The “CS” 2-Wire Technique, A Novel Way to Stabilize the Unstable Pediatric Extraarticular Radial Neck Fracture

Multiple strategies exist for the reduction and fixation of unstable pediatric extraarticular radial neck fractures, but consensus remains elusive. Although various techniques for stabilization have been proposed, each carries its own set of associated challenges. Closed reduction technique for radial neck fracture may fail in a subset of cases.1 The percutaneous Kapandji leverage technique2 effectively reduces the fracture but may not provide sufficient stabilization, often necessitating additional pinning and carries the risk of posterior interosseous nerve (PIN) injury. Transcapitellar K-wire fixation carries the risk of wire failure, including bending or breakage, particularly in the case of highly unstable fractures.3 This modality of fixation also predisposes the radial head to avascular necrosis.4 The violation of the radiocapitellar joint is also an unattractive feature of this technique, thereby increasing the risk of poor outcomes, including joint stiffness and posttraumatic arthrosis. Intramedullary fixation, as advocated by Metaizeau et al,5 allows for closed reduction of radial neck fractures, thereby minimizing the complications associated with open reduction, such as joint stiffness and avascular necrosis (AVN) of the radial head. However, the fixation achieved through this technique may be insufficient and can potentially be associated with secondary displacement and loss of reduction (Fig. 1). This poses a significant risk to union, which has adverse effects on the range of motion of the elbow and functional outcome.6,7 In addition, distally based flexible nail insertion sites carry risk to the dorsal radial sensory nerve or the extensor pollicis longus (EPL) injury, depending on the chosen technique.8FIGURE 1: Illustrative case example showing limitations of traditional management techniques for an unstable pediatric extraarticular radial neck fracture. (A) Grossly displaced closed radial neck fracture in an acute setting. (B) Intraoperative fluoroscopic images demonstrating acceptable alignment following closed reduction. (C) One week follow-up radiographs demonstrating loss of reduction prompting surgical intervention. (D) Intraoperative fluoroscopic images of fracture stabilization using the Metaizeau technique. (E) One week follow-up radiograph demonstrating loss of reduction as a consequence of inadequate stability of fixation.To address these challenges, we propose a novel intramedullary technique designed to stabilize the radial neck fracture adequately while minimizing disruption to the adjacent periosteum, blood supply, and radiocapitellar joint, thereby possibly limiting the known complications associated with the aforementioned techniques. PRINCIPLE This technique involves retrogradely placing 2 intramedullary wires across the fracture site to improve rotational and translational stability. The first wire, with a sharp curve at the tip and a gentle curve along the length of the bone, with its apex corresponding to the natural apex of the radius. This wire is inserted distally and advanced proximally to just cross the fracture site. The second wire follows a similar process but is rotated 180 degrees in the opposite direction while advancing across the fracture (Fig. 2). To facilitate the passage of the second wire, there are 2 alternative methods for creating the bend for S-shape wire: (1) gradually bending the wire outside the bone as it is advanced, and (2) creating the S-shaped before placing the wire in the bone. The diametrically opposite bending of the tips of the wires ensures maximum purchase of the radial head, which provides more stability than the traditional Metaizeau technique.FIGURE 2: Diagrammatic representation of the technique. (A) Displaced radial neck fracture. (B) The C wire is introduced to engage the lateral aspect of the radial head. (C) The S wire is introduced to engage the medial aspect of the radial head.In addition, the 2-wire configuration can also be used for assisting in fracture reduction. The fracture pattern may be such that rotation of a single wire is not enough for achieving and/or maintaining the reduction, such that the wire may escape through the fracture, or the radial head may rotate/translate on the tip of the first wire inserted. By using 2 wires and successive shuttling and maneuvering, reduction can be obtained and maintained (Fig. 3).FIGURE 3: (A) Severely displaced radial neck fracture: the patient sustained a severely displaced radial neck fracture, characterized by marked malalignment of the radial head in relation to the shaft. (B) Initial attempt at reduction with assisted K-wire: closed reduction was attempted using K-wire assistance. (C) Intramedullary wire insertion and continued malalignment: an intramedullary wire was inserted to stabilize the fracture, but following its placement, residual translation and angulation were noted. Attempts at further correction using K-wire assistance were unsuccessful. (D) Shuttling technique with wire for reduction: demonstrating shuttling technique for persistent malalignment, the “CS” technique was adopted. This technique involved successive shuttling of wires to improve the reduction. A second K-wire was placed in the metaphyseal bone, while the first wire remained engaged in the subchondral bone of the radial head. Through controlled rotational manipulation of the fracture fragments, the angulation was corrected. The second K-wire was utilized to further refine the reduction by rotating the fracture fragment and addressing any residual angulation. (E) Final reduction and stabilization: after achieving an acceptable reduction, both wires were carefully adjusted. The wires were oriented so that they engaged approximately one third of the radial head, ensuring adequate stabilization and minimizing the risk of redisplacement. The successful reduction was confirmed radiographically, with satisfactory alignment of the radial head and neck.To ensure the construct’s stability, particular attention is given to the spread of the wires on imaging. On either anteroposterior or lateral radiographs, the wires must demonstrate sufficient divergence (ideally 180 degrees) to prevent them from acting as a single construct. This divergence is crucial for maintaining rotational and translational stability by optimizing effective multiplanar fixation. The success of the “CS” 2-wire technique relies on the correct positioning of these wires. TECHNIQUE Position: Supine with the shoulder abducted and the upper limb placed on a radiolucent table with intraoperative fluoroscopy. Draping is performed such that the upper extremity from the proximal third of the arm to the fingers forms the surgical field. No tourniquet is applied. Selection of wires: 2 similarly sized stainless steel K-wires of either 1.2- or 1.5-mm diameter are used. The choice is made depending on the narrowest canal diameter of the radius and the ease of passing 2 wires along the canal of the radius. Our focus is not on filling the canal diameter. The primary goal is to achieve a 50% to 70% span of wire and engagement in the proximal radius and proper alignment of the radial neck fracture. The emphasis is on adequate stabilization of the radial neck, which is achieved through the wide spread of fixation points in the proximal radius metaphysis, rather than the thickness of the wire. Preparation of both wires: The sharp tip of both wires is cut in an oblique manner so as to produce a single beveled tip. This ensures that the wires can be navigated within the radial canal without engaging or perforating the cortex, and at the same time, the beveled tip allows engagement into the proximal radial epiphysis. Subsequently, the cut end is bent, using a pair of pliers or a heavy needle driver, to approximately 30 degrees. The bent end is around 1 cm in length. This bend ensures that there is a good spread of the engaged tips in the proximal radius epiphysis. C bending of the first wire (C wire): The radius is bowed, and recreating this coronal bow in the wire facilitates easy passage. The C wire is laid over the bone to estimate the curve that needs to be incorporated into the wire. A gentle bow is made in the wire using manual manipulation in a manner that the convexity is directly opposite the sharp bend of the tip. S bending of the second wire (S wire): The S wire is prepared in such a manner that the proximal bow is made with convexity opposite and closer to the bent beveled tip. This bow is of less magnitude compared with that of the C wire. The second bow is diametrically opposite to the first bow and is made as the S wire is advanced through the radius. This second bow of the S wire should correspond to the level C wire bow within the radial shaft. The bow is achieved by using the T-handle to hold the wire and using that to bend the wire away from the hand of the patient. Entry point: The image intensifier is used to mark the level of the distal radius lateral entry point, 1.5 cm proximal to the distal radial physis. Following this, a longitudinal incision is made extending from 1 cm proximal to this point to 2 cm distal to it. Tenotomy scissors are used to bluntly expose the radius, with care taken to protect the dorsal radial sensory nerve and its branches throughout the exposure and wire entry. Using a 2.5 mm drill bit and soft tissue protector, a unicortical entry point is made perpendicular to the bone surface. While coming out of the bone with a gentle circular motion, we enlarge the entry point, which will eventually accommodate 2 wires. Reduction of the radial neck fracture: Adequate reduction can be achieved through a manual closed maneuver as previously described, percutaneous, or rarely by open means.5 Wire introduction and initial engagement: After making the initial entry, a T-handle is used to guide the wire(C) along the canal until it reaches the fracture site, followed by a second wire(S). For final head engagement, controlled and soft hammering is applied to the T-handle. T-handle chucks are used for most of the wire advancement, while terminal engagement is done using mallet blows with judicious use of the image intensifier to avoid joint penetration. In our experience, the violation of articular cartilage is quite rare. Arthrogram performed in limited cases shows that the cartilaginous articular cartilage is quite proximal to the visible radiographic bony surface. Hence, penetration through that surface is uncommon. Regardless, the final insertion of the wires should be gentle, under fluoroscopy guidance. Slipping out through the fracture site is more common than violation of the joint surface itself. In the event of slippage, we recommend wire withdrawal and engagement into the subchondral bone after rotating the wire 90 degrees from the previous position. During the terminal engagement of the wires, controlled mallet blows and generous use of fluoroscopy were employed. In addition, we ensure that the wire tips are cut, made blunt, and bent at a significant angle. The other possible implants to use are 1.5 mm titanium elastic nails whose tips have a lower chance of penetration. This engagement of the physis minimizes the risk of wire migration. If sufficient reduction has been achieved, then proceed to Step 11. Fine tuning of the reduction can be made with the rotation of the engaged wire. Upon achievement of satisfactory reduction, the wire is firmly engaged with gentle mallet blows. The risk of penetration into the joint is maximum during this step, with regular fluoroscopy and gentle blows of the mallet. At times, an adequate reduction cannot be achieved by a single wire. The double wire construct can also be used for achieving a gradual reduction by shuttling them back and forth. In such an instance, 1 wire holds the provisional reduction, and 1 aids in the manipulation of the fracture through the rotation of the wire (Fig. 3). Definitive fracture stabilization: The final stabilization is achieved with engagement of both wires in the proximal radius epiphysis with maximal spread between the 2 ends in either the AP or lateral views. To ensure controlled engagement, gentle blows of the mallet are used. Abide by the Rule of Thirds: Divide the radial head into thirds and aim to engage any 2 of them with the wires. It is hypothesized that this spread improves the stability of fixation (Fig. 4). Intraoperative examination of reduction: Following wire placement, fracture stability, radiocapitellar joint (RCJ), and proximal radioulnar joint (PRUJ) alignment are all assessed using dynamic fluoroscopy examination of elbow flexion and extension as well as forearm pronosupination to ensure no blocks to passive motion or unwanted motion through the fracture site are elicited. After being satisfied with the fracture reduction and stability of the fracture pattern, wires are cut flush to the bone. FIGURE 4: Lateral view of the fixation to demonstrate the Rule of Thirds. The radial head is divided into thirds, and the intention is to engage in any 2 of those 1/3’s to achieve maximum stability.POSTOPERATIVE PROTOCOL We keep the above elbow splint for 3 weeks. After that time frame, we start progressive mobilization of the elbow. Wire removal can be planned after fracture union at 6 to 9 months postsurgery. We have not encountered any difficulties during wire removal. We believe that the following factors help minimize complications: use of small diameter wires, avoiding corkscrewing while insertion, and planned timely wire removal (between 6 and 9 mo). EXPECTED OUTCOME The novel “CS” 2-wire technique provides enhanced stabilization of the radial neck fracture, irrespective of the severity of displacement, thereby effectively preventing the risk of future loss of reduction and inviting the possibility of early active postoperative range of motion. The improved stabilization helps to minimize motion at the fracture site, which may reduce additional callus formation and the risk of impingement. By maintaining stable anatomic alignment across the fracture site, long-term functional impairment due to cam-effect impingement and/or RCJ/PRUJ dysfunction is minimized (Fig. 5).FIGURE 5: Illustrative case example. (A) A 10-year-old female with an acute radial neck fracture with concomitant ulna fracture. (B) The radial neck fracture has been stabilized using the CS 2-wire technique. The 6-month postoperative radiographs demonstrate healed fractures with acceptable alignment of the radius, ulna, radiocapitellar, and proximal radioulnar joints. (C) The child had a full range of motion.COMPLICATIONS In addition to the well-established complications associated with the treatment of radial neck fractures, the 2 common issues observed with this technique include difficulty with passage of both wires through the intended entry point and difficulty engaging the radial head. The former challenge can be minimized by either upsizing the drill bit to 3 mm if 1.5 mm wires are used or by enlarging the entry point before insertion by using a curved hemostat to dilate the entry point. The second challenge can be addressed by ensuring the oblique tip of the wire is cut in a manner to keep the tip relatively sharp to facilitate engagement into the radial head without penetration. The 30-degree prebend is an important step to facilitate reduction and secure fixation upon insertion. It is also important to get an adequate spread of the 2 wires in the radial head. These modifications can significantly enhance the efficacy and reliability of the technique while minimizing procedural challenges.

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