Treatment for Complex Elbow Fractures Involving Both a Hinged External Fixator and Internal Fixation

Purpose To explore the clinical outcomes of a hinged external xator combined with internal xation in treating complex elbow fractures. Methods This was a retrospective analysis of 42 cases of complex elbow fractures treated in our hospital from January 2015 to December 2019. Twenty-four cases were treated with a hinged external xator combined with internal xation (external xation group), including 14 cases of the terrible triad of the elbow, 5 cases of posterior Monteggia fracture, and 5 cases of transolecranon fracture-dislocation. Eighteen cases were treated with adjustable brace xation combined with internal xation (brace group), including 11 cases of the terrible triad of the elbow, 3 cases of posterior Monteggia fracture and 4 cases of transolecranon fracture-dislocation. All patients were treated with open reduction and internal xation, and the patients with postoperative elbow instability underwent xation with a hinged external xator or adjustable brace. Preoperative and surgical data were collected. At the last follow-up, elbow motion (extension-exion, rotation) was recorded in the two groups of patients, and the Mayo Elbow Function Score (MEPS) was used to assess elbow joint function.

Most complex elbow fractures are high-energy injuries, have complex injury mechanisms, are di cult to treat, have poor prognoses, and are associated with sequelae. Complex elbow joint fractures involve not only complex fracture types but also multiple fractures, including proximal ulna, radial head, coronal process and distal humerus fractures, and radial head and coronal process fractures are the most common. Moreover, the soft tissue around the joint is accompanied by severe contusion, and the ligament structure is severely damaged, which leads to the loss of bone and soft tissue stability in the elbow joint dislocation [1][2][3][4][5]. Nonoperative treatments for complex elbow fractures rarely yield satisfactory clinical results, and the incidence of related complications, including elbow instability, heterotopic ossi cation, joint stiffness and traumatic arthritis, is high, leading to a large burden on the life of patients. At present, most scholars believe that [6-8] complex elbow fractures need to be treated surgically to restore bone and soft tissue stability in the elbow joint and that functional elbow exercises should be performed as soon as possible after surgery. However, the goal of maintaining the stability of the elbow joint contradicts early functional exercise. Some studies [9] have shown that after an elbow stiffness release operation, the use of a hinged external xator can allow early functional exercise by maintaining the stability of the elbow joint and can yield good medium-and long-term results. However, in most cases, complex elbow joint xation is performed with a single xation method, either simple internal xation or simple external xation. Some studies [10][11][12] have used hinged external xators to treat patients with acute or chronic elbow instability and achieved good results. In clinical practice, patients with complex elbow fractures are still unstable after open reduction and internal xation and are treated with a hinged external xator or adjustable brace. Through a retrospective analysis of these cases, we (2) multiple fractures of the same upper limb; (3) fractures in both upper limbs or those accompanied by nerve injury; and (4) severe medical diseases before surgery precluding surgical treatment. A total of 81 cases treated within the past 5 years were included, and 39 cases were excluded after screening. There were 14 cases of open fracture, 7 cases of multiple fractures in the same upper limb, 4 cases of fractures in both upper limbs, 4 cases of nerve injury, and 10 cases that were followed up for less than 12 months. Finally, 42 patients were included in this study (Fig 1). Twenty-four patients were treated with a hinged external xator (external xation group). These patients' ages ranged from 20-60 years (average 41.5±10.6 years), and there were 18 males and 6 females. There were 14 cases of the terrible triad of the elbow, 5 cases of posterior Monteggia fracture, and 5 cases of transolecranon fracture-dislocation; 15 cases involved the dominant side, including 8 cases of fall-related injuries, 14 cases of tra c-related injuries and 2 cases of sports-related injuries. The time from injury to the operation was 3-12 days (average 5.4±2.4 days). There were 18 patients treated with adjustable brace xation (brace group). These patients' ages ranged from 20-60 years (average 41.2 ±9.8 years), and there were 13 males and 5 females. There were 11 cases of the terrible triad of the elbow, 3 cases of posterior Monteggia fracture, and 4 cases of transolecranon fracture-dislocation; 12 cases involved the dominant side, including 5 cases of fall-related injuries, 12 cases of tra c-related injuries and 1 case of a sportsrelated injury. The time from injury to the operation was 3-12 days (average 5.6±2.3 days) ( Table 1). This study all methods were carried out in accordance with guidelines and regulations. This study was approved by the ethics committee of HongHui Hospital, Xi'an Jiaotong University, and all patients provided informed consent prior to participating. Typical case images have been allowed by participant to be displayed in the manuscript.

Surgical methods
All patients were treated with general anesthesia and placed in a supine position or lateral supine position, depending on the fracture type; an air bag tourniquet was placed at the root of the upper arm, The surgical site is routinely disinfected and covered with aseptic towels. The surgical methods presented by Pugh [13] and McKee [14] for the treatment of complex elbow fractures were used. The surgical approach used was the combined medial and lateral elbow approach or posterior median approach [15][16][17]. For the treatment of the fractures, the radial head fractures were xed with countersunk nails or miniature plates. If severe comminution could not be repaired, arti cial radial head replacement was performed. The olecranon fractures were xed with a plate and screw or both a Kirschner wire and tension band. Coronal process fractures were xed with lag screws, miniature plates or loop plates.
Moreover, the articular capsule and medial and ligament were explored, in accordance with the injury mechanism and joint dislocation, and the structures of the articular capsule and ligament were sutured and repaired with thread anchors. After the completion of the above operation, omnidirectional passive movement of the elbow joint ( exion and extension, pronation, supination) was carried out to con rm the stability of the elbow joint, and the elbow joint was xed with an external xator or adjustable brace if there was still instability.

Installation of external xture
The shoulder was abducted, and the forearm was placed on the operating table in a pronated position to determine the center of rotation. Standard positive and lateral lms of the distal humerus were taken by a C-arm X-ray machine to determine the needle entry point. The lateral lm focused on the center of the head of the humerus and the concentric circle of the pulley. A Kirschner needle with a diameter of 2.0 mm was slowly inserted from the outside to the inside from this point. The standard X-ray lm of the front and side of the elbow joint was taken again to ensure it was located in the rotation center of the elbow joint. The two movable arms of the external xator were xed on the lateral humerus and the ulnar crest with semithreaded nails. A small incision was made in the corresponding part of the skin, blunt separation was performed directly to the bone surface, and the nerves and other important tissues were protected. After drilling, two half-threaded needles were manually implanted at the distal and proximal ends. It was con rmed by X-ray that the tip of the needle passed through the medial cortex. The force line of the elbow joint was adjusted, the range of motion of the elbow joint was measured, the elbow was exed to 90 °, the distance between the joints was maintained at 2 mm, and nally, the humerus end and the ulnar end of the external xator were connected. Then, the bleeding was thoroughly stopped, the incision was rinsed with normal saline, a drainage tube was placed, the incision was sutured layer by layer, and the wound was wrapped with aseptic dressing.

Postoperative treatment
Antibiotics were routinely used to prevent infection within 24 hours after the operation. Metacarpophalangeal joint and interphalangeal joint movement was performed as soon as possible after the operation, as this movement can promote distal blood circulation and actively eliminate swelling. If the drainage volume was less than 30 ml within 24 hours after the operation, the drainage tube was removed. It was recommended that all patients take indomethacin enteric-coated tablets (25 mg, 3 times a day) for 4 weeks to prevent heterotopic ossi cation. Under the guidance of a professional rehabilitation physician, the brace group began functional exercises 3 days after the operation under the protection of the brace; the elbow joint was xed at different exion angles (30°, 90°, 130°) for 30 minutes each time, three times a day, and xed in a straight position at night. The external xator group began functional exercises 3 days after the operation. The elbow was xed in a straight position at night, and the lock was released during the day so that passive exion and extension exercises could be performed for a continuous 30 min period 3 times a day. When the edema of the elbow joint was alleviated, the frequency of exercise was increased appropriately, and the adjustable brace and external xator were removed 6 ~ 8 weeks after the operation.

Evaluation project
Three days after the operation, the anterior and lateral X-ray lms of the elbow joint and plain CT scan and three-dimensional reconstruction were reexamined to evaluate the repair of the fracture. The positive and lateral X-ray lms of the affected limbs were reexamined at 1, 2, 3, 6 and 12 months after the operation to evaluate the extent of fracture healing. The count data are expressed as numbers (n), and the comparisons between the two groups were performed by the χ2-test; the measurement data are presented as M ±SD, and the comparisons between the two groups were performed by the t-test. P values < 0.05 were considered statistically signi cant.

General results
The basic characteristics of the two groups of patients are shown in Table 1, and there were no signi cant differences in demographics between the two groups (P>0.05, Table 1). The surgical data of the two groups of patients are shown in Table 2. The average operation time and the average number of intraoperative uoroscopies performed in the external xation group were much higher than those in the brace group, and the difference between the two groups was statistically signi cant (P=0.003, P=0.000, Table 2). The average hospitalization cost in the brace group was much lower than that in the external xator group, and the difference was statistically signi cant (P=0.000, Table 2).

Follow-up results
All patients were followed up for 12-55 months (mean 28.2 months). All patients exhibited bony healing, and no deep tissue infections or nerve injuries occurred. The fracture healing time in the external xator group was slightly longer than that in the brace group. The difference between the two groups was not statistically signi cant (P>0.05, Table 2). At the last follow-up, the average exion-extension range of the elbow and the average rotation range of the forearm in the external xator group were much better than those in the brace group, and the difference was statistically signi cant (P=0.034, P=0.039, Table 3). In the external xator group, the average MEPS score was 89.8±11.3, and in the brace group, the score was 81.1±15.5. The difference was statistically signi cant (P=0.042, Table 3). The curative effect in the external xator group was excellent in 14 cases, good in 7 cases, fair in 2 cases and poor in 1 case. The excellent and good rate was 87.5%. In addition, the curative effect in brace group was excellent in 8 cases, good in 5 cases, fair in 2 cases and poor in 3 cases. The excellent and good rate was 72.2% ( Fig  2). The typical case is shown in gure 4.

Complications
Redness and swelling of the skin around the pinhole and non-purulent exudate occurred in 3 cases (12.5%) in the external xation group, and redness and swelling around the incision occurred in 1 case (5.6%) in the brace group. The cases in both groups were cured by oral antibiotics. Heterotopic ossi cation of the elbow joint occurred 3-6 months after the operation in 5 cases (20.8%) in the external xation group and 3 cases (16.7%) in the brace group. All 8 cases were mild heterotopic ossi cation cases (Brooker1-2) [19] that did not require special treatment. According to Morrey et al. [20], an elbow joint functional range of motion ( exion, extension or rotation) less than 100° indicates elbow joint stiffness, and there was 1 case (4.2%) in the external xation group and 3 cases (16.7%) in the brace group (Fig 3). The elbow joint release operation was performed 6 months after the operation in all patients except 1 patient with severe stiffness in the brace group, who was treated conservatively.

Elbow joint injury characteristics
The elbow joint is a compound joint that includes the humerus-ulnar joint, humeral-radial joint and upper ulnar-radial joint. It is the most exible joint in the upper limb. The integrity of the bone and ligament is very important for the stability of the elbow joint. The repair of the coronal process, medial and lateral collateral ligament and olecranon notch of the ulna will directly affect the functional recovery of the elbow joint. Complex elbow joint fractures are high-energy injuries. When injured, the bony structure, periarticular ligaments and joint capsules that maintain the stability of the elbow joint are damaged. When the elbow joint is severely injured, complications such as heterotopic ossi cation and stiffness of the elbow joint are prone to occur, which affects the functional recovery of the elbow joint after surgery and signi cantly reduces the patient's quality of life.

Treatment of complex elbow fractures
For the treatment of complex elbow fractures, because they are often accompanied by multiple structural injuries of the elbow joint, X-ray and CT scans and three-dimensional reconstruction must be performed before the operation to con rm the diagnosis, formulate the best treatment plan, and restore bone and soft tissue stability as much as possible during the operation. After the anatomical state of the elbow joint is restored and rigid internal xation is applied during the operation, fracture redisplacement and elbow dislocation may still occur when there is instability. Some scholars have observed a better range of motion and curative effect in the elbow joint when a hinged external xator was used. We used a hinged external xator to maintain the stability of the elbow joint. In this study, 24 cases of complex elbow fractures were treated with internal xation combined with a hinged external xator. At the last follow-up, the excellent and good rate of elbow function evaluation was 87.5%, and the curative effect was considerable. The analysis shows that the hinged external xator can not only help to maintain the concentric movement of the humeral ulnar joint but also maintain the stability of bone and soft tissue, allowing functional exercises to be performed early. In addition, early elbow rehabilitation training can prevent muscle atrophy, reduce joint adhesion and improve the curative effect. However, it should be done step by step and carefully to avoid internal xation loosening and failure.

Application and characteristics of external xator
External xators have been used for more than 180 years, and they were rst used to treat lower limb injuries. At present, they have been widely used to treat limb fractures [21][22], but they are rarely used in combination with internal xation in the treatment of complex elbow joint fractures. For elbow joint instability, Rao AJ et al [23] treated 20 patients with chronic elbow instability with a static external xator. Although the stability of the elbow joint was restored, the secondary operation rate was 40%, and 25% of these operations were performed due to elbow stiffness. The reason for elbow stiffness may be that the elbow joint is xed for a long time, which is contrary to the theory that early exercise should be performed after complex elbow joint operations, so a static external xator is not suitable for the treatment of postoperative joint instability in complex elbow fractures. After performing a release procedure for severe traumatic elbow stiffness, Sun et al [24] used a hinged external xator to not only provide stability for the elbow joint but also meet the requirements of early exercise, and the therapeutic effect was considerable. Most scholars believe that an important goal of the treatment of complex elbow fractures is to restore the absolute stability of the elbow joint as much as possible through surgery and start functional exercises as early as possible. However, complex elbow fractures involve a wide range of injuries and severe structural damage. Even if the tissue around the elbow joint is repaired, there is instability during functional exercise. In the past, plaster xation was often used after operations, and with this method, the best time for functional exercise was missed. Biomechanical studies have shown that [25] a metal hinged external xator can modify the joint space, effectively eliminate excessive friction on the joint surface, help protect the joint surface, and prevent reinjury of the bone and soft tissue after reduction. Volkov et al [26] found that the use of an external xator after elbow joint operations can effectively preserve the height of the humerus-ulnar and humeral-radial joints, eliminate the axial pressure and shear force of the elbow joint, and effectively prevent displacement of the radial head and coronal process fractures. To date, a metal hinged external xator has been used in the treatment of the terrible triad of the elbow, complex fractures and dislocation of the elbow joint, stiffness release procedures for the elbow joint and so on. It has shown its uniqueness. Iordens et al [27] treated 26 patients with complex elbow dislocation with a hinged external xator, and satisfactory range of motion and functional results for the elbow joint were observed at the one-year follow-up. However, the requirements for the use of an external xator are relatively strict, and there is a certain degree of technical di culty. The goal of the method is to determine, restore and maintain the rotation center of the elbow joint, and these processes are considered di cult; the external xator must be consistent with the rotation center of the elbow joint. Forthman et al [28] reported that if the external xator is not applied properly, it will often have the opposite effect. A deviation of the rotation center of 5° will increase the motion resistance by 3.7 times, and a deviation of 10° can increase the motion resistance by as many as 7.1 times, thereby increasing the probability of the semithreaded needle loosening and breaking. In a study [29] of complications of hinged external xators of the elbow joint, it was pointed out that the common complications were infection (including super cial and deep infection), loosening of the xator, heterotopic ossi cation and so on. Some scholars have reported that [27,30] during functional exercise, fracture of the steel pin of the external xator and malunion of the fracture can occur. In this study, there were 3 cases of infection in the external xation stent group, all of which were super cial infections. There were 5 patients had mild heterotopic ossi cation, and there were no xed steel needle fractures or fracture malunion cases. The excellent and good rate of elbow function at the last follow-up was 87.5%. We also found that the cost of the external xator is high, which adds a certain economic burden on the patients. Second, to avoid the occurrence of infection, it is necessary to disinfect the xed needle regularly, which increases the number of daily nursing tasks. The elbow joint is an upper limb joint with a large range of motion and very complex kinematic mechanics, and functional recovery is very important for patients. Compared with the nal good function of the elbow joint, we think that the above shortcomings are acceptable. The limitation of this study is that the study is a retrospective study, and the quality of the records was not necessarily the same because different medical staff members recorded the case data, which may affect the scienti c reliability of the analysis results. Therefore, more prospective clinical trials are needed to verify these results. Second, the number of cases involved in the study was small, and the follow-up time was short, so it is necessary to assess more cases and include longer follow-up periods to ensure the accuracy of the results of the study.
In summary, for patients with joint instability after undergoing internal xation of a complex elbow fracture, a metal-hinged external xator can increase the elbow gap, restore the maximum controllable range of motion, effectively maintain the stability of the elbow, prevent the internal xation failure, promote the recovery of elbow function and improve patient satisfaction with the clinical treatment.

Abbreviations
Mayo elbow performance score, (MEPS) Declarations Con ict of interest statement No con ict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for published elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed.

Ethics approval and consent to participate
This study all methods were carried out in accordance with guidelines and regulations. This study was approved by the ethics committee of HongHui Hospital, Xi'an Jiaotong University, and all patients provided informed consent prior to participating.

Consent for publication
Not applicable Availability of data and materials All data generated or analyzed during this study are included in this published article.

Competing interests
No con ict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for published elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed.    The typical case is a 42-year-old male who fell from a height and caused posterior Monteggia fracture of the right elbow joint (Jupiter A ). a and b Preoperative anteroposterior and lateral view, c Preoperative 3D