Evaluation and Experience of the Anterior Approach for Coronal Plane Elbow Fractures

Background: The existing approaches to treating elbow fractures include anterior, external, internal, and posterior approaches. Of these, the anterior approach is often not chosen by surgeons to avoid damaging important nerves and blood vessels. In fact, the anterior approach has unique advantages. The purpose of this study was to report the outcomes in 38 patients with coronal plane elbow fractures treated through the anterior approach. Methods: We retrospectively analyzed 38 cases of coronal plane elbow fractures treated through an anterior approach at our institution between March 2015 and July 2019. The length of the surgical incision, operation time, intraoperative blood loss, and postoperative complications were recorded. The range of exion, extension, and rotation of the affected elbow and the healthy elbow were collected at follow-up. Functional outcomes were evaluated using the Mayo Elbow Function Score (MEPS). Results: All 38 patients were followed up. At the nal follow-up, solid osseous union was conrmed for all coronal plane elbow fractures. The mean elbow exion arc was 129.26 ± 6.9 degrees, and the extension arc was 8.87 ± 6.13 degrees. The mean pronation arc was 83.45 ± 2.9 degrees, and the supination arc was 80.05 ± 2.92 degrees. The mean MEPS was 90.0±7.53 points, with 18 excellent cases and 20 good cases. There was no signicant difference in elbow extension, exion, and pronation between 31 cases of single fracture and the healthy elbow (P > 0.05); the arc of supination was slightly worse than that of the healthy elbow (P < 0.05). The VAS pain scores of the patients before the operation, three months after the operation, and during follow-up were compared. The pain of the patients was signicantly reduced after treatment (P < 0.05). Two patients experienced transient postoperative median nerve paralysis, from which they recovered within three months. One patient had mild heterotopic ossication and was not treated because it did not affect the function of the elbow joint. All patients returned to work and were satised with the treatment. Conclusion: The anterior approach has the benets of simplicity, safety, minimal invasion, excellent exposure, and satisfactory prognosis for coronal plane elbow fracture. of this of coronoid was 2.26 times with the B-M interval compared with the B-B interval, allowing visualization for fracture reduction. The above study fully illustrates the theoretical feasibility of using an anterior approach to treat coronal plane elbow fractures.


Background
The elbow joint is composed of the humeroulnar joint, the humeroradial joint, the proximal radioulnar joint, and the surrounding ligaments. It is one of the complex joints of the human body and plays a large role in the functional activities of the upper limbs.
Due to the speci c nature of intra-articular fractures, the treatment of elbow fractures must conform to the criteria of anatomical repositioning, at which point a good surgical eld and rm xation are necessary. The desirable procedure should be performed in a way that minimizes soft tissue stripping without compromising fracture visualization and reduces the risk of elbow stiffness [1], which is closely related to the choice of surgical approach.
At present, the available approaches for the treatment of elbow fractures include anterior, lateral, medial, and posterior approaches [2][3][4]. Of these, lateral, medial, and posterior are more commonly used, and patients with the more complex terrible triad are often treated with a combined approach. In contrast, the anterior approach to the elbow is less frequently chosen by operators due to its anatomical peculiarities, with nerves and vessels intertwined in the operative eld.
In fact, the anterior approach also has unique advantages. It can reduce and x the fracture and repair the anterior joint capsule through direct sight, providing more options for internal xation, and is gradually being promoted in the treatment of coronoid process fractures [5,6].
We found that anterior treatment of elbow fractures is not limited to the coronoid process. Radial head fractures and partial distal humeral fractures that occur in the coronal plane of the elbow, as well as the terrible triad, can be treated well with an anterior approach and even demonstrate unique advantages, which have rarely been reported in the literature. Previously, the outcome of treatment of a single elbow fracture through an anterior approach has usually been described, while a series of fractures in the coronal plane has not been summarized and reported.
The aim of this study was to introduce the treatment of a series of fractures in the coronal plane of the elbow joint by using an anterior approach and to analyze its effectiveness and unique advantages.

Methods
After receiving approval from our Institutional Review Board, we retrospectively analyzed 38 consecutive patients (25 males, 13 females; mean age, 32.8 years; range, 14-69 years) who had undergone open reduction and internal xation through an anterior approach in our hospital for the treatment of coronal plane elbow fractures between March 2015 and July 2019 (Table 1). The mechanism of injury included 26 cases of falling on at ground while walking, 8 cases of falling from a height, 3 cases of tra c accident, and 1 case of heavy object impact. There were 7 cases of coronoid process with radial head fracture. These patients received initial reduction therapy in the emergency room.
All patients had closed injuries without any neurovascular complications. All 38 elbows were treated surgically at a mean of 4.3 days (range, 2-12 days) after the initial injury. The speci c indications for surgical intervention include displaced intra-articular fractures and instability of the elbow within a functional arc of motion after closed reduction.
Preoperative radiological examinations were routinely performed to determine the exact location of fractures located in the coronal plane. CT and 3D reconstruction were used to obtain additional information on fracture comminution and displacement that was not apparent on X-rays.

Surgical technique
All patients were treated with nerve block anesthesia, and the elbow joint was abducted in the supine position.
Routine disinfection was extended to the area above the shoulder joint to avoid restriction of the operative area caused by a tourniquet. A tourniquet was applied to the proximal 1/3 of the upper arm after elevating the affected limb for 3-5 min, taking care to avoid excessive blood expulsion and appropriate retention of blood in the arteriovenous system of the forearm to help identify intraoperative anatomy. Approximately 5 cm above the elbow crease, an "S" incision was made from the medial or lateral border of the biceps muscle to the midline of the forearm, avoiding a 90° angle with the elbow crease and preserving intact soft tissue structures as much as possible.
When two or more fractures were involved, the skin incision was appropriately extended, and the subcutaneous tissue was bluntly separated after skin incision, identifying and protecting the medial cutaneous nerve of the forearm (identifying the lateral cutaneous nerve of the forearm when a lateral incision is used), basilic vein, cephalic vein, and median cubital vein.
(1) To manage a coronoid fracture, the bicipital aponeurosis was lifted with a vascular clamp and then incised. The biceps muscle was pulled laterally, and the pronator teres muscle was pulled medially, with the brachial artery and median nerve in its deeper layers and the median nerve medial to the brachial artery. At this point, the elbow joint was slightly exed by 5° to 10° to keep the vascular nerve bundle in a tension-free state, and the brachial muscle was exposed in the interval between the brachial artery and the median nerve. The brachial muscle was incised along the course of the muscle bers to expose the joint capsule.
(2) In the management of radial head fractures, the biceps brachii muscle was rst pulled medially (Fig. 4d). The forearm was xed in a state of extreme supination, the supinator muscle was cut at the insertion point where the supinator muscle attaches to the radius while avoiding the Frohse arch, and nally, the joint capsule was opened to expose the radial head.
(3) Both of these intervals were used to expose the distal humerus by extending proximally, but a closer interval was selected depending on the type of distal humeral fracture.
After the joint capsule was opened and the elbow joint was fully extended, most fracture fragments usually reset themselves at this point. A 1.5 mm Kirschner wire was typically used to temporarily x the fragment in the anteroposterior direction and maintain pressure on the fragment. After uoroscopy determined that the fracture fragments were satisfactorily repositioned, the appropriate internal xation device was selected according to the different fracture types and xed after shaping the fracture according to its morphology.
In patients with elbow dislocation, the elbow was examined for stability after reduction, and a concentric reduction should be achieved, with an arc of exion-extension from 20° to 130° and no posterior or posterolateral subluxation or dislocation. Those who could not maintain stability required ligament repair or reconstruction, and if necessary, a combined approach was used. The tourniquet was released before closure, and meticulous hemostasis was performed. Drainage was placed, and the incision was sutured and dressed.

Postoperative Management
Patients could choose to supplement their postoperative xation with a hinged plastic brace. The forearm was positioned in a pronation or supination position in cases of lateral or medial collateral ligament de ciency, respectively. The forearm was splinted in neutral rotation if both the medial and lateral collateral ligaments had been repaired. A light diet was taken 2 hours after the surgery, and cefuroxime sodium (3.0 g) was given intravenously on the same day to prevent infection.
The patients were given intravenous cimetidine, and the affected limbs could be elevated to reduce swelling to prevent stress after gastrointestinal anesthesia. Analgesic treatment was actively administered according to the VAS score, and single or combined analgesic drugs were used depending on the patient's condition, which facilitated rest and recovery and thus promoted healing to effectively reduce the length of hospitalization and the patient's medical expenses. Positive and lateral elbow lms were reviewed the day after surgery. The medication was changed regularly, and drainage was usually removed within three days postoperatively. On the second postoperative day, passive exion and extension exercises of the elbow were started. Active movement of the wrist and metacarpophalangeal joints can help determine whether the nerve is injured during surgery. Elbow exion and extension and rotation exercises were gradually performed starting one week after surgery. Active exion and extension exercises began in the second week. Unrestricted exion and extension and strength exercises were performed in the 8th week. In addition, to prevent heterotopic ossi cation, patients were recommended to take oral nonsteroidal anti-in ammatory drugs such as indomethacin for six weeks, and those with severe gastrointestinal reactions could switch to etoricoxib tablets.

Data collection and analysis
At follow-up, clinical and radiological examinations were performed by a clinical investigator who was not involved in the treatment. The clinical evaluation included the patient's bilateral arc of motion in elbow exion, extension, pronation, supination, the Mayo Elbow Performance Score (MEPS) [7], and examination of detectable surgical complications. Plain lms were evaluated for fracture union, implant loosening, heterotopic ossi cation, degenerative changes, and joint congruency. Intraoperative and postoperative complications were also recorded. A con rmed fracture union was de ned as when the fracture showed evidence of external bridging of the callus across the fracture line in the three cortices on the lateral view of the elbow. Statistical analysis was performed using SPSS version 26.0 software (SPSS Inc., Chicago, IL).

Results
All coronal plane fractures were successfully treated with internal xation of the fracture using an anterior approach, and nal follow-up X-rays showed solid osseous union. The average time to radiologic union was 14.4 weeks (range, 12-18 weeks).
The outcomes are shown in Table 2. The mean duration of follow-up was 21.26 months (range, 12-36 months). At the nal follow-up, the mean elbow exion arc was 129.26 ± 6.9 degrees, and the extension arc was 8.87 ± 6.13 degrees. The mean pronation arc was 83.45 ± 2.9 degrees, and the supination arc was 80.05 ± 2.92 degrees. The mean MEPS was 90.0 ± 7.53 points, with 18 excellent cases and 20 good cases. There was no signi cant difference in elbow extension, exion, and pronation between 31 cases of a single fracture and the healthy side (P > 0.05); the arc of supination was slightly worse than that of the healthy side (P < 0.05) ( Table 3; Fig. 1). The VAS pain scores of the patients before the operation, three months after the operation, and during follow-up were compared (Fig. 2). The pain of the patients was signi cantly reduced after treatment (P < 0.05) ( Table 4).  There were no intraoperative complications. There were also no wound complications or implantation failures. Two patients experienced transient postoperative median nerve paralysis, the symptoms disappeared after regular oral administration of nutritional nerve drugs, and the symptoms did not recur in subsequent follow-up. Two patients experienced transient postoperative median nerve paralysis, the symptoms disappeared after regular oral administration of nutritional nerve drugs, and the symptoms did not recur in subsequent follow-up. One patient had mild heterotopic ossi cation and was not treated because it did not affect the function of the elbow joint. All patients returned to work and were satis ed with the treatment (Fig. 3 ~ 6).

Discussion
The anterior approach has been widely used in upper limb surgery. It is considered a valuable option in the treatment of proximal radius fractures, reconstruction of the distal biceps tendon, resection of anterior elbow tumor, and soft tissue infection [8]. According to the mechanism of injury, after the occurrence of elbow fractures, the bone fragments often dislocate to the coronal plane. However, due to the anatomical characteristics of the anterior elbow joint, surgeons often avoid the anterior approach due to fear of damage to the neurovasculature and often choose the lateral approach, which makes it di cult to look directly at and address the fracture surface [9,10]. With the gradual understanding of the anatomical relationship of the elbow joint by clinicians and the development of microsurgical techniques, the anterior approach is increasingly used in the treatment of elbow fractures.
Elbow joint fracture is an intra-articular fracture, and anatomical reduction of the articular surface is the key factor to achieving strong xation and a satisfactory elbow joint [11,12]. Adequate exposure of the articular surface is a prerequisite for anatomical reduction of fractures. Some scholars [13] compared the exposure area of the distal humerus articular surface by different surgical approaches and found that the average percentages of exposed articular surfaces by anterior and posterior olecranon osteotomy and medial and lateral approaches were 45.7% ± 2.0%, 53.9% ± 7.1%, 20.6% ± 4.9% and 28.5% ± 6.3%, respectively. We concluded that the anterior and posterior approaches are more adequate than the medial and lateral approaches for intraoperative articular surface exposure in the treatment of distal humerus fractures. Yang et al. [14] compared the exposure area of the coronoid process fracture between the biceps tendon-brachial artery interval (B-B interval) and brachial artery-median nerve interval (B-M interval) from an anterior approach, and the results of this study showed that the average exposed surface area of coronoid process was 2.26 times greater with the B-M interval compared with the B-B interval, allowing visualization for fracture reduction. The above study fully illustrates the theoretical feasibility of using an anterior approach to treat coronal plane elbow fractures.
Compared with other approaches, the anterior approach has some advantages [1,6,14]: (1) providing excellent visualization of and the most direct access for fractures in the coronal plane (Fig. 3c); (2) allowing anatomic reduction of the fracture and more xation options, as anterior to posterior compression is more mechanically appropriate, which reduces the risk of fracture xation failure (Fig. 3b); (3) avoiding a large amount of soft tissue dissection; (4) avoiding damaging the exor-pronator muscle mass and the ulnar nerve; and (5) exploring the ulnar collateral ligament of the elbow joint and repairing the anterior joint capsule, which is bene cial to the stability of the elbow joint and reduces the occurrence of heterotopic ossi cation.
Our point of view is that it is not appropriate to directly choose the surgical approach without considering the type of fracture. One of the rules of classifying fractures is to better understand the mechanism of injury and local anatomical characteristics and then provide guidance for treatment. Scienti c surgical protocols should not be limited to absolutely identical patterns, and the surgical approach should be individualized according to the patient's injury.
Since most elbow joint coronoid fractures are displaced forward, as long as the elbow joint is unstable, anterior surgery can be considered [15,16]. The Kocher approach is commonly used in the treatment of the radial head [17], which is accessed from the extensor carpi ulnaris and the anconeus interval. It is primarily indicated for the repair of radial head fractures and lateral collateral ligaments, but there are a certain number of patients who have a combined coronoid fracture along with the presence of a radial head fracture [18]. In such cases, the use of the lateral access route is obscured by the radial head, which makes the operating space narrow. There are even doctors who treat coronoid fractures after osteotomy of the radial head. This method causes damage to the stability of the elbow joint and additional trauma, which is di cult for patients to accept. The radius itself has intraoperative rotatable properties, so even radial head fractures that occur laterally in the sagittal plane can fully expose the fracture surface when using the anterior approach.
The posterior approach provides the greatest exposure of the distal humeral articular surface for surgery for distal humerus fractures. However, nonunion in 30% of patients is a common complication of this approach [19,20], along with a larger surgical incision and prolonged operation time. Due to the presence of an anatomical structure in the distal humerus that is tilted approximately 30° anteriorly, the advantage of the anterior approach allows internal xation under direct vision [13]. Therefore, the anterior approach is recommended for AO type B fractures that mainly occur on the coronal plane, including the capitulum, trochlea, or combined fractures.
The terrible triad of the elbow is an incapacitating injury entailing posterior dislocation and fractures of the radial head and coronoid and is also often associated with a collateral ligament injury. Traditional treatment is usually a combined medial-lateral approach. However, it is worth considering that the occurrence of the terrible triad is posterior dislocation of the elbow joint caused by violence, along with forced anterior displacement of the radial head and coronoid process by the distal humerus. In terms of the injury mechanism, "smooth" reduction under direct vision by the anterior approach will bring advantages that other approaches cannot achieve. Some of the cases included in this study involved the terrible triad, and all were treated by the anterior approach with good results (Fig. 6).
Concerning complications, the serious neurovascular injury that many scholars worry about did not occur. Only two patients experienced transient postoperative median nerve paralysis, and the symptoms disappeared after regular oral administration of nutritional nerve drugs and did not recur in subsequent follow-up. There was only one case of mild heterotopic ossi cation in the front of the elbow joint, which was not found to bring subjective symptoms to the patient or affect the movement of the elbow joint during the follow-up process, so it was not treated. Some scholars [21] worry that injuring the brachialis will increase the incidence of heterotopic ossi cation. To reduce the occurrence of heterotopic ossi cation, one may choose not to cut the brachialis longitudinally and choose to expose the fracture end after distraction at its edge. Since there was no additional osteotomy, as in the posterior approach, we did not observe the occurrence of nonunion. The most common symptoms were pain and limitation of motion.
For patients with signi cant pain, timely drug analgesic treatment was administered, and signi cant relief was obtained within a period after surgery. A considerable number of patients with postoperative limitation of motion experience fear, and it is effective to provide active rehabilitation guidance to such patients after surgery.
Based on the study results and long-term clinical practice, we summarized some noteworthy points regarding the anterior approach for the treatment of fractures of the elbow in the coronal plane: (1) Intraoperative elbow exion of 5° to 10° is bene cial to reduce muscle tension while allowing the sliding of vascular nerves between loose tissues and reducing the risk of vascular nerve injury.
(2) Since the deep fascia below the external epicondyle of the humerus penetrates the lateral antebrachial cutaneous nerve, the lateral side of the incision should be within 1.5 cm of the outer edge of the biceps tendon. It may be necessary to cross the cubital crease. In that case, the surgical incision should be selected in the position above the cubital crease to prevent the possibility of postoperative scar contracture affecting elbow joint activity, as the lateral antebrachial cutaneous nerve in this area is located in the deep layer and is not easily injured during surgery.
(3) When the biceps aponeurosis needs to be cut, it can be picked up with a vascular clamp and propped open, and then a scalpel can be used to reverse the cutting to avoid damage to the brachial artery and vein and median nerve below. In addition, the traction of the nerve should be gentle.
(4) In the treatment of coronoid fractures, interval access between the brachial artery and the median nerve is chosen for the anterior approach, whereas interval access between the median nerve and the pronator interval is high risk because of the nerve branches here. The advantages of this approach are that it is safer to enter from the vascular-neural interval; it directly exposes the fracture site and facilitates reduction; it also facilitates xation with a plate and causes less tissue damage; the disadvantage is that the medial coronoid process cannot be xed.
(5) Care needs to be taken when exposing the radial head, over which a deep branch of the radial nerve migrates across the Frohse arch as the posterior interosseous nerve. To avoid injury to the radial nerve, the radius needs to be rotated extremely posteriorly, the termination point of the posterior rotator muscle needs to be separated, and the joint capsule is pushed from the inside out with an osteotome. Simultaneously, using the characteristics of the radius, the radial head fracture area was rotated to the surgical eld for exposure.
(6) Intraoperative placement of drainage is essential, and adequate drainage prevents hematoma formation and reduces the risk of infection and heterotopic ossi cation.
(7) Early rehabilitation activities are recommended for patients. One of the details here is that the elbow joint should not be bandaged too much, as a thick sterile dressing will greatly affect the arc of elbow bending.
(8) To prevent heterotopic ossi cation after surgery, it is recommended that patients take oral nonsteroidal antiin ammatory drugs such as indomethacin for six weeks; those with severe gastrointestinal reactions can take etoricoxib instead.
There were a few shortcomings in this study. The study was essentially retrospective, and there was no control group for comparison. Furthermore, the sample size of the different fracture types included in the study was smaller.
Future work may also explore the e cacy of the anterior approach in the treatment of the terrible triad based on prospective studies with expanded sample sizes.

Conclusion
The anterior approach for the treatment of coronal plane elbow fractures, especially combined fractures, has a clear surgical eld, large operation space, easy reduction, more xation options, less trauma, fewer complications, and good postoperative function recovery. Moreover, in the case of adequate visualization of the surgical eld, clearly separated and protected vessels and nerves always warn the surgeon and make them less vulnerable. In conclusion, the anterior approach is reliable in the management of coronal plane elbow fractures and deserves to be used in clinical practice. Figure 1 Comparing the mobility of the affected and healthy elbow joints after surgery.

Figure 2
The VAS scores of patients before surgery, at three months after surgery, and at the nal follow-up were compared.

Figure 3
A 40-year-old man presented with a Regan and Morrey type II coronoid process fracture. Preoperative radiographs (a). Intraoperative exposure of the coronoid process through the anterior elbow approach (c). Solid union and good outcomes were achieved at the 8-month follow-up (b, d).

Figure 4
A 23-year-old man presented with a type of mason: II radial head fracture. Preoperative X-ray (a) and computed tomography (b). Intraoperatively, the biceps brachii was exposed and pulled medially to enter between the brachioradialis and biceps brachii interval (d1). The supinator muscle was located in its deeper layers (d2). Solid union and good outcomes were achieved at the 1-year follow-up (c, f).