Although radial head fractures comprise a very common injury in everyday clinical practice, their proper management remains difficult and controversial. Radial head fractures often are misdiagnosed because symptoms are similar to elbow sprains; they usually result from a fall onto the outstretched hand. This type of fracture may be isolated or associated with more complex injuries such as fractures and dislocations around the elbow, soft-tissue injuries, and rupture of the distal radioulnar joint.
Incidence and Mechanism of Injury
Radial head fractures may be the result of indirect trauma and constitute approximately one third of all fractures and elbow dislocations. Radial head fractures are involved in approximately 20% of elbow trauma cases1,2 and 5%-10% of elbow dislocations are associated with a radial head fracture.3,4 Eighty-five percent of fractures occur in adults aged between 20 and 60 years (mean age: 30-40 years) and the ratio between males and females is approximately 1:2.1
Undisplaced or minimally displaced fractures represent 40%-60% of all the fracture types seen.5 The usual scenario for a radial head fracture is a fall with the arm abducted and the elbow between 0° and 80° of flexion as shown by Amis and Miller.6 The force of the fall at the time of injury is of varying value and is resulting in a valgus pronation force that is transmitted across the proximal radius to the elbow. The radial head is pushed against the capitellum and may be split or broken. The articular cartilage of the capitellum may be bruised or chipped, resulting in an injury not only to the radial head, but also to the capitellum.
Occasionally, a fracture of the radial head may be a result of a valgus force to the elbow, and the injury also may become complicated by a fracture of the olecranon.7 A direct blow also could cause a radial head fracture, but this is considered uncommon.6 Although radial head fracture may be an isolated lesion, the displaced and often comminuted radial head fracture can frequently be associated with a fracture of the coronoid process, a torn medial collateral ligament (MCL) that renders the elbow joint completely unstable to valgus stress, and/or an injury to the interosseous membrane and the triangular fibrocartilage complex, causing axial instability of the forearm with subluxation of the distal radioulnar joint (Essex-Lopresti dislocation).1,8
Validity of classification schemes
The optimal classification for a given injury should fulfill the following requirements:
- to be simple and concise,
- to be practical,
- to provide accurate consecutive levels of severity,
- to be easily memorized,
- to provide treatment guidelines, and
- to provide prognostic characteristics.
Mason2 and/or Mason-Johnston9 classifications are purely radiographic and have been proven insufficient to guide clinical treatment. Morgan et al10 demonstrated a poor reliability of classifying radial head fractures by Masons system. Additionally, Morrey4 reported that this classification is particularly useful for simple (uncomplicated) radial head fractures. If the fracture is complex, the treatment plan is based on the associated injury.1,4,5 However, it has been traditionally used to characterize radial head fractures.
Mason Type I is an undisplaced fracture; Type II, displaced, with involvement of >30% of the head and usually lower than its half; and Type III, a comminuted fracture involving the entire head. Johnston9 has added the Type IV category, which characterizes a concurrent radial head fracture and an ulnohumeral dislocation. Although the radial head fracture classification is a simple radiographic evaluation, the optimal classification that would relate to various treatment protocols and prognosis has yet to be established.
Mason in his classification did not include associated injuries, presenting as an acute mechanical block, or tears of the interosseous membrane of the forearm that may influence the treatment and the final outcome after a radial head fracture. For that reason, many authors have attempted to propose modifications based on the physical signs and the associated injuries, beyond the pure radiographic fracture patterns.
The Hotchkiss11 modification includes clinical examination and provides guidelines for the treatment of such injuries.
The Schatzker and Tile7 classification divides radial head fractures into three types:
- Type I: split-wedge fracture,
- Type II: impaction fracture, and
- Type III: severely comminuted fracture.
The AO classifies12 the different fracture patterns into simple (21-B2.1), multifragmentary without depression (21-B2.2), and multifragmentary with depression (21-B2.3). Although this classification is good for coding purposes, it is not very helpful for daily practice and does not indicate the severity of the articular head fracture.7
Morrey reported one additional level of classification (Mayo classification) that can be expressed in several ways: uncomplicated and complicated; simple and complex; or with or without associated injury.1 The additional injury in complicated fractures may either be another fracture or ligament injury or both. Complicated injury patterns about the elbow joint are considered as complex elbow instability.
Associated Injuries and Complicated Radial Head Fractures
The degree of ligamentous injury that occurs with a radial head fracture is not always fully appreciated. Previous investigators have reported various results with regard to the incidence of associated bony or ligamentous injuries.1,8 The combination of a radial head fracture with attenuation or MCL tear has been reported to occur in 1%-2% of patients.1
| || |
Figure 1: MRI demonstrating a radial head fracture with a concomitant bone bruise at the capitulum humeri.
Roidis et al13-16 reported on the results of an MRI evaluation of 24 consecutive patients with an acute radial head fracture (Mason type II & III) without documented dislocation or tenderness at the distal radioulnar joint. The evaluation was done with elbow anteroposterior (AP) and lateral radiographs and magnetic resonance imaging (MRI) performed with the patient in a splint in sagittal, coronal, axial, axial oblique, and coronal oblique planes.17 The authors investigated the integrity of both the MCL and lateral collateral ligament, the presence of capitellar osteochondral defects or bone bruises and loose bodies. The MRI evaluation of the participants in this study revealed a high percentage of ligamentous injuries. The incidence of associated injuries was: MCL not intact, 13/24 (54%); lateral collateral ligament not intact, 18/24 (80%); both collateral ligaments not intact, 12/24 (50%); capitellar osteochondral defects, 7/24 (29%); capitellar bone bruises, 23/24 (96%); and loose bodies, 22/24 (92%).
The results of this study clearly showed a high incidence of osteochondral and ligamentous injuries in radial head fractures initially presented as uncomplicated that question the validity of the radiographic classification systems (Figure 1). Radial head fractures that initially present as uncomplicated-displaced or comminuted (Mason type II and III) may have associated ligamentous injuries that dramatically alter the classification, prognosis, and appropriate treatment protocols.
The cost per MRI examination is very high and is not recommended as part of routine preoperative work-up. It is necessary to perform a detailed clinical and radiographic examination in every comminuted radial head fracture. Careful intraoperative examination under fluoroscopy may be helpful in determining the presence of associated ligamentous injuries.
Due to the high incidence of intra-articular loose bodies, careful intraoperative evaluation and irrigation of the joint should be performed. A high level of suspicion should be used when treating this type of fracture because concomittant osseous, osteochondral, and ligamentous injuries might be present. In that way an uncomplicated fracture may be a complicated fracture leading to elbow instability that can be very easily misdiagnosed.
Radial Head Fractures
Herbertsson et al18 reported on a long-term follow-up study aiming at the evaluation of the incidence and the long-term results of closed uncomplicated Mason type II and III fractures in a defined population of adults. Seventy women and 30 men who were a mean age of 47 years when they sustained a fracture of the radial head or neck (a Mason type II fracture in 76 patients and a Mason type III fracture in 24) were re-examined after a mean of 19 years. They reported predominantly favorable results as 77 patients had no symptoms in the injured elbow at follow-up, 21 had occasional pain, and 2 had daily pain. The injured elbows had a slight flexion deficit compared with the uninjured elbows (mean and standard deviation, 138°±8° compared with 140°±7°) as well as a small extension deficit (mean and standard deviation, 4°±8° compared with 1°±6°) (P<.001 for both).
Good long-term results for uncomplicated radial head fractures are reported in the previously reported study while the authors reported that there were no associated soft-tissue injuries. Most of the reported injuries (77 of 100) were the result of low-energy trauma. Additionally, no information provided focused on possible instability issues on initial clinical examination.16 Furthermore, two letters to the editor were published concerning the results of the previously cited study.19,20 The first by Ring19 who among others reported that: Displaced fractures are often associated with other fractures or ligament injuries of the elbow or forearm. This makes sense, given that substantial displacement of the radial head would by necessity be associated with substantial displacement of either the forearm or elbow articulation and this would indicate some degree of injury to the structures that stabilize these joints. Some authors have cautioned that all, or nearly all, complex fractures of the entire radial head (Mason type 3) will be part of a more complex injury pattern. It can be difficult to detect associated injury to the elbow or forearm when treating fractures of the radial head. The second was by Hausman and Mullett20 who, among others, reported that, There is increasing evidence that displaced radial head fractures are frequently associated with associated ligamentous injury. Indeed there is growing skepticism that a displaced radial head fracture can occur in the absence of concomitant medial or lateral collateral ligament injury.
Biomechanical studies have clarified the key role of the medial collateral ligament particularly in radial head fracture or excision. Poor outcomes from treatment of radial head fractures without addressing associated injuries have been reported. The superior results reported by Herbertsson et al18 are at odds with these reports and our personal experience. To combine type II and III fracture groups in a single analysis gives a misleading impression of a benign injury with almost universal good outcome.
Most radial head fractures can be diagnosed with standard radiographic evaluation with anteroposterior and lateral projections of the elbow. The direction of the x-ray beam in AP projection must be perpendicular to the radial head because the elbow joint can rarely be extended.21 The radiographic evaluation may reveal a vertical split or a single fragment of the lateral portion of the head usually displaced distally or multiple fragments of the radial head. The radial head-capitellum view can be useful in identifying fractures of the posterior half of the radial head22 or in a fat pad sign that refers to intra-articular hemarthrosis and sometimes is the only visible radiographic sign in an undisplaced radial head fracture. An additional radiographic evaluation of the wrist should be made if pain is present to exclude injury of the distal radioulnar joint. Although concomitant injury to the capitellum (bruised or chipped) is an important complication, it cannot be established radiographically. Tomograms or computed tomography (CT) scans about the elbow joint may be useful in defining the comminution and the degree of displacement especially when open reduction and internal fixation is considered.
Although radial head fractures are considered a relatively benign injury, their treatment is of great importance and has developed over the years by using various techniques and methods.1,11,21,23 The principal goal of treatment is to maintain good elbow function and thus to retain adequate motion and joint stability. In general, the treatment of radial head fractures is based on the fracture type and the presence of any associated injury (complicated/uncomplicated fractures).1,11,21,23
Type I Fractures
There is no doubt that radial head fractures with no or minimal displacement should be treated conservatively. The only concern in patients treatment must be early motion, as early as tolerated. The early motion is helpful to maintain the shape and molds slight incongruities without risk of further displacement.11,21,23 Aspiration followed with or without instillation of local anesthetic into the elbow joint helps to decompress the joint from hematoma. Additionally, it reduces the pain and allows the joints range of motion (ROM) evaluation identifying the presence of bony blocks. Holdsworth et al24 found that aspiration, although a safe procedure in improving the initial ROM and pain relief, did not alter the final outcome.
Several positions of immobilization have been advocated for the treatment of these fractures. Thompson25 and Unsworth-White et al26 in their study compared flexion versus extension splinting in the treatment of Mason type I fractures. Both authors showed that splinting in full extension is better than 90° of flexion. The loss of extension in their group of patients was <10° in comparison with the other groups.
Patients with type I fractures generally obtain good to excellent restoration of elbow function after 2 to 3 months of active motion exercises. Early motion compared with prolonged immobilization appears to offer advantages in elbow function.1,11,21,23 Early motion should be restricted for fractures that involve less than one third of the articular surface in the elderly or low-demand individuals. Active patients with undisplaced fractures involving more than one third of the articular surface should be splinted for a minimum of 2 weeks, followed by protected motion for an additional 7 to 10 days.23 Good results in type I fractures can be expected in 86%-100% of patients.5,27 Minimal loss of elbow extension and forearm rotation is not uncommon, but the loss rarely affects arm function. Contracture, occasional pain, and inflammation are uncommon. Displacementfollowing or not early motionand nonunion are rare and are treated by osteosynthesis or delayed excision of the radial head. Sometimes, osteochondral fracture of the capitellum may be responsible for a poor result in type I fractures.11
| || |
| || |
Figure 2: AP (A) and lateral (B) radiographs demonstrating a type-I radial head fracture associated with a fracture of the capitellum. Postoperative AP (C) and lateral radiographs (D) of the same patient treated with open reduction and internal fixation.
Type II Fractures
Early studies advocated either conservative management or excision of the radial head as the standard treatment for type II fractures.1,11,23 As knowledge increased, the understanding of the functional importance of the radial head as a secondary stabilizer to valgus stress and as an axial weight bearing structure led to the better understanding of its biomechanics, and dictated treatment options. Currently, a variety of techniques have been developed based on the specific type (degree of displacement) of fracture being treated, but the final choice of treatment is still controversial (Figure 2).
The evaluation of the mechanical block is highly important for the final treatment decision, as not all of the marginal displaced fractures require internal fixation.4,28 Minimally displaced or undisplaced Mason type II fractures can be managed conservatively in a manner similar to that of type I fractures. Surgery is not advisable in the presence of 70° of active pronation and supination regardless of the radiographic findings.29 If displacement occurs despite immobilization, a delayed radial head excision can be performed from 1 month to 20 years with 77% good or excellent results.30 Acute mechanical block in displaced type II fractures is best treated by open reduction and internal fixation especially in young and active individuals. Preservation of the radial head should always be considered when associated injuries about the elbow and the forearm are present. Treatment options include open reduction and internal fixation, excision of the fragments, excision of the radial head and prosthetic radial head replacement.
Open Reduction and Internal Fixation
Currently internal fixation has become popular (Figures 2 and 3), since contemporary techniques have improved surgical outcomes.21,31,32 AO mini-screws and mini-plates, (Synthes, Paoli, Pa), Herbert screws (Zimmer, Warsaw, Ind), and absorbable polyglycolide pins are used for the restoration of the fractured radial head and neck.21,31-33 The indications and contraindications for open reduction and internal fixation are shown in Table 1. An insertion of one or two 2.0- or 2.7-mm AO cortical mini-screws parallel to the radiohumeral joint can easily fixate isolated large fragments, by using a posterolateral oblique approach to the elbow. Screw heads are countersunk and care should be taken that the screw tips do not protrude out the articulating portion of the radial head. Impacted fractures of the head often require elevation to restore the articular surface. The defect beneath the elevated fragment is best filled with cancellous bone graft from the lateral epicondyle of the humerus.23
Hardware placement for the fixation of radial head fractures should not affect the proximal radioulnar joint. The non-articulated portion of the radial head is referred to as the safe zone. The safe zone region corresponds to approximately 110° of radial head surface. According to Hotchkiss,11 it is estimated intraoperatively by reference marks onto the radial head during forearm rotation. Caputo et al34 defines this zone as a portion of the radial head that lies between perpendicular axes through the radial styloid and Listers tuberosity.
Herbert screws can be used for radial head fractures alone, without extension of the fracture line to the radial neck as they provide a reliable and effective fixation.33 Another treatment option is the use of absorbable polyglycolide pins.3,35 The partial excision of a displaced fragment, although advocated in the past,1,21,23 is currently not being used because it can lead to subluxation of the remaining radial head.1,5
When fractures are extended to the radial neck, a mini AO plate (2.0-2.7 mm) can be used to secure the head to the shaft of the radius (Figure 3). In a comminuted radial neck fracture along the medial side, bone grafting should be considered to support the radial neck.36 When there is no concomitant fracture of the radial head, the use of an intramedullary pin is advisable.37 Patterson et al38 reported the results of a comparative study between different plates for the fixation of radial neck fractures. They concluded that the two important variables affecting construct stiffness are plate thickness and incorporation of a fixed-angle plate. The optimal position for the placement of the plate in complex fractures of the proximal radius associated with neck dissociation is the direct lateral position in neutral rotation.39
The postoperative care in type II fractures must be individualized. Normally, a posterior splint in neutral rotation is used either in full extension5 or in 90° of flexion.1 The immobilization period usually is 1-2 weeks.40 Painless active ROM is permitted as soon as tolerated. The allowance of mobilization and the ROM must be made with respect to concomitant injuries. Patients must be directed to alternate periods of immobilization within the splint and active motion exercises. Continued passive motion is not useful.7 Results after open reduction and internal fixation in type II fractures are satisfactory in 90% of the cases. Loss of 10°-15° of ROM usually is seen despite treatment.1,21,23,40
| || |
| || |
Figure 3: AP (A) and lateral (B) radiographs of a radial head fracture extended to the radial neck. Postoperative radiographs of the same patient after the fixation of the fracture using mini-screws and plate (C, D).
Type III Comminuted Fractures
Comminuted fractures are high-energy injuries and are currently treated by early complete excision of the radial head or radial head replacement.1,11,21,23 Partial excision is not recommended.5 Excision should be performed within 48 hours after the injury4 when osteosynthesis is not possible, although these fractures are not considered ideal for internal fixation. Internal fixation techniques are demanding and time consuming in the presence of multiple fragments. These fractures are very difficult to fix due to poor bone quality or inadequate fixation of very small fragments. An intraoperative decision should always be made for an adequate anatomic reduction and stable internal fixation (Figure 4).31,32 If this is not possible the surgeon should be prepared to excise the entire radial head rather than leaving behind inadequate stabilized fragments, which consequently may lead to prolonged immobilization or late displacement.
Figure 4: Various types of the most commonly used radial head implants.
Authors following radial head excision have reported good objective and subjective results.41,42 Delayed excision can be performed,30 but this usually is indicated in patients with no mechanical blocks to the elbow or when other conditions (eg, polytrauma patients) do not allow immediate excision.11 After a short course of immobilization, early active and passive motion of the elbow joint is allowed. This treatment usually gives an optimal result depending on the severity of the initial injury and the presence of associated injuries. Although radial head excision is an easily performed technique, it is often associated with a number of complications (Table 2).
Type IV Fracture-Dislocation
According to Morrey1 radial head fractures with a posterior dislocation of the elbow are classified as complicated injuries. These injuries should be treated by immediate reduction of the dislocation and treatment of the fractured radial head according to the previous mentioned guidelines. Every effort should be made for the preservation of the radial head.
An elbow dislocation is often associated with medial ligaments injuries, which are the primary stabilizers to valgus stress at the elbow. For such cases the preservation of the radial head is of paramount importance in maintaining elbow stability.5 If the radial head cannot be preserved, torn ligaments must be repaired and radial head prosthesis is considered. However, Harrington and Tountas43 have reported radial head replacement without ligamentous reconstruction with satisfactory results. Unfortunately, poor results are associated with this type of fracture. Loss of elbow flexion and forearm rotation of an average 20° usually is seen. A higher incidence of heterotopic ossification is also seen.8 Early motion in <1 week with a hinged splint is favored, with 75% satisfactory results.44 Other complications include injuries to the brachial artery, the median and ulnar nerves, and rarely to the radial nerve.
Radial Head Replacement
Currently, radial head arthroplasty is used in comminuted radial head fractures in an attempt to minimize the complications of radial head excision (Table 2). Its use may be indicated in comminuted fractures of the radial head occurring in combination with tears of the interosseous ligament of the forearm or complex instability after elbow joint dislocation.1,5,11,23
The radial head prosthesis is intended to prevent proximal migration of the radius in response to axial loading of the forearm.45 It resists valgus and posterior elbow instability by providing effective radiocapitellar contact that approaches that of the native radial head. It facilitates the uneventful healing of the medial collateral and interosseous ligaments, as well as the distal radioulnar joint.
The use of the first prosthetic radial head replacement is attributed to Speed,46 who in 1941 implanted ferrule caps over the neck of the radius. Several authors have since developed prosthetic radial heads using a variety of materials such as acrylic,47 vitallium,48,49 and silicone rubber.50 Silicone implants have an overall increase in failure rate compared with metallic implants, including reactive synovitis, inflammatory arthritis, fractures of silastic implants, and a questionable amount of supporting axial stability.31,48,51,52
Knight et al,48 in 1993, showed both clinically and biomechanically that vitallium prostheses could provide excellent resistance to axial load as well as lateral stability in Mason type III and IV comminuted fractures of the radial head. Judet et al53 reviewed the results in five patients who had had an acute radial head fractureMason type IIIwith ligamentous instability. They initially used bipolar titanium prosthesis and later used cobalt-chromium prosthesis with a cemented stem and a polyethylene articulation with the head component. Three results were excellent and two were rated as good. There were no complications in these patients.
Moro et al54 reported their results in 24 patients with unreconstructable fractures of the radial head. Patients were treated with a metallic radial head implant. They concluded that arthroplasty with a metallic radial head implant is a viable treatment option that appears to be safe and effective. Alternatively, implantation of a frozen allograft radial head prosthesis has been used by Szabo et al55 in proximal translation of the radius following radial head excision. They concluded that patients had relief of wrist and elbow pain and reported satisfactory results. The indications and contraindications for a radial head replacement are shown in Table 3. Complications are shown in Table 4.
Radial Head Prosthesis Design
Since Speeds first report on vitallium radial head prosthesis a number of prostheses have been developed with a variety of results reported.46-50 Design configurations based on cadaveric and radiographic measurements were tested with structural finite element method computer analyses. Materials examined included titanium alloy, cobalt-chrome alloy, alumina ceramic, and ultrahigh molecular weight polyethylene (UHMWPE). Metals and ceramic transmitted force at the distal bone and implant interface and strain shielded the proximal radial cortex while UHMWPE distributed load uniformly through the cortex and along the entire bone and implant interface.56-59
Prosthesis design has lagged in adequately matching morphologic characteristics of the proximal radius.60 Most radial head designs are round at their articulation with the capitellum. However, examination of cadaveric specimens demonstrated that the proximal radial head is ovoid in shape. Using CT scans of 8 cadaveric specimens, Cone et al61 demonstrated that maximal diameter exceeds the minimum diameter by an average of 2.5 mm. An additional mismatch of prosthetic radial head components and proximal radius morphology has been demonstrated. Using MRI scans of 46 normal elbows, Beredjiklian et al60 demonstrated that commercially available metallic radial head design may overestimate the dimensions of the radial neck. As a result, ineffective restoration of proximal radial length results (average: 4 mm, range: 1-7 mm) with potentially adverse effects on elbow, forearm, and wrist mechanics. They propose that newer designs taking anatomic dimensions into account may lead to improved function after reconstruction. Recently, in an effort to detect better implant designs, various authors have reported good results with a floating radial-head prosthesis for acute fractures of the radial head.53,62
Various implants for radial head replacement have been developed using either a cemented or a cementless stem. A floating radial head prosthesis (Tornier SA, Saint-Ismier, France) has been designed to articulate both with the humeral condyle and with the radial notch of the ulna.53,62 The radial head of high-density polyethylene enclosed in a cobalt-chrome cup articulates in a semi-constrained manner with the spherical end of a cemented intramedullary stem with a neck-shaft angle of 15°. This semi-constrained implant allows free rotation and a uniplanar arc of motion of 35° from any given point (Figure 4).53,62
Based on the shape-dimensional identification of the radius, a new radial head prosthesis (KPS) was designed. It is a modular prosthesis consisting of two parts: a vitallium stem and a head made of UHMWPE. A ball-and-socket joint between the stem and head allows the head to rotate and tilt. The upper surface of the head is concave to articulate with the spherical capitellum. The lateral surface of the head, which articulates with the concave radial notch of the ulna, is approximated as a barrel-shaped surface. The mobile head of the implant allows for proper positioning and matching of the articulating surfaces during the course of movement or load bearing. The shape of the prosthetic stem is close to being conoidal. Because the stem is cemented in place, there is no need to match the shape of the marrow cavity accurately.57,59
Implants with different design philosophy are currently available. These radial head implants use different stem designs (Avanta Orthopaedics, San Diego, Calif and Pyrocarbon radial head; Ascension Orthopaedics, Austin, Tex with modular tapered stem; Swanson titanium radial head, Wright Medical Technology, Arlington, Tenn with non-modular tapered stem; Evolve modular radial head, Wright Medical Technology with modular non-tapered stem) and are placed without the use of bone cement in the intramedullary canal (Figure 4). The Liverpool radial head replacement (Biomet, Warsaw, Ind) provides an alternative option with the articulating surface of the prosthesis angled at 10° to approximate the position of the natural radial head articulating surface and the stem offset from the body of the prosthesis to approximate the angular curve of the radius (Figure 4).
The evolution of radial head replacement is ongoing. The ideal radial head prosthetic implant has yet to be designed. These data suggest that further study and refinement of prosthesis design is warranted.
Options and Current Thinking
Posterolateral oblique or Kocher approach to the elbow has been standardized as the most suitable for almost all indications concerning operative treatment of radial head pathology. It is a safe and simple procedure with respect to the deep radial nerve and can easily be expanded distally or proximally. In complex elbow instability where a radial head fracture is associated with a torn MCL, a posterior midline incision may be used just distal to the tip of the olecranon (global approach). A full thickness lateral flap (fasciocutaneous) is elevated on the deep fascia to protect the cutaneous nerves. This incision permits access to the medial side of the elbow when the MCL must be repaired to restore elbow stability.15
Traditionally, the operative treatment of radial head fractures is performed through a posterolateral approach with the elbow joint flexed in a pronated position.1,4,5 This recommendation is predicated on an anatomical study by Strachan and Ellis63 that described the position of the posterior interosseous nerve in the cadaver forearm. They showed that pronation moved the posterior interosseous nerve more medially, by <1 cm, from the elbow joint to the radial tubercle. They therefore recommended placing the forearm in pronation during exposure of the radial head to help minimize the chance of posterior interosseous nerve injury.
Diliberti et al64 and Witt et al65 have defined a safe zone that helps the surgeon avoid injuring the posterior interosseous nerve during posterolateral approaches to the proximal part of the radius. Supination was found to decrease this zone while flexion and extension of the elbow joint had no effect on the reported distances of the so-called safe zone. This safe zone in supination was reported to have an average of 52±7.8 mm of the lateral aspect of the radius.65 In a radial head replacement, a typical Kocher exposure allows suboptimal exposure for radial neck cut and offers difficult access for broaching and implant positioning. A more extensile approach like that of Cohen and Hastings,66 which offers improved access, ligament sparing, and perhaps less chance of posterior interosseous nerve injury should be considered.
More recently, we have used the Boyd approach15 to gain access to the radial head (Figure 5). This is the only approach that allows visualization of the radioulnar, radiohumeral, and ulnohumeral joint spaces. A posterior incision is made and the anconeus muscle is peeled off the ulna and elevated anteriorly. The ulnar part of the lateral collateral ligament and the annular ligament are then elevated off the ulna (crista supinatoris) using either a sharp blade or a needle tip electrocautery. The ligament complex is then tagged with a suture for later repair. This exposure allows for excellent visualization of the radial neck and is very helpful in the management of radial neck fractures and for radial head implantation. After the radial head and neck fracture has been addressed, the ligament complex is repaired back to the ulna (crista supinatoris).
Figure 5: Boyd approach for radial head replacement (see text for details).
The Role of Radial Neck Osteotomy
Some of the currently available radial head implants may significantly alter elbow joint kinematics because of a mismatch between their design characteristics and the morphologic characteristics of the proximal radius. In the dynamic setting of elbow function, an ovoid shaped radial head prosthesis will improve function in the proximal radioulnar joint as well as the radiocapitellar joint. The stem of the various prostheses usually does not fit in the proximal radius and that leads to significant alteration of the length of the radius. If an implant has these design characteristics (round radial head shape, radial neck mismatch) then the axis of the radius during supination-pronation movements is severely altered and normal joint kinematics are not replicated.67
Moreover, a review of the literature shows a paucity of information on the proper position of the forearm for the radial neck osteotomy in prosthetic replacement. The axis of forearm rotation represents the most important variable in normal forearm biomechanics and kinematics. The restoration of this axis is of paramount importance when a radial head implant is used. It is well known that if the prosthesis is not oriented properly to the axis of forearm rotation, a cam effect will occur at the radiocapitellar articulation with forearm rotation. This cam effect can lead to postoperative pain and decreased ROM, as well as subluxation and dislocation of the prosthetic radial head implant.
A study was undertaken68 to determine the radiographic anatomy of the proximal radius in three different views (full supination, full pronation, and neutral rotation) and to identify that position that has the smallest value for the angle between the axis of forearm rotation and the radial neck axis. It was our hypothesis that such a position should offer the optimal situation for the radial neck cut in radial head replacement, as it will approximate the normal biomechanical axis of forearm rotation. Anteroposterior and lateral radiographs of 20 healthy volunteers forearms were taken in three views (full supination, neutral rotation, and full pronation). Radial head maximum diameter and angular measurements between the axis of forearm rotation and the radial neck axis were made with digital calipers. Repeated-measures analysis of variance revealed a statistically significant difference between the three AP groups, with supination having the smallest values (P<.0001), but not for the lateral groups (P<.128). Comparison of the axis of forearm rotation-radial neck axis angle between the AP supinated position and the three lateral views revealed a statistically significant difference among all of the pairs, with the AP supinated position having the smallest values. The radial neck axis most closely approximated the axis of forearm rotation with the forearm in the supinated position. For best approximating the native axis of forearm rotation during radial head replacement, the cut should be made perpendicular to the neck axis with the elbow extended and the forearm in the supinated position.
Currently, Mason type I and undisplaced Mason type II fractures can be managed conservatively. Displaced type II fractures can be treated by open reduction and internal fixation to achieve immediate and active mobilization of the neighboring joints. Management of unreconstructible Mason type III and Mason-Johnston type IV comminuted fractures of the radial head is difficult and controversial. Surgical options include internal fixation, excision, or excision and replacement of the radial head. Usually, comminuted fractures of the radial head are treated by excision. When the fracture is associated with ligamentous damage, simple excision may result in gross elbow instability and a poor outcome. Complications, such as valgus elbow deformity, elbow stiffness, proximal radial migration, synostosis, chronic ulnar wrist pain, and degenerative changes, can develop months or years after initially successful treatment. These results have led to a search for a satisfactory prosthesis for a radial head. The ideal prosthetic radial head replacement has yet to be designed.
- Morrey BF. Radial head fracture. In: Morrey BF, ed. The Elbow and its Disorders. 3rd ed. Philadelphia, Pa: WB Saunders; 2000:341-364.
- Mason ML. Some observations on fractures of the head of the radius with a review of one hundred cases. Br J Surg. 1954; 42:123-132.
- Pan WT, Born CT, DeLong WG Jr. Fractures and dislocations involving the elbow joint. In: Dee R, ed. Principles of Orthopaedic Practice. 2nd ed. New York, NY: McGraw-Hill; 1997:411-421.
- Morrey BF. Current concepts in the treatment of fractures of the radial head, the olecranon, and the coronoid. Instr Course Lect. 1995; 77:316-327.
- Sharpe F, Kuschner SH. Radial head fractures. In: Baker CL Jr, Plancher KD, eds. Operative Treatment of Elbow Injuries. New York, NY: Springer-Verlag Inc; 2001:207-223.
- Amis AA, Miller JH. The mechanisms of elbow fractures: an investigation using impact tests in vitro. Injury. 1995; 26:163-168.
- Schatzker J. Fractures of the radial head. In: Schatzker J, Tile M, eds. The Rationale of Operative Fracture Care. 2nd ed. Germany: Springer-Verlag; 1996:131-135.
- Davidson PA, Moseley JB Jr, Tullos HS. Radial head fracture. A potentially complex injury. Clin Orthop Relat Res. 1993; 297:224-230.
- Johnston GW. A follow-up of one hundred cases of fracture of the head of the radius with a review of the literature. Ulster Med J. 1962; 31:51-56.
- Morgan SJ, Groshen SL, Itamura JM, Shankwiler J, Brien WW, Kuschner SH. Reliability evaluation of classifying radial head fractures by the system of Mason. Bull Hosp Jt Dis. 1997; 56:95-98.
- Hotchkiss RN. Fractures and dislocations of the elbow. In: Rockwood CA Jr, Green DP, eds. Fractures in Adults. 4th ed. Philadelphia, Pa: Lippincott-Raven; 1996:929-1024.
- Muller ME, Nazarian S, Koch P, Schatzker J. The comprehensive classification of fractures of long bones. New York, NY: Springer-Verlag; 1990.
- Roidis N, Itamura J, Vaishnav S, Mirzayan R, Learch T, Shean C. MRI evaluation of comminuted radial head fractures. A rather complex injury. Presented at: the 69th Annual Meeting of the American Academy of Orthopaedic Surgeons; February 13-17, 2002; Dallas, Tex.
- Itamura J, Roidis N, Mirzayan R, Vaishnav S, Learch T, Shean C. Radial head fractures. MRI evaluation of associated injuries. J Shoulder Elbow Surg. 2005; 14:421-424.
- Roidis NT, Papadakis SA, Karachalios TS, Mirzayan R, Itamura JM. Radial head fractures. In: Mirzayan R, Itamura JM, eds. Shoulder and Elbow Trauma. New York, NY: Thieme Medical Publishers Inc; 2004:22-35.
- Roidis NT, Karachalios TS, Rigopoulos N, Poultsides L, Malizos KN, Itamura JM. Letter to the Editor. e-JBJS. June 10, 2004.
- Choi J, Learch T, Itamura J, Vaishnav S, Colletti P, Moon C, Terk MR. MR imaging of collateral ligaments in the flexed elbow. AJR Am J Roentgenol. 2001; 176(suppl):140.
- Herbertsson P, Josefsson PO, Hasserius R, Karlsson C, Besjakov J, Karlsson M. Long-Term Follow-Up Study. Uncomplicated Mason type-II and III fractures of the radial head and neck in adults. A long-term follow-up study. J Bone Joint Surg Am. 2004; 86:569-574.
- Ring D. More information on radial head fractures. Letter to the Editor. e-JBJS. May 4, 2004.
- Hausman MR, Mullett H. Outcome of Mason type II & III radial head fractures. Letter to the Editor. e-JBJS. April 14, 2004.
- Quintero J. Olecranon/radial head/complex elbow injuries. In: Ruedi M, Murphy WM, eds. AO Principles of Fracture Management. New York, NY: Thieme Medical Publishers Inc; 2000:323-338.
- Greenspan A, Norman A. Radial head-capitellum view: an expanded imaging approach to elbow injury. Radiology. 1987; 164:272-274.
- McKee MD, Jupiter JB. Trauma to the adult elbow and fractures of the distal humerus. In: Browner BD, Jupiter JB, Levine AM, Trafton PG, eds. Skeletal Trauma. 2nd ed. Philadelphia, Pa: WB Saunders; 1998:1455-1522.
- Holdsworth BJ, Clement DA, Rothwell PN. Fractures of the radial headthe benefit of aspiration: a prospective controlled trial. Injury. 1987; 18:44-47.
- Thompson JD. Comparison of flexion versus extension splinting in the treatment of Mason type I radial head and neck fractures. J Orthop Trauma. 1988; 2:117-119.
- Unsworth-White J, Koka R, Churchill M, et al. The nonoperative management of radial head fractures: a randomized trial of three treatments. Injury. 1994; 25:165-167.
- Kuntz DG, Jr, Baratz ME. Fractures of the elbow. Orthop Clin North Am. 1999; 30:37-61.
- Hotchkiss R. Displaced fractures of the radial head: Internal fixation or excision? J Am Acad Orthop Surg. 1997; 5:1-10.
- MacAusland WR Jr, Wyman ET Jr. Fractures of the adult elbow. Instr Course Lect. 1975; 24:169.
- Broberg MA, Morrey BF. Results of delayed excision of the radial head after fracture. J Bone joint Surg Am. 1986; 68:669-674.
- Furry KL, Clinkscales CM. Comminuted fractures of the radial head. Arthroplasty versus internal fixation. Clin Orthop Relat Res. 1998; 353:40-52.
- Ring D, Quintero J, Jupiter JB. Open reduction and internal fixation of fractures of the radial head. J Bone Joint Surg Am. 2002; 84:1811-1815.
- McArthur RA. Herbert screw fixation of fracture of the head of the radius. Clin Orthop Relat Res. 1987; 224:79-87.
- Caputo AE, Mazzocca AD, Santoro VM. The nonarticulating portion of the radial head: anatomic and clinical correlations for internal fixation. J Hand Surg Am. 1998; 23:1082-1090.
- Pelto K, Hirvensalo E, Bostman O, Rokkanen P. Treatment of radial head fractures with absorbable polyglycolide pins: a study on the security of the fixation in 38 cases. J Orthop Trauma. 1994; 8:94-98.
- Hotchkiss RN. Fractures of the radial head and related instability and contracture of the forearm. Instr Course Lect. 1998; 47:173-177.
- Keller HW, Rehm KE, Helling J. Intramedullary reduction and stabilisation of adult radial neck fractures. J Bone Joint Surg Br. 1994; 76:406-408.
- Patterson JD, Jones CK, Glisson RR, Caputo AE, Goetz TJ, Goldner RD. Stiffness of simulated radial neck fractures fixed with 4 different devices. J Shoulder Elbow Surg. 2001; 10:57-61.
- Soyer AD, Nowotarski PJ, Kelso TB, Mighell MA. Optimal position for plate fixation of complex fractures of the proximal radius: a cadaver study. J Orthop Trauma. 1998; 12:291-293.
- Esser RD, Davis S, Taavao T. Fractures of the radial head treated by internal fixation: late results in 26 cases. J Orthop Trauma. 1995; 9:318-323.
- Coleman DA, Blaire WF, Shurr D. Resection of the radial head for fracture of the radial head. J Bone Joint Surg Am. 1987; 69:385-392.
- Morrey BF, Chao EY, Hui FC. Biomechanical study of the elbow following excision of the radial head. J Bone Joint Surg Am. 1979; 61:63-68.
- Harrington IJ, Tountas AA. Replacement of the radial head in the treatment of unstable elbow fractures. Injury. 1981; 12:405-412.
- Broberg MA, Morrey BF. Results of treatment of fracture-dislocations of the elbow. Clin Orthop Relat Res. 1987; 216:109-119.
- Hotchkiss RN, An KA, Sowa DT, Basta S, Weiland AJ. An anatomic and mechanical study of the interosseous membrane of the forearm: pathomechanics of proximal migration of the radius. J Hand Surg Am. 1989; 14(2 Pt 1):256-261.
- Speed K. Fracture of the head of the radius. Surg Gynecol Obset. 1941; 73:845-850.
- Cherry JC. Use of acrylic prosthesis in the treatment of fracture of the head of the radius. J Bone Joint Surg Br. 1953; 35:70-71.
- Knight DJ, Rymaszewski LA, Amis AA, Miller JH. Primary replacement of the fractured radial head with a metal prosthesis. J Bone Joint Surg Br. 1993; 75:572-576.
- Carr CR. Metallic cap replacement of the radial head. J Bone Joint Surg Am. 1971; 53:1661.
- Swanson AB, Jaeger SH, La Rochelle D. Comminuted fractures of the radial head. The role of silicone-implant replacement arthroplasty. J Bone Joint Surg Am. 1981; 63:1039-1049.
- Morrey BF, Askew L, Chao EY. Silastic prosthetic replacement for the radial head. J Bone Joint Surg Am. 1981; 63:454-458.
- Carn RM, Medige J, Curtain D, Koenig A. Silicone rubber replacement of the severely fractured radial head. Clin Orthop Relat Res. 1986; 209:259-269.
- Judet T, Garreau De Loubresse C, Piriou P, Charnley G. A floating prosthesis for radial-head fractures. J Bone Joint Surg Br. 1996; 78:244-249.
- Moro JK, Werier J, MacDermid JC, Patterson SD, King GJW. Arthroplasty with a metal radial head for unreconstructible fractures of the radial head. J Bone Joint Surg Am. 2001; 83:1201-1211.
- Szabo RM, Hotchkiss RN, Slater RR Jr. The use of frozen-allograft radial head replacement for treatment of established symptomatic proximal translation of the radius: preliminary experience in five cases. J Hand Surg Am. 1997; 22:269-278.
- Gupta GG, Lucas G, Hahn DL. Biomechanical and computer analysis of radial head prostheses. J Shoulder Elbow Surg. 1997; 6:37-48.
- Pomianowski S, Morrey BF, Neale PG, Park MJ, ODriscoll SW, An KN. Contribution of monoblock and bipolar radial head prostheses to valgus stability of the elbow. J Bone Joint Surg Am. 2001; 83:1829-1834.
- van Riet RP, Van Glabbeek F, Baumfeld JA, et al. The effect of the orientation of the noncircular radial head on elbow kinematics. Clin Biomech (Bristol, Avon). 2004; 19:595-599.
- Skalski K, Swieszkowski W, Pomianowski S, Kedzior K, Kowalik S. Radial head prosthesis with a mobile head. J Shoulder Elbow Surg. 2004; 13:78-85.
- Beredjiklian PK, Nalbantoglu U, Potter HG, Hotchkiss RN. Prosthetic radial head components and proximal radial morphology: a mismatch. J Shoulder Elbow Surg. 1999; 8:471-475.
- Cone RO, Szabo R, Resnick D, Gelberman R, Taleisnik J, Gilula LA. Computed tomography of the normal radioulnar joints. Invest Radiol. 1983; 18:541-545.
- Popovic N, Gillet P, Rodriguez A, Lemaire R. Fracture of the radial head with associated elbow dislocation: results of treatment using a floating radial head prosthesis. J Orthop Trauma. 2000; 14:171-177.
- Strachan JCH, Ellis BW. Vulnerability of the posterior interosseous nerve during radial head resection. J Bone Joint Surg Br. 1971; 53:320-323.
- Diliberti T, Botte MJ, Abrams RA. Anatomical considerations regarding the posterior interosseous nerve during posterolateral approaches to the proximal part of the radius. J Bone Joint Surg Am. 2000; 82:809-813.
- Witt J. Toward safe exposure of the proximal part of the radius: landmarks and measurements. J Bone Joint Surg Am. 2001; 83:1589-1590.
- Cohen MS, Hastings H II. Post-traumatic contracture of the elbow. Operative release using a lateral collateral ligament sparing approach. J Bone Joint Surg Br. 1998; 80:805-812.
- Birkedal JP, Deal DN, Ruch DS. Loss of flexion after radial head replacement. J Shoulder Elbow Surg. 2004; 13:208-213
- Roidis N, Stevanovic M, Martirosian A, Abbott DD, McPherson EJ, Itamura JM. A radiographic study of proximal radius anatomy with implications in radial head replacement. J Shoulder Elbow Surg. 2003; 12:380-384.
Drs Roidis, Rigopoulos, Basdekis, Poultsides, Karachalios, and Malizos are from the Department of Orthopedics, University of Thessaly, Larissa, and Dr Papadakis is from the Department of Orthopedics, Health Center of Mykonos, Mykonos, Greece, and Dr Itamura is from the Department of Orthopedics, Keck School of Medicine, Los Angeles, Calif.
Drs Roidis, Papadakis, Rigopoulos, Basdekis, Poultsides, Karachalios, Malizos, and Itamura have no industry relationship to declare.
Reprint requests: Nikolaos T. Roidis, MD, PhD, DSc, Dept of Orthopedics, University of Thessaly, 34 Akronos St, Larissa 41447, Hellenic Republic, Greece.