In 1954, Latarjet firstly reported the open procedure of coracoid transfer with conjoin tendon to anteroinferior glenoid for the treatment of anterior shoulder instability. This technology on the one hand, filled in the glenoid bone defect and restored its size; on the other hand, the conjoin tendon and part of the split subscapularis had "sling" effect and enhanced the obstacle of anteroinferior soft tissue, which significantly reduced the recurrence rate of shoulder dislocation.With the continuous improvement of arthroscopic technology, more and more literatures about arthroscopic Latarjet procedure have been reported recently. Compared with traditional open urgery, arthroscopic procedures have such advantages as small invasion, little blood loss, fast recovery, satisfactory curative effect, etc. However, the arthroscopic technique requires a long learning curve and has some certain difficulties. One is that the arthroscopic operation has multiple approaches, especially the medial approach. The biggest potential risk for the complication of nerve injury is that the approaches are too many and too close to the medial side, especially when the course of brachial plexus have mutation. The second is that it is difficult to fix the coracoid fragment parallel to the glenoid surface with screws. This often lead to the poor position of fragment or the impact of screw head on humeral head cartilage, and even cause complications such as screw loosening or withdraw, fragment fracture, fragment nonunion or absorption, etc. In order to simplify the arthroscopic Latarjet procedure, reduce the complications and improve the clinical efficacy, we adopted the modified arthroscopic Latarjet procedure of double Endobuttons anti-rotation fixation with three approaches for the treatment of patients with recurrent anterior shoulder dislocation of severe bone defect. The fragment position and healing was observed by three-dimensional CT scan. We followed up the clinical efficacy and achieved satisfactory results.

(1) Operation steps.①Coracoid osteotomy and preparation. After general anesthesia, the patient was in beach chair position with routine disinfection and draping. A longitudinal incision of 3 cm was made in the center of coracoid. The coracoid was exposed to cut off the coracoacromial ligament and most of the pectoralis minor muscle. The coracoid was osteotomized for 2 cm to facilitate trimming, and the coracoid pedicle was left 3-4 cm to prevent its impact with axillary nerve. The 3.0 mm and 2.4 mm bone tunnels were drilled respectively at a distance of 6 mm, and the distal pedicle bone tunnel (2.4 mm) was penetrated with PDS suture. The Endobutton (Smiths & Nephew, USA) was placed on the surface of proximal pedicle bone tunnel (3.0 mm) with 3 high tensile-strength sutures penetrated through the central 2 holes to set aside. The other high tensile-strength suture was penetrated through the lateral holes to tie the knot with the suture from anti-rotational anchor. After trimming the coracoid process, the incision was partially closed with 8 mm gap left for A approach which was located right at the anterosuperior side of subscapularis tendon.②Subscapularis split and glenoid bone bed preparation. The lateral approach C was established under arthroscopy through the standard posteior approach (B) . The glenoid bone defect and Hill-Sachs lesion were assessed after joint exploration, and a 2.5 mm hole was drilled on the glenoid for positioning at the direction of 3:00. The C approach was used for observation, and the A approach was used for planer and radiofrequency coblation. After the positioning of switch rod through B approach, the subscapularis was split at the same level of glenoid and the axillary nerve was exposed for protection. The glenoid was observe through the subscapular incision, and then the bone bed of glenoid was refreshed as well.③Transposition and fixation of coracoid fragment. A double cylinder locator of 8 mm was inserted through the switch rod. This locator was 120 mm in length and consisted of 2 hollow titanium alloy tubes at a distance of 5-10 mm which were connected by the titanium alloy of 3 mm thick. One of the hollow tube was 4.5 mm in diameter and used for switch rod insertion, while the other tube was 2.5 mm in diameter and used for the 2.4 mm guide pin insertion. The design and use of this locator were simple and safe. Under the guidance of switch rod, the glenoid was drilled at the position of 5:00 with a guide pin of 2.4 mm after the preoperative CT measurement of its anteroposterior diameter. Then an Endobutton drill of 4.5 mm was used to expand the hole, through which the PDS suture was penetrated to set aside. A Twinfix anchor (Smiths & Nephew, USA) of 2.8 mm was implanted parallel and superior to the bone tunnel of the glenoid to prevent fragment rotation.The small incision of coracoid osteotomy was open to pull out the PDS suture as well as the suture of anchor. After that, the suture of anchor penetrated through the distal bone tunnel. Under the guidance of PDS suture, the 3 high tensile-strength sutures from the preset Endobutton were pulled out through B approach. The coracoid fragment was pulled into the joint and attached to the glenoid. The other Endobutton was penetrated with high tensile-strength sutures, and it was tied and fixed through B approach. The high tensile-strength sutures and the suture of anchor were tied for fixation with Double-Pulley technique to prevent Endobutton rotation.Finally, the B approach was used to observe the relationship between the surfaces of fragment and glenoid. If necessary, the fragment should be shaped to match glenoid. The articular capsule was not sutured. (2) Rehabilitation plan.The shoulder was immobilized with brace in 30° of abduction and 0° of external rotation for 2 weeks, and in the meanwhile, the early active exercises of hand, wrist and elbow were encouraged. The passive pendulum exercise of shoulder joint was allowed 2 weeks later. With the removal of brace, the active rehabilitation training was conducted under the guidance of physicians. The active exercise of biceps brachii muscle with high intensity was forbidden with 6 months after operation. (3) Postoperative evaluation.The position of coracoid fragment was observed by three-dimensional CT scan. From the front view of glenoid, the best position was where the center of fragment was at the direction of 4:30. The range of center was from 2:00 to 5:00, and the center was considered high if it was higher than 3:00 and low if it was lower than 5:00. From the cross-sectional view of CT scan, the best position was where the fragment was even with glenoid or below <5 mm. The fragment was considered to be medial if it was below >5 mm and lateral if it was higher than the glenoid. If the patient complained mainly about the feelings of shoulder instability such as shoulder laxity or dislocation, etc. or both the Apprehension test and the Relocation test were positive, the operation was considered a failure. The shoulder joint function was evaluated by rating scale of the American shoulder and elbow surgeons (ASES) , ROWE score and Walch-Duplay score. The operative time was recorded as well. (4) Statistical analysis.The data were expressed as mean value±standard deviation, and the software of SPSS 18.0 was used for statistical analysis. The difference was statistically significant (P <0.05) .

From October 2014 to October 2016, a total of 50 patients with recurrent shoulder dislocations of severe bone defects received arthroscopic Latarjet procedure of double Endobuttons anti-rotation fixation with three approaches. There were 39 males and 11 females (45 left shoulders and 5 right shoulders) with an average age of (27.2±2.1) years (15-45 years old) . The average time from primary dislocation to surgery was (24.3±12.7) months (6-120 months) . The average percentage glenoid bone defect was (20.1%±2.9%) (18%-39%) . The average episodes of shoulder dislocations was (16.1±2.4) times (3-40 times) . There were 4 revision cases, including 3 recurrent cases after Bankart repair and 1 recurrent case of multiple directions instability (MDI) after capsule constriction. The operation time ranged from 57 min to 150 min with an average of (105±38) min. (1) Postoperative posititon of coracoid bone fragment. Glenoid surface observation: according to the standard of fragment center at the position of 4:30, there were 45 cases of good position, 2 cases of high position and 3 cases of low position. Cross-sectional observation: there were 43 cases of good position, 1 case of medial position and 6 cases of lateral position. It was worth noting that the coracoid fragments which were superolateral to the glenoid in 6 patients had been moulded and become even with the glenoid during CT examination of 6 months after operation. (2) Postoperative absorption and healing of coracoid fragment.There were different levels of coracoid fragment absorption, and the stabilization time was 2-6 months with an average of (3.3±0.6) months after operation. The absorption ratio was 15%-60% with an average of (27.5±3.8) %. Thereinto, 8 cases had a ratio of <20%, 25 cases had a ratio of 20%-30%, 35 cases had a ratio of 30%-40% and 5 cases had a ratio of >40%. All the patients achieved fragment union 6 months after operation or revision without soft tissue healing or partial healing. (3) Postoperative clinical efficacy evaluation.The patients were followed up for 6-24 months with an average of (13.2±3.6) months. In the preoperative and final follow-ups, the mean ASES score was (80.2±16.2) points vs. (95.2±5.6) (P <0.05) , the mean ROWE score was (40.2±9.8) vs. (94.5±2.7) (P <0.05) , and the mean Walch-Duplay score was (67.5±10.2) vs. (95.6±3.2) (P <0.05) . All the patients returned to normal life, and compared with pre-operation, 45 (90%) patients had more intense exercises. No recurrence of shoulder dislocation or instability occurred, and the Apprehension test and the Relocation test were all negative.

The modified arthroscopic Latarjet procedure of double Endobuttons anti-rotation fixation with three approaches was adopted for the treatment of recurrent anterior shoulder dislocation with severe glenoid bone defect. With this technique, not only were the operation process and surgical instrument simple, but also the coracoid fragment was in accurate position with high healing rate. As this technique reduces the majority of arthroscopic approaches and reduces the risk of potential nerve injury, it can be a reliable and effective alternative to traditional Latarjet procedure.