This research was approved by the Institutional Review Board of the authors’ affiliated institutions. From January 2018 to July 2020, 72 patients with operated proximal humeral fractures were admitted to our study. All patients signed written informed consent forms, including the requirement for internal fixation, and the statement of double plates when necessary. The inclusion criterion was the presence of comminuted metaphyseal proximal humeral fractures. The exclusion criteria were pathologic fractures, open fractures, fractures with neurovascular injury, fractures of >2 weeks, and those combined with other fractures involving the ipsilateral upper limb. Finally, 15 proximal humeral fractures with severe medial instability were reduced and fixed with the help of an anteromedial locking plate. Six men and nine women were included in the study, the average age of the patients was 61.53 years (range, 32–76 years), and all of them were right-handers. The left arm was affected in four patients, and the right arm was affected in 11 patients. All patients had an explicit history of trauma, including four cases of bicycle injuries, 10 cases of walking injuries, and one case of falling from height. All fractures were closed without combined injuries to the same limb. The average time from injury to surgery was 6.6 days (range, 2–14 days). Before surgery, anterior–posterior (AP) and lateral radiographs of the shoulder were taken, and additional computed tomography and 3-dimensional reconstruction images were recommended in all patients to understand the fracture patterns and the degree of displacement. The fractures were classified using the Neer system; 5 cases were three-part fractures, and ten were four-part fractures.
All the surgeries were performed by the same group of surgeons. After administering general anesthesia, each patient was placed on a radiolucent table in the beach-chair position. The entire upper extremity was prepared to allow unrestricted arm traction and rotation during the operation. A deltopectoral approach was used to expose the proximal humerus; subsequently, the cephalic vein was exposed and taken medially. The deltopectoral interval was developed by finger dissection, and a Hoffmann hook was inserted beneath the deltoid muscle. After identifying the long head of the biceps brachii tendon (LHBT) in the bicipital groove, the fracture lines were separated slightly using a periosteal elevator. The coracoacromial ligament was partly cut if necessary, and the comminution of the fracture was observed by rotating the distal humerus (Figure 1a). Later, the rotator cuff was explored, but injury was not observed in these patients. Three pairs of high-strength, non-absorbable sutures were inserted into the tendon to fix and reduce the fragments. A superior suture was used for the supraspinatus tendon, an anterior suture for the subscapularis tendon, and a posterior suture for the infraspinatus tendon as previously described  (Figure 1b). Then, the alignment of the fractures was restored by pulling down the sutures along the diaphyseal axis, distraction of the humeral shaft, and levering the humeral head using the joystick technique, followed by temporary K-wire fixation and C-arm fluoroscopy. If comminuted fracture was present in the lateral cortex without any anatomical landmark or if restoring the normal alignment using existing reduction methods was difficult due to medial instability, reduction technique involving an anteromedial locking plate was selected.
First, subperiosteal dissection was performed in the medial side of the intertubercular sulcus to expose the lesser tuberosity, the anteromedial fracture line, and the cortex distal part of the fracture. The attachment of pectoralis major was stripped for 2–3 cm and repaired by suturing to the plate or by drilling the humeral cortical bone after fracture reconstruction. If necessary, the subscapularis tendon was partially released from the lesser tuberosity. The anatomical mark is usually visible in the anteromedial fracture line. According to the residual anatomical mark or the recovery of the humeral head-shaft angle (HSA), the continuity of the anterior medial cortex was restored and fixed by using the K-wire. During the restoration, techniques such as traction of the upper arm, suture technique, and joysticks were used. Subsequently, a T-shaped 2.7-mm locking plate was placed in the medial side of LHBT. The plate was pre-bent to match the anteromedial curvature of the proximal humerus, with the T-shaped head fixed on the lesser tuberosity and the distal end fixed on the shaft. The small locking plate was approximately parallel to the shaft of the humerus crossing the anteromedial fracture line. Two and three locking screws were inserted into the proximal and distal ends of the plate, respectively, to restore and support the anteromedial cortex (Figures 1c, d).
If several bone defects existed, β-tricalcium phosphate bioceramics were implanted to maintain the normal HSA. Then, proximal humeral internal locking system (PHILOS, Synthes, Switzerland) was placed lateral to LHBT. A non-locking, bicortical screw placed in the oblong hole allowed compression of the plate against the humeral shaft and minor adjustments in the final plate positioning (Figure 1e, f). Fluoroscopy was used to evaluate the position of the plate and avoid impingement. The traction sutures were pulled through the suture holes to reduce the tuberosities prior to the insertion of the locking screw and were finally tied. It was ensured that the screws were 5 mm lower than the articular surface as far as possible and did not pass through the cartilage surface of the humeral head, which was monitored using the AP, lateral, and axillary radiographs of the shoulder joint (Figure 1g, h). At the same time, attention was paid to the use of calcar screws to further strengthen the medial support.
After the surgery, the patients were placed in a sling and were immediately encouraged to do pendulum exercises. The scope of passive activities was increased gradually over a period of 2–6 weeks. Active stretching, flexion, abduction, adduction, and pronation training were started 6 weeks after the operation. However, weightlifting with the injured arm was forbidden until bone union was observed.
Regular follow-up was done at 4, 8, and 12 weeks as well as at 6 and 12 months after the surgery until the shoulder functioning reached a plateau. Postoperative complications (infection, neurovascular injury, and flap necrosis), time of bone union, and radiation complications (loss of reduction, varus malunion, screw penetration, and avascular osteonecrosis) were evaluated. Bone union was defined as bony bridging on both views, and was confirmed by clinical examination . The functional outcomes were evaluated at the final follow-up examination according to the Constant score. Loss of reduction was defined as HSA reduction > 10° and varus malunion as HSA reduction < 120° according to the methodology of Wang .