Can Only Fix Sternoclavicular Joint to Treat Bipolar Clavicle Injury?

Background: Owing to the rarity of bipolar clavicle injury, treatment remains controversial. The purpose of this study is to report treatment of bipolar clavicle injury with internal plate xation. Methods: We present our experience of clavicle hook plating for sternoclavicular joint dislocation and anatomical plating for distal clavicle fracture for the treatment of three consecutive bipolar clavicle injuries with different injury patterns. At follow up, radiographs were assessed for joint congruity, fracture union, and implant failure. Clinical evaluation included Disability of the Arm, Shoulder, and Hand (DASH), Constant and Murley Score, Visual Analog Scale (VAS), and complications. Results (cid:0) All patients had a minimum follow-up of six months. Each fracture had solid union, and each dislocation showed no sign of recurrent dislocation, the mean shoulder forward exion was 153.3°±10.4°, the mean DASH score was 13.9±9.2 points. The mean Constant and Murley score was 82.3±12.3 points, and, the mean VAS score was 2.2±2.0 point. No complications were encountered, and each patient was highly satised with their treatments. Conclusion: Our experience of using internal plating for bipolar clavicle injury is positive, as it allows early mobilization and resulted in good joint function. Also, only sternoclavicular joint xation might be sucient for some part of bipolar clavicle injury, acromioclavicular joint xation is not necessary unless residual instability existence. for the nal evaluation. At the each fracture had solid union, and each dislocation showed no sign of recurrent instability, the mean shoulder forward exion was 153.3°±10.4°, the mean DASH score was 13.9±9.2 points. The mean Constant and Murley joint function score was 82.3±12.3 points, with 1 excellent cases and 2 good cases. And, the mean VAS score was 2.2±2.0 point. patient 1 and patient 3 had mild shoulder limitation, each patient was able to resume preinjury daily activity and satised with their treatments.


Background
Although acromioclavicular (AC) joint dislocations and distal clavicle fractures are common, sternoclavicular (SC) joint injury and fractures of the medial clavicle are rare. In 1831, Porral [1] rstly reported a case with simultaneous dislocation or subluxation of both ends of the clavicle, Beckman [2] reported a 16th case in 1924, and it was not until 1982 that more cases were reported [3], this injury is also named as " oating clavicle". Nowadays, the term bipolar clavicle injury or oating clavicle is often referred to any combinations of dislocation and fracture at both ends of the clavicle [4].
Bipolar injury of the clavicle is rare and often caused by high-energy trauma, although road-tra c and sports injuries have increased the frequency of clavicle injury, most reports have been based on single cases, only a few of published English studies presented multiple cases [4][5][6][7][8]. Thus, treatment of this injury remains limited. Both surgical and conservative treatment strategy had been successful reported by different researchers, however, this is no consensus in literature regarding the best management for bipolar clavicle injury. The purpose of this study is to report three cases with different injury patterns who were successful treated by a clavicle hook plate (Balser plate) xation, to explore the advantages and disadvantages of the technique and to review recently published literature.

Subjects
After obtaining Institutional Board Review approval, the authors retrospectively analyzed patients with bipolar clavicle injury seen from December 2017 to March 2020 in Hong Hui Hospital, Xi'an Jiaotong University School of Medicine (Xi'an, China). This study was approved by the Ethics Committee of Hong Hui Hospital, and each patient agreed to publish their images and individual clinical details with written informed consent. During this period, the authors treated 4 patients with bipolar injury of the clavicle. The surgical indications were dislocations or fractures that could not be reduced by conservative treatment and/or appeared prone to recurrence after conservative treatment. Among these patients, one patient with both AC and SC joint dislocation was treated conservatively, and the remain three cases underwent internal clavicle hook plate xation. Thus, the three cases with surgical treatment met the following inclusions: bipolar clavicle injuries were treated by clavicle hook plate xation with a ≥6-month follow-up (Table 1). Patients with bipolar clavicle injuries treated by conservative treatment or patients with only one single clavicle end injury were excluded from this study.

Surgical technique
After administration general anesthesia, the patient was placed in a semi-sitting beach chair position on the operating table. An oblique incision was made over the medial clavicle and sternum. After soft tissue aps were retracted, the displacement of medial clavicle and the torn surrounding ligaments were examined. All brous tissue from the medial aspect of the clavicle (case 1 and case 3) and fracture fragments (case 2) were debrided. After SC joint and/or fracture reduction was achieved, a 1.5-mm Kirschner wire was used for temporary xation. A space posterior aspect of the superior manubrium was then bluntly created with extreme care by using a curved hemostatic forceps [9,10]. Then, the hook of the plate was inserted into the space posterior to the manubrium, the other end of the hook plate was xed on the anterior part of the medial clavicle ( Figure 1). Torn ligaments were repaired by using nonabsorbable suture (case 2). For case 1 and case 2, intraoperative image showed accurate reduction of AC joint, we treated these two cases acromioclavicular joints conservatively. For case 3, after xation of sternoclavicular joint, an incision was made over the lateral aspect of the clavicle to reveal the lateral end of clavicle, after debridement of brous tissue, the fracture fragments were reduced and xed by a locking plate. Finally, the surgical wounds were closed in layers.

Postoperative management
Following surgery, the patient's affected shoulder was placed in a sling for 4 weeks. Then, gentle Godman's pendulum exercises were started under a physical therapist supervision, active strengthening exercise began 3 months, and patients were permitted to return to their regular activity at 6 months postoperatively.

Results
The study cohort comprised three patients with three different injury patterns: a 54-year-old female (patient 1) presented with dislocations of both AC and SC joints, a 26-year-old male (patient 2) presented with fracture-dislocation of the SC joint associated with AC subluxation, and a 58-year-old female (patient 3) presented SC dislocation associated with distal clavicle fracture. Speci cally, all three patient had an anterior SC dislocation, patient 1 and patient 2 had a Type acromioclavicular joint dislocation according to Rockwood classi cation [13], patient 2 had a type 1B2 medial clavicle fracture according to Edinburgh classi cation [14], patient 3 had a type distal clavicle fracture according to Neer's classi cation [15]. Injury mechanism contained one fall form height, one crashing, and one car accident. Two patients had injury on the left side and 1 had injury on the right. All patients had closed injuries without damage to neurovascular or mediastinal structures. Two patients were associated with multiple injuries (patient 2 and patient 3).
All patients were initially treated by closed reduction. However, recurrence instability was present in each patient and therefore necessitated surgical xation. Each SC injury was xation by clavicle hook plate, AC dislocation in patient 1 and patient 2 were treated conservatively, and immediate postoperative plain radiography con rmed correct hook plate placement and accurate reduced AC. More, distal clavicle fracture in patient 3 was xed by anatomic locking plate.
With a at least of six months follow-up, each patient was quali ed for the nal evaluation. At the last follow, each fracture had solid union, and each dislocation showed no sign of recurrent instability, the mean shoulder forward exion was 153.3°±10.4°, the mean DASH score was 13.9±9.2 points. The mean Constant and Murley joint function score was 82.3±12.3 points, with 1 excellent cases and 2 good cases. And, the mean VAS score was 2.2±2.0 point.
Although patient 1 and patient 3 had mild shoulder limitation, each patient was able to resume preinjury daily activity and satis ed with their treatments.
Complications like important structures rupture, infection, hardware failure, or vital organ injury did not happen.

Discussion
Bipolar dislocation of the clavicle is rare, and surgeon's treatment experience is limited, both diagnosis and surgery are challenging for surgeon. As this injury is frequently one part of polytrauma (brain trauma, rib fracture, hemothorax, pneumothorax, scapula fracture, or chest injury) [4], bipolar clavicle injury is usually initially missed or delayed diagnosed on plain radiography because the only indication of an abnormality may be slight widening of the AC joint [16,17]. CT scanning with three-dimensional reconstructions is most valuable to get an early diagnosis, to evaluate the precise displacement of each end of clavicle, and to make a preoperative planning [5,18]. The authors recommend that whenever one end of pathology clavicle is suspected, the whole length of clavicle including both sternoclavicular and acromioclavicular joint should be examined, in such cases, CT scan would be necessary.
The mechanism of bipolar clavicle injury is still not well-known this injury is frequently a result of high-energy trauma, like a deforming force on the lateral aspect of the shoulder or a driving force squeezing the shoulders together combined with trunk torsion [8,10]. Two hypotheses have been advocated. One theory suggests two dislocations occur simultaneously, the trauma force on the shoulder is initially transformed into the elastic energy to the clavicle [19].
When the external force disappears, the clavicle relaxes and returns to its normal shape, the energy continues to conduct on both sides of the clavicle, causing each clavicle end ligaments damage and subsequent dislocation of the acromioclavicular joint and sternoclavicular joint [7,19]. And the another one proposes that an initial dislocation of the sternoclavicular joint followed by subsequent dislocation of the acromioclavicular joint [20].
Four different patterns of bipolar injury of the clavicle had been reported: (1) dislocation of both ends of the clavicle, (2) dislocation of the sternoclavicular joint with distal clavicle end fracture, (3) dislocation of the acromioclavicular joint with medial clavicle end fracture, and (4) segmental fracture of the clavicle [21]. For most oating clavicle, the medial end displaced anteriorly while the lateral end displaced superiorly or posteriorly (Rockwood type III or IV). Eni-Olotu and Hobbs [7] reported a case of inferior displacement of lateral end and superior displacement of the medial end. And, only a few of bipolar clavicle injury with posterior SC joint dislocation have been found [4,8,22,23]. Posterior SC joint dislocations and medial clavicle fractures are life-threatening injuries because of their potential to cause damage to retrosternal structures. In this study, we encountered 3 different injury patterns, and where we treated an extremely rare case of acromioclavicular joint dislocation combined with medial clavicle end fracture-dislocation (Figure 1), to the best of our knowledge, in the past few of years, only Lee et al. [21] had reported one such case.
Owing to the rarity and limited experience of this injury, treatment remains controversial and challenging. In the early stage, most authors treated their patients nonoperatively with satisfactory results [2,3,7,20,24]. However, most patients sustained deformity residual pain or instability [20]. Sanders et al. [25] reported a group of six cases with both ends dislocations, all patients treated with conservative methods initially, 4 cases required additional surgical intervention because of continuing pain, and nally got good results after AC joint reconstructions. Also, Lee et al. [21] found superior results in patients treated with surgical treatment. Thus, a consensus towards the fact that younger and active patients should be treated with surgical treatment, due to unacceptable pain, deformity, and shoulder function limitation if the anatomical reduction cannot be restored [4,10,21].
When bipolar clavicle injury is treated operatively, surgical approach to the acromioclavicular dislocation and lateral end fracture is well-described and standard procedure. Surgical options vary from internal xation (Hook plate, Kirschner, pin) to ligaments reconstruction (such as Weaver-Dunn, coracoclavicular reconstruction) [13]. However, there is no consensus on the standard treatment strategy for SC joint injury. Surgical treatment is challenging due to the proximity between SC joint and important retrosternal structures (trachea, esophagus, brachiocephalic veins, brachiocephalic artery, and brachial plexus). Many operative procedures have been described for surgical treatments, and each had its own merits and drawbacks, such as pins, Kirschner wires, Tplate xation, medial clavicle resection, and ligament reconstruction [9,12,26]. Our previous study had showed clavicle hook plate to be a very feasible option for displaced medial clavicle fracture and SC joint dislocation with several advantages, such as minimal risk of damage to retrosternal structures, dynamic xation without damage to SC joint cartilage surface, and improved xation stability for comminuted medial clavicle fracture [9]. In this study, we xed each SC joint injuries with hook plate. Meanwhile, in a report of two cases of bipolar clavicle injury, Schemitsch et al. [10] xed SC joint with clavicle hook plate, at the follow up, both patients got good outcomes. Our treatment outcome was consistent with theirs.
More, controversy still exists about the management sequence of bipolar clavicle injury. Schemitsch et al. [10] recommended initially xed the more displaced end. Whereas, in a study containing 6 operative cases and 5 conservative cases, Lee et al. [21] xed AC injuries with a hook plate rstly, and then open reduction and anterior SC ligament repair was performed after failed closed reduction of the medial end of the clavicle. Yurdakul et al.[27] and Thyagarajan et al. [22] xed the sternoclavicular joint rstly in their reports. The authors experience was consistent with the above two studies, in this present study, once the SC joint was stabilized, the AC dislocation was found to be reducible passively, the reasons might be that the sternoclavicular joint is much more incongruous because the clavicular end is bulbous in shape and the clavicular notch of the sternum is curved. Thus, the authors presume that SC xation is su cient for some part of bipolar clavicle injury, especially for cases with AC dislocation, and AC xation is not necessary unless residual instability existence.
In this study, the authors noted that a patient (Figure 2) who preoperatively presented SC dislocation associated with distal clavicle fracture sustained a slight acromioclavicular joint dislocation after a hook plating in SC joint and an anatomic plate osteosynthesis in distal clavicle, the reasons might be an inaccurate reduction of distal clavicle due to chronic injury or a hook plating under large stress. Meanwhile, the authors admit limitations of this study, such as small size of samples, lack of a control group, and short time of follow-up period. However, considering the rarity of bipolar clavicle injury, the limitations did not in uence the results.

Conclusion
Internal plating was proven to be a safe and effective treatment for bipolar clavicle injury, and only sternoclavicular joint xation might be su cient for some part of bipolar clavicle injury. However, this treatment calls for a well-trained surgeon to avoid damaging to retrosternal structures and xing under large stress.   A 58-year-old woman (patient 3) was injured in a car accident, after repair of the life-threatening injury, she came to our institute for surgical intervention because of intolerable pain in her shoulder. An anterior view (A) shows anterior dislocation of the left sternoclavicular joint. The (B) preoperative X-ray and (C) CT scan show a left anterior dislocation of the sternoclavicular joint (SCJ) and an ipsilateral Neer type distal clavicle fracture. A postoperative radiograph (D)

Abbreviations
shows the reconstructed clavicle with a hook plating in SCJ and a plate osteosynthesis in distal clavicle. Radiographs 11 months postoperatively shows the normal alignment of the SCJ, solid union of distal clavicle and a slight persistent acromioclavicular joint dislocation. (F, G) Although she had a slight pain and function limitation in her shoulder joint, she was satis ed with the treatment.