桡骨头置换 资料 In-depth 知情同意

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

• Radial head replacement is a reasonable option for patients with comminuted radial head fractures and complex elbow trauma [2].
• Primary radial head replacement is preferred over failed internal fixation because the latter typically does not result in a pain-free elbow due to damaged cartilage surfaces [8].
• Better outcomes are reported for radial head arthroplasty compared to radial head excision in terms of elbow stability, range of motion, pain, and fewer complications [9].
• Radial head replacement is recommended for comminuted fractures with satisfactory medium- and long-term results [14].
• Adequate knowledge of surgical indications, types of implants, and surgical technique are essential for a satisfactory outcome when a radial head prosthesis is used for the treatment of nonreconstructable radial head fractures [6].
• The reproducibility of results would be improved by using a minimum follow-up of three years combined with a consensus of the definition of the reasons for failure after radial head arthroplasty [3].
• The current data provide no evidence for a specific radial head prosthesis design due to the variety of implant designs and limited evidence [4].
• Implant fixation type does not appear to affect functional outcomes of radial head arthroplasty [5].
• Midterm outcomes of EVOLVE radial head prosthesis are satisfactory, and associated complication rates are low [7].
• Bipolar-cemented implants show lower revision rates [14].
• Overlengthening is a complication of radial head replacement [1].
• The preferred treatment for failed radial head arthroplasty depends mainly on the chondral condition and stability of the elbow joint [13].

Anatomy & Pathophysiology

Bony Anatomy

• The radial head consists of a concave dish that articulates with the capitellum and a flattened articular margin that articulates with the lesser sigmoid (radial) notch of the ulna [37].
• The nonarticular margin of the radial head comprises about one-third of the diameter and is often devoid of cartilage [37].
• The radial head is elliptical in shape rather than circular, and the radiocapitellar dish is typically offset from the neck of the radius [37].
• The radial head has a slightly elliptical cross section and interdigitates with the lesser sigmoid notch, the lateral lip of the trochlea, and the capitellar articular surface [50].
• The proximal radius has a slight angulation with respect to the shaft that complicates reconstruction or replacement [50].
• The radial head is seated in the lesser sigmoid notch and has axial contact with the capitellum of the distal humerus [27].
• The radial head is disk-shaped and of greater diameter than the neck, which rotates within the annular ligament [44].
• The radial head has a shallow cuplike surface that articulates with the capitellum proximally and the radial notch of the ulna medially [44].
• The biceps inserts on the tuberosity of the radial head immediately distal to the neck [44].

Vascular Supply

• The vascular supply of the radial head is provided by branches of the radial recurrent artery and a branch of the ulnar artery that form a pericervical arterial ring [37].
• A branch of the interosseous artery supports the neck of the radius, and the nutrient artery provides intraosseous blood supply [37].
• The vascular supply to the radial head is limited and tenuous [50].
• In children, the blood supply to the epiphysis is supplied through the more distal metaphysis because the entire radial head is covered with articular cartilage [44].

Ligaments and Stability

• The radial head plays an important role as a secondary valgus stabilizer of the elbow [19].
• The radial head is the secondary restraint to valgus stability of the elbow [27].
• The ligaments have the most marked influence on elbow stability, particularly when the upper limb is positioned such that valgus and varus gravity loads are applied [22].
• The radial head is an important secondary stabilizer of the elbow, and excision alone is contraindicated in the presence of extensive damage to primary stabilizers such as the medial collateral ligament, coronoid, interosseous membrane, or lateral collateral ligament [19].
• Excision of the radial head in the presence of concomitant ligamentous or bony injury leads to loss of radiocapitellar contact forces and precipitates instability [15].
• Even in the presence of intact collateral ligaments, radial head excision alone has been shown to alter elbow kinematics [15].
• The addition of a coronoid fracture to an elbow dislocation with a radial head fracture substantially increases the chances of acute and chronic instability and posttraumatic elbow arthrosis [47].

Mechanism of Injury

• Radial head fractures typically result from a fall on an outstretched hand with the forearm in pronation, resulting in an axial load on the elbow [19].
• Radial head fractures are generally caused by longitudinal loading from a fall on an outstretched hand, and dislocation of the elbow is another cause [27].
• Fractures of the radial head or neck usually result from a fall onto an outstretched hand with the elbow in extension and valgus [44].
• This valgus extension force may also produce other injuries, including avulsion of the medial epicondyle, rupture of the medial collateral ligament, and fracture of the olecranon, proximal ulna, or lateral condyle [44].
• Fracture of the radial neck may occur as a result of dislocation of the elbow, where the radial neck is fractured by impact against the inferior aspect of the capitellum at the time of posterior dislocation or spontaneous reduction [44].
• A radial head fracture may also occur with anterior dislocation of the elbow and produce anterior displacement of the head [44].

Associated Injuries

• Approximately 20% of all elbow fractures involve the radial head [19].
• Radial head fractures account for 15–25% of all elbow fractures [27].
• Radial head fractures often are associated with more complex injuries, such as associated elbow fractures, dislocations, and soft-tissue injuries [19].
• Of patients with radial head fractures, 30% have other soft-tissue and skeletal injuries, including carpal fractures, distal radioulnar joint disruption, interosseous membrane disruption, coronoid fractures, Monteggia fracture-dislocations, capitellar fractures, and medial and lateral collateral ligament injuries [19].
• Associated injuries are common in radial head fractures [27].
• In children, approximately 50% of radial neck fractures are associated with other injuries to the elbow [44].

Pathophysiology of Instability and Arthrosis

• Displaced unstable radial head fractures require restoration of radiocapitellar contact via reconstruction or prosthetic replacement to prevent elbow instability [11].
• Restoration of radiocapitellar contact is theorized to reduce problems associated with radial head fractures [12].
• Long-term outcome studies of radial head excision have shown a high incidence of radiographic arthritis, an increase in the carrying angle, and proximal radial migration [38].
• Broberg and Morrey noticed a 92% incidence of arthrosis 10 years after fracture-dislocation treatment without repair or replacement of the radial head [27].
• Anatomic radial head replacement has a risk of radiographic technical mistakes that correlate to poorer outcomes [10].
• Overlengthening (overstuffing) with the placement of a radial head prosthesis that is too thick may be associated with the development of pain, stiffness, and capitellar wear [33].
• Radial head implant maltracking causes premature capitellar cartilage wear, pain, limited rotation, and may contribute to loosening of fixed stem prostheses [33].
• An implant whose diameter is too large may cause an erosion of the lateral trochlea, prevent optimal closure of the annular ligament, and may contribute to residual instability [33].

Classification

• The Mason classification, introduced in 1954, remains the most referenced classification system for radial head fractures [26].
• Mason type I fractures are defined as non-displaced fissures or peripheral rim fractures [26, 61].
• Mason type II fractures are characterized by marginal sector fractures with displacement [26, 61].
• Mason type III fractures encompass comminuted, displaced fractures involving the entirety of the radial head [26, 61].
• Johnston added a fourth type to the Mason classification in 1962 to signify radial head fractures accompanied by dislocation, irrespective of displacement or fragment comminution [26, 61].
• Broberg and Morrey modified the Mason classification in 1987 by suggesting that a partial radial head fracture must be of sufficient size (at least 30% of the articular surface) and displacement (at least 2 mm) to be considered a displaced fracture (Mason type II) [26].
• The Mason and modified Mason classifications exhibit limitations, including moderate inter- and intraobserver reliability and inconsistent guidance regarding treatment or prognostic prediction [26].
• Hotchkiss modified the Mason classification in 1997 to include indications for surgical intervention [26].
• In the Hotchkiss modification, type II fractures are defined as displaced fractures of the radial head or neck combined with mechanical blocking of joint motion or with loss of joint congruity [61].
• In the Hotchkiss modification, type III fractures are characterized by comminution that precludes internal fixation and requires either resection or prosthetic replacement of the radial head [61].
• A limitation of the Mason and Hotchkiss classifications is their poor intra-observer and inter-observer reproducibility [61].
• The Mason and Hotchkiss classifications fail to consider concomitant lesions, which are present in nearly 80% of multi-fragment fractures, particularly Type III fractures [61].
• The Mayo Clinic classification considers all concomitant lesions and is preferred over the Mason classification for this reason [61].
• In the Mayo Clinic classification, the radial head fracture is described using the Mason classification, with letters added to indicate concomitant lesions [61].
• In the Mayo Clinic classification, upper case letters indicate treated concomitant lesions and lower case letters indicate untreated concomitant lesions [61].
• Recommendations for surgical treatment of radial head and neck fractures according to the Mason classification can be given with the best available evidence [16].

Clinical Presentation

Epidemiology and Mechanism

• Radial head fractures can occur in isolation but are often associated with more complex injuries, including elbow fractures, dislocations, and soft-tissue injuries [19].
• 30% of patients with radial head fractures have other soft-tissue and skeletal injuries, including carpal fractures, distal radioulnar joint (DRUJ) and interosseous membrane disruption, coronoid fractures, Monteggia fracture-dislocations, capitellar fractures, and medial and lateral collateral ligament injuries [19].
• Patients with a high-energy injury mechanism merit careful evaluation for more complex injury patterns that could potentially be missed [15].

Physical Examination

• The patient should be questioned carefully about concomitant wrist, forearm, or shoulder pain [19].
• Physical examination includes pain with palpation over the radial head [19].
• The surgeon should examine elbow range of motion (ROM) and assess for a block to pronation/supination or flexion/extension [19].
• The surgeon should examine the forearm, wrist, and elbow for tenderness along the course of the interosseous membrane (Essex-Lopresti lesion), instability of the DRUJ, pain at the medial side of the elbow (medial collateral ligament [MCL]), and pain at the lateral side of the elbow (lateral collateral ligament [LCL]) [19].
• Lateral elbow pain and tenderness or limitation in elbow or forearm motion should alert the examiner to the possibility of a radial head fracture [19].
• Joint aspiration of the intra-articular hematoma and injection of a local anesthetic can be helpful when assessing mechanical blocks to motion [19].

Imaging

• AP and lateral radiographs of the elbow are routinely obtained [19].
• Nondisplaced fractures of the radial head may not be visible on radiographs but may be diagnosed by elevation of the anterior and posterior fat pads (the sail sign) by an intra-articular hemarthrosis [19].
• The radiocapitellar view is accomplished by positioning the patient as for a lateral view but angling the tube 45° toward the shoulder [19].
• For comminuted fractures, CT can delineate the location, number, and size of the fragments and is rapidly emerging as a standard imaging method for more complicated radial head fractures [19].

Classification

• The Mason classification of radial head fractures is used to categorize these injuries [19].
• Mason Type I fractures are minimally displaced [19].
• Mason Type II fractures are displaced [19].
• Mason Type III fractures are comminuted and displaced [19].

Indications for Operative Intervention

• Patients with displaced radial head fractures with a block to motion, comminuted fragments, associated elbow instability, or retained intra-articular fragments may benefit from operative intervention [15].
• Displaced unstable fractures require restoration of radiocapitellar contact via reconstruction or prosthetic replacement to prevent elbow instability [11].
• Radial head fractures that are significantly displaced, block motion (especially rotation), or are part of more complicated injury patterns are candidates for surgical repair [19].
• Unstable or unpredictable fixation of complex radial head fractures should probably be treated with prosthetic replacement to avoid instability of the forearm or elbow [24].
• In the setting of an irreconstructable radial head and neck fracture, radial head arthroplasty is an excellent option in restoring radiocapitellar contact and elbow stability [15].
• Radial head replacement is a good treatment option in cases with more than three fracture fragments, which have a higher rate of failure with surgical fixation [19].
• Radial head fracture fixation has a higher failure rate if there is associated elbow instability [19].

Indications for Non-Operative Management

• Most fractures of the radial head are stable and managed non-operatively with good long-term results [11].
• Most minimally displaced (<3 mm) radial head fractures can be treated nonsurgically if no block to ROM is present [19].
• Based on the current evidence, conservative management of isolated Mason II radial head fractures yields favorable therapeutic outcomes with a low incidence of complications [36].

Indications for Fragment Excision

• Fragment excision can be used in patients with a block to forearm motion and a small displaced articular fracture of the radial head (<25% of the articular diameter) [15].
• Complete radial head excision can be considered for isolated displaced multifragmentary radial head fractures that are not amenable to internal fixation [15].
• The radial head should not be excised in the presence of concomitant ligamentous or bony injury, as doing so will lead to loss of radiocapitellar contact forces and precipitate instability [15].
• If excision is to be performed, the push–pull test intraoperatively should have no more than 2 to 4 mm of movement of the radius and a careful fluoroscopic examination should be performed to rule out any signs of instability [15].
• Even in the presence of intact collateral ligaments, excision alone has been shown to alter elbow kinematics and thus is infrequently performed [15].
• Radial head excision alone is contraindicated in clinical settings in which extensive damage to the primary stabilizers (MCL: valgus instability; coronoid: posterior instability; interosseous membrane: longitudinal instability; LCL: posterolateral rotatory instability) is present [19].

Indications for Open Reduction and Internal Fixation (ORIF)

• Clear indications for ORIF include displaced, noncomminuted fractures of the radial head that impede rotation, or those associated with dislocation [15].
• Fractures with greater than 2 mm of displacement and greater than 30% of the articular surface (Mason II fractures) are indications for operative fixation, although this remains controversial [15].
• The best candidates for ORIF are young patients with three or fewer fragments and good articular cartilage [15].
• Attempted fixation when there are more than three fragments can be fraught with fragment nonunion, osteonecrosis, failure of fixation, and unpredictable forearm motion requiring subsequent hardware removal [15].
• In young patients, the risks of ORIF need to be weighed against the long-term effects of radial head arthroplasty [15].

Clinical Outcomes and Complications

• Clinical outcome studies of metallic radial head arthroplasty systems indicate that head replacement is a reasonable option to offer patients with comminuted radial head fractures and complex elbow trauma [2].
• Better outcomes are reported for radial head arthroplasty in terms of elbow stability, range of motion, pain, and fewer complications compared to radial head excision [9].
• The outcome after primary resection of the radial head without replacement is controversial, with some authors reporting good results and others reporting a high incidence of pain, valgus and/or axial instability, elbow dislocation, weakness, degenerative elbow, and/or wrist arthritis [58].
• Morrey et al. reported 80% satisfactory results after resection for displaced fractures of the radial head at an average of 20 years’ follow-up [58].
• Mild ulnohumeral arthritis was common radiographically after resection, but residual symptoms were uncommon and mild [58].
• Wrist pain occurred in 15% of patients after resection but was usually mild [58].
• Proximal migration averaged 2 mm after resection [58].
• Fuchs and Chylarecki assessed the outcome of 108 patients after radial head resection at an average of 6 years, finding that clinical outcome and strength were better for patients treated with a primary versus a secondary radial head resection [58].
• Ikeda and Oka reviewed 15 patients treated with early radial head resection for a fracture of the radial head at an average of 10 years, finding that all patients had reduced elbow power and only 5 of them were pain-free [58].
• Janssen and Vetger reported on a follow-up of 21 patients with a Mason type III fracture treated by excision of the radial head at between 16 and 30 years, finding that only 4 of their patients had elbow pain and 11 of 16 patients with radiographic follow-up had degenerative arthritis of the elbow [58].
• Berger and coworkers reported good or excellent results in 10 of 30 patients at an average of 5 years after resection, noting that valgus deformity of the elbow was common [58].
• Josefsson et al. reported on 23 patients with an elbow dislocation associated with a displaced fracture of the radial head who had the radial head excised at an average of 2 days after injury, finding that redislocation occurred in 4 patients with an associated displaced fracture of the coronoid process [58].
• A follow-up examination performed in 19 patients between 3 and 34 years after injury by Josefsson et al. demonstrated severe osteoarthritis in 12 elbows, with reduced range of motion being the most common complaint and reduced extension the most common finding [58].
• Mikic and Vukadinovic reported on 58 patients treated with excision of a radial head reviewed at an average of 6.5 years, finding osteoarthritis in 52%, residual symptoms in 43%, limited forearm rotation in 58%, and symptomatic proximal migration of the radius with distal radioulnar joint symptoms in 25% [58].
• Antuna and coworkers reviewed 26 patients at an average follow-up of 25 years following a primary radial head excision for a displaced radial head fracture without associated elbow instability, finding that the functional outcome was good or excellent in 92% of the patients, increased carrying angle and osteoarthritis were present in all, and wrist pain was only significant in 3 patients [58].
• Stiffness, especially forearm rotation, is a complication of radial head fractures [19].
• Replacement of the radial head with a prosthesis that is too large (overstuffing the joint) is a complication of radial head fractures [19].
• Fracture displacement occurs in <5% of cases [19].
• Radiocapitellar arthritis is a complication of radial head fractures [19].
• Infection is a complication of radial head fractures [19].
• Loss of fixation is a complication of radial head fractures [19].
• The best estimate for revision rate of radial head arthroplasty is 2 per 100 person years of follow-up [23].
• Failure of primary radial head replacement may be due to infection, peri-prosthetic fracture, implant loosening, dislocation, dis-assembly, heterotopic ossification or persistent pain [23].
• Stress shielding may be observed with press fit designs but has not been shown to lead to implant failure [23].
• Implant loosening may be attributed to the implant design, but in many cases surgical factors predispose to early failure, including over-stuffing, improper alignment, inadequate fixation or persistent instability [23].
• Persistent instability may be due to inadequate soft tissue repair or inadequate management of an associated ulna fracture [23].
• Retrospective reviews have identified hospital factors, implant factors and patient factors that can lead to reoperation, including the use of a silicone implant, younger age, fewer co-morbidities and delay to surgery [23].
• Patients with failed radial head implants can present with persistent pain, stiffness, infection, instability of the radiocapitellar joint, ulnohumeral joint or both [23].
• Loss of range of movement in both the flexion extension and pronosupination axis is reported with failed radial head implants, with average extension lag of 30°, flexion up to 117°, and pronation from 58° to 52° supination on average [23].
• A common feature of those presenting with failed radial head implants is delay to initial surgery [23].
• Overlengthening of the radial column is a complication of radial head replacement [1].
• Due to the variety of implant designs and limited evidence, current data provide no evidence for a specific radial head prosthesis design [4].
• Adequate knowledge of the surgical indications, types of implants, and surgical technique are essential for a satisfactory outcome when a radial head prosthesis is used for the treatment of nonreconstructable radial head fractures [6].
• The ligaments have the most marked influence on stability, particularly when the upper limb is positioned such that valgus and varus gravity loads are applied to the elbow [22].
• Recommendations for surgical treatment of radial head and neck fractures according to the Mason classification can now be given with the best available evidence [16].

Investigations

• AP and lateral radiographs of the elbow are routinely obtained for radial head fractures [19].
• Nondisplaced radial head fractures may not be visible on radiographs but may be diagnosed by elevation of the anterior and posterior fat pads (the sail sign) by an intra-articular hemarthrosis [19].
• CT can delineate the location, number, and size of fragments and is rapidly emerging as a standard imaging method for more complicated radial head fractures [19].
• Aspiration of the intra-articular hematoma and injection of a local anesthetic can be helpful when assessing mechanical blocks to motion [19].
• The surgeon should examine elbow range of motion and assess for a block to pronation/supination or flexion/extension [19].
• The surgeon should examine the forearm, wrist, and elbow for tenderness along the course of the interosseous membrane, instability of the distal radioulnar joint, pain at the medial side of the elbow, and pain at the lateral side of the elbow [19].
• A careful inspection of the preoperative imaging is required to rule out associated fractures if radial head excision is contemplated [18].
• The stability of the elbow and forearm should be evaluated fluoroscopically with varus, valgus, rotational, and axial stress tests before and after radial head excision [18].
• A fluoroscopic examination to rule out concomitant ligament injuries using varus, valgus, rotational, and axial stress tests is performed during open radial head excision [18].
• A fluoroscopic evaluation of the elbow is performed to look for retained fragments and to reevaluate elbow and forearm stability after excision [18].
• If radial head excision is to be performed, the push–pull test intraoperatively should have no more than 2 to 4 mm of movement of the radius and a careful fluoroscopic examination should be performed to rule out any signs of instability [15].
• Fluoroscopic confirmation of removal of fragments is a preventive measure for retained fragments during fragment or radial head resection [25].
• Fluoroscopic examination before and after fragment or radial head excision is a preventive measure for elbow or forearm instability [25].
• The diagnosis of Monteggia fracture can be made with standard anteroposterior and lateral radiographs of the elbow, and it is essential that the elbow be viewed in both planes for all patients with forearm fractures [49].
• A line drawn through the center of the radial neck should extend through the central portion of the capitellum regardless of elbow position [49].
• In rare instances when radiographs are equivocal, advanced imaging, such as CT, MRI, or ultrasound, should be used for Monteggia fractures [49].
• The absence of trauma and changes such as a hypoplastic capitellum and a flattened convex radial head on radiographs should raise suspicion for a congenital radial head dislocation [49].
• Magnetic resonance imaging can be helpful in distinguishing congenital radial head dislocation from a traumatic dislocation [31].
• In congenital radial head dislocation, the radial head generally remains intra-capsular, whereas in a traumatic radial head dislocation, the radial head usually tears through the elbow joint capsule [31].
• The shapes of the cartilaginous radial head and capitellum can be assessed using MRI [31].
• In congenital radial head dislocation, the radial head is generally convex instead of concave, and the capitellum is hypoplastic and ovoid instead of convex [31].
• A line drawn through the longitudinal axis of the radial shaft does not bisect the capitellum in congenital radial head dislocation [31].
• The radial head is dome-shaped in congenital radial head dislocation [31].
• The ulna bows depending on the direction of the radial head dislocation, with anterior dislocations causing a bow into extension and posterior dislocations causing a bow into flexion [31].
• Additional radiographic findings for congenital radial head dislocation include dysplasia of the capitellum and ulnar-positive variance of the wrist [31].

Treatment

Indications and Decision Making

• Head replacement is a reasonable option for patients with comminuted radial head fractures and complex elbow trauma [2].
• A modular metallic radial head arthroplasty system should always be available when operating on displaced radial head fractures because comminution is often more severe than predicted by plain radiographs or CT [51].
• Indications for radial head arthroplasty include displaced unreconstructible fractures larger than one-third of the diameter of the radial head with known or probable medial or lateral collateral ligament or interosseous membrane injury [59].
• Indications for radial head arthroplasty include nonunion, malunion, and posttraumatic arthritis of the radial head [59].
• Radial head replacement is recommended to help stabilize the joint and facilitate early mobilization in radial head fractures associated with elbow dislocations where the lateral ulnar collateral ligament is injured [57].
• A radial head implant may mitigate proximal migration of the radius after simple radial head excision in Essex-Lopresti lesions [57].
• Conservative management of isolated Mason II radial head fractures yields favorable therapeutic outcomes with a low incidence of complications [36].
• Most radial head fractures are stable and managed non-operatively with good long-term results [11].

Implant Selection and Design

• Current data provide no evidence for a specific radial head prosthesis design due to the variety of implant designs and limited evidence [4].
• Bipolar-cemented implants show lower revision rates in radial head replacement [14].
• There is no evidence to support one type of radial head implant design over others, with the exception of silicone prostheses that have been abandoned [57].
• Smooth stemmed implants have demonstrated lower rates of proximal radial osteolysis compared with porous ingrowth designs [57].
• Rigid implant fixation in the proximal radius has been linked to increased complications and revision rates, particularly loosening [57].
• A monopolar implant provides a good clinical outcome with the benefit of being cost effective, given no clinical difference in use of monopolar and bipolar metallic arthroplasty systems [55].
• The use of a silicone implant is identified as a hospital factor that can lead to reoperation [23].

Surgical Technique and Sizing

• The optimal implant diameter is typically the minor diameter of the elliptical native radial head, most commonly 2 mm smaller than the maximum diameter [33].
• When in-between sizes, a smaller prosthesis is chosen both in diameter as well as thickness [33].
• The proximal edge of the prosthesis should sit no more than 1-mm proximal to the corner of the lesser sigmoid notch of the coronoid [55].
• Any distraction or angulation at the lateral ulnohumeral joint indicates overstuffing [55].
• The radial head prosthesis should articulate at the level of radial notch, 2-mm distal to the coronoid [59].
• Choosing the size of prosthesis by evaluating the gap between the radial head and capitellum often results in overlengthening of the radius since the lateral ligaments are often incompetent in patients undergoing radial head arthroplasty [59].
• An oversized radial head implant can increase tension on the interosseous membrane with subsequent risk of stiffness and pain [57].
• More than 2 mm of lengthening can increase radiocapitellar contact pressures [57].
• Gapping in the lateral ulnohumeral joint line is a reliable indicator of radial head overlengthening [57].
• Changes in the medial ulnohumeral joint line were apparent only after 6 mm of overlengthening [57].
• Radiographic parameters are not very useful to detect overlengthening of the radial head [33].
• The lateral ulnohumeral joint is often wider in normal patients [33].
• Overlengthening causes the medial ulnohumeral joint to open laterally, which may not be evident until there is 6- to 8-mm overlengthening of the radial head insert [33].
• If the radial head implant is not tracking optimally with the capitellum during forearm rotation, downsize the stem diameter of a smooth stem implant or reposition the stem of a fixed stem implant to correct this [33].
• The annular ligament must be sectioned to adequately expose the radial head and neck and to facilitate the prosthesis insertion [33].
• Thorough irrigation is recommended to remove all bony debris to minimize risk of heterotopic ossification [55].
• A fresh saw cut at the junction of the head/neck or at the level of the fracture is made to create a stable, straight base [55].
• The canal can be prepared with a canal finder and subsequent rasps as per the manufacturer guidelines [55].
• A Homan retractor placed posterior to the radial neck is used to gently lever the proximal radius laterally to allow access to the radial neck [33].
• If a smooth stem prosthesis is to be used, choose a stem 1 mm smaller than the maximum-sized diameter neck rasp to allow the stem to move slightly in the neck [33].
• This allows the stem to move within the canal to compensate for the difference in shape between the circular implant and the elliptical native radial head as guided by the annular ligament [33].
• A range of motion test should be performed as well as a stability test with manual varus and valgus stress at the elbow in extension after placing trial implants [55].
• Careful repair of the annular ligament and rehabilitation of any concomitant osseous and ligament injuries are required to maintain elbow stability following insertion of the definitive radial head prosthesis [33].
• Appropriate reattachment of the lateral ligamentous complex is necessary to prevent edge binding of the radial head prosthesis [57].

Postoperative Care and Rehabilitation

• Immediate active motion in a soft dressing is permitted if there are no associated injuries [33].
• Concomitant ligament injuries will direct the rehabilitation plan as outlined in the section on operative treatment of elbow dislocations [33].
• Early range-of-motion exercises are critical to avoid soft tissue adherence to radial neck [59].

Complications and Failure

• Implant loosening may be attributed to the implant design, but in many cases surgical factors predispose to early failure [23].
• Surgical factors predisposing to early failure include over-stuffing, improper alignment, inadequate fixation or persistent instability [23].
• Persistent instability can be due to inadequate soft tissue repair or inadequate management of an associated ulna fracture [23].
• Loss of range of movement in both the flexion extension and pronosupination axis is reported with average extension lag of 30 degrees, with flexion up to 117 degrees, and pronation from 58° to 52° supination on average [23].
• Reported in one third or more of press-fit proximal head arthroplasties, loosening causes significant proximal radial osteolysis and generally necessitates removal [57].
• In the setting of neck comminution, small plates or cerclage wires should be available to allow for neck reconstruction and the use of a standard prosthesis [51].
• A long-stem bipolar prosthesis should be available in the uncommon situation where reconstruction of the radial neck to accept a standard prosthesis is not possible [51].

Complications

Specific Complications and Failure Modes

• Overlengthening of the radial column is a recognized complication of radial head replacement [1].
• Surgical factors that predispose to early failure include over-stuffing, improper alignment, inadequate fixation, or persistent instability [23].
• Persistent instability may result from inadequate soft tissue repair or inadequate management of an associated ulna fracture [23].
• Hospital factors that can lead to reoperation include the use of a silicone implant [23].
• Patient factors that can lead to reoperation include younger age, fewer co-morbidities, and delay to surgery [23].
• The use of stem auto-expansion as a mode of obtaining primary fixation appears to be an effective solution for reducing the risk of painful loosening [40].

Revision and Removal Rates

• The best estimate for the revision rate of radial head arthroplasty is 2 per 100 person years of follow-up [23].
• Many revision cases may not be reported in the existing literature [23].
• Most removals of radial head prostheses were performed to manage elbow stiffness and heterotopic ossification rather than due to implant malfunction [41].
• Radial head arthroplasty results in modest complication and revision rates at long-term follow-up [68].

Clinical Presentation of Failure

• Patients with failed radial head implants can present with persistent pain, stiffness, infection, or instability of the radiocapitellar joint, ulnohumeral joint, or both [23].
• Loss of range of movement in the flexion-extension axis is reported with an average extension lag of 30 degrees [23].
• Loss of range of movement in the flexion-extension axis is reported with flexion up to 117 degrees [23].
• Loss of range of movement in the pronosupination axis is reported with average pronation from 58 degrees to 52 degrees supination [23].
• A common feature of patients presenting with failed radial head implants is delay to initial surgery [23].

Comparative Complication Profiles

• Mason type 3 radial head fractures treated with open reduction and internal fixation exhibit a higher risk of complications compared to those treated with radial head arthroplasty [21].
• Radial head arthroplasty is associated with fewer complications compared to radial head excision [9].
• Radial head replacement had fewer adverse events than open reduction and internal fixation for Mason type III radial head fractures in the short-term in a Chinese population [30].
• The evidence regarding the comparative adverse event rates between radial head replacement and open reduction and internal fixation is of low quality and results may not apply in the longer term or more generally [30].
• Associated complication rates for the EVOLVE radial head prosthesis are low [7].

Recovery

• A minimum follow-up of three years is recommended to improve the reproducibility of results in radial head arthroplasty studies [3].
• A consensus on the definition of reasons for failure is required to improve the reproducibility of results in radial head arthroplasty studies [3].
• Use of a standard surgical protocol for elbow dislocations with radial head and coronoid fractures restores sufficient elbow stability to allow early motion postoperatively [35].
• The restoration of sufficient elbow stability via surgical protocol enhances the functional outcome [35].
• The goals of current management are aimed at restoring normal anatomical and biomechanical function [42].
• Treatment is dictated by fracture type, stability, and ligamentous integrity [42].

Key Evidence

• [L4] The review aims to shed light into overlengthening as a complication of radial head replacement and to help identify and treat it. [1] (10.1007/s00402-020-03619-9)
• [L5] Clinical outcome studies of metallic radial head arthroplasty systems indicate that head replacement is a reasonable option to offer patients with comminuted radial head fractures and complex elbow trauma. [2] (10.1016/j.jhsa.2005.12.005)
• [L1] The reproducibility of results would be improved by using a minimum follow-up of three years combined with a consensus of the definition of the reasons for failure after radial head arthroplasty. [3] (10.1302/0301-620x.99b12.bjj-2017-0543.r2)
• [L4] Due to the variety of implant designs and limited evidence, the current data provide no evidence for a specific radial head prosthesis design. [4] (10.1302/2058-5241.4.180099)
• [L1] Implant fixation type does not appear to affect functional outcomes of radial head arthroplasty. [5] (10.1016/j.jse.2018.07.032)
• [L5] Adequate knowledge of the surgical indications, types of implants, and surgical technique are essential for a satisfactory outcome when a radial head prosthesis is used for the treatment of nonreconstructable radial head fractures. [6] (10.5435/jaaos-22-10-633)
• [L2] Midterm outcomes of EVOLVE radial head prosthesis are satisfactory, and associated complication rates are low. [7] (10.1177/1758573219850111)
• [L5] Primary radial head replacement is preferred over failed internal fixation because the latter typically does not result in a pain-free elbow due to damaged cartilage surfaces. [8] (10.1016/j.hcl.2004.06.003)
• [L4] Better outcomes are reported for radial head arthroplasty in terms of elbow stability, range of motion, pain, and fewer complications compared to radial head excision. [9] (10.1155/2018/4020625)
• [L3] Anatomic radial head replacement has a risk of radiographic technical mistakes that correlate to poorer outcomes. [10] (10.1016/j.jseint.2026.101671)
• [L5] Most fractures of the radial head are stable and managed non-operatively with good long-term results, while displaced unstable fractures require restoration of radiocapitellar contact via reconstruction or prosthetic replacement to prevent elbow instability. [11] (10.1302/0301-620x.95b2.29877)
• [L5] [12] (10.1016/j.jhsa.2014.10.029)
• [L4] The preferred treatment for failed radial head arthroplasty depends mainly on the chondral condition and stability of the elbow joint. [13] (10.1302/2058-5241.5.190055)
• [L4] Radial head replacement is recommended for comminuted fractures with satisfactory medium- and long-term results, though bipolar-cemented implants show lower revision rates. [14] (10.1016/j.injury.2013.09.019)
• [L1] Recommendations for surgical treatment of radial head and neck fractures according to the Mason classification can now be given with the best available evidence. [16] (10.1016/j.injury.2013.04.003)
• [L1] Mason type 3 radial head fractures treated with open reduction and internal fixation exhibit a higher risk of complications compared to those treated with radial head arthroplasty. [21] (10.1016/j.jseint.2024.08.180)
• [L5] The ligaments have the most marked influence on stability, particularly when the upper limb is positioned such that valgus and varus gravity loads are applied to the elbow. [22] (10.1016/j.jse.2004.09.034)
• [L5] [23] (10.1177/1758573219876921)
• [L4] Unstable or unpredictable fixation of complex radial head fractures should probably be treated with prosthetic replacement to avoid instability of the forearm or elbow. [24] (10.1016/j.jse.2010.11.011)
• [L5] [26] (10.1530/eor-24-0035)
• [L1] Radial head replacement had better elbow function and fewer adverse events than ORIF for Mason type III RHF in the short-term in Chinese population, but evidences are of low quality and results may not apply in the longer term or more generally. [30] (10.1016/j.otsr.2015.06.015)
• [L4] Use of the surgical protocol restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. [35] (10.2106/jbjs.d.02933)
• [L1] Based on the current evidence, conservative management of isolated Mason II radial head fractures yields favorable therapeutic outcomes with a low incidence of complications. [36] (10.1186/s13018-024-05039-6)
• [L1] The use of stem auto-expansion as a mode of obtaining primary fixation in radial head arthroplasty appears to be an effective solution for reducing the risk of painful loosening. [40] (10.1007/s00264-018-4070-0)
• [L1] Most removals were performed to manage elbow stiffness and heterotopic ossification rather than due to implant malfunction, suggesting acceptable mid-term longevity. [41] (10.1016/j.jhsa.2017.08.031)
• [L5] The goals of current management are aimed at restoring normal anatomical and biomechanical function, with treatment dictated by fracture type, stability, and ligamentous integrity. [42] (10.1016/j.hcl.2007.01.009)
• [L4] [61] (10.1016/j.otsr.2015.06.026)
• [L4] Our systematic review established that RHA results in satisfactory clinical outcomes and modest complication and revision rates at long-term follow-up, despite high levels of radiologic degenerative changes over the same period. [68] (10.1016/j.jse.2021.03.142)

References

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