孟氏骨折是由Monteggia于1814年提出，指尺骨上1/3骨折合并桡骨头前脱位的一种联合损伤。1967年Bado认为桡骨头各方向脱位合并不同水平的尺骨骨折或尺桡骨双骨折都是孟氏骨折，并将其分为4型。I型：任何部位的尺骨骨折向前成角合并桡骨头前脱位，儿童多见。Ⅱ型：尺骨干骨折向后成角，桡骨头后外侧脱位，多见于成年人。III型：尺骨干骺端骨折向外成角，桡骨头向外或前外脱位，多见幼儿和年龄较小的儿童。Ⅳ型：尺桡骨近1/3骨折、桡骨头前脱位，成人、儿童均可发生。对于新鲜孟氏骨折的治疗要重视尺骨的解剖复位。尺骨正常有约6°向后弧度，恢复该弧度对桡骨头复位及维持稳定性至关重要。尺骨轻度的向后成角有利于桡骨头稳定，是良性成角。在孟氏骨折的治理中通常先复位桡骨头再复位尺骨骨折。绝大多数桡骨头脱位是从完整的或部分撕裂的环状韧带脱位，不是环状韧带完全撕裂，通常不影响桡骨头复位。软组织嵌入影响桡骨头复位情况极少，需切开清理，通常不需要重建环状韧带。成人陈旧I型孟氏骨折对于桡骨头脱位的处理应遵循以下原则：功能良好者通常不做处理，以免影响功能；对于功能不好者行手术治疗。手术治疗时应严格选择病例（桡骨头变形不明显，术前按压可部分复位）；对于陈旧I型孟氏骨折功能受限者（如伤后时间短可重新复位固定）恢复甚至加大尺骨向后成角是成功的关键。单纯行环状韧带重建不能成功，甚至严重影响功能。伤后时间长且影响功能者可行桡骨头切除以改善功能。

Acromioclavicular dislocation is a common clinical injury . Conservative treatment is usually applied for Rockwood types I and II, while Rockwood types III-V are mainly treated with clavicular hook plate or button plate. Although clavicular hook plate is simple to operate, there are some complications that are difficult to overcome. Moreover, the removal of plate is required. TightRope overcomes many drawbacks of clavicular hook plate and is minimally invasive. Thus, this strategy is widely used. However, the button plate treatment of acromioclavicular joint dislocation requires higher technique. Furthermore, there will also be some complications.

1.The Object of Study: From January 2014 to April 2018, 77 cases of Rockwood type III acromioclavicular joint dislocation were treated with TightRope (Arthrex, USA) button plate, including 54 males and 23 females. The age ranged from 20 to 72 years with an average of 48.31 years. As all cases are unilateral, 35 cases had the right side affected, and 42 cases had the left side affected. Among them, there were 16 cases of traffic injury and 61 cases of falling injury, and all the dislocations were fresh. All patients were diagnosed by shoulder X-ray, and the main physical examination was positive. The time from injury to operation ranged from 3 to 144 hours. 6 cases failed. 2. Operative Method: The patient was in supine position with shoulder pad under the affected side. An 2-4 cm incision was made transversely on lateral clavicle above corocoid . The skin, subcutaneous, deep fascia and platysma cervicalis were cut open layer by layer , and a small amount of deltoid clavicle attachment was dissected to reveal the lateral segment of clavicle and the coracoclavicular ligament. A 2.0 mm guide needle was used to drill through clavicular shaft to the base of coracoid process. After satisfactory position was confirmed with C-arm fluoroscopy, a 4.0 mm hollow drilling was used to build the tunnel of clavicle and coracoid . TightRope rectangular buttons were penetrated through the skeletal tunnels with the help of pulling guide wire. As the rectangular buttons were confirmed to be located below coracoid process under fluoroscopy, a cable was tightened to make the subcoracoid buttons horizontal. In this way, the buttons were stuck in the cortex below coracoid process based on the preoperative design. Later, the adjustment of fiberwire tension and the knot fixation were carried out. The reduction was satisfactory under fluoroscopy, and the wound was closed layer by layer. 3. Postoperative Management: On the first postsurgical day , slight shoulder swing and vertical arm circle exercise were started. Passive exercise was allowed. Patients were encouraged to lift the affected side in a tolerable range using the healthy side (without angle restriction) . At rest, the affected limb was in passive sling. Four weeks later, all-directional active activities were encouraged until the ROM returned to normal, and daily activity was gradually resumed. Normal weight-bearing was permitted after three months. Follow-up was made regularly after the surgery, and rehabilitation guidance was given. 4. Evaluation Method: After 3 months’ follow-up, the Constant score system was used: including pain (15 points) , daily activity (20 points) , shoulder range of motion (40 points) and strength (25 points) . Full score 100, excellent (> 90) , good 80-89, medium70-79, poor < 70. 5. Failure criteria: (1) X-ray showed that the degree of dislocation of acromioclavicular joint was Rockwood II or above; (2) Fracture of coracoid process or clavicle resulted in loss of stability on one side of the plate; (3) Imaging comparison indicated that the plate was displaced or not fixed in the bone structure; (4) Shoulder movement was limited at 3 months after surgery, and shoulder pain occurred during passive movement.

All patients were followed up for 3 to 32 months with an average of 14.30 months. The constant score was (93.86±5.59) 3 months after the surgery. There were 68 cases of excellence , 6 cases of good , 2 cases of medium and 1 case of poor. Among them, there were 6 failed cases. The Constant score was (79.17±7.33) 3 months after the surgery. There were 1 case of excellence, 2 cases of good, 2 cases of medium and 1 case of poor . No revision operation was performed in the cases. The causes of failure included 3 cases of skewed construction of bone tunnel (2 cases with the tunnel not located in the center of coracoid process basement and 1 case with the tunnel on the anterior portion of clavicular end) , 2 cases of improper operation (1 case of incorrect placement of button plate and 1 case of multiple-position drilling during the operation) and 1 case of excessive reduction of acromioclavicular joint.

Currently , there are many treatment options for Rockwood type III acromioclavicular joint dislocation. There are complications or limitations in various surgical procedures reported in literature. For example, as the hook plate is commonly used, subacromial impingement syndrome will easily occur after the surgery, resulting in bone abrasion, osteoporosis, absorption or even fracture. Rockwood type III acromioclavicular joint dislocation is the simultaneous rupture of acromioclavicular ligament and coracoclavicular ligament. The acromioclavicular joint is unstable both horizontally and vertically. Therefore, the main purpose of surgical treatment of acromioclavicular joint dislocation is to restore the normal anatomical relationship of acromioclavicular joint and to reconstruct its stability. Among them, the coracoclavicular ligament is one of the most important structures to maintain the stability of shoulder joint. It plays an important role in maintaining the static structure and dynamic balance of scapular ligament. Repairing or reconstructing coracoclavicular ligament is the key point for the surgical treatment of acromioclavicular joint dislocation. TightRope technology can effectively reconstruct coracoclavicular ligament, which has more advantages in biology. Thus, it has been used more and more in recent years. The advantages of TightRope's reconstruction of coracoclavicular ligament are: (1) small incision, small tissue trauma and no extensive dissection during operation; (2) The anatomical reconstruction of coracoclavicular ligament is more in line with the biological characteristics of acromioclavicular joint, and the incidence of postoperative pain and discomfort is low, which is conducive to postoperative rehabilitation; (3) no secondary surgical removal is required. However, TightRope technology has its own drawbacks . There were 6 cases of failure in this group. The causes of failure were analyzed as follows: (1) skewed bone tunnel construction. In TightRope's operation, the acromioclavicular joint is generally reduced first, and then the clavicular tunnel is constructed from clavicular end to coracoid process base. However, the rigid obstruction of clavicle to drill bit and the operation angle will lead to the deviation of guide pin positioning. In this group, 2 cases suffered from avulsion of the lateral margin of coracoid process or the steel plate cutting into coracoid bone during functional exercise due to the deviation of coracoid drilling from the center of basement. In addition, for the location of the insertion hole at clavicular end, most scholars recommend to drill 1/3 of the anterior and middle clavicle. Baker et al. studied the effect of the position of clavicular hole on acromioclavicular joint. It was found that the closer the foramen was to the front, the smaller the displacement of acromioclavicular joint was. However, if the position was too far ahead, the holding force of clavicular end plate will be reduced, and the shear force of cable to clavicle will be increased. In this group, one case failed because of the anterior position of clavicular end tunnel. (2) improper operation: repeated positioning or drilling of Kirschner wire can damage the bone of clavicle and coracoid process, which leads to the decrease of bone strength. In addition, due to improper operation, the failure of loop plate being effectively fixed below coracoid process will lead to loss of reduction. (3) Overreduction: The normal coracoclavicular space was 6-14 mm with an average of 10 mm. TightRope technology restores coracoclavicular spacing by adjusting the tension of FiberWire loop. In practical application, the tightening degree of coracoclavicular ligament depends entirely on subjective feeling and rough measurement of the operator, so there might be errors in reconstructed coracoclavicular ligament. Some scholars emphasized that excessive reduction should be given in order to avoid loss of reduction. However, we found that excessive reduction can also cause high tension of the loop, which increases the shear force of loop steel plate on clavicle and coracoid process and leads to the instability of steel plate during rehabilitation exercise after the operation. (4) Osteoporosis: In patients with osteoporosis, osteolysis under the steel plate can easily lead to plate slippage. This technique is not recommended for the patient with osteoporosis. To sum up, TightRope's elastic fixation for acromioclavicular dislocation is more in line with the concept of modern orthopaedic biological fixation. This technique has achieved certain clinical effects. Through the analysis of failed case, however, it is also found that this technique has certain drawbacks . The causes of failure may be severe osteoporosis, skewed tunnel construction, excessive joint reduction and so on.

Accounting for 9% to 12% of all shoulder injuries and 3.2% of all joint dislocations, acromioclavicular joint (ACJ) dislocation is a common injury. There are many surgical treatments for ACJ dislocation, among which the reconstruction of coracoclavicular ligament has been accepted by the majority of orthopedic doctor. However, pain and loss of function are results of all kinds of surgery, especially for those heavy manual workers. Therefore, the gold standard treatment for ACJ dislocation still remains controversial.

1. Research objects: From 2009 to 2016, we treated 62 patients (54 males and 8 females) with ACJ dislocation via single and double bundle coracoclavicular ligament reconstruction. The mean age was (53±8.1) years. 28 cases had the right side affected, and 34 cases had the left side affected. There were 29 cases of fall, 20 cases of car accident, 6 cases of sports injury, 3 cases of fall injury at high place and 4 cases of other injuries. The condylar fracture and mutation were excluded. Rockwood classification: 35 cases of degree III, 8 cases of degree IV, 19 cases of degree V; Injury to operation time: 59 cases within 2 weeks, 3 cases over 3 weeks; Surgical method: 51 cases of single bundle reconstruction of coracoclavicular ligament (Figure 1) , 11 cases of double bundle reconstruction (Figure 2) . 48 patients were reconstructed with single bundle Endobutton, and 14 patients were reconstructed with Arthrex AC Joint TightRope (3 single bundle cases and 11 double bundle cases) . 2. Surgical approach: The patient was put in supine position or beach chair position under nerve block or general anesthesia. A 3-4 cm incision was cut along the outer end of clavicle. The acromioclavicular joint was revealed, and the broken joint disc was cleaned. Then, the reduction of acromioclavicular joint was achieved. The reduction criterion was that the leading edge of outer clavicle reached the end of coracoacromial ligament, and the outer edge was pressed down to the inner side of acromion without gap. A 1.5 mm Kirshner wire was used to fix the acromioclavicular joint from front to back percutaneously (avoiding the tunnel) ; then, a 2 cm vertical incision was made on condyle, entering the medial side of conjoint tendon and reaching the flat surface under condyle by finger. With finger as guidance, the front of the flat surface or the posterior portion of condyle was aimed. For the single bundle group, a 2.0 mm Kirschner wire was used to perforate the condyle from the midpoint of the 35 mm outer end of clavicle, and the 4.0 mm diameter drill was used for drilling. For the double bundle group, a 2.0 mm Kirschner wire was used to perforate the condyle from the midpoint of the 40 mm outer end of clavicle, and the 4.0 mm diameter drill was used for drilling. Later, a drilling was made at the midpoint of the 20 mm outer end of clavicle with 4.0 mm drill. The clavicle had two channels, and the condyle had one single channel. A double-strand steel wire of 0.8 mm was taken out from the clavicle side to the condyle side through the channel. Then, the titanium plate for each group was fixed. Finally, the condyle side wire was fixed on conjoint tendon surface, and the acromioclavicular joint capsule was repaired and strengthened. As the Kirschner wire was buried in soft tissue, the incision was sutured. 3. Postoperative treatment: The limb was suspended for 3 to 4 weeks with triangle towel postoperatively. On the second postoperative day, the active function rehabilitation of the fingers, wrists and elbow joints were performed. On the third day, the passive shoulder joint pendulum exercises could be started. The digital radiography (DR) of 2, 3, 6 months postoperatively were observed to evaluate the acromioclavicular joint reduction. The Kircher wire was removed 6 to 8 weeks after surgery. limb support and lifting weight were prohibit within 2 months. Independent activities were allowed after 3 months. 4. Efficacy evaluation: The Karlsson and Constant-Murley criteria were used to evaluate the recovery of shoulder function in patients 1 year after surgery. 5. Statistical analysis: Statistical analysis was performed using SPSS 13.0 software. The measurement data were expressed as±s, and the paired t test was used. P<0.05 was considered statistically significant.

All the incisions healed during the first stage, and there was no internal fixation breakage, shedding or failure. No complication such as iatrogenic condyle/clavicular fracture or vascular/nerve injury occurred. All patients were followed up for 1-7 years with an average of 2.3 years. According to the Karlsson evaluation criteria, there were 57 cases of excellence, 1 case of good and 3 cases of acceptable, and the excellent and good rate was 95% 1 year after the operation. The total and section scores of Constant-Murley shoulder function were significantly better than those before the surgery (P mean < 0.01) . There were two cases of internal fixation failure. In one case, the condyle channel was deviated from the midpoint, which caused the rupture of lateral wall. The other case was caused by poor patient compliance. There were two cases of acromioclavicular joint osteoarthritis, and all were operated with single-bundle reconstruction. Postoperative stress bone resorption and osteolysis were common in the clavicular channel, the single-bundle reconstruction group and the patients with large diameter and osteoporosis. Two cases of heterotopic ossification occurred around the reconstructed coracoclavicular ligament.

ACJ dislocation is a common disease in orthopedics, and the postoperative complications are receiving increasing amount of concern. The clinical research has been carried out in terms of anatomy and biomechanics. In this study, we used single and double bundle coracoclavicular ligament reconstructions to treat ACJ dislocation. The operation was simple and minimally invasive, and the clinical results were satisfactory.