We describe a distal modification of the anterolateral approach to the humerus that allows for adequate exposure of humeral shaft fractures with improved visualization and protection of the radial nerve. Humeral shaft fractures account for roughly 3% of the total fracture burden.1 These injuries are seen both in high energy trauma in young patients and lower energy mechanisms in all age groups. Many isolated humeral shaft fractures are treated nonoperatively with a coaptation splint followed by functional bracing such as with a Sarmiento brace with a goal of maintaining <20 degrees of anterior angulation, <30 degrees of varus/valgus angulation, and <3 cm of shortening.2,3 Predictors of failure for conservative treatment include transverse or short oblique fracture patterns and patients with large body habitus such as obese females with pendulous breasts. The indications for surgical treatment of a humeral shaft fracture include failure of conservative treatment, open fractures, those with neurovascular injuries or compartment syndrome, ipsilateral forearm fractures, or polytrauma patients. The most common surgical fixation of a humeral shaft fracture is with open reduction internal fixation. Approaches for open reduction internal fixation include direct lateral, anterolateral, and posterior depending upon the fracture location. A worrisome complication is radial nerve injury. The incidence of radial nerve injuries during humeral shaft fractures has been reported between 1% and 24%.4–7 A 2005 review by Shao et al7 found that radial nerve injuries occur most commonly with transverse and spiral morphology fractures of the middle and middle-distal shaft of the humerus, with no difference noted in the rate between open and closed fractures as well as no difference between conservatively treated fractures and those treated with early operative fixation. Seventy-one percent of radial nerve injuries spontaneously recovered and 88% recovered overall with average onset of recovery at 7 weeks and average time to full recovery at 6 months.7 With this in mind, protection of the radial nerve during fixation is critical.
Traditionally, the anterolateral approach to the humerus begins proximally at the deltopectoral interval and extends distally between the deltoid and biceps brachii. Following the lateral edge of the biceps, the incision then curves medially to end in the interval between the distal insertion of the biceps and the mobile wad. The superficial dissection is then carried out with the biceps being retracted medially, taking care not to injure the lateral antebrachial cutaneous nerve in the distal portion of the incision. Retracting the biceps reveals the brachialis, which has dual innervation by both the musculocutaneous nerve and the radial nerve, and the brachioradialis, which is innervated by the radial nerve. The radial nerve typically is found between the brachialis and brachioradialis and should be carefully identified before proceeding. To access the humeral shaft for repair of fractures, the brachialis must then be elevated off of the periosteum.
This traditional anterolateral approach to the humerus places both the radial nerve and lateral antebrachial cutaneous nerves at risk particularly during the distal dissection where the radial nerve is in close contact with the bone and can be injured. With the traditional anterorolateral approach curving anterior distally, fractures which require plate fixation in the distal portion may be more prone to radial nerve injury during vigorous retraction such as with a Hohmann (Fig. 1).
We propose a modified anterolateral approach to the humerus that provides both excellent exposure of the fracture and protection of the radial nerve in the distal portion. The incision is made along a line that is drawn between the coracoid process of the scapula proximally and the lateral epicondyle of the distal humerus (Fig. 2). This contrasts with the traditional anterolateral approach that curves anteromedially in the distal portion in order to follow the lateral edge of the biceps. Once the incision is made, the superficial dissection is again carried out in a similar manner, retracting the biceps brachialis medially to access the brachialis and brachioradialis. Rather than curving medially, the modified anterolateral approach to the humerus continues toward the lateral condyle of the elbow. This in theory reduces the chance of encountering the radial nerve during dissection as it should be visualized as it travels obliquely across the distal dissection in a predictable manner (Figs. 3, 4). In addition, the lateral path of the distal incision avoids the lateral antebrachial cutaneous nerve which exits more anteriorly at the lateral portion of the distal biceps. The brachialis can then be elevated off of the periosteum of the humerus to gain access for fracture repair. During exposure, one should be cautious with placement of Hohmann type retractors in the distal one third of the humerus as the radial nerve is in intimate contact with the bone. Often times if the traditional anterolateral approach is used and the plate extends distally, these retractors are used vigorously for exposure and may lead to radial nerve injury. Therefore, in conjunction with our distal modification, we do not use Hohmann type retractors distally. We instead use Weitlaners after visualizing our dissection to reduce the risk of nerve injury.
In summary, the modified anterolateral approach to the humerus provides excellent exposure for repair of humeral shaft fractures. This exposure encounters the radial nerve in a predictable manner crossing obliquely through the distal portion of the incision and minimizes chances of iatrogenic injury.
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