This retrospective study was approved by the institutional review board of the Third Hospital of Hebei Medical University and obtained all the participants' written informed consent before its commencement. We reported this study in accordance with the Helsinki Declaration and following the Strengthening the Reporting of Cohort Studies in Surgery (STROCSS).
Inclusion and exclusion criteria
The inclusion criteria were: age of 18 to 60 years, definite radiographic diagnosis of isolated Rockwood type III acromioclavicular joint dislocation, time from injury to operation < 2 weeks, and patients with complete at least 12-month follow-up assessments. The exclusion criteria were: age outside the range, open jury, old injury (≥ 2 weeks since injury), injury caused by other diseases (tendinitis, metabolic, et al.), concurrent shoulder osteoarthritis, arthropathy or any fracture, any previous operation of the injured limb, or incomplete data or follow-up < 12 months.
Surgical technique
Modified tightrope loop plate fixation (MTRLPF)
Under general anesthesia or cervical plus brachial plexus block, with patient in a beach-chair position and the affected shoulder up. The projection point of the coracoid was identified under fluoroscopy. A transverse incision 1.0–2.0 cm in length above the projection point was made to the clavicular periosteum to touch the coracoid; then a longitudinal incision 1.5–2.0 cm was made downward at the inferior edge of coracoid, and blunt dissection was preformed straight to the base of the coracoid process. Under the guidance of a self-made guide device, a 2.4-mm diameter guide needle was introduced from the center of the anteroposterior edge of the clavicle to the center of the base of the coracoid process, under fluoroscopy control. A 4.0-mm hollow drill was used to ream, then guide needle was removed and lead device was insert via hollow drill, which was removed before TightRope titanium plate (Arthrex, USA, CFDA: Import 20,173,460,186) was pushed. FiberWire loop above the clavicle was adjusted, fastened and knotted, and then the tail was cut off after fluoroscopy confirmed the satisfactory reduction. The Fig. 1A-F depicts the operative procedure process.
Open reduction and hook plate fixation (ORHPF)
Under general anesthesia or cervical plexus plus brachial block, with patient in a beach-chair position, a 6 to 8-cm incision was made along the distal clavicle to the acromion to expose the distal clavicle and the shoulder joint. Under direct vision, shoulder joint was reduced and a hook plate (Tianjin, Zhengtian, CFDA 20,173,464,301) was inserted for fixation. Shoulder joint was passively moved to confirm that there was no acromion impingement, and then acromioclavicular ligament was sutured and repaired. After surgery, the affected shoulder was abducted and fixed in a neutral position to avoid weight-bearing.
Postoperative management
Patients in both groups are asked to follow the same postoperative exercise regimen over time. From the 1st day after surgery, active fist clenching and elbow movement was started; from 3rd day, passive pendulum movement exercise of the shoulder joint was started, and affected shoulder was immobilized in abduction when at rest. Passive and active and functional exercises of the shoulder joint were started 2 to 4 weeks after surgery, until the range of motion of the affected shoulder returned to the normal. At 3 months postoperatively, weight-bearing exercises were started and gradually increased. In most cases, the hook plate is removed 6 months after surgery and can be removed early if plate fixation fails or other adverse events have occurred. The TightRope Loop Plate is not to be removed unless otherwise indicated.
Evaluation of results and data extraction
All the data of interest were extracted from the patients' hospitalization medical records, operative records and the outpatient follow-up registration at the postoperative 1, 3, 6 and 12 months. The data included demographics (age, sex, and body mass index (BMI)), injury-related variables such as time from injury to operation, involved side, injury mechanism and the coracoclavicular distance before operation, surgery-related variables such as surgical duration, incision length (for MTRLPF, sum of the both incisions length). At each outpatient follow-up at 1, 3, 6, and 12 months postoperatively, patients were asked to indicate their subjective pain degree by the visual analog scores (VAS), and complete both questionnaires, including Constant-Murley shoulder function questionnaire and the disabilities of the arm, shoulder, and hand (DASH) questionnaire, under the explanation and guidance of the doctor.
The DASH questionnaire is a validated questionnaire to evaluate patients’ ability to perform daily activities [8], including 30 items of daily activities, with a potential response score ranging from 0 which represented no disability, to 100 points which represented maximum disability.
Constant-Murley shoulder function scoring questionnaire is a validated questionnaire [9], including 4 parts: perceived pain, activities of daily living, the range of motion of the shoulder joint and the muscle strength, with scoring at highest of 15, 20, 40, and 25 respectively. The total score ranged from 0, which represented the worst, to 100 which represented the normal should function status.
Any complication occurring during operation, reported by the patients or examined at each follow-up, were noted, such as intraoperative nerve or blood vessel damage, coracoid fracture, postoperative surgical site infection, hardware loosening, loss of reduction, persistent shoulder pain, dislocation recurrence et al.
Statistical analysis
The continuous variables including age, BMI, coracoclavicular distance before and after operation, incision length, intraoperative blood loss, surgical duration, VAS score, DASH and Constant-Murley score were indicated as mean and standard deviation (SD) and the difference for each variable between two groups was evaluated by Student-t test or Mann Whitney-U test, on basis of their normality status. Categorical variables including sex, involved side, mechanism, postoperative complications were expressed as number and percentage, and the difference was evaluated by Pearson Chi-square test. Two-tailed p value less than 0.05 was considered to be statistically significant. SPSS 24.0 software (IBM corporation, Armonk, NY, USA) was used to perform all the analyses.