Background 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.
Methods 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.
Result 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.
Concussion 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.