How the InterTAN Nail Performs in Hip Fracture Fixation

The InterTan nail is a cephalomedullary (through-the-bone) nail designed to fix fractures of the upper femur, particularly intertrochanteric hip fractures. What sets it apart from other intramedullary nails is a pair of interlocking screws that thread into the femoral head and compress the fracture as they are tightened, rather than relying on a single lag screw or helical blade. That twin-screw mechanism gives the device stronger resistance to the two failure modes surgeons worry about most: the femoral head rotating on its axis and collapsing into a varus (bowlegged) position. Whether those biomechanical advantages translate into meaningfully better patient outcomes is a question that has generated a substantial body of research over the past decade.

What Makes the Design Different

Most cephalomedullary nails for hip fractures use a single piece of hardware inside the femoral head. The Gamma nail uses a single lag screw; the PFNA (proximal femoral nail antirotation) uses a single helical blade. Both allow some controlled sliding at the fracture site, which helps the bone ends compress together as healing progresses. The downside is that a single-point fixation inside the femoral head does not do much to prevent the head from spinning around the screw’s axis or tilting into varus.

The InterTan nail addresses this with two screws that interlock inside the nail body. As the surgeon tightens the set screw, the two cephalic screws compress the fracture fragments together and lock against each other. Once locked, the construct behaves more like a fixed-angle device than a sliding one, limiting rotation and collapse while still allowing a small amount of controlled shortening at the fracture site. In biomechanical testing, the InterTan construct allowed only about 1.5 degrees of femoral head rotation compared with 5.5 degrees for a sliding hip screw, and it reduced varus collapse from roughly 31 degrees to about 11 degrees under the same loading conditions.¹

How It Performs in Unstable Fractures

The differences in bench testing become more pronounced when fractures are unstable. In a lab comparison using synthetic femur models, the InterTan and Gamma3 nails performed similarly in stable fracture patterns: stiffness and failure loads were almost identical. But when the fracture model was made unstable, the InterTan group showed significantly less fragment displacement once loads exceeded 800 N and withstood a higher force before failure.² The torque resistance was also higher for the InterTan at all tested angles, which reflects that twin-screw advantage in resisting rotation.

This matters because the fractures where implant choice makes the biggest clinical difference tend to be unstable ones. A simple, two-part intertrochanteric fracture in strong bone will heal well with almost any reasonable fixation. It is in comminuted fractures, reverse obliquity patterns, and osteoporotic bone where implant design starts to show its hand.

Comparing Outcomes Against Other Nails

The largest body of evidence compares the InterTan to the PFNA, since both are widely used cephalomedullary nails for intertrochanteric fractures. A systematic review and meta-analysis pooling data from multiple studies found that the PFNA group had shorter operating times, less fluoroscopy use, and less intraoperative blood loss. But when it came to postoperative complications, the InterTan group came out ahead: shaft fractures, varus collapse, screw cut-out, screw migration, and hip or thigh pain were all significantly more likely with PFNA.³ In terms of overall postoperative function, the two nails were comparable.

A separate meta-analysis comparing the InterTan to both the Gamma3 and PFNA reported a similar pattern. The risk of implant cut-out was about 80% lower with the InterTan, and the risk of femoral fracture was similarly reduced.⁴ Revision surgery rates and varus angulation, however, did not reach a statistically significant difference between the devices in that pooled analysis.⁵

When the InterTan is stacked up against the sliding hip screw in a large randomized multicenter trial of 684 patients, the two devices were similar in terms of pain, function, and reoperation rates at one year.⁶ That trial included both stable and unstable fracture types, and the overall finding was that the two devices performed equivalently for the broad population. The advantage of cephalomedullary nails over sliding hip screws tends to become clearer in the unstable subset, which is where most surgeons already prefer nailing.

An individual retrospective study comparing the InterTan to a dynamic hip screw found substantially shorter operative time, less blood loss, fewer fluoroscopy exposures, and a lower complication rate in the InterTan group.⁷ However, that was a small single-center study, and the large randomized trial data above paints a more equivocal picture when fracture types are mixed.

The Operating Room Trade-Off

One consistent finding across studies is that the InterTan takes longer to implant than a PFNA or Gamma nail. A meta-analysis found the InterTan required roughly eight to ten additional minutes of surgery time compared with either device.⁸ A systematic review confirmed that blood loss and fluoroscopy use also tend to favor the PFNA.⁹ In one retrospective comparison, the InterTan group averaged about 72 minutes of operating time versus 52 for PFNA, with fluoroscopy time roughly doubling.¹⁰

For a frail elderly patient, extra minutes under anesthesia and extra radiation exposure are not trivial concerns. Surgeons who favor the InterTan argue that slightly longer surgery is worth the reduced risk of reoperation for cut-out or implant failure down the line. Surgeons who prefer simpler devices counter that for most stable fractures the complication difference is small, and efficiency in the operating room protects the patient too. The honest answer is that both sides have a point, and the choice often depends on fracture stability, bone quality, and the surgeon’s experience with the instrumentation.

Complication Rates and What Drives Them

Cut-out, where the lag screw or blade backs out through the femoral head, is the complication that most drives implant comparisons in the literature. It almost always requires a second surgery. Both a direct comparison study and pooled meta-analyses show cut-out is significantly less common with the InterTan than with the Gamma3 or PFNA.¹¹ Femoral shaft fracture at or below the nail tip is also less frequent.¹²

A meta-analysis of both randomized trials and observational studies offered a nuanced finding. When only randomized controlled trials were pooled, the InterTan showed a shorter tip-apex distance and less hip or thigh pain than PFNA, but the differences in cut-out, reoperation, and femoral shaft fracture did not reach statistical significance. In observational studies, however, the InterTan showed significantly lower rates of screw migration, cut-out, varus collapse, and shaft fracture.¹³ That split may reflect the fact that observational studies tend to include a wider range of fracture complexities and surgeon skill levels than tightly controlled trials do.

Functional Recovery

Most studies report functional outcomes using the Harris Hip Score, a 100-point scale that combines pain, walking ability, range of motion, and daily activities. A retrospective cohort study of elderly patients found that Harris scores were significantly higher in the InterTan group than the PFNA group at one, six, and twelve months, even though fracture healing time was actually shorter in the InterTan group.¹⁴ A separate series evaluating the InterTan in unstable fractures found an average Harris score of about 82 points at six months, with roughly two-thirds of patients rated as having very good hip function.¹⁵

That said, larger meta-analyses generally conclude that the two nail types produce comparable functional results overall. The advantage of the InterTan shows up more clearly in complication prevention than in how well the average patient walks at one year. A patient who avoids a cut-out or a revision obviously has a much better year, but for the majority of patients whose fixation holds without incident, the daily experience of recovery is similar.

Osteoporotic Bone

Weak bone is where the InterTan’s design is thought to matter most. In osteoporotic femurs, the single-point fixation of a PFNA blade or Gamma screw has less bone to grip, and the risk of the hardware backing out rises. A retrospective study with a minimum three-year follow-up in elderly osteoporotic patients found more radiographic complications with PFNA, including screw cut-out, shaft fractures near the nail tip, and varus collapse, while functional outcomes between the two nails remained similar.¹⁶ Another study in elderly patients with primary osteoporosis also described the InterTan as a reliable implant for these fractures.¹⁷

When the InterTan is combined with osteoporosis medication such as alendronate, one study reported shorter fracture healing times and improved hip bone mineral density and Harris scores at follow-up through twelve months, compared with surgical fixation alone.¹⁸ That is not unique to the InterTan; treating the underlying osteoporosis alongside any fracture repair improves outcomes. But it underscores that implant choice is only one variable. Bone quality management matters at least as much.

Reverse Obliquity and Subtrochanteric Fractures

Reverse obliquity intertrochanteric fractures have a fracture line that runs in the opposite direction from the typical pattern, making them biomechanically more like subtrochanteric fractures. They are notorious for resisting fixation. Finite element modeling of these fractures found that the InterTan produced the lowest stress on both the implant and the surrounding bone and the smallest displacement at the fracture site when compared with Gamma3 and ZNN nails.¹⁹ The analysis also showed that the InterTan provided the best resistance to femoral head varus collapse in this fracture type.

For subtrochanteric fractures, which occur just below the intertrochanteric region, the long version of the InterTan nail can be used. A study of complex subtrochanteric fractures treated with long InterTan nails combined with titanium cable cerclage reported excellent or good fracture reduction in all patients, less varus angle loss during healing, and shorter time to full weight-bearing compared with a control group.²⁰ A separate case series using minimally invasive clamp-assisted reduction with the long InterTan reported a mean fracture healing time of about four and a half months, though two patients experienced delayed union.²¹ A comparison with the Gamma3 long nail for a specific type of complex subtrochanteric fracture found similar healing times and hip scores, and no fixation failures in either group.²²

Learning Curve and Surgical Pitfalls

The twin-screw design and heavier instrumentation of the InterTan make it a more demanding implant to learn. A study tracking surgeons’ experience found that technical proficiency improved as case volume grew: key metrics like tip-apex distance and operative time leveled off as surgeons accumulated experience, while partial weight-bearing time and fracture union time remained similar between early and later cases.²³ The tip-apex distance, a predictor of cut-out risk, stayed within the recommended threshold in both groups, suggesting that even during the learning curve the device can be placed safely with proper technique.

A case series documented several iatrogenic fractures that occurred during InterTan implantation. In one case, fat obstruction in an obese patient caused the nail to be inserted at an oblique angle, fracturing the proximal femur. In another, forceful hammering in an elderly woman with fragile bone fractured the distal femur. A third iatrogenic fracture occurred around the distal locking slot during the drilling step.²⁴ These complications are not unique to the InterTan, but the stiffer nail and the force required to seat and interlock the two screws may lower the margin for error in fragile bone. Surgeons transitioning to the device are generally advised to ream the canal carefully, avoid excessive force, and pay attention to the fluoroscopic appearance before committing to nail insertion.

Cost Considerations

The InterTan implant itself is more expensive than a standard single-screw or single-blade cephalomedullary nail. However, an economic analysis that modeled the full episode of care, including the costs of treating complications and reoperations, found that total per-patient costs were about $2,700 lower for the InterTan than for standard-of-care nails. The savings were larger when the InterTan was compared with single helical blade nails (about $3,280 per patient) and smaller against single lag screw nails (about $1,650 per patient).²⁵ The logic is straightforward: if fewer patients need revision surgery, the system spends less overall even though the upfront implant cost is higher.

That modeling, like all health-economic analyses, depends heavily on the complication rates fed into it. If a hospital’s surgeons already achieve very low cut-out rates with cheaper nails, the cost advantage narrows or disappears. The economic case for the InterTan is strongest in settings that treat a high volume of unstable fractures in osteoporotic patients, where the baseline complication risk with other devices is highest.

When Simpler Implants Are Perfectly Fine

It is easy to read the complication data and conclude that everyone with an intertrochanteric fracture should get an InterTan. In practice, the picture is less clear-cut. For a stable two-part fracture in a patient with reasonable bone quality, the risk of cut-out or shaft fracture with any modern cephalomedullary nail is already low. The extra operating time, blood loss, and radiation exposure associated with the InterTan may not be justified if the expected benefit is tiny. The large randomized trial comparing the InterTan to a sliding hip screw across a mix of fracture types found no meaningful difference in pain, function, or reoperation at a year.²⁶

The evidence tilts most clearly toward the InterTan in specific situations: unstable or comminuted fracture patterns, poor bone quality from osteoporosis, reverse obliquity fracture lines, and subtrochanteric extension. In those scenarios the biomechanical advantages translate into clinically meaningful reductions in hardware failure. For more straightforward fractures, the choice between the InterTan and other well-designed nails is less consequential, and factors like surgeon familiarity, operating time, and implant availability often end up deciding the matter.