Retrograde Intramedullary Nailing of Femoral Fractures

Overview

Retrograde femoral nailing began with Küntscher and has evolved into full-length retrograde nails with multiple lengths and diameters, appropriate bows, and multiple distal locking options (lateral-to-medial, anterior-to-posterior and oblique condylar screws) (Rockwood). There is no absolute indication for a retrograde nail, but it has clear advantages in specific situations (AO). Its main advantage is easy access to the entry point through the distal femur with the patient supine (Rockwood).

Indications

Relative Indications (AO; Rockwood; Campbell)

1. Obesity, in which an antegrade entry point is difficult to find (Campbell; AO; Rockwood). In obese patients (BMI ≥ 30), retrograde nailing had shorter operative and fluoroscopy times (Rockwood).

2. Ipsilateral femoral neck and shaft fractures, so that separate devices can be used (Campbell; AO; Rockwood).

3. Floating knee: Femur and tibia fixed through one knee incision (Campbell; AO). Fix the femur first to give a stable proximal limb before nailing the tibia (Rockwood).

4. Polytrauma / multiple injuries: Supine on a radiolucent table, several teams can work at once and no fracture table is needed (Campbell; AO; Rockwood).

5. Bilateral femoral fractures (AO; Rockwood).

6. Unstable spine injuries (AO; Rockwood).

7. Pregnancy: Less fetal radiation exposure (Campbell; AO; Rockwood).

8. Ipsilateral pelvic or acetabular fracture, where an antegrade incision would interfere with later approaches (AO; Rockwood).

9. Uncontaminated traumatic knee arthrotomy, ipsilateral patella fracture or below-knee amputation (AO; Rockwood).

10. Severe soft tissue injury or burns at the antegrade entry site, or an existing proximal femoral implant (AO).

11. Distal-third shaft fractures, where the distal segment is easier to control (Rockwood; Campbell).

12. Open femoral fractures are also a viable option; knee sepsis rate was 1.1% in O'Toole et al. (Campbell). Retrospective reviews have not shown an increased knee infection rate (Rockwood).

Relative Contraindications (Rockwood)

• Subtrochanteric fractures (generally better treated antegrade).

• Limited knee flexion that prevents access to the entry point.

• Patella baja.

• Hip abduction contracture.

At least 5 cm of intact proximal diaphysis is advised to help avoid malunion; in one review of proximal fractures treated retrograde, 35% healed in more than 5° of varus (Rockwood).

Retrograde vs Antegrade

• Randomized trials: Ostrum (100 patients, 10 mm reamed nails): antegrade nails healed about 4 weeks earlier, but overall union was similar; knee pain was equal and thigh pain more common with antegrade nails. Tornetta (69 patients): no difference in union (100%), operative time, blood loss or transfusion (Rockwood).

• Prospective randomized trials found that retrograde nailing needed more secondary procedures to achieve union, but overall union rates were the same; early studies with undersized nails reported lower union (AO).

• Union rates are lower for supracondylar fractures (80–84%) than for shaft fractures (85–100%) (Campbell).

• Complications: Knee pain (13–60%), secondary surgery (12–35%), infection (0–14%) (Campbell).

• Varus–valgus malunion was common with the original extraarticular entry point (12–29%) and is less common with the current intercondylar entry (Campbell).

• Patients should be warned of hip pain after antegrade nailing and knee pain after retrograde nailing (AO).

Preoperative Planning

• Radiolucent table with the C-arm on the opposite side, perpendicular to the femur (Rockwood).

• Have all nail sizes and instruments ready; image or template the contralateral femur in comminuted fractures (Rockwood).

• Length without a fracture table: Ensure full paralysis; options are manual traction (which extends the knee and makes the entry harder), a femoral distractor (proximal pin just above the lesser trochanter, anterior-to-posterior and medial to the nail path; distal pin lateral-to-medial anterior to the nail), a distal femoral traction pin, or percutaneous Schanz pins (Rockwood).

• Always evaluate the femoral neck before and after nailing (Rockwood; Campbell).

• Ipsilateral neck fracture: Priority is anatomic reduction and stable fixation of the neck (often open reduction with plate or screws), then retrograde nailing of the shaft (Rockwood; AO).

Surgical Technique

Positioning

1. Supine on a radiolucent flat-top table. A small bolster under the ipsilateral hip prevents external rotation of the proximal femur (Campbell; Rockwood). Without a bump, keeping the patella pointing anteriorly gives proper rotation (Rockwood).

2. Prep the whole leg up to the iliac crest so proximal locking is possible (Rockwood; Campbell).

3. Rest the knee over a radiolucent triangle or bump. The knee flexion needed to reach the entry point is typically 34–52° (Rockwood); confirm on the lateral view and adjust.

4. The distal segment tends to sag posteriorly; a second soft bump just distal to the fracture helps sagittal alignment (Rockwood). Tibial traction attached to a traction bow, or a tibial traction pin used as a handle, controls the distal fragment (Campbell).

Approach and Entry Point

1. Make a longitudinal incision of 1–4 cm from the inferior pole of the patella toward the tibial tubercle (Rockwood). Approach through a lateral parapatellar, medial parapatellar, or transpatellar tendon incision (Campbell; AO). With a small incision, use the lateral view to make sure it lines up with the entry point (Rockwood).

2. Insert the guidewire into the intercondylar notch (Campbell):

   • AP view: In line with the medullary canal, in or slightly medial to the intercondylar sulcus. Because the femur has 5–9° of valgus, the entry is in line with the canal, not perpendicular to the joint line (Rockwood).

   • Lateral view: In line with the canal, at the anterior end (apex) of Blumensaat's line, just anterior to the femoral origin of the PCL (Campbell; AO; Rockwood). In cadavers, the entry lay 6.2–12 mm anterior to the PCL attachment (Rockwood).

3. Advance the wire into the distal femoral metaphysis. Place a soft tissue protection sleeve to protect the articular cartilage and patellar tendon; perform the whole procedure (entry, reaming) through the tissue protector seated in the notch (Campbell; AO).

4. A multiple-pin "honeycomb" insert can help perfect wire position. Then remove the insert and pass the cannulated entry reamer over the wire (Campbell).

5. Ream into the distal femur with the sleeve in place. Do not use the channel reamer or entry reamer connector in this procedure (Campbell).

6. Pitfall: An incorrect trajectory in the distal fragment, especially in fractures involving the distal metaphysis, causes coronal and sagittal malalignment through nail–canal mismatch. Blocking (Poller) screws or wires may be needed (Campbell; AO). In very distal fractures, center the wire in the distal metaphysis to prevent angulation (Rockwood).

Reduction and Reaming

1. Remove the reamer and wire and insert an intramedullary reduction tool into the distal fragment (Campbell).

2. Reduce the fracture and advance the tool into the proximal fragment up to the level of the lesser trochanter. Small bumps under the posterior thigh help sagittal reduction (Campbell). Joystick Schanz pins and other aids are as for antegrade nailing (Rockwood).

3. Place the ball-tipped guidewire past the lesser trochanter, confirm in two planes, and remove the reduction tool (Campbell; Rockwood).

4. Ream over the wire to 1–1.5 mm larger than the planned nail diameter (above the first size with cortical chatter) (Campbell; Rockwood).

   • Monitor reamer passage on the lateral view so the tibial plateau, menisci and inferior pole of the patella are not damaged; adjust knee flexion as needed. A drill sleeve or a cut 10 mL syringe can act as an inexpensive protective cannula (Rockwood).

   • With an associated proximal femoral, femoral neck or acetabular fracture, consider overreaming by 2 mm to avoid forceful impaction (Rockwood).

   • In damage control cases, a small-diameter unreamed, unlocked nail has been described as an alternative to external fixation until definitive reamed locked nailing (Rockwood).

5. Recheck that the wire tip is at the level of the lesser trochanter (Campbell).

Nail Length and Insertion

1. Apply traction to restore length. Measure nail length with a ruler over the guidewire and make sure the ruler is countersunk, easiest to judge on the lateral view (Campbell).

2. Remove the entry portal tool and insert the nail on its targeting guide, maintaining traction to avoid shortening (Campbell).

3. Nail depth:

   • Proximally: At or just above the lesser trochanter (Campbell; AO; Rockwood), ideally proximal to it to reduce stress fractures (Rockwood).

   • Distally: Countersunk beneath the articular cartilage. A nail protruding only 1 mm into the joint increased patellar contact at 90–120° of knee flexion (Rockwood).

4. Confirm countersinking on the lateral view, then remove the guidewire (Campbell).

Distal Locking (Through the Guide)

1. Pass the drill sleeve and trocar through the targeting guide, mark the skin, make a stab incision and dissect bluntly to bone (Campbell).

2. Seat the drill guide on bone, drill to the far cortex, read the length, and complete drilling (Campbell).

3. Insert the screw by hand and check length and position on AP and lateral views (Campbell). A notch (intercondylar) view helps judge screw length and avoid painful screw tips (Rockwood).

4. Screws may be lateral-to-medial, anterior-to-posterior or oblique depending on the system; newer nails offer screws that lock into the nail, which may help in poor bone (Rockwood).

5. If the fracture is distracted after distal locking, drive the nail further to close the gap before proximal locking; in axially unstable fractures that have shortened, back-slap the nail to regain length before proximal locking (Rockwood).

Alignment Check

1. Check alignment and length with an electrocautery cord stretched from the ASIS through the center of the femoral head, the center of the knee and the center of the tibial plafond, and check the lateral view (Campbell).

Proximal Locking (Freehand)

1. Place the proximal screw anteroposteriorly at or above the level of the lesser trochanter to minimize injury to the femoral nerve branches and vessels (Campbell; Rockwood). Avoid internal rotation of the nail within the femur; a slightly larger incision that lets you palpate or see the bone reduces the risk to the profunda femoris branches (Rockwood).

2. Localize the hole with the perfect circle technique; make a longitudinal incision, divide the fascia sharply and dissect bluntly to bone. Protect the branches of the femoral nerve (Campbell).

3. Drill, measure, and insert the screw with a captured screwdriver (Campbell). Static or dynamic proximal locking depends on fracture stability and bone contact (Rockwood). Acute femoral nails should be statically locked (AO).

4. Recheck alignment and reduction on multiple views (Campbell).

Final Checks

1. Image the hip in live fluoroscopy with internal and external rotation and push–pull for an occult femoral neck fracture (Campbell).

2. Irrigate the knee thoroughly to remove reaming debris (Rockwood). Close in layers.

3. Complete the same final checks as for antegrade nailing: length and rotation, thigh compartments, knee ligaments, and an AP pelvis radiograph with both hips internally rotated (Campbell).

Postoperative Care

• Rehabilitation depends on fixation stability and fracture pattern and must be individualized (Campbell).

• With stable fixation, start a motion program within 24–48 hours (Campbell). Active and passive motion and strengthening can begin without restriction once the fracture is locked; consider CPM if the patient cannot cooperate with therapy (Rockwood).

• Weight bearing as tolerated is usually allowed (Campbell; Rockwood).

• Intercondylar or supracondylar fractures: Protected weight bearing until radiographs show progression, usually 6–8 weeks (Campbell).

• Radiographs at 6 and 12 weeks, then every 6–8 weeks until union; new groin pain should prompt investigation for a missed femoral neck fracture (Rockwood).

Complications

• Knee pain: In one study, 23% had knee pain and 19% needed removal of a distal screw; it may be caused by a long, symptomatic distal locking screw (Rockwood).

• Articular cartilage or PCL injury from an incorrect entry point (Rockwood).

• Septic knee after retrograde nailing of open fractures has been reported (AO), but retrospective reviews have not shown increased knee infection (Rockwood).

• Heterotopic ossification around the knee; synovial metallosis has been reported, of unknown clinical significance (Rockwood).

• Studies have not shown increased knee degeneration or loss of motion as long as the nail is buried beneath the articular surface (AO).

• Nerve or vessel injury during proximal locking (profunda branches, femoral nerve) (Rockwood; Campbell).

• Malalignment in proximal fractures (Rockwood).

References

1. Rudloff MI. Fractures of the lower extremity. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Philadelphia: Elsevier; 2026. Chapter 59, Technique 59.27.

2. Balogh ZJ. Femur, shaft (including subtrochanteric fractures). In: Buckley RE, Moran CG, Apivatthakakul T, eds. AO Principles of Fracture Management. 3rd ed. Stuttgart: Thieme; 2017. Chapter 6.6.2. (Turkish edition: AO Kırık Tedavisinin Prensipleri.)

3. Adams JD Jr, Jeray KJ. Femoral shaft fractures. In: Tornetta P III, Ricci WM, Ostrum RF, McKee MD, Ollivere BJ, de Ridder VA, eds. Rockwood and Green's Fractures in Adults. 10th ed. Philadelphia: Wolters Kluwer; 2024. Chapter 57. (Turkish edition: Erişkin Kırıkları.)