion may not be achieved. The most appropriate treatment of type I capitellar fractures is ORIF. If closed reduction is unsuccessfully attempted, open reduction is indicated.

Open reduction is indicated in all displaced fractures of the capitellum and in those for which closed reduction fails. The presence of significant comminution may preclude fixation; surgical excision of the comminuted fragments is then recommended.

With the evolution of smaller implants, absorbable implants, and biologic surgical techniques, more aggressive attempts at fixation of capitellar fractures will continue to be made. Arthroscopically assisted reduction and percutaneous fixation will also be options.

Medical Therapy

Closed reduction can be attempted for type I fractures (see Classification) with the patient under general anesthesia, as described by Ochner et al. [13The elbow is extended, distracted, and gently flexed in an attempt to capture the fragment and lock it into place. The elbow is manipulated with fluoroscopic assistance (or permanent radiographs may be obtained to confirm reduction). Closed reduction is best performed under muscle-relaxing anesthesia with fluoroscopic control.

Attempts should not be repeated, to avoid additional damage or comminution of the fragment. Should the reduction be unsuccessful or nonanatomic, open reduction is indicated.

Surgical Therapy

Surgical techniques and implants have evolved to the point where fixation of small fractures is feasible and reproducible. The literature supports anatomic reduction and the initiation of early motion as the treatment of choice for capitellar fractures. Efforts should be made to reduce and stabilize displaced fractures that block extension. When an attempt at closed reduction is unsuccessful, immediate progression to open reduction is recommended. [714815 The choice of surgical approach may be influenced by the pathoanatomy of the particular fracture. [16]

Preparation for surgery

Preoperative planning involves the following steps:

  • Review the anatomy and the surgical approach between the anconeus and the extensor carpi ulnaris
  • Have radiographs present in the operating room
  • Use a radiolucent hand table
  • Use a fluoroscope (C-arm)
  • Ensure that the following items are available: minifragment standard screw set, Kirschner wires (K-wires), small/minifragment Herbert screws, absorbable pins, and prophylactic antibiotics (usually 1 g cephalosporin)
  • Apply a tourniquet

Operative details

Position the patient supine on the operating room table, and place the injured extremity on the radiolucent hand table. Perform standard extremity preparation and draping. Flex the elbow. Exsanguinate with an Esmarch bandage, 200-250 mm Hg.

Use a lateral approach to the elbow, between the anconeus and the extensor carpi ulnaris. Begin the incision 2 cm proximal to the lateral epicondyle, and extend it 2-3 cm distal to the radial head.

The common extensor origin can be osteotomized from the lateral epicondyle or incised longitudinally with minimal subperiosteal elevation of the origin. Expose the lateral elbow joint. Avoid posterior dissection. Be aware of the course of the radial nerve between the brachioradialis and the brachialis. An extensile lateral exposure can also be used. [7 Vaishya et al reported good results with ORIF done via an anterolateral approach with headless double-threaded compression screws. [17]

Irrigate the joint. The fracture fragment often has no soft-tissue attachments. Reduce the fracture fragment, and temporarily secure it with K-wires.

Internal fixation options include the following:

  • Herbert screws [18or headless compression-type screws [7inserted through the articular surface
  • Countersunk 2.0-mm minifragment interfragmentary compression screws
  • Standard or cannulated minifragment interfragmentary compression screws placed posteriorly, with care taken to avoid significant posterior dissection
  • Absorbable pins for type II and III fractures, placed as needed
  • Excision if the fragment is too small or comminuted

Check the range of motion (ROM) and the fracture stability. Reattach the origin of the common extensor tendons.

Release the tourniquet; achieve hemostasis. Close the wound.

Apply a removable posterior splint. If the fixation is stable, institute early motion; if it is less stable, delay ROM (3-4 weeks).

Postoperative Care

Check neurovascular status in the recovery room. Place ice on the lateral elbow. Instruct the patient regarding limb elevation.

Complications

As with any osteochondral fractures and with intra-articular fractures in general, complications of treatment include the following [19:

Loss of ROM may arise from closed reduction with immobilization and, often, from surgical excision of the fragment.

As a consequence of the rapid revascularization of the fragment, AVN occurs more often than is recognized. Should the avascular fragment become symptomatic, delayed excision is recommended.

Malunion is uncommon and is often caused by delayed identification by the patient and the physician. When malunion occurs, elbow flexion is usually severely restricted. Anterior elbow soft-tissue release and fragment excision are indicated. Yu et al described the use of arthrolysis, late internal fixation, and a hinged external fixator to treat patients with a stiff elbow associated with malunion or nonunion after delayed treatment of capitellar fracture. [20]

Nonunion may be isolated or may be associated with AVN. If the fragment is large enough and viable, an attempt at refixation may be made. If the fragment is small and symptomatic, excision is indicated. In treating these complications, an anterior capsular release in conjunction with the proposed procedure should be considered.

The results of one study concluded that patients with operatively treated comminuted fractures of the capitellum and trochlea have a greater risk of nonunion than other types of capitellum and trochlea fractures, notably when a posterior comminution is noted (Dubberley type 3B) and multiple articular fragments are created. [21]

Long-Term Monitoring

Depending on the fixation achieved, the patient should be scheduled for physical therapy for progressive and protected single-plane elbow motion. A plastic, removable splint may be made.

The follow-up schedule with the physician, with radiographs at each visit, is as follows:

  • 7-10 days
  • 14-20 days
  • 4-6 weeks
  • 3 months
  • 6-12 months

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