Fractures of the capitellum represent a distinct subset of coronal plane partial articular injuries of the distal humerus, and account for less than 1% of all elbow fractures. These are coronal shear fractures that may involve the capitellum in isolation, extend medially to involve the trochlea, or occur with complex osseous or ligamentous injuries of the lateral column.
Several classifications have been developed for partial articular fractures of the distal humerus and include those by Ring, Dubberley, and the AO/OTA. The Bryan and Morrey classification is most commonly used (Figure 1). In this system, type I fractures (Hahn-Steinthal) are complete capitellar fractures with little or no extension into the lateral trochlea, type II fractures (Kocher-Lorenz) are anterior osteochondral fractures with minimal subchondral bone, type III fractures are comminuted or compression fractures of the capitellum, and type IV fractures are capitellar fractures that extend medially to include most of the trochlea.
As the complex nature of capitellar fractures has become better appreciated, management options have evolved. Open reduction and internal fixation to achieve stable anatomic reduction and initiate early range of motion is the treatment of choice. Optimal treatment requires an understanding of the complex nature of these injuries, appropriate selection of surgical exposure and fixation, and postoperative rehabilitation of the elbow. Sequelae of these injuries include articular incongruity, posttraumatic arthrosis, stiffness, pain, and instability.
Coronal shear fractures of the capitellum are the result of axial compression to the capitellum by the radial head. Additionally these fractures can occur after a spontaneous reduction of a posterolateral elbow subluxation. Literature suggests a female predominance as a result of the increased carrying angle of the elbow.
Classic Exam Findings
Exam findings include swelling and ecchymosis about the elbow and hemarthrosis. A mechanical block to elbow flexion and painful pronosupination are usually present. Assessment of elbow stability and range of motion is often limited in the acute setting due to pain, and is routinely evaluated under anesthesia at the time of surgical intervention. Laxity to valgus or varus stresses indicates a more complex injury involving medial collateral ligament or lateral ligamentous complex tears, and is important for pre-operative planning. Evaluation of the stability of the distal radioulnar joint is critical to assess for concomitant Essex-Lopresti lesion.
An elbow trauma series including anteroposterior, lateral, and radiocapitellar radiographs should be obtained in addition to ipsilateral forearm and wrist views. The lateral and radiocapitellar radiographs are most valuable, facilitating visualization of the shear fracture. The “double arc” sign is a pathognomonic feature of a capitellar fracture with medial extension through most of the trochlea (type IV), and is seen on a lateral elbow radiograph (Figure 2).
Computed tomography is often used to fully appreciate the complexity of the fracture and define the medial extent of the fracture, articular impaction, and metaphyseal and condylar comminution. These features aid in pre-operative planning with regard to surgical exposure and choice of implants (Figure 3). Ipsilateral fractures of the radial head or neck, olecranon, lateral condyle and epicondyle along with ligamentous injuries or their osseous equivalents may occur in up to 50% of patients. It has been our experience that osteochondral fractures of the capitellum (the type II Kocher-Lorenz variant) commonly occur with radial head or neck fractures and are frequently unrecognized until the time of open reduction. These osteochondral fractures may be unrecognized even with the help of a CT scan.
Non-operative management with closed reduction and/or immobilization is reserved for very ill, low demand patients whose co-morbidities preclude surgical intervention. Immobilization in a long-arm cast or splint with the elbow flexed to 90 degrees for 4-6 weeks to keep the capitellum reduced to the radial head is recommended.
Indications for Surgery
Indications for surgery include isolated displaced, capitellar-trochlear coronal-plane shear fractures of the distal humeral articular surface and capitellar-trochlear shear fractures occurring in association with complex distal humeral fractures and elbow fracture-dislocations with concomitant ligamentous injuries.
Open reduction and internal fixation of capitellar fractures is performed with use of an extensile lateral exposure. This exposure provides sufficient visualization to address medial trochlear extension and comminution in type IV fractures as well as concomitant radial head/neck pathology. When lateral condylar or posterior metaphyseal extension of the fracture is present, this exposure may necessitate elevation of the lateral aspect of the triceps from the posterior distal humerus and proximal ulna. With this exposure, it is critical to preserve both the lateral ulnar collateral ligament and the vascular supply to the capitellum. Should visualization of the trochlea be inadequate with the extensile lateral exposure, a supplemental medial incision with a flexor-pronator split/elevation or a posterior approach with olecranon osteotomy may be necessary.
C-arm/mini C-arm for intra-operative fluoroscopic assessment of fracture reduction.
Headless compression screws (many commercially available types).
Mini-fragment and mini-modular plate/screw systems if supplemental column fixation is needed.
The patient is in supine position with the arm placed on a radiolucent hand table. The patient’s arm is prepped and draped, and a well-padded sterile pneumatic tourniquet is applied.
Step-by-step description of procedure:
Following general or regional anesthesia, the injured elbow is assessed clinically under fluoroscopic guidance for ligamentous stability.
With the elbow flexed, a lateral skin incision at the elbow is centered over the lateral epicondyle. This incision extends from the anterior aspect of the lateral column to approximately 2cm distal to the radial head.
With the forearm in pronation in order to move the posterior interosseous nerve away from the surgical field, the subcutaneous tissue layers are dissected and the lateral column is identified.
The common origin of the radial wrist extensors along with the anterior capsule is elevated and mobilized anteriorly as a full-thickness flap from the lateral supracondylar ridge.
Distally, several deep intervals may be utilized based on the injury pattern. These include Kaplan (interval between the extensor digitorum communis muscle and extensor carpi radialis brevis muscle), Kocher (interval between the aconeus muscle and the extensor carpi ulnaris muscle), and Hotchkiss (medial “over-the-top” approach between the flexor-pronator mass and the flexor carpi ulnaris). The distal interval is connected to the proximal exposure to develop a continuous anterior full-thickness soft-tissue flap. For capitellar fractures with or without fractures of the proximal radius, we prefer a more anteriorly based distal interval to facilitate fracture reduction and fixation.
Intracapsular retractors are placed deep to the brachialis and anterior capsule and over the medial column. This facilitates visualization of the anterior articular fracture segments and radial head/neck (Figure 4).
Once the fracture is adequately visualized and the fracture hematoma evacuated, an anatomic reduction is performed. Impaction of the posterior inferior aspects of the capitellar-trochlear segment requires elevation with or without supplemental bone grafting.
Provisional K-wire fixation is achieved and anatomic reduction is confirmed with orthogonal fluoroscopy.
When there is sufficient subchondral bone on the articular fracture segment, buried cannulated variable pitch headless compression screws are inserted over guidewires in an anterior-to-posterior direction (terminally threaded Hebert screws or fully threaded mini-Acutrak headless screws). Two screws are placed in a divergent pattern in order to control for rotation, and are sufficiently distanced from each other to avoid iatrogenic fracture of the capitellum.
In cases of a Bryan and Morrey type II osteochondral fragment fracture in which there is insufficient subchondral bone for compression screw internal fixation, suture fixation and bioabsorbable implants are also available. Excision is acceptable when there is a pure cartilaginous fragment devoid of subchondral bone, and in this setting the donor site can be treated with chondroplasty.
Supplemental fixation may be required in more complex fracture patterns. Supplemental fixation may include but is not limited to mini-fragment screws, threaded k-wires, and bioabsorbable pins for small osteochondral capitellum and trochlea fragments (Figure 5); lateral column fixation with pelvic reconstruction, precontoured, or locking plates for posterolateral comminution (Figure 6); and suture anchors or transosseous sutures passed through drill holes for a lateral ulnar collateral ligament avulsion or its osseous equivalent.
Pearls and Pitfalls of Technique
Selection of appropriate surgical exposure to address all articular pathology.
Surgical exposure should allow satisfactory visualization of medial extent of fracture to allow for reduction of the trochlea when involved.
Appropriate treatment of concomitant soft tissue injuries.
Underestimation of fracture complexity. Preoperative plain radiographs alone are often inadequate in helping to determine the exact morphology of the fracture. CT images help to define the medial extent of the fracture, articular involvement, metaphyseal comminution, and radial head and/or neck fracture. Concomitant ligamentous disruption, including lateral and/or medial collateral ligamentous complexes, or their osseous equivalents must be recognized and repaired for optimal outcomes.
Inadequate exposure of the radiocapitellar compartment and visualization of the medial extent of articular fracture.
Failure to restore articular congruity.
Failure to recognize posteroinferior metaphyseal comminution, which may require a cancellous allograft.
Potential for ulnohumeral instability if the trochlea-olecranon articulation is not restored.
Iatrogenic injuries to the lateral ulnar collateral ligament or posterior interosseous nerve.
Prolonged postoperative immobilization.
Several complications following fixation of capitellar fractures exist. These include stiffness, loss of fixation, pain, instability, and neurologic dysfunction. Even with early mobilization following open reduction and internal fixation, post-traumatic stiffness is seen in up to 40% of patients. The literature suggests good to excellent outcomes after open reduction and internal fixation of fractures of the capitellum and trochlea. In patients with type IV fractures, a functional arc of ulnohumeral motion (30 – 130 degrees) is achieved in most patients following open reduction and internal fixation, despite a mean postoperative flexion contracture of 14.5 – 17.5 degrees. In cases when a functional range of ulnohumeral motion is not achieved, extension splinting, physical therapy, and contracture release have been found to improve range of motion.
Ulnar neuropathy following elbow trauma is well-described and may due to the initial mechanism of injury, iatrogenic injury, or post-traumatic scarring and tethering within the cubital tunnel. Ulnar nerve decompression with or without transposition is recommended when secondary contracture release is performed. Literature reports a variable range of mild to moderate post-traumatic degenerative changes following partial articular fractures of the distal humerus from 0 – 32%. Additional studies are needed to more fully evaluate the incidence of post-traumatic arthritis following these fractures because of the paucity of literature reporting long-term outcomes.
The patient should be non-weight bearing in the operative upper extremity.
When rigid fixation is achieved, a long arm posterior plaster splint or compressive dressing is placed and is removed at the first office visit about 7 – 10 days postoperatively. When fixation is suboptimal, delayed or protected mobilization with a hinged elbow brace may be required. In the presence of a concomitant ligamentous injury, a ligament-specific protocol is undertaken, with mobilization in pronation (lateral-sided injury) or supination (medial sided injury).
Important timepoints for advancement of activities:
After the first postoperative office visit, active and active-assisted elbow range of motion is initiated. Strengthening exercises and/or static splinting for contracture are started once there is evidence of fracture union, which is usually around 6 weeks postoperatively.
Outcomes/Evidence in the Literature
Dubberley, JH, Faber, KJ, Macdermid, JC, Patterson, SD, King, GH. “Outcome after ORIF of capitellar and trochlear fractures”. J Bone Joint Surg Am. vol. 88. 2006. pp. 46-54. (Review of 28 patients treated with ORIF for capitellar and trochlear fractures with a description of fracture patterns and functional outcomes. Also proposed a novel treatment and outcome based classification.)
Elkowitz, SJ, Polatsch, DB, Egol, KA, Kummer, JF, Koval, KJ. “Capitellum Fractures: A biomechanical evaluation of three fixation methods”. Jour Orthop Trauma. vol. 16. 2002. pp. 503-6. (Evaluated the relative stability of three fixation methods for displaced fractures of the capitellum from twelve matched cadaver humeri. Found that headless compression screws were more stable than posteroanteriorly directed cancellous lag screws, which were more stable than anteroposteriorly directed screws.)
McKee, MD, Jupiter, JB, Bamberger, BH. “Coronal shear fractures of the distal end of the humerus”. J Bone Joint Surg. vol. 78-A. 1996. pp. 49-54. (Review of shear fractures of the distal articular surface of the humerus that extended in the coronal plane across the capitellum, lateral trochlear ridge, and lateral half of the trochlea. Emphasized that many capitellar fractures extend across much of the trochlea.)
Ring, D, Jupiter, JB, Gulotta, L. “Articular fractures of the distal part of the humerus”. J Bone Joint Surg Am. vol. 85. 2003. pp. 232-8. (Reviewed 21 patients with distal humeral articular fractures and analyzed the results following ORIF. Developed a novel fracture classification in which there are 5 types, each of increasing severity.)
Ring, D. “Open reduction and internal fixation of an apparent capitellar fracture using an extended lateral exposure”. Jour Hand Surg. vol. 34A. 2009. pp. 739-743. (Detailed the extended lateral exposure, one of the most common approaches for both simple and complex fractures of the capitellum.)
Ruchelsman, DE, Tejwani, NC, Kwon, YW, Egol, KA. “Coronal plane partial articular fractures of the distal humerus: current concepts in management”. J Am Acad Orthop Surg. vol. 16. 2008. pp. 716-728. (Review of coronal plane particular articular fractures of the distal humerus, including detailed descriptions of fracture evaluation, classification, and management options. Full literature review with outcomes of published retrospective cohort series following ORIF of capitellum and trochlea fractures.)
Ruchelsman, DE, Tejwani, NC, Kwon, YW, Egol, KA. “Open reduction and internal fixation of capitellar fractures with headless screws”. J Bone Joint Surg Am. vol. 90. 2008. pp. 1321-9. (Evaluation of the clinical, radiographic, and functional outcomes following ORIF of capitellar fractures treated with a uniform surgical approach in 16 patients. Video supplementation is available.)
Fractures involving the capitellum and trochlea represent significant articular injuries that may occur in isolation, or as part of more complex periarticular elbow trauma. As the complex nature of these injuries has become better appreciated, a preference for open reduction and internal fixation has become the treatment option of choice. Fracture classification, surgical exposure, and selection of internal fixation techniques are based on fracture pattern, articular and ligamentous involvement. Variable pitch, headless cannulated compression screws positioned in an anterior–to-posterior direction buried beneath the articular surface have become the implant of choice for simple fracture patterns. More complex fracture patterns may require extensile approaches, the addition of lateral column plating, mini fragment screws, or ligamentous repair to obtain a stable, functional, and painless elbow.
Clinical series reporting outcomes following open reduction and internal fixation of fractures of the capitellum, with or without associated injuries, have reported good-to-excellent results with functional ulnohumeral motion. Patients with more complex injuries must be counseled about the potential for limited ulnohumeral arc of motion and post-operative flexion contracture. Clinically significant osteonecrosis and heterotrophic ossification are rare, but mild to moderate post-traumatic osteoarthritis may be anticipated at follow-up.
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