Radial head fractures without associated bony or ligamentous injury can be safely treated with internal fixation, if possible, or arthroplasty if nonreconstructable. However, nonreconstructable radial head fractures in association with elbow dislocation and/or ligamentous injury in the elbow or forearm represent a specific subset of injuries that requires restoration of the radiocapitellar articulation for optimal function. The purpose of this article was to summarize the indications for radial head arthroplasty and discuss the reported outcomes.
Key points
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Radial head fractures without associated bony or ligamentous injury can be safely treated with internal fixation, if possible, or arthroplasty if unreconstructable.
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Radiocapitellar contact, through either repair or replacement of the radial head, is an essential aspect of proper management for radial head fractures with associated injuries.
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Excision of an unreconstructable radial head should be done with caution, as it can result in elbow or longitudinal forearm instability.
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The ability to generalize outcomes after radial head arthroplasty is limited by the heterogeneity of indications, injury severity, type of implant, and choice of outcome measurements.
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The treatment of radial head fractures with associated ligamentous and/or bony pathology using radial head arthroplasty has been reported to result in good or excellent outcomes in 76% to 94% at long-term follow-up.
Introduction
The treatment of comminuted radial head fractures remains controversial. Radial head excision can be successfully performed in isolated radial head injuries; however, radial head excision also has been noted to result in pain, instability, proximal migration of the radius, decreased strength, and osteoarthrosis in some cases. These negative outcomes are related to the critical role the radial head plays in force transmission and stability of the elbow. The radial head transmits up to 90% of the force across the elbow and functions as an important secondary stabilizer to valgus stress. This critical role is emphasized when radial head fractures are associated with additional ligamentous and bony pathology, which is the case in nearly one-third of radial head fractures. The likelihood of associated injuries strongly correlates with the severity of the radial head fracture, increasing from 20% in nondisplaced fractures to 80% in comminuted fractures.
These findings have led some to believe that restoration of radiocapitellar contact, through either repair or replacement of the radial head, is an essential aspect of proper management. Failure to address the radiocapitellar articulation may lead to valgus elbow instability, elbow stiffness, proximal radial migration, degenerative changes at the wrist and elbow, and chronic pain. However, degenerative changes of the capitellum due to wear remains a concern with the use of implant arthroplasty. Radial head fractures are a common injury, with an incidence of 30 per 100,000 persons per year. Previous series found radial head fractures to account for 1% to 5% of all fractures and 33% to 75% of all elbow fractures. Therefore, understanding the proper management of these fractures is essential.
Since Speed performed the first documented radial head arthroplasty in 1941, implant materials have included acrylic, silicone, cobalt-chromium, titanium, and pyrocarbon. The use of silicone implants has become less popular because of their inability to reconstitute normal biomechanics, resulting in suboptimal wear characteristics, particulate debris, implant failure, and elbow instability. Metallic implants are now commonly used and published reports have documented promising results. The specific type of implant used, however, is likely less important than adhering to proper indications and technique. The purpose of this article was to review the indications and outcomes of radial head arthroplasty.
Introduction
The treatment of comminuted radial head fractures remains controversial. Radial head excision can be successfully performed in isolated radial head injuries; however, radial head excision also has been noted to result in pain, instability, proximal migration of the radius, decreased strength, and osteoarthrosis in some cases. These negative outcomes are related to the critical role the radial head plays in force transmission and stability of the elbow. The radial head transmits up to 90% of the force across the elbow and functions as an important secondary stabilizer to valgus stress. This critical role is emphasized when radial head fractures are associated with additional ligamentous and bony pathology, which is the case in nearly one-third of radial head fractures. The likelihood of associated injuries strongly correlates with the severity of the radial head fracture, increasing from 20% in nondisplaced fractures to 80% in comminuted fractures.
These findings have led some to believe that restoration of radiocapitellar contact, through either repair or replacement of the radial head, is an essential aspect of proper management. Failure to address the radiocapitellar articulation may lead to valgus elbow instability, elbow stiffness, proximal radial migration, degenerative changes at the wrist and elbow, and chronic pain. However, degenerative changes of the capitellum due to wear remains a concern with the use of implant arthroplasty. Radial head fractures are a common injury, with an incidence of 30 per 100,000 persons per year. Previous series found radial head fractures to account for 1% to 5% of all fractures and 33% to 75% of all elbow fractures. Therefore, understanding the proper management of these fractures is essential.
Since Speed performed the first documented radial head arthroplasty in 1941, implant materials have included acrylic, silicone, cobalt-chromium, titanium, and pyrocarbon. The use of silicone implants has become less popular because of their inability to reconstitute normal biomechanics, resulting in suboptimal wear characteristics, particulate debris, implant failure, and elbow instability. Metallic implants are now commonly used and published reports have documented promising results. The specific type of implant used, however, is likely less important than adhering to proper indications and technique. The purpose of this article was to review the indications and outcomes of radial head arthroplasty.
Classification
The Mason classification is the most commonly used classification system for radial head fractures. Type I fractures are nondisplaced, Type II fractures are displaced partial head fractures, and Type III fractures are displaced fractures that involve the entire radial head. Johnston modified the Mason classification, by adding a fourth type, defined as a fracture of the radial head with associated elbow dislocation. Broberg and Morrey further modified the Mason classification by defining the amount of fracture displacement. A Type I fracture is defined as less than 2 mm of displacement. A Type II fracture has 2 mm or more displacement and/or involves 30% or more of the joint surface. A Type III fracture is a comminuted fracture and a Type IV fracture is any of the previously mentioned types with a concomitant elbow dislocation.
In an attempt to better guide operative treatment, Hotchkiss modified the Mason classification with respect to mechanical block to motion. Type I fractures are defined as nondisplaced fractures or minimally displaced marginal lip fractures (<2 mm displacement) that do not block motion and can be treated nonoperatively. Type II fractures are displaced fractures (usually >2 mm) that may have a mechanical block to motion or are incongruous but do not have severe comminution. Type II fractures are often amenable to open reduction and internal fixation. Type III fractures are comminuted fractures that are unable to be repaired and are excised or undergo radial head arthoplasty.
Although the Mason classification and its modifications are well accepted and commonly used, Ring found that the radiographic parameters used to define displacement have been an unreliable indicator of instability. He noted that the presence of more than 3 fragments has a higher correlation with poor results following open reduction and internal fixation. Also, radial head fractures associated with elbow dislocations indicate a complex injury pattern and should alert the surgeon to associated fractures and ligamentous injuries that may also result in a less optimal outcome.
Indications for radial head arthroplasty
Despite numerous studies and advances in technology, controversy still exists over the indications for open reduction and internal fixation versus radial head arthroplasty for comminuted radial head fractures. Historically, excision of the radial head was indicated in comminuted radial head fractures that were deemed unreconstructable. Reports of proximal radial migration associated with an interosseous membrane injury, an Essex-Lopresti lesion, have led surgeons to exercise caution when considering primary radial head excision for acute radial head fractures. Associated ligamentous and bony injuries around the elbow represent a contraindication to excision of the radial head because of role of the radial head as the primary stabilizer to valgus stress.
Radial head arthroplasty is indicated in the following situations ( Box 1 ): (1) an acute comminuted fracture in which satisfactory reduction and stable fixation cannot be obtained ; (2) complex elbow injuries that involve greater than 30% of the articular rim of the radial head, which cannot be reconstructed; (3) fractures with 3 or more fragments or significant comminution ; (4) instability of the elbow after radial head excision ; (5) patients who present in a delayed manner with persistent pain and instability from radial head primary resections, malunions, or after complex elbow fracture-dislocations involving the radial head ; (6) suspected Essex-Lopresti lesion ; (7) associated terrible triad injuries ; (8) unreconstructable radial head fractures with concomitant medial collateral ligament injury, interosseous membrane injury, or elbow dislocation.
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Acute comminuted fracture in which satisfactory reduction and stable fixation cannot be obtained
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Complex elbow injuries that involve greater than 30% of the articular rim of the radial head, which cannot be reconstructed
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Fractures with 3 or more fragments or significant commination
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Instability of the elbow after radial head excision
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Pain and instability from radial head primary resections, malunions, or after complex elbow fracture-dislocations involving the radial head
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Suspected Essex-Lopresti lesion
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Associated terrible triad injuries
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Unreconstructable radial head fractures with concomitant medial collateral ligament injury, interosseous membrane injury, or elbow dislocation
Contraindications to radial head arthroplasty include (1) nondisplaced or minimally displaced radial head fracture with no mechanical block to motion and no elbow instability, (2) active infection in or around the elbow joint, (3) neurologic injury preventing meaningful use of the elbow, (4) stable elbow arthrodesis, and (5) congenital radial head dislocation.
Outcomes
The ability to generalize outcomes after radial head arthroplasty is limited by the heterogeneity of indications, injury severity, type of implant, and choice of outcome measurements. Most published series contain a heterogeneous patient population ranging from isolated fractures to comminuted fractures with associated elbow dislocations and/or terrible triad injuries. The timing of radial head arthroplasty also varies in the literature, with some investigators performing surgery within a week of injury and others in delayed fashion, even several years after the initial injury.
Cobalt-chromium
The first radial head arthroplasty was performed in the 1940s using cobalt-chromium caps in a canine model, followed shortly thereafter by use in humans. Ten years later, Carr and Howard reported on the use of the cobalt-chromium cap in 12 cases of uncomplicated radial head fractures. Silastic and titanium implants temporarily supplanted cobalt-chromium as the material of choice in radial head implants, but most recent series have used cobalt-chromium implants.
Two studies have reported mean follow-up of longer than 8 years. Popovic and colleagues reviewed 51 patients with a comminuted fracture of the radial head treated with either monoblock or modular radial head replacement. The radial head fractures were associated with an elbow dislocation in 34 patients and a Monteggia fracture in 6. At an average follow-up of 8.4 years (range 4–13 years), the investigators reported an average Mayo Elbow Performance Score (MEPS) of 83 (range 59–95) with 39 (76%) good or excellent results. Radiographic assessment found 37 (73%) patients with progressive osteolysis around the implant. Reported mean arc of elbow flexion-extension was 115°. With respect to pain, 41 (80%) patients reported no pain or mild pain with activities. Burkhart and colleagues retrospectively reviewed 17 patients with an average follow-up of 106 months (range 78–139 months). Acute radial head replacement was performed in 9 patients and delayed replacement was performed in 8 patients. The injury patterns were heterogeneous, with 4 patients having isolated nonreconstructable radial head fracture, 2 patients had associated elbow dislocations, 3 patients had a terrible triad, 6 patients had Monteggia fractures, and 1 patient had an Essex-Lopresti lesion. Despite the complex injury patterns, the average MEPS score was 90.8, with 16 (94%) good or excellent results. The investigators found no difference in outcomes between primary and delayed implantation. The mean DASH score was 9.8, mean flexion arc was 124° (range 110–150°), and extension deficit was 21° (range 0–40°). Heterotopic ossification developed in 12 patients. Complications occurred in 5 patients, prosthetic dislocation in 2, and capitellar erosion in 3.
Multiple studies have reported satisfactory outcomes at medium-term follow-up. Judet and colleagues reviewed 12 patients with mean follow-up of 49 months. Acute radial head replacement was performed in 5 patients and delayed replacement in 7 patients after failed excision. All patients who underwent acute reconstruction had good results, based on the Brodberg and Morrey Index, compared with no good or excellent results in the delayed reconstruction group. These results could be misleading, however, as the delayed reconstruction group had undergone between 2 and 4 procedures per patient before reconstruction. Flinkkila and colleagues reviewed 35 patients, at mean follow-up of 53 months (range 12–106 months), with an acute radial head fracture and associated unstable elbow injury treated with a modular uncemented press-fit cobalt chromium radial head replacement. The associated elbow injury was a terrible triad in 19 patients. The average MEPS score was 86 (range 40–100), resulting in good or excellent results in 26 (74%) patients. The investigators removed 9 implants (26%), and 4 patients required excision of heterotopic ossification. Knight and colleagues performed a retrospective review of 31 patients treated with a cobalt-chromium implant for comminuted fractures of the radial head. The radial head fracture was associated with an elbow dislocation in 21 patients. The investigators noted a successful result in 24 (77%) patients with mean follow-up of 4.5 years. Two of the implants required removal because of painful loosening and 7 cases were complicated by nonprogressive radiolucencies around the prostheses. Brinkman and colleagues treated 11 patients who failed open reduction internal fixation or excision with delayed radial head arthroplasty at a mean of 8 years after initial injury. The investigators reported 100% good or excellent results at mean follow-up of 2 years (range 1–4 years).
Several studies have reported acceptable short-term outcomes. Grewal and colleagues prospectively evaluated 26 patients in whom an unreconstructable radial head fracture had been treated with a modular radial head prosthesis. At 24-month follow-up, 16/26 (62%) patients were rated as good or excellent, with an overall average MEPS score of 83 points. Mean elbow flexion was 138° and average DASH 24.4 (±21.4). Radiographic lucency was present around 13 (50%) implants. Mild posttraumatic arthritis was evident in 5 (19%) and heterotopic ossification was present in 6 (23%). Chapman and colleagues reviewed 16 patients, at an average follow-up of 33 months. Of this group, 8 patients underwent acute reconstruction and 8 patients underwent delayed reconstruction. In the acute group, the investigators found 3 patients with an excellent result and 5 patients with a good result. Despite 5 fracture-dislocations in the acute group compared with all ground-level falls and no fracture-dislocations in the chronic group, the acute group performed better on the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Lim and Chan reviewed 6 patients after radial head arthroplasty with a cemented cobalt-chromium prosthesis at an average follow-up of 30 months. Despite good pain relief with an average visual analog scale (VAS) score of 1.8, the average flexion arc was found to be 100° and 4/6 (67%) experienced a good or excellent result according to the Brodberg and Morrey Performance Index. Chien and colleagues reviewed 13 patients who underwent radial head arthroplasty at mean follow-up of 38 months (range 20–70). The investigators found good to excellent results in 11 (85%) patients, based on MEPS, with 2 patients undergoing implant removal. Doornberg and colleagues retrospectively reviewed 27 patients treated with a modular prosthesis. The radial head fracture was associated with an elbow dislocation in 10 patients and a terrible triad in 13. At final follow-up, the average arc of motion was 111° (range 35–155°), 17 (68%) of 25 had radiographic evidence of lucency. The average MEPS score was 85 (range 30–100), resulting in 22 (81%) of 27 good or excellent results. The average DASH score was 17 (range 0–82). Radiographic evidence of lucency around the stem was present in 17 (68%) and radiographic evidence of arthritis was present in 12 (44%).
Silastic
Silicone implants were commonly used until concerns arose regarding suboptimal wear characteristics, particulate debris, and implant failure with repetitive compressive loads. The compressibility of silicone makes it unable to adequately restore the biomechanics of the elbow and may result in progressive osteoporosis of the capitellum. An early series by Mackay and colleagues found satisfactory results in 17 (94%) of 18 patients, but noted hardware failure in 3 patients within 26 months. Less promising results were noted by Morrey and colleagues and Swanson and colleagues. Morrey and colleagues reported 5 (29%) failures in 17 patients, finding that all of the failures occurred in patients who underwent delayed reconstruction, at an average of 24 months after radial head excision. Swanson and colleagues compared 12 patients with delayed arthroplasty after radial head resection with 6 patients with acute arthroplasty and found consistent radial shortening with a correlation to decreased forearm supination in the delayed replacement group compared with no shortening in the acute group. The investigators found the best results when the implant was used primarily in fractures, to maintain the normal mechanical relationships. A recent series by Maghen and colleagues retrospectively reviewed 23 patients with unreconstructable radial head fractures who were treated with silastic radial head arthroplasty and concomitant repair and/or reconstruction of the medial ulnar collateral ligament and/or lateral ulnar collateral ligament. At an average follow-up of 70 months (range 16–165), the investigators found an average arc of motion of 134°, an average DASH of 11.8 (range 0–56), and an average Mayo Elbow Performance Score (MEPS) of 88.9 (range 45–100). The investigators argued that silastic implants may still be a reasonable implant option if associated injuries are appropriately treated to minimize reliance on the implant for stability.
Titanium
Harrington and Tountas published one of the first series using titanium radial head prosthesis in 1981. The investigators reported good or excellent results in 14 (93%) of 15 patients at average follow-up of 6.9 years. In an update of their series, Harrington and colleagues reported 16 (80%) of 20 good or excellent outcomes, based on the Mayo Clinic Functional Index, at mean follow-up of 12.1 years (range 6–29 years). The series included 13 patients with Mason IV injuries. Only 6 (30%) of 20 were completely pain free at final follow-up, but an additional 10 had pain only with continuous activity. The investigators note degenerative changes of the capitellum in 9 patients (45%). Shore and colleagues studied 32 patients, with mean follow-up of 8 years (range 2–14 years), treated with delayed radial head arthroplasty an average of 2.4 years after the injury. The radial head fractures were associated with an elbow dislocation in 17 patients and terrible triad in 7 patients. The average MEPS score was 83, with 21 (66%) obtaining good or excellent results. Posttraumatic arthritis was observed in 74%. The MEPS score in 11 patients with moderate posttraumatic arthritis was 79 compared with 93 in 10 patients with mild arthritis. In contrast to other series, Shore and colleagues did not remove any implants.
Moro and colleagues retrospectively reviewed 25 patients with 10 Mason III and 15 Mason IV radial head fractures, treated with acute radial head arthroplasty using a noncemented titanium prosthesis. At mean follow-up of 39 months (range 26–58 months), the investigators noted 16 (64%) good or excellent results with 5 (20%) patients demonstrating radiographic evidence of posttraumatic arthritis. Heterotopic ossification was found in 8 (32%) patients. Ashwood and colleagues studied outcomes in 16 patients treated with a titanium radial head prosthesis. The average MEPS score at final follow-up (average 2.8 years) was 87 (range 65–100) with 13 (81%) obtaining good or excellent results. The average VAS score was 1.7 (range 0–4.5) and 7 of 9 employed patients were able to return to work. On average, patients lost 15° of extension and 10° of flexion compared with the uninjured side.
Pyrocarbon
Pyrocarbon radial head prostheses have been introduced as an alternative to metallic implants. Ricon and colleagues performed a retrospective analysis of 28 patients with Mason III radial head fractures treated with a pyrocarbon radial head prosthesis. The radial head fracture was associated with an elbow dislocation in 23 patients. At an average follow-up of 23 months, patients had an average MEPS score of 92 (range 70–100). The mean flexion-extension arc was 105° (range 65–130). Although these outcomes are comparable to those achieved with cobalt-chromium and titanium prostheses, enthusiasm should be tempered until longer-term follow-up data are available.
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