Anshu Singh, George Frederick Hatch III, and John M. Itamura
DEFINITION
The radial head is distinctive in anatomy and function with unique considerations regarding the diagnostic and treatment options available to the surgeon.
Radial head and neck fractures are the most common elbow fractures in adults, representing 33% of elbow fractures.
The original Mason classification was modified by Johnson, then Morrey. Hotchkiss proposed that the classification system be used to provide guidance for treatment. It has poor intraobserver and interobserver reliability (FIG 1).9
Type I fractures are nondisplaced and offer no block to pronation and supination on examination.
Type II fractures have displaced marginal segments that block normal forearm rotation. We only include fractures with three or fewer articular fragments, which meet criteria for fractures that can be operatively reduced and fixed with reproducibly good results.
Type III fractures are comminuted or impacted articular fractures that are optimally managed with prosthetic replacement.
Type IV fractures are associated with elbow instability and should never be resected in the acute setting.
ANATOMY
The radial head is entirely intra-articular. It has two articulations, one with the humerus, via the radiocapitellar joint, and another with the ulna, via the proximal radioulnar joint (PRUJ).
The radiocapitellar joint has a saddle-shaped articulation allowing both flexion and extension as well as rotation.
The PRUJ, constrained by the annular ligament, allows rotation of the radial head in the lesser sigmoid notch of the proximal ulna.
To avoid creating a mechanical block to pronation and supination, implants must be limited to a 90-degree arc (the “safe zone”) outside the PRUJ (FIG 2).4
Blood supply to the radial head is tenuous, with a major contribution from a single branch of the radial recurrent artery in the safe zone and minor contributions from both the radial and interosseous recurrent arteries, which penetrate the capsule at its insertion into the neck (FIG 3).13
There is considerable variability in the shape of the radial head, from nearly round to elliptical, as well as variability in the offset of the head from the neck.
The anterior band of the medial collateral ligament (MCL) is the primary stabilizer to valgus stress. The radial head, a secondary stabilizer, maintains up to 30% of valgus resistance in the native elbow. Therefore, in cases where the MCL is ruptured:
A radial head that is not reparable should be replaced with a prosthesis and not excised given its biomechanical importance.
It may be prudent to protect a repaired radial head from high valgus stress during early range of motion by placing a hinged external fixator.
The radial head also functions in the transmission of axial load, transmitting 60% of the load from the wrist to the elbow.10 This is a crucial consideration when the interosseous membrane is disrupted in the Essex-Lopresti lesion.5Resection of the radial head in this setting results in devastating longitudinal radioulnar instability, proximal migration of the radius, and possible ulnar-carpal impingement.
PATHOGENESIS
Radial head fractures result from trauma. A fall on an outstretched hand with the elbow in extension and the forearm in pronation produces an axial or valgus load (or both) driving the radial head into the capitellum, fracturing the relatively osteopenic radial head.
Loading at 0 to 35 degrees of extension causes coronoid fractures.
Loading at 0 to 80 degrees of extension produces radial head fractures.
FIG 1 • The modified Mason classification for radial head fractures.
FIG 2 • The “safe zone” is a roughly 90-degree arc of the radial head that does not articulate with the ulna in the proximal radioulnar joint with full supination and pronation. With the wrist in neutral rotation, the safe zone is anterolateral.
Associated soft tissue injuries can lead to considerable complications, including pain, arthrosis, stiffness, and disability:
MCL injury in 50%
Lateral ligament disruption in about 80%
Capitellar bone bruises in 90%8
Capitellar cartilage defects in about 50%
FIG 3 • A. The radial recurrent artery, a branch of the radial artery, provides the main blood supply to the radial head. B. In most cadaveric specimens, a branch of the radial recurrent penetrates the radial head in the safe zone. (From Yamaguchi K, Sweet FA, Bindra R, et al. The extraosseous and intraosseous arterial anatomy of the adult elbow. J Bone Joint Surg Am 1997;79A:1653–1662.)
The axial loading may also rupture the interosseous membrane, causing longitudinal radioulnar instability with dislocation of the distal radioulnar joint (DRUJ) (FIG 4).
The “terrible triad” injury results from valgus loading of the elbow, disrupting the MCL or lateral ulnar collateral ligament and fracturing the radial head and coronoid process.
NATURAL HISTORY
Results are mixed regarding the efficacy of radial head excision for treatment of radial head fracture. Good or fair results may be possible, with a few caveats:
FIG 4 • A. AP radiograph of the wrist in cases of longitudinal radioulnar instability (the Essex-Lopresti lesion). Subtle shortening of the radius is demonstrated. B. Lateral radiograph of the wrist may show dorsal subluxation of the distal ulna.
There is a demonstrable increase in ulnar variance at the wrist and increased carrying angle.
10% to 20% loss of strength is expected.
It is contraindicated in the face of associated soft tissue injuries.
Radiographic, but usually clinically silent, degenerative changes such as cysts, sclerosis, and osteophytes occur radiographically in about 75% of elbows after radial head excision (FIG 5).
Results of excision are poor in patients with concomitant MCL, coronoid, or interosseous membrane injury.
Radial head resection should be reserved for patients with low functional demands or limited life expectancy, and when the surgeon has excluded elbow instability with a fluoroscopic examination.
Delayed excision of the radial head after failed nonoperative management may be considered with modest increase in function; it has shown 23% fair or poor results at 15 years of follow-up.3 Other studies suggest that there is no difference between delayed and primary excision.6
Although open reduction and fixation of a comminuted fracture can be attempted, a large series by experienced elbow surgeons found that fixation of a radial head with more than three articular fragments is fraught with poor results.11
Nonanatomic reduction of the shaft or joint may result in limited range of motion due to a cam effect in the PRUJ, but no literature or prospective studies indicate what parameters are “acceptable.”
PATIENT HISTORY AND PHYSICAL FINDINGS
The history typically involves a fall on an outstretched hand followed by pain and edema over the lateral elbow, accompanied by limited range of motion.
The examiner should note the patient's activity level and profession.
Physical examination should include neurovascular status and examination of the skin to look for medial ecchymosis, which may suggest injury to the MCL.
A detailed examination of the elbow must include bony palpation of the medial and lateral epicondyles, olecranon process, DRUJ, and radial head, as well as the squeeze test of the interosseous membrane and DRUJ to screen for potential longitudinal instability.
FIG 5 • A CT scan demonstrating symptomatic posttraumatic arthrosis with cyst formation in the ulnohumeral articulation after radial head resection.
FIG 6 • The elbow joint can be aspirated and injected through the posterior and posterolateral approaches. They are equally effective and should be used based on soft tissue injury.
Varus and valgus stress testing, with or without fluoroscopy, can indicate injury to the anterior band of the MCL or to the lateral ulnar collateral ligament, respectively.
Range-of-motion and stress examinations are vital to proper decision making and may obviate the need for advanced imaging if performed correctly with adequate anesthesia. If omitted, this will lead to undiagnosed associated injuries and may result in flawed decision making.
In the emergency department or office, adequate anesthesia may be obtained by aspirating hematoma, then injecting the elbow joint with 5 mL of local anesthetic and examining the elbow under fluoroscopy. This may be performed by the traditional lateral injection in the “soft spot” or posteriorly into the olecranon fossa (FIG 6).12
If operative intervention is clearly indicated, this examination can be performed under a general anesthetic, provided the surgeon and patient are prepared for a change in operative plan as dictated by the examination.
Normal values are 0 to 145 degrees of flexion–extension, 85 degrees of supination, and 80 degrees of pronation. The examiner should check for a bony block to motion.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Radiography
Anteroposterior (AP), lateral, and oblique views are the standard of care, but they underestimate or overestimate joint impaction and degree of comminution (FIG 7A,B).
A radiocapitellar view with forearm in neutral and at 45 degrees cephalad gives an improved view of the articular surfaces.
FIG 7 • A,B. AP and lateral radiographs reveal a type 2 displaced radial head fracture. With standard radiography it is difficult to judge comminution and associated injuries. C. A T2-weighted MR image demonstrating a bony medial collateral ligament avulsion with surrounding edema associated with a radial head fracture. The ligament can be seen inserting distally to the sublime tubercle.
If the examination reveals wrist or forearm tenderness, the examiner should have a low threshold for obtaining bilateral wrist posteroanterior (PA) views to rule out an Essex-Lopresti lesion.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a useful adjunct to physical examination for evaluating associated injuries such as collateral ligament tears, chondral defects, and loose bodies,8 but it is not routinely indicated (FIG 7C).
DIFFERENTIAL DIAGNOSIS
Simple elbow dislocation
Distal humerus fracture
Olecranon fracture
Septic elbow
NONOPERATIVE MANAGEMENT
The standard protocol for treating radial head fractures is shown in FIGURE 8.
FIG 8 • Treatment algorithm for radial head fractures.
FIG 9 • Intraoperative photograph demonstrating the fluoroscopic examination. This is crucial to proper decision making and may be performed just before operative management.
Conservative management, with a week of sling immobilization followed by range of motion once the acute pain resolves, it is the treatment of choice in nondisplaced radial head fractures, where universally good and excellent results have been reported.
Nonoperative management is also the treatment of choice in fractures with less than 2 mm of displacement, with minor head involvement, and without bony blockage to range of motion.
A 7-day period of cast or splint immobilization is followed by aggressive motion after the inflammatory phase.
Our current practice for fractures that are more than 2 mm displaced is to determine whether there is a blockage of motion on fluoroscopic examination.
If there is maintenance of at least 50 degrees of both pronation and supination, we recommend conservative treatment.
If there is a blockage or instability, excision, fixation, or arthroplasty is recommended based on patient factors and instability.
A recent report regarding the long-term results of nonoperative management (similar to that described) of 49 patients with radial head fractures encompassing over 30% of the joint surface and displaced 2 to 5 mm revealed that 81% of patients had no subjective complaints and minimal loss of motion versus the uninjured extremity. Only one patient had daily pain.1
SURGICAL MANAGEMENT
Preoperative Planning
It is essential to review all radiographs and, most importantly, perform thorough history, physical, and fluoroscopic examinations before making an incision.
The presence of instability or associated fractures warrants a more extensile approach (FIG 9).
Positioning
Positioning depends on the planned approach and the surgeon's preference.
We prefer the patient supine with the affected extremity brought across the chest over a bump to allow access to the posterolateral elbow.
A tourniquet is placed high on the arm.
Approach
Two approaches, the extensile posterior (Boyd) and posterolateral (Köcher), will be presented (FIG 10).
The extensile posterior (Boyd) approach2 with an interval between the ulna and anconeus allows for excellent visualization compared to traditional approaches. This versatile approach facilitates ORIF or arthroplasty of the radial head if the fracture proves to be more comminuted than preoperative imaging would predict. It can be easily accessed through a universal extensile incision that allows the surgeon to address ligamentous injuries in addition to the radial head fracture.
FIG 10 • Surgical intervals for the Boyd approach and the Köcher approach.
TECHNIQUES
BOYD APPROACH
An 8-cm straight longitudinal incision is made just lateral to the olecranon (TECH FIG 1A).
Full-thickness skin flaps are developed bluntly over the fascia.
The fascia is longitudinally incised in the interval between the anconeus and ulna (TECH FIG 1B).
The anconeus is dissected off the ulna, elevating proximal to distal to preserve the distal vascular pedicle. Great care is taken not to violate the joint capsule or lateral ulnar collateral ligament by using blunt fashion (TECH FIG 1C).
The lateral ulnar collateral ligament and annular ligament complex are sharply divided and tagged from their insertion on the crista supinatorus of the ulna. The radial head and its articulation with the capitellum are now evident (TECH FIG 1D).
After repair or replacement, the ligaments are repaired to their insertion with suture anchors.
TECH FIG 1 • Boyd approach. A. Make an 8-cm longitudinal incision at the junction of the ulna and anconeus starting about four fingerbreadths distal to the olecranon and extending 2 cm proximal to the olecranon. B. The interval between the ulna and anconeus is incised sharply, with care taken not to violate the periosteum or muscle to minimize the risk of proximal radioulnar synostosis. C. Blunt elevation of the anconeus is crucial to avoid damaging the capsule or lateral ligament complex. D. The capsule and lateral ligament complex are tagged during the approach to facilitate final repair with suture anchors.
KÖCHER APPROACH
The traditional posterolateral (Köcher) approach between the anconeus and extensor carpi ulnaris is cosmetic and spares the lateral ulnar collateral ligament.
We recommend not using an Esmarch tourniquet to allow visualization of penetrating veins that help identify the interval.
A 5-cm oblique incision is made from the posterolateral aspect of the lateral epicondyle obliquely to a point three fingerbreadths below the tip of the olecranon in line with the radial neck (TECH FIG 2A).
The radial head and epicondyle are palpated and the fascia is divided in line with the skin incision.
The Köcher interval is identified distally by small penetrating veins and bluntly developed, revealing the lateral ligament complex and joint capsule (TECH FIG 2B).
The anconeus is reflected posteriorly and the extensor carpi ulnaris origin anteriorly. The capsule is incised obliquely anterior to the lateral ulnar collateral ligament (TECH FIG 2C,D).
The proximal edge of the annular ligament may also be divided and tagged, with care taken not to proceed distally and damage the posterior interosseous nerve.
TECH FIG 2 • Köcher approach. A. The skin incision proceeds distally from the posterolateral aspect of the lateral epicondyle to the posterior aspect of the proximal radius. B. Full-thickness flaps are made and the fascial interval between the extensor carpi ulnaris and anconeus muscles is identified. C. With longitudinal incision of the fascia and blunt division of the muscles, the joint capsule is evident. D. The capsule is longitudinally incised and the fascia is tagged with figure 8 stitches for later anatomic repair.
FRACTURE INSPECTION AND PREPARATION
The fracture is now visible (TECH FIG 3).
The wound is irrigated and loose bodies are removed.
The forearm is rotated to obtain a circumferential view of the fracture and appreciate the safe zone for hardware placement.
If comminution (more than three pieces) is evident at this step, we elect to replace the radial head.
TECH FIG 3 • Here the fractured radial head fragment has violated the lateral capsule, indicating a high-energy injury. The proximal radius is now exposed for fixation or prosthetic replacement.
REDUCTION AND PROVISIONAL FIXATION
Any joint impaction is elevated and the void filed with local cancellous graft from the lateral epicondyle.
The fragments are reduced provisionally with a tenaculum and held with small Kirschner wires placed out of the zone where definitive fixation is planned.
It is acceptable to place this temporary fixation in the safe zone (TECH FIG 4).
TECH FIG 4 • We prefer to use 0.062-inch Kirschner wires placed outside the zone of planned definitive fixation to provisionally hold the reduction.
FIXATION
There are many options for definitive fixation7:
One or two countersunk 2.0-mm or 2.7-mm AO cortical screws perpendicular to the fracture (TECH FIG 5A)
Mini-plates (TECH FIG 5B)
Small headless screws
Polyglycolide pins
Small threaded wires
We prefer to use two small parallel screws for isolated head fractures. For fractures with neck extension, we prefer AO 2.0-mm or 2.7-mm mini-plates along the safe zone.
TECH FIG 5 • A. Two screws are placed in the safe zone perpendicular to the fracture. B. A plate is placed on a radial neck fracture.
CLOSURE
Any releases or injury to the annular ligament or lateral ulnar collateral ligament must be repaired anatomically. Drill holes with transosseous sutures are a proven method, but most authors now use suture anchors with reproducible results.
Skin closure is performed in standard fashion with drains at the surgeon's discretion. Small hemovac drains are routinely pulled on postoperative day 1.
PEARLS AND PITFALLS
POSTOPERATIVE CARE
The elbow is immobilized in a splint for 7 to 10 days.
Active range of motion is allowed as soon as tolerable. Supervised therapy may be considered if the patient is not making adequate progress.
Associated injuries may call for more protected range of motion.
Light activities of daily living are allowed at 2 weeks, with increased weight bearing at 6 weeks.
RESULTS
The results of open reduction and internal fixation depend both on host factors such as the type of fracture, smoking, compliance, demand, as well as surgical and rehabilitation protocols.
In uncomplicated fractures, over 90% satisfactory results can be expected.
Complications and resultant secondary procedures will be more likely in cases with undiagnosed instability and associated injury.
FIG 11 • A. AP radiograph demonstrating a screw penetrating the proximal radioulnar joint. B,C. Although these lowprofile implants were apparently well placed, this patient went on to develop avascular necrosis with fragmentation of the radial head.
COMPLICATIONS
Stiffness is the most common complication, with loss of terminal extension, supination, and pronation being most evident.
Arthritis of the radiocapitellar joint or proximal radioulnar joint
Heterotopic ossification
Symptomatic hardware may require secondary removal (FIG 11A).
Infection
Early and late instability from missed or failed treatment of associated injuries
The rate of avascular necrosis is about 10%, significantly higher in displaced fractures. This is expected given that the radial recurrent artery inserts in the safe zone where hardware is placed. This is generally clinically silent.
Loss of reduction
Nonunion (FIG 11B,C)
REFERENCES
· Akesson T, Herbertsson P, Josefsson PO, et al. Primary nonoperative treatment of moderately displaced two-part fractures of the radial head. J Bone Joint Surg Am 2006;88A:1909–1914.
· Boyd HB. Surgical exposure of the ulna and proximal third of the radius through one incision. Surg Gynecol Obstet 1940;71:86–88.
· Broberg MA, Morrey BF. Results of delayed excision of the radial head after fracture. J Bone Joint Surg Am 1986;68A:669–674.
· Caputo AE, Mazzocca AD, Sontoro VM. The nonarticulating portion of the radial head: Anatomic and clinical correlations for internal fixation. J Hand Surg Am 1998;23A:1082–1090.
· Essex-Lopresti P. Fractures of the radial head with distal radioulnar dislocation. J Bone Joint Surg Br 1951;33B:244–250.
· Herbertsson P, Josefsson PO, Hasserius R, et al. Fractures of the radial head and neck treated with radial head excision. J Bone Joint Surg Am 2004;86A:1925–1930.
· Ikeda M, Sugiyama K, Kang C, et al. Comminuted fractures of the radial head: comparison of resection and internal fixation. J Bone Joint Surg Am 2006;88A:11–23.
· Itamura J, Roidis N, Vaishnav S, et al. MRI evaluation of comminuted radial head fractures. J Shoulder Elbow Surg 2005; 14:421–424.
· Morgan SJ, Groshen SL, Itamura JM, et al. Reliability evaluation of classifying radial head fractures by the system of Mason. Bull Hosp Jt Dis 1997;56:95–98.
· Morrey BF, An KN, Stormont TJ. Force transmission through the radial head. J Bone Joint Surg Am 1988;70A:250–256.
· Ring D, Quintero J, Jupiter JB. Open reduction and internal fixation of fractures of the radial head. J Bone Joint Surg Am 2002;84A: 1811–1815.
· Tang CW, Skaggs DL, Kay RM. Elbow aspiration and arthrogram: an alternative method. Am J Orthop 2001;30:256.
· Yamaguchi K, Sweet FA, Bindra R, et al. The extraosseous and intraosseous arterial anatomy of the adult elbow. J Bone Joint Surg Am 1997;79A:1653–1662.