Gamma nail

The gamma nail or trochanteric nail is an osteosynthetic implant designed to treat proximal femoral fractures in the trochanter area with a closed intramedullary fixation method.

The gamma nail consists of a funnel-shaped intramedullary nail with slight bending to reflect proximal femoral diaphyseal trochanteric morphology, a large proximal opening, which features a sliding mechanism for a large femoral neck lag screw and small holes in the distal part enabling distal femoral locking of the implant ^1,2.

Gamma nails come in different lengths, longer nails are designed to provide stability in intertrochanteric and subtrochanteric fractures with diaphyseal fracture extension ^1,2. In addition, there are different lag screw angulations available.

History and etymology

The gamma nail was introduced for the treatment of proximal femoral fractures in 1988 ^1-3. The second generation of gamma nail came up in 1997 and the current generation the Gamma3 nail in 2006 ³. The Gamma3 intramedullary nailing system is made by Stryker although other intra-medullary devices are available by other companies such as Smith & Nephew and Zimmer. It is important to know that not all intra-medullary nail fixation devices are Gamma3. 

Indications

The main indication is the treatment of pertrochanteric, intertrochanteric and subtrochanteric fractures fracture type AO/OTA 31-A1 31-A2 and 31-A3 ³.

Other indications include impending pathological fractures, tumour resections and revision procedures.

Contraindications

Contraindications of gamma nail fixation include medial femoral neck and of course femoral head fractures.

Procedure

The surgical technique comprises several main steps including the following ^1,2:

• exact anatomic closed reduction on the traction table
• a lateral approach to the proximal femur is usually used
• the entry point is identified under fluoroscopy and an entry guide-wire or awl is inserted
• determination of nail length (180mm for short Gamma nails; for long nails, this is determined by measurement of the long guidewire), and angle and anteversion of lag screw insertion
• reaming of the femoral medullary canal from the insertion point at the top of the greater trochanter and then a determination of the diameter of the nail (if a long nail is used)
• insertion of the nail
• insertion and advancement and fixation of the femoral neck lag screw
• distal locking either using the attached jig ⁵ or via perfect circles technique

Complications

Complications of gamma nail fixation include the following ^1,2:

• haematoma formation
• secondary displacement
• infection
• fracture non-union
• periprosthetic fracture
• implant malposition (e.g. cut-out)
• osteonecrosis of the hip
• hardware failure (rare)

general complications associated with proximal femoral  surgery:

• cardiovascular complications
• pneumonia
• pulmonary oedema
• pulmonary embolism

Radiographic features

Nail position, fragment position and fracture healing can be assessed with an anteroposterior view and a lateral view of the hip. The position of the femoral neck lag screw should be ideally in an inferior position from the AP view and a centred position from the lateral view ^1,2. The femoral neck lag screw should be positioned at least 1 mm from the joint space.

Radiological report

The radiological report should include a description of the following features:

• implant malposition e.g. penetration of the femoral neck lag screw through the femoral head
• fragment displacement
• implant loosening
• signs of fracture healing
• hardware failure

Outcomes

The use of gamma nails is associated with a moderate amount of blood loss requiring an average of 2 units with the first generation gamma nails.

Weight-bearing is achieved within the first week in more than 80% of patients with excellent and good overall outcomes in a similar percentage ^1-3.

Fracture healing occurs usually within 12 weeks.

Advantages

In comparison to open reduction methods like the dynamic hip screw, the gamma nail features a decreased amount of tissue trauma and operative blood loss ^1,2,4.

Disadvantages

Disadvantages included more technical and intraoperative complications as newly induced periprosthetic fractures or secondary dislocation ¹. The periprosthetic fracture rate was significantly reduced with the two later generations ³.