Introduction: The anterior and anterolateral approaches to the humerus describe splitting brachialis longitudinally, assuming its fibres run parallel to the shaft. Recent improvements in the understanding of brachialis anatomy however have demonstrated it has two distinct heads, with the bulk of its fibres running oblique relative to the humerus. Attempting to split brachialis longitudinally to the extent required for plate osteosynthesis invariably leads to transection of a significant number of muscle fibres. The authors present a less muscle destructive modification to the anterolateral approach (ALA) based on a bicipital brachialis muscle.
Method: In order to preserve brachialis muscle fibres, the modified ALA elevates the superficial head from the underlying humerus and longitudinally splits the deep head to allow a fixation device to be tunnelled. Case notes of patients with a humeral shaft fracture fixed via the modified ALA were retrospectively reviewed.
Results: Ninteen humeral shaft fractures were fixed via the modified ALA. No post-operative nerve palsies were reported. Of the 19 patients, 14 (73.7%) received clinical and radiological follow-up. All reported being satisfied with their outcome. One developed a superficial wound infection and one (previous diagnosis of spondyloepiphyseal dysplasia tarda) developed a non-union requiring revision surgery. Of the five patients lost to follow-up, two died, and three reported no ongoing orthopaedic issues via telephone.
Conclusions: Improved anatomical understanding of brachialis has resulted in the described modification to the ALA which is less muscle destructive and follows a truer inter-nervous plane. This small series demonstrates satisfactory outcomes using this approach.
Keywords: brachialis; deep head; humerus; modified anterolateral approach; superficial head.