We analyzed a total of 35 patients who had humeral distal fracture and were treated with the modified combined anterolateral and lateral approach. They were followed up for a minimum of two years. The average time to bone union was 11.2 weeks (range, 8 to 20 weeks). On average, patients took 10.2 weeks (range, 2 to 32 weeks) to return to work; male patients with advanced work loading took 11 weeks (range, 2 to 32 weeks), while the female group took 8.7 weeks (range, 4 to 12 weeks). The average range of motion of the elbow joint was 132.6° (range, 3.3° to 135.9°). The MEPI revealed 21 cases of excellent performance and 13 cases of good performance; the average functional score was 92.86. New development of radial nerve injury was not observed. Four cases with radial nerve palsy that existed preoperatively completely recovered 31 weeks postoperatively on average. There was no operative wound infection. and no case of complication such as displacement, non-union, or mal-union. Forty percent of the cases (14/35) exhibited mild and intermittent elbow pain, and there was no case of elbow instability or discomfort with normal activity.

There is a high risk of iatrogenic radial nerve injury during plate fixation in the treatment of distal humerus fracture5,6,15) and nonunion usually develops due to inadequate space. This may raise serious concerns even for well-trained specialists. Thus, the surgical outcome may depend on attainment of protection of the radial nerve and the securing of adequate space for firm fixation. The authors investigated the need for a modified surgical approach.

Commonly used humerus approaches are anterolateral, posterior, posterolateral, and lateral approaches.3,9,16-19) Each has its own limitations due to the location of the fracture, patient's position, and possibility of radial nerve damage. The anterolateral approach is widely used for proximal and mid-shaft humerus fracture as it is safe, without the need for dissection of the radial nerve. But when the fracture is located distally, there is a high risk of traction radial nerve injury because the nerve is forcefully pushed laterally for reduction and internal fixation. Regarding distal humerus fracture, posterior or posterolateral approaches are mostly used because these methods do not require radial nerve traction.7,17,20) These approaches can easily expose the posterior aspect of the distal humerus; therefore, acute anatomical reduction is possible, and it is easy to apply the internal device. But as the triceps is divided longitudinally with dissection, complications such as bleeding, triceps muscle weakness, and limitation of elbow motion may occur. As well, when proximal dissection is needed, exploration of the radial nerve is difficult due to its anatomical course: it runs through the triceps and is tethered to the triceps and radial groove of the humerus.7,17) Further access to the proximal humeral neck is completely blocked because of the axillary nerve and the posterior humeral circumflex artery. Also, because patients should be maintained in a lateral or prone position, this approach has limitations in patients with multiple injuries and unstable spine damage.

Recently, lateral approaches have been widely used and it has many advantages such as easy examination of the radial nerve, practicability of the operation in the supine position, and wide range of accessibility. One of its disadvantages is that radial nerve exploration is always required in accessing the proximal humerus. As a result of nerve exploration, the radial nerve is placed directly above the internal device and this can lead to formation of undesired fibrosis around the internal device and nerve.21)

To overcome the drawbacks of the above approaches, we thought of alternative ways that allow access with just one skin dissection over the entire humerus, do not require dissection of the radial nerve, offer enough fixation space without excessive traction to prevent nerve damage, and allow expansion to proximal or distal aspects to treat accompanying injuries. We designed a combined anterolateral and lateral approach. Through this method, broad access to the proximal aspect of the humerus is easily achieved, as it is in the anterolateral approach. Likewise, the risk of radial nerve injury during the approach towards the distal humerus portion, which is a disadvantage of the anterolateral approach, is prevented by using the lateral approach. The radial nerve is protected in its course between the brachialis and brachioradialis.

Specialists tend to agree that the safest technique for the protection of the radial nerve is to explore the nerve initially and practise caution during the operation. When our technique is performed extraperiosteally and is free of muscle tension, it provides a similar level of safety even without direct radial nerve dissection. If there is a need for nerve exploration, it can be done easily without an additional incision. Finally, the plate is positioned slightly anterior and inferior to the radial nerve without direct contact. Thus fibrosis around the nerve is avoided, and a safe operation is possible as the metal plate and radial nerve are separated from each other by a certain distance.

Non-union of a distal humerus fracture may occur from fixation failure. To prevent this, it is necessary to secure adequate fixation. Our method lets operators secure enough space up to the lateral supracondylar ridge of the humerus with respect to the olecranon fossa and allows the use of a metal plate with sufficient length and four or more screw fixations. One of the disadvantages of metal plate insertion is that the metal plate can be placed unnaturally because it has to be placed in a very narrow area in the lateral humerus, and so the shape may not fit along the lateral supracondyle of the humerus. There have been a few cases of patients complaining of discomfort due to the metal plate's extrusion from the lateral epicondyle. Therefore, if a metal plate can be placed in such a way that it anatomically fits with the lateral epicondyle of the humerus, it will be more useful and yield much more stable internal fixation (Fig. 6).

Minimally invasive plate osteosynthesis is another option for treating humerus fracture. This technique offers a theoretical decrease in soft tissue dissection but cannot avoid the occurrence of iatrogenic radial nerve palsies and inadequate fixation. Pospula and Abu Noor22) reported two cases with perioperative complications. From this clinical study, we consider that our approach can be usefully applied when the plate is inserted from the distal lateral cortex toward the proximal anterior cortex of the humerus through a submuscular extraperiosteal tunnel. We presume that use of the newly designed plate (Fig. 6) will avoid the problems of radial nerve injury and inadequate fixation space.

A modified combined anterolateral and lateral approach for the treatment of distal humeral fracture and non-union ensures an easy approach to the entire humerus, a lowered risk of radial nerve injury and the performance of complication-free revision surgery during the distal humerus approach and harmless revision surgery during the distal humerus approach. This approach also provides adequate fixation space and therefore makes delicate fixation of the plate easy.