Open Reduction with Internal Fixation

Open reduction techniques for humeral nonunion are well described, with reported union rates ranging from 80 to 96% (3-6,11). Jupiter specifically described treatment of atrophic nonunion in obese patients with a medial approach, anterior plate, and vascularized fibular graft. All four nonunions that were treated healed, but not without complication (9). Radial nerve palsy remains a potential risk and is reported to occur in 3 to 29% of nonunion cases (14). The principles of successful treatment include protecting the radial nerve, resecting atrophic nonunions, shortening as required to achieve apposition of well-vascularized fragments, use of a dynamic compression plate, achieving compression at the fracture site, and grafting with cancellous bone (11) (Fig. 2).

Three standard approaches are preferred: anterolateral (15), direct lateral (16), and direct posterior (15). The choice of approach is predicated upon several factors, including the presence of scars from previous surgery, location of the nonunion, presence of radial nerve injury, and health status of the patient. The anterolateral and lateral approaches allow supine positioning, while the posterior approach requires the patient to be either in the lateral decubitus position or prone. The anterolateral and direct lateral approaches allow for extensile exposure of the humerus. Both permit isolation and examination of the radial nerve; however, the direct lateral provides the most extensile exposure of the radial nerve proximally. The posterior approach avoids the radial nerve in the distal third of the humerus, but the nerve directly crosses the operative field in the middle third (17).

Figure 2 Atropic nonunion of humerus following open fracture. A. Preoperative ante- £

roposterior (AP) view. B. AP view of anterior plate with implant failure and angulation. C. Postoperative AP view 3 months following compression plating with demineralized bone matrix graft. D. Postoperative lateral view with cortical bridging in both planes.

Figure 2 Atropic nonunion of humerus following open fracture. A. Preoperative ante- £

roposterior (AP) view. B. AP view of anterior plate with implant failure and angulation. C. Postoperative AP view 3 months following compression plating with demineralized bone matrix graft. D. Postoperative lateral view with cortical bridging in both planes.

If the radial nerve is in the field during the surgical approach, it should be identified and carefully protected. A wide vessel loop or narrow Penrose drain is placed to protect the nerve. Thin vessel loops have a tendency to pull tightly through a small area and may cause more damage to the nerve. The humerus and previously placed implants should be identified. At this juncture it is critical that only enough periosteal dissection be performed to permit implant removal. In hypertrophic nonunions, it is not necessary to take down the entire nonunion. The goal is to stabilize the nonunion site by improving the mechanics of the fixation. In cases with abundant hypertrophic callus, a single narrow 4.5-mm dynamic compression plate is sufficient as long as compression is achieved either through the plate's compression holes or outside the plate with an external ten-sioning device. The length of the plate is determined from the preoperative template. A minimum of six cortices should be fixed with bicortical screws on either side of the nonunion. When a plate is removed, the new plate should span past the original screw holes at each end. In these cases or when the nonunion site spans several centimeters, eight cortices of fixation on either side should be achieved. When the fracture gap appears to be greater than 3 to 5 mm between the bone ends, the external tensioner or other technique, such as use of a laminar spreader positioned against the plate and a screw outside the plate, should be used to reduce the gap. Theoretically, compression through the plate permits 1 mm of compression per hole, and it is usually difficult to achieve more than 3 mm of total compression solely through the plate. A small amount of callus may be removed to allow better contact between the plate and the bone. It is of utmost importance that compression of the bone ends be achieved, as this provides most of the increased stability required to transform a hypertrophic nonunion into a healed fracture. On the table, radiographs are taken to confirm that the preopera-tive goals were achieved and then a layered closure is performed. Physical therapy should begin as soon as possible, with an emphasis on range of motion of the shoulder and elbow. If the surgical goals are met, prognosis is excellent for eventual union.

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