The term gamma nail has become the common search name for a whole implant class: the short or long cephalomedullary nail used to fix intertrochanteric and subtrochanteric femur fractures. Different manufacturers build their own systems, and the surgical technique is broadly shared across all of them. This guide walks through the procedure as it is actually done on the fracture table — positioning, entry point, canal preparation, proximal screw placement and distal locking — using the cephalomedullary nail geometry we supply at BoneCraft as the reference. It is written for surgical teams and procurement staff who want a clear picture of the workflow before specifying implants. Final technique decisions always belong to the operating surgeon.
What the cephalomedullary nail does in a trochanteric fracture
An intertrochanteric fracture separates the femoral head and neck fragment from the shaft. The cephalomedullary nail sits inside the medullary canal and carries the load down the femur while a large lag screw or helical blade crosses the nail into the femoral head to hold the head-neck fragment. Because the implant is load-sharing and centrally placed, it tolerates early weight bearing far better than a lateral plate in unstable patterns. The nail body typically sits at a neck-shaft angle of 130 degrees, with proximal locking through the lag screw and distal locking through one or two transverse screws.
Positioning and reduction on the fracture table
The patient goes on the fracture table supine, with the injured leg in traction and the uninjured leg abducted or in a heel-up position to leave room for the C-arm. Closed reduction comes first: traction restores length, and gentle internal rotation usually brings the fragments into alignment. Both AP and lateral fluoroscopy views must confirm the reduction before any incision is made, because a nail will hold whatever position the fracture is in when it is inserted. A lateral decubitus position on a radiolucent table is a valid alternative, and many surgeons prefer it for obese patients.
Entry point and canal preparation
A small incision is made proximal to the greater trochanter. The entry point for a modern cephalomedullary nail is the tip or slightly medial aspect of the greater trochanter, aligned with the femoral canal on the AP view and centered on the lateral view. Starting too far lateral risks varus malalignment of the head fragment; starting too far medial risks fracturing the medial cortex. An awl or curved guide pin opens the canal, a ball-tipped guide wire is passed across the reduced fracture into the distal fragment, and the canal is reamed in half-millimeter steps until cortical chatter is felt. The nail diameter chosen is usually one to one and a half millimeters below the final reamed diameter.
Short nail or long nail: selection logic
Nail length is the main planning decision. A short cephalomedullary nail, typically 180 mm, is enough for stable intertrochanteric patterns with an intact lateral wall and no subtrochanteric extension. A long nail is required when the fracture line runs into the subtrochanteric region, when the lateral femoral wall is compromised, or when the bone quality or fracture geometry calls for protection of the whole femur. Long nails commonly run from 300 to 440 mm and are matched to canal diameter at the isthmus.
| Feature | Short nail (180 mm) | Long nail (300–440 mm) |
|---|---|---|
| Typical fracture pattern | Stable intertrochanteric | Unstable, reverse oblique, subtrochanteric extension |
| Distal locking | Single static screw through the jig | Static or dynamic screws, freehand or jig |
| Surgical time | Shorter, less reaming | Longer, full-length reaming |
| Stress protection | Intertrochanteric region | Entire femur |
BoneCraft stocks both versions — the short cephalomedullary nail for stable trochanteric patterns and the long cephalomedullary nail for extended protection — together with the antegrade proximal femoral nail for shaft-level indications. The full range sits under the hip and femur collection.
Inserting the nail and placing the proximal screw
The nail is mounted on the targeting jig and inserted over the guide wire with gentle rotation, never hammered through resistance. Depth is set so the lag screw will pass into the center or slightly inferior third of the femoral head on the AP view. Through the jig sleeve, a guide wire for the lag screw is drilled into the head-neck fragment. Its position is judged by the tip-apex distance, the sum of the distances from the wire tip to the apex of the femoral head on AP and lateral views. A combined tip-apex distance under 25 mm is the accepted threshold for low cut-out risk. Once the wire sits correctly, the channel is reamed, and the lag screw or blade is inserted and seated. A secondary anti-rotation screw or compression mechanism is engaged where the system design provides one.
Distal locking and completion
Short nails lock distally through the targeting jig. For long nails, distal locking is done freehand with the C-arm giving a perfect-circle view of the locking hole, or through an extended jig where the system offers one. Static locking is the default; dynamic locking is chosen when controlled axial compression at the fracture is wanted. Fracture compression is applied through the nail mechanism before the distal screws go in, and traction is released only after locking is complete. An intramedullary nail end cap closes the proximal end of the nail to keep bone ingrowth out of the threads and to fine-tune lag screw position. Wounds are closed in layers, and postoperative weight bearing is set by the operating surgeon according to fracture stability and bone quality.
Pitfalls that cause revision
Three technical errors account for most failures. A lateral entry point drives the head fragment into varus, which raises the load on the lag screw and invites cut-out. A tip-apex distance over 25 mm places the screw too far from the dense subchondral bone of the head, with the same result. And premature weight bearing on an unlocked or poorly compressed construct lets the fracture settle onto the screw. Each of these is avoidable with disciplined fluoroscopy at the entry step, careful tip-apex measurement, and honest assessment of fracture stability before the rehabilitation plan is written.
Sourcing cephalomedullary nailing systems
BoneCraft is an independent distributor of genuine Zimmer Biomet trauma implants, including the cephalomedullary nailing family described in this guide. Hospitals and distributors who need short or long nails, end caps and locking screws from stock can reach our team for availability and lot documentation.
Frequently asked questions
Is gamma nail a generic implant name?
No. Gamma nail is a trade name owned by its manufacturer, but surgeons and purchasing staff use it informally for the whole cephalomedullary nail class. When specifying implants, name the geometry — cephalomedullary nail, 130-degree neck-shaft angle, short or long — rather than any single brand.
Where is the correct entry point for a cephalomedullary nail?
At the tip or just medial to the tip of the greater trochanter, in line with the medullary canal on both fluoroscopy views. A lateral start pushes the reduction into varus and is the entry error most often linked to failure.
What tip-apex distance is acceptable for the lag screw?
The combined tip-apex distance, measured on AP and lateral views, should stay below 25 mm. Values above that threshold are associated with a higher risk of the screw cutting out of the femoral head.
When is a long nail preferred over a short nail?
When the fracture is unstable, reverse-oblique, extends into the subtrochanteric region, or when the lateral femoral wall is broken. A long nail protects the whole femur and bridges stress risers that a short nail leaves exposed.
Static or dynamic distal locking?
Static locking is standard for most intertrochanteric fractures. Dynamic locking is selected when the surgeon wants controlled axial settling at the fracture site. The choice is made case by case by the operating surgeon.
Why is an end cap used on the nail?
The end cap seals the proximal threads of the nail against bone ingrowth, which makes later removal easier, and in several systems it also captures the lag screw to resist rotation and back-out.
When can the patient bear weight after nailing?
Many stable patterns fixed with a well-placed cephalomedullary nail tolerate early weight bearing as tolerated, but the rehabilitation plan is always set by the operating surgeon based on fracture stability, reduction quality and bone stock.
Gamma Nail is a trademark of its respective owner. Zimmer Biomet, ZNN and NCB are trademarks of their respective owner. BoneCraft is an independent distributor of genuine Zimmer Biomet products and is not affiliated with, sponsored by, or endorsed by the trademark owners.
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