Adolescent Lateral Entry Femoral Nail
The adolescent lateral entry femoral nail (ALFN) is intended for use in adolescents and small stature adults depending on the persons' weight, body size, physiological development, neurological development, and neuromuscular coordination. The ALFN is indicated to stabilize fractures of the femoral shaft, subtrochanteric, ipsilateral neck/shaft and impending pathological fractures, as well as nonunions and malunions of the femur (Fig 1). The ALFN can also be used to stabilize corrective osteotomies in bone dysplasias such fibrous dysplasia where femoral deformity is an issue.
Conventional antegrade nailing of the femur in this age group is a concern because of the possibility of avascular necrosis of the femoral head. This is rare but devastating. The ALFN has a lateral trochanteric entry point and a double curved configuration (double bend in two planes and additional tip bend) to avoid compromising the ascending branch of the medial femoral circumflex artery near the piriformis fossa. The recommended entry site is on the bare aspect of the greater trochanter 1520 mm distal to the tip of the greater trochanter and forms an angle of 1214 lateral to the greater trochanter, as measured from the lateral entry point to a point 20 mm distal to the lesser trochanter (Fig 2).
The ALFN is cannulated and has 8.2 mm shaft diameter and a proximal diameter of 11 mm. The nail comes in lengths from 240400 mm in 20 mm increments. Additional diameters of 9 mm and 10 mm are under development. For the opening, a 13.0 mm cannulated drill bit is used.
The ALFN features the same proximal locking options as the LFN (two recon locking screws, one transverse slot for a static or dynamic locking screw, and one 120 antegrade locking screw). The recon screws are 5.0 mm solid, self-tapping shaft screws available in lengths from 50125 mm. For distal locking, two lateral to medial locking screws can be used. It is of major importance to ensure that the wires and drill bits used for the recon screw insertion do not cross the capital femoral physis, and that the distal end of the nail stops 15 mm short of the distal femoral physis.
The adolescent lateral entry femoral nail is part of the expert nail family, therefore most instrumentation is identical, except for a new insertion handle aiming arm (Fig 3), 13 mm drill sleeve, and 5.0 mm recon screw drill bit. The ease of finding the entry point is maximized if the greater trochanter is positioned in profile to the beam of the C-arm. This can be done in either supine or lateral decubitus position.
A 15-year-old male sustained an extensive soft-tissue injury with loss of bone after a gunshot (low-velocity, large caliber bullet). Neurovascular status intact, large exit wound.
The open injury (Fig 1) was debrided and cleansed. There was missing bone from the femur. Open but rapidly closing growth plates.
Fig 1 Preoperative lateral x-ray.
After stabilizing the fracture with an intramedullary nail (Fig 2) the patient was mobilized with weight bearing as tolerated. Uneventful healing and range of motion of the knee and functional ambulation returned to normal. Alignment of the fracture has been maintained with healing and maturation of callus processing as predicted. Blood supply to the proximal femur has been reserved with no signs of avascular necrosis. The ALFN's lateral entry point makes the nail insertion safer and diminishes the risk of circumflex artery injury.
Fig 2 Immediate postoperative AP x-ray.
Fig 3ab AP x-rays 6 months postoperatively.
Fig 3cd Lateral x-rays 6 months postoperatively.
Case provided by Richard Reynolds, Detroit, USA
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