Since 2003, the clinical attention paid to anteromedial facial fracture of ulnar coronoid process has been greatly increased with newly proposed Regan-Morrey classification, O'Driscoll, et al. Compared to the posterolateral rotatory instability of elbow, O'Driscoll, et al. proposed a concept of "posteromedial rotatory instability of elbow" for the anteromedial facet fractures of ulnar coronoid process. This concept helped to understand and interpret special damage pattern. As this pattern of injury is rare, there are few current studies and literature reported, and the ideal surgical indications, methods and techniques have not yet been determined.

(1) General information: From April 2011 to July 2014, 9 cases (6 males and 3 females) with anteromedial facet fracture of ulnar coronoid process received surgical treatment, and the clinical data were retrospectively analyzed. Their ages ranged from 20 to 62 years old, and the mean age was 41 years old. The causes include 3 cases of fall injury, 1 case of bicycle accident, 3 cases of electric bicycle injury and 2 cases of motor accident. All the fractures were fresh closed without neurovascular damage. The time from injury to surgery ranged from 4 to 12 days with an average of 7.2 days. One case had the history of elbow joint dislocation. According to O'Driscoll classification, all the cases were type 2, including 1 case of subtype 1, 5 cases of subtype 2 and 3 cases of subtype 3. There were 4 cases of avulsion fractures of humeral lateral epicondyle involving the lateral collateral ligament of elbow joint, and the other 5 cases were confirmed with the avulsion of lateral collateral ligaments. The patients with olecranon fractures or terrible triad of elbow were excluded from this group. Among them, 1 case combined with ipsilateral distal radial fractures received conservative treatment with external splint fixation. Before the operation, all the patients underwent three-dimensional CT reconstruction of elbow joint extended in 30° to confirm the diagnosis of fractures and subluxation. Based on the result, 2 cases had subluxation of elbow joint, and 6 cases were found with widened humeroradial joint. (2) Methods:After brachial plexus block combined with general anesthesia, the patient was placed in supine position with pneumatic tourniquet tied on the affected upper arm. The varus, internal rotation and axial stress test of elbow joint were performed under fluoroscopy with C-arm machine. There were 1 case of elbow dislocation and 8 cases of subluxation and widened humeroradial joint space. For 2 cases, the medial cutaneous incision of elbow joint was performed to locate and protect the medial cutaneous nerve and ulnar nerve of forearm. The medial collateral ligament and ulnar coronal fracture fragments were revealed through the spatium between flexor carpi ulnaris and pronator teres. The joint capsule connected with ulnar coronoid process fragments should be retained, and the blood clot and free cartilage fragments were debrided as well. At, one case of was treated for ulnar coronoid fracture fixation and repair of anterior joint capsule. The fixation of ulnar coronoid process and the repair of anterior joint capsule were performed with a 2.0 mm screw and a 3.5 mm suture anchor in 1 case of O'Driscoll type 2 subtype 1 fracture at 45° of elbow flexion. The same procedure was carried out with two 3.5 mm suture anchors in 1 case of O'Driscoll type 2 subtype 2 fracture. "L-shaped" anterior incision was made in 7 cases, and the medial antebrachial nerve and anterior cubital vein were found and protected. The bicipital aponeurosis was carefully cut open, and the brachialis was exposed through the space between brachial arteriovenous and median nerve. Part of the brachialis insertion was cut open from its medial side. By pulling the biceps, brachial arteriovenous and brachialis to the lateral side and the pronator teres and median nerve to the medial side, the fracture of ulnar coronoid process was revealed and reduced under direct vision and fluoroscopy with 1.0 mm Kirschner wire for temporary fixation. Attention should be paid to maintain the joint capsule connected with ulnar coronoid process fragments. In 1 case of O'Driscoll type 2 subtype 2, a 3.5 mm and a 2.8 mm suture anchors were used for the fixation of ulnar coronoid fracture and the repair of anterior joint capsule. In another case of O'Driscoll type 2 subtype 2, a 2.0 mm LC-DCP supporting plate was applied for fixation. In other 2 cases of O'Driscoll type 2 subtype 2 fractures, a 3.0 mm hollow screw and a 2.0 mm LC-DCP supporting plate were used to fix the tip of coronoid process. In 1 case of O'Driscoll type 2 subtype 3 fracture, a 3.5 mm suture anchor was applied to fix anterior joint capsule, and the Hotchkiss "over-the-top" approach was used to fix the fracture with two 3.0 mm hollow screws. In another case of O'Driscoll type 2 subtype 3 fracture, a 3.0 mm hollow screw was adopted to fix the tip of coronoid process. With the Hotchkiss "over-the-top" approach, the fracture was fixed with a 2.0 LC-DCP supporting plate and a 1.0 mm Kirschner wire, and the anterior joint capsule was repaired with a 2.8 mm suture anchor. In another case of O'Driscoll type 2 subtype 3 fracture, a 3.0 mm hollow screw, a 2.0 LC-DCP supporting plate and a 2.0 mm screw were used for fixation. Elbow joint lateral approach (Kocher approach) was used in 9 cases. The supinator muscle and the deep branch of radial nerve were revealed and protected through the space between anconeus and extensor carpi ulnaris. The lateral collateral ligament was explored to found the avulsion or small avulsion fractures of lateral epicondyle of humerus. With careful dissociation of lateral collateral ligament, a 5.0 mm (7 cases) or 4.5 mm suture anchor (2 cases) was placed at the rotational center of humeral ectepicondyle, and the lateral collateral ligament was repaired with its suture via knitting stich or improved Mason-Allen suture technique. Meanwhile, the anterolateral joint capsule and torn common extensor were repaired at the same time. Cantilever test was performed at 0o of elbow extension. Satisfactory reduction was confirmed with anteroposterior and lateral radiographs under fluoroscopy. The match of humeroulnar joint and humeroradial joint was concentric. Resistance training was gradually conducted 6 weeks after surgery. Within 4 weeks, shoulder abduction in standing position was forbidden to avoid varus stress on elbow joint. Starting from the 1st postoperative day, oral Indomethacin sustained release capsule was used for 4-6 weeks to prevent heterotopic ossifications. (3) Postoperative treatment: The affected limb was immobilized at 90° of elbow flexion with posterior long arm brace, and the forearm was in neutral position. The external fixation duration was 4 to 6 weeks. Continuous cold press was applied for 3 to 5 days, and later for 30 minutes after functional exercises. On the 2nd postoperative day, the patient was in the lateral position of affected side with 90° of shoulder abduction to perform the active flexion and extension of elbow joint as well as forearm rotation at 90° of elbow flexion 2 or 3 times a day. After 6 weeks, resistance exercise was gradually initiated. Shoulder abduction in standing position should be forbidden within 4 weeks to avoid varus stress in the elbow joint. The sustained-release capsules of oral indomethacin were taken for 4 to 6 weeks with 75 mg/d from the 1st postoperative day to prevent heterotopic ossification. (4) Efficacy evaluation index: Regular follow-ups were performed on the 1st, 2nd, 3rd, 6th, 12th, and 18th months after surgery, and once every year later. The anteroposterior and lateral X-ray films of elbow joint were taken to observe fracture healing, internal fixator, heterotopic ossifications and post-traumatic arthritis. The Broberg-Morrey scaling system was used to evaluate elbow joint function, including range of motion, muscle strength, stability and pain. The total score was 100 points with 95-100 points considered excellent, 80-94 points considered good, 60-79 points considered moderate and 0-59 points considered poor. The level of pain was assessed with visual analog scale.

All the incisions of this group achieved primary healing without surgical complications such as infection, neurovascular damage, et al. Nine patients were followed up for 12 to 48 months with an average of 25.6 months. X-ray films showed that all fractures healed. During the follow up, there were no complications such as failure of internal fixation, instability of elbow joint, post-traumatic osteoarthritis, et al. The ranges of motion for the last follow-up were: 0 to 10° of extension with an average of 1.1°; 110 to 135° of flexion with an average of 128.9°; 40° to 70° of forearm pronation with an average of 61.1°; 80 to 90° of supination with an average of 88.9°. According to Broberg-Morrey elbow function scaling system, the scores ranged from 82 to 100 points with an average of 95 points; the excellent and good rate was 100% with 6 cases of excellent and 3 cases of good. The scores of VAS ranged from 0 to 2 points with an average of 0.7 points. 3 cases of mild heterotopic ossification occurred in the medial elbow joint and the anterior elbow joint respectively.

The anteromedial facet fractures of ulnar coronoid process with lateral collateral ligament injury of elbow joint should be focused and identified. For patients with posterolateral rotatory instability of elbow, the reduction of fracture through anterior or medial approach, the repair of anterior joint capsule by fixation with buttress plate, suture anchor or screw and the repair of lateral collateral ligament with suture anchor through posterolateral approach could achieve satisfactory effect with early postoperative exercise.