The Neviaser approach for proximal humerus fractures third-generation intramedullary nailing: A cadaver study

Intramedullary nailing (IMN) for proximal humerus fractures is commonly performed through an anterolateral approach. A percutaneous approach through the Neviaser portal has been shown to be an alternative to avoid cuff tendon insertion violation and be used for a third-generation IMN. The aim of the present cadaver study was to confirm whether the Neviaser approach was reproducible to reach the optimal nail entry point, at the top of the humeral head, passing through the muscular portion of the supraspinatus and to evaluate the risk of biceps and neurovascular bundle damage.

This was a basic science surgical technique study with sixteen preserved frozen shoulders from 11 donors (8 females, 3 males) used. All surgical procedures were performed using the third-generation AEQUALIS™ IM Nail. Dissection of each specimen was then performed. The nail entry point through the soft-tissue layer was assessed, determining whether the device was inserted through the supraspinatus muscular or tendinous part. A manual caliper with a precision of 0.1 mm was then used to measure the distances of the device to different anatomic structures.

The nails were inserted through the muscular part in all specimens still having a rotator cuff (RC). The mean distances from the nail entry point to the myotendinous junction and RC footprint were 4 mm (range, 2-6 mm) and 39 mm (range, 36-42 mm), respectively. The distances from the lower tuberosity (LT) head screw and most lateral greater tuberosity (GT) head screw to the long head of the biceps (LHB) groove were 9 mm (range, 8-11 mm) and 15 mm (range, 14-17 mm), respectively. The distance of LT head screw to the anterior circumflex pedicle and the lateral cord of the brachial plexus was 15 mm (range 14-17 mm) and 41 mm (range 32-45 mm), respectively. The distance of the highest distal screw and the lowest proximal screw to the axillary nerve was respectively 32 mm (range, 28-40 mm) and 23 mm (range, 21-25 mm). The nail entry point was entirely within the humeral articular surface and at the bone-cartilage junction in 14 and 2 specimens respectively.

This study demonstrated that a third-generation IMN might be inserted via the Neviaser portal. This approach is safe and allows the insertion of the device through the RC muscular part with a reproducible access to the hinge point and with no risk of neurovascular injury.

IV; Anatomy study; Cadaver Dissection.