Epidemiology
Fractures of the radial head account for approximately 3% of all fractures and are the most common fracture of the elbow in adults [1, 2]. A retrospective epidemiological study conducted in the Netherlands showed that the incidence of radial head fractures was 2.8 cases per 10,000 person-years [3]. The male to female ratio was 2:3 and the mean age of onset was 43 years.
Anatomy and biomechanics
The elbow joint consists of three mutually independent joints: the humeral ulnar joint, the humeral radial joint, and the superior ulnar radial joint (see Appendix). The medial collateral ligament (MCL) limits valgus and the lateral collateral ligament (LCL) prevents valgus and postero-lateral instability [4, 5]. The radial head serves as an important stabilizing structure against valgus, axial, and postero-lateral rotational stresses.
In larger fracture fragments of the radial head, the concave-compression mechanism is disrupted and painful heterogeneity can occur, thus affecting the stability and kinematics of the humeral-radial joint. Stability must be restored by open reduction and internal fixation (ORIF) or radial head replacement [6-8].
Even when the ligamentous structures are intact, removal of the radial head can still affect the stability of the elbow joint, and normal kinematics can be repaired by radial head replacement [9, 10]. When combined with an MCL injury, radial head resection can further exacerbate valgus instability, when radial head replacement can restore stability to a state similar to that of a normal radial head [9, 11, 12]. Cadaveric studies have found that bipolar radial head prostheses are less stable than single-stage prostheses, suggesting that single-stage prostheses should be preferred in the treatment of complex elbow instability [13, 14].
Some studies have measured humans and found that the radial head is irregularly oval in shape [11, 15]. The radial head has a degree of offset relative to the radial neck, which is important because, at present, most radial head prostheses as well as plates are not designed with this particular anatomical morphology in mind [16].
The radial head is associated with a small sigmoid notch at the proximal end of the ulna, part of which participates in the joint and the other part does not. The area that does not participate in the joint occupies approximately 110° of arc and is located in the area from 65° anterolateral to 45° posterolateral in the neutral forearm position [17-19].
Fracture staging system
The ideal staging of radial head fractures and the characteristic description of them remain controversial [20].Mason classified radial head fractures into three types: nondisplaced, displaced, and displaced comminuted [1].Broberg and Morrey modified this staging to take into account the degree of displacement as well as the size of the fracture mass [21]. However, these typing systems have poor interobserver credibility and make it difficult to guide treatment [22-24].
We suggest that for radial head fractures the main considerations are partial intra-articular (wedge) or complete intra-articular, no displacement or displacement, and whether the fracture is comminuted. Treatment is selected based on these types.
Medical history and physical examination
Information about the patient’s age, occupation, time of injury, and course of treatment is recorded. In cases with a history of dislocation or instability, the site of pain and the mechanism of injury can help determine the concomitant injury. The presence or absence of neurological symptoms should be noted. Medical, surgical, and anesthesia related conditions, as well as psychosocial history, medication history, and allergy history must be thoroughly evaluated.
A thorough physical examination, including force lines of the upper extremity and elbow joint, soft tissue injuries, and bony injuries should be in place. Laterally, structures such as the lateral epicondyle, humeral tuberosity, radial head and radial neck should be palpated; medially, the medial epicondyle, elevated tuberosity and proximal ulna should be palpated. The wrist joint and lower ulnar radial joint should also be noted during the examination to rule out concomitant distal injuries. Elbow motion if limited may be considered for evaluation after removal of the hematoma intra-articular injection of local anesthetic medication [24, 25]. If there is mechanical blockage of forearm rotation, surgical treatment should be considered.
Concomitant injury
Fractures with minimal or no displacement are generally not associated with other injuries [25]. Displaced, unstable, or comminuted radial head fractures have a high incidence of concomitant other fractures or ligamentous injuries [26, 27]. Relatively complex radial head fractures are usually seen in: posterior dislocation, LCL or MCL tears, humeral tuberosity fractures, terror triad, posterior dislocation of trans-hawk fractures (posterior Monteggia fractures), and interosseous membrane tears (Essex-Lopresti injuries) [26]. High-energy injuries often result in comminuted radial head fractures with fractures of the distal radius, navicular bone, and proximal humerus [14, 28, 29].
Imaging evaluation
Routine frontal and lateral and oblique films of the elbow are taken, whereas a CT scan may be required to more clearly show the relevant features of the radial head; however, CT does not improve staging [20].CT is helpful in determining whether there are concomitant coronoid and humeral tuberosity fractures. If there is obstruction during elbow motion and no mechanical factors are found on X-ray, CT can help to clarify the pathologic pattern. If the cause cannot be determined by CT either, the possibility of cartilage fracture mass entrapment should be considered [30].
Treatment
Treatment of radial head fractures includes both nonoperative and operative approaches. Surgical approaches include fracture block excision, radial head resection, radial head replacement, and ORIF. The indications for surgery remain controversial among elbow surgeons.
Non-surgical treatment
Indications
Nonoperative treatment of radial head fractures is generally indicated for fractures with no displacement or simple displacement but no obstruction to motion [21, 31] (Figures 1-A and 1-B). There is still controversy as to what degree of displacement and how large a fracture fragment can be treated nonoperatively with good clinical outcomes after activity. Most scholars recommend non-operative treatment for fracture extent <25% of the radial head with <2 mm collapse. Surgery should be an option if the fracture mass is large, significantly displaced, or if there is a bone mass obstructing joint motion [1, 21, 25, 31-41]. It has also been reported that non-operative treatment is also an option when the fracture is well displaced but has no effect on rotational function, and good results can be obtained by allowing early activity [32].
Figures 1-A and 1-B Female, 18 years old, with a partial intra-articular fracture with no obstruction to joint movement. Figure 1-A shows the orthopantomogram at the time of consultation. Figure 1-B shows the orthopantomogram one year after non-surgical treatment. The patient’s joint range of motion was fully restored and function was excellent.
Treatment
Early activity is fundamental to prevent joint stiffness. A certain period of braking, usually 5-7 days, is still necessary for patients with pain. The affected limb is immobilized in a neck and wrist sling (collar and cuff) and active flexion and extension, anterior and posterior rotation exercises are started with guidance. The neck and wrist sling was removed after pain relief. The position of the fracture is assessed after two weeks and improvement in joint motion is recorded. complete or near complete restoration of elbow mobility is required at 6 weeks. If joint stiffness persists, passive flexion and extension under the direction of a physical therapist and gradual immobilization with a static splint are recommended.
Clinical Outcomes
Long-term outcomes of non-surgical treatment are good. In one study [32], it was reported that 40 of 49 patients had no complaints of discomfort after 19 years, but 6 patients had poor results after radial head resection. In another study [31], 32 displaced radial head fractures were treated conservatively with 21 years of follow-up and 29 had excellent or good clinical outcomes, none of which were treated surgically. 27 patients had degeneration of the injured limb on imaging but were asymptomatic, and only one patient had degeneration of the healthy elbow joint. If non-operative treatment fails, radial head resection or replacement are both better treatment options [42, 43].
In a retrospective study [44], comminuted fractures with displaced radial heads were treated non-operatively and fixed surgically, and a comparison revealed similar functional outcomes in both groups.
Non-operative treatment may present with painful deformity healing with popping, fracture displacement, non-union, or traumatic arthritis. Further treatment options include fracture block resection, radial head osteotomy, radial head resection, and radial head replacement [45].
Surgical treatment
Surgical access
Surgical treatment can be performed with either a lateral or posterior incision, depending mainly on the operator’s custom and the concomitant injury (see Appendix). The posterior lateral incision is chosen for less penetration of the cutaneous nerve and is more aesthetic, but the risk of hematoma formation as well as flap necrosis is higher [46]. The patient is placed in the supine position and the injured limb is secured to the chest with a forearm cushion, or an upper extremity table can be applied. If the LCL is intact, it can be exposed by splitting the approach of the common extensor tendon, taking care to protect the lateral ulnar collateral ligament (LCL) and incising the joint capsule anteriorly to it, which facilitates anterior exposure. If the LCL is broken, separation can be performed in the gap between the ulnar collateral ligament and the elbow muscle more posteriorly [45]. The most significant risk of lateral elbow access is the posterior interosseous nerve [47]. To reduce the risk of interosseous posterior nerve injury, the forearm should be rotated as far forward as possible intraoperatively to avoid excessive pulling forward and medially.
After intraoperative management of the radial head and other concomitant fractures (see Appendix), attention is given to repairing the LCL injury. The isometric point of the LCL starting point and the axis of flexion and extension is determined anteriorly below the center of the humeral tuberosity. The LCL and the starting point of the common extensor tendon are repaired with a thick non-absorbable braided wire. The forearm is placed in various positions to check elbow joint stability, and the wound is then closed layer by layer. Associated concomitant injuries such as the coronoid process, proximal ulna, or MCL are repaired if necessary.
Fracture block resection
Indications: Fracture block resection is mainly indicated for displaced small fracture blocks that form a mechanical block and impede elbow joint motion. For larger fracture blocks, ORIF should be considered if technically possible. fracture block resection should not exceed 25% of the radial head, otherwise it may easily lead to painful popping or symptomatic instability [6, 48].
Surgical approach: performing fracture block resection can be done through open surgery or arthroscopy. After patient anesthesia is reached, the stability of the elbow joint is checked. A radial head dislocation impinging on the humeral tuberosity resulting in a posterior lateral humeral tuberosity fracture can be resected if the fracture involves <25% of the articular surface of the humeral tuberosity. In order to avoid posterior posterolateral elective instability, exact repair of the posterolateral ligamentous structures is important [49, 50].
Clinical results: the relevant literature is scarce, and in a group of case reports including 2 patients, the results were good [40]. However, in other studies [33, 51], the results were less favorable. excellent results were obtained in 17 of 33 patients, and of course, the study performed resection in patients with fractures involving >33% of the radial head. To our knowledge, the clinical results of arthroscopic fracture block resection have not been reported.
Further treatment options include radial head resection, radial head replacement, and ligament reconstruction.
Radial head resection
Indications: Radial head resection is mainly used to treat comminuted fractures that are simply displaced [52]. Radial head resection is only indicated in cases with a stable elbow joint and is not a routine treatment option considering that most comminuted radial head fractures are associated with other fractures and ligamentous injuries. Resection may be considered in patients with low functional requirements, associated with infection or failure of other treatment options. Subsequent radial head resection at a later stage has comparable clinical efficacy to primary resection [42].
Surgical approach: usually via an approach that splits the common extensor tendon (which can also be done arthroscopically), the radial head is exposed and the fracture mass of the radial head is removed as well as the bone above the cephalocervical union. The forearm is carefully assessed for rotation and the proximal radial stump is examined for impingement on the ulna. The stability of the forearm and elbow joint is examined (by imaging fluoroscopy if needed) to determine that a radial head prosthesis replacement is not required.
Clinical outcomes: several studies [37] have confirmed that radial head resection for simple comminuted fractures is an effective treatment. One study [53] reviewed 26 young patients under 40 years of age who were followed for at least 15 years after radial head resection; 24 patients had excellent outcomes and no one patient had a secondary procedure. In contrast, in non-randomized studies [41, 54, 55], displaced comminuted fracture ORIF was associated with better functional outcomes and lower incidence of arthritis in ORIF compared to radial head resection. The incidence of arthritis after radial head resection is higher, but long-term clinical outcomes are good [21, 37, 52, 53, 56, 57]. Less favorable outcomes, including limitations in active activities of daily living and work, have also been reported [58, 59] (see Appendix).
Early and late arthroscopic resection of the radial head has a good safety profile from the limited reports [60], yielding similar clinical outcomes to open resection and potentially faster healing times.
Exostosis and axial instability are the most common complications of radial head resection. Removal of the radial head can alter the kinematics of the elbow joint even if the ligamentous structures are intact, and radial head resection should be considered contraindicated in cases where ligamentous injuries are present [11]. The clinical outcome is somewhat better if the resection is ≤2 cm in extent [61]. If the extent of resection is too large, the likelihood of proximal ulnar radial impingement syndrome is greater [52, 59, 61]. Treatment of ulnar-radial impingement may consider surgical procedures such as arthroplasty or radial head replacement with transfer of the elbow muscle between the ulnar and radial bones [62].
Radial head replacement
Indications: radial head replacement is preferred for fractures with a comminuted displaced radial head for which stable fixation cannot be obtained with internal fixation surgery [Figures 2-A and 2-B]. Elbow instability due to radial head resection, malunion, or nonunion is also an indication for radial head replacement.
Figures 2-A and 2-B 60-year-old female with a radial head fracture, comminuted and displaced, with multiple fracture fragments. Figure 2-A shows the orthopantomogram at the time of presentation. Figure 2-B shows the orthopantomogram after the grouped radial head prosthesis replacement as well as the LCL repair. Note that the prosthesis is appropriately sized and well-proportioned compared to the medial humeral ulnar joint space.
Surgical approach: The specific surgical approach depends on the type of prosthesis chosen. For example, unipolar and bipolar prosthesis designs, grouped trial prostheses, and prostheses of different materials are currently used [14, 63-66].
The joint fracture fragment must be ensured to be thoroughly removed and the ideal diameter and length of the radial head prosthesis must be determined. The removed fragments of bone can be put back together on the operating table. A radial head prosthesis that is too large in diameter may lead to pain and arthritis, among other pathologies. Because of the oval shape of the radial head itself, if an axisymmetric prosthesis is chosen, the appropriate type can be determined based on the smaller diameter of the radial head [67].
The height of the resected radial head can be used to estimate the size of the prosthesis. Radial head prostheses that are too long or too short may lead to instability, pain, and arthritis [9, 11, 67-70]. To determine the correct length of the prosthesis, reference can be made to the articular relationship of the superior ulnar radial joint, where the prosthesis usually corresponds to the tip of the coronoid process at a distance of 1-2 mm [71]. The exact length of the prosthesis cannot be determined from the imaging correspondence between the lateral aspect of the lateral brachioradialis joint and the prosthesis due to the presence of normal anatomical variability in the individual [68, 72]. Normally, the medial humeral ulnar joint surfaces should be parallel, but it often takes much more than the length of the prosthesis to cause a widening of the lateral gap on imaging [Figures 3-A and 3-B]. Referring to the contralateral elbow radiograph, one can clearly determine if the radial head prosthesis is too long [68].
Figures 3-A and 3-B The best way to determine whether the radial head prosthesis is overgrown is to compare the contralateral radiograph (Figure 3-A) with the affected side (Figure 3-B). The figure shows that the overlength of the radial head prosthesis has widened the lateral humeral ulnar joint gap (yellow line).
After insertion of the trial mold, the mobility and stability of the elbow joint and forearm were examined under X-ray fluoroscopy. The stability of the lower ulnar radial joint and changes in the ulna were also examined. The final prosthesis installation was then completed according to the manufacturer’s recommended surgical approach.
CLINICAL OUTCOMES: The intermediate outcome of radial head replacement is good, but there are few data on long-term follow-up [14, 63, 69, 73-79]. Some studies [69, 73] have shown that early surgery (within 10 days of injury) tends to result in better clinical outcomes, while instability with ligamentous injury and without repair tends to be poorer.Grewal et al. reported 26 unreconstructable radial head fractures with radial head replacement, and the prosthesis was selected from a group-matched trial monopolar head with a loose compression-type stem (modular, monopolar prosthesis with a loose press-fit stem) [63]. Patient satisfaction was high, with a mean Mayo Elbow Performance Index (MEPI) score of 83 at the 2-year follow-up. 5 patients had mild asymptomatic manifestations of arthritis at the 2-year follow-up, and Zunkiewicz [14] et al. used a bipolar loose stem prosthesis in 29 patients with a mean follow-up of 34 months. , with a reported mean MEPI score of 92 and only two patients requiring secondary surgery: one with an unstable radial head prosthesis and the other with an overgrown prosthesis. Additional studies have evaluated pyrolytic carbon (pyrocarbon) prostheses, which had good short-term outcomes but had separation of the head and neck union [64, 65].
Complications of radial head replacement include humeral radial joint arthritis, prosthetic stem loosening, prosthesis failure or fracture, instability, dislocation, and infection [69]. X-ray translucent bands around the smooth prosthetic stem are common, with up to 94% reported in one study [80], but this phenomenon does not correlate significantly with forearm pain or elbow function. Prosthetic wear and osteolysis have been reported in fixed bipolar head prostheses. One study [81] included 51 patients with a mean follow-up of 8.4 years and 37 had progressive osteolysis on radiographs, suggesting that similar complications deserve attention if this type of prosthesis is chosen. However, there were no cases in which revision was performed because of prosthesis loosening. Erosion of the humeral tuberosity caused by the metal radial head does not correlate significantly with clinical symptoms, but the prosthetic process must be avoided [63, 69, 82]. It has been reported [79] that in 47 cases of radial head prosthesis failure, the most common cause of revision was aseptic loosening with pain, involving a total of 31 elbow joints. The number of cases in which revision was performed due to instability was 9 (19%). In another study [83] evaluating the clinical outcome of metal press-fit prostheses, 37 patients were followed up for a mean of 50 months, with early symptomatic loosening in 1/3 of the patients, 9 of whom had to have the prosthesis removed.
Incisional repositioning internal fixation
Indications: Indications for ORIF include displaced noncomminuted fractures with obstruction to rotation (Figures 4-A through 4-E.) ORIF is also commonly used to manage more complex, unstable fracture dislocations, when restoration of articular surface flatness is important to reestablish elbow stability. Articular surface fractures involving >30% of the radial head with a displacement >2 mm are considered indications for ORIF, but this remains controversial.
Figures 4-A through 4-E Male, 63 years old, partial intra-articular fracture with displaced radial head with coronoid fracture and elbow instability. Figures 4-A and 4-B, Frontal and lateral views at the time of the post-injury visit. Figure 4-C, CT scan showing a comminuted displaced coronoid fracture with a partially intra-articular fracture of the radial head and elbow instability. Figures 4-D and 4-E, incision and internal fixation of the radial head and coronoid fracture with transosseous reconstruction of the lateral collateral ligament, shown in a two-month postoperative orthoptic radiograph. The patient had a good functional outcome.
Surgical approach: The goal of treatment is to obtain a stable anatomic reposition, preserve soft tissue attachment to the bone mass, and allow early functional exercise if possible. Most partial intra-articular fractures of the radial head are located in the anterolateral 1/4, as was the case in 22 of 24 displaced radial head fractures in a group of case reports [84]. Therefore, if the LCL is intact, an approach that splits the common tendon of the extensor muscle is recommended, which allows better visualization of the fracture mass without accessing it through the more posterior gap between the ulnar carpal extensor and elbow muscles.
The periosteum of the fracture mass should be carefully protected intraoperatively to preserve its blood supply as much as possible and to avoid freeing the fracture mass from the elbow joint [85]. The repositioning is accomplished with the assistance of a small oral scraper or a small kerfing needle. The collapsed articular surface fracture block must be repositioned so that the radial head is restored to a complete plateau. If bone grafting is required, bone can be taken from the hawk’s beak or the lateral epicondyle of the humerus. Fixation of the fracture block is performed with headless or buried screws (1.5-2.5 mm).
The repositioning and fixation of a complete intra-articular fracture of the radial head is more challenging than that of a partial intra-articular fracture. Due to the high anatomic variability of the radial neck, there is no plate system that is well suited for fractures in this area, and even anatomic plates need to be shaped to accommodate the patient’s particular anatomic morphology [85]. Plates should be placed in a safe area of the nonarticular surface of the radial head, with care taken to minimize soft tissue stripping [18, 86].
For non-comminuted radial neck fractures, in addition to internal fixation with a steel plate, the bouquet technique (bouquet technique) with oblique drilling for placement of hollow compression screws can be applied [87]. A clinical study [88] showed that joint stiffness after screw fixation is much less common compared to plate fixation and that internal fixation usually does not need to be removed.
Clinical results: good clinical results are obtained with ORIF for non-comminuted displaced fractures [34, 35]. In one study [34], 20 radial head fractures (displaced [Mason type 2] or displaced comminuted [Mason type 3] fractures) were included, all underwent ORIF, with a mean follow-up of 7 years, and all had excellent or good clinical outcomes. In this study, the authors noted that for dislocated radial head fractures (Mason type 4), good outcomes were obtained in only four of the six patients, with the other two requiring reoperation. The results of other studies [40, 50] are similar to this study.Ring [26] concluded that it is difficult to obtain a satisfactory result with ORIF in more than three fracture blocks.
Adhesions, displacement of internal fixation, non-healing, degenerative arthritis and osteonecrosis may lead to joint stiffness [19, 26]. Non-surgical treatment can be considered first for adhesions. Nonunion, osteonecrosis, and arthritis may require radial head replacement, radial head resection, or total elbow arthroplasty.
Common complications of radial head fractures
Stiffness of the elbow joint as well as the forearm is not an uncommon complication [26]. Joint capsule contracture and adhesions are its common causes. A physical examination can clarify whether the motion endpoint is tender or stiff. If the endpoint is tender, after confirmation of fracture healing, it can be treated with passive distraction, static progressive splinting, or loose-tight spiral buckle splinting [89]. Non-operative treatment is often difficult to achieve success if the endpoint of motion is firm or has a hard feeling, suggesting mature contracture, impingement of the prosthesis or heterotopic ossification. If treatment fails, open or arthroscopic release of the contracture can often be successful. Risk factors for heterotopic ossification include floating elbow fractures, repeated multiple surgeries, delayed surgery, and prolonged braking. One study [90] showed an overall incidence of approximately 7% in all elbow fractures. Indomethacin and radiotherapy are commonly used to prevent heterotopic ossification, but their effectiveness in the elbow joint remains to be proven. One cautionary note if radiotherapy is administered is that it affects fracture healing [91].
If a patient has postoperative elbow pain, stiffness, and a translucent band around the built-up on radiographs, the possibility of infection should be considered. A history and physical examination, review of imaging data, reference to blood sedimentation and C-reactive protein, and arthrocentesis aspirate can help confirm the diagnosis. Acute postoperative infections in patients can be treated by irrigation, debridement, and application of antibiotics. In contrast, chronic infections should be treated by removal of the internal fixation, debridement, placement of antibiotic bone cement Spacer, and second stage revision with resection and plication or arthrodesis [92].
Injuries to the ulnar and posterior interosseous nerves are also more common [27, 55, 93]. Most nerve injuries are transient. If ulnar nerve symptoms worsen progressively, treatments such as ulnar nerve release and transposition may be considered and have been reported to yield better results [31, 56].
After repair of both concomitant fractures and collateral ligament injuries, if persistent instability of the elbow joint remains, static or dynamic external fixation braces may be applied for fixation. If a hinged external fixation brace is applied, the center of rotation (axis of motion) must be accurately determined by means of the humeral tuberosity and the carriage. Otherwise, the external fixation brace can cause persistent trajectory abnormalities in joint motion. In the management of fresh traumatic instability, a static external fixation brace can be applied, which is relatively easier to operate, and can be considered especially if the operator is inexperienced in the application of a hinged external fixation brace.
Postoperative management
Postoperative management is based on the type of injury, particularly the status of the associated fracture and collateral ligament injury. The elbow joint usually requires braking and elevation of the affected limb for the first postoperative week to eliminate swelling [94], and joint mobility exercises are performed autonomously or under the supervision of a therapist starting at 7-10 days.
If the LCL is repaired and the MCL is intact, active flexion and extension exercises can be performed with the forearm in the rotated anterior position. Flexion of the elbow at 90° is possible with anterior and posterior rotation exercises [95]. It must be emphasized to the patient that functional exercises should avoid shoulder abduction and inversion stress. If both MCL and LCL are injured, the forearm should be placed in neutral position during functional exercises in flexion and extension. In contrast, if the MCL is injured and the LCL is intact or undergoing reliable repair, active flexion and extension exercises should be performed in the rotated posterior position. If a ligamentous injury is present, full extension of the elbow should be avoided. Initially, elbow extension should be limited to a stable position of the elbow joint under anesthesia. The angle of elbow extension is then gradually increased each week, with full extension at 4 weeks and passive joint range of motion exercises starting at 6 weeks; at the 6-week follow-up visit, if the return of range of motion is not satisfactory, a static progressive splint or a loose-tight screw-buckle brace may be applied. Depending on fracture healing, muscle strength training is initiated at 8-12 weeks.
Summary
Radial head fractures are common, and most fractures can be treated non-operatively. It is still controversial whether fractures that are not mechanically blocked during elbow motion have an indication for surgery. Treatment options for radial head fractures include nonoperative treatment, fracture block resection, radial head resection, radial head replacement, and ORIF (Figure 5).