Varus posteromedial rotatory injury (VPMRI) is a clinically particular type of elbow joint injury. Compared with the more common terrible triad of the elbow, this type of injury has a particular onset and poor prognosis. The concept of VPMRI was firstly proposed by Professor O' Driscoll in 2003, referring to the subluxation of the coronal process relative to the medial edge of trochlea caused by anterior aspect fracture or defect of the ulnar coronoid process, lateral collateral ligament (LCL) injury, widened lateral humeroradial joint, and osseous injury. This injury is mostly caused by the varus stress of elbow joint, but the X-ray film often has no apparent dislocation and other performance, which is easy to cause missed diagnosis and misdiagnosis. Many domestic and foreign literatures have reported on such injuries, but there are still some controversies about the established surgical methods. Inappropriate surgical treatment has defects such as inadequate exposure, incomplete reduction, etc. In the long-term, there are problems such as elbow joint contact stress abnormality, early degenerative disease, and elbow arthritis. The modified dual incisions joint approach has the advantages of clear surgical field, postoperative elbow stability, and higher postoperative functional satisfaction.

I. General information: From January 2012 to December 2015, a total of 19 patients with elbow varus posteromedial rotational instability were treated in Shanghai Ninth People's Hospital, including 13 males and 6 females with an average age of (40.47±9.20) years (28-61 years) . Nine cases were on the left side, and ten cases were on the right side. According to O'Driscoll classification of ulna coracoid process fracture, there were 7 cases of type II 1, 10 cases of type II 2 and 2 cases of type II 3. The causes of injuries were direct violence such as fall damage or traffic accidents. The associated injuries included 2 cases of radial head fractures (1 case of Masson type II and 1 case of Mason type I) and 9 cases of LCL injuries. The clinical manifestations were elbow joint swelling and sling varus deformity without apparent dislocation or ulnar nerve injury. II. Methods: (1) Preoperative evaluation and treatment: Preoperative evaluation required detailed medical history and comprehensive physical examination collected by the clinician. The posture of the patient at the time of injury could help to determine the extent of the damage. Skin condition, degree of swelling, presence or absence of elbow dislocation, presence of important neurovascular damage should be recorded, especially ulnar nerve injury. The anteroposterior view and lateral view of the elbow joint X-ray films should be routinely performed before the operation. If necessary, these could be examined under fluoroscopy after anesthesia. The varus, pronation and axial stress applied to the forearm could induce remarkable elbow dislocation and widened joint space. In the meanwhile, the CT scan and three-dimensional reconstruction could further confirm the fracture classification and degree. After definite diagnosis, the elbow joint was temporarily fixed in the 90° flexion and forearm functional position with long arm plaster fixed to alleviate pain, and other related preoperative auxiliary examinations were completed before the operation. (2) Surgical methods: After successful general anesthesia or brachial plexus block, the upper extremity was abducted in the supine position. The pneumatic tourniquet was used in arresting bleeding within 1 hour. The 2^nd generation cephalosporin was used for prevention of infection 30 minutes before surgery. After anesthesia, the degree of LCL injury and the instability of elbow joint were reexamined under fluoroscopy of varus stress view. Through the modified anterior approach, a longitudinal zig-zag incision was made at the level of one finger below the cubital crease. The expansion of aponeurosis musculi bicipitis brachii was partially cut open to expose the brachial artery and the median nerve via the space between musculus biceps brachii and forearm muscles. The brachialis was directly exposed through the above space, and then the coronoid process of the ulna was exposed by splitting the brachialis. During the operation, attention should be paid to the gentle traction to avoid the damage of brachial artery, median nerve and other important structures (note that the nerve is retracted to the ulnar side and the artery is retracted to the radial side) . According to the size of the fracture fragment, the type II 1 coronoid process fracture was fixed with small screws, and the type II 2 and type II 3 fractures were fixed with microplates. Two patients combined with radial head fractures were fixed with hollow compression screws after reduction. The small comminuted fragments that could not be fixed were removed, and the anterior joint capsule was repaired with the suture anchor. After the fixation of the ulnar coronoid process, the LCL was repaired with suture anchor through Kocher approach if the LCL complex was found damaged. The lateral Kocher approach was performed in the position of 90° elbow flexion. The proximal incision was cut open along the ridge of humeral external epicondyle between triceps and brachioradialis, and the distal incision was cut open through the space between anconeus and extensor carpi ulnaris. After dissecting the supinator muscle, the deep branch of the radial nerve was touched by fingers, and the forearm was placed in the position of pronation to reduce the risk of radial nerve injury. Part of the supinator muscle was detached to expose the LCL complex and the joint capsule. The avulsed ligament was repaired by anchor fixation from the origin of LCL (posterior aspect of the humerus) . As the repair was finished, the internal fixation was confirmed in position and stable under C-arm fluoroscopy. The gravity test was used to examine the stability of elbow joint, which was that the maintenance of the concentric circle structure indicated satisfactory surgical results with the affected limb in the position of extension and supination under lateral fluoroscopy. (3) Postoperative treatment: After the operation, the patient was given an adjustable elbow brace to fix the elbow joint in 90° flexion and rotational neutral position. After 48 hours, the wound was replaced with the excipient, and the early functional exercise was initiated as well, mainly the active flexion and extension. The oral Voltaren tablets were regularly given to the patients with 100 mg each time and 3 times per day to prevent heterotopic ossification as well as alleviate the pain symptoms during exercises. Passive traction training was added 6 weeks after surgery, and the elbow brace was removed 8 weeks later. Weight-bearing training started at 3 months after surgery. (4) Postoperative evaluation: The patients were followed up for in the 1^st, 3^rd, 6^th, 12^th, 18^th and 24^th months. The elbow radiograph of lateral view was taken, and the elbow joint function was evaluated according to Mayo elbow performance score during follow-ups, mainly including pain (45 points) , joint range of motion (20 points) , stability (10 points) , and daily function (25 points) . The score of≥90 points was regarded as excellent, the score of 75-89 points was regarded as good, the score of 60-74 points was regarded as moderate, and the score of <60 points was regarded as poor. Postoperative radiographic examination was conducted regularly, and the criteria were assessed according to Broberg and Morrey rating system: no abnormalities of elbow joint was regarded as grade 0, mild stenosis or small amount of callus formation was regarded as grade 1; moderate joint stenosis or moderate osteophyte hyperplasia grade 2, and severe joint degeneration and joint destruction were regarded as grade 3.

All 19 patients were followed up for 12 to 33 months (mean time 20.4 months) . All patients obtained satisfactory functional recovery. The flexion was 120°-140° (130.47°±5.45°) , the extension was 0°-16° (5.79°±4.51°) , the pronation was 75°-90° (83.42°±4.60°) and the supination 80°-90° (85.42°±2.99°) . There were 15 excellent cases (90-100 points) , 3 good cases (80-85 points) and 1 moderate case (70 points) , and the good and excellent rate was 94.7% according to Mayo elbow performance score. All patients had no chronic pain after the operation as well as complications such as elbow varus deformity, elbow dislocation, etc. There was no ossification of the elbow joint during the short-term follow-up. Eighteen patients had no degenerative change, and 1 patient had grade 1 change. There was no grade 2 or 3 traumatic arthritis.

Varus posterolateral rotational instability is a relatively intractable disease in clinical practice. Correct diagnosis and treatment of such injuries are the problem that must be faced. We can effectively fix the fracture of the medial ulnar coronoid process and repair the lateral collateral ligament complex to reconstruct the stability of elbow joint through modified dual incisions joint approach by improving the anterior incision combined with Kocher approach. After the operation, the patient obtained satisfactory treatment results in the short-term follow-up through assisted functional exercises with the brace.